含缺陷Zn2SnO4可见光催化净化典型空气污染物的性能增强和反应机理研究

As one kind of green and high-efficiency technologies for potentially solving environment and energy issues, photocatalysis has been research focus. The applicants have discovered the result of defect-induced Zn2SnO4 with excellent visible-light performance by C doping. In order to solve these key scientific problems based on Zn2SnO4 with steerable concentrations of C-doping and defect, and the application of NO and formaldehyde purification under visible light illumination, this proposal is expected to study the hydrothermal synthesis conditions systematically, establishing the relationship between appropriate concentrations of C-doping and defect and efficient visible-light performance. The proposal will also investigate the formation mechanism of in-situ C-doping and defect through analyzing the changes of microstructure for solid products and composition for liquid phase products during different hydrothermal reaction steps. Additionally, the synergistic effect exerts in the photocatalytic process will be elaborated by confirmation of the form of C-doping and intermediate energy level of defect via various characterization technologies and DFT calculation. The as-prepared Zn2SnO4 will be applied into purification of NO and formaldehyde with low concentrations under visible light irradiation, respectively. Accordingly, the mechanisms of visible-light performance and reaction will be explicated by combing the analyses of the intermediate and final product during photocatalytic reaction via in situ infrared spectroscopy with the results of characterization and DFT calculation. This proposal will not only deepen the understanding on the essence of Zn2SnO4 with visible light performance, but also provide a new way in solving increasingly severe environment issues.

光催化作为一种有望解决环境和能源问题的绿色高效技术，已成为研究热点。申请者在探索中发现了通过C掺杂引入缺陷的Zn2SnO4具有优异的可见光催化活性，本项目拟在此基础上，针对该类材料可控合成和应用于可见光催化净化NO和甲醛需解决的关键科学问题，系统研究水热合成工艺条件，建立合适的C掺杂浓度、缺陷浓度与高效可见光催化性能的构效关系；动态分析并揭示水热过程不同反应阶段固相产物微结构和液相成分的变化规律，探究C掺杂和缺陷的形成机理；通过各项表征技术和DFT理论计算，确定C掺杂的形态和缺陷形成的中间能级，阐明其在光催化过程中的协同效应；将Zn2SnO4应用于低浓度NO和甲醛的可见光催化净化，结合原位红外光谱分析光催化反应生成的中间产物和终产物，综合表征与理论计算结果，明确可见光催化性能增强机制和反应机理。本项目可以加深对Zn2SnO4可见光催化本质的认识，为解决严峻的环境问题，提供新的思路。

本项目针对本征半导体光催化材料差的光催化性能，通过简单的改性策略引入空位缺陷，以实现载流子高效的迁移与分离，提高光催化活性。本项目通过一锅水热法制备了单质铋与氧空位共修饰的Zn2SnO4，实验与理论模拟计算结合考察了两者的协同机制，以此提出了一条新的电荷传输路径和独特的NO催化氧化反应机理。本项目在传统TiO2光催化材料中引入了氧空位，通过调控煅烧温度来改变氧空位的浓度；氧空位的存在不仅局域光生电子，还成为活性中心，有效地增强甲醛分子的吸附活化，存在的大量局域电子可以注入到甲醛分子中的C=O键并使其活化断裂，从而有效地减少甲醛氧化过程中甲酸的积累，加快甲醛的高效氧化去除。为了探究空位缺陷在氮化碳中的作用，采用简单煅烧法分别制备得到含碳和含氮空位的氮化碳光催化材料。表征测试与理论计算结果表明，空位缺陷作为活性中心可活化分子氧生成相应的活性氧物种，极大提升光催化氧化NO性能。本项目在前期研究基础上，还对不同光响应的光催化材料（氮化碳、铋基光催化剂、Mxenes基助光催化剂、绝缘体基光催化剂）进行了总结。项目执行期间，在本领域权威期刊发表第一/通讯作者SCI一区论文7篇，《科学通报》论文1篇，其中2篇入选ESI高被引论文，1篇入选热点论文；以第一作者申请国家发明专利2项，授权1项；获得湖北省自然科学三等奖，川渝科技学术大会二等奖；以第一作者撰写学术专著2部；培养硕士研究生6名（1名研究生获得硕士学位，获得研究生国家奖学金并被武汉理工大学录取攻读博士学位）；项目申请人应邀担任Rare Metals青年编委，Frontiers in Chemistry客座编辑，入选重庆市大气污染防治专家。