NO2 and CO interaction with plasma treated Au-decorated MWCNTs: Detection pathways

The detection mechanisms of gas sensors based on oxygen plasma functionalised multi wall carbon nanotubes (MWCNTs) and rf plasma-treated nanotubes decorated with gold nanoclusters are experimentally and theoretically investigated. Results from X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) analysis are discussed. It is found that NO2 detection involves the interaction with oxygenated vacancies and/ or Au nanoclusters present on the nanotube walls, while CO detection is significantly enhanced by the interaction with Au nanoclusters anchored at the nanotube sidewalls. These differences in detection pathways open the possibility for fabricating selective MWCNT sensors.