Improved field emission of few-layer graphene–carbon nanotube composites by high-temperature processing

Abstract

Self-assembled few-layer graphene–carbon nanotube (FLG–CNT) composites were prepared and their field emission (FE) properties before and after high-temperature (H-T) processing were investigated. It was found that their FE performance deteriorated slightly when they were processed at 1273K for 5h before the FE tests; the applied field increased ~0.05V/μm at 10mA/cm2. X-ray photoelectron spectroscopy analysis indicates that the decreased amount of SP3-hybridized defects from 39.91% to 23.87% after the H-T processing directly leads to this FE degradation. However, the largest emission current density (Jmax) of the FLG–CNT composites increased from 33.48 to 64.00mA/cm2 after the H-T processing. This improved FE performance was attributed to the enhanced adhesion between the CNT and substrates. We consider that the catalyst wrapping at the CNT foot after the H-T processing is responsible for this CNT–substrate reinforcement.