CuS Nanosheets Decorated with CoS2 Nanoparticles as an Efficient Electrocatalyst for Enhanced Hydrogen Evolution at All pH Values

The design and fabrication of eco-friendly, highly efficient, and non-noble-metal-based catalysts are demanding challenges in energy-conversion technologies. Herein, we successfully synthesized CuS nanosheets decorated with CoS2, nanoparticles through a facile route. The optimized 3% CoS2-7% CuS catalysts exhibited remarkable electro-catalytic performance, with excellent cyclic stability at all pH values for the hydrogen evolution reaction (HER). They exhibited lower Tafel slopes (46, 52, and 59 mV dec(-1)) and smaller overpotentials (62, 85, and 106 mV) at 10 mA cm(-2) in 0.5 M H2SO4, 1 M KOH, and 0.5 phosphate buffer aqueous solutions, respectively, than other CoS2/CuS, pure CoS2, and pure CuS catalysts. We attribute their high electrocatalytic performance to their unique heterostructure and the synergistic effects between the constituent metal sulfides that provides a large interfacial contact area, numerous charge-transfer pathways, as well as abundant surface reaction active sites, enhancing the charge-carrier transfer during the HER activity.