Energy › Renewable Energy, Sustainability and the Environment

Iron oxide chemistry and applications

Works Count: 42270

Wikipedia

Description

This cluster of papers focuses on the advancements in solar water splitting technology, particularly the use of hematite-based photoelectrodes and nanostructures for efficient photoelectrochemical water splitting. The research covers topics such as surface charging, catalysis, nanostructure design, and the role of various dopants in improving the efficiency of solar water splitting.

Keywords

Hematite; Photoelectrodes; Water Splitting; Nanostructures; Photoelectrochemical; Solar; Nanorods; Catalysis; Surface Charging; Photooxidation

The Iron Oxides

2007-12-17

R. M. Cornell , U. Schwertmann

This chapter contains sections titled: The Major Iron Oxides Less Common or Rare Iron Oxides Iron Oxides in the Environment This chapter contains sections titled: The Major Iron Oxides Less Common or Rare Iron Oxides Iron Oxides in the Environment

The iron oxides: structure, properties, reactions, occurrences and uses.

2003-09-25

R. M. Cornell , U. Schwertmann

1. Introduction to the Iron Oxides. 2. Crystal Structure. 3. Cation Substitution. 4. Crystal Morphology and Size. 5. Surface Area and Porosity. 6. Electronic, Electrical and Magnetic Properties. 7. Characterization. … 1. Introduction to the Iron Oxides. 2. Crystal Structure. 3. Cation Substitution. 4. Crystal Morphology and Size. 5. Surface Area and Porosity. 6. Electronic, Electrical and Magnetic Properties. 7. Characterization. 8. Thermodynamics. 9. Solubility. 10. Surface Chemistry and Colloidal Stability. 11. Adsorption of Ions and Molecules. 12. Dissolution. 13. Formation. 14. Transformations. 15. Rocks and Ores. 16. Soils. 17. Organisms. 18. Products of Iron Metal Corrosion. 19. Applications. 20. Synthesis. 21. Environmental Significance. References. Subject Index. Sources of Figures and Tables.

Absorption and Scattering of Light by Small Particles

1998-04-23

Craig F. Bohren , Donald R. Huffman

BASIC THEORY. Electromagnetic Theory. Absorption and Scattering by an Arbitrary Particle. Absorption and Scattering by a Sphere. Particles Small Compared with the Wavelength. Rayleigh--Gans Theory. Geometrical Optics. A Potpourri of … BASIC THEORY. Electromagnetic Theory. Absorption and Scattering by an Arbitrary Particle. Absorption and Scattering by a Sphere. Particles Small Compared with the Wavelength. Rayleigh--Gans Theory. Geometrical Optics. A Potpourri of Particles. OPTICAL PROPERTIES OF BULK MATTER. Classical Theories of Optical Constants. Measured Optical Properties. OPTICAL PROPERTIES OF PARTICLES. Extinction. Surface Modes in Small Particles. Angular Dependence of Scattering. A Miscellany of Applications. Appendices. References. Index.

View PDF Chat

Synthesis, Properties, and Applications of Iron Nanoparticles

2005-03-31

Dale L. Huber

Abstract Iron, the most ubiquitous of the transition metals and the fourth most plentiful element in the Earth’s crust, is the structural backbone of our modern infrastructure. It is therefore … Abstract Iron, the most ubiquitous of the transition metals and the fourth most plentiful element in the Earth’s crust, is the structural backbone of our modern infrastructure. It is therefore ironic that as a nanoparticle, iron has been somewhat neglected in favor of its own oxides, as well as other metals such as cobalt, nickel, gold, and platinum. This is unfortunate, but understandable. Iron’s reactivity is important in macroscopic applications (particularly rusting), but is a dominant concern at the nanoscale. Finely divided iron has long been known to be pyrophoric, which is a major reason that iron nanoparticles have not been more fully studied to date. This extreme reactivity has traditionally made iron nanoparticles difficult to study and inconvenient for practical applications. Iron however has a great deal to offer at the nanoscale, including very potent magnetic and catalytic properties. Recent work has begun to take advantage of iron’s potential, and work in this field appears to be blossoming.

The absolute energy positions of conduction and valence bands of selected semiconducting minerals

2000-03-01

Yong Xu , Martin A. A. Schoonen

The absolute energy positions of conduction and valence band edges were compiled for about 50 each semiconducting metal oxide and metal sulfide minerals. The relationships between energy levels at mineral … The absolute energy positions of conduction and valence band edges were compiled for about 50 each semiconducting metal oxide and metal sulfide minerals. The relationships between energy levels at mineral semiconductor-electrolyte interfaces and the activities of these minerals as a catalyst or photocatalyst in aqueous redox reactions are reviewed. The compilation of band edge energies is based on experimental flatband potential data and complementary empirical calculations from electronegativities of constituent elements. Whereas most metal oxide semiconductors have valence band edges 1 to 3 eV below the H2O oxidation potential (relative to absolute vacuum scale), energies for conduction band edges are close to, or lower than, the H2O reduction potential. These oxide minerals are strong photo-oxidation catalysts in aqueous solutions, but are limited in their reducing power. Non-transition metal sulfides generally have higher conduction and valence band edge energies than metal oxides; therefore, valence band holes in non-transition metal sulfides are less oxidizing, but conduction band electrons are exceedingly reducing. Most transition-metal sulfides, however, are characterized by small band gaps (<1 eV) and band edges situated within or close to the H2O stability potentials. Hence, both the oxidizing power of the valence band holes and the reducing power of the conduction band electrons are lower than those of non-transition metal sulfides.

The role of soft colloidal templates in controlling the size and shape of inorganic nanocrystals

2003-02-28

Marie‐Paule Pileni

Infrared Spectra of Ferrites

1955-09-15

R. D. Waldron

The infrared spectra of 7 ferrites of the formula $M{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$, where $M$ designates a divalent metal, are presented and analyzed. Electronic absorption was observed in the visible and near-infrared regions. … The infrared spectra of 7 ferrites of the formula $M{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$, where $M$ designates a divalent metal, are presented and analyzed. Electronic absorption was observed in the visible and near-infrared regions. Two absorption bands arising from interatomic vibrations were measured and force constants calculated for the stretching of bonds between octahedral or tetrahedral metal ions and oxide ions. These force constants are in agreement with the elastic and thermodynamic properties of these compounds and are sensitive to distribution of metal ions between the alternate sites. The integrated vibrational band intensities were measured: they are compatible with predominantly ionic bonding for these structures.

The interaction of water with solid surfaces: fundamental aspects revisited

2002-05-01

M Henderson

Solar Water Splitting: Progress Using Hematite (α‐Fe2O3) Photoelectrodes

2011-03-17

Kevin Sivula , Florian Le Formal , Michaël Grätzel

Abstract Photoelectrochemical (PEC) cells offer the ability to convert electromagnetic energy from our largest renewable source, the Sun, to stored chemical energy through the splitting of water into molecular oxygen … Abstract Photoelectrochemical (PEC) cells offer the ability to convert electromagnetic energy from our largest renewable source, the Sun, to stored chemical energy through the splitting of water into molecular oxygen and hydrogen. Hematite (α‐Fe 2 O 3 ) has emerged as a promising photo‐electrode material due to its significant light absorption, chemical stability in aqueous environments, and ample abundance. However, its performance as a water‐oxidizing photoanode has been crucially limited by poor optoelectronic properties that lead to both low light harvesting efficiencies and a large requisite overpotential for photoassisted water oxidation. Recently, the application of nanostructuring techniques and advanced interfacial engineering has afforded landmark improvements in the performance of hematite photoanodes. In this review, new insights into the basic material properties, the attractive aspects, and the challenges in using hematite for photoelectrochemical (PEC) water splitting are first examined. Next, recent progress enhancing the photocurrent by precise morphology control and reducing the overpotential with surface treatments are critically detailed and compared. The latest efforts using advanced characterization techniques, particularly electrochemical impedance spectroscopy, are finally presented. These methods help to define the obstacles that remain to be surmounted in order to fully exploit the potential of this promising material for solar energy conversion.

Synthesis, properties, and applications of magnetic iron oxide nanoparticles

2008-12-14

Amyn S. Teja , Pei‐Yoong Koh

Low-Field Magnetic Separation of Monodisperse Fe 3 O 4 Nanocrystals

2006-11-09

Cafer T. Yavuz , John T. Mayo , William W. Yu +7 more

Magnetic separations at very low magnetic field gradients (<100 tesla per meter) can now be applied to diverse problems, such as point-of-use water purification and the simultaneous separation of complex … Magnetic separations at very low magnetic field gradients (<100 tesla per meter) can now be applied to diverse problems, such as point-of-use water purification and the simultaneous separation of complex mixtures. High-surface area and monodisperse magnetite (Fe3O4) nanocrystals (NCs) were shown to respond to low fields in a size-dependent fashion. The particles apparently do not act independently in the separation but rather reversibly aggregate through the resulting high-field gradients present at their surfaces. Using the high specific surface area of Fe3O4 NCs that were 12 nanometers in diameter, we reduced the mass of waste associated with arsenic removal from water by orders of magnitude. Additionally, the size dependence of magnetic separation permitted mixtures of 4- and 12-nanometer-sized Fe3O4 NCs to be separated by the application of different magnetic fields.

