Hierarchical CuCo2S4 Nanoflake Arrays Grown on Carbon Cloth: A Remarkable Bifunctional Electrocatalyst for Overall Water Splitting

Abstract Fabricating self‐supporting electrocatalysts with double functions for overall water splitting is a promising strategy for clean energy generation. Herein, spinel‐based CuCo 2 S 4 nanoflakes were grown vertically on carbon cloth (CC) substrate to obtain hierarchical self‐supporting CuCo 2 S 4 /CC electrocatalysts through a hydrothermal process. The influence of hydrothermal time on the surface morphology and electrocatalytic properties of the CuCo 2 S 4 /CC was investigated. The rational synthetic approach can significantly reduce the diffusion path and promote the transfer of charge. As a result, the optimized CuCo 2 S 4 /CC exhibits a significantly higher electrocatalytic activity than the control single metal sulfide catalysts (CoS 1.097 /CC and CuS/CC) in 1.0 M KOH solution, and relatively overpotentials of 204 and 280 mV are demanded to generate a current density of 10 mA cm −2 for hydrogen evolution reaction and oxygen evolution reaction, respectively. The significantly enhanced electrocatalytic activity benefits from the synergetic effect of the fast charge transport and abundant catalytic active sites. Moreover, in an overall water splitting system, a two‐electrode setup constructed using CuCo 2 S 4 /CC as both cathode and anode shows a low voltage of 1.58 V at 10 mA cm −2 and high durability. This study provides a rational strategy for improving the overall water splitting performance by constructing self‐supporting spinel‐based catalysts.