Nanoparticle-Built Porous Fe2O3/SnO2 Heterojunction Nanotubes by the Microwave-Loading-on-MOF Strategy for Highly Sensitive and Stable n -Butanol Sensing

n-Butanol poses potential risks to both human health and production safety, and its reliable detection is urgent. Herein, nanoparticle-built porous Fe2O3/SnO2 heterojunction nanotubes are synthesized via a microwave-assisted loading of α-Fe2O3 on Sn-metal-organic framework (Sn-MOF) strategy and are utilized as functional materials for detecting n-butanol gas. The Fe2O3/SnO2 composite has a hollow tubular structure, which consists of in situ grown SnO2 nanoparticles and immobilized Fe2O3 nanoparticles. The Fe2O3/SnO2 nanotubes exhibit a high sensing response to n-butanol, and their gas-sensing performance is significantly influenced by the Fe/Sn molar ratio. The Fe2O3/SnO2 composite with an Fe/Sn ratio of 1:9 shows superior sensing properties. At the optimal temperature of 200 °C, it demonstrates an extremely low detection limit of 500 ppb and a high sensitivity of 150 toward 50 ppm n-butanol with a fast response time of merely 5 s. Furthermore, it has presented good stability over an 8-month time span. The enhanced sensing is believed to stem from the synergistic effects of gas adsorption and electron transfer, facilitated by the unique structure and the formed heterojunctions between SnO2 and α-Fe2O3.