Role of SnS2 in 2D-2D SnS2/TiO2 Nanosheet Heterojunctions for Photocatalytic Hydrogen Evolution

Constructing heterojunctions with face-to-face interface is a new avenue for accelerating the charge separation in semiconductor photocatalysts toward highly efficient solar water splitting systems. Here, a novel SnS2/TiO2 2D-2D ultrathin nanosheet heterostructure was fabricated via a hydrothermal route in two steps. The obtained 2D-2D SnS2/TiO2 nanojunction has not only provided large contact areas but also shortened the charge transport distance, resulting in significantly enhanced photocatalytic H-2 evolution property. The H-2 generation rate obtained for the optimized sample reaches 652.4 mu mol h(-1)g(1), far exceeding (similar to 8 times) that of pristine TiO2 and SnS2 ultrathin nanosheets under simulated solar irradiation. Moreover, further analysis reveals a photoinduced carrier transfer from TiO2 to SnS2 at the interface junction, which causes a partial reduction of the SnS2 cocatalyst to SnS in the nanocomposite during the photocatalytic reactions. These results not only demonstrate that the construction of 2D-2D heterojunction is a promising approach to improve the photocatalytic H-2 production activity of nanostructured semiconductor photocatalysts but also provide new understanding into the role and evolution of SnS2 nanosheets during the photocatalytic reaction process in heterogeneous photocatalyst systems.