Studies On The Action Of TiO₂Photo-induced Electrons

Hydroxyl free radical can be found in traditional TiO₂photocatalysis, but there is no finalconclusion about the relation between hydroxyl free radical and photo-induced electron–holepairs. Photoelectrocatalytic method has been used in this paper. Photo-induced electrons andholes were effectively separated by a bias-voltage between two electrodes. Holes which wereleft at TiO₂anode had been studied fully, but there was a lack of research to photo-inducedelectrons which were transferred to TiO₂cathode. Therefore, the degradation of pollutants andthe reaction mechanism of photo-induced electrons were chosen as research focus in this paper.This paper included:1. P-benzoquinone was used as a target pollutant to study reactions of photo-inducedelectrons. When the solution pH was5.2, oxygen aeration in the cathode chamber, constantcurrent value was3.5mA, cathode material was TiO₂/Ti electrode fired by600℃, a cationexchange membrane, the optimal degradation of p-benzoquinone was78.7%in the cathodechamber.2. Cyclic square wave voltammetry was used to analyse the TiO₂/Ti microelectrode undernegative potential. The experiment results showed that H+and O₂participated in the chemicalreaction of TiO₂/Ti cathode.3. An improved method for determination of trace hydrogen peroxide in water had beenused. Hydrogen peroxide was determined in the photoelectrocatalytic system cathodechamber.4. Hydroxyl free radical production （2,3-dihydroxy benzoic acid and2,5-dihydroxybenzoic acid） in the photoelectrocatalytic system cathode chamber was determined by aspectrophotometric method using salicylic acid as the molecular probe, it was indirectlydemonstrated that hydroxyl free radical was a reaction product of photo-induced electrons.Depending on all above studies and experiments, it was demonstrated that hydroxyl freeradical can be produced by chemical reactions of photo-induced electrons, O₂and H+.