| Abstract
| - To characterize the formation of H2O2 in photocatalytic reactions, HCHO and HCOOH have beenphotocatalytically decomposed by use of TiO2 and Pd/TiO2 under irradiation with the UV light emitted froma blacklight blue fluorescent lamp (BL) or germicidal lamp (GL). An enzymatic method has been introducedto accurately measure the H2O2 concentration. The photocatalyst irradiated with the UV light emitted fromthe GL produces H2O2 from water at a larger rate and amount. Deposition of Pd on TiO2 increases the rateand amount of the formation of H2O2 from water. In the absence of the photocatalyst, no HCOOH isdecomposed under irradiations with both the UV lights from the BL and GL, whereas the decompositionbecomes possible in the presence of the photocatalyst. H2O2 is formed in parallel with the photocatalyticdecomposition of HCOOH. In the presence of the photocatalyst, the concentration of the H2O2 formed duringthe decomposition of HCHO is smaller than that formed from water alone. In contrast, this relationship isreversed with the decomposition of HCOOH. This is considered due to the formation of H2O2 in the processof the decomposition of HCOOH to carbon dioxide and water. The rates of decomposition of HCHO andHCOOH are directly proportional to their respective rates of formation of H2O2, indicating that there is aclose relationship between the photocatalytic activity and the capability of the photocatalyst to form H2O2.
|
