S-scheme heterojunction engineering of CdS/Bi${}_2$WO${}_6$ in breakthrough piezocatalytic nitrogen reduction and hydrogen evolution. Performance, mechanism, and DFT calculations

Herein, a novel bismuth tungstate and cadmium sulfide (CdS/Bi${}_2$WO${}_6$step-scheme (S-scheme) heterojunction piezocatalyst for the first time is developed. The exceptional piezocatalytic nitrogen reduction reaction activity (1.37 mmol L${}^{-1}$ g${}^{-1}$ h${}^{-1}$) is delivered, which is significantly higher compared to pure CdS (0.06 mmol L${}^{-1}$ g${}^{-1}$ h${}^{-1}$) and bare Bi${}_2$WO${}_6$ (0.45 mmol L${}^{-1}$ g${}^{-1}$ h${}^{-1}$), showing an almost 23-fold and 3-fold increase, respectively. This performance greatly exceeds previously reported piezocatalysts and piezo-photocatalysts. Meanwhile, this catalyst also holds outstanding piezocatalytic hydrogen evolution reaction rate of 1.02 mmol g${}^{-1}$ h${}^{-1}$. Relevant experimental and density functional theory (DFT) calculations results demonstrate that the excellent catalytic capacity of CdS/Bi${}_2$WO${}_6$ is mainly ascribed to the construction of S-scheme heterojunction, which greatly promotes piezoelectric performance, enhances the segregating efficiency of charge carriers and redox capacity, regulates electronic structure, optimizes the reaction dynamics processes and reduces the reactions barrier, and induces more active sites. Furthermore, a new piezocatalytic mechanism for the CdS/Bi${}_2$WO${}_6$ S-scheme heterojunction is proposed. This research extends the applications of S-scheme heterojunctions in sustainable energy piezocatalysis and offers insights for designing efficient piezocatalytic systems. (© 2024 Wiley‐VCH GmbH)