Constructing a Hetero-interface Composed of Oxygen\nVacancy-Enriched Co₃O₄ and Crystalline–Amorphous\nNiFe-LDH for Oxygen Evolution Reaction

Abstract

The\ndevelopment of high-performance electrocatalysts is a highly\nefficient strategy to optimize the sluggish kinetic property of the\noxygen evolution reaction (OER). Herein, we synthesize a kind of nickel\nfoam (NF)-supported electrocatalyst composed of a one-dimensional\nCo₃O₄ nanowire as the core and a two-dimensional\nNiFe-LDH nanosheet as the shell (denoted as NiFe-60/Co₃O₄@NF). Fluorine is introduced into the precursor Co­(OH)­F\nof Co₃O₄, which results in improved thermal\nstability and significantly increased regularly distributed oxygen\nvacancies, while the electrochemically deposited NiFe-LDH nanosheets\npossess a crystalline/amorphous hybrid structure. As a result, the\nhetero-interface mainly constituting Ni species from NiFe-LDH and\nCo₃O₄ from Co­(OH)F contributes to the interaction\nbetween Co and Fe species and facilitates the electron transfer. Simultaneously,\nthe interaction between oxygen vacancies in Co₃O₄ and coordinatively unsaturated Fe species in the amorphous area\nin NiFe-LDH is also determined, finally completing the electron backtracking.\nBenefiting from these factors, only low overpotentials of 221 and\n257 mV are required to deliver the current densities of 100 and 500\nmA cm^–2, respectively, with a quite small Tafel\nslope of 34.6 mV dec^–1 during OER for the well-designed\nNiFe-60/Co₃O₄@NF electrocatalyst.