Few-layer WS2 decorating ZnIn2S4 with markedly promoted charge separation and photocatalytic H2 evolution activity

Abstract

Exploiting the low-cost, abundant and noble-metal-free cocatalysts was still a research hotspot in the photocatalysis field. Herein, few-layer WS2 decorating ZnIn2S4 heterojunctions were successfully fabricated by a two-step procedure including exfoliating bulk WS2 and post-sintering treatment. The multiple characterization techniques were employed to investigate the properties of as-prepared WS2/ZnIn2S4 heterojunctions. The photocatalytic activities were evaluated by H2 evolution performances, and the results revealed that the activities would be significantly promoted by integrating a little amount of WS2 with ZnIn2S4. Moreover, the optimal loading amount of WS2 was about 3 wt% in the heterojunctions, corresponding to the H2 evolution rate of 2.55 mmol g−1h−1 and the apparent quantum efficiency (AQE) of 3.2% at 420 nm monochromatic light. Based on the photoelectrochemical and photoluminescence (PL) spectra tests, the effective charge separation and transfer in the WS2/ZnIn2S4 heterojunction were convincingly corroborated, which was beneficial for the improvement of photocatalytic activity. Furthermore, the few-layer WS2 as cocatalysts could also offer the sufficient active sites to facilitate the H2 evolution. The present work would provide some insights for the development of non-noble-metal cocatalysts in the photocatalysis region.