Surface modification of nano-TiO2 with Cu nanoparticles

This study presents a practical and environmentally friendly approach for modifying TiO 2 with metallic copper (Cu) nanoparticles (NPs), using a low-temperature chemical process combined with ultrasonication, without the use of a reducing agent. The resulting Cu-modified TiO 2 photocatalysts were systematically characterised and tested for the degradation of Acid Orange 7 (AO7) and Rhodamine B (RhB). Diffuse reflectance spectroscopy (DRS UV–VIS) revealed a progressive narrowing of the band gap from 3.23 to 3.11 eV with increasing Cu content (0.5–5 wt%). Among the prepared samples, the material containing 0.5 wt% Cu exhibited the highest photocatalytic activity, achieving up to 99 % degradation of RhB and 98 % of AO7 under UV irradiation. The effects of irradiation sequence and duration were also evaluated. A three-step protocol, comprising 30 min of dark adsorption, followed by 30 min of UV (360 nm) or VIS (420 nm), and then 30 min of VIS (420 nm) or UV (360 nm) irradiation, was found to enhance degradation efficiency. Under combined irradiation conditions, RhB degradation reached 99 % for UV followed by VIS (UV + VIS) and 95 % for VIS followed by UV (VIS + UV), while AO7 showed a consistent degradation efficiency of 58 % for both irradiation sequences. This work demonstrates that even minimal Cu loading (0.5 wt%) can significantly enhance the photocatalytic performance of TiO 2 . The simple, low-cost synthesis method and strong photocatalytic response under UV and UV/VIS conditions highlight its potential for wastewater treatment and environmental remediation applications.