Platinum or Carbon as counter electrode material is preferred because both require low maintenance and don’t easily get oxidized or reduced.
Platinum, due to its inertness and electrical conductivity, is found to be one of the best counter-electrode materials. Platinum electrodes are available in different forms such as – mesh, foil, wire, and tip. Based on experimental requirements, different forms of platinum electrodes are employed and a mesh kind of platinum electrode is widely used due to its high surface area and porous nature.
Carbon (graphite rods):
- Graphite rods are more affordable than platinum, have higher corrosion resistance, are chemically inert in a wide range of conditions, and have better electrical conductivity.
- These materials (carbon or graphite) are employed as counter electrodes in screen printed electrodes (SPE) because of their low cost, electrical conductivity, and environmental friendliness.
- Limited potential range compared to platinum.
- Less inert when compared to platinum electrode
- It cannot be used in very acidic and oxidizing environments.
- It has a shorter lifespan.