Acceptor-type graphite

Hoffman, D. M., R. E. Heinz, G. L. Doll, and P. C. Eklund. 1985. Optical reflectance study of the electronic structure of acceptor-type graphite intercalation compounds. Phys. Rev. B 32 1278-1288. 

However, it is also possible to cycle CM made from pyrolyzed polyacrylonitrile in aqueous electrolytes, according to Beck and Zahedi [378]. Figure 30 shows relatively flat redox peaks around the quinone/hydroquinone center (f/s — 0 V, about 0.7 V vs. SHE). Protons are the counterions in this case. A polyquinonimine structure is concluded from (electro)chemical and FTIR data (cf. Fig. 34). These acceptor-type compounds have relatively high specific capacities of about 300 Ah/kg in the steady state. The initial capacities are even higher. It should be mentioned that graphite nanotubules were synthesized in the nanopores of a porous AI2O3 matrix at 250/ 600 °C [433]. 

The electronic conductivity of residue compounds is several times higher than that of the parent graphite, but still below the conductivity of either donor- or acceptor-type lamellar compounds. Thus conductivity is a sensitive probe for the reversibility of an intercalation reaction. 

The addition of various Kolbe radicals generated from acetic acid, monochloro-acetic acid, trichloroacetic acid, oxalic acid, methyl adipate and methyl glutarate to acceptors such as ethylene, propylene, fluoroolefins and dimethyl maleate is reported in ref. [213]. Also the influence of reaction conditions (current density, olefin-type, olefin concentration) on the product yield and product ratios is individually discussed therein. The mechanism of the addition to ethylene is deduced from the results of adsorption and rotating ring disc studies. The findings demonstrate that the Kolbe radicals react in the surface layer with adsorbed ethylene [229]. In the oxidation of acetate in the presence of 1-octene at platinum and graphite anodes, products that originate from intermediate radicals and cations are observed [230]. 

Furthermore, we believe that the stabilizing influence of boron in the structure of graphite is connected with enhancement of its acceptor properties, which manifest themselves when Boron atoms substitute carbon atoms in the crystalline structure (hexagon ring) of carbon. Such effects are mentioned in the literature for some types of carbon materials [3] and the influence of boron on TEG can be the similar. 

It forms both types of intercalation compounds, donor (D) and acceptor (A) type. This is quite in contrast to most of the other inorganic host lattice such as, for example, TiSa [31], VaOg, CrgOg, MnOa, C0O2, and many others [29], where D-type compounds, mostly with Li+, are absolutely preferred The reason for this is that graphite is a metal, with a Fermi potential of about —0.2 V vs. SHE (see... 

Metal chloride intercalate compounds such as graphite-FeQa, ZnCl2, BeCl2, ZrCU, NbCls, and TaCls are all Friedel-Crafts catalysts, and their action has been well described. The mechanism of formation of graphite acceptor compounds of this type is of interest in that electrons are removed from graphite to form negative ions the neutral molecules formed at the same time diffuse into the lattice. 

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