Improved All-solid-state Z-scheme Photocatalytic System Based on TiO₂/Ag-Pd/CdZnS

We present an innovative Z-scheme photocatalytic system, TiO2/Ag-Pd/Cd0.8Zn0.2S, exhibiting remarkable stability in aqueous solutions containing benzyl alcohol/acetic acid. Its performance rivals that of the benchmark Z-scheme catalyst, ZnO/Pt/Cd0.8Zn0.2S. Thorough characterizations were performed using XRD, XPS, TEM, and UV-Vis techniques, examining both the entire Z-scheme system and its individual components, namely Ag-Pd/TiO2 and Cd0.8Zn0.2S. The standout performer, TiO2/Ag-Pd/Cd0.8Zn0.2S, demonstrated an apparent quantum yield (AQE) of 7 % within the 350-650 nm range. In contrast, AQEs for Ag-Pd/TiO2 and Cd0.8Zn0.2S were 0.6 % and 2.1 %, respectively, under identical conditions. Furthermore, we propose a charge transfer mechanism supported by femtosecond transient absorption spectroscopy (FTAS). This investigation not only introduces a stable Z-scheme system with superior photocatalytic hydrogen production capabilities but also advances the FTAS technique for mechanistic exploration. In essence, our research paves the way for more efficient metal oxide/metal/Cd(Zn)S hybrid systems in the realm of photocatalysis.