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

Abstract

A pyrene dimer (PYD) is synthesized by electrochemical oxidation via 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. In this study, the MgO-templated carbons have the average pore sizes of 5, 10, and 30 nm, and their large mesopore volumes can accommodate a large amount of PYD for enhancing the capacitance. To develop high-performance electrochemical capacitors, the dependence of the capacitance enhancement and the capacitance retention on the amount of PY and the pore sizes of MgO-templated carbons are studied. It is found that mesopores are necessary for fast charging/discharging, but the capacitance retention and capacitance enhancement decrease with increasing the mesopore sizes and the amount of PY due to the decreased utilization ratio of PY.

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

“…Finally, the CV of the counter electrode was carried out to confirm the elution of BQDs from the working electrode and their subsequent adsorption on the counter electrode. The volumetric current in the voltammograms was calculated from the following equation (for details, see the ESI†): 16,20,23,24 where I g is the gravimetric current ( i.e. , the current per 1 g of AC or AC/BQD hybrids), ρ ex AC is the electrode density of AC ( i.e.…”

Activation-Free Synthesis of Chitin-Derived Porous Carbon: Application for Electrical Energy Storage

“…The following analyses were performed according to the methods reported in our previous works: , X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), N 2 adsorption/desorption, and thermogravimetry (TG) analyses; transmission electron microscopy (TEM) observation. The Brunauer–Emmett–Teller specific surface area ( S BET ) was calculated using a N 2 adsorption isotherm in a P / P 0 range of 0.05–0.20.…”

Simple synthesis of nitrogen-doped zeolite-templated carbon and its use in electric double-layer capacitors

“…In this study, the electrochemical measurements were performed without oxidation, and N-1 and N-2 components were revealed effective to enhance the capacitance through rapid redox reactions with maintaining the high capacitance retention up to 2 A g −1 . The capacitance will be further enhanced by the additional O-doping through electrochemical oxidation or the hybridization with redox active materials such as conductive polymers [36,44] and redox-active organic compounds [16,[45][46][47][48] without decreasing the capacitance retention at high current densities. Therefore, the N-doped ZTC prepared using AN and propylene is a potential electrode material for not only EDLCs but also electrochemical capacitors.…”