Highly sensitive and selective ethanol and acetone gas sensors based on modified ZnO nanomaterials

Nowadays, highly sensitive metal oxide semiconductor gas sensors are exerting a growing important influence on the detection of target gases. It is still challenging to get both high sensitivity and selectivity to effectively distinguish gas mixtures. In this study, Mn doped ZnO (MZO) is prepared by a facile co-precipitation method and then further modified by CdO addition. The results show that 2.2mol% MZO has high responses to both acetone and ethanol, while 10 mol% CdO activated 1mol% MZO exhibits excellent sensitivity to ethanol and neglectable response to acetone. This is explained by the enhanced alkalinity of ZnO by the CdO addition expelling acetone from adsorption onto the sensor surface, which is verified by temperature–programmed CO2 desorption. Moreover, the CdO-MZO gas sensor has an optimized working temperature of 240°C, far lower than 340°C of MZO, due to the higher oxidativity as proved by the temperature-programmed H2 reduction. The MZO and CdO-MZO gas sensors are then used as a sensor array to distinguish the ethanol and acetone concentrations in mixtures with varied ratios, showing the promise of the gas sensor property tailoring approach for future high performance gas sensors.