Utilizing Activated Carbon Nanopores for Electrochemical Oxidation of Perylene to Redox-Active 3,10-Perylenedione: Application in Electrochemical Capacitor Electrodes.

We demonstrate that nanopores of activated carbon (AC) function as nanoreactors that oxidize perylene (PER) to a redox-active organic compound, 3,10-perylenedione (PERD), without any metal catalysts or organic solvents. PER is first adsorbed on AC in the gas phase, and the PER-adsorbed AC is subjected to electrochemical oxidation in aqueous HSO as the electrolyte. Because gas-phase adsorption is solvent-free, PER is completely adsorbed on AC as long as the amount of PER does not exceed the saturated adsorption capacity of the AC, which enables accurate control of the amount adsorbed.

High utilization efficiencies of alkylbenzokynones hybridized inside the pores of activated carbon for electrochemical capacitor electrodes.

Benzoquinone derivatives (BQDs) are hybridized inside activated carbon (AC) pores gas-phase adsorption to prepare electrochemical capacitor materials. In this study, 2 mmol of BQDs are hybridized with 1 g of AC. The hybridization of alkylbenzoquinones (ABQs) with AC enhances the volumetric capacitances of the hybrids from 117 to 201 F cm at 0.

Metal-Free Homocoupling of Pyrene inside the Pores of Mesoporous Carbons via Electrochemical Oxidation: Application for Electrochemical Capacitors.

A pyrene dimer (PYD) is synthesized by electrochemical oxidation homocoupling of pyrene (PY) inside the pores of MgO-templated mesoporous carbons without any metal catalysts or organic solvents. The resulting MgO-C/PYD hybrids can be used as high-performance aqueous electrochemical capacitor electrodes due to the reversible redox property of PYD and large contact area between the hybridized PYD and conductive carbon surfaces, which enable rapid charge transfer at the large contact interface. In our previous study, PY was considered to polymerize through electrochemical oxidation, and activated carbon with the pore sizes of ∼4 nm was used as a porous carbon substrate.

Synthesis of Polynorbornadiene within the Pores of Activated Carbons: Effects on EDLC and Hydrogen Adsorption Performances.

Norbornadiene (NBD) is adsorbed on activated carbon (AC), and the adsorbed NBD is polymerized within the pores of AC. Two kinds of ACs─AC-2 with only micropores of ∼2 nm and AC-4 with not only micropores but also mesopores below 4 nm─are examined to study the effects of the hybridized polynorbornadiene (PNBD) on the electric double-layer capacitor and hydrogen adsorption performance. Various measurements are performed to determine the form of the hybridized PNBD inside the pores of AC.

Study of the pore structure and size effects on the electrochemical capacitor behaviors of porous carbon/quinone derivative hybrids.

We demonstrate the hybridization of a redox-active quinone derivative, 2,5-dichloro-1,4-benzoquinone (DCBQ), and porous carbons with different pore structures for aqueous electrochemical capacitor electrodes. The hybridization is performed in the gas phase, which enables accurate porous carbon/DCBQ weight ratios. This method is advantageous over conventional liquid phase adsorption, in terms of facile optimization of the porous carbon/DCBQ weight ratio to obtain high-performance aqueous electrochemical capacitor electrodes, dependent on the kind of porous carbons; moreover, complete adsorption in the liquid phase cannot be achieved by the conventional liquid phase adsorption method.

Electrochemical polymerization of pyrene and aniline exclusively inside the pores of activated carbon for high-performance asymmetric electrochemical capacitors.

An asymmetric polymer capacitor was prepared from pyrene (PY), aniline (ANI), and commercially available activated carbon (AC) through a solvent-free preparation. PY and ANI were adsorbed into the AC host material in the gas phase and electrochemically polymerized exclusively inside the AC pores in an aqueous H2SO4 electrolyte (1 M). No volumetric expansion of the AC particles occurred upon the adsorption of monomers and their subsequent polymerizations; thus, the volumetric capacitance was enhanced by the inclusion of pseudocapacitive polypyrene (PPY) and polyaniline (PANI).

Electrochemical synthesis of polyaniline in the micropores of activated carbon for high-performance electrochemical capacitors.

Polyaniline (PANI) was synthesized exclusively inside the micropores of activated carbon (AC). This nanosized PANI was smaller than 2 nm in diameter and allowed for fast redox reactions, exhibiting superior pseudocapacitance in terms of power and energy densities over the electric double layer capacitance generated inside the micropores.

Surface passivation of natural graphite electrode for lithium ion battery by chlorine gas.

Surface lattice defects would act as active sites for electrochemical reduction of propylene carbonate (PC) as a solvent for lithium ion battery. Effect of surface chlorination of natural graphite powder has been investigated to improve charge/discharge characteristics of natural graphite electrode in PC-containing electrolyte solution. Chlorination of natural graphite increases not only surface chlorine but also surface oxygen, both of which would contribute to the decrease in surface lattice defects.