The effect of surface morphology on the response of Fe2O3-loaded vanadium oxide nanotubes gas sensor

The effect of surface morphology on the response of an ethanol sensor based on vanadium nanotubes surface loaded with Fe₂O₃ nanoparticles (Fe₂O₃/VONTs) was investigated in this work. The particle size of Fe₂O₃ loaded on VONTs was varied by using novel citric acid-assisted hydrothermal method. In the synthesis progress, citric acid was used as a surfactant and chelate agent, which ensured the growth of a uniform Fe₂O₃ loading on the nanotubes surface. The ethanol sensing properties was then measured for these Fe₂O₃/VONTs at 230-300 °C. The results showed that the sensor response increased with the particles size and the loading amount of Fe₂O₃. It appears that the load of Fe₂O₃ on the VONTs surface increases the concentration of oxygen vacancies and decreases the concentration of free electrons. The effects of morphology on the sensor resistance were interpreted in terms of the Debye length and the difference in the number of active sites.