Detection of H₂O₂ Released from TiO₂ Photocatalyst to Air

Abstract

H₂O₂ generated and released from TiO₂ photocatalysts to the gas phase was detected. A flow-through cell packed with TiO₂-coated glass beads was irradiated with UV light, and the gas flowing out of the cell was flushed through a collecting solution containing 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulforic acid) diammonium salt (ABTS) and peroxidase. Oxidative coloration of ABTS was observed only in the absence of catalase, indicating the presence of H₂O₂ in the gas. The quantum yield of the H₂O₂ generation was estimated to be >1 × 10^-7. The detected amount of H₂O₂ decreased as the TiO₂ thickness decreased. H₂O₂ was not detected when dry air or nitrogen was used.