Growth of Rutile Titanium Dioxide Nanowires by Pulsed Chemical Vapor Deposition

Recently, we developed a surface reaction-limited pulsed chemical vapor deposition (CVD) technique that can grow highly uniform anatase TiO2 nanorods (NRs) over a large area, even inside highly confined submicrometer-sized spaces. Here, we report the growth of rutile TiO2 NWs using this technique by introducing a Au seeding layer at higher deposition temperature, where a small amount of anatase phase was also found. A bifurcated growth of rutile TiO2 NWs was observed. The resulting TiO2 NWs exhibited high-quality crystallinity and large surface areas with exposure of high-index surfaces. Control experiments illustrated the influence of deposition conditions on the TiO2 growth behavior. Higher deposition temperature could convert the TiO2 phase from anatase to rutile. A thin film of Au was able to induce rapid crystal growth resulting in particle formation, while the anisotropic NW growth preferred no Au coating. Shorter purging time could significantly enhance the deposition rate because of the incomplete removal of precursor molecules. This research enriched our knowledge of the surface reaction-limited pulsed CVD technique and demonstrated the capability of using this technique to control the TiO2 phase and morphology.