Constructing a Z-scheme ZnIn2S4-S/CNTs/RP nanocomposite with modulated energy band alignment for enhanced photocatalytic hydrogen evolution

Abstract Energy band structures greatly determine the charge separation and transfer properties in heterojunction photocatalysts and consequently their photocatalytic activities. Herein, a well-designed Z-scheme ZnIn2S4-S/CNTs/RP (ZIS-S/CNTs/RP) nanocomposite was fabricated according to an energy band alignment steering strategy to realize superior photocatalytic H2 evolution performance. The ZIS-S/CNTs/RP nanocomposite shows an efficient photocatalytic H2 evolution rate of 1639.9 μmol g-1 h-1, which is noticeably higher than that of pristine red phosphorus (RP) and CNTs/RP and ZIS-S/RP composites, as well as those of the compared heterojunctions using bulk RP or ZnIn2S4. Owing to the modification of nanosized RP and the introduction of sulfur vacancies in ZnIn2S4, a tailored energy band alignment of the heterojunction with a higher reduction potential and larger Fermi level potential difference was achieved, which resulted in significantly increased photogenerated electron-hole separation efficiency and a more efficient Z-scheme charge transfer mechanism, thus promoting the photocatalytic activity of ZIS-S/CNTs/RP. This work aims to provide a novel effective strategy for the construction of high-performance heterojunction photocatalysts by energy band engineering.