We have conducted a series of experiments to explore the surface of the polished pyrolytic graphite ‘edge’ electrode as routinely prepared for use in protein film voltammetry. Our investigations have included nitrogen porosimetry and scanning electron microscopy. The nitrogen adsorption revealed a Brunauer–Emmett–Teller surface area ∼104 times greater than the geometric surface area of the electrode. The pore-size distribution calculated by the Horváth–Kawazoe method showed that 10–18% of the pore volume arises from pores having widths >10 nm and, thus, should be accessible to enzymes, although much of the exposed ‘wall’ surface may be inactive for enzyme binding or electron transfer: for example, it may be mainly basal plane. Scanning electron micrographs of the abraded pyrolytic graphite edge showed differing scales of surface damage caused by the abrasion and the presence of many cracks in the surface where thin platelets had been removed.
Pyrolytic graphite Nitrogen adsorption Surface area Protein film voltammetry Protein electrochemistry Scanning electron microscopy
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The authors wish to acknowledge Mike Jenkins for the use of the scanning electron microscope. This research was supported by grants from the Biotechnology and Biological Sciences Research Council (43/B19096) and the Leverhulme Trust (F/08 699/C).
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