Edge functional groups

G. SILANOL. Phylosilicate tetrahedral -OH edge functional group (see Chapter 4). 

V. Edge-oxidized SWCNTs lose their edge functional groups very quickly, except for edge C-H bonds. The presence of hydrogen on the rim decreases the probability of self-capping, similar as in the prohibitive role of hydrogen in the fullerene formation process in combustion synthesis [19]. 

Fig. 6. Band edge positions of several semiconductors ia contact with an aqueous electrolyte at pH 1 ia relation to the redox (electrode) potential regions (vs the standard hydrogen electrode) for the oxidation of organic functional groups (26,27).

Fig. 5.27 Oxygen functional groups on the edge plane of graphite...

A completely different access to molecules with a scissor-like shape is opened up via spiro-linkage. Typical examples following this building principle are the spiro-bifluorenes 22 3) and 23 43 which differ also in the functional groups. In case of the spirocompounds, the flexible hinge is not applicable-and the edges of the molecular scissors are fixed at an angle of 90°. 

In this paper, we presented new information, which should help in optimising disordered carbon materials for anodes of lithium-ion batteries. We clearly proved that the irreversible capacity is essentially due to the presence of active sites at the surface of carbon, which cause the electrolyte decomposition. A perfect linear relationship was shown between the irreversible capacity and the active surface area, i.e. the area corresponding to the sites located at the edge planes. It definitely proves that the BET specific surface area, which represents the surface area of the basal planes, is not a relevant parameter to explain the irreversible capacity, even if some papers showed some correlation with this parameter for rather low BET surface area carbons. The electrolyte may be decomposed by surface functional groups or by dangling bonds. Coating by a thin layer of pyrolytic carbon allows these sites to be efficiently blocked, without reducing the value of reversible capacity. 

Sorption depends on Sorption Sites. The sorption of alkaline and earth-alkaline cations on expandable three layer clays - smectites (montmorillonites) - can usually be interpreted as stoichiometric exchange of interlayer ions. Heavy metals however are sorbed by surface complex formation to the OH-functional groups of the outer surface (the so-called broken bonds). The non-swellable three-layer silicates, micas such as illite, can usually not exchange their interlayer ions but the outside of these minerals and the weathered crystal edges ("frayed edges") participate in ion exchange reactions. 

Vairavamurthy, A., Maletic, D., Wang, S., Manowitz, B., Eglinton, T., and Lyons, T. (1997). Characterization of sulfur-containing functional groups in sedimentary humic substances by X-ray absorption near-edge spectroscopy. Energy Fuels 11,546-553. 

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