Abstract:
Methanol vapour is harmful to human health if it is inhaled, swallowed, or absorbed through the skin. Solidstate
gas sensors are a promising system for the detection of volatile organic compounds, unfortunately,
they can have poor gas selectivity, low sensitivity, an inferior limit of detection (LOD), sensitivity towards
humidity, and a need to operate at higher temperatures. A novel solid-state gas sensor was assembled
using carbon nanoparticles (CNPs), prepared from a simple pyrolysis reaction, and zinc oxide@zeolitic
imidazolate framework-8 nanorods (ZnO@ZIF-8 nanorods), synthesised using a hydrothermal method.
The nanomaterials were characterized using scanning electron microscopy, transmission electron
microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy Raman spectroscopy, and
Fourier transform infrared spectroscopy. The ZnO@ZIF-8 nanorods were inactive as a sensor, the CNPs
showed some sensor activity, and the CNPs/ZnO@ZIF-8 nanorod composite performed as a viable solidstate
sensor. The mass ratio of ZnO@ZIF-8 nanorods within the CNPs/ZnO@ZIF-8 nanorod composite
was varied to investigate selectivity and sensitivity for the detection of ethanol, 2-propanol, acetone,
ethyl acetate, chloroform, and methanol vapours. The assembled sensor composed of the CNPs/
ZnO@ZIF-8 nanorod composite with a mass ratio of 1.5 : 6 showed improved gas sensing properties in
the detection of methanol vapour with a LOD of 60 ppb. The sensor is insensitive to humidity and the
methanol vapour sensitivity was found to be 0.51 U ppm 1 when detected at room temperature.