Microdetermination of Phosphorus

1956-11-01

P. S. Chen , T. Y. Toribara , Huber R. Warner

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMicrodetermination of PhosphorusP. S. Chen, T. Y. Toribara, and Huber. WarnerCite this: Anal. Chem. 1956, 28, 11, 1756–1758Publication Date (Print):November 1, 1956Publication History Published online1 May 2002Published … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMicrodetermination of PhosphorusP. S. Chen, T. Y. Toribara, and Huber. WarnerCite this: Anal. Chem. 1956, 28, 11, 1756–1758Publication Date (Print):November 1, 1956Publication History Published online1 May 2002Published inissue 1 November 1956https://pubs.acs.org/doi/10.1021/ac60119a033https://doi.org/10.1021/ac60119a033research-articleACS PublicationsRequest reuse permissionsArticle Views6581Altmetric-Citations5821LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Quantitative Analysis of Anatase-Rutile Mixtures with an X-Ray Diffractometer

1957-05-01

Robert A. Spurr , H. P. Myers

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTQuantitative Analysis of Anatase-Rutile Mixtures with an X-Ray DiffractometerR. A. Spurr and Howard. MyersCite this: Anal. Chem. 1957, 29, 5, 760–762Publication Date (Print):May 1, 1957Publication History Published … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTQuantitative Analysis of Anatase-Rutile Mixtures with an X-Ray DiffractometerR. A. Spurr and Howard. MyersCite this: Anal. Chem. 1957, 29, 5, 760–762Publication Date (Print):May 1, 1957Publication History Published online1 May 2002Published inissue 1 May 1957https://pubs.acs.org/doi/10.1021/ac60125a006https://doi.org/10.1021/ac60125a006research-articleACS PublicationsRequest reuse permissionsArticle Views4765Altmetric-Citations1632LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Adsorption and desorption of natural organic matter on iron oxide: mechanisms and models

1994-01-01

Baohua Gu , Juergen Schmitt , Zhihong. Chen +2 more

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAdsorption and desorption of natural organic matter on iron oxide: mechanisms and modelsBaohua. Gu, Juergen. Schmitt, Zhihong. Chen, Liyuan. Liang, and John F. McCarthyCite this: Environ. Sci. … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAdsorption and desorption of natural organic matter on iron oxide: mechanisms and modelsBaohua. Gu, Juergen. Schmitt, Zhihong. Chen, Liyuan. Liang, and John F. McCarthyCite this: Environ. Sci. Technol. 1994, 28, 1, 38–46Publication Date (Print):January 1, 1994Publication History Published online1 May 2002Published inissue 1 January 1994https://pubs.acs.org/doi/10.1021/es00050a007https://doi.org/10.1021/es00050a007research-articleACS PublicationsRequest reuse permissionsArticle Views9587Altmetric-Citations1194LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Self‐Assembled 3D Flowerlike Iron Oxide Nanostructures and Their Application in Water Treatment

2006-09-12

Lu-Bin Zhong , Jin‐Song Hu , H. Liang +3 more

An ethylene-glycol-mediated self-assembly process is adopted to synthesize 3D flowerlike nanostructures of iron oxide (see figure) using inexpensive and nontoxic ferric chloride. A two-stage growth process is identified during the … An ethylene-glycol-mediated self-assembly process is adopted to synthesize 3D flowerlike nanostructures of iron oxide (see figure) using inexpensive and nontoxic ferric chloride. A two-stage growth process is identified during the morphological evolution of the iron oxide precursor. α-Fe2O3, γ-Fe2O3, and Fe3O4 with the same flowerlike structure are readily obtained from the same precursor but by different calcination procedures. The as-obtained iron oxides show excellent ability to remove various pollutants from water.

Direction-Specific Interactions Control Crystal Growth by Oriented Attachment

2012-05-24

Dongsheng Li , Michael H. Nielsen , Jonathan R. I. Lee +3 more

The oriented attachment of molecular clusters and nanoparticles in solution is now recognized as an important mechanism of crystal growth in many materials, yet the alignment process and attachment mechanism … The oriented attachment of molecular clusters and nanoparticles in solution is now recognized as an important mechanism of crystal growth in many materials, yet the alignment process and attachment mechanism have not been established. We performed high-resolution transmission electron microscopy using a fluid cell to directly observe oriented attachment of iron oxyhydroxide nanoparticles. The particles undergo continuous rotation and interaction until they find a perfect lattice match. A sudden jump to contact then occurs over less than 1 nanometer, followed by lateral atom-by-atom addition initiated at the contact point. Interface elimination proceeds at a rate consistent with the curvature dependence of the Gibbs free energy. Measured translational and rotational accelerations show that strong, highly direction-specific interactions drive crystal growth via oriented attachment.

Photoelectrochemistry and heterogeneous photo-catalysis at semiconductors

1979-01-01

Allen J. Bard

Small-particle research: physicochemical properties of extremely small colloidal metal and semiconductor particles

1989-12-01

A. Henglein

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSmall-particle research: physicochemical properties of extremely small colloidal metal and semiconductor particlesArnim HengleinCite this: Chem. Rev. 1989, 89, 8, 1861–1873Publication Date (Print):December 1, 1989Publication History Published online1 … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSmall-particle research: physicochemical properties of extremely small colloidal metal and semiconductor particlesArnim HengleinCite this: Chem. Rev. 1989, 89, 8, 1861–1873Publication Date (Print):December 1, 1989Publication History Published online1 May 2002Published inissue 1 December 1989https://pubs.acs.org/doi/10.1021/cr00098a010https://doi.org/10.1021/cr00098a010research-articleACS PublicationsRequest reuse permissionsArticle Views8795Altmetric-Citations2552LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenate

1993-05-01

Glenn A. Waychunas , Brigid A. Rea , Christopher C. Fuller +1 more

EXAFS spectra were collected on both the As and Fe K-edges from samples of two-line ferrihydrite with adsorbed (ADS) and coprecipitated (CPT) arsenate prepared over a range of conditions and … EXAFS spectra were collected on both the As and Fe K-edges from samples of two-line ferrihydrite with adsorbed (ADS) and coprecipitated (CPT) arsenate prepared over a range of conditions and arsenate surface coverages. Spectra also were collected for arsenate adsorbed on the surfaces of three FeOOH crystalline polymorphs, α (goethite), β (akaganeite), and γ (lepidocrocite), and as a free ion in aqueous: solution. Analyses of the As EXAFS show clear evidence for inner sphere bidentate (bridging) arsenate complexes on the ferrihydrite surface and on the surfaces of the crystalline FeOOH polymorphs. The bridging arsenate is attached to adjacent apices of edge-sharing Fe oxyhydroxyl octahedra. The arsenic-iron distance at the interface (3.28 ±0.01 Å) is close to that expected for this geometry on the FeOOH polymorph surfaces, but is slightly shorter on the ferrihydrite surfaces (3.25 ± 0.02 Å). Mono-dentate arsenate linkages (3.60 ± 0.03 Å) also occur on the ferrihydrite, but are not generally observed on the crystalline FeOOH polymorphs. The proportion of monodentate bonds appears largest for adsorption samples with the smallest AsFe molar ratio. In all cases the arsenate tetrahedral complex is relatively undistorted with As-O bonds of 1.66 ± 0.01 Å. Precipitation of arsenate or scorodite-like phases was not observed for any samples, all of which were prepared at a pH value of 8. The Fe EXAFS results confirm that the Fe-Fe correlations in the ferrihydrite are progressively disrupted in the CPT samples as the AsFe ratio is increased. Coherent crystallite size is probably no more than 10 Å in diameter and no Fe oxyhydroxyl octahedra corner-sharing linkages (as would be present in FeOOH polymorphs) are observed at the largest AsFe ratios. Comparison of the number and type of Fe-Fe neighbors with the topological constraints imposed by the arsenate saturation limit in the CPT samples (about 0.7 AsFe) indicates ferrihydrite units consisting mainly of Fe oxyhydroxyl octahedra arranged in short dioctahedral chains with minimal interchain linking by octahedra corners. This is consistent with an enlarged surface area and a larger proportion of sites for bidentate arsenate bonding in CPT samples as compared to the ADS samples, which saturate with arsenate at lower AsFe ratios. The latter samples have larger crystallite sizes and a definite proportion of ferric octahedra sharing corners. The ratio of corner-sharing to edge-sharing Fe oxyhydroxyl octahedra in the ADS samples, and CPT samples with small As loadings, is very similar to what would be present in very small particles of goethite or akaganeite. The difference in the polymeric structure of ADS and CPT samples at higher AsFe ratios is due to strong arsenate bidentate adsorption that poisons the surface of particles of ferrihydrite precipitated in the presence of substantial arsenate, limiting their normal crystallization, and preventing further Fe-O-Fe polymerization. If the arsenate is applied after precipitation much less adsorption occurs since polymerization has already progressed. In both ADS and CPT samples, Fe-O-Fe polymerization increases with age, though at different rates for each type of sample.

