Interface charge regulation and enhanced photocatalytic hydrogen evolution performance of 3D/2D Co0.2Cd0.8S/Ti3C2 MXene Schottky junctions

The fabrication of electron-coupled heterojunctions with efficient interfacial charge transfer characteristics is one of the key strategies for improving the efficiency of photocatalytic hydrogen evolution. In this study, using bulk Ti3AlC2 MAX as a precursor, two-dimensional layered Ti3C2 MXene (TC) was derived via an etching and exfoliation process. This was then combined with Co0.2Cd0.8S (CCS) nanoparticles to successfully prepare a 3D/2D structured CCS nanoparticle/layered TC (CCST) Schottky junction photocatalyst. Two-dimensional layered TC not only exhibits superior electron transport capabilities, effectively suppressing the recombination of photo-generated carriers, but its unique accordion-like multilayer structure also provides abundant surface-active sites, significantly enhancing the kinetics of the catalytic reaction. Combined with characterization techniques including in-situ X-ray photoelectron spectroscopy (XPS), X-ray photoelectron spectroscopy (in-situ XPS) and Kelvin probe force microscopy (KPFM), as well as density functional theory (DFT) calculations, the precise charge regulation mechanism at the CCST heterojunction interface was systematically confirmed. The photocatalytic hydrogen evolution performance test shows that when the TC addition amount is 15% (CCST-15), the sample exhibits the best catalytic activity, with a photocatalytic hydrogen evolution amount of up to 233.92 μmol within 5 h, which is approximately 4.11 times higher than that of the pure CCS sample. This study provides a theoretical basis for the preparation of novel and high-efficiency Schottky junction photocatalysts and the efficient conversion of solar energy to hydrogen.