Working Electrodes

Solvent and acid resistant working electrodes with either highly polished platinum or gold disc embedded in either polytetrafluoroethylene (PTFE) plastic bodies.

Due to their resistance to oxidation in air or in acid, platinum and gold disc electrodes are widely used in standard cyclic voltammetry electrochemistry cells to investigate the oxidation and reduction potentials of organic and inorganic semiconductors either in solution or in film.

Organic semiconductors such as polymers in solution can be drop-cast onto the disc to form films. Platinum and gold disc electrodes are both easy to use and clean.

Net electrodes and L-shape platinum electrodes of different sizes are also available to our customers upon request. Please contact us for more details.

What is a Working Electrode?

The working electrode is probably the most important component of an electrochemical cell.

The working electrode is where the electrically driven chemical reaction and electron transfer happens.

Platinum, gold, carbon and mercury are the most commonly used materials. Being electrochemically inert and easy to be fabricated into many forms, platinum is often preferred. Gold electrodes are less tolerant to oxidation in the positive potential range, but good to form self-assembled monolayer on its surface while carbon electrodes are more tolerant to more negative potentials. 

Redox Reactions

Redox reactions, also referred to as oxidation-reduction reactions, involve the loss or gain of electrons. The loss of electrons is called oxidation and the gain of the electrons reduction.

Oxidation could happen onto the working electrode if the working electrode of the electrochemical cell is driven to a relatively positive potential to the reference electrode. However, while a negative potential is applied to the working electrode, it will result into a reduction reaction. When the potential reaches to a point where an oxidation or reduction is induced, current starts to flow.

The potential of this point is referred to as the onset oxidation or reduction potential (E_onset), shown below where E_pa is the anodic peak potential, E_pc is the cathodic peak potential and E_1/2 is the half-wave potential [E_1/2 = (E_pa + E_pc)/2].

When the applied potential rises through the half-wave potential, oxidation becomes thermodynamically favourable as the current also continues to increase. The oxidation process, however, becomes limited by rate of diffusion process to the electrode surface, characterised by a drop of the current resembling a duck beak.

The potential sweep of the electrode is then reversed and scanned in the opposite direction until the initial potential is reached. For a chemically reversible charge transfer process, the reversed potential sweep gives the rise of the cathodic peak potential passing the half-wave potential by the  reduction of the electrochemically generated species from the first half sweep.

The reversed potential sweep is mostly associated with a reductive (negative) current.

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