Synergistic effects of sulphur vacancies and MoS2 on the photocatalytic activity of CdxZn1-xS for H2 evolution

Abstract

Efficient photocatalysts nurture great potential for harnessing sunlight to produce chemical energy, a pivotal step towards sustainable fuel production. However, designing such systems poses significant challenges due to the complex interaction between light absorption and charge carrier dynamics. In an attempt to address these challenges, this study introduces a novel approach, combining bulk-twinned homojunction CdxZn1-xS photocatalysts with sulphur vacancies. These CdxZn1-xS photocatalysts are seamlessly integrated with molybdenum disulfide (MoS2) to optimize photocatalytic properties and enhance charge transfer via the formation of heterojunctions. Due to its unique crystal structure, the twinned homojunction in CdxZn1-xS enhances light absorption and charge carrier generation. The integrated sulphur vacancies perform several functions: they expediate light adsorption and inhibit electron-hole recombination. These vacancies were initially introduced into the bulk structure during CdxZn1-xS solid solution synthesis. Further, MoS2 provided an augmentation at the surface modification level, thus enhancing their functional role and amplifying their impact on the overall photocatalytic efficiency. The heterojunction formed between MoS2 and CdxZn1-xS provides an integrated efficient platform for overall performance. The composite nanocrystals, wurtzite/zinc-blende twinned MoS2/CdxZn1-xS, were synthesized via an N, N-dimethylformamide-assisted solvothermal method. Detailed characterization was conducted to establish correlations among activity, morphology, and surface properties. The resulting composite photocatalysts demonstrated improved solar hydrogen generation activity and stability, surpassing the performance of twinned crystal CdxZn1-xS.