Oxygen vacancy construction and in situ reduction of metal ions to enhance the photocatalytic performance of Bi5Nb3O15

•Oxygen vacancy and Bi coexist to improve the photocatalytic performance of Bi5Nb3O15.•Oxygen vacancy level and surface plasma resonance effect of Bi can cooperate very well.•The photocatalytic degradation process of the herbicide 2,4-D was systematically described.•The prepared photocatalyst Bi-Bi5Nb3O15-550 has better universality under visible light. Bi-Bi5Nb3O15-550 photocatalyst was successfully synthesized by high-temperature calcination and in-situ reduction. The composition and morphology of the photocatalyst were characterized by XRD, SEM, TEM and XPS. The photocatalytic degradation of herbicide 2,4-Dichlorophenoxyacetic acid (2,4-D) by Bi-Bi5Nb3O15-550 under visible light was investigated. The results show that the introduction of oxygen vacancies and the surface plasmon resonance effect of Bi can expand the absorption range of photocatalyst in the visible light region and accelerate the transport of photogenerated carriers and inhibit their recombination. After 120 min of irradiation, 15 mg of Bi-Bi5Nb3O15-550 can degrade 92.4 % of 2,4-D (20 mg/L). The degradation rate of 2,4-D is 13.6 times that of Bi5Nb3O15 without high-temperature calcination and in-situ reduction treatment. The degradation products and path of 2,4-D were analyzed by high resolution mass spectrometry. The mechanism of oxygen vacancy and reduced bismuth enhancing the photocatalytic activity of Bi-Bi5Nb3O15-550 was revealed.