Reprogramming thermodynamic-limiting oxidation cycle in NiFe-based oxygen evolution electrocatalyst through Mo doping induced surface reconstruction

Abstract

Engineering of robust nonprecious electrocatalysts toward anodic oxygen evolution reaction (OER) is of great significance for lowering the cost and energy consumption for renewable fuel production. Herein, we report NiFeMoOx nanosheets as high-performance OER electrocatalyst through promoting the thermodynamic-limiting oxidation cycle process in NiFe oxyhydroxide via high-valence Mo doping. The NiFeMoOx nanosheets are prepared by an elaborate in-situ solvothermal etching-depositing process with NiFe alloy framework as substrate and metal precursors. The resultant nanosheets exhibit outstanding alkaline OER activity, requires only 235/282/327 mV overpotentials to achieve current density of 10/100/300 mA cm−2, respectively, with a good long-term stability at 20 mA cm−2 for 72 h. Besides, the Tafel slope low to 28.1 mV dec−1 indicates a favorable OER kinetics. The superior catalytic activity of NiFeMoOx nanosheets should be attributed to the lower oxidation states of Ni and Fe induced by high-valence dopant, leading to easier surface reconstruction at low charge oxidation cycling during OER, thereby effectively reducing the overpotential. The synergy between the electronic effect among multimetallic sites and the unique morphology is expected to inspire the development of robust OER electrocatalyst for industrial application.