Gas-Phase Fabrication and Photocatalytic Activity of TiO₂ and TiO₂-CuO Nanoparticulate Thin Films

CuO-loaded TiO₂ nanomaterials have applications in pollutant degradation via photocatalysis. However, the existing methods of fabricating these nanomaterials involve liquid-phase processes, which require several steps and typically generate liquid waste. In this study, TiO₂ and TiO₂-CuO nanoparticulate thin films were successfully fabricated through a one-step gas-phase approach involving a combination of plasma-enhanced chemical vapor deposition and physical vapor deposition. The resulting films consisted of small, spherical TiO₂ nanoparticles with observable CuO on the TiO₂ surface. Upon annealing in air, the TiO₂ nanoparticles were crystallized, and CuO was completely oxidized. The photocatalytic activity of TiO₂-CuO/H₂O₂, when introduced into the rhodamine 6G degradation system, was substantially enhanced under both ultraviolet and visible light irradiation. Moreover, this study highlights the influence of pH on the photocatalytic activity; TiO₂-CuO/H₂O₂ exhibited the highest photocatalytic activity at pH 13, with a reaction rate constant of 0.99 h^-1 cm^-2 after 180 min of visible light irradiation. These findings could facilitate the development of nanoparticulate thin films for enhanced pollutant degradation in wastewater treatment.