Preparation of gas sensing CoTiO3 nanocrystallites using EDTA as the chelating agent in a sol–gel process

Abstract

CoTiO3 nanocrystallites with an average diameter of 40nm were prepared by the sol–gel method using C10H16N2O8 (EDTA) as the chelating agent. The thermal decomposition process and chemical bonding of the precursor were studied by thermogravimetric-differential scanning calorimetry and fourier transform infrared spectra, respectively. The as-prepared nanocrystallites were characterized by X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy. The effects of calcination temperature, sol pH and chelating agent on the formation of CoTiO3 were investigated. The results show that calcination temperature is a key factor controlling the composition of the products. Acid sol is the optimum condition for hydrolysis and polycondensation of Ti(OC4H9)4. Co2+ and Ti4+ were bonded together by EDTA, and pure CoTiO3 nanocrystallites were obtained due to this chelating effect. The chelating mechanism and the formation process of CoTiO3 in the sol–gel process were proposed. Furthermore, the nano-CoTiO3 was applied to make a gas sensor, and the response value to 104ppm ethanol was 17.9, response time and the recovery time were 13s and 10s, respectively.