Synthesis of conjugated covalent organic frameworks/graphene composite for supercapacitor electrodes

Abstract

A novel composite with imine-linked covalent organic frameworks on graphene was synthesized in one step with the amine functionalized reduced graphene oxide as the support. The excellent electrochemical properties of this composite can be ascribed to the synergistic effect of the introduction of covalent organic frameworks as well-dispersed nanoscale deposits on the conductive graphene surfaces.Driven by environmental problems and the energy crisis, the development of clean and renewable energy storage materials as well as their devices is urgently needed. 1 Among various energy storage devices, rechargeable batteries and electrochemical capacitors (ECs) are regarded typically as a suitable choice to store energy by transforming chemical energy into electrical energy. 2 Electrochemical capacitors, also called supercapacitors, which store energy using either ion adsorption or fast surface redox reactions, are supposed to be promising candidates for alternative electrical energy storage devices due to their high power density, exceptional cycle life, and low maintenance cost. 3 The performance of supercapacitors is highly dependent on the properties of electrode materials. Many materials have been investigated as the electrode materials in supercapacitors, including carbonaceous materials, transition metal oxides and conducting polymers. 4 Each type of electrode material has its pros and cons. The novel electrode materials with terric performance should be developed.Covalent organic frameworks (COFs) are a novel class of crystalline organic materials with well-dened and predictable two-or-three-dimensional pore structures assembled from molecular building blocks. 5 Their crystal structures are entirely held by strong bonds solely from light elements (B, C, N, H, and O) to form rigid porous architectures. These materials have exceptional thermal stabilities, and low densities, and permanent porosity with high specic surface areas. Their extraordinary and versatile properties have offered the COF materials superior potential in diverse applications, such as gas storage, 6 adsorption, 7 optoelectricity, 8 catalysis, 9 and biosensor. 10 As we know, many COFs have an extended p-conjugated system and inherent nanopores, which may hold promise for fundamental advances in supercapacitor electrode materials. 11 While, COFs has been scarcely reported as electrode materials for supercapacitors, which may be due to the limited chemical and oxidative stability of established COFs linkages precludes this applications.Since the rst report of graphene synthesized in 2004, it has emerged as one of the most active research elds. 12 Due to its fascinating properties, graphene is considered as a highly desirable support for many applications. 13 Here, we present a simple method to fabricate the COFs/graphene composite through the reaction of aldehyde group in 1,3,5-triformylbenzene and amine group in NH 2 -graphene and 1,4diaminobenzene in one step on the surface of amino functionalized graphene. The synthesized conjugated cova...

Covalent organic frameworks based on Schiff-base chemistry: synthesis, properties and potential applications

“…22). 170 The layered NH 2 -rGO and the spherical COFs can be observed in the SEM images of synthesized COFs/NH 2 -rGO. The spherical COFs were anchored tightly on the graphene sheets, which is ascribed to the reaction of the aldehyde group in 1,3,5-triformylbenzene and the amine group in NH 2 -rGO.…”

Porous Polymers as Multifunctional Material Platforms toward Task‐Specific Applications

“…Incorporation of conductive networks in porous polymers is a feasible approach. For example, imine‐linked COFs are grown on the surface of conductive carbon nanotubes, graphene, and nickel nanowires (Figure e,f) . Conductive polymers such as poly(3,4‐ethylenedioxythiophene) (PEDOT) obtained via electropolymerization within the pore of redox‐active 2D COF also permits the quantitative electrochemical accessibility of their redox‐active groups .…”

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

“…Graphene played an important role in fabricating COFs composite materials for electrode materials. Wang and co‐workers fabricated the COFs/NH 2 ‐rGO composite via a simple solvothermal route for supercapacitor electrodes in 2015 by the reaction of 1,3,5‐triformylbenzene with 1,4‐diaminobenzene and amine modified reduced graphene oxide (NH 2 ‐rGO) . Through this process, COFs/NH 2 ‐rGO was obtained in one step successfully with NH 2 ‐rGO and COFs connected by covalent bonds (Figure ).…”

“…Wang and coworkers fabricated the COFs/NH 2 -rGO composite via a simple solvothermal route for supercapacitor electrodes in 2015 by the reaction of 1,3,5-triformylbenzene with 1,4-diaminobenzene and amine modified reduced graphene oxide (NH 2 -rGO). [85] Through this process, COFs/NH 2 -rGO was obtained in one step successfully with NH 2 -rGO and COFs connected by covalent bonds (Figure 10). At the same time, they also prepared the COFs materials by the condensation of 1,3,5-triformylbenzene and 1,4-diaminobenzene with the same method for comparison with COFs/NH 2 -rGO composite as electrode material.…”