Abstract
Gas sensors play a crucial part in air monitoring and exclusive detection of exhaled biomarkers. Co3O4 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 Fe2O3 is desired to enhance the conductivity and regulate oxygen-vacancy defects. Thus, the Fe2O3@Co3O4 double-shelled nanotubes (DSNTs) for ethanol detection were successfully synthesized through a facile coaxial electrospinning route. The Fe2O3@Co3O4-1 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 Co3O4 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.
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