Pyrolytic graphite, and glassy carbon

Sugiyama K, Aoki K (1989) Catalytic reactions of bis(l,10-phenanthroline) cuprous complex with hydrogen-peroxide at glassy-carbon and pyrolytic-graphite electrodes. J Electroanal Chem 262(1-2) 211-219... 

The chemical attachment of various kinds of functional groups to the surface of carbonaceous materials, such as graphite, glassy carbon, and pyrolytic graphite metals such as Pt or Ti and... 

The carbon and graphite industry is in a state of considerable flux as new designs, new products and new materials, such as high-strength fibers, glassy carbon and pyrolytic graphite, are continuously being introduced. 

Nagoka and Yoshino (1986) studied the surface properties of electrochemically pre-treated glassy carbon by cyclic voltammetry and adsorption of catechol (1,2-dihydroxybenzene). The authors concluded that adsorption of quinones (on glassy carbon and pyrolytic graphite) depends on an electronic effect such as an electrostatic attraction between the adsorbate and partial surface charges, rather than a specific chemical effect. 

This technique has been applied to the study of the reduction of the Keggin heteropolyanion [PM012O40]3- immobilized at the surface of a BDD electrode in aqueous media with two electrolytes HCIO4 1.0 M and LiC104 0.1 M. In the case of carbon electrodes like Glassy Carbon or Pyrolytic Graphite electrodes, in aqueous acidic media, three reversible waves are observed in the potential range (0.6, 0.2)... 

Selection of the working electrode substrates, such as glassy carbon or pyrolytic graphite. These substrates have insignificant catalytic activity towards fuel cell reactions (e.g., ORR, hydrogen oxidation reaction [HOR], and methanol oxidation), so they will not interfere with the catalytic activity of the targeted catalyst. 

For example, SEM examination of carbon surfaces has shown considerable difference between those of polished glassy carbon (GC) and pyrolytic graphite. The surface of pyrolitic graphite is "pebbled" and uneven (32) while the glassy carbon can be... 

Electrochemical oxidation of natural and synthetic nucleic acids at carbon electrodes pyrolytic graphite [34], paraffin-wax-impregnated spectroscopic graphite [35] and glassy carbon [36, 37] has been studied. It was shown that at pH 4.5 the electrochemical activity of nucleic acids is conditioned by the presence of purine residues in polynucleotide chains. 

The first accounts that seemed to give direct enzyme electrochemistry were the reports concerning a soluble blue Cu oxidase, laccase, which catalyzed the rapid four-electron reduction of dioxygen to water. An efficient electrocatalysis of O2 reduction by adsorbed fungal laccase on pyrolytic graphite, glassy carbon, and C02-treated carbon black electrodes was first described by Tarasevich and co-workers (48). Several control experiments were carried out to verify direct electron transfer from the electrode to the Cu sites of the enzyme. 

The other major electrochemical modification approach has been that in which aromatic diazonium salts in an electrolyte solution are reduced at a diamond electrode this leads to the formation of an aryl radical, which can then attach to the diamond surface [74], This work is based on a series of papers in which the same technique was applied to the surface modification of glassy carbon and highly ordered pyrolytic graphite (HOPG) [75-78]. This approach may also be quite fruitful for tbe covalent modification of diamond surfaces, if the attachment is as robust as it is on glassy carbon surfaces. 

Fig. 2. Raman spectra (T = 300 K) from various sp carbons using Ar-ion laser excitation (a) highly ordered pyrolytic graphite (HOPG), (b) boron-doped pyrolytic graphite (BHOPG), (c) carbon nanoparticles (dia. 20 nm) derived from the pyrolysis of benzene and graphitized at 2820°C, (d) as-synthesized carbon nanoparticles ( 850°C), (e) glassy carbon (after ref. [24]).

Impervious graphites, that is electro-graphites with appropriate resin impregnation are used in cascade-, shell- apd tube-type coolers, condensers, pre-heaters etc. in a wide variety of chemical plants. Similar resistance to corrosion applies to glassy carbon vessels and pyrolytic carbons and graphites. The corrosion resistance to principal chemical agents is given in Table 18.2. 

---