Raman microspectroscopy of some iron oxides and oxyhydroxides

1997-11-01

Dalva Lúcia Araújo de Faria , S. Venâncio Silva , Maiara de Oliveira

Hematite (α-Fe2O3), magnetite (Fe3O4), wüstite (FeO), maghemite (γ-Fe2O3), goethite (α-FeOOH), lepidocrocite (γ-FeOOH) and δ-FeOOH were studied by Raman microscopy. Such compounds have already been studied by Raman spectroscopy, but there … Hematite (α-Fe2O3), magnetite (Fe3O4), wüstite (FeO), maghemite (γ-Fe2O3), goethite (α-FeOOH), lepidocrocite (γ-FeOOH) and δ-FeOOH were studied by Raman microscopy. Such compounds have already been studied by Raman spectroscopy, but there are some disagreements in the reported data. Here, Raman microscopy was employed to investigate the laser power dependence of the spectra of these oxides and oxyhydroxides. Low laser power was used for the reference spectra in order to minimize the risks of spectral changes due to sample degradation. The results obtained show that increasing laser power causes the characteristic bands of hematite to show up in the spectra of most of the compounds studied whereas the hematite spectrum undergoes band broadening and band shifts. © 1997 John Wiley & Sons, Ltd.

Electronic Conduction of Magnetite (Fe3O4) and its Transition Point at Low Temperatures

1939-08-01

E. J. W. Verwey

Morphology development and crystal growth in nanocrystalline aggregates under hydrothermal conditions: insights from titania

1999-05-01

R. Lee Penn , Jillian F. Banfield

A Surface Structural Approach to Ion Adsorption: The Charge Distribution (CD) Model

1996-05-01

Tjisse Hiemstra , W.H. van Riemsdijk

Sn-Doped Hematite Nanostructures for Photoelectrochemical Water Splitting

2011-04-08

Yichuan Ling , Gongming Wang , Damon A. Wheeler +2 more

We report on the synthesis and characterization of Sn-doped hematite nanowires and nanocorals as well as their implementation as photoanodes for photoelectrochemical water splitting. The hematite nanowires were prepared on … We report on the synthesis and characterization of Sn-doped hematite nanowires and nanocorals as well as their implementation as photoanodes for photoelectrochemical water splitting. The hematite nanowires were prepared on a fluorine-doped tin oxide (FTO) substrate by a hydrothermal method, followed by high temperature sintering in air to incorporate Sn, diffused from the FTO substrate, as a dopant. Sn-doped hematite nanocorals were prepared by the same method, by adding tin(IV) chloride as the Sn precursor. X-ray photoelectron spectroscopy analysis confirms Sn4+ substitution at Fe3+ sites in hematite, and Sn-dopant levels increase with sintering temperature. Sn dopant serves as an electron donor and increases the carrier density of hematite nanostructures. The hematite nanowires sintered at 800 °C yielded a pronounced photocurrent density of 1.24 mA/cm2 at 1.23 V vs RHE, which is the highest value observed for hematite nanowires. In comparison to nanowires, Sn-doped hematite nanocorals exhibit smaller feature sizes and increased surface areas. Significantly, they showed a remarkable photocurrent density of 1.86 mA/cm2 at 1.23 V vs RHE, which is approximately 1.5 times higher than that of the nanowires. Ultrafast spectroscopy studies revealed that there is significant electron−hole recombination within the first few picoseconds, while Sn doping and the change of surface morphology have no major effect on the ultrafast dynamics of the charge carriers on the picosecond time scales. The enhanced photoactivity in Sn-doped hematite nanostructures should be due to the improved electrical conductivity and increased surface area.

Synthesis of Highly Crystalline and Monodisperse Maghemite Nanocrystallites without a Size-Selection Process

2001-11-29

Taeghwan Hyeon , Su Seong Lee , Jongnam Park +2 more

The synthesis of highly crystalline and monodisperse gamma-Fe(2)O(3) nanocrystallites is reported. High-temperature (300 degrees C) aging of iron-oleic acid metal complex, which was prepared by the thermal decomposition of iron … The synthesis of highly crystalline and monodisperse gamma-Fe(2)O(3) nanocrystallites is reported. High-temperature (300 degrees C) aging of iron-oleic acid metal complex, which was prepared by the thermal decomposition of iron pentacarbonyl in the presence of oleic acid at 100 degrees C, was found to generate monodisperse iron nanoparticles. The resulting iron nanoparticles were transformed to monodisperse gamma-Fe(2)O(3) nanocrystallites by controlled oxidation by using trimethylamine oxide as a mild oxidant. Particle size can be varied from 4 to 16 nm by controlling the experimental parameters. Transmission electron microscopic images of the particles showed 2-dimensional and 3-dimensional assembly of particles, demonstrating the uniformity of these nanoparticles. Electron diffraction, X-ray diffraction, and high-resolution transmission electron microscopic (TEM) images of the nanoparticles showed the highly crystalline nature of the gamma-Fe(2)O(3) structures. Monodisperse gamma-Fe(2)O(3) nanocrystallites with a particle size of 13 nm also can be generated from the direct oxidation of iron pentacarbonyl in the presence of oleic acid with trimethylamine oxide as an oxidant.

Light-Induced Redox Reactions in Nanocrystalline Systems

1995-01-01

Anders Hagfeldt , Michael Gräetzel

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLight-Induced Redox Reactions in Nanocrystalline SystemsAnders Hagfeldt and Michael GraetzelCite this: Chem. Rev. 1995, 95, 1, 49–68Publication Date (Print):January 1, 1995Publication History Published online1 May 2002Published inissue … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLight-Induced Redox Reactions in Nanocrystalline SystemsAnders Hagfeldt and Michael GraetzelCite this: Chem. Rev. 1995, 95, 1, 49–68Publication Date (Print):January 1, 1995Publication History Published online1 May 2002Published inissue 1 January 1995https://pubs.acs.org/doi/10.1021/cr00033a003https://doi.org/10.1021/cr00033a003research-articleACS PublicationsRequest reuse permissionsArticle Views20019Altmetric-Citations4837LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

New Benchmark for Water Photooxidation by Nanostructured α-Fe2O3 Films

2006-11-15

Andreas Kay , I. Cesar , Michaël Grätzel

Thin films of silicon-doped Fe2O3 were deposited by APCVD (atmospheric pressure chemical vapor deposition) from Fe(CO)5 and TEOS (tetraethoxysilane) on SnO2-coated glass at 415 °C. HRSEM reveals a highly developed … Thin films of silicon-doped Fe2O3 were deposited by APCVD (atmospheric pressure chemical vapor deposition) from Fe(CO)5 and TEOS (tetraethoxysilane) on SnO2-coated glass at 415 °C. HRSEM reveals a highly developed dendritic nanostructure of 500 nm thickness having a feature size of only 10−20 nm at the surface. Real surface area determination by dye adsorption yields a roughness factor of 21. XRD shows the films to be pure hematite with strong preferential orientation of the [110] axis vertical to the substrate, induced by silicon doping. Under illumination in 1 M NaOH, water is oxidized at the Fe2O3 electrode with higher efficiency (IPCE = 42% at 370 nm and 2.2 mA/cm2 in AM 1.5 G sunlight of 1000 W/m2 at 1.23 VRHE) than at the best reported single crystalline Fe2O3 electrodes. This unprecedented efficiency is in part attributed to the dendritic nanostructure which minimizes the distance photogenerated holes have to diffuse to reach the Fe2O3/electrolyte interface while still allowing efficient light absorption. Part of the gain in efficiency is obtained by depositing a thin insulating SiO2 interfacial layer between the SnO2 substrate and the Fe2O3 film and a catalytic cobalt monolayer on the Fe2O3 surface. A mechanistic model for water photooxidation is presented, involving stepwise accumulation of four holes by two vicinal iron or cobalt surface sites.

