Tio <sub> 2 </ Sub> Thin Films And The Electric Field Assisted Light Catalysis Research

On the treatment of wastewater, photoelectrocatalytic method isbeing favored by more and more researchers for its effective, economicaland none secondary pollution. Mechanism of semiconductorphotoelectrocatalysis, research development of TiO₂ as well aselectrochemical impedance spectroscopy (EIS) were reviewed in thepaper. Aimed to investigate different effects to photoelectrocatalysis andfound connection between electrochemical impedance spectroscopy andsemiconductor photoelectrocatalysis, TiO₂ thin films and azocarminewere used.Titanium oxide thin films were deposited on Titanium net by directcurrent (D.C.) reactive magnetron sputtering and sol-gel method, andwere characterized by XRD. The photoelectrocatalystic system wasestablished to use the TiO₂ thin film as anode, Pt plate as cathode andstandard calomel electrode (SCE) as reference electrode. A25W UV lamp(254nm) was used as light source, azocarmine was used to simulatepolluted water, the photoelctrocatalytic oxidation reaction of printing anddyeing sewage was studied. The concentration of azocarmine wasdetermined by spectrophotometry, and the effects of some factors such aspreparation methods, anneal temperature, initial concentration, pH valueof solution, bias and reactive time were studied.The TiO₂ thin films which were annealed under 200℃wereamorphous. And TiO₂ thin films which were annealed under 500℃wereanatase, which had the capability of photoelectrocatalysis. A goodphotoelectrocatalysis property was investigated when an anodic bias wasapplied on the TiO₂ thin film, suggesting more efficient separation of thephoto-generated carriers. The rates of azocarmine degradation increasedwith the increase of anodic bias, pH value and the decrease of initialconcentration of azocarmine. But there exists the optimal conditions.These demonstrated the direction of wastewater treatment.At the same time, the electrochemical impedance spectroscopies ofthe photoelectrocatalystic system were studied qualitatively by CHI604Bpotentiostat. The EIS of the TiO₂ semiconductor photocatalyst thin film in the system were detected and analyzed under conditions of dark space,having UV light and different bias. Effects of the preparation methordsanneal temperature, initial concentration, pH value of solution, bias werediscussed based on the changes of EIS. The results were identical to theformer conclusions of the experiments of azocarmine degradation. Andthe connection between EIS and photoelectrocatalystic property wasestablished.