Ultra-sensitive triethylamine sensors based on oxygen vacancy-enriched ZnO/SnO2 micro-camellia

Abstract

The detection of volatile organic gas triethylamine (TEA) is of great significance to environment quality and human health. However, it is still a challenge to achieve high-sensitivity detection at low temperatures. In this work, a TEA sensor with a low operating temperature and high response was successfully prepared by designing ZnO/SnO₂ composite material rich in oxygen vacancy defects. A camellia-like ZnO material was synthesized by a hydrothermal method using surfactant, bis(2-ethylhexyl)sulfosuccinate sodium salt (AOT) as a soft template. SnO₂ nanoparticles with a diameter of 20 nm were dispersed on ZnO nanosheets to form a ZnO/SnO₂ heterostructure. The sensor based on ZnO/SnO₂-10 demonstrates an extremely high response of 780 to 100 ppm TEA. More importantly, the response value of 1 ppm TEA detected is 6 and the detection limit is as low as 0.43 ppm. Besides, the sensor has a low working temperature of 100 °C. The enhancement of TEA sensing performance could be attributed to the synergistic effect of oxygen vacancy (Vo), ZnO–SnO₂ heterojunction, and the ZnO (001) exposure plane. Vo can be used as the active center of oxygen molecule adsorption to produce highly active O₂ ⁻ species. Furthermore, Vo–ZnO has higher adsorption energy for TEA molecules than pure ZnO, which was determined using first-principles calculations, confirming the strong interaction between Vo–ZnO and TEA. The sensor shows a broad application prospect in food safety detection and environmental monitoring.