Rational design of ordered porous SnO2/ZrO2 thin films for fast and selective triethylamine detection with humidity resistance

Abstract

Current gas sensors based on metal oxide semiconductors still suffer greatly from the poor selectivity and low tolerance to the high relative humidity (RH). Herein, we report a highly selective and humidity-resistant gas sensor based on SnO2/ZrO2 porous thin films with a three-dimensionally ordered microstructure (3DOM). The 3DOM ZrO2 fabricated by a template method serves as a hydrophobic layer and SnO2 deposited on ZrO2 by atomic layer deposition (ALD) acts as the transducer layer. Gas sensing tests reveal the SnO2/ZrO2 sensor has a decent response to triethylamine (TEA), a highly toxic and flammable chemical widely used in industry. The sensor exhibits an ultrafast response and recovery (∼ 1 s) speed to 20 ppm TEA at an optimum operating temperature of 190 °C. When the RH increases from 50 % to 90 %, the response of SnO2/ZrO2 sensor shows a minor decrease of 18 %, which to our best knowledge surpasses the existing reports on TEA detection under high RH. The humidity resistance is attributed to continuous 3DOM ZrO2 layers, which forms an air hydrophobic layer to suppress water adsorption. Furthermore, the SnO2/ZrO2 sensor also possesses superior selectivity, long-time stability and a low detection limit of 40 ppb, thereby endowing a potential toward practical TEA detection.