Mass production of highly-porous graphene for high-performance supercapacitors

Abstract

This study reports on a facile and economical method for the scalable synthesis of few-layered graphene sheets by the microwave-assisted functionalization. Herein, single-layered and few-layered graphene sheets were produced by dispersion and exfoliation of functionalized graphite in ethylene glycol. Thermal treatment was used to prepare pure graphene without functional groups, and the pure graphene was labeled as thermally-treated graphene (T-GR). The morphological and statistical studies about the distribution of the number of layers showed that more than 90% of the flakes of T-GR had less than two layers and about 84% of T-GR were single-layered. The microwave-assisted exfoliation approach presents us with a possibility for a mass production of graphene at low cost and great potentials in energy storage applications of graphene-based materials. Owing to unique surface chemistry, the T-GR demonstrates an excellent energy storage performance, and the electrochemical capacitance is much higher than that of the other carbon-based nanostructures. The nanoscopic porous morphology of the T-GR-based electrodes made a significant contribution in increasing the BET surface as well as the specific capacitance of graphene. T-GR, with a capacitance of 354.1 Fg−1 at 5 mVs−1 and 264 Fg−1 at 100 mVs−1, exhibits excellent performance as a supercapacitor.

Photocatalytic Graphene-TiO2 Thin Films Fabricated by Low-Temperature Ultrasonic Vibration-Assisted Spin and Spray Coating in a Sol-Gel Process

“…Ti-O vibration is identified at 670 cm −1 . The left shoulder absorption band at 807 cm −1 and the minor peaks around 2800-3100 cm −1 are consistent with Ti-O-C binding, showing the chemisorption between TS and GD solutions [15,28]. The same peaks (2800-3100 cm −1 ) may be attributed to metal (in this case, Ti) and methyl groups (Ti-CH x ), as well [29].…”

“…The weak reflection at 3450 cm −1 shows -OH stretching due to the hydroxyl groups attached to graphene planes [17,28]. The FTIR spectrum of the TS:GD solution presents some additional peaks (Figure 2b).…”

“…Typical graphene features appearing in both spectra are as follows: superimposed sharp peaks at 950-1100 cm −1 reflect C-O stretching on graphene surface, due to the presence of a small percentage of oxygen in the graphene used in this study. The bold signals at 1250, 1327 and 1385 cm −1 represent shifted C-O-C, C-O···H or C-O bindings, and imply interlinking of unsaturated -C and -OH groups in alcohols [28].…”

New functionalization of graphene oxide with N2O2ligand for efficient loading of Cu nanostructures as a heterogeneous nanocatalyst for the synthesis of β‐hydroxy‐1,2,3‐triazoles

“…There are some prominences on the surface of GO which indicate successful immobilization of organic ligands and Cu nanostructures. According to the three‐dimensional image, the thickness of the functionalized GO layer is about 16 nm which proves the nanosheet‐like structure of the catalyst …”

“…As explained in the previous section, since copper nanoparticles are sensitive to oxygen in the air, they can be oxidized to copper(I) oxide (Cu 2 O) . Thus, there are some extra peaks in the PXRD pattern attributed to Cu(I) (Cu 2 O) that are positioned at 2 Ɵ = 29.7°, 36.5°, 42.3°, 61.3° and 73.5°, corresponding to the (111), (200) (220) and (311) planes of copper oxide …”