Preparation and field emission properties of Er-decorated multiwalled carbon nanotubes

The field emission of multiwalled carbon nanotubes (MWCNTs) was improved after decorating their external surface with erbium (Er)-nanoparticles. The decoration was performed by liquid-phase reduction using ethylene glycol as the reducing agent. The oxidation of MWCNTs and the attachment of Er-nanoparticles on the surface of MWCNTs were confirmed by transmission electron microscopy and energy-dispersive X-ray spectroscopy. Raman spectroscopy also revealed the oxidation and functionalization of the nanotubes. Thermogravimetric analysis showed that the decomposition temperature of the MWCNTs decreased gradually as a result of the oxidation process and sequential decoration with uniformly sized Er-nanoparticles (2–3 nm). This means that some of the defects formed by oxidation and decoration with Er-nanoparticles reduced the ignition temperature of the MWCNTs. After decoration with Er-nanoparticles, the MWCNTs showed a significantly better emission current density (3.45 mA/cm2 at 3.98 V/μm) and turn-on field (1.8 V/μm) than the pristine MWCNTs.