Enhancing visible-light degradation performance of g-C3N4 on organic pollutants by constructing heterojunctions via combining tubular g-C3N4 with Bi2O3 nanosheets

In this paper, a novel heterojunction photocatalyst was prepared by depositing Bi2O3 nanosheets on the surface of tubular g-C3N4 (TCN) using a simple solvothermal method. The photocatalytic activity was assessed using Rhodamine B (RhB) and Tetracycline (TC) as the target contaminant under visible light (λ > 420 nm). Compared with single TCN or Bi2O3, the TCN/Bi2O3 composites exhibited enhanced photocatalytic activity. The TCN/Bi2O3-0.5 photocatalyst, in particular, showed the most superior performance. Its removal efficiency of TC reached 94% in 100 min and that of RhB reached 99% in 60 min, with a rate constant (0.06532 min−1) of degrading RhB of 4.9 and 3.9 times higher than that of TCN and Bi2O3, respectively. The results of photoluminescence, photocurrent, and electrochemical impedance spectrum characterization showed that the composite photocatalysts can significantly improve the separation efficiency of the photogenerated carriers, due to the construction of heterojunctions. A possible mechanism of the degradation of target pollutants by the composite catalyst was proposed. The synergistic effect of the increased specific surface area and the heterojunction formed by interfacial contact between Bi2O3 and TCN was primarily responsible for improving photocatalytic performance.