Effect of graphene flake size on functionalisation: quantifying reaction extent and imaging locus with single Pt atom tags

Abstract

Here, the locus of functionalisation on graphene-related materials and the progress of the reaction is shown to depend strongly on the starting feedstock. Five characteristically different graphite sources were exfoliated...

Graphene‐Based Nucleants for Protein Crystallization

“…These calculations have been used previously to estimate the number of dodecyl chains grafted to five different graphene starting materials. [18] After PEGylation, the D/G band ratio for the XG-PEG sediment fraction (0.03 ± 0.001) obtained from mapping statistical experiments remained similar to the values obtained for the starting material (0.04 ± 0.002) (Figure S2, Supporting Information); there was a slight increase in this ratio for the XG-PEG supernatant fraction (0.06 ± 0.003). The histogram distribution shifted to higher I D /I G ratios and broadened for the supernatant XG-PEG S compared to both the deposit XG-PEG D and the as-received material (Figure S2, Supporting Information), indicating a degree of functionalization.…”

“…The grafting ratio (grafted weight fraction) and grafting stoichiometry (graphitic carbons per chain, C/R) were estimated from analysis of the PEG mass fragments and the accompanying mass loss in the corresponding temperature range following calculations reported previously (see Supporting Information). [18] Grafting ratios of 16.8 and 29.6 wt% were observed for PEGylated XG and FLG, respectively (Table 1); The larger grafting ratio for smaller FLG compared to larger XG flakes follow trends recently described for other reduction reactions on a range of graphene-related materials. [18] The absolute C/R values of 2467 and 1404 for XG and FLG, respectively, are consistent with steric predictions for polymers grafted to nanocarbons.…”

“…[18] Grafting ratios of 16.8 and 29.6 wt% were observed for PEGylated XG and FLG, respectively (Table 1); The larger grafting ratio for smaller FLG compared to larger XG flakes follow trends recently described for other reduction reactions on a range of graphene-related materials. [18] The absolute C/R values of 2467 and 1404 for XG and FLG, respectively, are consistent with steric predictions for polymers grafted to nanocarbons. [19] These grafting trends are in good agreement with quantitative Raman data obtained from the ratios of the defect, D, and graphitic, G, bands from statistical mapping experiments (I D /I G ) (Figure 1C and Table 1).…”

“…The other feedstock was an exfoliated natural graphite (XG), which retains a higher degree of graphite crystallinity but with a moderate degree of exfoliation; the larger, flatter layers may promote the growth of protein crystal facets. Both starting materials were exfoliated using a reductive process, using Coulombic charge to introduce repulsion between anionic "graphenide" layers; [18,19] the charge was then used to initiate polymer grafting reactions on the exposed surfaces. Sodium and naphthalene were used as the reducing agent and transfer reagent, respectively.…”

Platinum deposition on functionalised graphene for corrosion resistant oxygen reduction electrodes

“…25 On the other hand, the Ph-SO 3 H derivative obtained from aryl diazonium functionalisation showed a larger particle size (3.8 ± 1.2 nm). Pt nanoparticle aggregation in this case could be due to a less uniform distribution of functional groups for this reaction compared to reductive functionalisation; 26 this heterogeneity might locate the particles only in highly functionalised areas of the graphene layer. Exfoliated FLG also showed a small particle size but slightly larger (2.6 ± 0.6 nm) than the reductively-functionalised samples, probably due to the absence of specific functional groups able to stabilise the Pt nanoparticles to the same extent, although the discharge process may introduce some oxygen groups in the absence of other reagents.…”