Ordinary Pyrolytic Graphite

Zeng, Z.Y., S.L. Gupta, H. Huang, and E.B Yeager (1991). Oxygen reduction on poly (4-vinylpyridine)-modified ordinary pyrolytic graphite electrodes with adsorbed cobalt tetra-sulphonated phthalocyanine in acid solution. J. Appl. Electrochem. 21, 973-981. 

Khene et al. [7] used Ordinary Pyrolytic Graphite (OPG) coated with both as-prepared and activated NiPc, NiPc(OH)4 and polyNi(OH)Pc(OH)4, respectively. At the NiPc(OH)4/OPG electrode oligomers fouled the electrode surface, while with polyNi(OH)Pc(OH)4/OPG higher currents for the oxidation of 4-CP were observed, although with a shift to more positive potentials. As said above, the authors concluded that the activation led to a catalytic O-Ni-O bridged structure of the nickel phthalocyanine films. 

Yu et al. showed that SWCNT forest electrodes could be used to observe direct reversible electrochemistry of proteins HRP and myoglobin, and Gooding et al. obtained reversible voltammetry for the heme-containing peptide microperoxidase MP-11 derived from cyt c. Yu et al. assembled oxidized SWCNTs 20-30 nm in length onto a composite bed of Nafion ionomer and precipitated Fe + hydroxides on ordinary pyrolytic graphite (Figure 13.7). Myoglobin or HRP was covalently attached to the ends... 

FIGURE 12, In situ Mossbauer spectra of a 50% w/w Fe-enriched hydrated ferric oxide precipitated on Shawinigan black high-area carbon in the form of a Teflon-bonded electrode in 4 M KOH at (a) -0.3 V and (b) -1.1 V versus Hg/HgO, OH". Inset Cyclic voltammogram of the same, although nonenriched, material as in (a) in the form of a thin porous Teflon-bonded coating electrode deposited on an ordinary pyrolytic graphite electrode, in 4 M KOH. Scan rate 10 mV s" ... 

SWV—square wave voltammetry CV—cyclic voltammetry PG—ordinary basal plane pyrolytic graphite EPG—edge plane pyrolytic graphite ITO— indium tin ojside. 

Pyrolytic graphite is much more resistant to oxidation than ordinary polycrystalline graphites because the attack by oxygen occurs at the edges of the basal planes, which comprise less of the surface of a piece of pyrolytic graphite. In addition, pyrolytic graphite is essentially impervious to oxygen and, therefore, internal oxidation is minimized. 

---