Modular Preparation of Graphene‐Based Functional Architectures through Two‐Step Organic Reactions: Towards High‐Performance Energy Storage

Abstract

Graphene-based materials have recently attracted much attention due to their extraordinary physical and chemical properties, which make them attractive candidates for many technological applications in sensing, optoelectronics, catalysis, and energy storage. Their chemical functionalization is key to tuning their properties. Herein, a novel two-step synthetic approach, which enables a high degree of covalent functionalization of graphene oxide (GO) is devised, thereby making the facile attachment of various robust functional molecules possible. Such a process relies initially on the grafting of an ethylenediamine linker followed by a second step consisting of the condensation reaction between aldehyde and amine groups to form imine bonds. As test beds, two kinds of graphene-based functional systems, namely, porphyrin-modified GO and ferrocene-modified GO, are prepared. Such hybrid systems are characterized by various spectroscopic and microscopic techniques. The degree of functionalization is quantified as the attachment of one porphyrin or ferrocene unit to every 34 or 77 carbon atoms of the GO scaffold, respectively, which is much higher than that of values obtained upon using various established chemical approaches to functionalize GO, such as condensation, cycloaddition, or coupling reactions. For the first time, the reduced form of ferrocene-modified GO was employed as an electrode material in supercapacitors, showing a specific capacitance of 127 F g at a current density of 1 A g , with capacitance retention of about 93 % after 5000 cycles at the same current density; this demonstrates great potential for application in high-performance energy-storage devices.

Supercapacitor electrodes based on metal‐organic compounds from the first transition metal series

“…Among a diversity of MOFs, ultrathin 2D metal‐porphyrin framework (MPF) nanosheets have drawn extensive attention as electrode materials for SCs due to their π‐conjugated skeletons, large surface areas, inherent porosities and abundant accessible active sites 71,92,116,131,132,179‐181,187‐194 . Moreover, porphyrins generally present small HOMO‐LUMO gaps that enable the facile uptake and release of electrons, thus leading to fast redox kinetics 195 .…”

Functionalization of Graphene Oxide with Porphyrins: Synthetic Routes and Biological Applications

“…Within this framework, Zhang et al proposed an effective two-step reaction (Scheme 7). [142] According to the authors: i) the À NH 2 groups of ethylenediamine can mediate the ring opening of epoxy units and react with À CHO groups from GO, thus affording Schiff bases; ii) the condensation of free À NH 2 groups on the ethylenediamine-modified GO with the formyl group of 5-(4formylphenyl)-10,15,20-triphenylporphyrin) (CHO-TPP) provided the required imine bond between both components. Table 4.…”

Composites and Copolymers Containing Redox-Active Molecules and Intrinsically Conducting Polymers as Active Masses for Supercapacitor Electrodes—An Introduction

“…This was attributed to covalent linkages between the copolymer and rGO not proven in the report. More general considerations on graphene functionalized with ferrocene and other organometallic compounds have been reported [91]. A PANI-stabilized composite of ferrocene and graphene has been prepared showing 86% capacitance retention after 5000 cycles [92].…”

“…GO has been functionalized with ferrocene-CHO ( Figure 13) and with porphyrin-CHO [91]. The ferrocene-modified material showed a very wide redox response compared to the welldefined redox-peak pair of molecular ferrocene.…”