Characterization Of Photo-electrocatalyst Properties Of TiO₂ By AC Impedance Method

According to a great deal of papers on TiO2 photoeletrocatalysis of waster water degradation, three vital problems which limited the industrialization of photoelectrocatalysic process were put forward in this paper, and some defects on the current characterization of photo-catalyst were also put forward.Aimed at solving the problems, the semiconductor heterogeneous photocatalystic system was studied by the AC Impedance method. The AC Impedance spectra of the TiO2 semiconductor-photocatalyst in the system was detected and analyzed by a Potentiostat(M273A) and a Frequency Spores Detector (M1025) with its relevant powersine software under conditions of having no lights , light with various wavelengths and changed anodic bias, moreover studied the influence of the wavelength , bias and light intensity on the photo-catalysis in the photoelectrocatalysic process of phenol on the aspect of changes of impedance. The results of the following experiments of phenol degradation were identical to the former conclusions.The AC Impedance data were dealt with by the way of Equivalent Circuit. Two kinds of equivalent circuit models of TiO2 semiconductor-electrode system were put forward, which Model I CDC code is R(RC)(RQ) and Model II CDC code is R(R[CQ]), respectively . Herecompared with plenty of simulated results of different experiments, Model I was thought to be the better one. In addition, by using the EquiVcrt software to analyze and simulate the EIS, we calculated these parameters of semiconductor Energy-band Structure and set up a new way of AC Impedance Spectra to characterize the TiO2 photo-catalyst. Factors influencing the activity of semiconductor catalyst were found so as to improve TiO2 photo-catalyst activity.