Amorphous carbon nanotube–polyaniline core–shell nanostructures for efficient cold cathode applications

Abstract

The general challenge to improve the field emission properties of conducting polymers depends on the fabrication of novel nanostructures from their polymeric aggregates and/or the synthesis of novel nanocomposites. Here we report amorphous carbon nanotube (aCNT)–polyaniline (PANI) core–shell hierarchical structures for the first time, which exhibit high field emission properties. The aCNT–PANI hierarchical nanostructures were prepared using a facile and cost effective method, which involved a simple in situ oxidative polymerization of aniline in the presence of aCNTs at three different temperatures. The as-synthesized samples were characterized using X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy and Raman spectroscopy. The field emission characteristics of the pristine aCNT sample were compared with the composites synthesized at different temperatures. The turn-on fields of the aCNT–PANI composites in comparison with the pristine aCNTs decreased from 9.13 to 2.57 V μm−1 and the emission current density increased from 0.031 to 1.27 mA cm−2 at an electric field of 11.50 V μm−1. The improvement in the field emission properties of the aCNT–PANI composites can be explained in terms of both a higher enhancement factor and a lower work function of the composite. This research gives a new perception towards the radical improvement of field emission properties of conducting polymers, based on unique hierarchical core–shell nanostructures.