Rational design of ordered porous SnO_2/ZrO_2 thin films for fast and selective triethylamine detection with humidity resistance

摘要

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 SnO_2/ZrO_2 porous thin films with a three-dimensionally ordered microstructure (3DOM). The 3DOM ZrO_2 fabricated by a template method serves as a hydrophobic layer and SnO_2 deposited on ZrO_2 by atomic layer deposition (ALD) acts as the transducer layer. Gas sensing tests reveal the SnO_2/ZrO_2 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 SnO_2/ZrO_2 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 3D0M ZrO_2 layers, which forms an air hydrophobic layer to suppress water adsorption. Furthermore, the SnO_2/ZrO_2 sensor also possesses superior selectivity, long-time stability and a low detection limit of 40 ppb, thereby endowing a potential toward practical TEA detection.