Shape-Dependent Catalytic Activity of Platinum Nanoparticles in Colloidal Solution

2004-05-28

Radha Narayanan , Mostafa A. El‐Sayed

The activation energies and the average rate constants are determined in the 298 K−318 K temperature range for the early stages of the nanocatalytic reaction between hexacyanoferrate (III) and thiosulfate … The activation energies and the average rate constants are determined in the 298 K−318 K temperature range for the early stages of the nanocatalytic reaction between hexacyanoferrate (III) and thiosulfate ions using 4.8 ± 0.1 nm tetrahedral, 7.1 ± 0.2 nm cubic, and 4.9 ± 0.1 nm "near spherical" nanocrystals. These kinetic parameters are found to correlate with the calculated fraction of surface atoms located on the corners and edges in each size and shape.

Water Oxidation at Hematite Photoelectrodes: The Role of Surface States

2012-02-03

Benjamin M. Klahr , Sixto Giménez , Francisco Fabregat‐Santiago +2 more

Hematite (α-Fe2O3) constitutes one of the most promising semiconductor materials for the conversion of sunlight into chemical fuels by water splitting. Its inherent drawbacks related to the long penetration depth … Hematite (α-Fe2O3) constitutes one of the most promising semiconductor materials for the conversion of sunlight into chemical fuels by water splitting. Its inherent drawbacks related to the long penetration depth of light and poor charge carrier conductivity are being progressively overcome by employing nanostructuring strategies and improved catalysts. However, the physical–chemical mechanisms responsible for the photoelectrochemical performance of this material (J(V) response) are still poorly understood. In the present study we prepared thin film hematite electrodes by atomic layer deposition to study the photoelectrochemical properties of this material under water-splitting conditions. We employed impedance spectroscopy to determine the main steps involved in photocurrent production at different conditions of voltage, light intensity, and electrolyte pH. A general physical model is proposed, which includes the existence of a surface state at the semiconductor/liquid interface where holes accumulate. The strong correlation between the charging of this state with the charge transfer resistance and the photocurrent onset provides new evidence of the accumulation of holes in surface states at the semiconductor/electrolyte interface, which are responsible for water oxidation. The charging of this surface state under illumination is also related to the shift of the measured flat-band potential. These findings demonstrate the utility of impedance spectroscopy in investigations of hematite electrodes to provide key parameters of photoelectrodes with a relatively simple measurement.

View PDF Chat

Aggregation-Based Crystal Growth and Microstructure Development in Natural Iron Oxyhydroxide Biomineralization Products

2000-08-04

Jillian F. Banfield , Susan A. Welch , Hengzhong Zhang +2 more

Crystals are generally considered to grow by attachment of ions to inorganic surfaces or organic templates. High-resolution transmission electron microscopy of biomineralization products of iron-oxidizing bacteria revealed an alternative coarsening … Crystals are generally considered to grow by attachment of ions to inorganic surfaces or organic templates. High-resolution transmission electron microscopy of biomineralization products of iron-oxidizing bacteria revealed an alternative coarsening mechanism in which adjacent 2- to 3-nanometer particles aggregate and rotate so their structures adopt parallel orientations in three dimensions. Crystal growth is accomplished by eliminating water molecules at interfaces and forming iron-oxygen bonds. Self-assembly occurs at multiple sites, leading to a coarser, polycrystalline material. Point defects (from surface-adsorbed impurities), dislocations, and slabs of structurally distinct material are created as a consequence of this growth mechanism and can dramatically impact subsequent reactivity.

The sol-gel process

1990-01-01

Larry L. Hench , Jon K. West

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe sol-gel processLarry L. Hench and Jon K. WestCite this: Chem. Rev. 1990, 90, 1, 33–72Publication Date (Print):January 1, 1990Publication History Published online1 May 2002Published inissue 1 … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe sol-gel processLarry L. Hench and Jon K. WestCite this: Chem. Rev. 1990, 90, 1, 33–72Publication Date (Print):January 1, 1990Publication History Published online1 May 2002Published inissue 1 January 1990https://pubs.acs.org/doi/10.1021/cr00099a003https://doi.org/10.1021/cr00099a003research-articleACS PublicationsRequest reuse permissionsArticle Views54674Altmetric-Citations3577LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Monodisperse α-Fe2O3 Mesoporous Microspheres: One-Step NaCl-Assisted Microwave-Solvothermal Preparation, Size Control and Photocatalytic Property

2010-08-17

Shaowen Cao , Ying‐Jie Zhu

A simple one-step NaCl-assisted microwave-solvothermal method has been developed for the preparation of monodisperse α-Fe2O3 mesoporous microspheres. In this approach, Fe(NO3)3 · 9H2O is used as the iron source, and … A simple one-step NaCl-assisted microwave-solvothermal method has been developed for the preparation of monodisperse α-Fe2O3 mesoporous microspheres. In this approach, Fe(NO3)3 · 9H2O is used as the iron source, and polyvinylpyrrolidone (PVP) acts as a surfactant in the presence of NaCl in mixed solvents of H2O and ethanol. Under the present experimental conditions, monodisperse α-Fe2O3 mesoporous microspheres can form via oriented attachment of α-Fe2O3 nanocrystals. One of the advantages of this method is that the size of α-Fe2O3 mesoporous microspheres can be adjusted in the range from ca. 170 to ca. 260 nm by changing the experimental parameters. High photocatalytic activities in the degradation of salicylic acid are observed for α-Fe2O3 mesoporous microspheres with different specific surface areas.

View PDF Chat

Light‐Induced Water Splitting with Hematite: Improved Nanostructure and Iridium Oxide Catalysis

2010-07-21

S. David Tilley , Maurin Cornuz , Kevin Sivula +1 more

Revved-up rust! Light-induced water splitting over iron oxide (hematite) has been achieved by using a particle-assisted deposition technique and IrO2-based surface catalysis. Photocurrents in excess of 3 mA cm−2 were … Revved-up rust! Light-induced water splitting over iron oxide (hematite) has been achieved by using a particle-assisted deposition technique and IrO2-based surface catalysis. Photocurrents in excess of 3 mA cm−2 were obtained at +1.23 V versus the reversible hydrogen electrode under AM 1.5 G 100 mW cm−2 simulated sunlight. These photocurrents are unmatched by any other oxide-based photoanode. FTO=fluorine-doped tin oxide. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

In situXPS analysis of various iron oxide films grown by<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">NO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>-assisted molecular-beam epitaxy

1999-01-15

Tatsuo Fujii , Frank M. F. de Groot , G. A. Sawatzky +3 more

We report on a systematic analysis of x-ray photoelectron spectroscopy (XPS) core- and valence-level spectra of clean and well-characterized iron oxide films, i.e., $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3},$ $\ensuremath{\gamma}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3},$ ${\mathrm{Fe}}_{3\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}{\mathrm{O}}_{4},$ and ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}.$ All iron … We report on a systematic analysis of x-ray photoelectron spectroscopy (XPS) core- and valence-level spectra of clean and well-characterized iron oxide films, i.e., $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3},$ $\ensuremath{\gamma}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3},$ ${\mathrm{Fe}}_{3\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}{\mathrm{O}}_{4},$ and ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}.$ All iron oxide films were prepared epitaxially by ${\mathrm{NO}}_{2}$-assisted molecular-beam epitaxy on single crystalline MgO(100) and $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}(0001)$ substrates. The phase and stoichiometry of the films were controlled precisely by adjusting the ${\mathrm{NO}}_{2}$ pressure during growth. The XPS spectrum of each oxide clearly showed satellite structures. These satellite structures were simulated using a cluster-model calculation, which could well reproduce the observed structures by considering the systematic changes in both the Fe $3d$ to O $2p$ hybridization and the $d\ensuremath{-}d$ electron-correlation energy. The small difference in the satellite structures between $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ and $\ensuremath{\gamma}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ resulted mainly from changes in the Fe-O hybridization parameters, suggesting an increased covalency in $\ensuremath{\gamma}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ compared to $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}.$ With increasing reduction in the $\ensuremath{\gamma}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}{\ensuremath{-}\mathrm{F}\mathrm{e}}_{3}{\mathrm{O}}_{4}$ system, the satellite structures in XPS became unresolved. This was not only due to the formation of ${\mathrm{Fe}}^{2+}$ ions, but also to nonhomogeneous changes in the hybridization parameters between octahedral and tetrahedral ${\mathrm{Fe}}^{3+}$ ions.

