Identification of highly active Fe sites in (Ni,Fe)OOH for electrocatalytic water splitting.

Highly active catalysts for the oxygen evolution reaction (OER) are required for the development of photoelectrochemical devices that generate hydrogen efficiently from water using solar energy. Here, we identify the origin of a 500-fold OER activity enhancement that can be achieved with mixed (Ni,Fe)oxyhydroxides (Ni(1-x)Fe(x)OOH) over their pure Ni and Fe parent compounds, resulting in one of the most active currently known OER catalysts in alkaline electrolyte. Operando X-ray absorption spectroscopy (XAS) using high energy resolution fluorescence detection (HERFD) reveals that Fe(3+) in Ni(1-x)Fe(x)OOH occupies octahedral sites with unusually short Fe-O bond distances, induced by edge-sharing with surrounding [NiO6] octahedra. Using computational methods, we establish that this structural motif results in near optimal adsorption energies of OER intermediates and low overpotentials at Fe sites. By contrast, Ni sites in Ni(1-x)Fe(x)OOH are not active sites for the oxidation of water.

[1]  D. Sokaras,et al.  A seven-crystal Johann-type hard x-ray spectrometer at the Stanford Synchrotron Radiation Lightsource. , 2013, The Review of scientific instruments.

[2]  J. Kitchin,et al.  Spectroscopic Characterization of Mixed Fe–Ni Oxide Electrocatalysts for the Oxygen Evolution Reaction in Alkaline Electrolytes , 2012 .

[3]  XAFS investigation of the structure and valency of nickel in some oxycompounds , 1995 .

[4]  A. Szytuła,et al.  Neutron Diffraction Studies of ß-FeOOH , 1970 .

[5]  J. Herrero‐Martín,et al.  Charge disproportionation in La 1 − x Sr x Fe O 3 probed by diffraction and spectroscopic experiments , 2008 .

[6]  M. Balasubramanian,et al.  X-ray Absorption Spectroscopy Studies of the Local Atomic and Electronic Structure of Iron Incorporated into Electrodeposited Hydrous Nickel Oxide Films† , 2000 .

[7]  R. Ma,et al.  Highly Swollen Layered Nickel Oxide with a Trilayer Hydrate Structure , 2008 .

[8]  H. Bode,et al.  Zur kenntnis der nickelhydroxidelektrode—IV. Kristallstrukturuntersuchung des hochoxidierten γ1-Nickelhydroxids , 1971 .

[9]  Bert M. Weckhuysen,et al.  Kβ-detected XANES of framework-substituted FeZSM-5 zeolites , 2004 .

[10]  John Kitchin,et al.  Universality in Oxygen Evolution Electrocatalysis on Oxide Surfaces , 2011 .

[11]  Samuel M. Webb,et al.  SIXpack: a graphical user interface for XAS analysis using IFEFFIT , 2020, International Tables for Crystallography.

[12]  M Newville,et al.  ATHENA, ARTEMIS, HEPHAESTUS: data analysis for X-ray absorption spectroscopy using IFEFFIT. , 2005, Journal of synchrotron radiation.

[13]  O. L. Bacq,et al.  Impact on electronic correlations on the structural stability, magnetism, and voltage of LiCoPO4 battery , 2004 .

[14]  V. Anisimov,et al.  Band theory and Mott insulators: Hubbard U instead of Stoner I. , 1991, Physical review. B, Condensed matter.

[15]  J. Nørskov,et al.  Improved adsorption energetics within density-functional theory using revised Perdew-Burke-Ernzerhof functionals , 1999 .

[16]  Herman Winick,et al.  X-Ray Resonant Raman Scattering: Observation of Characteristic Radiation Narrower than the Lifetime Width , 1976 .

[17]  Yushan Yan,et al.  Efficient water oxidation using nanostructured α-nickel-hydroxide as an electrocatalyst. , 2014, Journal of the American Chemical Society.

[18]  Vittal K. Yachandra,et al.  Structure-activity correlations in a nickel-borate oxygen evolution catalyst. , 2012, Journal of the American Chemical Society.

[19]  Annabella Selloni,et al.  Mechanism and Activity of Water Oxidation on Selected Surfaces of Pure and Fe-Doped NiOx , 2014 .

