基于氯自由基链式反应的臭氧可见光消除研究

Study of Ozone Elimination via Chlorine Radical Chain Reaction Under Visible Light

随着地球大气中臭氧(O_(3))浓度的逐年升高,臭氧已成为大气污染治理的一个重要污染物.羟基自由基光催化反应对臭氧消除性能偏低,仅提高羟基自由基产量的改性方法已不适用于臭氧光催化消除.本文以Bi_(2)WO_(6)为基础,先后进行了Fe掺杂以及TiO_(2)负载,制备了一系列Fe-Bi_(2)WO_(6)@TiO_(2)复合材料,并对复合材料进行了物性表征及臭氧催化活性测试.结果表明,Fe-Bi_(2)WO_(6)@TiO_(2)材料具有典型的包覆结构,表现出可见光响应并激发了氯自由基的生成.氯自由基作为消除O_(3)的活性物种,驱动了一种类似“臭氧层空洞效应”的光化学反应机制,即表面氯化的TiO_(2)受光激发产生氯自由基,引发链式反应,大幅提升了臭氧分解的性能.Fe-Bi_(2)WO_(6)@TiO_(2)对O_(3)的消除率最大为93%.氯自由基的引入以及复合材料可见光响应的拓展,可大幅提升光催化臭氧消除能力.

The concentration of ozone(O_(3))in our atmosphere has increased,which makes O_(3)a crucial pollutant in the prevention of air pollution.The photocatalytic reaction based on hydroxyl radical has low ozone elimination perfor⁃mance,and the modification method that only increases the production of hydroxyl radical is not suitable for ozone photocatalytic elimination.In this paper,a series of Fe-Bi_(2)WO_(6)@TiO_(2)composites were prepared by Fe doping and TiO_(2)supporting successively based on Bi_(2)WO_(6).A series of physical properties characterization and ozone catalytic activity tests were carried out for the composites.The results show that Fe-Bi_(2)WO_(6)@TiO_(2)has a typical coating structure,exhibits visible light response,and stimulates the formation of chlorine radicals.Chlorine radicals act as active species for eliminating O_(3),driving a photochemical reaction mechanism similar to the"ozone hole effect",that is,the surface chlorinated TiO_(2)was photoexcited to produce chlorine radicals,triggering a chain reaction,and greatly improving the ozone decomposition performance.The maximum elimination rate of O_(3)by Fe-Bi_(2)WO_(6)@TiO_(2)is 93%.The introduction of chlorine radical and the expansion of visible light response of the composite can greatly improve the photocatalytic ozone elimination ability.