Urchin like CuO hollow microspheres for selective high response ethanol sensor application: Experimental and theoretical studies

Herein, the synthesis, characterizations and gas sensor application of nano-textured urchin like CuO hollow microspheres (HM) were reported. The detailed characterizations confirmed the uniform growth and nanocrystalline monoclinic structure of urchin like CuO HM. The synthesized urchins like CuO HM were utilized to fabricate resistive sensor devices which exhibited elevated response towards ethanol with high selectivity. The optimization of operating temperature was carried out for the highest ethanol response and the effect of different concentrations were also recorded. The sensor device showed 1241% response at an operating temperature of 225 °C for 100 ppm ethanol concentration. The lowest ethanol was detected at 25 ppm having the response of 49% by the fabricated CuO sensor device. Transient responses as well as stability of the sensor were analyzed. The selectivity of CuO sensor device was studied for NO₂, CO₂, CH₄ and H₂ gases and remarkably it was seen that the developed gas sensor devices demonstrated outstanding selectivity towards ethanol gas. Finally, the density functional theory (DFT) computational quantum modelling was utilized in order to understand the adsorption phenomenon of ethanol and oxygen molecules in the sensing application. An ethanol sensing mechanism using CuO sensor was also elucidated.