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 Ni 2+ to Co 3+ because that the amorphous configuration of P-CoO X can well induce Ni-O-Co orbital coupling. The electron transfer of Ni 2+ to the surrounding Fe 3+ and Co 3+ will lead to the unoccupied e g orbitals of Ni 3+ 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.