Ethanol gas sensor based on Al-doped ZnO nanomaterial with many gas diffusing channels

ZnO nanomaterial with multi-microstructures is synthesized by using normal pressure thermal evaporation and then doped with different Al2O3 contents by grinding in an agate mortar. The as-prepared Al-doped ZnO nanomaterials are characterized by X-ray diffraction and scanning electron microscopy. The characterization results show that all the compounds are wurtzite with hexagonal structure and are well crystallized. Channels/connecting holes arising from many kinds of ZnO microstructures are abundant. Both annealing and Al2O3-doping contributes to an increase in the quasi-one-dimensional and tridimensional microstructures. The as-prepared Al-doped ZnO nanomaterials show excellent gas responses to ethanol. The sensing mechanism of the ZnO-based nanomaterials with multi-microstructures is further analyzed by using the Effective Specific Surface Model. Excellent sensitivity (similar to 200) companied with short response time (similar to 8 s) and recovery time (similar to 10s) to 3000 ppm ethanol is obtained with a ZnO-based sensor with 2 at.% Al2O3 at the operating temperature of similar to 290 degrees C after the sensor is annealed at 500 degrees C. (C) 2009 Elsevier B.V. All rights reserved.