Carbon dots driven directional charge migration on sulfur vacancy enriched ZnIn2S4 nanosheets for enhanced photocatalytic hydrogen evolution

Sulfur vacancy as a kind of intrinsic defect for metal sulfides plays an important role in adjusting the electronic structure, but the uncontrollability of the regulation does not always lead to efficient activity in photocatalytic hydrogen production. To address this issue, a photocatalytic nanocomposite is designed and constructed by in situ inserting carbon dots (CDs) into ultrathin ZnIn2S4 (ZIS) nanosheets with sulfur vacancies (CDs/Vs-ZIS) by a one-step hydrothermal method. The charge transfer kinetics analysis of CDs/Vs-ZIS demonstrates that the trapped electrons by sulfur vacancies are directed transferred to the surface of CDs. The electron sink effect leads to further enhancement of the charge separation efficiency on CDs surface and CDs act as hydrogen-producing active sites to greatly improve the hydrogen evolution. Benefiting from the directional charge migration driven by CDs in Vs-ZIS nanosheets, the optimal CDs/Vs-ZIS photocatalyst exhibits a superior photocatalytic hydrogen evolution rate of 5.93 mmol g−1 h−1.