Facile preparation of CoNiS/MXene/polypyrrole electrocatalyst with mischcrystal-amorphous interfaces for hydrogen evolution reaction

Electrocatalytic hydrogen evolution reaction (HER) offers a sustainable pathway for clean hydrogen production, while the developing of non-Pt catalysts with high activity and durability remains challenging. This work presents a CoNiS/MXene/polypyrrole (PPy) composite synthesized via a novel 2-step electrodeposition method, enabling precise control over morphology and interfacial properties. The catalyst achieves a low overpotential of 147 mV at 10 mA cm⁻² in alkaline media, rivaling state-of-the-art non-Pt HER catalysts. Remarkably, it retains 99% activity after 2000 CV cycles and 12 h of continuous operation, demonstrating exceptional stability. Where, the mischcrystal-amorphous interfaces of CoNiS provides abundant active sites for HER. And the 3D-continuous structure of MXene/PPy offers a large specific surface area and efficient electron-transfer pathways, promoting high-speed charge transport and mass diffusion. The interfacial coupling between CoNiS and the MXene/PPy matrix was considered facilitating efficient charge transfer across their heterojunction interfaces. This interaction effectively prevents the agglomeration and structural degradation of CoNiS nanosheets during the electrocatalytic process, thereby significantly enhancing the stability of the catalyst. The synergistic effects of CoNiS, PPy, and MXene result in an optimized electronic structure and enhanced catalytic kinetics.