Promoting photocatalytic hydrogen evolution by introducing hot islands: SnSe nanoparticles on ZnIn2S4 monolayer

Abstract The contribution of the photothermal effect has been found to enhance solar water splitting. However, the in-depth experimental exploration of the physical and chemical mechanisms is challenging. Herein, an ideal model of photothermal material SnSe nanoparticles acting as “hot islands” on ZnIn2S4 monolayer was considered as an example for investigation. Compared to pristine ZnIn2S4, SnSe/ZnIn2S4 exhibited further improved photocatalytic activity upon the addition of near-infrared (NIR) light under visible irradiation due to the photothermal contribution; indicating that the photothermal effect plays an auxiliary role in the enhancement of the photocatalytic performance. Furthermore, “hot islands” can induce an increase in temperature to accelerate the photocatalytic reaction, and the photothermal contribution is as high as 11.8% by NIR illumination. More importantly, a series of experiments were designed under additional light conditions to investigate the photocatalytic mechanism of the photothermal influence, which included the charge density, the carrier transport and the charge carrier mobility. This study provides insight into the mechanism with favourable experimental evidence and lays a foundation for further investigation of the role of the photothermal effect in photocatalysis.