Carbon Micronymphaea: Graphene on Vertically Aligned Carbon Nanotubes

Abstract

This paper describes the morphology of carbon nanomaterials such as carbon nanotube (CNT), graphene, and their hybrid structure under various operating conditions during a one‐step synthesis via plasma‐enhanced chemical vapor deposition (PECVD). We focus on the synthetic aspects of carbon hybrid material composed of heteroepitaxially grown graphene on top of a vertical array of carbon nanotubes, called carbon micronymphaea. We characterize the structural features of this unique nanocomposite by uses of electron microscopy and micro‐Raman spectroscopy. We observe carbon nanofibers, poorly aligned and well‐aligned vertical arrays of CNT sequentially as the growth temperature increases, while we always discover the carbon hybrids, called carbon micronymphaea, at specific cooling rate of 15°C/s, which is optimal for the carbon precipitation from the Ni nanoparticles in this study. We expect one‐pot synthesized graphene‐on‐nanotube hybrid structure poses great potential for applications that demand ultrahigh surface‐to‐volume ratios with intact graphitic nature and directional electronic and thermal transports.