Covalent Carbene Functionalization of Graphene: Toward Chemical Band-Gap Manipulation

Abstract

In this work, we employ dibromocarbene (DBC) radicals to covalently functionalize solution exfoliated graphene via the formation of dibromocyclopropyl adducts. This is achieved using a basic aqueous/organic biphasic reaction mixture to decompose the DBC precursor, bromoform, in conjunction with a phase-transfer catalyst to facilitate ylide formation and carbene migration to graphene substrates. DBC-functionalized graphene (DBC-graphene) was characterized using a range of spectroscopic and analytical techniques to confirm the covalent nature of functionalization. Modified optical and electronic properties of DBC-graphene were investigated using UV-vis spectroscopy, analysis of electrical I-V transport properties, and noncontact terahertz time-domain spectroscopy. The implications of carbene functionalization of graphene are considered in the context of scalable radical functionalization methodologies for bulk-scale graphene processing and controlled band-gap manipulation of graphene.

Cyanographene and Graphene Acid: Emerging Derivatives Enabling High-Yield and Selective Functionalization of Graphene

“…, 5.13 S m –1 for a carbene functionalized graphene with 3% F.D. 48 ), further supporting the high quality derivatives obtained from the herein proposed method. CV results also highlight the conductive nature of G-COOH showing very high current response, in antithesis to the insulating nature of starting FG 49 and GO 50 (Figure 4d).…”

Strain Engineering of Adsorbate Self-Assembly on Graphene for Band Gap Tuning

“…n order for the remarkable electronic properties of graphene to be fully exploited, a method for opening a band gap in a controlled way must be developed. The physiand chemisorption of various types of molecules on graphene has been studied extensively, a reason being the possible modifications of graphene's electronic structure to make it applicable for semiconductor-technologies [1][2][3][4][5][6][7][8][9][10][11] . Covalent functionalisation of graphene sheets is expected to result in large changes to the electronic structure as it actively disturbs the sp 2 -backbone [12][13][14][15] .…”

Functionalized Graphene-Based Materials as Innovative Adsorbents of Organic Pollutants: A Concise Overview

“…Within the covalent routes, a functionalizing group, such as thionyl, can replace the hydroxyl groups that form on the graphene surface after oxidation (Cai and Larese-Casanova, 2016). The covalent bonding of dibromocarbene groups results in the re-hybridization of the carbon atoms through the formation of cyclopropyl groups, whose degree of defect in the covalent functional group can be confirmed by the Raman spectroscopy after the functionalization of graphene through carbene (Sainsbury et al, 2016).…”

“…(Cobos et al, 2018;Xue et al, 2018;Wang et al, 2017b;Wang et al, 2016b). Therefore, some disadvantages can also be pinpointed: high investment and syntheses cost, specific reactants may be needed to perform functionalization and certain operational conditions necessary, increasing the consumption of energy and other resources (Mahmoud et al, 2018); extensive reaction time is pointed out by some articles as a considerable obstacle in chemical functionalization, which increases its costs (Sainsbury et al, 2016); covalent functionalization generally is physically irreversible, hence reactants and graphene structures becomes irrecoverable ; despite graphene itself being reported as non-toxic by some works (Lazarevic-Pasti et al, 2018;Mahmoud et al, 2018), functionalized graphene may releases byproducts in the form of gases and ionic species during its synthesis reaction and washing; since their toxicity and harm to human health are not yet entirely known, their disposal in the environment may be treated as a liability (Yang et al, 2013a;Hu and Zhou, 2013); some functionalized graphenes are rather difficult to separate after the adsorptive process, requiring elevated energy consumption and complex operations, such as centrifugation, nanofiltration, decantation and precipitation in large tanks, which demands elevated costs of assembly, operation and maintenance (Yao et al, 2017;Zou et al 2016a), depending on the adsorption nature.…”