A simple process for synthesizing nano Pt- and/or N-doped titanium dioxide powders by microwave plasma torch

Abstract Simultaneous N- and Pt-doped TiO 2 powders are usually synthesized via multi-stage processes. In this study, Pt/N-doped (sample Pt/N-TiO 2 ), Pt-doped (sample Pt-TiO 2 ), N-doped (sample N-TiO 2 ), and without doping (sample TiO 2 ) TiO 2 in the form of spherical nano to micro-particles are rapidly synthesized in a single-step process by spraying clear Ti- and Pt-containing nano aerosols into an atmospheric-pressure microwave plasma torch. The anatase modified Pt/N-TiO 2 powders were produced in about 0.12 s. After the collection of 14-stage impactors, the size distribution showed that the most of the particles by number were in the 2 , Pt-TiO 2 , and Pt/N-TiO 2 powders, respectively, although the mass distribution of the powders was mainly in the 1–2.5 μm range. Chemical composition analysis showed that the N doped contents were 0.47, 0.21, and 0.41 at.% in the N-TiO 2 , Pt-TiO 2 , and Pt/N-TiO 2 powders, respectively, levels higher than that of the TiO 2 sample (0.12 at.%). As a result, the photocatalytic activities of N-containing (N-TiO 2 and Pt/N-TiO 2 samples) powders are significantly higher than those of TiO 2 and P25 under visible light degradation. The rapid production of N- and/or Pt-TiO 2 powders by using a simple plasma process can thus be achieved successfully for use in photocatalytic applications.