Abstract:The surface area of a single graphene sheet is 2630 m(2)/g, substantially higher than values derived from BET surface area measurements of activated carbons used in current electrochemical double layer capacitors. Our group has pioneered a new carbon material that we call chemically modified graphene (CMG). CMG materials are made from 1-atom thick sheets of carbon, functionalized as needed, and here we demonstrate in an ultracapacitor cell their performance. Specific capacitances of 135 and 99 F/g in aqueous a… Show more
“…The measurements demonstrate that our supercapacitor possess a specific capacitance as high as 263 F g À 1 (see Supplementary Method). Without the use of any binder or specially prepared current collector, our supercapacitors represent a significant improvement over previously reported carbon nanotube-based supercapacitors (51 F g À 1 ) 39 and are substantially better than those obtained with less reduced RGO NH 2 NH 2 (99 F g À 1 ) 37 , and compares well with the recently reported laser reduced GO supercapacitors 40 .…”
Section: Resultssupporting
confidence: 81%
“…To demonstrate the multifunctionality of the RGO film in a variety of large-scale applications, we have explored the RGO films for supercapacitors. Graphene materials have recently been used in supercapacitor 37,38 devices to replace conventional carbon electrodes and have shown very good performance. Figure 5a schematically illustrates the process flow to use our RGO film for the flexible supercapacitor electrodes.…”
Chemical reduction of graphene oxide can be used to produce large quantities of reduced graphene oxide for potential application in electronics, optoelectronics, composite materials and energy-storage devices. Here we report a highly efficient one-pot reduction of graphene oxide using a sodium-ammonia solution as the reducing agent. The solvated electrons in sodium-ammonia solution can effectively facilitate the de-oxygenation of graphene oxide and the restoration of p-conjugation to produce reduced graphene oxide samples with an oxygen content of 5.6 wt%. Electrical characterization of single reduced graphene oxide flakes demonstrates a high hole mobility of 123 cm 2 Vs À 1 . In addition, we show that the pre-formed graphene oxide thin film can be directly reduced to form reduced graphene oxide film with a combined low sheet resistance (B350 O per square with B80% transmittance). Our study demonstrates a new, low-temperature solution processing approach to high-quality graphene materials with lowest sheet resistance and highest carrier mobility.
“…The measurements demonstrate that our supercapacitor possess a specific capacitance as high as 263 F g À 1 (see Supplementary Method). Without the use of any binder or specially prepared current collector, our supercapacitors represent a significant improvement over previously reported carbon nanotube-based supercapacitors (51 F g À 1 ) 39 and are substantially better than those obtained with less reduced RGO NH 2 NH 2 (99 F g À 1 ) 37 , and compares well with the recently reported laser reduced GO supercapacitors 40 .…”
Section: Resultssupporting
confidence: 81%
“…To demonstrate the multifunctionality of the RGO film in a variety of large-scale applications, we have explored the RGO films for supercapacitors. Graphene materials have recently been used in supercapacitor 37,38 devices to replace conventional carbon electrodes and have shown very good performance. Figure 5a schematically illustrates the process flow to use our RGO film for the flexible supercapacitor electrodes.…”
Chemical reduction of graphene oxide can be used to produce large quantities of reduced graphene oxide for potential application in electronics, optoelectronics, composite materials and energy-storage devices. Here we report a highly efficient one-pot reduction of graphene oxide using a sodium-ammonia solution as the reducing agent. The solvated electrons in sodium-ammonia solution can effectively facilitate the de-oxygenation of graphene oxide and the restoration of p-conjugation to produce reduced graphene oxide samples with an oxygen content of 5.6 wt%. Electrical characterization of single reduced graphene oxide flakes demonstrates a high hole mobility of 123 cm 2 Vs À 1 . In addition, we show that the pre-formed graphene oxide thin film can be directly reduced to form reduced graphene oxide film with a combined low sheet resistance (B350 O per square with B80% transmittance). Our study demonstrates a new, low-temperature solution processing approach to high-quality graphene materials with lowest sheet resistance and highest carrier mobility.
“…interlayer spacing, thickness and morphology of graphene nanosheets) and by incorporation of carbon nanotubes or C 60 molecules, the lithium storage capacity of graphene nanosheets could be increased up to above 700 mAh/g, making them suitable for use in rechargeable lithium ion batteries [19]. The large surface area (2630 m 2 /g for a single graphene sheet) and high electrical conductivity (~ 200 S/m) gave a typical chemically modified graphene good performance in double layer capacitors [20]. A large-area graphene film with high electrical quality was grown on a copper substrate by chemical vapor deposition (CVD), and it was successfully used to fabricate dual-gated field effect transistors, with Al 2 O 3 as the gate dielectric [21].…”
Monolayer graphene exhibits extraordinary properties owing to the unique, regular arrangement of atoms in it. However, graphene is usually modified for specific applications, which introduces disorder. This article presents details of graphene structure, including sp2 hybridization, critical parameters of the unit cell, formation of σ and π bonds, electronic band structure, edge orientations, and the number and stacking order of graphene layers. We also discuss topics related to the creation and configuration of disorders in graphene, such as corrugations, topological defects, vacancies, adatoms and sp3-defects. The effects of these disorders on the electrical, thermal, chemical and mechanical properties of graphene are analyzed subsequently. Finally, we review previous work on the modulation of structural defects in graphene for specific applications.
“…3b) demonstrates that the charge is primarily non-faradic in nature and the contribution of the faradic part might be very little, if it exists at all. 24 The calculated specific capacitance of both working electrodes is plotted against the scan rate as shown in Fig. 3c.…”
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