Muchun Liu; Cintia Juliana Castilho; Robert H. Hurt
Abstract
Over the last decade, graphene research has developed into a large and multi-faceted field concerned with the synthesis, structure, properties, and applications of various ultrathin sheet-like carbon forms. This article presents a historical perspective on ultrathin carbons, and on the traditional role ...
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Over the last decade, graphene research has developed into a large and multi-faceted field concerned with the synthesis, structure, properties, and applications of various ultrathin sheet-like carbon forms. This article presents a historical perspective on ultrathin carbons, and on the traditional role of the “graphene layer” as a conceptual model for describing crystalline polymorphs in sp < sup > 2 -based carbon materials. Bulk carbons can often be usefully modelled as physical assemblies of distinct graphene layers whose length, curvature, packing, and orientation determine carbon properties and their observed anisotropy. The article then gives a brief perspective on the emerging subfield of graphene research that uses nanosheets as physical building blocks to assemble new material architectures. In analogy with macroscopic sheets of paper or fabric, graphene nanosheets can be manipulated by stacking, wrapping, folding, wrinkling, or crumpling, to make novel carbons not accessible through traditional routes based on molecular or solid-state precursors. These include aerogels, crumpled particles, encapsulation sacks, and a variety of engineered films structures that can be planar or microtextured. While much work has been done in this graphene subfield, important research opportunities remain. Among these are the creation of hybrid structures involving graphene nanosheets systematically combined with other substances to form graphene-molecular hybrids, graphene-nanoparticle hybrids (2D-0D), graphene-nanofiber hybrids (2D-1D), and nanosheet heterostructures (2D-2D).
Pankaj Chamoli; Malay K. Das; Kamal K. Kar
Abstract
In the present study, temperature dependence reduction of graphene oxide into graphene nanosheets has been demonstrated using green reducing agent, urea. As synthesized graphene nanosheets have been characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy(UV-Vis), ...
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In the present study, temperature dependence reduction of graphene oxide into graphene nanosheets has been demonstrated using green reducing agent, urea. As synthesized graphene nanosheets have been characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy(UV-Vis), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photon spectroscopy (XPS). Raman analysis confirms that the maximum reduction of graphene oxide is observed at 140 o C, and reached to high Raman D to G band intensity ratio of ~ 1.41. FTIR analysis supports the Raman signature of maximum reduction of oxygen functional groups from graphene oxide at 140 o C. XPS analysis validates the Raman and FTIR signature of maximum removal of oxygen species from graphene oxide at 140 o C, and confirms the attainment of the C/O ratio of ~ 5.66. Result indicates that the urea offers excellent reductive ability at high temperature to produce graphene nanosheets.
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