Electrochemical corrosion of platinum electrode in concentrated sulfuric acid

We report on the electrochemical corrosion of a Pt electrode in strong sulfuric acid. The electrochemical measurements were conducted using a Pt-flag working electrode, Ag/Ag2SO4 reference electrode and Pt counter electrode at 25 °C. The measured cyclic voltammograms significantly changed in the H2SO4 concentration range of 0.5–18 mol dm−3, especially from 14 to 18 mol dm−3. After successive potential sweeps for 15 h in 16 mol dm−3 H2SO4, a weight loss of the Pt-flag electrode was realized. In contrast, a controlled potential electrolysis by cathodic polarization caused a weight gain, which was attributed to sulfur deposition by the H2SO4 reduction. The subsequent anodic polarization produced corrosion of the deposited sulfur. Consequently, the alternating polarization generated platinum corrosion, resulted in the production of platinum and sulfur composite particulates in the solution.