氟离子对半导体金属氧化物的表面性质调控及光催化性能影响研究

Semiconductor-based photocatalysis is a promising avenue to solve the worldwide energy shortages and environmental pollution using the abundant solar light. Metal oxides are one of the most widely used semiconductor photocatalysts. Regulating the surface properties of metal oxides, improving the separation efficiency of photogenerated charges, and developing photocatalysts with high photocatalytic properties have always been the research focus in the field of photocatalysis. Surface anion engineering is an effective strategy to regulate the surface properties of metal oxides and improve their photocatalytic activities. This project intends to carry out surface fluorinion(F-) modification of semiconductor metal oxides such as TiO2, ZnO and BiVO4, rationally utilize the unique chemical and structural properties of F-, and reasonably modulate surface composition, structure, defects and other properties by controlling experimental conditions such as temperature, concentration, precursor and reaction medium. The effects of F- on the photo-generated charge separation, migration and transport of semiconductor metal oxides and their mechanisms were further studied by using transient spectroscopy and theoretical calculations, and the effective separation of photogenerated carriers was further promoted to prepare semiconductors with high photocatalytic performance. The implementation of this project can effectively solve the key scientific problems of difficult surface modulation and low photocatalytic activity of metal oxides, and it is versatile and practical in the research field of different kinds of semiconductor photocatalytic materials.

光催化技术是解决能源短缺与环境污染的有效途径。金属氧化物是当前应用最广泛的一类半导体光催化剂，调控金属氧化物的表面性质、提高光生电荷的分离效率、开发具有高效光催化性能的光催化剂一直是光催化领域的研究重点。表面阴离子工程是调控金属氧化物表面性质、提高其光催化性能的有效策略。本项目拟对TiO2、ZnO和BiVO4等半导体金属氧化物进行表面F-修饰，理性利用F-独特的化学和结构性质，通过控制温度、浓度、前驱体、反应介质等实验条件实现对金属氧化物表面组成、结构、缺陷等性质调控。采用瞬态光谱和理论计算等手段深入研究F-对半导体金属氧化物的光生电荷分离、迁移、传输影响及作用机制，进一步促进光生载流子的有效分离，从而制备具有高效光催化性能的半导体光催化材料。本项目实施可以有效解决金属氧化物表面性质难以控制及光催化活性较低的关键科学问题，并且在不同种类的半导体光催化材料研究领域具有通用性和实用性。

光催化反应一般都是在表界面处发生，调控金属氧化物半导体材料的表界面性质可以理性调变光吸收性能、光生载流子的分离及传输效率进而提升其光催化反应活性。调控金属氧化物半导体材料的表界面性质、光生电荷的分离和传输对于改性其他类型的半导体材料具有很好的借鉴意义。. 本项目采用无机氟离子为调节剂，理性改性和调控TiO2、BiVO4等金属氧化物半导体材料的表界面性质，达到调控表面原子结构、表面电子结构、表面缺陷物种和数量、光吸收和转换效率、反应物的吸附/脱附位点，进而促进光生载流子的分离、迁移及传输效率，最终提升金属氧化物半导体材料的光催化活性。具体而言，采用氟离子调控制备高指数晶面暴露的BiVO4多面体纳米单晶，研究高指数晶面、低指数晶面和表面氟离子促进光生电荷分离及传输效率的协同作用机制；采用氟离子调控和修饰TiO2的表界面性质，研究暴露活性晶面、缺陷态和不同活性晶面间的载流子迁移对光催化活性的影响机制。. 本项目以氟离子为金属氧化物表界面性质的调节器，初步阐述半导体材料表界面性质在光催化反应中的作用机制，为理性调控金属氧化物半导体材料的光吸收性能、光生电荷的分离效率和光催化转化效率提供了参考实例。