Post-Plasma SiOxCoatings of Metal and Metal Oxide Nanoparticles for Enhanced Thermal Stability and Tunable Photoactivity Applications.
The plasma-based aerosol process developed for the direct coating of particles in gases with silicon oxide in a continuous chemical vapor deposition (CVD) process is presented. It is shown that non-thermal plasma filaments induced in a dielectric barrier discharge (DBD) at atmospheric pressure trigger post-DBD gas phase reactions. DBD operating conditions are first scanned to produce ozone and dinitrogen pentoxide. In the selected conditions, these plasma species react with gaseous tetraethyl orthosilicate (TEOS) precursor downstream of the DBD. The gaseous intermediates then condense on the surface of nanoparticles and self-reactions lead to homogeneous solid SiOxcoatings, with thickness from nanometer to micrometer. This confirms the interest of post-DBD injection of the organo-silicon precursor to achieve stable production of actives species with subsequent controlled thickness of SiOxcoatings. SiOxcoatings of spherical and agglomerated metal and metal oxide nanoparticles (Pt, CuO, TiO₂) are achieved. In the selected DBD operating conditions, the thickness of homogeneous nanometer sized coatings of spherical nanoparticles depends on the reaction duration and on the precursor concentration. For agglomerates, operating conditions can be tuned to cover preferentially the interparticle contact zones between primary particles, shifting the sintering of platinum agglomerates to much higher temperatures than the usual sintering temperature. Potential applications for enhanced thermal stability and tunable photoactivity of coated agglomerates are presented.
Institute of Particle Technology, Clausthal University of Technology, Leibnizstrasse 19, 38678 Clausthal-Zellerfeld, Germany. patrick.post@tu-clausthal.de.
Patrick
P
Post
Lab of Phys Gaz and Plasmas, CNRS, Univ. Paris Sud, CentraleSupelec, Université Paris-Saclay, F-91405 Orsay, France. nicolas.jidenko@u-psud.fr.
Nicolas
N
Jidenko
Institute of Particle Technology, Clausthal University of Technology, Leibnizstrasse 19, 38678 Clausthal-Zellerfeld, Germany. weber@mvt.tu-clausthal.de.
Alfred P
AP
Weber
Lab of Phys Gaz and Plasmas, CNRS, Univ. Paris Sud, CentraleSupelec, Université Paris-Saclay, F-91405 Orsay, France. jean-pascal.borra@u-psud.fr.
Jean-Pascal
JP
Borra
CVD; TEOS; continuous process; dielectric barrier discharge; gas phase; particle coating; silicon oxide