A crystalline–amorphous Cu-CuS2/NiCoS composite electrocatalyst with a hydrangea-like structure for efficient hydrogen evolution reaction

Abstract

With the goal of accomplishing sustainable development and the "carbon peak and carbon neutral", it remains extremely challenging to fabricate an electrocatalyst for the hydrogen evolution reaction (HER) that is both simple and effective. In this study, a hydrangea-like Ni foam (NF)/Cu-CuS₂/NiCoS composite with a crystalline–amorphous structure was prepared by combining Hs1ydrothermal and electrodeposition. Transition metal sulfides were strategically selected as electrocatalysts in this investigation owing to their remarkable electrical conductivity and exceptional structural stability. The hydrangea-like Cu-CuS₂ provided a large active area for the NiCoS nanospheres, effectively mitigating the agglomeration of the NiCoS catalyst while enabling its homogeneous dispersion throughout the substrate. The NF/Cu-CuS₂/NiCoS composite synergistically integrates the good electrical conductivity and structural stability of crystalline Cu-CuS₂ and the high-density active sites and optimized electronic configuration of amorphous NiCoS, thereby demonstrating exceptional performance for HER. Further, it also exhibited the protective effect of a composite structure and the synergistic effect of the crystalline and amorphous phases. The NF/Cu-CuS₂/NiCoS electrocatalyst (40 mV @ 10 mA·cm⁻²) demonstrated outstanding HER performance in alkaline media.