Tailoring the d-Band Centers Endows (Ni_<i>x</i>Fe_1–<i>x</i>)₂P Nanosheets with Efficient Oxygen Evolution Catalysis

Abstract

The rational design of oxygen evolution reaction (OER) catalysts from the perspective of electronic structure is highly desirable to optimize electrocatalytic activity. Monometallic phosphides such as Ni2P have been shown to be active toward OER, but their performance remains unsatisfactory. Herein, guided by the theoretical mechanism study of the intrinsic high electroactivity revealed in the d-band center (Ed) theory, the Fe-substituted Ni2P ((NixFe1–x)2P) nanosheets grown directly on NiFe foam are designed and synthesized. As OER electrocatalysts in alkaline media, the (NixFe1–x)2P nanosheets show an overpotential of 166 mV to deliver the current density of 10 mA cm–2, which is superior to the Ni2P and most reported transition-metal-based catalysts. Combining DFT simulations with experiments reveals that the enhanced activity results from the moderate rise in Ed energy levels, which balances the adsorption and desorption capacities of the oxygen-containing intermediates (*O, *OH, and *OOH). This work supplies valuable insights for the rational design and construction of efficient doped electrocatalysts under the guidance of the d-band center theory.