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Formation of functional groups on an activated carbon material surface using electrochemical oxidation
Carbon 107 (2016) 933e934
Contents lists available at ScienceDirect
Carbon journal homepage: www.elsevier.com/locate/carbon
Tanso 273 abstracts TANSO 2016 (No. 273), 75-82 A CARBON ELECTRODE PREPARED BY DEFLUORINATION FOR USE IN AN ELECTROCHEMICAL CAPACITOR
TANSO 2016 (No. 273), 89-95 CARBON NANOTUBE-TEMPLATE SYNTHESIS OF ARTIFICIAL ONEDIMENSIONAL CONDUCTORS USING CHALCOGEN ELEMENTS
Soshi Shiraishi. Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Japan
Toshihiko Fujimori. Center for Energy and Environmental Science, Shinshu University, Japan and JST, PRESTO, Japan
In this review, the author outlines the electrochemical capacitance properties of carbon materials prepared by the defluorination of fluorocarbon materials, such as polytetrafluoroethylene (PTFE), fluorinated hetero-organics, or graphite fluoride with alkali metals or alkali cationnaphthalene anion radical complexes. The surface area and pore size distribution of the PTFE-based porous carbons prepared through the defluorination technique without any conventional activation can be controlled by optimizing the defluorination conditions. These PTFEbased nanoporous carbons show a better rate performance of the capacitance than do conventional activated carbons due to their developed mesoporous structure which suppresses the ion-sieving effect and accelerates ion adsorption/desorption in the pores even when the electrolyte ion is bulky. Fluorinated hetro-organics can be defluorinated as well as PTFE to provide nitrogen- or boron-doped nanoporous carbons. A lamellar-like carbon material with low specific surface area and a large interlayer spacing, obtained by the defluorination of graphite fluoride, shows a high capacitance that depends on polarization voltage. In conclusion, the defluorination technique produces carbon materials suitable for capacitors, leading to new type of porous carbon electrode.
We review our recent progress on the fabrication of artificial onedimensional (1D) conductors using the carbon nanotube-template method. We demonstrate that carbon nanotubes (CNTs) have the ability to stabilize previously-unobserved 1D crystals of chalcogen elements inside their quasi-1D channels. Most importantly, we found by experiment and theory that 1D sulfur crystals, which consist of monatomic zigzag or linear conformations, exhibit a metallic character inside CNTs. Despite the fact that both sulfur and selenium show similar molecular structures in the bulk phase, selenium forms double-helices inside double-wall CNTs. Our theoretical calculations predict that selenium doublehelices have a very small bandgap energy, compared to that of the bulk selenium chain. We foresee a new branch of fundamental metal-insulator transitions caused by the nanospace, thus paving the way toward future applications of non-metallic sulfur and/or selenium as a conducting nanowire.
TANSO 2016 (No. 273), 83-88 DEVELOPMENT, PRODUCTION AND UTILIZATION OF FUNCTIONAL CARBON MATERIALS USING CHEMICAL ENGINEERING APPROACHES Shin Mukai. Division of Applied Chemistry, Graduate School of Engineering, Hokkaido University, Japan The production of materials involves various mass and heat transfer processes which are usually intertwined in a complicated manner. Therefore how to harmonize such processes often becomes the key for efficient material production. Various mass and heat transfer processes must also be carefully considered in order to efficiently utilize the produced materials. However in many cases, materials are produced or used under conditions in which the mass and heat transfer processes involved are far from a harmonized state. In order to improve efficiency, precise analysis of the involved mass and heat transfer processes is required, as processes which lead to the decrease in efficiency must be clarified first. Considering the fact that chemical engineers are very proficient in such analyses, approaches based on chemical engineering are expected to be very helpful in improving the efficiency of the production and/or utilization of materials. The author has frequently used such approaches to develop or improve processes to produce various functional carbon materials. This article describes how such approaches led to the improvement of the production processes of carbon nanofibers, monolithic carbon gels with a microhoneycomb structure and graphene oxide.
