0D/2D NiS2/V-MXene composite for electrocatalytic H2 evolution

As a member of the family of so-called MXenes, two-dimensional vanadium carbide (V2CTx, denoted as V-MXene) used in electrocatalytic hydrogen evolution reaction (HER) is still in the stage of theoretical study without significant experimental exploration. Here, we present the theoretical and experimental studies on the intrinsic structural and electrochemical properties of V-MXene-based hybrid (NiS2/V-MXene) to verify the possibility of using it as a potential electrocatalyst for HER. For the purpose of comparison, the most popular titanium carbide (Ti3C2Tx, denoted as Ti-MXene) is studied too. As a proof of concept, NiS2/V-MXene and NiS2/Ti-MXene, are designed, prepared and experimentally explored. As expected, NiS2/V-MXene is proved to be a better electrocatalyst for HER than NiS2/Ti-MXene due to its faster electronic transfer and favorable interactions. The tight cover of NiS2 nanoparticles not only prevents V-MXene from restacking but also favors the exposure of extra active sites to accelerate the electrolysis process. Such a unique sandwich-like architecture is highly preferable to provide larger contact interface and more pathways for electron migration and mass diffusion during the electrolysis. Meanwhile, the predicted electron transfer from V-MXene to NiS2 is confirmed experimentally using X-ray photoelectron spectroscopy. This research may provide a guide for the design and development of V-MXene-based electrocatalysts for HER, and expand their potential applications.