Preparation and VOC gas sensing properties of Sr(II)-added copper aluminate spinel composites

Pure and strontium(II)-added CuAl2O4 composites prepared by sol–gel technology were investigated for their sensing properties towards volatile organic compounds (VOCs) like benzene, toluene, hexane, heptane and acetic acid. X-ray diffraction, scanning electron microscopy (SEM) and nitrogen adsorption/desorption isotherms at 77 K were employed to identify the structural phases, surface morphology and BET surface area of the composites, respectively. The results revealed that the sensitivity factor increased with an increase in temperature up to the optimum temperature at which the maximum sensitivity was obtained and thereafter progressively decreased. Among all the composites tested, CuSA5 (the Cu:Sr molar ratio was kept as 0.2:0.8) showed the highest sensitivity to all VOCs under investigation. The sensitivity factor (Sf) data in the studied temperature range for all the vapors were employed to fit the Gaussian function. The fit parameters revealed that the data satisfactorily fitted for hexane and acetic acid vapors than the other vapors taken for the study.