Effect of Er doping on flame-made SnO2 nanoparticles to ethylene oxide sensing

Abstract In this research, 0.05–2 wt% Erbium (Er)-doped SnO2 nanoparticles were synthesized for the first time by flame spray pyrolysis and their gas-sensing properties were methodically characterized. The structural analyses based on scanning/transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen sorption analysis, and photoluminescent spectroscopy suggested that nanocrystalline SnO2 nanoparticles were substitutionally doped with Er+3 species. The sensing films were prepared by powder pasting and spin-coating processes and their gas-sensing performances were evaluated in the temperature range of 200–400 °C under dry and humid air conditions. The test results reported that the optimum Er content of 0.1 wt% provided the optimally high and selective response of 347 to 30 ppm C2H4O with a short response time of ∼2 s and a low detection limit of 18 ppb, which were substantially better than those of undoped one at the best working temperature of 350 °C. The high selectivity was confirmed against CH2O, C3H6O, C2H5OH, NH3, C2H2, C2H4, H2, CH4, H2S, H2O and CO. Besides, the influence of humidity on C2H4O response of Er-doped SnO2 sensor was moderately low over a wide relatively humidity range of 0–80 %. The gas-sensing mechanisms were proposed with a new model describing the catalytic roles of p-type Er dopants to ethylene oxide adsorption.