Urea-modified carbon quantum dots as electron mediator decorated g-C3N4/WO3 with enhanced visible-light photocatalytic activity and mechanism insight

Abstract A novel urea modified carbon quantum dots (NCDs) decorated g-C3N4/WO3 Z-scheme heterojunction was prepared through in situ calcination and physical deposition way in the article. The analysis data of UV–vis spectroscopy demonstrated that the introduction of NCDs and the construction of g-C3N4/WO3 Z-scheme heterojunction can significantly improve the visible-light utilization. The enhanced photocurrent response and the reduced fluorescence intensity indicated the recombination of photogenerated electron-hole pairs in g-C3N4/WO3/NCDs composites is significantly inhibited. In addition, the results of cyclic experiment and the XRD diffraction peak of g-C3N4/WO3/NCDs before and after the experiment declared that g-C3N4/WO3/NCDs possess strong structural stability. Obviously, the excellent photocatalytic performance of g-C3N4/WO3/NCDs can be ascribed to the above three experimental processes. Experimental analysis of free radical capture confirmed that superoxide ion radicals (·O2−) was the main active component in photocatalytic degradation, and the possible degradation mechanism of g-C3N4/WO3/NCDs was proposed.