Photocatalytic degradation of gaseous acetaldehyde on TiO 2 with photodeposited metals and metal oxides

Abstract

The photocatalytic degradation of acetaldehyde by metal-photodeposited TiO 2 was analyzed at room temperature and elevated temperatures. In the humid condition, the acetaldehyde degradation rate of Pt–TiO 2 was larger than that of pure TiO 2, however, the degradation rate of Pd or Ag–TiO 2 was smaller. The degradation rate of metal-deposited TiO 2 depended on the oxidation state of metal, which also influenced the signal intensities of O 2 − and Ti 3+ in electron spin resonance (ESR) spectrum recorded at 77 K. By elevating temperature from 40 to 130 °C, the acetaldehyde degradation rate and the CO 2 production rate of Pt–TiO 2 were increased by the aid of metal Pt. Acetaldehyde is also thermocatalytically degraded by photodeposited Pt on TiO 2 at 70–190 °C without UV irradiation, however the UV irradiation is necessary for complete mineralization of acetaldehyde. The mineralization of acetaldehyde is considered to be enhanced by the partial oxidation of acetaldehyde by Pt thermocatalyst and the oxidation of intermediates into CO 2 by TiO 2 photocatalyst.