Highly-sensitive H2S sensors based on flame-made V-substituted SnO2 sensing films

Abstract

In the present work, 0–2wt% vanadium (V)-doped SnO2 nanoparticles synthesized by flame spray pyrolysis were systematically studied for H2S detection. The sensing films (∼15–20μm in thickness) were homogeneously prepared by spin coating technique on Au/Al2O3 substrates. Structural characterizations by electron microscopy and X-ray analysis confirmed the formation of agglomerated SnO2 nanoparticles (5–20nm) with highly crystalline tetragonal-cassiterite SnO2 structure and V substitutional doping with mainly V5+ oxidation state. The gas-sensing studies revealed that the H2S response of flame-made SnO2 nanoparticles was significantly enhanced by V doping at a very low concentration of 0.1wt% but the response steadily degraded as the V-doping level increases further up to 2wt%. In particular, the 0.1wt% V-doped SnO2 sensor exhibited a very high response of 2274 with a short response time of 2.0s to 10ppm of H2S at 350°C. Moreover, the V-doped SnO2 sensor displayed high H2S selectivity against NO, NO2, SO2, H2, C2H5OH and CH4. Hence, the flame-made V-doped SnO2 sensor is a promising candidate for highly sensitive and selective of H2S monitoring and may be useful for general industrial applications.