Influence of Anatase Content on the Photocatalytic Activity of Cold Gas Sprayed TiO2 coatings

GUTZMANN H.; KLIEMANN J.-O.; GAERTNER F.; KLASSEN T.; TOMA F.-L.; BERGER L.-M.; LEUPOLT B.; STOETZNER J.; MENDIVE C.; BAHNEMANN D.

Seoul

Conferencia; 18th International Conference on Photochemical Conversion and Storage of Solar Energy; 2010

A novel coating technique called cold gas spraying [1] was used to study the influence of nanocrystalline rutile/anatase content on the photocatalytic activity of the coatings. Cold gas spraying allows producing durable TiO2-coatings in a way that the microstructure and the phase content of the particles is retained. There is no binding agent necessary for the coating, since the particles are bound solely by their kinetic energy. This leads to a direct metal-semiconductor bonding on the surface of the substrate. The powder feedstock comprised of a) pure anatase powder, b) pure rutile powder and c) mixtures of both a) and b). The cold-sprayed coatings are compared to coatings obtained by using different, conventional high-temperature spray techniques: atmospheric plasma spraying, high velocity oxy-fuel spraying and suspension high velocity oxy-fuel-spraying. During these processes, high temperatures trigger a partial phase transition of anatase to rutile, which was quantified by X-ray diffraction. The photocatalytical activity was measured by dichloroacetic acid (DCA) degradation in the liquid phase and nitric oxide oxidation and acetaldehyde decomposition in the gas phase. The results show that the photocatalytic activity correlates with the anatase content of the coatings and the substrate material.