Green synthesis of tin oxide based nanoparticles using Terminalia bellirica seed extract: impact of operating temperature and antimony dopant on sensitivity for carbon dioxide gas sensing application

Green synthesis of undoped tin oxide (SnO2) and 2 wt% antimony doped tin oxide (Sb:SnO2) for carbon dioxide (CO2) gas sensing application is reported. The structural, morphological and optical properties of nanoparticles were investigated using XRD, SEM, EDX, HRTEM, FTIR and UV-Vis characterisation techniques. CO2 gas sensing studies were carried out by using calibration setup on pellets of nanoparticles. From XRD, SEM and HRTEM analysis, the average size of Sb:SnO2 nanoparticles were found decreased than the SnO2 nanoparticles. EDX analysis indicated the presence of tin, antimony and oxygen elements in the structure of nanoparticles. The presence of functional groups responsible for the formation of nanoparticles was identified by FTIR spectra. Bandgap of SnO2 and Sb:SnO2 nanoparticles was found to be 3.67 eV and 3.47 eV respectively. The sensitivity of SnO2 and Sb:SnO2 nanoparticles at the optimized operating temperature was found as 18.32% and 35% at 1000 ppm CO2 gas concentration.