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光催化分解水制氢被认为是解决能源问题和环境问题的有效方法,但目前的光催化效率仍然较低,结合使用2种半导体物质是提高光催化活性的一种有效途径。本文分两种类型阐述了已报道的用于光催化分解水制氢反应的二元半导体体系。一种为将2种半导体复合于一体,另一种为将2种半导体分散加入到光催化反应液中的Z型体系。基于肖特基模型探讨了2种半导体复合于一体的二元体系的光催化作用机制,指出p型半导体和n型半导体复合制得的光催化剂更能很好地发挥各半导体的光催化氧化性能和光催化还原性能。分析了Z型体系的优点和缺点,指出对于Z型体系的放氢催化剂和放氧催化剂也可以分别再进行二元复合改性,以抑制光激发载流子的复合,提高整个体系的光催化效率。
Photocatalytic decomposition of water to hydrogen is considered as an effective way to solve the energy and environmental problems. However, the current photocatalytic efficiency is still low. The combination of two kinds of semiconductor materials is an effective way to improve the photocatalytic activity. In this paper, two types of binary systems have been reported for photocatalytic decomposition of water to produce hydrogen. One is a Z-type system in which two types of semiconductors are combined together, and the other type is a dispersion in which two types of semiconductors are dispersed in a photocatalytic reaction liquid. Based on the Schottky model, the photocatalytic mechanism of two kinds of semiconductor composites in binary system was discussed. It is pointed out that photocatalysts prepared by the combination of p-type and n-type semiconductors can better exert the photocatalytic oxidation performance of each semiconductor And photocatalytic reduction performance. The advantages and disadvantages of the Z-type system are analyzed. It is pointed out that binary recombination can be carried out for the hydrogen-releasing catalyst and the oxygen-releasing catalyst in the Z-type system respectively to suppress the recombination of photoexcited carriers and improve the photocatalytic activity of the whole system effectiveness.