纳米TiO2阵列双室光电化学池分解水制氢耦合废水处理的研究

Hydrogen generation by photocatalytic water splitting using solar energy directly is one of effective routes to solve the problems of energy crisis and environmental pollution. The project proposes a new reaction system of photoelectrochemical generation of hydrogen, in which hydrogen generation by photocatalytic water splitting is simultaneous with degradation of organic pollutants driven by TiO2 nanotube arrays as photoanode and pH difference of electrolytes. The two-compartment photoelectrochemical (PEC) cell proposed in this study is separated by the proton-exchange membrane. Anodic and cathodic compartments are filled with acidic waste water and alkaline waste water, respectively. The pH difference between acidic electrolyte and alkaline electrolyte generates a chemical bias. Due to synergetic effect of chemical bias and the photovoltage of TiO2 generated under solar light illumination, hydrogen.generation in cathodic compartment and degradation of organic pollutants in anodic compartment can achieve without applying any external voltage in the two-compartment PEC cell. In this work, the reaction mechanism and the relationship between photocatalytic water splitting and degradation of organic pollutants has been investigated. Moreover, in order to improve the efficiency of photocatalytic hydrogen evolution and organnic pollutants degradation, TiO2 nanotubes have been modified by Ion dopping and semiconductor composite, which could reduce the recombination of photogenerated electron-hole pairs and extend the spectral response ranges to visible light. The research will provide scientific theoretical basis for hydrogen generation by photocatalytic water splitting and degradation of industrial waste water.

利用太阳能光催化分解水制氢是解决能源危机和环境污染问题的有效途径之一。本研究提出一个新型光电化学制氢反应体系，以TiO2纳米管阵列为光阳极耦合电解液pH差电位、驱动光催化分解水制氢和降解有机物；实现高效率、低能耗太阳能制氢。该体系采用质子交换膜(Nafion)将光电化学池分隔为阴极室和阳极室，分别采用酸性废水和碱性废水作为电解液，利用太阳光照TiO2产生的光电压协同双室电解液pH差产生的化学偏压，不施加外加电压，直接在阴极室还原制取氢气、在阳极室氧化降解有机污染物。本课题主要研究该体系的反应机制，揭示光解水制氢与有机污染物降解反应之间的协同作用及影响规律，同时通过对纳米TiO2进行离子掺杂、半导体复合等可降低光生电子-空穴的复合几率，并拓展其光谱响应范围至可见光，提高太阳能光电转换效率，为太阳能制氢及工业有机废水的同步降解处理提供新的思路和科学依据。

本研究构建了一个新型光电化学制氢反应体系，以TiO2纳米管阵列为光阳极耦合电解液pH差电位，采用质子交换膜(Nafion)将光电化学池分隔为阴极室和阳极室，分别采用酸性废水和碱性废水作为电解液，利用太阳光照TiO2产生的光电压协同双室电解液pH差产生的化学偏压，不施加外加电压，直接在阴极室还原制取氢气、在阳极室氧化降解有机污染物。本项目分别以钛片、钛粉、钛酸丁酯为钛源通过制备TiO2纳米管、纳米棒、纳米线，考察不同制备参数、煅烧温度对TiO2晶体结构、形貌的影响，以亚甲基蓝、罗丹明B染料为模拟有机污染物，考察材料合成参数、煅烧温度等对有机污染物降解率的内在影响规律。同时通过N掺杂、与能隙较窄的CdS半导体复合对TiO2纳米管进行改性，降低光生电子-空穴的复合几率，并将其光响应范围拓展至可见光部分，提高光电转换效率。本研究工作为解决能源危机和环境污染问题提供了新路径。