The Synthesis of Zinc Oxide/Carbon Spheres Nanocomposites and Field Electron Emission Properties

Abstract

Zinc oxide (ZnO)/carbon spheres (CS) nanocomposites were successfully synthesised using waste engine oil as precursor for the CS production. ZnO nanorods were grown using sol-gel immersion method with MgZnO as the seeded catalyst and thermal chemical vapour deposition was used to synthesise CS. Different configurations of ZnO/CS structures were prepared i.e. CScoated ZnO and ZnO-coated CS. The structures of composite samples were analysed using field emission scanning electron microscopy (FESEM), Energy-Dispersive X-ray (EDX), micro-Raman and X-ray Diffraction Spectroscopy (XRD). FESEM observations revealed the structural changes of pristine ZnO and CS in composite structures. The as-present of ZnO or CS was believed to affect the subsequent growth of another structure. Field electron emission (FEE) properties of both nanocomposites were also investigated. It was found that ZnO-coated CS sample has better FEE properties with lower turn-on (3.48 Vµm-1) and threshold field (6.35 Vµm-1) obtained at current density of 0.1 and 1 µAcm-2 , respectively. This study highlighted that nanocomposites of ZnO and CS have successfully enhanced the field emission performances of materials compared with pristine ZnO or CS due to the structural changes of material emitter.