Electronic Structure\nand Photocatalytic Activity of\nDual <i>Z</i>‑Scheme CdS@Bi<sub>2</sub>S<sub>3</sub>–MoS<sub>2</sub> Heterostructures with a Full Spectrum

Two-dimensional Bi<sub>2</sub>S<sub>3</sub> is considered\na better\nphotocatalyst when combined with CdS. To deeply understand electronic\nstructures between CdS and Bi<sub>2</sub>S<sub>3</sub>, CdS@Bi<sub>2</sub>S<sub>3</sub> core–shell nanorods (NRs) were synthesized\nwith a two-step hydrothermal method, and CdS@Bi<sub>2</sub>S<sub>3</sub>–MoS<sub>2</sub> composites were obtained with MoS<sub>2</sub> nanoparticles decorated on the surface of CdS@Bi<sub>2</sub>S<sub>3</sub> NRs. Then, the energy band alignments in CdS@Bi<sub>2</sub>S<sub>3</sub>–MoS<sub>2</sub> were constructed from XPS and\nUPS measurements, and dual <i>z</i>-scheme CdS@Bi<sub>2</sub>S<sub>3</sub>–MoS<sub>2</sub> heterostructures were confirmed\nfrom charge transfer with electron spin resonance (ESR) signals of\n•O<sub>2</sub><sup>–</sup> and •OH. Finally,\nthe photocatalytic hydrogen activities were carried out with the prepared\nsamples. The results showed that the optimized CdS@Bi<sub>2</sub>S<sub>3</sub> core–shell NRs have a hydrogen production rate of\n4.29 mmol·h<sup>–1</sup>·g<sup>–1</sup>, which\nis 8.4 times higher than that of the pure CdS nanorods, and the optimized\nCdS@Bi<sub>2</sub>S<sub>3</sub>–MoS<sub>2</sub> heterostructure\nhas a hydrogen production rate of 8.72 mmol·h<sup>–1</sup>·g<sup>–1</sup>, which is 17 times higher than that of\nthe pure CdS NRs. The enhanced photocatalytic activity can be ascribed\nto the dual <i>z</i>-scheme heterostructure and full-spectrum\nabsorption; the former is favorable for the efficient separation of\nthe photogenerated electron–hole pairs, and the latter is beneficial\nto the production of more photogenerated carriers. The studies will\nbe helpful to understand the electronic structures of Bi<sub>2</sub>S<sub>3</sub> and the related heterostructures.