光催化材料晶面控制合成及其光生电荷分离研究

The facet controlled fabrication and photogenerated charge separation have attracted considerable interest in recent years. Up to now, it was generally considered that the difference of bandgap structures may lead to the charge separation and transfer among various crystals facets. However, the effects of atom arrangement, electronegativity, and electron effective mass on the charge separation and transfer are still unclear up to now. Moreover, the present work mostly focused on the traditional TiO2 and BiVO4 materials, and the ratio of various facets is relatively simplex whether the same phenomena inhered in other material systems are still indistinct. Thereby, to address the above problems, this project focus on the exploration and fabrication of novel photocatalysts, such as Ag3PO4、Ag2WO4、SrTiO3、Cu2O, consisted of various crystal facets by a simple solution process. Furthermore, their photocatalytic properties for the splitting water and degradation of organic dyes have been studied detailedly, and the processes of charge separation as well as transfer were detected. In these novel photocatalysts, the crystal effect as well as unique energy band structure could enhance the visible light absorption, and promote the effective separation of photoexcited electron–hole pairs, which could promote the design and construction of highly efficient photocatalytic materials as well as their practical applications on solving energy crisis and environmental problems.

半导体材料晶面间光生电荷分离成为目前光催化研究领域的热点。目前研究普遍认为晶面能带结构差异是驱动光生载流子分离的主要原因，而其他因素如暴露原子不同所引起的表面电负性以及电子有效质量等作用机理研究尚未开展。此外，目前研究主要集中于TiO2、BiVO4传统材料并且其晶面组成及比例相对单一，在其他材料体系中是否同样存在晶面间光生电荷分离作用及规律尚不清楚。因此，本项目拟设计和制备具有不同晶面组成的半导体材料如Ag3PO4、Ag2WO4、SrTiO3、Cu2O等，并对其光催化分解水及降解有机污染物性能进行详细研究，从微观上认识不同晶面间的光生电子空穴分离、复合过程。利用原位表面光电子能谱、超快光谱、理论计算等手段深入研究晶面能带结构、表面电负性、原子排布及电子有效质量等因素驱动晶面间光生载流子分离的微观作用规律，为进一步拓展和开发具有高效光催化性能的半导体材料研究提供理论及实验依据。

太阳能光(电)催化分解水可以将水直接转化成清洁、可再生的氢燃料，因而是解决能源短缺、环境恶化和气候变暖等问题的最理想的技术途径之一。但是，光催化研究普遍面临光生载流子复合率严重、太阳能转化效率低等关键问题，严重制约了其实际应用。为解决上述关键科学问题，本课题主要围绕设计构建具有不同暴露晶面半导体光催化材料，研究晶面组成及比例对光催化分解水和降解有机污染物性能的影响，深入分析不同晶面在光催化反应过程中促进光生载流子分离的作用机制，从而制备具有稳定高效的半导体光催化材料。项目执行期间发展了一系列具有特定晶面及空间电荷分离功能的光催化材料，具体研究成果分为以下两个方面：1)系统研究了Bi2MoO6、TiO2、ZnO、ZnWO4等具有不同晶面结构的光催化材料，在一定程度解决了光生电子-空穴的复合以及电子迁移的难题；2）基于光激发时电子-空穴在晶面间的定向分离，通过光沉积助催化剂进一步提高光生电荷分离，从而增强光(电)催化分解水性能。在J. Mater. Chem. A, Nanoscale等期刊发表10余篇研究论文，其研究结果为半导体高效光生电荷迁移及光催化性能研究提供实验依据和理论指导。总之，本研究项目基本完成了计划书上规定的任务，达到了预期的研究目标。