1D/2D TiO2/ZnIn2S4 S-scheme heterojunction photocatalyst for efficient hydrogen evolution

Abstract

TiO2 is a promising photocatalyst with limited use in practical applications owing to its wide bandgap, narrow light response range, and rapid recombination of photoexcited carriers. To address these limitations, a novel 1D/2D TiO2/ZnIn2S4 heterostructure was designed according to the principles of the S-scheme heterojunction. The TiO2/ZnIn2S4 (TZISx) hybrids prepared via a hydrothermal method afforded significant improvement in photocatalytic hydrogen evolution (PHE) in comparison to pristine TiO2 and ZnIn2S4. In particular, the optimal TZIS2 sample (mass ratio of ZnIn2S4 to TiO2 was 0.4) exhibited the highest PHE activity (6.03 mmol/h/g), which was approximately 3.7 and 2.0 times higher than those of pristine TiO2 and ZnIn2S4, respectively. This improvement in the PHE of the TZIS2 sample could be attributed to the formation of an intimate heterojunction interface, high-efficiency separation of charge carriers, abundant reactive sites, and enhanced light absorption capacity. Notably, theoretical and experimental results demonstrated that the S-scheme mechanism of interfacial electron transfer in the TZISx composites facilitated the transfer and separation of photoexcited charge carriers, resulting in more isolated photoexcited electrons for the PHE reaction.