High-Performance Ammonia Gas Sensors Based on Plasma Treated Carbon Nanostructures

Sensors based on multi-walled carbon nanotubes were functionalized by oxygen plasma treatment and plasma co-polymerization of maleic anhydride and acetylene, obtaining core-shell carbon nanopartices covered by functional groups. The active nanostructured carbonaceous material was investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. It was confirmed that plasma treatment increases the content of surface functional groups. The sensing properties of the functionalized material were measured in the range of 10-1000 ppm of NH3at room temperature. The plasma treated sensor showed an extremely high response of 22.5%, 27.9%, and 31.4% to 100 ppm, 250 ppm, and 500 ppm of NH3, respectively. It was shown that the nature of NH3adsorption on the surface of functionalized nanostructured carbon material is physical adsorption.