Double S-scheme Cu2−xSe/twinned-Cd0.5Zn0.5S homo-heterojunctions with surface plasmon effects for efficient photocatalytic H2 evolution.

The double S-scheme electron transfer pathway of the Cu 2−x Se/T-Cd 0.5 Zn 0.5 S system leverages the synergistic effect of interface and bulk phase S-scheme homo-heterojunctions, along with the utilization of "hot electrons" generated by the LSPR effect, to facilitate efficient charge separation and transfer, thereby achieving enhanced performance in H 2 evolution. [Display omitted] • The twinned-Cd 0.5 Zn 0.5 S, composed of zinc blende and wurtzite Cd 0.5 Zn 0.5 S have excellent H 2 evolution activity. • Cu 2−x Se can further promote charge separation and enhance the H 2 evolution kinetics. • The Cu 2−x Se/T-Cd 0.5 Zn 0.5 S homo-heterojunctions with interface and bulk synergistic double S-scheme. • The injection of "hot electrons" generated by the LSPR effect of Cu 2−x Se into the T-Cd 0.5 Zn 0.5 S. The enhancement of charge separation and utilization efficiency in both the bulk phase and interface of semiconductor photocatalysts, as well as the expansion of light absorption range, are crucial research topics in the field of photocatalysis. To address this issue, twinned Cd 0.5 Zn 0. 5S (T -CZS) homojunctions consisting of wurtzite Cd 0.5 Zn 0.5 S (WZ-CZS) and zinc blende Cd 0.5 Zn 0.5 S (ZB-CZS) were synthesized via a hydrothermal method to facilitate the bulk-phase charge separation. Meanwhile, Cu 2−x Se with localized surface plasmon resonance effect (LSPR) generated by Cu vacancies was also obtained through a hydrothermal process. Due to their opposite electronegativity, a solvent evaporation strategy was employed to combine Cu 2−x Se and T -CZS by intermolecular electrostatic. After optimization, the photocatalytic hydrogen (H 2) evolution rate of 5 wt% Cu 2−x Se/ T -CZS reached an impressive value of 60 mmol∙h−1∙g−1, which was 4.6 and 66.6 times higher than that of pure Cu 2−x Se and T -CZS, respectively. Furthermore, this composites demonstrated a remarkable rate of 0.46 mmol∙h−1∙g−1 under near-infrared (NIR) wavelength (>800 nm). The enhanced performance observed in Cu 2−x Se/ T -CZS can be attributed to its unique and efficient double S-scheme charge transfer mechanism which effectively suppresses rapid recombination of electron-hole pairs both within the bulk phase and at the surface interfaces; this conclusion is supported by Density Functional Theory (DFT) calculations as well as electron paramagnetic resonance spectroscopy analysis. Moreover, incorporation of Cu 2−x Se enables effective utilization ultraviolet visible-near infrared (UV–Vis-NIR) light by the composites while facilitating injection "hot electrons" into T -CZS for promoting photocatalytic reactions. This study provides a potential strategy for achieving efficient solar energy conversion through synergistic integration of non-stoichiometric plasmonic materials with photocatalysts with twinned-twinned structures. [ABSTRACT FROM AUTHOR]