Carbon coated TiO2 nanoparticles prepared by pulsed laser ablation in liquid, gaseous and supercritical CO2.

We report on the synthesis of TiO₂ nanoparticles using nanosecond pulse laser ablation of titanium in liquid, gaseous and supercritical CO₂. The produced particles were observed to be mainly anatase-TiO₂ with some rutile-TiO₂. In addition, the particles were covered by a carbon layer. Raman and x-ray diffraction data suggested that the rutile content increases with CO₂ pressure. The nanoparticle size decreased and size distribution became narrower with the increase in CO₂ pressure and temperature, however the variation trend was different for CO₂ pressure compared to temperature. Pulsed laser ablation in pressurized CO₂ is demonstrated as a single step method for making anatase-TiO₂/carbon nanoparticles throughout the pressure and temperature ranges 5–40 MPa and 30 °C–50 °C, respectively. [ABSTRACT FROM AUTHOR]