活性艳红和分解水制氢的机理
(1. 黄冈师范学院 物理科学与技术学院，黄冈 438000；2. 华中师范大学 纳米科技研究院，武汉430079)
摘 要: 采用溶胶−凝胶法和化学沉积法制备纳米TiO2/Cu2O复合粉体。可见光光催化实验结果表明：TiO2/Cu2O复合粉体具有较高的可见光降解活性和分解水制氢性能。根据TiO2和Cu2O的导带和价带位置以及TiO2、Cu2O和TiO2/Cu2O复合粉体的可见光光催化实验结果，提出TiO2/Cu2O复合粉体的可见光光催化机理：在可见光照射下，Cu2O导带上产生的电子转移到TiO2的导带上，Ti4+捕获这些电子后成为Ti3+，这些被捕获的电子具有很长的寿命，能转移到复合粉体和溶液的界面。在光降解活性艳红的过程中，这些电子与吸附氧结合后可最终形成过氧化物自由基或氢氧自由基，从而氧化有机物；而在分解水制氢过程中，这些电子与H+结合后可形成H2。光照后TiO2/Cu2O复合粉体的XPS表征显示Ti3+的存在，证明机理理论的正确性。
关键字: TiO2/Cu2O复合粉体；活性艳红；三价钛离子；光催化；制氢；X射线光电子能谱
（1. Physics Department, Huanggang Normal University, Huanggang 438000, China;
2. Institute of Nanoscience and Nanotechnology, Huazhong Normal University, Wuhan 430079, China）
Abstract:TiO2/Cu2O composites were prepared by a simple sol-gel process and chemical deposition method. The results of photocatalytic experiments under visible light irradiation demonstrate that the TiO2/Cu2O composite has the ability of degrading brilliant red X-3B and producing H2 from water. The mechanism of photocatalytic reaction under visible light is proposed based on band theory and the experimental results. The electrons excited from TiO2/Cu2O composite under visible light are transferred from the conduction band of Cu2O to that of TiO2. These electrons from Cu2O are then captured by Ti4+, which afterward are changed into Ti3+. These electrons located in Ti3+ in the conduction band of TiO2 have a long lifetime. They can be transferred to the interface of composite and solution. In the experiment for photodegradation of brilliant red X-3B, these electrons can be captured by the O2 adsorbed on the interface to form HO2· or ·OH, which can oxide organic compounds. In the process of H2 evolution, these electrons can directly combine with H+ to form H2. XPS spectra are also carried out and provide evidence for the proposed mechanism.
Key words: TiO2/Cu2O composite; brilliant red; Ti3+ ions; photocatalysis; hydrogen production; X-ray photoelectron spectrum
