Large-Diameter Graphene Nanotubes Synthesized Using Ni Nanowire Templates

Abstract

We report a method to synthesize tubular graphene structures by chemical vapor deposition (CVD) on Ni nanowire templates, using ethylene as a precursor at growth temperature of around 750 °C. Unlike carbon nanotubes that are synthesized via conventional routes, the number of graphene layers is determined by the growth time and is independent of the tube diameter and tube length, which follow those of the nanowire template. This allows us to realize large-diameter tubes with shells comprising a few or many layers of graphene as desired. Thin graphene layers are observed to be highly crystalline, and of uniform thickness throughout the length of the nanowire. Raman analysis shows the presence of a small level of defects typical of CVD-grown graphene. The metallic core could be removed by chemical etching to result in a collapsed tube. Backgated field-effect transistor measurements were conducted on the collapsed graphene tube. This approach to the realization of tubular graphene offers new opportunities for graphene-based nanodevices.

3D graphene foam-supported cobalt phosphate and borate electrocatalysts for high-efficiency water oxidation

“…Two characteristic peaks at *1,580 cm -1 (G-band) and *2,700 cm -1 (2D-band) are observed. The intensity ratio of 2D-band to G-band (I 2D /I G ) is related to the number of layers of graphene (\5 layers) [20,21], which is consistent with the result of TEM. Extremely weak D-band (*1,350 cm -1 ) in Fig.…”

Bulk scale growth of CVD graphene on Ni nanowire foams for a highly dense and elastic 3D conducting electrode

“…3(b) and S5, 3D graphene foams exhibit a highly dense and interconnected porous structure over a large area after the Ni etching process, although slightly wrinkled and folded morphologies are observed in the magnified image of Fig. 3(b) [27]. Successful etching of a Ni catalyst without residues was confirmed by both XRD and EDS analysis of the 3D graphene foams before and after the etching process (Fig.…”

Design Considerations for Unconventional Electrochemical Energy Storage Architectures

“…Moreover, graphene growth is known to be surface catalyzed only by some materials further limiting the applicability. [ 594,595 ] Nevertheless, graphene growth on active battery materials remains highly desirable as it can ensure highly intimate and conformal contact, create a stable passivation layer as well as keep the structural integrity and avoid dissolution of active species. Mild chemistries for carbon nanosheets growth have been recently proposed and although this can be realized even at room temperature, defect free application of such versatile coatings remains the subject of further developments.…”