Highly Microporous Nitrogen‐doped Carbon Synthesized from Azine‐linked Covalent Organic Framework and its Supercapacitor Function

Abstract

Porous carbons with nitrogen-doped (N-doped) structures are promising materials for advanced energy conversion and storage applications, including supercapacitors and fuel cell catalysts. In this study, microporous N-doped carbon was successfully fabricated through carbonization of covalent organic frameworks (COFs) with an azine-linked two-dimensional molecular network (ACOF1). In the carbonized ACOF1, micropores with diameters smaller than 1 nm are selectively formed, and a high specific surface area (1596 cm g ) is achieved. In addition, the highly porous structure with N-doped sites results in enhancement of the electrochemical capacitance. Detailed investigation for the micropore-forming process reveals that the formation of nitrogen gas during the thermal degradation of the azine bond contributes to the microporous structure formation. Therefore, the present direct carbonization approach using COFs allows the fabrication of microporous heteroatom-doped carbons, based on molecularly designed COFs, toward future electrochemical and energy applications.

A Hollow Microtubular Triazine‐ and Benzobisoxazole‐Based Covalent Organic Framework Presenting Sponge‐Like Shells That Functions as a High‐Performance Supercapacitor

“…Figure a presents the CV curves of the TPT‐DAHQ COF recorded at various scan rates, from 5 to 200 mV s −1 . The CV curves all had rectangular shapes, even when recorded at the highest scan rate of 200 mV s −1 , suggesting capacitive behavior with a high rate performance suitable for use in supercapacitors . The distinct appearance of humps in the rectangular CV curves revealed that the capacitive response was derived from a combination of electric double‐layer capacitance (EDLC) and pseudocapacitance arising from the presence of heteroatoms (i.e., nitrogen and oxygen atoms) .…”

“…Figure b provides galvanostatic charge‐discharge (GCD) curves of the TPT‐DAHQ COF recorded at various current densities, from 0.5 to 20 A g −1 . The GCD curves display triangular shapes with a slight bend, implying the existence of both EDLC and pseudocapacitance arising from heteroatoms (i.e., nitrogen and oxygen atoms) . The specific capacitance was calculated from the GCD curves using equation (S1) as shown in Figure c. The TPT‐DAHQ COF exhibited excellent specific capacitance of 256 F g −1 at current density of 0.5 A g −1 which was decreased to 131 F g −1 when the current density was increased to 20 A g −1 .…”

Covalent Organic Frameworks: A New Class of Porous Organic Frameworks for Supercapacitor Electrodes

“…Kim et al prepared a microporous N-doped carbon by the direct carbonization of an azine-linked covalent organic framework (ACOF1) (Figure 24a). [100] For the carbonized ACOF1, the microporous structure was formed selectively with diameters smaller than 1 nm, and the specific surface area was as high as 1596 m 2 · g À 1 . Moreover, the carbonized ACOF1 showed a higher specific capacitance than the carbonized COF1 (Figure 24b), 234 vs 191 F · g À 1 at the current density of 1 A · g À 1 .…”

“…Kim et al. prepared a microporous N‐doped carbon by the direct carbonization of an azine‐linked covalent organic framework (ACOF1) (Figure a) . For the carbonized ACOF1, the microporous structure was formed selectively with diameters smaller than 1 nm, and the specific surface area was as high as 1596 m 2 ⋅ g −1 .…”

New and Advanced Porous Carbon Materials in Fine Chemical Synthesis. Emerging Precursors of Porous Carbons

“…The material was composed of amorphous carbon with micropores on the shell frame and with specific surface areas as high as 525 m 2 /g. Kim et al [84] successfully synthesized microporous N-doped carbons by the direct carbonization of an azine-linked two-dimensional molecular network. The carbonized COF presented high specific surface area (1596 m 2 /g), uniform micropores (less than 1 nm), and N-doped graphitic carbon structure.…”