A novel direct Z-scheme heterojunction of CoTiO3/ZnIn2S4 for enhanced photocatalytic H2 evolution activity.

The shortage of fossil energy has become a growing global concern. It is particularly important to make full use of the infinite solar energy resources, and transform them into sustainable and clean energy. The development of hydrogen energy has become a feasible solution to solve the energy shortage problem. The preparation of photocatalysts featuring efficient charge transfer channels and high hydrogen production activity provides a pathway for the development of hydrogen energy. In this paper, we report for the first time the direct assembly of 2D ZnIn 2 S 4 (ZIS) nanosheets on the surface of CoTiO 3 (CTO). The synthesized CoTiO 3 /ZnIn 2 S 4 (CTO/ZIS) photocatalyst features a direct Z-scheme charge transfer channel, which enhances the separation rate of photogenerated carriers, and accelerates the photocatalytic H 2 evolution (PHE) rate. Without the assistance of any co-catalyst, the PHE rate of prepared CoTiO 3 /ZnIn 2 S 4 was as high as 5.21 mmol g−1 h−1. Moreover, the H 2 evolution rate of CoTiO 3 /ZnIn 2 S 4 almost did not decrease significantly after four consecutive 4 h cycles. This investigation provides a valuable approach for the exploitation of novel and efficient Z-scheme photocatalysts in the application of solar energy to hydrogen energy conversion. Using the Z-scheme CoTiO 3 /ZnIn 2 S 4 photocatalyst, water is decomposed under visible light irradiation to produce large amounts of H 2. The conversion of solar energy to hydrogen energy is realized. [Display omitted] • This is the first report of in situ assembly of ZnIn 2 S 4 nanosheets on CoTiO 3 surface. • The as-prepared CoTiO 3 /ZnIn 2 S 4 showed a new Z-scheme heterojunction. • The CoTiO 3 /ZnIn 2 S 4 heterojunction displayed an improved photocatalytic hydrogen evolution rate. [ABSTRACT FROM AUTHOR]