Preparation of a direct Z-scheme thin-film electrode based on CdS QD-sensitized BiOI/WO3 and its photoelectrocatalytic performance

Abstract

To further improve the photoelectrocatalytic performance of the BiOI/WO3 thin-film electrode, a CdS QD-sensitized direct Z-scheme CdS/BiOI/WO3 ternary heterojunction thin-film electrode was prepared by the SILAR method. XRD, SEM, TEM, EDS, XPS, UV–vis spectroscopy, PL spectroscopy, EIS, and MS were used to perform phase characterization and photoelectric performance analysis of thin-film electrodes. Degradation of methylene blue solution (MB) experiments were used to explore the photoelectrocatalytic activity of thin-film electrodes. The degradation of MB by the CdS/BiOI/WO3 thin-film electrode is as high as 98.3 %, and its reaction rate constant (0.2521 min−1) is 118.4 times those of pure WO3 thin-film electrodes. The improved photoelectrocatalytic activity of the sensitized thin-film electrode is mainly attributed to the direct Z-scheme mechanism of the ternary heterojunction thin-film electrode. Compared with the traditional mechanism of BiOI/WO3 thin-film electrodes, the unique electron-hole pair migration method of the direct Z-scheme allows more photogenerated electrons and holes to participate in the photoelectrocatalytic degradation reaction and increases the active material ·O2-. This research broadens the direction for the selection of photocatalytic materials.