Characterization of metal ion-implanted titanium oxide photocatalysts operating under visible light irradiation.

Abstract

The metal ion-implantation of titanium oxide with metal ions (Cr + or V +) at high energy acceleration and the subsequent calcination of these metal ion-implanted TiO 2 in oxygen at around 725 K resulted in a large shift in the absorption spectra toward visible light regions. These catalysts exhibited effective and remarkable photocatalytic reactivity for various reactions such as the decomposition of NO into N2, 02 and N20 at 275 K not only under UV but also under visible light irradiation. XAFS, ESR and UV-Vis studies have revealed that the implanted metal ions (Cr + or V +) are located at the lattice positions of Ti 4+ in TiO2 and stabilized as Cr 3+ or (V 3+ or V 4+) species after the calcination of the sample in 0 2 at around 775 K. Thus, these spectroscopic studies show that the presence of these substitutional metal ion species are, in fact, responsible for the large shift in the absorption spectra of these catalysts toward visible light regions.