Synthesis of nonstoichiometric titanium oxide nanoparticles using discharge in HCl solution

This study demonstrates the synthesis of nonstoichiometric titanium oxide (TiO2-delta) nanoparticles using plasma discharge. We have primarily investigated the effect of electrolyte concentration and edge shielding of electrode on the morphology, and oxygen defects of the final product. As a precursor for nanoparticle synthesis, titanium wire was utilized as a cathode, which was immersed in an HCl electrolyte in the concentration range of 0.1-5.0 M. The electrode edge was shielded to maintain uniform distribution of electric current. For comparison, we also used an electrode without edge shielding. Systematic studies indicate that the as-prepared products were spherical titanium oxide nanoparticles, the size of which decreased with decrease in electrolyte concentration. The edge shielding of the electrode was found to affect the size distribution and oxidation degree of the products. In case of the edge-shielded electrode, the oxidation of the product was suppressed, resulting in a product composition of TiO1.72. In contrast, in case of the electrode without edge shielding, the oxidation of the products was favored, resulting in formation of TiO1.90. This could be attributed to the concentration of electric current at the electrode edge, in which the heating-up of the electrode edge enhanced the oxidation of the product. These results confirm the possibility of synthesizing nonstoichiometric oxide nanoparticles with controllable oxygen defects by using plasma discharge in HCl solution. (C) 2014 AIP Publishing LLC.