N-Doped Mesoporous Carbon Sheets/Hollow Carbon Spheres Composite for Supercapacitors

Abstract

Composite carbon materials with multiple morphologies (such as spheres/sheets and spheres/tubes) that combine the merits of both structures have a wide range of applications in electrochemistry, catalysis, energy storage, and so on. Therefore, the development of an efficient and simple method for preparing carbonaceous composite materials is a research hot spot. On the basis of the inhomogeneity of 3-aminophenol/formaldehyde (3-AF) polymerization spheres, the hollow 3-AF spheres were obtained after the dissolution of the internal 3-AF oligomer. The dispersed 3-AF oligomer was reassembled with silicate oligomers on the hard template of Mg­(OH)2 sheets and hollow 3-AF spheres linked by CTAB through electrostatic force. The obtained N-MCS/HCS possessed both sheet and sphere structure, with a high specific surface area and uniform mesoporous distribution. As an electrode material, N-MCS/HCS exhibited a good specific capacity (270 F g–1 at the current density of 1 A g–1) and outstanding cycling life stability (96.3% after 5000 cycles) at a current density of 5 A g–1 and could be used as a new electrode material.

Nitrogen and Phosphorus Co‐doped Nanoporous Carbons from Phosphoprotein/Silica Self‐Assemblies for Energy Storage in Supercapacitors

“…Another observation is that the energy storage capacity of CaSC materials is directly related to the amount of N dopant atoms in them (Table 2). As a relatively higher amount of silica gel in the precursor, a larger amount of N dopant atoms and thus a greater amount of pseudocapacitance and specific capacitance can be achieved in these carbon materials [21–24] . However, the carbon material with a larger amount of N groups has less symmetrical charge‐discharge curves and shows relatively less reversibility during many charge‐discharge cycles.…”

“…This also means that the heteroatom dopants in CaSCs, which stem from casein, can lead to a higher pseudocapacitance or power density in the materials, as previously reported for other related materials. [22][23][24][25] As CaSC-1.0 has larger proportions of pyridinic, pyrrolic and pyridone nitrogen species than the other two materials, these species can be said to have contributed the most to the pseudocapacitive charge storage in these materials.…”

“…As a relatively higher amount of silica gel in the precursor, a larger amount of N dopant atoms and thus a greater amount of pseudocapacitance and specific capacitance can be achieved in these carbon materials. [21][22][23][24] However, the carbon material with a larger amount of N groups has less symmetrical charge-discharge curves and shows relatively less reversibility during many charge-discharge cycles. The pseudocapacitance created as a result of oxidation/ reduction at the heteroatom groups must be responsible for the slight deviation from the symmetrical charge-discharge curves associated with electrical double layer phenomenon.…”

“…[19] This is because, when doped with heteroatoms, such as P and N, porous carbon materials can perform greater Faradic processes over their surfaces via redox reactions at their heteroatom sites. [20][21][22][23][24][25] In other words, the heteroatoms enable the material to accumulate charges at its surfaces via pseudocapacitance. In addition, such materials often have conductive structures that allow charges to tunnel through and undergo storage and release.…”

“…In particular, porous carbons doped with heteroatoms have recently been drawing much attention for charge/energy storage applications since such materials can hold a high amount of charge [19] . This is because, when doped with heteroatoms, such as P and N, porous carbon materials can perform greater Faradic processes over their surfaces via redox reactions at their heteroatom sites [20–25] . In other words, the heteroatoms enable the material to accumulate charges at its surfaces via pseudocapacitance.…”