Functional Groups and Pore Size Distribution Do Matter to Hierarchically Porous Carbons as High-Rate-Performance Supercapacitors

Abstract

A series of nitrogen and oxygen enriched porous carbons are prepared from poly-N-phenylethanolamine (PNPEA) and polyaniline (PANI) conducting polymers through pyrolysis, chemical activation, and oxidation processes. Ar or N 2 -adsorption, FT-IR, and X-ray photoelectron spectroscopy are used to characterize the surface areas, pore volumes, surface chemical compositions, and oxygen and nitrogen content. Mikhail and Brunauer micropore analytical method (MP method) is successfully used to analyze the micropore size distribution of the samples. The electrochemical behaviour of the samples is studied in two-and three-electrode cells. The contribution of pseudocapacitance is confirmed by cyclic voltammetry and galvanostatic tests performed in acidic (H 2 SO 4 ) and basic (KOH) media. The potential drop and the equivalent series resistance value certify that the samples with wide micropore size distribution possess low interface resistances. A sample with a BET surface area of 760 m 2 g -1 , nitrogen content of 3.02 at.%, oxygen content of 16.65 at.%, and a wide micropore size distribution, presents the best performance, reaching a value of 370 F g -1 at 0.5 A g -1 and 248 F g -1 at 30 A g -1 , and maintaining capacitance retention ration of 96% at 1 A g -1 (over 1000 cycles) and 92% at 30 A g -1 (over 10000 cycles), respectively. The results obtained for all the samples agree with correlation among capacitance, functional group, and porosity, which indicates that an appropriate selection of the surface chemistry, a reasonable pore size distribution, and a moderate BET surface area, may be promising to achieve high-rate-performance supercapacitors.

Porous Nitrogen‐Doped Carbons as Effective Catalysts for Oxygen Reduction Reaction Synthesized from Cellulose and Polyamide

“…Moreover, there were three different oxygen species on the surface of samples (Figures d and S4), including −COOH groups (533.15–533.80 eV), C−OH/C−O−C groups (532.31–532.82 eV) and C=O groups (530.77–531.55 eV) . Those oxygen groups are probably able to enhance the wettability and hydrophilicity of the carbon so that the inner part can be fully accessible to the electrolyte …”

Three dimensional metal/N-doped nanoplate carbon catalysts for oxygen reduction, the reason for using a layered nanoreactor

“…Figure 7a shows the cyclic voltammetry curves in Ar-saturated 0.5 M H 2 SO 4 for the metal/N-doped and the metal free N-doped carbon catalysts. The voltammograms are virtually featureless, but with wide curvatures which are attributed to the characteristic changes of reduction/oxidation (redox) states of the surface groups of the catalyst and due to Faradic reaction occurring between the nitrogen atoms of the sample and H + in the electrolyte 9,40–42 . The lack of sharp peaks in the carbon catalyst voltammograms implies the absence of the free metal particles onto the carbon catalyst surfaces 9 , although the CV of the FCNG catalyst reveals a pair of very broad redox peaks centered at ca .…”

Applications of Pyrolytic Polyaniline for Renewable Energy Storage

“…And the PBP/CAs showed high capacitance (497 F g −1 ) in 1 mol L −1 H 2 SO 4 at 1 A g −1 and fabulous cycling stability. The N‐containing functional groups can also provide additional pseudocapacitance through the reversible redox reactions, improving the capacitance performance of the material ,. More narrowly, N−Q within graphite layers enhances the electron charge of carbon materials without faradic activity.…”

“…More narrowly, N−Q within graphite layers enhances the electron charge of carbon materials without faradic activity. The N‐5 and N‐6 functional groups at the edges of graphene offer more active sites and contribute additional redox pseudocapacitance by the following Faraday redox reactions in both acidic and basic electrolytes, as shown by the Reactions (1)–(4), thus augmenting the capacitance performance and the power density of supercapacitors ,. In acidic solutions: …”