Surface Modification of Rutile TiO<SUB>2</SUB> by Submerged Arc Discharge for Improved Photoreactivity

Abstract

Titanium dioxide is well known for its photocatalytic activity, but it works effectively only in the ultraviolet (UV) range. Given the relatively low flux of solar UV that reaches earth, the potential of exploring its photocatalytic capacity for environmental protection applications is very limited. In this study, rutile, the least photocatalytic of the three existing titanium dioxide crystalline forms, was suspended in water or acetonitrile and treated with oxygen or argon plasmas, using a novel dense-medium plasma technology (submerged arc discharge). As a result of the plasma treatment, rutile particles were doped with various trace elements that originated in electrodes made of different metals. Subsequent analyses show that the photocatalytic capacity of plasma-modified rutile is comparable to or even better than that of unmodified anatase, the most photocatalytic form of titanium dioxides. The color change of TiO2 samples after plasma treatment indicates that the modified rutile absorbs visible light and may therefore work as a photocatalyst in the visible range. Given the fact that rutile can be produced in large quantity more easily and cheaply than can anatase, these results are very encouraging and open up possibilities in using rutile for photocatalytic applications in the visible range.