RGO enveloped vertically aligned Co3O4 nanowires on carbon fabric: a highly efficient prototype for flexible field emitter arrays

Abstract

A surfactant-free new approach is formulated for synthesizing Co₃O₄ nanowires on a flexible carbon fabric substrate by a simple chemical route. The devised protocol yields uniform and highly dense nanowire distributions that are able to sustain their structural and morphological integrities even under severe bending and twisting. To understand the growth process of these Co₃O₄ nanowires on the chemically activated carbon fabric, the morphological evolutions are investigated in a step-by-step manner using FESEM and HRTEM analysis. As-synthesized Co₃O₄ nanowires, endowed with sharp edge features of their morphology, are found to exhibit excellent p-type field emitting traits with a very low turn on field of 0.86 V μm⁻¹ with a significant current density of ∼0.5 mA cm⁻² at a relatively lower applied electric field of ∼1.4 V μm⁻¹. To improve the current density and field enhancement factor even further, RGO sheets are anchored over the Co₃O₄ nanowires so that the conducting RGO sheets could potentially enrich the field emission performance due to its high electron affinity. Thus the designed hybrid nanostructures are found to display a turn-on field of 0.8 V μm⁻¹ and current density twice (1 mA cm⁻²) that of bare Co₃O₄ nanowires. Experimental observations indicate that these hybrid RGO wrapped Co₃O₄ nanostructures are highly promising as cold cathodes in flexible field emission display applications.