The iron oxides: Structure, properties, reactions, occurrence and uses

1997-08-01

G.T. Burstein

Metal Oxide Surfaces and Their Interactions with Aqueous Solutions and Microbial Organisms

1998-12-24

Gordon E. Brown , Victor E. Henrich , William H. Casey +7 more

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetal Oxide Surfaces and Their Interactions with Aqueous Solutions and Microbial OrganismsGordon E. Brown, Victor E. Henrich, William H. Casey, David L. Clark, Carrick Eggleston, Andrew Felmy, … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetal Oxide Surfaces and Their Interactions with Aqueous Solutions and Microbial OrganismsGordon E. Brown, Victor E. Henrich, William H. Casey, David L. Clark, Carrick Eggleston, Andrew Felmy, D. Wayne Goodman, Michael Grätzel, Gary Maciel, Maureen I. McCarthy, Kenneth H. Nealson, Dimitri A. Sverjensky, Michael F. Toney, and John M. ZacharaView Author Information Surface and Aqueous Geochemistry Group, Department of Geological & Environmental Sciences, Stanford University, Stanford, California 94305-2115 Surface Science Laboratory, Department of Applied Physics, Yale University, New Haven, Connecticut 06520 Department of Land, Air, and Water Resources, University of California, Davis, Davis, California 95616 G.T. Seaborg Institute for Transactinium Science, Nuclear Materials Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming 82071-3006 Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255 Institute of Chemical Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland Department of Chemistry, Colorado State University, Ft. Collins, Colorado 80523 Theory, Modeling and Simulation Group, Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 Jet Propulsion Laboratory-183-301, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109-8099 Department of Earth and Planetary Sciences, The Johns Hopkins University, Baltimore, Maryland 21218 IBM Almaden Research Center, San Jose, California 95120 Environmental Molecular Sciences, Laboratory Pacific Northwest National Laboratory, Richland, Washington 99352 Cite this: Chem. Rev. 1999, 99, 1, 77–174Publication Date (Web):December 24, 1998Publication History Received27 February 1998Revised9 November 1998Published online24 December 1998Published inissue 13 January 1999https://pubs.acs.org/doi/10.1021/cr980011zhttps://doi.org/10.1021/cr980011zresearch-articleACS PublicationsCopyright © 1999 American Chemical SocietyRequest reuse permissionsArticle Views9915Altmetric-Citations894LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Adsorption,Interfaces,Ions,Metals,Oxides Get e-Alerts

View PDF Chat

A general equation for estimating Fe3+ concentrations in ferromagnesian silicates and oxides from microprobe analyses, using stoichiometric criteria

1987-09-01

G. T. R. Droop

Abstract A simple general equation is presented for estimating the Fe 3+ concentrations in ferromagnesian oxide and silicate minerals from microprobe analyses. The equation has been derived using stoichiometric criteria … Abstract A simple general equation is presented for estimating the Fe 3+ concentrations in ferromagnesian oxide and silicate minerals from microprobe analyses. The equation has been derived using stoichiometric criteria assuming that iron is the only element present with variable valency and that oxygen is the only anion. In general, the number of Fe 3+ ions per X oxygens in the mineral formula, F , is given by; where T is the ideal number of cations per formula unit, and S is the observed cation total per X oxygens calculated assuming all iron to be Fe 2+ . Minerals for which this equation is appropriate include pyralspite and ugrandite garnet, aluminate spinel, magnetite, pyroxene, sapphirine and ilmenite. The equation cannot be used for minerals with cation vacancies (e.g. micas, maghemite) unless, as in the case of amphiboles, the number of ions of a subset of elements in the formula can be fixed. Variants of the above equation are presented for some of the numerous published schemes for the recalculation of amphibole formulae. The equation is also inappropriate for minerals showing Si 4+ = 4H + substitution (e.g. staurolite, hydrogarnet), minerals containing an unknown proportion of an unanalysed element other than oxygen (e.g. boron-bearing kornerupine) and minerals containing two or more elements with variable valency.

Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

2008-10-01

Wei Wu , Quanguo He , Changzhong Jiang

Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent … Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed.

View PDF Chat

Chemical synthesis of magnetic nanoparticles

2002-12-03

Taeghwan Hyeon

Recent advances in the synthesis of various magnetic nanoparticles using colloidal chemical approaches are reviewed. Typically, these approaches involve either rapid injection of reagents into hot surfactant solution followed by … Recent advances in the synthesis of various magnetic nanoparticles using colloidal chemical approaches are reviewed. Typically, these approaches involve either rapid injection of reagents into hot surfactant solution followed by aging at high temperature, or the mixing of reagents at a low temperature and slow heating under controlled conditions. Spherical cobalt nanoparticles with various crystal structures have been synthesized by thermally decomposing dicobalt octacarbonyl or by reducing cobalt salts. Nanoparticles of Fe-Pt and other related iron or cobalt containing alloys have been made by simultaneously reacting their constituent precursors. Many different ferrite nanoparticles have been synthesized by the thermal decomposition of organometallic precursors followed by oxidation or by low-temperature reactions inside reverse micelles. Rod-shaped iron nanoparticles have been synthesized from the oriented growth of spherical nanoparticles, and cobalt nanodisks were synthesized from the thermal decomposition of dicobalt octacarbonyl in the presence of a mixture of two surfactants.

Iron-Titanium Oxide Minerals and Synthetic Equivalents

1964-01-01

A. F. Buddington , D. H. Lindsley

Journal Article Iron-Titanium Oxide Minerals and Synthetic Equivalents Get access A. F. BUDDINGTON, A. F. BUDDINGTON Search for other works by this author on: Oxford Academic Google Scholar D. H. … Journal Article Iron-Titanium Oxide Minerals and Synthetic Equivalents Get access A. F. BUDDINGTON, A. F. BUDDINGTON Search for other works by this author on: Oxford Academic Google Scholar D. H. LINDSLEY D. H. LINDSLEY Search for other works by this author on: Oxford Academic Google Scholar Journal of Petrology, Volume 5, Issue 2, 1964, Pages 310–357, https://doi.org/10.1093/petrology/5.2.310 Published: 01 June 1964

A Theory for the Estimation of Surface and Interfacial Energies. I. Derivation and Application to Interfacial Tension

1957-07-01

L. A. Girifalco , Robert J. Good

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA Theory for the Estimation of Surface and Interfacial Energies. I. Derivation and Application to Interfacial TensionL. A. Girifalco and R. J. GoodCite this: J. Phys. Chem. … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA Theory for the Estimation of Surface and Interfacial Energies. I. Derivation and Application to Interfacial TensionL. A. Girifalco and R. J. GoodCite this: J. Phys. Chem. 1957, 61, 7, 904–909Publication Date (Print):July 1, 1957Publication History Published online1 May 2002Published inissue 1 July 1957https://doi.org/10.1021/j150553a013RIGHTS & PERMISSIONSArticle Views8080Altmetric-Citations1136LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (710 KB) Get e-Alerts

Propriétés magnétiques des ferrites ; ferrimagnétisme et antiferromagnétisme

1948-01-01

M. Louis Néel

ré se n te le s figu re s 7N o u ré se n te le s figu re s 7N o u

View PDF Chat

Iron Oxide Removal from Soils and Clays by a Dithionite-Citrate System Buffered with Sodium Bicarbonate

1958-02-01

O. P. Mehra , M. L. Jackson

Abstract The oxidation potential of dithionite (Na 2 S 2 O 4 ) increases from 0.37 V to 0.73 V with increase in pH from 6 to 9, because hydroxyl … Abstract The oxidation potential of dithionite (Na 2 S 2 O 4 ) increases from 0.37 V to 0.73 V with increase in pH from 6 to 9, because hydroxyl is consumed during oxidation of dithionite. At the same time the amount of iron oxide dissolved in 15 minutes falls off (from 100 percent to less than 1 percent extracted) with increase in pH from 6 to 12 owing to solubility product relationships of iron oxides. An optimum pH for maximum reaction kinetics occurs at approximately pH 7.3. A buffer is needed to hold the pH at the optimum level because 4 moles of OH are used up in reaction with each mole of Na 2 S 2 O 4 oxidized. Tests show that NaHCO 3 effectively serves as a buffer in this application. Crystalline hematite dissolved in amounts of several hundred milligrams in 2 min. Crystalline goethite dissolved more slowly, but dissolved during the two or three 15 min treatments normally given for iron oxide removal from soils and clays. A series of methods for the extraction of iron oxides from soils and clays was tested with soils high in free iron oxides and with nontronite and other iron-bearing clays. It was found that the bicarbonate-buffered Na 2 S 2 O 4 -citrate system was the most effective in removal of free iron oxides from latosolic soils, and the least destructive of iron silicate clays as indicated by least loss in cation exchange capacity after the iron oxide removal treatment. With soils the decrease was very little but with the very susceptible Woody district nontronite, the decrease was about 17 percent as contrasted to 35–80 percent with other methods.

