Detection of ppb-level NO2 gas using a portable gas-sensing system with a Fe2O3/MWCNTs/WO3 sensor using a pulsed-UV-LED

A portable gas-sensing system which is periodically irradiated with light from a pulsed ultraviolet light emitting diode (UV-LED) was fabricated for sensing ppb-level NO2 gas. The portable NO2 gas-sensing system includes a device manager coupled to a pulsed-UV-LED sensing module, a liquid-crystal display module and a data capture module. The sensor made of a composite iron oxide/multi-walled carbon nanotubes/tungsten oxide (Fe2O3/MWCNTs/WO3) material was produced by a one-pot polyol method followed by metal organic decomposition (MOD). Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) were used to analyze the structure and morphology of the fabricated films. The effects of the wavelength and duration of the irradiation on the response of the portable gas-sensing system for sensing NO2 gas were studied. This portable gas-sensing system in periodically pulsed-UV-LED operation mode exhibited high sensitivity, good linearity, good stability, high reproducibility, a low detection limit and high selectivity in the sensing of NO2 gas.