Tailored formation of WO3-rGO nanohybrids for dependable low temperature NO2 sensing

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Herein, we report the facile synthesis route of the tungsten oxide (WO3)-reduced graphene oxide (rGO) nanohybrids by the hydrothermal method. The analyses of the WO3-rGO nanohybrid sensor were performed by various techniques, as X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and Brunauer–Emmett–Teller (BET) analyzer. The gas sensing analysis of WO3-rGO (1–5 wt%) nanohybrid sensors has revealed remarkable gas selectivity towards nitrogen dioxide (NO2) out of distinguishing gases viz. ammonia (NH3), carbon monoxide (CO), hydrogen sulfide (H2S), and sulfur dioxide (SO2). An optimal WO3-rGO (3 wt%) nanohybrid sensor has exhibited 252% response to 100 ppm NO2 at an optimized operating temperature (150 °C). The dynamic study of the WO3-rGO (3 wt%) nanohybrid sensor for different NO2 gas concentrations has displayed a clear increasing response trend. The reproducibility and stability of the sensor was confirmed through repeated measurements. Additionally, impedance studies were conducted to further insight the sensing mechanism of WO3-rGO (WR) nanohybrid sensor, shedding light on its electrical response to gas interactions. The WR nanohybrid sensors have exhibited promising gas sensing performance, indicating its potential for practical applications in areas like air quality monitoring, emission control, workplace safety, and other pertinent fields.