Photocatalytic performance of copper-based coatings deposited by thermal spraying

Visible light-activated photocatalysts are gaining general importance in advanced methods for removing persistent organic compounds. In this study, two types of composite oxide-metal coatings are obtained on copper substrates through thermal spraying of an aluminum bronze powder with different time-of-flight distances between the spraying nozzle and the substrate (150 and 200 mm). The surfaces of the coatings consist of nanopatterned α-Fe₂O₃ and Cu_xO produced by oxidation of the metal phase during the thermal spraying process. The optical band gap energies of the coating assemblies are 2.573 and 2.131 eV, respectively, and the Brunauer–Emmett–Teller (BET) specific surface areas are 4.65 and 4.87 m² g⁻¹, respectively. The photocatalytic performance of the two types of thermally sprayed coatings in the visible region is studied using methylene blue as a model compound. The coatings present remarkable stability in aqueous environments, good hydrophilicity, high photodegradation rates (0.20–0.26 h⁻¹), high organic dye mineralization efficiencies (75.69 and 92.36%) and unaltered methylene blue removal efficiencies during three successive 12 h photodegradation cycles (91–99.60%).