Photocatalytic Degradation of Gaseous Formaldehyde by Modified Hierarchical TiO2 Nanotubes at Room Temperature

Abstract

As a major indoor air pollutant, formaldehyde released from building and furnishing materials is one of the main volatile organic compounds (VOCs). Hierarchical TiO2 nanotube arrays (TiO2 NTs) prepared via a facile two-step anodization showed excellent photocatalytic (PC) degradation of formaldehyde at room temperature. Modification with noble metal nanoparticles (NMNs) could further improve the PC activity of TiO2 NTs. The final products of formaldehyde degradation were detected to be CO2 and H2O, which indicated that the mineralization of formaldehyde was the major process in this PC reaction. The reaction rate constants (k) determined for the three catalysts were in the order kTiO2 NTs < kAu/TiO2 NTs < kPt/TiO2 NTs (Pt/TiO2 NTs had the highest PC ability). The significant enhancement of PC performance can be ascribed to the formation of a Schottky junction between the NMNs and TiO2 NTs.