Coaxial electrospinning Fe2O3@Co3O4 double-shelled nanotubes for enhanced ethanol sensing performance in a wide humidity range

• Fe 2 O 3 @Co 3 O 4 double-shelled nanotubes were synthesized by a facile coaxial electrospinning route. • The optimized Fe 2 O 3 @Co 3 O 4 sensor exhibited low detection limit, higher sensitivity and moisture resistance to ethanol. • Oxygen adsorption model and energy band structure diagram were proposed to explain the enhanced sensing mechanism. Fe 2 O 3 @Co 3 O 4 double-shelled nanotubes based ethanol sensor with excellent repeatability and long-term stability, lower concentration detection, sensitively under high humidity conditions. Gas sensors play a crucial part in air monitoring and exclusive detection of exhaled biomarkers. Co 3 O 4 is regarded as a promising gas sensing material in lower temperatures (<200 °C) due to its affinity with oxygen and multivalent characteristics. However, its poor intrinsic conductivity leads to a lower response, hindering further practical applications. The introduction of Fe 2 O 3 is desired to enhance the conductivity and regulate oxygen-vacancy defects. Thus, the Fe 2 O 3 @Co 3 O 4 double-shelled nanotubes (DSNTs) for ethanol detection were successfully synthesized through a facile coaxial electrospinning route. The Fe 2 O 3 @Co 3 O 4 -1 DSNTs based sensor exhibited a lower detection limit (1 ppm) at 160 °C, and a remarkable response 3.5 times higher than that of pure Co 3 O 4 HNTs. The sensor still maintained a good response even under a high humidity of 85%. An oxygen adsorption model combined with an energy band structure diagram was proposed to explain the enhanced sensing mechanism. The enhanced gas-sensing performance can be attributed to double-shelled hollow structures and heterojunctions, which promoted the active sites for gas adsorption on the surface of sensing layers.