2D/1D CaIn2S4/TiO2 S-scheme heterojunction: In-situ hydrothermal synthesis and enhanced photocatalytic H2 evolution

Constructing S-scheme heterojunction between TiO 2 and other reduction semiconductors can effectively enhance the intrinsically low carrier separation efficiency and increase the reduction ability of single TiO 2 photocatalyst. In this work, a hydrothermally synthesized 2D CaIn 2 S 4 nanosheets, possessing the merits of narrow bandgap and strong reduction ability, have been developed to construct S-scheme heterojunction with TiO 2 nanofiber. It is found that the 2D CaIn 2 S 4 nanosheets can be in-situ assembled onto the surface of 1D TiO 2 nanofiber to form a 2D/1D CaIn 2 S 4 /TiO 2 S-scheme heterojunction, which then presents an extremely reinforced H 2 -evolution rate (ca. 564.66 μmol·g –1 ·h –1 ), about 3- and 7-fold higher than that of the single TiO 2 and CaIn 2 S 4 , respectively. Finally, the in-situ XPS, DFT calculations, steady and transient-state spectrum results indicate that the formation of S-scheme heterojunctions between CaIn 2 S 4 and TiO 2 . This work may deliver a novel and insightful inspiration for the development of high-efficiency S-scheme heterojunction photocatalysts. • CaIn 2 S 4 /TiO 2 nanofiber heterojunction was prepared by a facile hydrothermal route. • In-situ XPS was investigated to elucidate the S-scheme heterojunction mechanism. • The CaIn 2 S 4 /TiO 2 nanofibers exhibited an excellent H 2 -evolution rate of ca. 564.66 μmol·g –1 ·h –1 .