基于能带结构理论的半导体光催化材料改性策略

摘要

Design and controllable synthesis of catalyst and its property tuning are an interesting subject for physical chemistry, materials chemistry and catalytic chemistry. As a new environmental-purifying technology, semiconductor photocatalytic oxidation technology has arosen worldwide attention. However, conventional photocatalyst exhibits poor utilization of solar energy and low efficient of photogenerated charge separation, which restricts the practical application of the technology. Therefore, it is still a challenging topic to design and synthesize visible-light-response photocatalytic materials with higher utilization efficiency of solar energy. Be-sides tuning synthesis method (by controlling particle size, morphology, crystallinity and other microstructures, etc), modification is a crucial strategy for the activity enhancement of photocatalyst. In this paper, we reviewed the basic mechanism for the photocatalyst modification from the view of semiconductor energy structure. Taking consideration of the basic mechanism and process of photocatalysis, there are two key modification strategies: chemical structure modification (energy band modification) to broaden the light absorption and surface modifi-cation (surface sensitization, semiconductor combinations and noble metal deposition) to increase life-time of carrier. Suitable band structure is responsible for the visible-light harvesting and effective separation of carrier of semiconductor photocatalyst.%作为一种新型的环境净化技术，半导体光催化技术已引起全世界范围的广泛关注。然而，传统光催化剂对太阳能利用率低、且光生电子–空穴对易于复合，极大限制了该技术的实际应用。因此，通过不同的改性手段合成具有可见光响应活性的光催化材料成为光催化领域研究的热点课题。提高光催化剂的活性，除了合成方法的优选(调控尺寸、形貌、结晶度、微结构)外，改性也是提高催化剂活性的主要手段。本文从半导体光催化的基本原理出发，概述了半导体光催化剂改性的基本思想：即拓宽太阳光利用范围和提高光生电子-空穴的寿命。围绕这一思想，常用的改性策略有化学结构调控(能带调控)，以拓宽光谱响应范围；表面修饰(表面敏化、半导体耦合和贵金属沉积)以提高电荷的分离效率。合适的能带结构是拓展催化剂的可见光响应范围和提高电荷分离效率的关键。