Dissolution of Platinum in Acidic Media

Abstract

Platinum dissolves chemically after the formation of oxide in oxygen atmosphere, such as the cathode of polymer electrolyte fuel cells(PEFCs). Considering the platinum depositions in the membrane electrolyte of PEFCs, the solubility of platinum (oxide) in the electrolyte might be one of key issues, in order to improve the durability of PEFCs. In this study, platinum solubility has been determined in acidic medium as a function of temperature, pH, and potential which was controlled with oxygen partial pressure. The solubility was 2.9x10-6mol dm-3 at 23oC in 1mol dm-3 H2SO4 under air, and increased with temperature and with the decrease of pH. The platinum solubility significantly increased with the presence of oxygen. From these results, the dissolution of a platinum oxide in acidic medium would follow an acidic dissolution mechanism.