SOME STUDIES OF ELECTRODES MADE FROM SINGLE-CRYSTALS OF TTF.TCNQ

Electrodes made from single crystals of tetrathiafulvalenium tetracyanoquinodimethanide (TTF.TCNQ) have been used to study the electrochemistry of the conducting organic salt and to investigate the mechanism of the electrochemical oxidation of glucose oxidase at conducting salt electrodes. The single crystal electrodes exhibit much lower non-Faradaic currents than the corresponding polycrystalline electrodes prepared as sublimed films or as pressed pellets. This leads to much lower background current levels and hence more clearly defined electrochemistry for solution species. Studies of the ac impedance behaviour and the electrochemistry of outer sphere redox species indicate that TTF.TCNQ electrodes behave as conventional metallic electrodes within their stable potential range. Results for the electrochemistry of glucose oxidase at the single crystal electrodes are inconsistent with a simple homogeneous mediation mechanism or with simple heterogeneous redox catalysis. Similarities with results obtained for TTF modified glucose oxidase suggest that the enzyme may undergo direct electrochemistry after modification by hydrophobic interaction with TTF molecules derived from the conducting salt electrode.