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

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-CoO_X/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-CoO_X/NiFe LDHs heterointerfaces are easily transferred from Ni²⁺ to Co³⁺ because that the amorphous configuration of P-CoO_X can well induce Ni-O-Co orbital coupling. The electron transfer of Ni²⁺ to the surrounding Fe³⁺ and Co³⁺ will lead to the unoccupied e_g orbitals of Ni³⁺ that can promote water dissociation and accelerate ^*OOH migration to improve OER catalytic performance. The optimized P-CoO_X/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.