催化剂表面异相结与光催化性能构效关系的研究

Photocatalytic technology used by semiconductor photocatalyst is believed to be one of the effective methods to deal with energy crisis and environmental problem, and it has drawn much attention in many countries. Photogenerated electron-hole separation is one of the key factors for photocatalytic activity on semiconductor-based photocatalysts. Therefore, improving the efficiency of charge separation of the photocatalyst is one of the problems need to be solved in photocatalysis. Fabrication of phase junctions (the interface between two crystalline phases of semiconductor) on the surface of the photocatalyst is expected to be an efficient strategy for improving the performance of photocatalyst, because the junction might be helpful for charge separation. Therefore, it is of significance in designing and fabricating the highly efficient photocatalyst with phase junction. However, some issues such as structure-photocatalytic activity relationship for the surface phase junction in the photocatalyst still needs further investigation. Based on our preliminary findings, TiO2 and Bi2O3 was selected as photocatalyst, respectively, in this project. We plan to prepare the TiO2 or Bi2O3 photocatalysts with different phase junction forms as model catalysts. Combined with photocatalytic activity of photocatalytic degradation of RhB reaction over these catalysts, the influence of the form of the phase junction on the photocatalytic activity could be investigated. The contributions of the composition ration and the particle size of the two crystalline phases in the phase junction, which is formed on the surface of the photocatalyst, and the bulk structure of the photocatalyst on the efficiency of charge separation, and the photocatalytic activity could be evaluated. These works are helpful in designing and development of highly efficient catalyst systems with phase junction for photocatalytic reactions.

以半导体为催化剂的光催化技术是解决能源危机和环境污染的有效手段之一，受到世界各国的高度关注。实现光催化剂中光生电子和空穴有效分离，是提高光催化性能的主要途径之一，也是光催化领域亟待解决的关键科学问题之一。半导体“异相结”（同一材料不同晶相之间的界面）的形成能显著提高光催化剂的电子-空穴分离效率。因此，设计、构建高效异相结催化剂具有重要的科学意义。但是，异相结形式与光生电子-空穴分离效率、光催化性能之间的构效关系目前尚不清楚。在已开展的研究工作基础上，本项目选择TiO2和Bi2O3两种催化剂，可控制备不同形式的模型异相结催化剂，通过比较模型催化剂的光催化降解罗丹明B性能，研究异相结的形式与光催化性能的关系，及其在催化剂表面形成异相结的两种晶相的比例、晶粒尺寸，催化剂体相结构等与光生电子-空穴分离效率和光催化性能之间的关系。本项目的开展可以为设计和研发高效异相结光催化剂提供理论指导。

积极开发和利用太阳能是国家能源战略的重大需求，而光催化是太阳能利用的一个重要途径。实现光催化剂中光生电子和空穴的有效分离，是提高光催化性能的主要途径之一，也是光催化领域亟待解决的关键科学问题之一。我们以往的研究结果表明，半导体“异相结”结构（同一材料不同晶相之间的界面）的形成能显著提高光生电子-空穴分离效率。但并不是所有“异相结”结构都能有效发挥作用，而且其光生电荷分离效率仍然不够理想，这主要是缺少对“异相结”体系的精确、可控设计。本项目选择TiO2和Bi2O3两种催化剂，可控制备了不同形式的模型“异相结”催化剂，对“异相结”体系进行了可控设计：i) 研究了“异相结”两种晶相比例对光生电荷分离性能的影响； ii) 基于粒径对半导体能带弯曲的影响，对“异相结”中内建电场的驱动力进行了调控；iii) 在“异相结”体系中构筑了原子级的梯度传递链，极大的提升了光生电荷迁移效率，进而数量级的提升了光催化效率。这些工作不仅实现了“异相结”体系的精准设计，重要的是，进一步又将“异相结”结构逐步发展为“同相结”、“异相-同相增强结”以及“原子级同素结”等，形成了系列“相结”策略，相关研究为认识光生电荷分离这一前沿基础科学问题提供了新的思路，并且已在规模化废水深度处理中展现出良好的应用前景（辽宁省科技进步二等奖）。相关研究成果先后发表在ACS Catalysis（“研之成理”报道）, Journal of Materials Chemistry A（封底文章）, Chemical Communication（封面文章，"RSC皇家化学会"推送报道）, Applied Catalysis B: Environmental, ChemCatChem(Wiley Advanced Science News中国报道)等期刊，申请中国发明专利5项，授权中国发明专利3项。在国际催化大会、全国催化会议等国内外顶级会议上做报告。关于“异相-同相增强结”的工作入选了17届国际催化大会口头报告。项目负责人入选国务院政府特殊津贴专家、辽宁省优秀专家、辽宁省“兴辽英才”科技创新领军人才，辽宁省百千万人才工程“百”层次等。培养研究生11名，1名获辽宁省优秀硕士论文，1名获辽宁省优秀硕士论文提名。