Stannum vacancies at precise interface of 2D/2D g-C3N4/SnS S-scheme heterojunction boost up photocatalysis

Abstract

Advanced semiconductor photocatalysts have significant potential for efficient alcohol photooxidation. In this study, a novel 2D/2D g-C₃N₄/SnS (CNS) S-scheme heterojunction was fabricated via a one-step hydrothermal stripping and assembly method, in which SnS nanosheets were in situ anchored on exfoliated g-C₃N₄ nanosheets. The as-prepared CNS composites exhibit superior photocatalytic performance in the photooxidation of benzyl alcohol (BA) to benzaldehyde. This is because constructing the 2D/2D heterojunction interface efficiently provided numerous surface Sn vacancies, enhancing light absorption, and encouraging charge separation and transfer. CNS-10 achieved the best photocatalytic activity with a promising formation rate of 1.63 mmol_{reacted BA} g_catal.⁻¹ h⁻¹, which is 4-fold more significant than that of pristine g-C₃N₄. Femtosecond time-resolved transient absorption spectroscopy (fs-TAS) reveals that the exceptional performance could be attributed to the effective synergistic promotion of shallow electron trapping in g-C₃N₄ and inhibition of the recombination of photogenerated electrons and holes. Furthermore, the main active species and possible reaction mechanisms during the photocatalytic process were also examined. Overall, this study can offer insights into the rational construction of 2D/2D S-scheme photocatalysts.