【作者】 秦国辉；

【导师】 薛松；

【作者基本信息】 天津理工大学 ， 化学工程， 2012， 硕士

【摘要】 水体中存在有机污染物威胁着人类赖以生存的生态环境，很多持久性有机污染物能够致癌、致畸、致突变，对人类生存繁衍和可持续发展构成严重威胁。太阳能是一种清洁可再生能源，开发太阳能降解有机污染物对保护人类赖以生存的环境具有重要意义。本论文设计制备了类似染料敏化太阳能电池（DSSC）结构的光催化反应器，包括玻璃基体、纳米二氧化钛薄膜、染料敏化剂、电解液和对电极，与DSSC的不同之处在于：①TiO₂薄膜的载体用普通玻璃代替了DSSC中的导电玻璃；②TiO₂薄膜设置2个功能区，即敏化区和催化反应区。敏化区制备DSSC的夹层结构，催化反应区用于电子参与的化学反应。将光催化反应器和阳电极组成的光催化反应体系应用于可见光催化降解4-氯苯酚研究中，取得了良好的实验结果。在5小时的可见光照射（大于420nm）下，4-氯苯酚（4-CP）的去除率为87％；当外加电压为0.5V,经2小时的可见光照射, 4-氯苯酚的去除率就达到99％，表明在外加电压的作用下,对污染物的去除率显著增加。pH值的影响表明，酸性条件有利于活性氢氧自由基的形成，因而有利于提高降解效率。此外，还研究了无机盐、玻璃基体以及染料敏化面积等因素对降解效率的影响。利用香豆素与氢氧自由基易生成强荧光的7-羟基香豆素的特点，通过荧光光谱证实了光催化反应体系生成的氢氧自由基，讨论了4-CP的降解途径，提出了可能的降解机理。重复循环使用5次，表明所制备的双功能二氧化钛薄膜相当稳定。制备的光催化反应器具有特出优点，可以实现电子与正电荷的有效分离，使电子和正电荷分别在不同的溶液中均能产生氢氧自由基，都具有降解有机物的作用，显著提高了降解效率。将光催化反应器应用于光催化还原二氧化碳中，在pH=2，0.5 V外加电压下，光照3h后获得了0.315mmol/cm²的甲醇0.585mmol/cm²甲酸和0.621mmol/cm²甲醛。通过DSSC夹层中电解质完成电子与正电荷分离，电子在催化还原区将CO₂还原，而具有氧化性阳电极置于另一个容器里，避免了CO₂还原产物（如甲醇）被阳电极产生的·OH所氧化而消耗，提高了二氧化碳还原产物的浓度。此外对还原二氧化碳的机理也进行了研究。更多还原

【Abstract】 Organic pollutants in water threaten the ecological environment for human survival, manypersistent organic pollutants can cause cancer, teratogenic, mutagenic, posing a serious threatto human beings to survive and multiply, and sustainable development. Solar energy is a cleanrenewable energy, development of solar degradation of organic pollutants is of greatsignificance to the protection of human survival environment.This device is designed including the glass substrate, nano-titanium dioxide film, dyesensitivity agent , electrolyte and the electrodes, the difference to the DSSC is:①Thecarrier of the TiO₂ film of is ordinary glass instead of conductive glass in DSSC;②The TiO₂film contains two functional areas, the sensitized area and catalytic reaction zone. Sensitizedarea in preparation of DSSC is sandwiched structure, the catalytic reaction zone is forelectronic participation in chemical reactions.Photocatalytic reactor and the positive electrode composed of the photocatalytic reactionsystem is used for photocatalytic degradation of 4 - chlorophenol study in the visible light ,obtaining a good experimental results. After 5 hours of visible light irradiation （> 420nm）, 4 -chlorophenol （4-CP） removal efficiency reached 87% ,when a voltage of 0.5V applied,theremoval rate of 4 - chlorophenol was 99% after two hours of visible light irradiation,indicating if the applied voltage,a significant increase of the removal efficiency of pollutantscould be possible. The pH of the acidic conditions is favor to the formation of reactivehydroxyl radicals, and thus help to improve the degradation efficiency. In addition, inorganicsalts, glass substrate, and dye-sensitized area, and other factors on the degradation efficiencywere investigated. Coumarin hydroxyl radicals on formation of strongly fluorescent 7 -hydroxycoumarin characteristics were confirmed by fluorescence spectroscopy that thehydroxyl radicals generated by the photocatalytic reaction system.Possible degradationmechanism discussing the 4-CP degradation pathway was proposed. Repeating thedegradation five times showed that the bifunctionalized titanium dioxide thin films preparedwere fairly stable. The preparation of the photocatalytic reactor with outstanding advantagescan be achieved with the electronic and the positive charge of the effective separation ofelectrons and positive charge producing hydroxyl radicals in solution, respectively, have theadvantage of degradating organic compounds, significantly increased the degradationefficiency.The photocatalytic reactor was used in the photocatalytic reduction of carbon dioxide withthe condition （pH = 2,0.5 V applied voltage, for 3h visable light illumination） ,which gained 0.315mmol/cm²methanol 0.585mmol/cm²formic acid and 0.621mmol/cm²formaldehyde.Electronics and charge separation were achieved through the electrolyte in sandwiched DSSC,electrons participated in the catalytic reduction of CO₂, while the oxidizing anode is placed inanother container to avoid the oxidation and consumption of CO₂reduction products by thepositive electrode of.OH , increasing the concentration of carbon dioxide reduction products.In addition, the mechanism of reduction of carbon dioxide were also studied here.更多还原