Synthesis, structure and optimized field emission properties of highly oriented ZnO/Pt core–shell nanorods on a Zn substrate†
This study reports Pt-decorated ZnO nanorod arrays (Pt/ZnO NRs) fabricated by low-cost hydrothermal and sputtering processes, which have excellent field emission (FE) performance. The effects of the Pt thickness on the morphology, structure and FE properties of ZnO NRs were investigated. It was found that highly oriented ZnO NRs with sharp tips were grown on a Zn substrate and the surface of ZnO NRs were uniformly covered with Pt nanoparticles (NPs) with a diameter of around 2–3 nm. The FE properties of ZnO NRs were greatly improved by optimizing the amount of Pt NPs. The results found that the ZnO NR emitters coated with Pt NPs of 15 nm thickness (Pt15/ZnO NRs) exhibited the best FE characteristics, which have the lowest turn-on field at 1.45 V μm−1 and the highest field enhancement factor of around 5405. More importantly, the maximum emission current density of as-fabricated Pt15/ZnO NR emitters was about 1900 times that of the bare ZnO emitters. The Pt coating not only improves electron conduction and heat dissipation of the emitters but also balances the emission point density and the screening effect.