Visible light boosting hydrophobic ZnO/(Sr0.6Bi0.305)2Bi2O7 chemiresistor toward ambient trimethylamine

Abstract Though UV illumination has been widely adopted to activate the room temperature response of metal oxide based chemiresistors, photoexcited abundant carriers (low base resistance) induced low response, and UV induced hydrophilicity caused degradation or even poisoning in ambient humid air atmosphere, pose a challenge for real applications. Herein, 15 mol% (optimized ratio) ZnO nanoparticles have been coupled into hydrophobic (Sr0.6Bi0.305)2Bi2O7 (SBO) matrix, hydrophobic ZnO/SBO chemiresistor has been proposed. Visible 455 nm light could not only trigger the gas/oxide interfacial charge exchange, but also substantially reduce the carrier concentration of chemiresistor in comparison with UV 365 nm light, and therefore noticeably boosts trimethylamine (TMA) response at room temperature, including an enlarged sensitivity, extremely low limit of detection (LoD) (10 ppb), good selectivity, reproducibility and long-term stability. More importantly, present hydrophobic ZnO/SBO chemiresistor could be operated under high relative humidity (RH 90%) with a slight decline (17%) of response with respect to dry air background, opening an opportunity for the practical applications of oxide chemiresistors in ambient humid atmosphere.