Photocatalytic degradation of MB by lignin carbon quantum dot modified BiVO4 composites materials

Abstract Methylene blue is a significant pollutant that seriously threatens the safety of water environments, and traditional methods have difficulty in removing it. In this study, lignin carbon quantum dots (CQDs) were prepared by hydrothermal method, and a BiVO₄/CQDs composite materials was fabricated for the photocatalytic degradation of methylene blue. Through various testing methods, the optimal doping amount of carbon quantum dots was successfully studied. The doping of carbon quantum dots reduced the band gap of BiVO₄ and enhanced the light absorption and electron transfer ability of the BiVO₄/CQDs composite materials. Among them, the BiVO₄/CQDs-15 composite materials exhibited the best photodegradation effect. Under visible light irradiation, 99.7% of the methylene blue was degraded within just 120 min. The enhancement of photocatalytic activity is attributed to the highly dispersed nature of CQDs on the surface of BiVO₄, their upconversion property, excellent electron transfer ability, and the synergistic effect on the photocatalytic performance of BiVO₄.