Thermochemical functionalisation of graphenes with minimal framework damage

Abstract

Graphene and graphene nanoplatelets can be functionalised via a gas-phase thermochemical method; the approach is versatile, readily scalable, and avoids the introduction of additional defects by exploiting existing sites.

Understanding and controlling the covalent functionalisation of graphene

“…Adventitious defect groups (usually oxygen-based) remaining from graphene synthesis or exfoliation may be desorbed thermally, generating radicals that can trap an alternative functionality. 34,35 Alternatively, specific defect groups may be coupled to further reagents. Most commonly, carboxylic acids, which may be adventitious or deliberate by-products of oxidation (see below), are subjected to esterification or amidification reactions with alcohols and amines, respectively.…”

“…(a) Comparison of grafting stoichiometries between XPS and TGA, based on reports in which both techniques are used on the same sample, 7,8,14,16,25,32,56 (red line, linear fit; black dashed line, equivalence of TGA and XPS measurements). (b) Molecular weight of grafted moiety versus degree of functionalisation (R/C, left) and grafting stoichiometry (C/R, right) and, categorised by reaction type: organo-radical additions 5,7,8,11,12,14,16,17,57,58 (black, diazonium/carbene/nitrene), halogenation 40,[59][60][61][62] (green), plasma-hydrogenation 63 ( puce), cycloadditions 45,46,56,[64][65][66] (red), reductive functionalisation 21,22,[24][25][26]28,29,32,33,35,67 (blue), thermochemical functionalisation 34 (magenta), and oxidation (orange). Limits for oxidation estimated from typical maximum limiting stoichiometry of C 8 O 4 H 5 from Pei et al 68 between 16 Da (epoxide) and 33 Da (carboxyl), with the lower limit for degree of oxidation from hydroxylation via oxo-graphene.…”

“…67 The first grafted species occlude the local, electronically-preferable, defect-adjacent sites from subsequent functionalisation, likely preventing ordered additions, particularly at higher molecular weights. 25 In the case of reactions that occur at a low concentration of intrinsic defects, without propagation (such as the thermochemical method), the degree of functionalisation depends only on the quality of the graphene, not the size of the grafted species 34 (Fig. 2b).…”

Stabilization of Metal Single Atoms on Carbon and TiO2 Supports for CO2 Hydrogenation: The Importance of Regulating Charge Transfer

“…[ 36 ] The fact that some active sites remain at room temperature represents a great opportunity for the formation of new chemical bonds between carbon boundary atoms and atoms/molecules. Shaffer and co‐workers have used such an approach for the thermochemical organic functionalization of various carbon materials, including carbon nanotubes (CNT), [ 37 ] graphene, [ 38 ] and carbon black (CB). [ 39 ] We selected multi‐walled CNT (220 m 2 g −1 ) as catalyst support since SA observation by high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) on such support is relatively easy.…”

Stereocomplexation of Poly(Lactic Acid)s on Graphite Nanoplatelets: From Functionalized Nanoparticles to Self-assembled Nanostructures

“…The adsorption concentration (mmol g -1 ) was calculated from the mmol of polymer chains adsorbed per gram of framework graphene carbon according to the literature: (Hu et al, 2017)…”