Edge planes of graphite

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

Fig. 7.32 Normalized kinetic currents for Cu complexes adsorbed on the edge-plane of graphite, measured at E° circles) and at —0.150 V vs. NHE squares) plotted vs. E° for each Cu complex. The dotted line is the expected behavior for the kinetic current measured at E1/2. All data measured in 0.020 M NaAcO and 0.020 M AcOH pH 4.8, 0.1 M NaC104 except 2,9-Me2-phen measured in 0.020 M NaAcO and 0.072 M AcOH pH 4.2, 0.1 M NaC104...

It is now generally accepted that the surface chemistry and morphology of the edge planes of graphite play a major role in the chemical and electrochemical reactivity of this material in contact with electrolyte. In order to determine whether there is a correlation between the composition and morphology of the SEI formed on the HOPG and on the real anode in lithium-ion batteries, we... 

A distinct answer has been found, however, with respect to the influence of crystallographic orientation of pyrolytic graphite on the rates of various reactions. It could be shown that the rate of cathodic oxygen reduction at the basal plane of graphite is much lower than at surfaces with edge orientation (Morcos and Yeager, 1970). To the contrary, the rates of simple redox reactions hardly depend on face orientation. 

Shi C, Anson EC. 1990. Catalytic pathways for the electroreduction of oxygen by iron tetra-kis(4-iV-methylpyridyl)porphyrin or iron tetraphenylporphyrin adsorbed on edge plane pyrol3dic graphite electrodes. Inorg Chem 29 4298. 

Since rusticyanin is positively charged (p/=9.1), its electrochemical response should be tested at negatively charged electrodes (namely, edge-plane pyrolitic graphite or glassy carbon electrodes). As a matter of fact, no positive response is obtained at a carbon paste electrode, but in the presence of a promoter such as 4,4/-bipyridyl a sufficiently resolved cyclic voltammetric response is obtained, Figure 37.67... 

Reduction potentials of the S. obliqms His59 Ru(NH3)5-modified protein have been determined by cyclic voltammetry using as electrode the oxidized surface obtained by polishing the edge plane of pyrolytic graphite [137]. The modified protein responds well at the electrode, whereas the native protein requires multi-eharged cations, e.g. Mg or [Cr(NH3)g] as mediators to give satisfactory reversibility. Separate reduction potentials at 1=0.10 M(NaCl) for native S. obliquus plastocyanin (389 mV) and [Ru(NH3)5 (imidazole)]... 

Fig. 2.52 Raw square-wave voltammetry data of azurin immobilized on edge plane pyrolytic graphite electrode (PGE) (pH 4.0, 2.0 mol/L NaCl) at different frequencies with = 0.15 V. Dashed line, forward current. Dotted line, backward current. Solid thick line, net current solid thin line, blank net current (reprinted from [101] with permission)...

Figure 3. Steady state polarization curves in KF-2HF at 90 C O layer plane of pyrolytic graphite, edge plane of pyrolytic graphite...

The pioneering studies of capacitance exhibited by basal and edge planes of carbons by Yeager and coworkers showed abnormal behavior, which led Randin and Yeager [151] to conclude that the space charge characteristics of graphite must be taken into account in examining the electrochemical properties of this material. ... 

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