Promoting Charge Separation in Hollow-Structured C/MoS2@ZnIn2S4/Co3O4 Photocatalysts via Double Heterojunctions for Enhanced Photocatalytic Hydrogen Evolution

A reasonable design of samples with efficient spatial separation for photoinduced electron-hole pairs toward the photocatalytic hydrogen evolution reaction (HER) has gained significant attention. Herein, a new C/MoS2@ZnIn2S4/Co3O4 composite with a core-shell structure is designed toward photocatalytic hydrogen production on C/MoS2 and Co3O4 dual electron collectors. Co3O4 nanoparticles as the co-catalyst would form a Schottky junction with ZnIn2S4 nanosheets while the C/MoS2 hollow core would form the step-scheme (S-scheme) heterojunction with ZnIn2S4 sheets, which provides a dual photogenerated electron transfer pathway during the light irradiation process. In addition, the unique core-shell architecture offers large contact interfaces favoring the exposure of rich active sites, which facilitated the separation and the transfer of charges. Consequently, all these factors endowed the C/MoS2@ZnIn2S4/Co3O4 composite with enhanced light absorption ability and an increased hydrogen evolution rate of 6.7 mmol·g-1·h-1 under 420 nm light irradiation, which is about 23.4- and 4.5-fold that of ZnIn2S4 and CMZ, respectively. This work offers a guideline for designing efficient composite photocatalysts toward the photocatalytic HER.