Cold gas dynamic spraying (CGDS) of TiO2 (anatase) powders onto poly(sulfone) substrates: Microstructural characterisation and photocatalytic efficiency

Thin TiO2 coatings were deposited by cold gas dynamic spraying (CGDS) on different types of thermoplastic poly(sulfone) material using nitrogen as process gas and commercially available TiO2 (anatase) powder as feedstock. The properties of the coatings were investigated as functions of gas temperature and pressure. Coating microstructure and phase composition were characterised by scanning electron microscopy and micro-Raman spectroscopy, respectively. The photocatalytic efficiency of the coatings was monitored through the decomposition of 4-chlorophenol in aqueous solution, and the initial reaction rates, i.e. rates of pH decrease compared to those of standard Degussa P-25 coatings. It was found that most CGDS coatings showed excellent adhesion to the substrate and suitable surface roughness as well as photocatalytic activities equal to or higher than those of the reference coating.