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.