Capacitance behavior of ordered mesoporous carbon/Fe2O3 composites: Comparison between 1D cylindrical, 2D hexagonal, and 3D bicontinuous mesostructures

Abstract

A B S T R A C TThe combination of high electronic conductivity, enhanced ionic mobility, and high pore volume make ordered mesoporous carbons promising scaffolds for active energy storage materials. However, mesoporous morphology and structural stability needs to be more thoroughly addressed. In this paper, we demonstrate Fe 2 O 3 impregnation into 1D cylindrical (FDU-15), 2D hexagonal (CMK-3), and 3D bicontinuous (CMK-8) symmetries of mesoporous carbons. We use these materials for a systematic study of the effect of mesoporous architecture on the structure stability, ion mobility, and performance of mesoporous composite electrodes. By optimization of the porous structure, the oxide impregnation enabled relatively high performance: >650 F g À1 of Fe 2 O 3 and >200 F g À1 total capacitance. This work highlights the new considerations of structure degradation in different pore symmetries with active material impregnation and its effect on ion mobility and electrochemical performance in porous scaffold electrodes. The results show that the most commonly used 2D CMK-3 is not suitable as a host material due to its poor structure stability and ion mobility, while the 1D FDU-15 and 3D CMK-8 have their own merits related to framework stability and porous structures.

Metal‐Free Nitrogen‐Doped Mesoporous Carbon for Electroreduction of CO2 to Ethanol

“…This implied that many electrons can be easily transported to the surface of the cylindrical channel of c-NC.T he cylindrical channels were uniformly embedded inside the carbon framework of c-NC, the configurations of which were considered to be highly beneficial for electron transfer compared to the crosslinking matrix of carbon nanorods in i-NC. [21] Furthermore,t he specific surface area of c-NC was only about 60 %ofthat of i-NC based on the BET results.T hus,t he available surface electron density for CO 2 reduction in c-NC should be approximately double of that in i-NC. To shed further light on the origin of the superior electrocatalytic activity of the N-doped mesoporous carbon for CO 2 reduction to ethanol, density functional theory (DFT) calculations were performed to examine the possible conversion pathways (see the Supporting Information for the computational details).…”

Nanostructured Iron Oxide/Hydroxide‐Based Electrode Materials for Supercapacitors

“…Na 2 SO 3 is an exception among the neutral aqueous electrolytes, in which the iron oxide/hydroxide‐based electrodes showed different CV behaviors from those observed in other neutral or alkaline electrolytes. A number of studies have reported the electrochemical properties of iron oxide/hydroxide‐based electrodes in Na 2 SO 3 electrolyte, which could achieve a specific capacitance in the range 100 to 300 F g −1 . For example, a couple of redox peaks were seen in the CV curve of a FeO x electrode in Na 2 SO 3 electrolyte, which were attributed to the redox reactions that involved SO 3 2− , including: …”

Metal‐Free Nitrogen‐Doped Mesoporous Carbon for Electroreduction of CO2 to Ethanol

“…This implied that many electrons can be easily transported to the surface of the cylindrical channel of c‐NC. The cylindrical channels were uniformly embedded inside the carbon framework of c‐NC, the configurations of which were considered to be highly beneficial for electron transfer compared to the crosslinking matrix of carbon nanorods in i‐NC . Furthermore, the specific surface area of c‐NC was only about 60 % of that of i‐NC based on the BET results.…”