2D Fe-containing cobalt phosphide/cobalt oxide lateral heterostructure with enhanced activity for oxygen evolution reaction

Abstract

Two-dimensional (2D) heterostructures have emerged as promising electrocatalysts towards oxygen evolution reaction due to their unique structural and chemical properties. Moreover, 2D lateral heterostructure with the coupled interface in-plane rather than the vertical direction enables to expose more active sites to catalyst surface, and thus facilitates the OER catalytic activity. Here, 2D FeCo layered double hydroxide/cobalt oxide (FeCo LDH/CoO) nanosheets are synthesized via an instantaneous method utilizing molten alkali as both solvent and reactant. Upon a selective low-temperature phosphorization, 2D Fe-containing cobalt phosphide/cobalt oxide (Fe-CoP/CoO) lateral heterostructure with the optimized electronic structure and activated electronic coupling interface is obtained and exhibits superior catalytic activity (η = 219 mV at 10 mA cm⁻²) compared to most of the reported electrocatalysts towards OER in alkaline electrolyte. Besides, both of the experimental characterization and DFT calculation are performed to illustrate the detailed mechanism of the attractive OER activity. It is uncovered that the coupled interface between CoP and CoO induces the redistribution of electrons, facilitates the adsorption of OH^- anions easily, and thus optimizes Gibbs free energies for water oxidation.