Synthesis and enhanced field emission of zinc oxide incorporated carbon nanotubes

Zinc oxide (ZnO) nanostructures were successfully incorporated into carbon nanotubes (CNTs) using an arc discharge method. Studies of the morphologies of ZnO incorporated CNTs (ZnO-CNTs) revealed that ZnO nanoparticles were attached on the exterior of CNTs. X-ray diffraction, Raman spectra and cathodoluminescence (CL) spectra revealed the existence of ZnO. The ID/IG ratios from Raman spectroscopy for the CNTs and ZnO-CNTs were 0.44 and 0.51, respectively, suggesting an increased degree of disorder of the CNT walls after the incorporation of ZnO. The deep red CL emission peak at 747 nm originated from ZnO defect emission in ZnO incorporated CNTs. X-ray photoelectron spectroscopy results revealed that sp3-hybridized C[sbnd]O bonds at 286.2 eV in ZnO-CNTs had higher intensities than CNTs, indicating presence of more C[sbnd]O bonds in ZnO-CNTs. A low turn-on field of ~ 1.5 V μm− 1 at a current density of 0.1 μA cm− 2, low threshold field of ~ 2.9 V μm− 1 at a current density of 1 mA cm− 2, high field enhancement factor (5741), and stable emission current were obtained from ZnO-CNTs. The simplicity of synthesis, coupled with the promising emission results, make ZnO-CNTs a promising candidate for low-cost, compact CNT cold cathode materials. © 2016 Elsevier B.V.