Activity and stability of CoMxOy/Co3O4 (M = Mo, W, V) nano-arrays synthesized by self-templated method for water oxidization

Developing highly active and steady electrocatalysts for oxygen evolution reaction (OER) is crucial to achieve efficient electrochemical water splitting. Herein, we report a facile in situ self-assembly strategy for the synthesis of catalysts (CoMoO4/Co3O4/NF, CoWO4/Co3O4/NF and Co3V2O8/Co3O4/NF) with hierarchical 1D nanostructure. This 1D well-aligned structure and phase interpenetration of mixed Co species provide a rapid channel for charge transfer and mass exchange. Meanwhile, the internal Co3O4 nanowires serve as a framework to host abundant CoMxOy (M = Mo, W, V) materials and this structure is beneficial to the exposure of OER active phases. As a result, these electrocatalysts exhibit excellent OER activities with low overpotentials. Besides, after 1000 voltammetry cycles, only slight increase in the overpotential verifies the excellent stability of these catalysts during the alkaline oxygen evolution reaction process. Based on postmortem characterizations, a dissolution–redeposition process is proposed to explain the formation of Co(oxy)hydroxides on the surface of the catalysts.