Large clusters and colloids. Metals in the embryonic state

1992-12-01

Guenter Schmid

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLarge clusters and colloids. Metals in the embryonic stateGuenter SchmidCite this: Chem. Rev. 1992, 92, 8, 1709–1727Publication Date (Print):December 1, 1992Publication History Published online1 May 2002Published inissue … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLarge clusters and colloids. Metals in the embryonic stateGuenter SchmidCite this: Chem. Rev. 1992, 92, 8, 1709–1727Publication Date (Print):December 1, 1992Publication History Published online1 May 2002Published inissue 1 December 1992https://pubs.acs.org/doi/10.1021/cr00016a002https://doi.org/10.1021/cr00016a002research-articleACS PublicationsRequest reuse permissionsArticle Views8546Altmetric-Citations1761LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Synthesis and Characterization of Nanometer-Size Fe3O4 and γ-Fe2O3 Particles

1996-01-01

Young Soo Kang , Subhash H. Risbud , John F. Rabolt +1 more

Synthesis of suspensions of nanosize particles of Fe3O4 was carried out in bulk aqueous solutions without the presence of surfactants. The Fe3O4 nanoparticles were oxidized to γ-Fe2O3 by direct aeration … Synthesis of suspensions of nanosize particles of Fe3O4 was carried out in bulk aqueous solutions without the presence of surfactants. The Fe3O4 nanoparticles were oxidized to γ-Fe2O3 by direct aeration of the suspension at 100 °C. The shape and size distribution and crystallinity of the Fe3O4 nanoparticles were assessed by transmission electron microscopy and selected area electron diffraction. Very uniform and stable colloidal suspensions of the Fe3O4 nanoparticles in water could be synthesized. Oxidation of the colloidal system leads to γ-Fe2O3 nanoparticles of much larger size than Fe3O4.

Interacting Particle Systems

1985-01-01

Thomas M. Liggett

Fumed silica-coated magnetic particles: DNA extraction application

2025-06-25

Stanley Evander Emeltan Tjoa , Mudasir Mudasir , Edi Suharyadi +1 more | Studia Universitatis Babeş-Bolyai Biologia

Tetraethyl orthosilicate (TEOS) is widely used for preparing magnetic particles in DNA extraction kits, but it poses toxicity and safety concerns. To address this issue, we developed magnetic particles using … Tetraethyl orthosilicate (TEOS) is widely used for preparing magnetic particles in DNA extraction kits, but it poses toxicity and safety concerns. To address this issue, we developed magnetic particles using fumed silica as a safer alternative to TEOS for magnetite particle preparation for DNA extraction. The method effectively extracts DNA from various biological matrices, including urine, serum, saliva, sputum, whole blood, and plasma, without detectable inhibitors. The extracted DNA is suitable for downstream molecular applications such as qPCR and sequencing. The proposed magnetic particles with fumed silica not only reduce chemical hazards but also provide a safer, efficient, and reliable method for routine DNA extraction in molecular biology laboratories. Article history: Received 15 January 2025; Revised 03 March 2025;Accepted 11 March 2025; Available online 25 June 2025

Atomistic Modeling of Functionalized Magnetite Surfaces with Oxidation States

2025-06-24

Emre Gürsoy , Robert H. Meißner , Gregor B. Vonbun-Feldbauer | The Journal of Physical Chemistry Letters

Understanding the atomic structure of magnetite-carboxylic acid interfaces is crucial for tailoring nanocomposites involving this interface. We present a Monte Carlo (MC)-based method utilizing iron oxidation state exchange to model … Understanding the atomic structure of magnetite-carboxylic acid interfaces is crucial for tailoring nanocomposites involving this interface. We present a Monte Carlo (MC)-based method utilizing iron oxidation state exchange to model magnetite interfaces with tens of thousands of atoms, scales typically inaccessible by electronic structure calculations. Charge neutrality is ensured by the oxidation of Fe ions. The MC approach allows magnetite to adapt to its environment at interfaces without requiring interface-specific rescaling of force-field parameters. This enables a simple, versatile method. By comparing adsorption sites, layer distances, and bond lengths with results from electronic structure calculations and experiments, we validated the accuracy of our method. We found that the oxidation state distribution and, consequently, binding site preference depend on coverage and surface thickness, with a critical thickness signaling the transition from layered to bulk-like oxidation states. The method ensures seamless compatibility with popular biomolecular force fields providing transferability and simplifying the study of magnetite interfaces in general.

Quantitative prediction and mechanistic insights into Cu(II) transport in kaolinite-coated sand columns affected by ferrihydrite nanoparticles

2025-06-23

Lijuan Zeng , Guining Lu , Feng Jiang +7 more | Journal of Hazardous Materials

Novel scalable mesoporous silica-assisted synthesis of high-quality ε-Fe2O3 nanoparticles revealing extraordinarily high coercivity

2025-06-20

Zdenka Medříková , Viktorie Víchová , Josef Kašlík +2 more | Materials Today Chemistry

Short-Chain Carboxylic Acids Influencing Mineralization Mechanisms of Ferrihydrite Transformation to Hematite and Goethite

2025-06-17

Xiaofan Pan , Xin Huang , Ning Deng | Environmental Science & Technology

Transformation of poorly ordered ferrihydrite (Fh) into crystalline phases controls nutrient and contaminant transport. This process is strongly influenced by organic compounds; however, the mechanism remains unclear due to the … Transformation of poorly ordered ferrihydrite (Fh) into crystalline phases controls nutrient and contaminant transport. This process is strongly influenced by organic compounds; however, the mechanism remains unclear due to the structural complexity of organic compounds, particularly carboxylic density. We selected well-defined short-chain organic acids (OAc), i.e., formic acid (FA), oxalic acid (Ox), and citric acid (CA), which commonly occur as components of organic compounds, to examine how carboxylic density influences Fh transformation. Results showed that Fh transformation was mediated by specific organic-mineral/ion interactions. Monocarboxylic FA exhibited minimal binding affinity and thus had negligible influence on Fh transformation. In contrast, dicarboxylic Ox interacted with Fh and dissolved Fe3+, accelerating Fh dissolution by destabilizing Fe-O bonds of Fh and lowering aqueous Fe3+ activity. During subsequent nucleation, Ox preferentially adsorbed onto nascent hematite (Hm) nuclei via bidentate-mononuclear complexation. This interaction reduced Hm surface energy from 330 to 180 mJ·m-2, increasing nucleation rate ∼70-fold compared to goethite (Gt). Moreover, Ox likely guided Hm growth via oriented attachment, probably driven by van der Waals forces and/or patch-charge attraction. Conversely, tricarboxylic CA strongly bound to Fh, stabilizing Fh against transformation. This study offers mineralization perspectives for understanding organic-mediated Fh transformation in environmental and engineered systems.

Pore-Size-Dependent Kinetics and Product Distribution of Fe(II)-Catalyzed Ferrihydrite Transformation

2025-06-17

Linxin Cheng , Yuefei Ding , Yuanyuan Liu +5 more | Environmental Science & Technology

Fe(II)-catalyzed ferrihydrite (Fh) transformation is a widely occurring biogeochemical process in the porous media of anaerobic soils and sediments, but how pore-scale spaces affect the kinetics and product distribution of … Fe(II)-catalyzed ferrihydrite (Fh) transformation is a widely occurring biogeochemical process in the porous media of anaerobic soils and sediments, but how pore-scale spaces affect the kinetics and product distribution of Fh transformation remains poorly understood. This study investigated the transformation of Fh nanoparticle film across a continuum of sizes of pore-scale spaces created by pressing a glass bead onto the film and immersing in 2 mM and 10 mM FeSO4 at pH = 7.0. While lepidocrocite (Lp) dominated over goethite (Gt) on the static Fh film, both minerals were observed to preferentially precipitate in micropore regions adjacent to the Fh film-glass bead contact area. The natural logarithm of product formation rates decreased linearly as increasing pore height (h) from 5 to 600 μm, revealing pronounced kinetic inhibition in macropore regions. Product mineral particles in smaller pore regions exhibited reduced primary particle size (146.1 ± 57.6 nm at h = 0.11 μm) compared with those in larger pores (222.5 ± 61.8 nm at h = 561.84 μm). COMSOL-based reaction-diffusion modeling shows that rapid Fe(III)labile intermediate supply from Fe(II)-catalyzed Fh dissolution drives its localized accumulation and elevated supersaturation within confined micropores, which ultimately dictates the pore-size-dependent distribution, formation kinetics, and primary particle size of the resulting product minerals. These findings provide mechanistic insights into the dominant role of intermediate precursor supply in dictating confinement-regulated phase transformation and highlight the notable effects of micropore size on Fh transformation and element cycling in natural porous media.

Water Nanofilms Mediate Adhesion and Heat Transfer at Hematite‐Hydrocarbon Interfaces

2025-06-17

Fionn Carman , Fernando Bresme , Billy Wu +2 more | Advanced Materials Interfaces

Abstract A detailed understanding of nanoscale heat transport at metal oxide‐hydrocarbon interfaces is critical for many applications that require efficient thermal management. Under ambient conditions, water nanofilms are expected to … Abstract A detailed understanding of nanoscale heat transport at metal oxide‐hydrocarbon interfaces is critical for many applications that require efficient thermal management. Under ambient conditions, water nanofilms are expected to form at these interfaces, but these are rarely accounted for in simulations. Using molecular dynamics simulations, it is shown that water nanofilms at the hydroxylated hematite/poly‐α‐olefin (PAO) interface significantly affect wettability and thermal transport. Including water nanofilms improves agreement with experimental work of adhesion, which cannot be replicated with anhydrous systems using realistic solid–liquid interactions. For water films thicker than one monolayer, interfacial thermal resistance (ITR) converges to a consistent value, independent of solid–liquid interaction strength. This value is dominated by the ITR at the water/PAO interface. The ITR at the water/PAO interface is dependent on the surface area between the water film and the PAO and the magnitude of the interfacial potential. These simulations provide a more precise estimate of ITR at the hematite/PAO interface by accounting for surface hydration expected in experiments under ambient conditions. This study offers crucial insights into the roles of surface hydroxylation and water nanofilms in controlling wettability and thermal transport at industrially important interfaces.

