Chemiresistive gas sensors based on electrospun semiconductor metal oxides: A review

Semiconductor metal oxide (SMO) gas sensors have attracted considerable attention for detecting environmental pollution, as well as the accidental leakage of flammable, explosive, and toxic gases. SMOs are known to exhibit high sensitivity, fast response time, and excellent selectivity towards various types of gases. Many new strategies have been implemented to improve these characteristics. Among the materials produced by these methods, nanomaterials (NMs) synthesized by electrospinning have unprecedented advantages, including catalyst introduction, morphological control, thermodynamic stability, unique physicochemical properties, composition adjustment, and rapid adsorption-desorption rates of the NMs, and are appealing for the designing highly sensitive and selective gas sensors. This review highlights the latest findings on the design and fabrication of electrospun gas sensors for detecting various gases including hydrogen (H2), methane (CH4), nitrogen monoxide (NO), hydrogen sulfide (H2S), ammonia (NH3), ethanol (C2H5OH), acetone (CH3COCH3), formaldehyde (HCHO) and toluene (C6H5CH3). Studies have indicated that NMs with different shapes (e.g., nanotubes, nanowires, nanoflowers, nanosheets, nanorods, nanofilms, and nanofibers) and compositions (single-phase SMOs, modified SMOs, nanocomposites of SMOs, and SMOs combined with carbon nanomaterials) display high response values, long-term stability, low humidity dependence, fast response/recovery times, and low detection limits for gases. Finally, conclusions and future perspectives for gas sensors based on the electrospinning technique are discussed.