Synergistic Enhancement Of Photocatalytic Activity Of Bismuth Niobate By Oxygen Vacancy Construction And In Situ Reduction Of Bismuth Metal

In the face of increasingly prominent environmental problems,it is particularly important to fight the battle of pollution prevention and develop green and sustainable environmental purification technology.As an advanced oxidation technology,photocatalysis has the advantages of low energy consumption,simple operation and no secondary pollution.The development of photocatalyst with excellent performance is the first choice in the field of photocatalysis to control environmental pollution.Bismuth niobate(Bi₅Nb₃O₁₅)is considered as a potential photocatalyst due to its excellent stability and photoelectric properties.However,the narrow optical absorption range of Bi₅Nb₃O₁₅ and the high photocarrier recombination rate limit the practical application of Bi₅Nb₃O₁₅ in the field of photocatalysis.Herein,two modification strategies of Bi₅Nb₃O₁₅ were applied to the modification of Bi₅Nb₃O₁₅ for the first time.The synergistic effect of oxygen vacancy and metal Bi can not only effectively broaden the optical absorption range of Bi₅Nb₃O₁₅,but also improve the separation and transmission rate of photogenerated electrons and holes in Bi₅Nb₃O₁₅,and significantly enhance the photocatalytic performance of Bi₅Nb₃O₁₅.Specific work is as follows:（1）Bi₅Nb₃O₁₅ photocatalyst,Bi₅Nb₃O₁₅-550 photocatalyst rich in oxygen vacancy and Bi-Bi₅Nb₃O₁₅-550 photocatalyst with oxygen vacancy co-existing with metal Bi were prepared by solvothermal method,high temperature calcination method and in-situ reduction method.The photocatalyst was characterized by XRD,XPS,SEM,TEM,HRTEM and ESR.The effects of oxygen vacancy content on the photocatalytic performance of Bi₅Nb₃O₁₅-550 and metal Bi content on the photocatalytic performance of Bi-Bi₅Nb₃O₁₅-550 were investigated using phenol as a probe.（2）The photocatalytic degradation properties of Bi₅Nb₃O₁₅,Bi₅Nb₃O₁₅-550 and Bi-Bi₅Nb₃O₁₅-550 to 2,4-dichlorophenoxyacetic acid（2,4-D）were investigated.The active species of Bi-Bi₅Nb₃O₁₅-550 in the photocatalytic degradation of 2,4-D were determined by free radical capture experiment,and the products and degradation paths of Bi-Bi₅Nb₃O₁₅-550 photocatalytic degradation were analyzed by high resolution mass spectrometry.（3）The possible mechanism of enhanced photocatalytic performance of Bi-Bi₅Nb₃O₁₅-550photocatalyst was proposed by analyzing the photoelectric performance,ultraviolet photoelectron spectroscopy and energy band location.