Photocatalytic removal of airborne indoor pollutants by IR illuminated silver coated TiO2 catalyst: Advantage of one-dimensional TiO2 nanostructures in IR active photocatalysis

Abstract

The development of IR sensitive photocatalysts is indispensable for the abatement of indoor pollutants as most of the photocatalysts mainly absorb radiation in the UV region and weakly in the visible region and not responding to indoor conditions. On the other hand, IR photons initiated photochemical reaction needs a highly efficient excited charge separation step as it is a multi-excitation process. In order to enhance the charge separation process in multi-step excitation photocatalytic systems, in this investigation the photocatalytic activities of silver coated 1-D TiO2 nanotubes were employed and the photocatalytic activity of 1-D TiO2nanotubes was compared with the photocatalytic activity of TiO2 nanoparticles. A superior photocatalytic activity was noted with the silver coated 1-D TiO2 nanotubes under IR irradiations than that of silver coated TiO2 nanoparticles. The impedance measurements were conducted by electrochemical impedance spectroscopy to differentiate the transport resistances, electron-hole recombination and electron lifetime of the silver coated 1-D TiO2nanotubes and nanoparticles. The possibility of the use of silver coated 1-D TiO2 nanotubes for the degradation of common airborne pollutants with near IR photons (similar to indoor conditions) was successfully demonstrated.