ZnGa2O4 and ZnGa2O4:N thin films applied as sensors for detection of acetaldehyde in ethanol

Abstract

Acetaldehyde, a byproduct of fermentation, is a highly toxic contaminant. Therefore, it is important to develop cost-effective, fast-response and portable acetaldehyde sensors to monitor the formation of this contaminant in the process. Herein, we have evaluated the potential use of ZnGa2O4 and ZnGa2O4:N (referred as ZnGaON) films as vapor sensors of ethanol containing acetaldehyde. Sensors based on ZnGa2O4 films were successfully prepared by PLD on Al2O3 substrates containing interdigitated Pt electrodes. The nitridation was carried out under NH3 gas flow at 700 °C, to obtain ZnGaON films. The prepared sensors presented high sensitivity to acetaldehyde, allowing identification of acetaldehyde in ethanol (300 ppm). This acetaldehyde concentration corresponds to the limit established by Brazialian legislation to sugarcane alcoholic beverages (cachaça). The ZnGaON sensor should be operated at moderate temperature (450 °C), and response time of 43 s and recovery time of 26 s are quite fast. The results strongly suggest that ZnGaON may be considered a potential candidate for the development of an efficient screening test for a highly sensitive and selective identification of acetaldehyde in beverages, foods, or fuel.