The separation of chemical vapor deposited (CVD) graphene from the metallic catalyst it is grown on, followed by a subsequent transfer to a dielectric substrate, is currently the adopted method for device fabrication. Most transfer techniques use a chemical etching method to dissolve the metal catalysts, thus imposing high material cost in large-scale fabrication. Here, we demonstrate a highly efficient, nondestructive electrochemical route for the delamination of CVD graphene film from metal surfaces. The electrochemically delaminated graphene films are continuous over 95% of the surface and exhibit increasingly better electronic quality after several growth cycles on the reused copper catalyst, due to the suppression of quasi-periodical nanoripples induced by copper step edges. The electrochemical delamination process affords the advantages of high efficiency, low-cost recyclability, and minimal use of etching chemicals.

Visible light induced oxidative C-H functionalisation of tertiary amines catalysed by the combination of graphene oxide and Rose Bengal was developed. This reaction avoids the use of stoichiometric amounts of peroxy compounds as terminal oxidants. This reaction is useful for tri-alkyl amines including chiral tertiary amines. Both cyanide and trifluoromethyl nucleophiles were shown to participate in this reaction, providing a-cyano-and a-trifluoromethylated tertiary amines.Graphene oxide (GO), a two-dimensional carbon sheet, is traditionally used as a precursor to prepare graphene. Its unique physical and chemical properties have attracted the attention of chemists due to potential applications in plastic electronics, optical materials, solar cells and biosensors, 1 but its potential as a catalyst in organic transformation remains relatively unexplored. 2,3 The feasibility and potential of GO as catalyst were demonstrated by the seminal work of Bielawski and co-workers on the use of GO for the oxidation of alcohols and hydration of alkynes. 3a Subsequently, RGO was reported to catalyse the hydrogenation of nitrobenzene at room temperature. 3b The use of GO and reduced graphene oxide (RGO) as "carbocatalyst" in organic transformations is a nascent area and should lead to exciting discoveries.On a different note, the use of visible light in organic synthesis has attracted the attention of various synthetic organic chemists recently. 4 The groups of MacMillan, 5 Yoon, 6 and Stephenson 7 have showed the ability of metal-based photosensitizers, such as Ru(bpy) 3 Cl 2 (tris(2,2¢-bipyridine)-ruthenium(II) chloride) (Fig. 1), as photoredox catalysts for organic transformations under visible light irradiation. 8 Organic dyes, which are often Fig. 1 Ruthenium bipyridyl complex and Rose Bengal.used in dye-sensitized solar cells, are considered to be cheaper and easier to modify relative to metal-based photosensitizers, 9 thus they are attractive alternatives as photoredox catalysts. The viability of organic dyes as photoredox catalysts has been demonstrated by several groups. 10 For example, Zeitler et al. reported eosin Y catalysed dehalogenation and enantioselective a-alkylation using a combination of photoredox catalyst and organocatalyst. 10a Fukuzumi reported a selective aerobic bromination catalysed by 9-mesityl-10-methylacridinium perchlorate (Acr + -Mes). 10b We have also demonstrated that Rose Bengal (RB, Fig. 1) was able to photocatalyse a-oxyamination of 1,3-dicarbonyl compounds and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) using visible light. 10c Although GO has been reported as a photocatalyst for hydrogen production from water under UV irradiation, 11 the potential application of GO in synthetic photochemistry has not been explored. Therefore we wish to report the combination of GO and RB which works in synergy to efficiently catalyse the a-functionalisation of tertiary amines in the presence of visible light. The oxidative a-functionalisation of tertiary amines through highly reactive iminium intermedia...

The anodized epitaxial graphene (EG) electrode demonstrates a high level of performance for electrochemical impedance as well as differential pulse voltammetry detection of immobilized DNA and free DNA, respectively, at solid-liquid interfaces. On the anodized EG surface, because of the presence of oxygen functionalities as well as π conjugated domains, the anchoring of the DNA probe can be achieved by either covalent grafting or noncovalent π-π stacking readily. The effect of different binding modes on the sensitivity of the impedimetric sensing was investigated. Equivalent circuit modeling shows that the sensitivity of EG to DNA hybridization is controlled by changes in the resistance of the molecular layer as well as the space charge layer. The linear dynamic detection range of EG for DNA oligonucleotides is in the range of 5.0 × 10(-14) to 1 × 10(-6) M. In addition, with the use of differential pulse voltammetry, single stranded DNA, fully complimentary DNA, as well as single nucleotide polymorphisms can be differentiated on anodized EG by monitoring the oxidation signals of individual nucleotide bases.

No abstract