Amorphous P-CoOX Promotes the Formation of Hypervalent Ni Species in NiFe LDHs by Amorphous/Crystalline Interfaces for Excellent Catalytic Performance of Oxygen Evolution Reaction.

ABSTRACT

Water electrolysis has become an attractive hydrogen production method. Oxygen evolution reaction (OER) is a bottleneck of water splitting as its four-electron transfer procedure presents sluggish reaction kinetics. Designing composite catalysts with high performance for efficient OER still remains a huge challenge. Here, the P-doped cobalt oxide/NiFe layered double hydroxides (P-CoOX/NiFe LDHs) composite catalysts with amorphous/crystalline interfaces are successfully prepared for OER by hydrothermal-electrodeposition combined method. The results of electrochemical characterizations, operando Raman spectra, and DFT theoretical calculations have demonstrated the electrons in the P-CoOX/NiFe LDHs heterointerfaces are easily transferred from Ni2+ to Co3+ because that the amorphous configuration of P-CoOX can well induce Ni-O-Co orbital coupling. The electron transfer of Ni2+ to the surrounding Fe3+ and Co3+ will lead to the unoccupied eg orbitals of Ni3+ that can promote water dissociation and accelerate *OOH migration to improve OER catalytic performance. The optimized P-CoOX/NiFe LDHs exhibit superior catalytic performance for OER with a very low overpotential of 265 mV at 300 mA cm-2 and excellent long-term stability of 500 h with almost no attenuation at 100 mA cm-2. This work will provide a new method to design high-performance NiFe LDHs-based catalysts for OER.