半导体纳米阵列晶面间载流子迁移与光催化性能研究

Photocatalysis could serve as one of the most potential technique to solve current energy and environmental crisis. However, the relatively high probability of photo-generated electron-hole recombination greatly limits its practical applications. Thus, promoting the separation of charge carriers and developing correlative theories on designing highly efficient photocatalysts with highly efficient separation of charge carriers are very important for the further development and practical applications of photocatalytic technologies. To address this issue, this project focuses on the exploration and fabrication of novel semiconductor nanoarrays consisted of different facets based on the anisotropic growth of crystals by adjusting the reaction parameters such as temperature, precursors, and mediums. Furthermore, the photoinduced charge separation between different crystal facets is studied by in-situ XPS, ultra-fast spectra, and theoretical calculations, and the causations for their charge separation are explored detailedly. On the basis of the results of charge separation, the ratios of different facets on the semiconductor nanoarrays are rationally adjusted and deposited with suitable co-catalysts to further enhance their photocatalytic and photoelectrochemical performances. Thereby, this project could effectively resolve the key problems of photoexcited electron–hole combination, and this strategy can be applied in many semiconductor nanoarray systems.

光催化技术是解决目前能源短缺和环境污染的有效手段之一，然而目前光催化材料较高的光生电子-空穴复合问题严重限制了其在实际生活中的大规模应用。因而，如何有效抑制光生载流子的复合，发展有利于载流子分离的光催化材料设计理论，对推动光催化技术的发展及其实际应用具有重要的科学意义。本项目拟利用半导体纳米晶体生长各向异性的规律，通过控制温度、前躯体、反应介质等合成条件，制备具有不同晶面组成及比例的半导体纳米阵列材料。利用原位光电子能谱、超快光谱、理论计算等技术对其晶面间光生载流子分离作用进行系统分析，深入研究晶面对光生电子-空穴迁移和分离的驱动因素。根据载流子在不同晶面间迁移及分离研究结果，合理调控晶面组成及选择性沉积助催化剂，从而制备具有高效光催化及光电催化性能的纳米阵列材料。此项目实施可以有效解决光生电子-空穴快速复合关键科学问题，并且在不同种类的半导体材料研究领域具有较高的通用性和实用性。

光生载流子复合率严重、太阳能转化效率低等严重制约了太阳能光(电)催化发展及其实际应用。为解决上述关键科学问题，本课题主要围绕设计构建高度有序半导体纳米阵列如纳米棒、纳米板、纳米片等，深入研究了纳米阵列晶面间光生电子-空穴迁移及其驱动因素，从而构建具有高效光电催化性能的半导体纳米阵列体系，这些研究结果对于有效推动光催化技术的发展及其实际应用具有重要的科学研究意义。项目执行期间制备了一系列具有特定晶面结构的半导体纳米阵列材料并对其光生电荷迁移进行了详细研究，具体研究成果分为以下两个方面：1)系统研究了半导体纳米阵列材料晶面可控合成，深入研究晶面在促进光生电子-空穴分离及迁移过程中的作用规律；2）在半导体纳米阵列晶面控制合成基础上选择性修饰助催化剂，进一步促进光生电子-空穴分离同时加速分解水反应速率，从而大幅度提高半导体纳米阵列光催化及光电催化性能。项目执行期间在Angew. Chem. Int. Ed.; Adv. Funct. Mater; Nano Energy期刊发表20余篇研究论文，其研究结果为提高半导体纳米阵列光生电荷迁移及光电催化性能研究提供了相应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及预期研究目标。