Prominent ethanol sensing with Cr2O3 nanoparticle-decorated ZnS nanorods sensors

Abstract

ZnS nanorods and Cr2O3 nanoparticle decorated ZnS nanorods were synthesized using facile hydrothermal techniques and their ethanol sensing properties were examined. X-ray diffraction and scanning electron microscopy revealed the good crystallinity and size uniformity of the ZnS nanorods. The Cr2O3 nanoparticle decorated ZnS nanorod sensor showed stronger response to ethanol than the pristine ZnS nanorod sensor. The responses of the pristine and decorated nanorod sensors to 200 ppm of ethanol at 300oC were 2.9 and 13.8, respectively. Furthermore, under these conditions, the decorated nanorod sensor showed longer response time (23 s) and shorter recovery time (20 s) than those of the pristine one (19 and 35 s, respectively). Consequently, the total sensing time of the decorated nanorod sensor (42 s) was shorter than that of the pristine one (55 s). The decorated nanorod sensor showed excellent selectivity to ethanol over other volatile organic compound gases including acetone, methanol, benzene, toluene, whereas the pristine one failed to show selectivity to ethanol over acetone. The improved sensing performance of the decorated nanorod sensor is attributed to the modulation of the conduction channel width and the potential barrier height at the ZnS Cr2O3 interface accompanying the adsorption and desorption of ethanol gas as well as the greater surface to volume ratio of the decorated nanorods than the pristine one due to the existence of the ZnS Cr2O3 interface.