Ethanol sensing properties of pure and Au modified ZnO nanowires

Hydrothermally grown zinc oxide (ZnO) nanowires network has been modified with thin Au layer (similar to 10 nm) to realize an ethanol sensor. The sensor films detected ethanol with maximum response at an operating temperature of 325 degrees C. Incorporation of Au not only enhances the sensor response but also improves the reaction kinetics towards ethanol. The response and recovery times for Au modified sensor films towards 50 ppm of ethanol at 325 degrees C were 5 and 20 s, respectively. This faster reaction kinetics is attributed to the role of Au in improving the sensing properties as per the electronic sensitization mechanism and its nano-Schottky barriers type junction with ZnO. Nano-Schottky barrier type junction has been attributed further to an increase in resistance for Au modified ZnO. Work function measurements performed using Kelvin probe technique further corroborates the findings. (C) 2012 Elsevier B. V. All rights reserved.