Graphene functionalizing doping

Nanoporous carbon materials, including black carbons, functionalized carbon, nanostructured carbon, nanostructured diamond like carbon, graphene, N-doped graphene, hierarchical porous carbonaceous foams... 

The N-doped carbons with a nanotube backbone combine a moderate presence of micropores with the extraordinary effect of nitrogen that gives pseudocapacitance phenomena. The capacitance of the PAN/CNts composite (ca. 100 F/g) definitively exceeds the capacitance of the single components (5-20 F/g). The nitrogen functionalities, with electron donor properties, incorporated into the graphene rings have a great importance in the exceptional capacitance behavior. 

In the beginning, functionalization reactions were applied to fullerenes [1], later to CNTs [4,3], and recently to graphene [5]. Although both functionalization approaches have clear differences, they share the same intrinsic objective the creation of defects or doping within the surface of the carbon nanostructures in order to facilitate the interactions between the matrix and the filler. 

Y. Li, Y. Zhao, H. Cheng, Y. Hu, G. Shi, L. Dai, L. Qu, Nitrogen-Doped Graphene Quantum Dots with Oxygen-Rich Functional Groups. Journal of the American Chemical Society 2012,134,15-18. 

Figure 4.35 (a-c) Schematic description of preparation and optoelectronic transparent electrode utilization of N-doped reduced graphene film, (d) UV-Vis spectrum of the N-doped graphene film, (e) Sheet resistances of hydrazine-untreated and hydrazine-pretreated reduced graphene films as a function of the H /NH ratio during thermal reduction (reprinted from [179] with permission from American Chemical Society). 

Besides graphene sheets tested as CO2 capture materials, the introduction of other active sites onto graphene sheets for high-performance CO2 sorbents was also extensively investigated recently [140-142]. For example, PPy functionalized graphene sheets are employed to fabricate N-doped porous carbons via chemical activation [143]. This type of material shows selective adsorption of CO2 (4.3 mmol g ) over N2 (0.27 mmol g ) at 25 °C. Similarly, the highest CO2 uptake (75 mmol g ) at 11 bar and 25 °C over polyaniline-graphene nanocomposites were reported by Mishra and Ramaprabhu [144]. 

Chandra V, Yu SU, Kim SH,Yoon YS, Kim DY, Kwon AH, Meyyappan M, Kim KS (2012) Highly selective CO2 captirre on N-doped carbon produced by chemical activation of polypyrrole functionalized graphene sheets. Chem Commun 48 735-737... 

Yu L, Pan X, Cao X, Hu P, Bao X. Oxygen reduction reaction mechanism on nitrogen-doped graphene a density functional theory study. J Catal 2011 282 183-90. 

Electropolymerized films of Co(III) tetrakis(4-hydroxyphenyl)porphyrin, doped with ionic liquid (CoPbr-IL/G) functionalized graphene gave O2 electroreduction [90]. l-Butyl-3-melhylimidazolium tetrafluoroborate was used as IL. It is noteworthy that the performance of CoPor-IL/G resulted better than that of cobalt porphyrin alone, in terms of potential required and amount of undesired H2O2. 

Kaplan A, Soifer L, Eliyahu D, Korin E, Bettelheim A. Electrocatalytic activity towards oxygen reduction of electropolymerized cobalt porphyrin doped with ionic-liquid-functionalized graphene. J Electrochem Soc 2015 162 H481-5. 

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