Co-sensitization in the Visible Light/H2O2 System

The causes of co-sensitization in the visible light/H2O2 system was analyzed. Through the analysis of the UV-Vis spectra of the phenol red, methyl orange, azure I and the mixed solution which consisted of all the three solutions mentioned above , it was seen that the mixed solution broadened the response range in the visible light region so that the utilization rate of visible light was increased. The yields of photoinduced electron ( hydrated electron) , singlet oxygen and superoxide anion radical generated under visible light in these matters mentioned above were tested by 1, 10-phenanthroline method , 1, 5-diphenylcarbazide method and ammonium molybdophosphate spectrophotometry. The result showed that the yields of superoxide anion radical in the mixed solution was significantly higher than that of the single chromophoric dissolved organic matters , moreover, the yields of photoinduced electron and singlet oxygen were not much different in each solution. Hence the increase of superoxide anion radical production is the main reason for the co-sensitization. In addition, experimental results confirmed that photoinduced electron could not catalyze hydrogen peroxide to generate hydroxyl radical.