Preparation, Characterization, and Mechanistic Understanding of Pd‐Decorated ZnO Nanowires for Ethanol Sensing

Abstract

ZnO nanowires (ZnO‐NWs) and Pd‐decorated ZnO nanowires (Pd‐ZnO‐NWs) were prepared by hydrothermal growth and characterized by scanning electron microscopy (SEM) and X‐ray diffraction (XRD). When used for gas sensing, both types of nanowires showed a good selectivity to ethanol but a higher sensitivity and lower operating temperature were found with Pd‐ZnO‐NWs sensors comparing to those of ZnO‐NWs sensor. When exposed to 200 ppm ethanol, our ZnO‐NWs sensor showed a sensitivity of about 2.69 at 425°C whereas 1.3 at. % Pd‐ZnO‐NWs sensor provided a 57% more detection sensibility at 325°C. In addition, both response and recovery times of Pd‐ZnO‐NWs sensors were significantly reduced (9 s) comparing to the ZnO‐NWs. Finally, Pd‐ZnO‐NWs sensor also showed a much lower detection limit of about 1 ppm. The sensing mechanism of Pd‐ZnO‐NWs sensors has also been clarified, thereby providing a new perspective for further improvement of the sensing performance of ethanol sensors.