Choice of Platinum
The choice of platinum for the hydrogen electrode is due to several factors:
- inertness of platinum (it does not corrode).
- the capability of platinum to catalyze the reaction of proton reduction
- a high intrinsic exchange current density for proton reduction on platinum
- excellent reproducibility of the potential (bias of less than 10 μV when two well-made hydrogen electrodes are compared with one another)
The surface of platinum is platinized (i.e., covered with platinum black) to:
- Increase total surface area. This improves reaction kinetics and maximum possible current
- Use a surface material that adsorbs hydrogen well at its interface. This also improves reaction kinetics
Other metals can be used for building electrodes with a similar function such as the palladium-hydrogen electrode.
Read more about this topic: Standard Hydrogen Electrode
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