Preparation of visible-light-responsive TiO2 coatings using molten KNO3 treatment and their photocatalytic activity

Abstract In this work, the process of mechanical coating followed by molten KNO 3 treatment is given to prepare visible-light-responsive K + -doped TiO 2 . X-ray diffraction (XRD), scanning electron spectroscopy (SEM), Energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS) were conducted to characterize these TiO 2 coatings. The results showed that K + -doped anatase TiO 2 /Ti composite coatings formed after molten KNO 3 treatment at elevated temperatures. Meanwhile, their photocatalytic degradation of methylene blue (MB) and the antibacterial activity against Escherichia coli ( E. coli ) was also studied. The visible-light-responsive photocatalytic activity of the coatings in MB degradation increased with increase of K + ions when holding temperature was raised from 673 to 773 K. An excellent antibacterial activity of the K + -doped TiO 2 /Ti coatings against E. coli was also obtained even in absence of light. The antibacterial activity in dark should attribute to the release of K + ions from the coatings. The photocatalytic activity under visible-light irradiation should result from the absorption spectrum extension due to the doping of K + ions into the lattice of TiO 2 .