Photocatalytic colour enhancement of Methylene Blue and Rhodamine B dyes by coupled Titania Tenorite nanocomposites

Photocatalytic colour enhancement of Methylene Blue (MB) and Rhodamine B (RhB) dye is achieved by dual band gap Titania Tenorite (TiO₂/CuO) nanocomposite system prepared by a cost effective co-precipitation method. The UV-Visible and XPS analyses reveal that the existence of dual band gap is due to the coupling of the constituent metal oxides in the nanocomposite. The band gap of TiO₂ in the nanocomposite is tuned to the visible region, by changing the CuO content. Owing to the band gap tuning capability, the nanocomposite can be used from the UV to Visible region for the colour enhancement. The crystalline structure, morphology, molecular structure and chemical bonding of the samples are analyzed by XRD, FTIR and TEM. The PL spectrum shows a reduction in intensity with increase in CuO content. Methylene Blue and Rhodamine B dyes used to check the photocatalytic activity of TiO₂/CuO nanocomposite reveals that the dye-metal oxide nanocomposite forms an amazing combination providing a colour enhancement of dye in the presence of light due to the conversion of the dye from its colourless Leuco form to MB or RhB. The mechanism of colour enhancement is well justified by UV-Vis absorption spectra.