Z-scheme based CdS/CdWO4 heterojunction visible light photocatalyst for dye degradation and hydrogen evolution

In this study, the CdS/CdWO4 composites was synthesized by three steps as the visible-light-driven photocatalyst to achieve the remarkable enhanced photocatalytic hydrogen (H-2) production activity (about 2400 mu mol/h/g) and excellent photodegradation activity (97%) of malachite green (MG) in 100 min. Compared with pure CdS, 0.5-CdS/CdWO4 composites exhibit 3-fold higher photocurrent density in photocurrent response experiment and smaller charge-transfer resistance in electrochemical impedance spectroscopy (EIS) which manifested the efficacious separation of photo-generated charges. Radical trapping experiments and XPS further demonstrate the transfer of photo-generated charges followed Z-scheme system. This work presents a new design of CdS/CdWO4 composites in formation of Z-scheme heterojunction. Based on the outcomes of UV-vis spectra and Mott-Schottky plots, the photocatalytic mechanism of H-2 production and MG photodegradation over CdS/CdWO4 composites under visible-light irradiation was proposed.