[20]  G. Młynarek,et al.  The effect of ferric ions on the behaviour of a nickelous hydroxide electrode , 1984 .

[21]  D. Siddons,et al.  Elimination of the inner-shell lifetime broadening in x-ray-absorption spectroscopy. , 1991, Physical review letters.

[22]  M Newville,et al.  IFEFFIT: interactive XAFS analysis and FEFF fitting. , 2001, Journal of synchrotron radiation.

[23]  Marc T. M. Koper,et al.  Thermodynamic theory of multi-electron transfer reactions: Implications for electrocatalysis , 2011 .

[24]  S. Boettcher,et al.  Nickel-iron oxyhydroxide oxygen-evolution electrocatalysts: the role of intentional and incidental iron incorporation. , 2014, Journal of the American Chemical Society.

[25]  Daniel G. Nocera,et al.  In Situ Formation of an Oxygen-Evolving Catalyst in Neutral Water Containing Phosphate and Co2+ , 2008, Science.

[26]  S. Trasatti.  Electrocatalysis in the anodic evolution of oxygen and chlorine , 1984 .

[27]  Maria Chan,et al.  Trends in activity for the water electrolyser reactions on 3d M(Ni,Co,Fe,Mn) hydr(oxy)oxide catalysts. , 2012, Nature materials.

[28]  C. Berlinguette,et al.  Water oxidation catalysis: electrocatalytic response to metal stoichiometry in amorphous metal oxide films containing iron, cobalt, and nickel. , 2013, Journal of the American Chemical Society.

[29]  D. Corrigan.  The Catalysis of the Oxygen Evolution Reaction by Iron Impurities in Thin Film Nickel Oxide Electrodes , 1987 .

[30]  Stefano de Gironcoli,et al.  QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials , 2009, Journal of physics. Condensed matter : an Institute of Physics journal.

[31]  Alexis T. Bell,et al.  An investigation of thin-film Ni-Fe oxide catalysts for the electrochemical evolution of oxygen. , 2013, Journal of the American Chemical Society.

[32]  J. Goodenough,et al.  A Perovskite Oxide Optimized for Oxygen Evolution Catalysis from Molecular Orbital Principles , 2011, Science.

[33]  Venkatasubramanian Viswanathan,et al.  Importance of Correlation in Determining Electrocatalytic Oxygen Evolution Activity on Cobalt Oxides , 2012 .

[34]  C. Humphreys,et al.  Electron-energy-loss spectra and the structural stability of nickel oxide: An LSDA+U study , 1998 .

[35]  S. Boettcher,et al.  Solution-cast metal oxide thin film electrocatalysts for oxygen evolution. , 2012, Journal of the American Chemical Society.

[36]  Stefano de Gironcoli,et al.  Hubbard‐corrected DFT energy functionals: The LDA+U description of correlated systems , 2013, 1309.3355.

[37]  D. Sokaras,et al.  On the chemical state of Co oxide electrocatalysts during alkaline water splitting. , 2013, Physical chemistry chemical physics : PCCP.

[38]  Turner,et al.  A monolithic photovoltaic-photoelectrochemical device for hydrogen production via water splitting , 1998, Science.

[39]  A. Grimaud,et al.  Structural Changes of Cobalt-Based Perovskites upon Water Oxidation Investigated by EXAFS , 2013 .

[40]  Tom Regier,et al.  An advanced Ni-Fe layered double hydroxide electrocatalyst for water oxidation. , 2013, Journal of the American Chemical Society.

[41]  Nathan S. Lewis,et al.  An experimental and modeling/simulation-based evaluation of the efficiency and operational performance characteristics of an integrated, membrane-free, neutral pH solar-driven water-splitting system , 2014 .

[42]  Xiao‐Qing Yang,et al.  The Fe K-edge X-ray absorption characteristics of La1−xSrxFeO3−δ prepared by solid state reaction , 2009 .

[43]  A. Lichtenstein,et al.  First-principles calculations of electronic structure and spectra of strongly correlated systems: the LDA+U method , 1997 .

[44]  S. J. Cyvin,et al.  Hydrogen Bonds of gamma-FeOOH. , 1978 .

