Boosted electron-transfer by coupling Ag and Z-scheme heterostructures in CdSe-Ag-WO3-Ag for excellent photocatalytic H2 evolution with simultaneous degradation

Abstract

• The Z-scheme CdSe-Ag-WO 3 -Ag is prepared via continuous photo-assisted process. • It realized without Pt efficient H 2 evolution from organic pollutant wastewater. • CdSe-Ag-WO 3 -Ag conforms to Z-scheme e - move mode: CB/WO 3 to Ag and Ag to VB/CdSe. • Boosted electron-transfer by coupling plasmonic Ag and Z-scheme heterostructures. • The mechanism was verified by experiments, in situ XPS and DFT calculations. Coupling the heterojunction system with surface plasmon resonance (SPR) effect is an innovative and feasible strategy to improve photocatalyst. An excellent Z-scheme CdSe-Ag-WO 3 -Ag photocatalyst was constructed via continuous photo-assisted process, which exhibited superior photocatalytic activity in H 2 evolution (448.31 μmol•g −1 for 4 h) with simultaneous degradation of CFZ (96.32% in just 30 min) compared with CdSe-WO 3 , CdSe and WO 3 . This developed system conforms to Z-scheme electron transfer mode: CB/WO 3 to Ag NPs, Ag NPs to VB/CdSe. It was verified by experiments, DFT simulation and in situ XPS characterization. So the strong reducing electron in CB/CdSe and the strong oxidizing hole in VB/WO 3 were retained for H 2 evolution and degradation, respectively. The coupling Ag with Z-scheme heterojunction can realize rapid electron transfer and utilization. Because the Z-scheme heterojunction inhibits recombination of carriers of the single catalyst itself and enhances electrons life, Ag acts as conductive channel to accelerate electrons transfer, and the surface defects of CdSe and Schottky barrier reduce the energy loss during the electron transmission process. This work provides new insights for boosts electron transfer to improve photocatalytic performance.