论文摘要：Regulation of the carrier migration path in heterojunction photocatalysts is an effective strategy to improve the performance of photocatalytic hydrogen evolution. Herein, CdS/CdWO4 heterojunction photocatalysts based on two crystal forms of CdWO4 were synthesized via an in-situ anion-exchange reaction. It was discovered that crystal structure and surface defect have a significant impact on the charge carrier migration mechanism during photocatalysis. When CdS was loaded onto monoclinic CdWO4 (M-CdWO4), the resulting CdS/M-CdWO4 heterojunction followed the conventional type- II charge transfer mechanism. In contrast, tetragonal CdWO4 (T-CdWO4) with a substantial number of oxygen vacancies resulted in the CdS/T-CdWO4 composite adopting an S-scheme transport mechanism. Driven by the distinct carrier migration path, the CdS/T-CdWO4 heterojunction demonstrated superior hydrogen evolution performance compared to the CdS/M-CdWO4. Significantly, the hydrogen evolution rate of CdS/T-CdWO4 was 2.56 mmol h−1 g−1, which is about 14 times higher than CdS/M-CdWO4. The excellent photocatalytic activity of CdS/T-CdWO4 could be mainly ascribed to the efficient separation of photogenerated charge carriers and the higher reduction capacity showcasing in S-scheme. Several techniques such as electron paramagnetic resonance (EPR), in-situ X-ray photoelectron spectroscopy (XPS), and selective photodeposition were employed to confirm the regulation of the carrier migration path from type II to S-scheme over CdS-loaded CdWO4 polymorphs. This study provides comprehensive insights into the construction of highly efficient photocatalytic heterojunctions in the viewpoint of polymorph engineering and surface defects from a deeper perspective.
论文链接：https://www.sciencedirect.com/science/article/pii/S0021951724000319