| Summary: | Room-temperature gas sensors based on granulated carbon nanofiber material were investigated for the detection of NO<sub>2</sub>. The granulated material consisting of intertwined carbon nanofibers was synthesized by the decomposition of CH<sub>4</sub> over the Ni/Al<sub>2</sub>O<sub>3</sub> catalyst in a vibro-fluidized bed reactor. Carbon material was investigated using transmission electron microscopy, Raman spectroscopy, low-temperature nitrogen adsorption, and X-ray photoelectron spectroscopy. Investigation of the gas sensors towards NO<sub>2</sub> at room temperature (25 ± 2 °C) was carried out in a dynamic flow-through setup in the range from 1 to 500 ppm. A comparison of the sensitivity gas sensor to NH<sub>3</sub> and CH<sub>4</sub> was also given. The sensor based on non-treated carbon nanofiber material showed the response ΔR/R<sub>0</sub> of 5.1 % to 10 ppm of NO<sub>2</sub>. It was found that the sensor response to NO<sub>2</sub> decreased when increasing the relative humidity. The effect of the relative humidity was more pronounced for low concentrations of nitrogen dioxide and decreases with a further increase in them.
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