Cr-doped TiO2/CuO photocatalytic nanofilms prepared by magnetron sputtering for wastewater treatment

Photocatalytic processes are promising and ecofriendly approaches to degrade organic pollutants in water. However, the rapid bulk and surface recombination of photogenerated electron-hole (e-h) pairs is the main impediment to the application of photocatalysts. In this paper, TiO2/CuO nanofilms were fabricated and optimized by doping TiO2 with Cr via reaction magnetron sputtering. The morphology, crystalline phase, surface chemical composition, and optical features of the nanofilms were investigated via SEM, XRD, Raman spectroscopy, AFM, XPS, and UV–vis spectroscopy. The experimental results showed that Cr modification led to the production of TiO2 crystals with an increased surface area of the {0 0 1} facet and more surface oxygen vacancies (OVs). Cr-doped TiO2/CuO showed superior photocatalytic activity, degrading 94.1% of rhodamine B (RhB) over 120 min. Furthermore, the Cr-doped TiO2/CuO nanofilm maintained good photocatalytic performance after four cycles of photocatalytic degradation without obvious changes in the morphology or crystal structure. Capture experiments demonstrated that superoxide anion radicals were the main active substance, and a possible mechanism of the photodegradation reaction was proposed.