In general, inert nature of the platinum does not result in contamination, and washing with distilled water post-experimentation is sufficient.
However, contamination can occur over time in the presence of strong acidic or alkaline solutions. In such cases, Piranha solution can be used to clean the contaminated platinum electrode. It is a mixture of sulfuric acid and hydrogen peroxide (1:3).
Another method used to clean the counter electrode is to immerse the electrode in 10% nitric acid solution.