Graphite Electrode Electrochemical Behavior

Electrochemical behavior of disordered Carbon electrodes has been characterised by weight measurements, acid-base tests and cyclic Voltammetry. The GDEs are fabricated by mixing a high purity graphite powder with polyethylene to form an essentially homogenous disk electrode. Polyethylene is added to make the GDEs more pliable and easy to handle. However, it's important to note that PE can also reduce the surface area of the graphite available for permeation. The reason for this is the difference in permeability of gas and liquids. A GDE with 25% PE has a BET Surface Area of 5875 cm2, which is 1900 times higher than their geometric surface areas (see Table S1).

To study their effects on electrochemical performances, both GDEs and those without PE have been subjected a number of electrochemical and chemical pretreatments. This study shows that an oxidative pretreatment can increase the GDEs potential window beyond the value of untreated graphite. Increase in the potential is not only due to increased GDE surface, but also because the GDEs can be characterized using X ray photoelectron-spectroscopy. The XPS spectra show an increase in concentration of the weak and strong acid. As shown in the XPS spectrum, the treatment with oxidants also leads to the formation of hydroquinone/quinone redox species at the electrode surface. The GDEs show a catalytic reaction when L-cysteine is dropped onto them at potentials that are similar to GCE.

The GDEs were tested on bilirubin (BOD), and glucose (GOD). BOD is immobilized via direct electron transport from the electrode into the catalytic core of the proteins, while GOD uses redox-mediator-mediated electrotransfer.

The GDEs are very effective in catalyzing the activity of these protein. These results show that GDEs can intercalate monovalent as well as divalent anions, in agreement with the theoretical calculation of diffusion coefficients (D). The D of the anions on the GDE is estimated by Raman spectroscopy. The G band adjacent to the intercalant is split into two peaks. This splitting indicates the intercalation stage. These findings confirm that the GDEs can be a promising candidate for future real-world applications of electrochemical energy storage devices.

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