Researchers from Japan and Switzerland found that 3D porous graphene networks realize qualities like high electrical conductivities, mobilities, large surface areas &mechanical strengths.
Disordered carbons comprise graphene fragments assembled into three-dimensional networks. It has long been debated whether these networks contain positive curvature, as seen in fullerenes, negative curvature, as proposed for the schwarzite structures, or zero curvature, as in ribbons. We present a mesh-based approach to analyse the topology of a set of nanoporous and glassy carbon models that accurately reproduce experimental properties. Although all three topological elements are present, negatively curved structures dominate. At the atomic level, analysis of local environments shows that sp– and sp3-bonded atoms are associated with line defects and screw dislocations that resolve topological complexities such as termination of free edges and stacking of low curvature regions into ribbons. These results provide insight into the synthesis of porous carbon materials, glassy carbon and the graphitisability of carbon materials.
Two-dimensional (2D) materials have been central to the developments of various kinds of potentiality as well as practical applications. Especially, graphene-related materials have become crucial research targets and have proposed fascinated applications on electrical transport1−5, thermal transport6, optical7−12, plasmon13−16, biochemical17−20, filter/sensing21−25 and energy26−33 devices. Those devices successfully exploit the graphene characteristics. Specifically, electronic devices from 2D graphene sheets exhibit promising functionalities such as transistors34−36, flexible and transparent electrodes37 and displays38. These prototype devices have shown that graphene-based electrical devices can indeed be applied to practical applications.
At the same time, however, it has been recognized that the performances in 2D graphene-based devices are sometimes much lower than those of conventional carbon devices, which implies that a single graphene sheet itself cannot cover various kinds of applications. Hence graphene materials are facing big challenges for further developments and expansion of applicational breadths. Recently, three-dimensional (3D) porous graphene network architectures constructed from graphene sheets are receiving focused attentions for expanding graphene applications. Various kinds of 3D porous graphene materials have been created, which includes chemically exfoliation, sol-gel methods, template methods and chemical vapour deposition (CVD) for applications such as supercapacitors39−50, biochemical applications51−53 lithium batteries54−64, electrocatalysts65−74, photodetectors75,76, sensing and filter devices77−86, mechanical applications87−90, water purification91−93, transistors94and plasmonics95. These 3D-graphene based devices have demonstrated high performances beyond 2D-graphene devices.
However, such 3D porous graphene devices often suffer from undesirable phenomena and characteristics caused by their 3D morphology itself. For example, uncontrollable connections of graphene layers may bring about electrical short circuits with leakage currents, preventing fine electrical device control. Moreover, 3D morphology, when non-porous, could hinder mass transport of ions and molecules required for chemical reactions and electrical charge transfers. This is natural, since physical properties, hence applications, of 3D porous graphene devices should strongly depend on the structural morphology and their electronic characters in which 2D graphene is modified. Here we envisage that 3D porous graphene devices for realizing various kinds of graphene based electronic devices are subject to requirements of bi-continuous, monolithic, and highly-crystalline structures with open porosity, which can then realize high electrical conductivities and mobilities, large surface areas, high mechanical strengths, high thermal conductivities and chemical stabilities with well- preserved 2D graphene natures of graphene sheets. Read full article here.
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