Titanium Dioxide Photocatalytic Degradation Of Organic Pollutants And Catalytic Reduction Of Carbon Dioxide

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.