Interfacial Engineering of Heterostructured Co(OH)2/NiPx Nanosheets for Enhanced Oxygen Evolution Reaction

Abstract The oxygen evolution reaction (OER) remains a bottleneck for the overall water splitting. Electrocatalysts with superior activity and stability are still highly desired. Herein, a stepwise electrochemical strategy is developed to prepare Co(OH) 2 /NiP x nanosheet arrays with intimate and abundant heterostructures. The Co(OH) 2 nanosheets, which are first electrodeposited on a blank carbon cloth electrode, serve as the substrate for the nucleation and growth of NiP x . The resultant heterointerfaces are well regulated by altering the loading of NiP x . The heterostructured Co(OH) 2 /NiP x with optimal NiP x loading demonstrate significantly enhanced conductivity and hydrophilicity, which greatly facilitate electron and mass transfer. In addition, strong electronic interaction between Co(OH) 2 and NiP x is observed, favoring the generation of high‐valence cobalt center, thus the electrocatalytic performances toward OER are remarkably improved. The heterostructured Co(OH) 2 /NiP x nanosheets achieve the current density of 10 mA cm −2 at an overpotential of 236 mV, while the corresponding values for Co(OH) 2 and the benchmark Ir/C are 292 and 262 mV, respectively. This study provides a facile and effective strategy to fabricate transition metal hydroxide/phosphide composite nanomaterials with intimate heterostructures, enhanced conductivity, and improved wettability, which opens a new direction for the design of highly active electrocatalysts.