Protonated Graphenes

Hsieh, C.-T., Y.-Y. Liu, and A.K. Roy, Pulse etectrodeposited Pd nanoclusters on graphene-based electrodes for proton exchange membrane fuel cells. Electrochimica Acta, 2012. 64(0) p. 205-210. 

Elemental carbon, whether it is soot, diamond, graphite, buckyballs, or graphene, contains only carbon atoms, each of which has exactly six protons in its nucleus. Lead (Pb) is a metallic element. Lead metal contains only lead atoms, each of which contains exactly 82 protons in its nnclens. Neon gas, familiar in neon lights, contains only neon atoms and each of these has jnst 10 protons in its nucleus. Elements are the bnilding blocks ont of which all matter is constitnted. 

In this chapter, we reviewed the structure-controlled syntheses of CNFs in an attempt to offer better catalyst supports for fuel cell applications. Also, selected carbon nanofibers are used as supports for anode metal catalysts in DMFCs. The catalytic activity and the efficiency of transferring protons to ion-exchange membranes have been examined in half cells and single cells. The effects of the fiber diameter, graphene alignment and porosity on the activity of the CNF-supported catalysts have been examined in detail. 

The authors did not discuss these proposed proton and electron transfer reactions [60], but several of their features are noteworthy (i) quite appropriately, there is a distinction between phenolic or qui-none (>C) and carboxyl groups (-C), in the sense that carbon in the former is within the graphene s aromatic system (ii) the reasons for the absence of charge on the deprotonated carboxyl group (Reaction 5.9) and the presence of charge on the quinone group (Reaction 5.11) require justification and are presumably amenable to experimental verification. 

In the liquid phase the topics of principal concern are adsorption and proton and/or electron transfer across the electric donble layer. Carbon materials are unique in these applications becanse they are insolnble over the entire practical range of pH, are amphoteric, and can exhibit either acidic or basic properties this was illustrated in Fignre 1.10. Furthermore, because of their more or less extensive delocalized k-electron system in the graphene layer, they can either accept or donate electrons. Snch remarkable flexibility offers, on the one hand, a nniqne opportnnity to tailor carbon s properties to specific needs in adsorption, catalysis, and electrocatalysis but, as argued in detail elsewhere [24], it is also responsible for the persistent lack of fundamental nnderstanding in the increasingly important field of carbon electrochemistry, despite the tremendous amount of research and development focused on carbon-based capacitors, batteries, and fnel cells. 

Another method to access aeidie groups on activated carbons is direct potentio-metric titration, but it suffers from very slow exchange equilibria in solution [113] and the lack of definite endpoints. The latter faet reflects the spread of dissociation constants of most surface funetionalities on carbons caused by interactions between neighboring groups and effeets resulting from the limited size of the graphene sheets. Assuming a continuous, rather than discrete, distribution of pK values, Contescu et al. [114] showed that potentiometric titration data could be transformed to proton affinity distribution (PAD) eurves and that the results were in... 

Imran Jafri R, Rajalakshmi N, Ramaprabhu S (2010) Nitrogen doped graphene nanoplatelets as catalyst support for oxygen reduction reaction in proton exchange membrane fuel cell. J Mater Chem 20(34) 7114-7117... 

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