Growth of graphitic carbon layers around silicon carbide nanowires

Abstract

We demonstrate the ability to synthesize graphitic carbon sheets around cubic silicon carbide nanowires via an alloy-mediated catalytic process. The transmission electron microscopy analysis shows multilayer graphitic carbon sheets with a large interatomic layer distance of ~0.45nm, suggesting the presence of oxygen in the graphitic system. Oxygenrelated peaks observed by energy-dispersive X-ray spectroscopy, Raman spectroscopy and Fourier-transform infrared spectroscopy further confirm the oxidation of the graphitic carbon layers. A detailed investigation of the Raman spectra reveals a turbostratic stacking of the graphitic carbon layers. The turbostratic nature and the presence of oxidation in the graphitic carbon surrounding the silicon carbide nanowires makes them a suitable platform for further functionalisation, of particular interest for bio-sensing, as both graphitic carbon and silicon carbide are bio-compatible.

Enhanced Absorption with Graphene-Coated Silicon Carbide Nanowires for Mid-Infrared Nanophotonics

“…In Figure 5c, the Raman spectrum of bare SiC NWs revealed the TO and LO phonon modes at 797 cm −1 and 973 cm −1 , respectively, which are the characteristics of 3C-SiC. The LO peak is convoluted with the Raman response from the silicon substrate, as expected [36,51,59]. Extremely weak peaks around the positions of the D and G bands of graphene are observed for the bare 3C-SiC NWs, showing a negligible extent of unintended graphitization of the wires.…”

Enhanced Mid -Infrared Reflectance with Graphene Coated Silicon Carbide Nanowires

“…2 d-f). Our previous observation of this material system indicated the presence of a low-density oxide layer between graphene and SiC NWs [13]. After including an oxide layer in our graphene/SiC NW/Si FEM model, we observe an additional mode and further reflectance enhancements (Fig 1b, red line).…”

“…The SiC NWs are grown on a silicon substrate as a nanowire forest (see inset in Fig. 1a), with an average diameter around 30-50 nm, and are subsequently graphitized according to our catalytic alloy method [13]. In the FEM, a single nanowire of 50 nm diameter was simulated with periodic boundary conditions.…”

Graphitic‐Based Solid‐State Supercapacitors: Enabling Redox Reaction by In Situ Electrochemical Treatment

“…This mechanism leads to a simple, in-situ preparation of functionalized electrodes, which is the key to triggering redox reactions and enhancing the EDLC performance. In addition, the elevated amount of oxygen functional groups induced on the graphitic surface by the functionalization process is expected to significantly increase the graphene inter-layer spacing, potentially up to ~0.45 nm as we have recently shown [49] . An increased inter-layer spacing, as well as an anticipated improved wettability of the graphitic electrodes due to the functionalization, would enable the PVA molecules to diffuse more efficiently between the electrode layers and intercalate the graphene, overall greatly enhancing the total extent of electrode/electrolyte interface in the cell, hence the EDLC capacitance (see schematic in Figure 6).…”

“…The FTIR spectrum of the as-prepared oxidized electrodes in Figure 5b shows peaks related to the 3C-SiC, TO peak at 794 cm -1 , LO at 970 cm -1 , in addition to a peak around 1060 cm -1 which is commonly attributed to the epoxy functional groups and a peak at ~1225 cm -1 which originates from the hydroxyl functional groups [49][50][51][52] . FTIR spectra of the oxidized electrodes after the insitu electrochemical treatment confirm the enhanced presence of oxygen functional groups on the surface (Figure 5b and S7).…”