In2O3{111}和{001}晶面的新型同质结的设计、制备及其光电化学催化性能研究

Semiconductor nanostructures enclosed by crystal facets have been widely employed in photoelectrochemical water splitting because of unique crystal facet effect. However, it is still necessary to further promote the photogenerated charge separation efficiency owing the weakness in their structures. Thus, design and fabrication of novel and efficient photoelectrochemical catalytic materials based on the crystal facet effect have become an important research direction. Based on our recent work on the controlled growth of various In3O3 nanostructures, this project firstly aims to design and fabricate a novel homojunction consisting of square In2O3 nanowires with exposed {001} facets and octahedron with exposed {111} facets on conductive substrate to disclose its growth mechanism. Based on the above research, we further deeply discuss the separation, trapping, transportation mechanism of the photogenerated electron-hole pairs in the crystal facet-based homojunction via studying relation between its structure and photoelectrocatalytic performance. In addition, we will design the wireless solar water splitting device by the integration of In2O3 crystal facet-based homojunction photoanode, a double-junction a-Si (2-jn a-Si) solar cell and Pt. Such device mimics the photosynthetic process within a leaf that converts the energy of sunlight into chemical energy by splitting water to produce O2 and hydrogen equivalents. This project provide a new strategy to promote the electron-hole pairs separation, which is expected to efficiently improve photoelectrochemical catalytic performance.

有规则表面的半导体纳米材料具有奇特的晶面效应，在光电化学催化领域应用广泛。然而由于结构缺陷的存在，光生载流子的分离效率仍有待提高，因此设计和制备新型高效的同晶面效应相关的光电催化材料是目前一个重要研究方向。本项目以我们前期对多种In2O3纳米结构研究为基础，在导电基片上直接生长一种新型晶面基同质结构，即在暴露{001}晶面的方纳米线表面选择性地外延生长暴露{111}晶面的纳米颗粒形成同质结构，探索这种新型晶面基同质结的制备方法和生长机制；揭示该体系和光电化学催化性能的构效关系，阐明光生载流子在不同形貌纳米结构的不同晶面间的分离、复合及迁移机制；将In2O3晶面基同质结和负载析氢助催化剂的双结非晶硅薄膜太阳能电池通过导电基片集成于一体，设计新型无导线光电化学水分解器件，使其类似树叶一样具有太阳能捕获和转换的功能。本项目提供了一种促进光生载流子分离的新途径，期望能有效地提高光电化学催化性能。

针对有规则晶面的半导体纳米材料在光电催化过程中光生载流子易于复合的难题，本项目利用改进的化学气相沉积设备，通过改变不同生长时期的生长温度在暴露{001}晶面的In2O3方形纳米线表面外延生长暴露{111}晶面的八面体纳米颗粒形成新型项链状晶面基同质结；通过研究生长参数（如反应温度、反应时间、载气配比等）对暴露特定晶面In2O3纳米结构形貌演化的影响，揭示其成核和生长机制；通过研究所制备新型晶面基同质结的形貌、微观结构、界面处晶格匹配信息、光吸收特性、晶体结构、能带结构和光电催化性能等特性，阐明光生载流子的在晶面基同质结中的分离、复合及迁移机制；提出一步化学气相沉积法，在暴露{001}晶面的方形纳米线表面引入氧空位，揭示氧空位的数量与可见光光电催化活性的规律，阐明晶面效应和氧空位协同增强光电催化性能的机制；另外，本项目拓展研究了其它具有特殊结构半导体材料和高效阴极析氢材料，为“人造树叶”光电器件的设计和制备做出了有意义地探索。本项目提供了几种促进光生载流子分离的新思路，对于太阳能的转换和存储及氢能源的制备具有重要的学术价值。