Low temperature synthesis of rutile TiO₂ nanocrystals and their photovoltaic and photocatalytic properties

We report a novel method of synthesizing rutile TiO₂ nanocrystals at low temperature (200 ° C) via a butanol rinsing process followed by heat treatment in an O₂ atmosphere. The rutile nanocrystals show uniform size distribution of approximately 20 nm and good crystallinity confirmed by X-ray diffraction and transmission electron microscopy. A mechanism for the low temperature synthesis of rutile nanocrystals is rationalized in terms of an explosive thermal decomposition reaction of butoxy groups on TiO₂ powders with O₂ gas. Characterizations of the photovoltaic and photocatalytic properties of rutile nanocrystals exhibited higher photoactivity than large-sized conventional rutile powder, which demonstrates that this novel synthesis technology could expand applications of rutile powders to various photoactive devices beyond solar cells and photocatalysts.