Highly Sensitive Ammonia Gas Sensor Based on MWCNTs Saturated Fe₂O₃ Nanograins

Ammonia has a wide range of applications in various branches of industry and technology; the detection of its low concentrations is a preventive method for ambient air quality pollution and a useful method for noninvasive diagnosis of kidney disease by monitoring in exhaled human breath. In this work, a high-performance ammonia sensor based on the Fe₂O₃/MWCNTs (multiwalled carbon nanotubes) material was produced by applying the e-beam deposition method. The morphology, composition, and chemical state of the Fe₂O₃/MWCNTs material were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy (Raman), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The gas-sensing behavior of the sensor to various concentrations of NH₃ was measured at 200 °C, representing excellent gas response and sophisticated performance parameters. The low detection limit of the Fe₂O₃/MWCNTs sensor was 3 ppm of NH₃, corresponding to the response value of 2.7. The promising values of the response and recovery times (40 and 25 s) confirmed the high speed of ammonia detection. Thus, the suggested Fe₂O₃/MWCNTs material that is sensitive to low concentrations of NH₃ can be successfully used in a new generation of ammonia alarm systems.