Novel visible-light-driven S-doped carbon dots/BiOI nanocomposites: improved photocatalytic activity and mechanism insight

Developing visible light-driven photocatalyst has been paid a lot of attentions due to the intention of utilizing the solar energy. In this present work, novel visible light-driven S-doped carbon dots (S-CDs)/BiOI composites were synthesized via a facile hydrothermal method and followed by a chemisorption. The S-doped carbon dots were applied in the photocatalytic reaction for the first time and show promising results. The S-CDs/BiOI composite was formed with S-CDs uniformly deposited on the surface of thin BiOI nanosheet. All S-CDs/BiOI composites exhibit higher photocatalytic degradation activities of methylene blue (MB) than pure BiOI, and the optimal modification proportion of S-CDs is 1%. And the S-CDs/BiOI composite also exhibits much higher photocatalytic activities than undoped CDs/BiOI composite. The improved photocatalytic performance of S-CDs/BiOI is attributed to the interfacial transfer of electrons from BiOI to S-CDs, resulting in a more effective charge separation and enhanced photocatalytic activity. For the photocatalytic degradation of MB, the active species trapping experiments indicate that the superoxide radical is the main active species of the S-CDs/BiOI composite. Our results suggest that sulfur doping can further improve the performance of CDs and CDs modification can effectively enhance the photocatalytic activity.