3 research outputs found
Improved Electrical Conductivity of Graphene Films Integrated with Metal Nanowires
Polycrystalline graphene grown by chemical vapor deposition
(CVD)
on metals and transferred onto arbitrary substrates has line defects
and disruptions such as wrinkles, ripples, and folding that adversely
affect graphene transport properties through the scattering of the
charge carriers. It is found that graphene assembled with metal nanowires
(NWs) dramatically decreases the resistance of graphene films. Graphene/NW
films with a sheet resistance comparable to that of the intrinsic
resistance of graphene have been obtained and tested as a transparent
electrode replacing indium tin oxide films in electrochromic (EC)
devices. The successful integration of such graphene/NW films into
EC devices demonstrates their potential for a wide range of optoelectronic
device applications
Scalable Synthesis and Characterization of Multilayer γ‑Graphyne, New Carbon Crystals with a Small Direct Band Gap
γ-Graphyne
is the most symmetric sp2/sp1 allotrope of carbon,
which can be viewed as graphene uniformly expanded
through the insertion of two-carbon acetylenic units between all the
aromatic rings. To date, synthesis of bulk γ-graphyne has remained
a challenge. We here report the synthesis of multilayer γ-graphyne
through crystallization-assisted irreversible cross-coupling polymerization.
A comprehensive characterization of this new carbon phase is described,
including synchrotron powder X-ray diffraction, electron diffraction,
lateral force microscopy, Raman spectroscopy, infrared spectroscopy,
and cyclic voltammetry. Experiments indicate that γ-graphyne
is a 0.48 eV band gap semiconductor, with a hexagonal a-axis spacing of 6.88 Ã… and an interlayer spacing of 3.48 Ã…,
which is consistent with theoretical predictions. The observed crystal
structure has an aperiodic sheet stacking. The material is thermally
stable up to 240 °C but undergoes transformation at higher temperatures.
While conventional 2D polymerization and reticular chemistry rely
on error correction through reversibility, we demonstrate that a periodic
covalent lattice can be synthesized under purely kinetic control.
The reported methodology is scalable and inspires extension to other
allotropes of the graphyne family
Scalable Synthesis and Characterization of Multilayer γ‑Graphyne, New Carbon Crystals with a Small Direct Band Gap
γ-Graphyne
is the most symmetric sp2/sp1 allotrope of carbon,
which can be viewed as graphene uniformly expanded
through the insertion of two-carbon acetylenic units between all the
aromatic rings. To date, synthesis of bulk γ-graphyne has remained
a challenge. We here report the synthesis of multilayer γ-graphyne
through crystallization-assisted irreversible cross-coupling polymerization.
A comprehensive characterization of this new carbon phase is described,
including synchrotron powder X-ray diffraction, electron diffraction,
lateral force microscopy, Raman spectroscopy, infrared spectroscopy,
and cyclic voltammetry. Experiments indicate that γ-graphyne
is a 0.48 eV band gap semiconductor, with a hexagonal a-axis spacing of 6.88 Ã… and an interlayer spacing of 3.48 Ã…,
which is consistent with theoretical predictions. The observed crystal
structure has an aperiodic sheet stacking. The material is thermally
stable up to 240 °C but undergoes transformation at higher temperatures.
While conventional 2D polymerization and reticular chemistry rely
on error correction through reversibility, we demonstrate that a periodic
covalent lattice can be synthesized under purely kinetic control.
The reported methodology is scalable and inspires extension to other
allotropes of the graphyne family