Photocatalytic surfaces obtained through one-step thermal spraying of titanium

Abstract Advanced oxidation processes catalyzed by functional surfaces represent one of the most versatile methods for removing potentially toxic and persistent organic compounds from aqueous environments. This study is focused on obtaining two types of coatings with complex surface chemistry, involving titanium dioxide, nitrogen-doped titanium dioxide, titanium suboxides, and titanium nitride through a one-step thermal spraying method, starting from titanium feedstock powder. The differences in morphological and structural characteristics of coatings arise from the two different standoff distances between thermal spray nozzle and aluminum substrate (150 mm and 200 mm). The surface energies of the coatings range from 31 to 34 mN/m, which increase with up to 20% upon irradiation with UV light. The optical band gap values of the coatings are 2.01 eV and 1.55 eV respectively, indicating the possibility to harvest electromagnetic radiation from the visible domain in relation to photocatalysis applications. The photocatalytic activity of the surfaces has been tested against methylorange under UV (254 nm and 365 nm) and visible light irradiation. The photodegradation of methyl orange followed a pseudo-first order mechanism, with rate constants in the 0.0039–0.0871 min−1 interval. High photodegradation (91–99%) and dye mineralization (85–97%) efficiencies were registered for both types of coatings.