Insight into the fate of CdSe quantum dots during ferrihydrite-humic acid co-precipitation: Changes in distribution and bioavailability of quantum dots

2025-06-17

Weiyu Liang , Cheng Peng , Chengpeng Su +4 more | Chemical Engineering Journal

Accelerated Recombination Reaction through Interfacial FeIV=O Accumulation on Photoanode Surfaces

2025-06-13

Jingguo Li , Hang Chen , Siqin Liu +6 more | Journal of the American Chemical Society

The observation of third-order water oxidation kinetics by FeIV=O accumulation at the semiconductor-electrolyte interface is a milestone for understanding the four-electron transfer reaction mechanism. However, the consequences of such FeIV=O … The observation of third-order water oxidation kinetics by FeIV=O accumulation at the semiconductor-electrolyte interface is a milestone for understanding the four-electron transfer reaction mechanism. However, the consequences of such FeIV=O accumulation for the associated recombination reaction kinetics at the interface have not been fully explored so far. Here, we observe fast second-order recombination reaction kinetics for FeIV=O as the result of its accumulation at the model hematite-electrolyte interface, compared to the first-order recombination reaction kinetics for a lesser amount of available FeIV=O. We refer to this phenomenon as "accumulation-accelerated recombination (AAR)" and highlight the adverse role of FeIV=O accumulation at the interface. Further, we demonstrate that this fast second-order AAR could be slowed down to first-order kinetics by (i) deprotonation of the metal oxide surface; (ii) evacuating the conduction band electrons; and (iii) partial substitution of FeIV=O with less active CoIV=O species. Such an insight is vital not only for understanding the efficiency loss mechanisms at the semiconductor-electrolyte interface but also for interpreting the interfacial behavior of photovoltaic systems and photocatalysts.

Phase transformation of hematite to magnetite during CO reduction: Experimental and DFT-assisted insights

2025-06-13

Yuchao Qiu , Yongsheng Sun , Yuexin Han +1 more | Minerals Engineering

Site-Resolved Near-Surface Cation Diffusion in Magnetite

2025-06-13

Steffen Tober , Jan‐Christian Schober , Marcus Creutzburg +7 more | Physical Review Letters

nuclear forward scattering shows a thermally induced cation exchange between a <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mrow><a:mmultiscripts><a:mrow><a:mi>Fe</a:mi></a:mrow><a:mprescripts/><a:none/><a:mrow><a:mn>57</a:mn></a:mrow></a:mmultiscripts></a:mrow><a:mrow><a:mn>3</a:mn></a:mrow></a:msub><a:msub><a:mi mathvariant="normal">O</a:mi><a:mn>4</a:mn></a:msub></a:math> thin-film and a <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:msub><d:mi>Fe</d:mi><d:mn>3</d:mn></d:msub><d:msub><d:mi mathvariant="normal">O</d:mi><d:mn>4</d:mn></d:msub></d:math> (001) substrate predominantly in the octahedral sublattice for … nuclear forward scattering shows a thermally induced cation exchange between a <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mrow><a:mmultiscripts><a:mrow><a:mi>Fe</a:mi></a:mrow><a:mprescripts/><a:none/><a:mrow><a:mn>57</a:mn></a:mrow></a:mmultiscripts></a:mrow><a:mrow><a:mn>3</a:mn></a:mrow></a:msub><a:msub><a:mi mathvariant="normal">O</a:mi><a:mn>4</a:mn></a:msub></a:math> thin-film and a <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:msub><d:mi>Fe</d:mi><d:mn>3</d:mn></d:msub><d:msub><d:mi mathvariant="normal">O</d:mi><d:mn>4</d:mn></d:msub></d:math> (001) substrate predominantly in the octahedral sublattice for a temperature range between 470 and 710 K. The overall activation barrier in this temperature range is found to be <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mrow><g:mn>19</g:mn><g:mo>±</g:mo><g:mn>32</g:mn><g:mtext> </g:mtext><g:mtext> </g:mtext><g:mi>kJ</g:mi><g:mo>/</g:mo><g:mi>mol</g:mi></g:mrow></g:math>, which is significantly lower than expected from extrapolating a bulk diffusion model. This observation can be attributed to the large out-of-equilibrium cation deficit as determined by surface x-ray diffraction. Despite the relatively low hopping barrier, the diffusion constant is about 5 orders of magnitude lower than expected for magnetite having an equilibrium cation stoichiometry. The results are relevant for applications relying on the near-surface structure and stoichiometry of magnetite, and we argue that the correlation between cation diffusion and stoichiometry may play a role for a wider range of oxide materials. Published by the American Physical Society 2025

Short-Term Inhibition and Long-Term Enhancement of Irreversible Trace Metal Binding to Goethite in Multi-Metal Systems

2025-06-12

Greg Ledingham , Andrew T. Custis , Yihang Fang +1 more | Environmental Science & Technology

Iron (oxyhydr)oxide minerals are important sorbents of trace metals in aquatic environments. Adsorption-desorption hysteresis has been documented for trace metals after aging, suggesting that they become incorporated over time. We … Iron (oxyhydr)oxide minerals are important sorbents of trace metals in aquatic environments. Adsorption-desorption hysteresis has been documented for trace metals after aging, suggesting that they become incorporated over time. We previously found that ion size controls the extent of irreversible metal binding of single metals to goethite. In this study, we evaluate how the presence of multiple metals influences irreversible binding. Mixed Ni-Zn and Ni-Cd solutions were aged with goethite at pH 7 for 2 days, 30 days, and 60 days, after which isotope exchange experiments were performed to assess the lability of the adsorbed metal pools. After 2 days of aging, Ni and Cd in mixed-metal systems were more labile than in single-metal systems, indicating that competitive adsorption may partially block irreversible binding on short time scales. After 60 days, all three metals had larger irreversibly bound fractions than in single-metal systems. X-ray absorption near-edge structure (XANES) spectroscopy indicates that irreversibly bound fractions correlate with incorporation into goethite. This study demonstrates that pools of coadsorbed metals are bioaccessible on a time scale of minutes. Cooperative effects promote the structural sequestration of even large trace metals, causing reactive transport models to likely overpredict metal mobility. Long-term metal entrapment processes hinder micronutrient availability, impact contaminant sequestration and critical mineral recovery, and yield complex pathways through which metal solubilization may be enhanced or hindered during redox cycling.

Enhanced Organic Matter Sequestration and Phosphate Adsorption by Fe Oxides Generated from Abiotic Fe(II) Oxidation in the Presence of Heavy Metals

2025-06-06

Donglei Zhang , Xiaolei Liu , Hailiang Dong | Environmental Science & Technology

Fe(II) oxidation-precipitation affects the fate of organic matter (OM) and nutrients in soils/sediments, but the effects of commonly coexisting heavy metals (HMs) remain understudied. Herein, we investigated the individual and … Fe(II) oxidation-precipitation affects the fate of organic matter (OM) and nutrients in soils/sediments, but the effects of commonly coexisting heavy metals (HMs) remain understudied. Herein, we investigated the individual and combined effects of HMs and OM on Fe(II) oxidation-precipitation at neutral pH, along with the associated HM and organic matter sequestration, as well as phosphorus adsorption by the resultant Fe oxides. Various HMs exerted different influences on Fe(II) oxidation, which were attributed to their intrinsic properties, such as hydrolysis constant, ionic charge, and radius. Specifically, Cu(II) or Cr(III) accelerated Fe(II) oxidation and facilitated the formation of poorly crystalline Fe oxides, with the rate of acceleration depending on their concentrations, whereas Mn(II), Co(II), Ni(II), or Zn(II) showed negligible effects. Meanwhile, the sequestration efficiency of HMs followed the trend of Cr(III) > Zn(II) > Cu(II) > Co(II) > Ni(II) > Mn(II). Either Cu(II) or Cr(III) enhanced organic matter sequestration via promoting aggregation of Fe-OM associations. Fe oxides generated in the presence of Cu(II), Cr(III), and/or OM exhibited elevated phosphate adsorption due to their small particle sizes. Our results highlight the previously underappreciated importance of HMs on Fe(II) oxidation and their potential effects on carbon and phosphate retention, which should be considered in predictive models of organic matter and phosphate sequestration.

