Facile Construction of Three-Dimensional Heterostructured CuCo2S4 Bifunctional Catalyst for Alkaline Water Electrolysis

Developing an efficient multi-functional electrocatalyst with high efficiency and low cost to replace noble metals is significantly crucial for the industrial water electrolysis process and for producing sustainable green hydrogen (H-2) fuel. Herein, ultrathin CuCo2S4 nanosheets assembled into highly open three-dimensional (3D) nanospheres of CuCo2S4 (Cu/Co = 33:67) were prepared by a facile one-pot solvothermal approach and utilized as a bifunctional electrocatalyst for efficient overall water splitting. The as-prepared CuCo2S4 is characterized structurally and morphologically; the BET surface area of the CuCo2S4 (Cu/Co = 33:67) catalyst was found to have a larger specific surface area (21.783 m(2)g(-1)) than that of other catalysts with a Cu/Co ratio of 67:33, 50:50, and 20:80. Benefiting from a highly open structure and ultrathin nanosheets with excellent exposure to catalytically active sites, CuCo2S4 (Cu/Co = 33:67) is identified as an efficient catalyst for the proton reduction and oxygen evolution reactions in 1 M KOH with an overpotential of 182 and 274 mV at 10 mA cm(-2), respectively. As expected, a low cell voltage of 1.68 V delivers a current density of 10 mA cm(-2). Stability and durability are also greatly enhanced under harsh alkaline conditions. Therefore, this work provides a simple strategy for the rational design of spinel-based transition metal sulfide catalysts for electrocatalysis.

Automated summary

Developing an efficient and low-cost multi-functional electrocatalyst to replace noble metals is crucial for industrial water electrolysis and sustainable green hydrogen fuel production. In this study, ultrathin CuCo2S4 nanosheets assembled into highly open three-dimensional nanospheres were prepared and used as a bifunctional electrocatalyst for overall water splitting. The CuCo2S4 catalyst exhibited a larger specific surface area and showed excellent activity and stability for proton reduction and oxygen evolution reactions in alkaline conditions. This work provides a simple strategy for the design of spinel-based transition metal sulfide catalysts for electrocatalysis.