Influence of Cu modified surface states by sol gel Technique on Photocatalytic Activity of Titanium dioxide

In a series of experiments for Cu doping in TiO2 in different precursor ratios and evaluation of MB degradation efficiencies, an interesting finding is observed in which dye degradation efficiency is reduced upon increasing Cu ratios. Cu doping in small ratios firstly increases the degradation efficiency but reduces this efficiency if Cu ratios increase to 2% and more. In the present report, we introduce sol gel technique for preparation and modified surface states of titanium dioxide by copper (Cu) doping in different precursor ratios of 2 w%, 4 w% and 6 w% respectively. The effect of introduced surface states on photo catalytic efficiency of as synthesized products was compared to pure TiO2 nanoparticles prepared with same technique. The crystal structure of the products was studied by XRD and Raman spectroscopy. Anatase and rutile phases of pure TiO2 and Cu doped samples were identified by XRD and the results were confirmed by analyzing Raman spectra of samples. The XRD and Raman spectroscopy results were in agreement. The presence of Cu peak at 43.6 degrees in all the doped samples suggest that surface states were introduced on titanium dioxide nano particle surfaces in the form of un-doped Cu. The morphological characterization for size distribution of samples was performed by FESEM as photo-catalytic activity strongly depends upon the size and shape of the catalyst. The elemental composition of the surfaces was estimated by EDAX which confirmed the presence of Cu and S on the surfaces of the Cu doped samples. The band broadening and band gap calculations were performed by optical characterization using PL and UV-vis spectroscopy results. The modified surface states were analyzed indirectly using results from PL and UV-vis techniques. Finally, the effect of these Cu modified surface states on photo-catalytic activity of as synthesized samples were studied by degradation of MB under visible light irradiation after specific intervals of time. The Langmuir-Hinshelwood (L-H) kinetic model (first order) was successfully applied on MB degradation results under irradiation by xenon lamp.