Simple Crystal Phase Control of TiO2 Nanoparticles via Pulsed Laser Ablation in Nitric Acid

摘要

It has long been known that anatase, brookite, and rutile are the major crystalline structures of TiO2, of which the rutile phase is the most stable; whereas anatase and brookite phases are metastable and easily transformed to the rutile phase by heating above about 600-800 °C.1 A number of investigations have been made on controlling the crystal structure and morphology of TiO2 using a variety of synthetic methods, such as by hydrolysis of Ti~(4+) ions, hydrolysis of titanium alkoxides or titanium tetrachloride4 in the gas phase, sol-gel, hydrothermal hydrolysis, and precipitation. Furthermore, a variety of attempts have been made to enhance the photocatalytic effects of TIO2, including metallic and non-metallic doping, nano-size reduction, and its use in bi-metallic catalysis.8 However, there is no report on the selective synthesis of the different phases of TiCh nanoparticles, involving different ratios of anatase and rutile, prepared in an ambient environment, i.e., through the variation of HNO3 concentration, without extreme temperature and pressure conditions.