表面修饰对GaN:ZnO固溶体光催化性能的优化研究

It is found that the bandgap of the solid solution (GaN)x(ZnO)1-x lies in the wave band of the visible light (2.4-2.7eV), much lower than the values of semiconductor ZnO and GaN. It is thus a potential high efficient photocatalyst for hgdrogen production by water splitting and many researchers have been attracted to work in this field in recent years. But the quantum efficience at present is generally lower than 10%. By using both experimental methods and theoretical calculation, the influence of surface on photocatalysis quantum efficience will be investigated in this project. By means of surface modification we will probe to improve the carriers to shift toward surface, reduce the recombination probability of carriers on surface, and enhance the chemical stability of catalyst. The finish of this project will get a entire understanding to the role of catalyst surfce in photocatalysis process and the photocatalytic quantum efficient of (GaN)x(ZnO)1-x will be optimized probably. Thses results have academic significance and practical values. Our investigation to wide band gap semiconductor has lasted for a long time, focusing on their photonic properties, nanostructures, and surface properties, so we are familiar with GaN and ZnO. That is a good grounding for the finish of this project.

研究表明半导体GaN和ZnO组成固溶体(GaN)x(ZnO)1-x以后其带隙宽度可降至可见光波段（2.4-2.7eV），是一种潜在的高效光解水制氢催化剂，近年来吸引了众多科技工作者在从事相关研究,但目前的量子效率普遍低于10%。 本项目计划把实验方法和理论计算相结合，研究催化剂表面对光催化量子效率的影响。探索通过表面修饰促进载流子向表面扩散,降低载流子在表面的复合几率,增强催化剂的化学稳定性。项目的完成能够全面深入地认识催化剂表面在光催化过程中的作用，有望使(GaN)x(ZnO)1-x催化剂的量子效率得到提升，具有重要的学术意义和实用价值。项目组主要成员长期从事宽禁带半导体材料光学性质、纳米结构、及表面性质的研究，对GaN和ZnO的性质有深入了解，为本项目的开展奠定了良好的前期基础。

本项目从理论和实验两方面研究了表面结构对(GaN)x(ZnO)1-x固溶体光催化性能的影响，基本达到预期目标，并取得重要进展。研究发现ZnO具有不同于GaN等半导体的表面性质，ZnO的四个低指数面不能再带隙中形成孤立的表面态，因此其表面电子具有高迁移率。垂直于c轴的一对极性面能够在纳米结构中可以产生强的极化场，促使电子-空穴对分离，提高光催化效率，非极性面不具有这样的特性。在此思想的指导下，我们尝试对(GaN)x(ZnO)1-x固溶体的表面进行改性和修饰。经过大量的实验工作，最终发展出一套化学气相刻蚀的方法，能够在ZnO纳米线表面刻蚀出周期性螺纹结构的高指数面，提高极性面的比例，有利于提高其光催化效率。最后还研究了刻蚀出的高指数面可以稳定存在的物理机制。这些成果对于深入理解(GaN)x(ZnO)1-x的催化机理，进一步提高其催化性能具有重要指导作用。

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