We have evaluated some of the most recent breakthroughs in the synthesis and applications of graphene and graphene-based nanomaterials. This review includes three major categories. The first section consists of an overview of the structure and properties, including thermal, optical, and electrical transport. Recent developments in the synthesis techniques are elaborated in the second section. A number of top–down strategies for the synthesis of graphene, including exfoliation and chemical reduction of graphene oxide, are discussed. A few bottom–up synthesis methods for graphene are also covered, including thermal chemical vapor deposition, plasma-enhanced chemical vapor deposition, thermal decomposition of silicon, unzipping of carbon nanotubes, and others. The final section provides the recent innovations in graphene applications and the commercial availability of graphene-based devices.
The development of high volumetric
or areal capacitance energy
storage devices is critical for the future electronic devices. Hence,
the hunting for next-generation electrode materials and their design
is of current interest. The recent work in the two-dimensional metal
hydroxide nanomaterials demonstrates its ability as a promising candidate
for supercapacitor due to its unique structure and additional redox
sites. This study reports a design of freestanding high-mass-loaded
copper-cobalt hydroxide interconnected nanosheets for high-volumetric/areal-performance
electrode. The unique combination of hydroxide electrode with high
mass loading (26 mg/cm
2
) exhibits high areal and volumetric
capacitance of 20.86 F/cm
2
(1032 F/cm
3
) at a
current density of 10 mA/cm
2
. This attributes to the direct
growth of hydroxides on porous foam and conductivity of copper, which
benefits the electron transport. The asymmetric supercapacitor device
exhibits a high energy density of 21.9 mWh/cm
3
, with superior
capacitance retention of 96.55% over 3500 cycles.
A two-step, low-temperature thermal chemical vapor deposition (CVD) process, which uses camphor for synthesizing continuous graphene layer on Cu substrate is reported. The growth process was performed at lower temperature (800 °C) using camphor as the source of carbon. A threezone
CVD system was used for controlled heating of precursor, in order to obtain uniform graphene layer. As-grown samples were characterized by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). The results show the presence of 4–5 layers of graphene.
As-grown graphene transferred onto a glass substrate through a polymer-free wet-etching process, demonstrated transmittance ~91% in visible spectra. This process of synthesizing large area, 4–5 layer graphene at reduced temperature represents an energy-efficient method of producing graphene
for possible applications in opto-electronic industry.
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