Green synthesis of hematite nano flakes and their application as a counter electrode in dye-sensitized solar cells

2025-06-05

Emma Panzi Mukhokosi , Emmanuel Mushebo , Stella Nassejje +3 more | Scientific Reports

Versatile X-ray reflector extension setup for grazing-incidence experiments at SAXS facilities for liquid surface study

2025-06-02

Andrei Chumakov , Jan Rubeck , Matthias Schwartzkopf | Journal of Synchrotron Radiation

Existing beamlines for in situ grazing-incidence small-angle scattering on liquids are either limited in angular range or incompatible with the large sample–detector distance required for submicrometre resolution. We present a … Existing beamlines for in situ grazing-incidence small-angle scattering on liquids are either limited in angular range or incompatible with the large sample–detector distance required for submicrometre resolution. We present a low-cost, easily assembled beam-tilting extension for synchrotron-based ultra-small-angle X-ray scattering (USAXS) facilities, enabling grazing-incidence and transmitted scattering (GIUSAXS, GTUSAXS) studies on liquid surfaces. The setup is compatible with standard USAXS beamlines and requires only ∼0.5 m of additional space at the sample stage. It allows X-ray beam incidence angles of up to ∼0.6° at the liquid surface, equal to twice the angle of incidence on a reflector and below its critical angle of typical materials ( e.g. silicon, germanium, etc .), and provides access to a q -range of approximately 0.003–0.5 nm −1 . The system was tested at P03 beamline (DESY) using polystyrene nanoparticles (∼197 nm) self-assembled at the air/water interface. The recorded GIUSAXS and GTSAXS patterns revealed features characteristic of near-surface hexagonally ordered monolayers and multilayer assemblies, validating the system's resolution and sensitivity. The proposed scheme enables selective depth profiling and expands the research capabilities of existing small-angle X-ray scattering synchrotron facilities for in situ studyies of submicrometre nanostructured objects at liquid surfaces under grazing-incidence geometry, while remaining fully compatible with complementary techniques such as grazing-incidence wide-angle scattering and total reflection X-ray fluorescence.

Fast synthesis of biocompatible iron oxide nanoparticles via a microwave-assisted Schikorr reaction: phase-director influence of iron glycinate complexes

2025-06-01

Antonio Santana‐Otero , Carlos Frade-González , M. Ramı́rez-del-Solar +1 more | Journal of Alloys and Compounds

pH-Dependent Release of Goethite-bound Phosphate by Biochar-Derived DOM: Non-negligible Role of Aromatic Nitrogen and Highly Unsaturated Sulfur Compounds

2025-06-01

Shujie Hu , Yuan Liu , Meng-Yue Zhang +5 more | Water Research

MAGNETIC RECOVERABLE COBALT FERRITE NANOPHOTOCATALYST FOR CRYSTAL VIOLET DYE DEGRADATION

2025-06-01

Yu Shi Lee , Kian Mun Lee , Boon Hoong Ong | Ceramics International

Construction of NiFeCoOOH/Fe2O3 Heterojunction Photoanodes for Photoelectrochemical Water Oxidation

2025-06-01

Lingling Bi , Yiyao Zhu , Yang Sun +5 more | ChemistrySelect

Abstract Photoelectrochemical (PEC) water oxidation is pivotal for solar‐to‐chemical energy conversion, yet its efficiency remains constrained by sluggish charge transfer and high electron‐hole recombination rates in photoanodes. In this study, … Abstract Photoelectrochemical (PEC) water oxidation is pivotal for solar‐to‐chemical energy conversion, yet its efficiency remains constrained by sluggish charge transfer and high electron‐hole recombination rates in photoanodes. In this study, we reported the construction of NiFeCoOOH/Fe 2 O 3 heterojunction photoanodes via a simple drop‐coating method to boost PEC performance. The optimized NiFeCoOOH/Fe 2 O 3 ‐5 sample exhibits a photocurrent density of 0.637 mA/cm 2 at 1.23 V versus RHE, doubling that of pure Fe 2 O 3 . Structural and morphological characterizations including SEM, XPS, and XRD confirm the successful formation of the heterostructure, where NiFeCoOOH nanolayers are uniformly anchored onto Fe 2 O 3 nanorods. Electrochemical analyses (EIS, Mott–Schottky, and OCP) reveal that the heterojunction significantly promotes photogenerated charge separation and suppresses recombination, primarily attributed to the built‐in electric field at the interface. Reduced impedance and altered flat‐band potential verifying improved charge transfer kinetics and increased carrier concentration. This work demonstrates that integrating trimetallic NiFeCoOOH with Fe 2 O 3 via heterostructure engineering represents an effective strategy to enhance PEC water oxidation, providing a promising strategy for designing high‐performance iron‐based photoanodes in renewable energy applications.

Microbial transformation of Fenton sludge to crystalline iron minerals with fermentation-derived phosphorous for heavy metal immobilization

2025-06-01

Han Li , Zhangyi Xu , Tsung‐Yi Chen +5 more | Journal of Hazardous Materials

Iron mineral formation using chiton-derived ferritins

2025-06-01

Songjie Du , J. J. Liao , Dawei Sun +1 more | Comparative Biochemistry and Physiology Part B Biochemistry and Molecular Biology

Potassium-Mediated Defects Enhance Energy Generation Efficiency of α-Fe2O3 Hydroelectric Cell

2025-06-01

Anoop Singh , Himanshu Tanwar , Sujata Sanghi +3 more | Ceramics International

Heterogeneous doping of metastable β-Fe2O3 thin film photoanodes for enhanced solar water splitting

2025-06-01

Kumaraswamy Miriyala , Alexander Rashkovskiy , Alexander Upcher +2 more | Applied Surface Science

The Adsorption Behavior of Cd at the Iron-Clay Mineral Interface Simulated by the Surface Complexation Model with Component Addition

2025-06-01

Yuncheng Du , Li Mei , Yun An +3 more | Deleted Journal

Cobalt-doped ferrihydrite with silicon content for efficient decomposition of ozone under dry and humid conditions

2025-05-31

Qi Shao , Mengyun Yang , Xu Chu +2 more | Journal of the Taiwan Institute of Chemical Engineers

Cation-Mediated Pseudocapacitance Dominates the Interfacial Charging of α-Fe2O3(0001) in an Alkaline Electrolyte

2025-05-30

Jordy J. J. Eggebeen , Marc T. M. Koper | The Journal of Physical Chemistry C

The electric double-layer at the electrode-electrolyte interface is crucial for electrocatalytic reactions in electrochemical applications, such as water splitting. On metal oxide surfaces in aqueous electrolytes, such as α-Fe2O3(0001), proton … The electric double-layer at the electrode-electrolyte interface is crucial for electrocatalytic reactions in electrochemical applications, such as water splitting. On metal oxide surfaces in aqueous electrolytes, such as α-Fe2O3(0001), proton exchange between interfacial water and surface groups (e.g., Fe-O-(H)) varies with pH and potential. This process induces pseudocapacitive charging alongside standard double-layer charging. Using impedance spectroscopy, the effect of cation concentration and pH on the adsorption pseudocapacitance originating from deprotonation of Fe-O-(H) was studied. Results show that both the double-layer capacitance and adsorption pseudocapacitance remain largely unaffected by the electrolyte concentration and pH within the 'double-layer' window. However, the charge transfer resistance (R ct) was found to be inversely proportional to the NaOH concentration but remained constant between pH 12 and 14 at a fixed Na+ concentration. The concentration-independent double-layer capacitance suggests a Helmholtz or compact-type layer, with negligible diffuse layer contributions to the capacitance. Consequently, no diffuse layer effects are expected on the reaction kinetics, whether pseudocapacitive or Faradaic. Interestingly, the correlation between cation concentration and R ct implies that cations mediate the proton-coupled electron transfer (PCET) acid-base reactions. This results in a cation-coupled PCET (CCPCET) mechanism that determines the current in the 'double-layer' window. Thus, the observed current in the 'double-layer' window of α-Fe2O3(0001) is predominantly cation-mediated and pseudocapacitive rather than attributable to traditional double-layer charging.

A Density Functional Theory Modeling Investigation into the Reaction Mechanisms of Ammonia Reduction of Iron Oxide Represented by the Fe2O3 (001) Surface

2025-05-29

Huanran Wang , Zhezi Zhang , Chiemeka Onyeka Okoye +2 more | Industrial & Engineering Chemistry Research

Mixing of zeolite facilitates re-sequestration of heavy metals via generated Fe-(oxyhydr)oxides in sediments in the presence of NO3- compared to capping

2025-05-01

Gen Li , Tong Cheng , Xinpeng Wang +2 more | Journal of Hazardous Materials