Kinetics of Dye Destruction Using Electrochemically Synthesized Sunlight Active N-Doped and C and N Co-Doped TiO2 Nanotubular Photocatalysts

Anatase phase N-doped and C and N-co-doped TiO2 nanotube powders were synthesized by a novel electrochemical technique, using urea as the precursor for carbon and nitrogen. The tubular morphology and crystal structure of the samples were confirmed from the results of scanning electron microscopy, transmission electron microscopy, X-ray diffraction and micro Raman spectroscopy. X-ray photoelectron spectroscopy of the N-doped samples revealed interstitial nitrogen doping and C and N co-doped samples revealed substitutional carbon and interstitial nitrogen co-doping. The band gap of 3.1 and 3.06 eV were obtained for N-doped and C and N co-doped nanotube powders respectively from diffuse reflectance spectroscopy. The photoluminescence spectrum revealed enhanced intensity, in the case of C and N co-doped TiO2, indicating higher density of defects. The photocatalytic activities of the N-doped and C and N co-doped TiO2 were investigated by analyzing the degradation kinetics of Rhodamine 6G (R6G) under sunlight at 34 degrees C and found to follow pseudo first order kinetics. The decolourization efficiency for N-doped and C and N co-doped samples was similar to 40% in 150 and 240 minute respectively. The lower efficiency of co-doped samples can be attributed to the higher density of defects, due to co-doping, which act as charge recombination centres.