Effect of Chloride on Platinum Dissolution

•10 ppm of chloride significantly enhances Pt dissolution at higher potentials.•35 folds increase of Pt dissolution on addition of 100 ppm of chloride.•Pt dissolves in Ptn+ and PtCl42− below 1.2 V and PtCl62− above 1.2 V.•Electrochemically Pt chloro-complex forms during cathodic scan.•Quantitatively, Pt dissolution has linear dependence with chloride concn.

The effect of chloride (from 10 ppm to 100 ppm) on platinum dissolution during potential cycling in 0.5 M H2SO4 solution at 25 °C is investigated using a channel flow double electrode. The dissolved platinum in the form of Ptn+ or a Pt chloro complex produced at the upstream electrode is reduced at the downstream electrode. The introduction of 10 ppm of chloride does not have a significant effect during potential cycling until 1.05 V in the anodic scan; however, above this potential even 10 ppm of chloride has a prominent effect. Higher chloride concentration has a negligible effect in a lower potential range; however, at a higher potential, the dissolution increases by 35-fold. Dissolution of Pt in the form of Ptn+ and PtCl42− is proposed below 1.2 V and that in the form of PtCl62− is proposed above 1.2 V in the anodic scan. Furthermore, a platinum chloro complex is formed electrochemically during cathodic scan. Quantitative analysis is performed and a linear dependence of platinum dissolution with chloride concentration is observed.