Visible-light-driven nitrogen-doped carbon quantum dots decorated g-C3N4/Bi2WO6 Z-scheme composite with enhanced photocatalytic activity and mechanism insight

In this work, the g-C3N4/Bi2WO6 Z-scheme composites were synthesized by in-situ calcination and hydrothermal method and the novel g-C3N4/Bi2WO6/NCQs was constructed by introducing nitrogen-doped carbon quantum dots (NCQs) on the interface of g-C3N4/Bi2WO6 catalyst. UV–vis spectroscopy data showed that the improved visible light utilization efficiency of the catalyst is attributed to the composition of g-C3N4/Bi2WO6 Z-scheme heterojunction and the addition of NCQs. Photocurrent response analysis and fluorescence intensity measurements showed that the high separation efficiency of photogenerated electron-hole pairs in the g-C3N4/Bi2WO6/NCQs composite. In addition, the excellent structural stability of g-C3N4/Bi2WO6/NCQs can be proved by the analysis data of cycle experiments and XRD diffraction peaks of catalysts before and after experiments. Obviously, the above experimental data and analysis demonstrated the outstanding photocatalytic activity of g-C3N4/Bi2WO6/NCQs. Free radical capture experimental data analysis confirmed that superoxide ion radicals (·O2−) and holes (h+) play a major role in the reaction process, and the possible photocatalytic mechanism of g-C3N4/Bi2WO6/NCQs was proposed to further understand its enhanced photocatalytic activity.