Influence of the oxygen concentration on the formation of crystalline phases of TiO$_2$ during the low-pressure arc-discharge plasma synthesis

The synthesis of titanium dioxide (TiO$_2$) nanoparticles with different percentage of anatase and rutile phases is investigated. The synthesis is performed by controlling the oxygen percentage in the gas mixture in the plasmachemical evaporation–condensation process employing a low-pressure arc discharge. In all our experiments, the pressure in the plasmachemical reactor and the average size of particles remain constant and are 60 Pa and 6 nm, respectively. The crystal structure of synthesized TiO$_2$ is studied using X-ray diffraction; the morphology of the particles is analyzed employing transmission electron microscopy. Using X-ray phase analysis, it is established that the concentration of the TiO$_2$ anatase phase decreases upon a decrease in the oxygen concentration in the gas mixture. It is shown that the TiO$_2$ anatase phase is more efficient for photocatalytic decomposition of methylene blue than the rutile phase.