光催化降解气相有机物的同步辐射原位红外光谱研究

In-situ IR technology is one of the most important methods in the study of surface, adsoption/desorption and the intermediates in photocatalytic degradation of volatile organic compounds. However, the brightness of ordinary light source is not high enough for the investigation of weak-bond adsorption in the far-infrared region from 400 cm-1 to 10 cm-1 and the detection of some intermediates in the mid-infrared region. In this proposal, a method of synchrotron radiation in-situ IR was provided for the study of photocatalytic degradation of volatile organic compounds. As a result, high signal-to-noise can be obtained in infrared spectroscopy, especially in the far-infrared range. The photocatalytic degradation of gaseous toluene and formaldehyde over TiO2 will be investigated by using synchrotron radiation in-situ IR. The structure of active adsorption sites can be descripted by the identification of the weak-bond from 400 cm-1 to 10 cm-1. The relationship between the structure of adsorption sites and photocatalytic activity will be discussed as well. Furthermore, the mechanism and kinetics of photocatalytic degradation of gaseous toluene and formaldehyde will be proposed by analysis of the intermediates in the photocatalytic process under the different humidity levels, temperatures and initial concentrations. Based on these, we can safely expect that this novel method, the application of synchrotron radiation in-situ IR in photocatalytic degradation of volatile organic compounds will provide some insight into the photocatalyst preparation and photocatalytic degradation of volatile organic compounds.

利用原位红外光谱观察光催化剂表面性质、吸脱附及中间产物的种类和变化，是光催化降解气相有机物机理研究的重要手段之一。然而常规红外光谱的光源亮度低，无法有效检测远红外400～10 cm-1区域的弱键吸附和跟踪中红外波段的某些低浓度的中间产物，因此一定程度上限制了其在该领域深入研究中的应用。本项目拟以高亮度的同步辐射代替常规光源应用于红外光谱，建立光催化降解气相有机物的同步辐射原位红外光谱研究系统和方法，有望大幅提高光谱尤其是远红外波段的信噪比。在此基础上，研究气相甲苯和甲醛在TiO2表面的吸附和光催化降解。通过判定远红外400～10 cm-1区域的弱键特征吸附，揭示甲苯和甲醛在光催化剂表面活性位吸附的配位结构，构建吸附类型与光催化效率的关系；通过获取中红外波段光催化降解甲苯和甲醛的中间产物信息，阐明反应机理和动力学，为光催化剂的合成以及光催化降解气相有机污染物技术提供新的思路。

常规红外光谱的光源亮度低，无法有效检测远红外区域的弱键吸附和跟踪中红外波段的某些低浓度的中间产物，限制了其在光催化降解气相有机物机理研究中的应用。本项目建立了光催化降解气相有机物的同步辐射原位红外光谱研究系统和实验方法，利用高亮度同步辐射红外光谱深入研究了不同反应条件下，TiO2光催化降解气相甲苯（芳烃类代表VOCs）和甲醛（链烃类代表VOCs）过程中活性吸附位、表面吸附以及中间产物的种类和变化，探索了光催化降解气相有机物的机理和反应动力学。其中，判定了气相气相甲苯在TiO2表面的弱键吸附结构；阐明了酸/碱气氛修饰TiO2的表面活性位、甲苯吸附构型与光催化活性的关系；揭示了不同晶面对TiO2吸附、光催化降解气相甲苯影响的机制；实现了多组分光催化剂的快速筛选和（同步辐射）红外显微光谱分析。这些工作丰富了弱键吸附理论，揭示了高效降解VOCs的光催化剂所应具备的表面结构，为气相降解光催化剂的合成提供了一些理论依据。项目执行期间，共计发表SCI学术论文12篇，申请专利2项。参加国际学术会议3次（口头报告2次）、全国学术会议6次（口头报告3次）。