Effect of Various Fuels on Structure and Photo-Catalytic Activity of Nano-‎Crystalline TiO2 Prepared by Microwave-Assisted Combustion Method

Nano-crystalline TiO2 powders were ‎synthesized by combustion method ‎using metal nitrate solution and ‎urea, glycine and citric acid fuels. ‎Microwave irradiation was used as ‎the heating source. X-ray ‎diffraction, Scanning‏ ‏Electron ‎Microscopy, Fourier Transform ‎Infrared Spectroscopy and ‎Brunauer-Emmett-Teller surface ‎area analysis were performed to ‎characterize the prepared samples. ‎X-ray diffraction patterns revealed ‎that in the case of citric acid, ‎calcination step is needed to ‎obtain the desired phase. ‎Moreover, the ratio of ‎rutile/anatase phases varied from ‎‎25/75 to 0/100 as the fuel type was ‎changed from urea to glycine and ‎citric acid. The crystallite size of ‎the synthesized samples was ‎calculated by Scherrer’s formula ‎which was revealed to be 8-15 nm. ‎The highest surface area was ‎observed when glycine fuel had ‎been used. By Scanning ‎Microscopy images, thick and thin ‎flaky particles were detected in ‎the case of citric acid and urea ‎samples while a porous spongy ‎morphology was seen when using ‎glycine sample. The sample ‎synthesized using urea is a better ‎candidate for photo-catalytic ‎functions due to a well-crystallized ‎mixed crystalline structure (75% ‎anatase - 25% rutile) which results ‎in the synergistic effects of mixed ‎anatase and rutile phases‎