Controllable Ag nanoparticle coated ZnO nanorod arrays on an alloy substrate with enhanced field emission performance

Abstract

Ag–ZnO nanocomposites were prepared on alloy substrates by two simple and inexpensive steps, i.e. synthesis of ZnO nanorod arrays (ZNAs) by a low-temperature hydrothermal method, followed by electrophoretic deposition method to coat ZNAs with Ag nanoparticles (NPs). The sizes and densities of the Ag NPs could be facilely adjusted by changing the deposition time. The field emission (FE) performances of Ag–ZnO emitters were improved greatly by adjusting the sizes and densities of the Ag NPs, and the optimized FE performance of the Ag–ZnO emitter was obtained with the lowest turn-on field of 0.86 V μm⁻¹ and a current density up to 7.96 mA cm⁻² at 4.45 V μm⁻¹. More importantly, the Ag–ZnO emitter exhibited excellent current stabilities with 1900 min operation under only 6.5% current fluctuation. These results suggest that the Ag–ZnO composite is a promising cathode material for fabrication of future FE devices.