Carbon-Dots-Modified Hierarchical ZnIn2S4/Ni–Al LDH Heterojunction with Boosted Charge Transfer for Visible-Light-Driven Photocatalytic H2 Evolution

The construction of a heterojunction structure is considered a significant route to promote solar-driven H2 production. Herein, a CDs/ZnIn2S4/Ni-Al LDHs (CDZNA) ternary heterojunction was elaborately constructed via the in situ growth of ZnIn2S4 on Ni-Al LDHs with the incorporation of carbon dots (CDs) cocatalyst, which was used as a highly efficient catalyst for the photocatalytic H2 generation. Characterizations indicated that 2D ZnIn2S4 nanosheet homogeneously dispersed on the surface of Ni-Al LDHs fabricated an intimate hierarchical architecture and provided a high BET surface area (135.12 m2 g-1). In addition, the unique embeddable-dispersed CDs as electron mediators possessed numerous active sites and promoted the charge separation on ZnIn2S4/Ni-Al LDHs (ZNA) binary catalyst. By coupling these two features, the CDZNA catalyst exhibited a considerable H2 production rate of 23.1 mmol g-1 h-1 under visible-light illumination, which was 16.4 and 1.4 times higher than those of ZnIn2S4 and ZNA, respectively. A proposed mechanism of photocatalytic H2 production over the CDZNA catalyst was also discussed. This work provides a promising strategy to achieve highly efficient solar energy conversion in a ternary photocatalytic system.