Bi2O3 and g-C3N4 quantum dot modified anatase TiO2 heterojunction system for degradation of dyes under sunlight irradiation

A facile and feasible method was successfully utilized to incorporate Bi2O3 and g-C3N4 quantum dots on TiO2 surface to synthesize a novel composite g-C3N4/TiO2/Bi2O3. The photocatalytic activity of the composite g-C3N4/TiO2/Bi2O3 for degradation of dyes under sunlight and UV light irradiation was evaluated. It possessed the higher photocatalytic performance than that of pristine TiO2 or g-C3N4 under the same conditions. Under sunlight irradiation, the reaction rate constants of the g-C3N4/TiO2/Bi2O3 was about 4.2 times and 3.3 times higher than that of TiO2 and g-C3N4, respectively. The promising photocatalytic performance was attributed to the broader light absorption range and efficient separation of photoinduced carriers. Moreover, based on the TEM, XPS, XRD, UV-vis spectrum, radicals scavenging test and Mott-Schottky analysis systematic mechanism for photodegradation process was proposed. This work provides a promising strategy for the modification of TiO2-based semiconductors by incorporating different quantum dots and promoting the efficiency of the photocatalysts in practical application.