可见光活化分子氧产生羟基自由基降解有机污染物的新途径

OH是高反应活性瞬态物种，是消除水中顽固有机污染物的理想氧化剂，但其产生需要高能紫外光和分解高能试剂(H2O2,O3)。BiOX能有效利用可见光，通过调控带结构中O2p 与X np杂化方式，有可能用低能量可见光将O2活化成 OH。本项目以具有确定组成和晶型的BiOX1(n)X2(1-n)（X1,2=F,Cl,Br,I）为光催化剂，选择高于和低于价带氧化电位的不同污染物为底物，运用NMR、LC-MS和GC-MS等手段分析底物发生羟基化、脱羧反应的中间产物，采用同位素标记技术确定氧归属，结合ESR和In-Situ-IR手段，考察和筛选在可见光激发下能高效率将O2转化成 OH的催化剂带组成和带结构，通过改变O2p与Xnp在带结构中的比率及单一X1到二元混合体系X1(n)X2(1-n) 带组成来确定 OH产率的关键因素，提供一类低能量累积导致高能氧化物种降解水中有机污染物的新途径。

Hydroxyl radical(oOH), a kind of transient species with high reaction activity, is an optimal oxidant to eliminate pernicious organic pollutants in water. But the product of oOH largely depends on the decomposition of reagents (H2O2,O3) and the irradiation of ultraviolet with high energy. Bi-based halogen oxides (BiOX) can efficiently use visible light. It is possible to activate molecular oxygen (O2)to oOH by regulating the hybridization form of O 2p and X np under low energy visible light irradiation. Bi-based oxyhalide BiOX1(n)X2(1-n) (X1,2 = F, Cl, Br, I) with identified composition and crystalline are used as photocatalyst to degrade different pollutants, which have higher or lower oxidation potential than the valence band of catalysts. NMR, LC-MS and GC-MS are employed to analyze the intermediate products in hydroxylation and decarboxylic reaction. Isotope labeling technique is used to determine the fate of oxygen. The band composition and structure of catalysts which can high-efficiently activate O2 to oOH are tested using ESR and In-Situ-IR techniques. The key factors of the oOH yield are investigated by changing the ratio of O 2p and X np in the band structure and composition from single X1 to binary hybrid system X1(n)X2(1-n). This method is hopeful to provide a novel approach for the degradation of organic pollutants in water by means of the accumulation of low energy to high-energy oxidatant species.