Preparation and bifunctional gas sensing properties of porous In O-CeObinary oxide nanotubes

The porous binary InO-CeOoxides nanotubes (NTs) in cubic phase were first fabricated by electrospinning (ESP) method and characterized by SEM, TEM, XRD, XPS and UV-vis absorption techniques. By adjusting the InOand CeOmolar ratio, the out diameters and wall thicknesses of the final composites were tuned ranging of 90-180 nm and 15-9 nm, respectively. The band gap of the binary oxides gradually decreases, and the ratio of Ceto Ceincreases with the increase of CeO, implying that surface oxygen vacancies gradually increase. The gas sensing test reveals that when the content of CeOis appropriate, the as fabricated InO -CeONTs could be bifunctional gas sensors to detect HS at low temperature(25-110 °C) while acetone at relative high temperature (300 °C). The InCeNTs sensor is an optimum one, which exhibits the highest response of 498 to HS at 80 °C and the highest response of 30 to acetone at 300 °C. In contrast to the pure InOsensor, the response and recovery times, as well as the sensing reaction barrier height, for InCe both degrade considerably. The above temperature-dependent sensing properties were attributed to two different gas sensing mechanisms, sulfuration at low temperature and adsorption at high temperature. © 2010 American Chemical Society.