Relationship between carbon corrosion and positive electrode potential in a proton-exchange membrane fuel cell during start/stop operation

Abstract Fuel starvation during start-up and shut-down processes can adversely affect the performance of proton-exchange membrane fuel cells. In this study, fuel starvation is induced intentionally by supplying hydrogen and air to the negative electrode (anode) side alternately, and the individual electrode potential is measured in situ using a dynamic hydrogen electrode. The positive electrode (cathode) potential is increased to 1.4 V when air/hydrogen boundaries developed on the anode side. The development of a high cathode potential causes oxidation of the carbon support with the amount of CO 2 evolution proportional to the cathode potential above 1.0 V. Above ∼1.2 V, CO and SO 2 are generated electrochemically or chemically and the rate of CO production is higher than that of SO 2 . Although a higher cathode potential is induced irrespective of the cell temperature, oxidation of the carbon support is retarded significantly at low temperatures.