MoS2/Zn3In2S6 composite photocatalysts for enhancement of visible light-driven hydrogen production from formic acid

Enhancing the separation efficiency of photogenerated carriers is propitious for the promotion of photocatalytic hydrogen production from formic acid decomposition. Herein, MoS2/Zn3In2S6 (MoS2/ZIS6) composite photocatalysts containing varying mass percentages of MoS2 were obtained by a straightforward synthetic method. The results confirmed that MoS2, as a cocatalyst, markedly promoted the photogenerated charge separation efficiency and visible light-driven hydrogen production activity of ZIS6 (λ > 400 nm). Specifically, the as-prepared 0.5% MoS2/ZIS6 photocatalyst exhibited the highest photocatalytic hydrogen production rate (74.25 µmol·h−1), which was approximately 4.3 times higher than that of ZIS6 (17.47 µmol·h−1). The excellent performance of the 0.5% MoS2/ZIS6 photocatalyst may be due to the fact that MoS2 has a low Fermi energy level and can thus enrich photogenerated electrons from ZIS6, and furthermore reduce H+ derived from formic acid, to form hydrogen. The structure and morphology of the MoS2/ZIS6 photocatalysts and the reactive species were determined by X-ray diffraction, transmission electron microscopy, and field emission scanning electron microscopy, among others; a plausible mechanistic rationale is discussed based on the results.