Effect of various fuels on structure and photo-catalytic activity of TiO2 nano-crystalline prepared by microwave-assisted combustion method

Nano-crystalline TiO2 were synthesized by combustion method using metal nitrate solution and urea, glycin and citric acid fuels. Microwave irradiation was used as heating source. X-ray diffraction, scanning electron microscope as well as Fourier transform infrared spectroscopy were performed to characterize the obtained samples. X-ray diffraction patterns revealed that in the case of citric acid a calcination step was needed to obtain the desired phases. Moreover, the ratio of rutile/anatase phases varied from 25/75 to 0/100 as the fuel type changes from urea to glycine and citric acid. The crystallite size of the as-synthesized samples calculated by Scherer formula was 8-15 nm. From scanning microscopy images thick and thin flaky particles were detected for citric acid and urea samples and porous spongy morphology for glycine sample. Due to a well-crystallized mixed crystalline structure 75 anatase - 25 rutile, the urea sample seemed to be a better candidate for photo-catalytic functions.