http://dx.doi.org/10.1016/j.carbon.2016.06.090
TANSO 2016 (No. 273), 96-100 FORMATION OF FUNCTIONAL GROUPS ON AN ACTIVATED CARBON MATERIAL SURFACE USING ELECTROCHEMICAL OXIDATION Takuya Yura a, Kiyoharu Nakagawa a, b, Hirokazu Kei Kato a, Oda a, b. a Department of Chemical Engineering, Kansai University, Japan; b High Technology Research Core (HRC), Kansai University, Japan We discuss the control of functional groups on an activated carbon surface using electrochemical oxidation. As a result, this method could introduce surface functional groups into activated carbon without a major change of the pore structure. Carboxyl groups were introduced under strong oxidation conditions and lactone was formed under mild oxidation condition. This electrochemical oxidation method could control the functional groups generated on an activated carbon surface. TANSO 2016 (No. 273), 101-106 A PRIMARY STUDY OF THE CARBON OXIDATION AND OXYGEN EVOLUTION REACTIONS OF SEVERAL CARBON MATERIALS IN A KOH AQUEOUS SOLUTION USING A ROTATING RING DISK ELECTRODE TECHNIQUE Taro Kinumoto, Makoto Eto, Kohei Ono, Miki Matsuoka, Tomoki Tsumura, Masahiro Toyoda. Faculty of Engineering, Applied Chemistry, Oita University, Japan Both the carbon oxidation (COR) and oxygen evolution reactions (OER) for Ketjen black, natural graphite, and vapor grown carbon fibers (VGCF) are investigated in a KOH aqueous solution by using a rotating disk ring electrode. The onset potentials for COR and OER are determined and the reaction kinetics, especially the weight loss rate ascribed to COR, are
Contents lists available at ScienceDirect
Carbon journal homepage: www.elsevier.com/locate/carbon
Tanso 273 abstracts TANSO 2016 (No. 273), 75-82 A CARBON ELECTRODE PREPARED BY DEFLUORINATION FOR USE IN AN ELECTROCHEMICAL CAPACITOR
TANSO 2016 (No. 273), 89-95 CARBON NANOTUBE-TEMPLATE SYNTHESIS OF ARTIFICIAL ONEDIMENSIONAL CONDUCTORS USING CHALCOGEN ELEMENTS
Soshi Shiraishi. Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Japan
Toshihiko Fujimori. Center for Energy and Environmental Science, Shinshu University, Japan and JST, PRESTO, Japan
In this review, the author outlines the electrochemical capacitance properties of carbon materials prepared by the defluorination of fluorocarbon materials, such as polytetrafluoroethylene (PTFE), fluorinated hetero-organics, or graphite fluoride with alkali metals or alkali cationnaphthalene anion radical complexes. The surface area and pore size distribution of the PTFE-based porous carbons prepared through the defluorination technique without any conventional activation can be controlled by optimizing the defluorination conditions. These PTFEbased nanoporous carbons show a better rate performance of the capacitance than do conventional activated carbons due to their developed mesoporous structure which suppresses the ion-sieving effect and accelerates ion adsorption/desorption in the pores even when the electrolyte ion is bulky. Fluorinated hetro-organics can be defluorinated as well as PTFE to provide nitrogen- or boron-doped nanoporous carbons. A lamellar-like carbon material with low specific surface area and a large interlayer spacing, obtained by the defluorination of graphite fluoride, shows a high capacitance that depends on polarization voltage. In conclusion, the defluorination technique produces carbon materials suitable for capacitors, leading to new type of porous carbon electrode.
We review our recent progress on the fabrication of artificial onedimensional (1D) conductors using the carbon nanotube-template method. We demonstrate that carbon nanotubes (CNTs) have the ability to stabilize previously-unobserved 1D crystals of chalcogen elements inside their quasi-1D channels. Most importantly, we found by experiment and theory that 1D sulfur crystals, which consist of monatomic zigzag or linear conformations, exhibit a metallic character inside CNTs. Despite the fact that both sulfur and selenium show similar molecular structures in the bulk phase, selenium forms double-helices inside double-wall CNTs. Our theoretical calculations predict that selenium doublehelices have a very small bandgap energy, compared to that of the bulk selenium chain. We foresee a new branch of fundamental metal-insulator transitions caused by the nanospace, thus paving the way toward future applications of non-metallic sulfur and/or selenium as a conducting nanowire.
TANSO 2016 (No. 273), 83-88 DEVELOPMENT, PRODUCTION AND UTILIZATION OF FUNCTIONAL CARBON MATERIALS USING CHEMICAL ENGINEERING APPROACHES Shin Mukai. Division of Applied Chemistry, Graduate School of Engineering, Hokkaido University, Japan The production of materials involves various mass and heat transfer processes which are usually intertwined in a complicated manner. Therefore how to harmonize such processes often becomes the key for efficient material production. Various mass and heat transfer processes must also be carefully considered in order to efficiently utilize the produced materials. However in many cases, materials are produced or used under conditions in which the mass and heat transfer processes involved are far from a harmonized state. In order to improve efficiency, precise analysis of the involved mass and heat transfer processes is required, as processes which lead to the decrease in efficiency must be clarified first. Considering the fact that chemical engineers are very proficient in such analyses, approaches based on chemical engineering are expected to be very helpful in improving the efficiency of the production and/or utilization of materials. The author has frequently used such approaches to develop or improve processes to produce various functional carbon materials. This article describes how such approaches led to the improvement of the production processes of carbon nanofibers, monolithic carbon gels with a microhoneycomb structure and graphene oxide.
http://dx.doi.org/10.1016/j.carbon.2016.06.090
TANSO 2016 (No. 273), 96-100 FORMATION OF FUNCTIONAL GROUPS ON AN ACTIVATED CARBON MATERIAL SURFACE USING ELECTROCHEMICAL OXIDATION Takuya Yura a, Kiyoharu Nakagawa a, b, Hirokazu Kei Kato a, Oda a, b. a Department of Chemical Engineering, Kansai University, Japan; b High Technology Research Core (HRC), Kansai University, Japan We discuss the control of functional groups on an activated carbon surface using electrochemical oxidation. As a result, this method could introduce surface functional groups into activated carbon without a major change of the pore structure. Carboxyl groups were introduced under strong oxidation conditions and lactone was formed under mild oxidation condition. This electrochemical oxidation method could control the functional groups generated on an activated carbon surface. TANSO 2016 (No. 273), 101-106 A PRIMARY STUDY OF THE CARBON OXIDATION AND OXYGEN EVOLUTION REACTIONS OF SEVERAL CARBON MATERIALS IN A KOH AQUEOUS SOLUTION USING A ROTATING RING DISK ELECTRODE TECHNIQUE Taro Kinumoto, Makoto Eto, Kohei Ono, Miki Matsuoka, Tomoki Tsumura, Masahiro Toyoda. Faculty of Engineering, Applied Chemistry, Oita University, Japan Both the carbon oxidation (COR) and oxygen evolution reactions (OER) for Ketjen black, natural graphite, and vapor grown carbon fibers (VGCF) are investigated in a KOH aqueous solution by using a rotating disk ring electrode. The onset potentials for COR and OER are determined and the reaction kinetics, especially the weight loss rate ascribed to COR, are