Modification Strategies for Semiconductor Photocatalyst Based on Energy Band Structure Theory

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. Besides 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.