In the S-scheme heterojunction, photogenerated electrons from the oxidation photocatalyst recombine with holes from the reduction photocatalyst, enhancing redox potential and boosting photocatalytic activity. However, the recombination mechanism at these interfaces remains largely unexplored. In this study, we design a Cd 0.9 Zn 0.1 S/ZnWO 4 (CZS/ZWO) S-scheme heterojunction model guided by theoretical predictions. Remarkably, a nano-tetrapod-shaped CZS/ZWO S-scheme heterojunction is synthesized via a simple solvothermal and ultrasonic self-assembly method, achieving hydrogen evolution performance under visible light irradiation for 3 h that is 3.69 times higher than CZS alone and 4.63 times higher than ZWO alone. Further theoretical calculations simulate the charge transfer mechanism, electron density localization, and transition states in the photocatalytic hydrogen evolution reaction. Finally, integrating theoretical and experimental data, an S-Zn channel is proposed within the CZS/ZWO S-scheme heterojunction, clarifying the electron transfer pathway. This study provides a detailed understanding of charge transfer dynamics in S-scheme heterojunction.
One-dimensional hetero-structured nanofibers (NFs) have recently received great attention because of their rich architectures and potential applications in the field of gas sensors. Polyoxometalate (POM) is a unique nanosized transition metal-oxygen cluster used as a molecular platform to prepare metal oxide nanomaterials and accompanied by high negative charges that readily combine with various metal oxide precursors to form metal oxide complexes. Herein, with the assistance of POM, ZnWO 4 /ZnO hetero-structured NFs were prepared by combining facile electrospinning with thermal oxidation . Adjusting the molar ratio of POM (H 3 PW 12 O 40 ·xH 2 O, denoted as PW 12 ) and Zn(NO 3 ) 2 ·6H 2 O (denoted as Zn 2+ ) in the precursor solution , a series of ZnWO 4 /ZnO hetero-structured NFs were obtained. Compared with pure ZnO NFs, the optimized ZnWO 4 /ZnO hetero-structured NFs demonstrate more excellent sensing performance. A high relative response of 108.5 was achieved for 50 ppm triethylamine (TEA) and with a low detection limit about 150 ppb. Furthermore, the ZnWO 4 /ZnO hetero-structured NFs exhibited remarkable TEA selectivity and outstanding reproducibility. The enhanced sensing mechanism toward TEA could be attributed to n-n heterojunctions with the obvious barrier-control electron transfer effect at the interface between ZnWO 4 and ZnO.
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