Efficient catalysts for oxygen evolution reaction (OER) based on earth abundant elements are necessary for wide spread application of photochemical energy conversion and storage. Recently, mixed Ni-Fe oxides thin films have been shown to achieve very low OER overpotentials (~0.3 V at 10 mA cm-2) with minimum at approximately 50% of Ni-Fe mixing (1). Subsequent X-ray absorption spectroscopy of these films have revealed mixed NixFe1-xOOHy layered type structures in edge-sharing octahedral arrangement. Our ab-initio calculations identify structures (i.e., y stochiometry) consistent with experiments. Next, we are able to explain observed increase of in Ni(II)/Ni(III) redox transition with increasing Fe content. Finally, detailed calculations of OER activity reveal role of Ni-Fe neighbors in the activity enhancement.
(1) Louie, M. W.; Bell, A. T. J. Am. Chem. Soc. 2013, 135, 12329-12337.
SLAC National Accelerator Laboratory, Lawrence Berkeley National Laboratory
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