[45]  U. Bergmann,et al.  X-ray absorption investigation of the valence state and electronic structure of La1−xCaxCoO3−δ in comparison with La1−xSrxCoO3−δ and La1−xSrxFeO3−δ , 2011 .

[46]  Nathan S. Lewis,et al.  An analysis of the optimal band gaps of light absorbers in integrated tandem photoelectrochemical water-splitting systems , 2013 .

[47]  James R. McKone,et al.  Solar water splitting cells. , 2010, Chemical reviews.

[48]  R. Carr,et al.  In situ x-ray absorption fine structure studies of foreign metal ions in nickel hydrous oxide electrodes in alkaline electrolytes , 1994 .

[49]  Jens K Nørskov,et al.  Theoretical investigation of the activity of cobalt oxides for the electrochemical oxidation of water. , 2013, Journal of the American Chemical Society.

[50]  K. Hodgson,et al.  A Multiplet Analysis of Fe K-Edge 1s → 3d Pre-Edge Features of Iron Complexes , 1997 .

[51]  F. Walsh,et al.  Nickel based electrocatalysts for oxygen evolution in high current density, alkaline water electrolysers. , 2011, Physical chemistry chemical physics : PCCP.

[52]  D. Vanderbilt,et al.  Soft self-consistent pseudopotentials in a generalized eigenvalue formalism. , 1990, Physical review. B, Condensed matter.

[53]  I. Bae,et al.  In situ X-ray absorption fine structure and optical reflectance studies of electrodeposited nickel hydrous oxide films in alkaline electrolytes , 1997 .

[54]  Gerbrand Ceder,et al.  Oxidation energies of transition metal oxides within the GGA+U framework , 2006 .

[55]  A. Oleś,et al.  Neutron Diffraction Study of γ‐FeOOH , 1970 .

[56]  Zhipan Zhang,et al.  Photochemical Route for Accessing Amorphous Metal Oxide Materials for Water Oxidation Catalysis , 2013, Science.

[57]  C. Delmas,et al.  In Situ 57Fe Mössbauer Spectroscopy Study of the Electrochemical Behavior of an Iron‐Substituted Nickel Hydroxide Electrode , 1996 .

[58]  E. Carter,et al.  Water oxidation on pure and doped hematite (0001) surfaces: prediction of Co and Ni as effective dopants for electrocatalysis. , 2012, Journal of the American Chemical Society.

[59]  S. Boettcher,et al.  An Optocatalytic Model for Semiconductor-Catalyst Water-Splitting Photoelectrodes Based on In Situ Optical Measurements on Operational Catalysts. , 2013, The journal of physical chemistry letters.

[60]  R. S. Conell,et al.  In situ Moessbauer study of redox processes in a composite hydroxide of iron and nickel , 1987 .

[61]  Earl W. Cornell,et al.  Combined Catalysis and Optical Screening for High Throughput Discovery of Solar Fuels Catalysts , 2013 .

[62]  R. Rocheleau,et al.  Electrochemical Behavior of Reactively Sputtered Iron‐Doped Nickel Oxide , 1997 .

[63]  A. Yamada,et al.  The nature of lithium battery materials under oxygen evolution reaction conditions. , 2012, Journal of the American Chemical Society.

[64]  Stefano de Gironcoli,et al.  Linear response approach to the calculation of the effective interaction parameters in the LDA + U method , 2004, cond-mat/0405160.

[65]  R. S. Conell,et al.  In situ extended x‐ray absorption fine structure spectroscopy of thin‐film nickel hydroxide electrodes , 1991 .

[66]  Allen L. Johnson,et al.  Near-edge X-ray-absorption fine-structure studies of chemisorbed hydrocarbons: bond lengths with a ruler , 1984 .

[67]  Ankudinov,et al.  Multiple-scattering calculations of x-ray-absorption spectra. , 1995, Physical review. B, Condensed matter.

[68]  H. Jónsson,et al.  Origin of the Overpotential for Oxygen Reduction at a Fuel-Cell Cathode , 2004 .

[69]  Charles C. L. McCrory,et al.  Benchmarking heterogeneous electrocatalysts for the oxygen evolution reaction. , 2013, Journal of the American Chemical Society.