Highly reactive photocatalytic TiO2 layers produced by cold gas spraying

KLIEMANN J.-O.; GUTZMANN H.; GAERTNER F.; KLASSEN T.; STOETZNER J.; DILLERT D.; MENDIVE C.; BAHNEMANN D.

Conferencia; Third International Conference on Semiconductor Photochemistry (SP-3); 2010

A novel technique, cold spraying, was used to produce anatase titanium dioxide coatings on different metal surfaces exhibiting very high photocatalytic activity. In cold spraying, anatase particles are accelerated in a gas stream to velocities of more than 800 m/s and bind to the substrate solely by their kinetic energy. Binder agents are not required. No phase transition from anatase to rutile could be observed and TEM micrographs show that the nanocrystalline microstructure is retained. The initially present secondary structure of the TiO2 nanoparticles bursts on impact leaving behind the primary nanocrystals and resulting in a large surface area (Figure 1). Photocatalytic activities comparable to the feedstock powder are achieved employing the oxidation of nitric oxide in the gas phase as test reaction (Figure 2). First wear tests indicate a higher durability of cold sprayed TiO2 coatings as compared to sol-gel-processed samples. Therefore, cold sprayed titanium dioxide coatings will have an excellent application potential for water and air purification due to their high photocatalytic activity and their durability.