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

• Published in: Applied surface science 2023-10, Vol.635, p.157762, Article 157762
• Main Authors: Yu, Kai, Li, Zenan, Zhang, Tianyang, He, Tiwei, Fan, Zhenglong, Huang, Hui, Liao, Fan, Liu, Yang, Kang, Zhenhui
• Format: Article
• Language: English
• Subjects: Carbon dots; Photocatalytic hydrogen evolution; Sulfur vacancy; Transient photovoltage; ZnIn2S4
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2023.157762

Well-designed CDs-coupled sulfur vacancy enriched ZnIn2S4 nanosheet (CDs/Vs-ZIS) has been developed as an efficient photocatalyst for hydrogen evolution reaction. The trapped photogenerated electrons by sulfur vacancies migrate directionally to the surface of CDs. The electron sink effect leads to further enhancement of the charge separation efficiency, which greatly improves the hydrogen evolution on CD active sites. [Display omitted] •The CDs/Vs-ZIS nanocomposite exhibits excellent photocatalytic hydrogen evolution performance.•The sulfur vacancies serve as electron trapped centers and prolong the carrier lifetime.•CDs as electron sink effectively facilitate the charge separation.•The CD subunits in Vs-ZIS nanosheets boost the separation and transport of charge carriers. 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−1h−1.