摘要:
与植物光合作用相似,Z型光催化材料体系是由电子传输介质、光还原剂和光氧化剂组成的双光子体系,其应用于光催化反应具有很大的优势：借助双光子激发过程,在不同光催化剂上分别完成氧化反应和还原反应,有效促进了光生电荷的分离和迁移.Z型反应体系中的光催化剂只需分别满足各自的光激发过程和对应的半反应,为光催化材料的选择和设计提供了很大的空间.光催化还原位点和氧化位点分别在两个光催化半导体上,还原和氧化过程相互分离,可以有效抑制逆反应的发生.同时,催化材料光还原剂中的光生空穴被来自光氧化剂中的光生电子复合,光催化体系的稳定性随之增强.Z型光催化材料体系,表现出了宽光谱响应,高稳定性,高光生载流子的分离效率,强氧化还原能力,具有广阔的应用前景.
Abstract:
Z-type photocatlytic system, resembling natural photosynthesis, consists of two different photocatalysts and a shuttle redox mediator, involving two-photon excitation process for photocatlysis. One photocatalyst as a photoreduction system offers the reduction sites by conduction band (CB) electrons, and the other photocatalyst as a photooxidation system provides the oxidation sites by valence band (VB) holes. A shuttle redox mediator as an electron conductor transfers the electrons from the CB of the photooxidation system to the VB of the photoreduction system. On the one hand, the separation of photocatalytic reactive sites is advantageous for spatial separation of the electrons and holes, which is beneficial for enhancing the photocatlytic activities. On the other hand, photoreduction system and photooxidation system of different materials effectively inhibit the reverse reaction involvement of photoreductive and photooxidative products. The Z-type photocatlytic system simultaneously possesses a wide light absorption range and strong redox ability.
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