Gas phase recovery of hydrogen sulfide contaminated polymer electrolyte membrane fuel cells

The effect of hydrogen sulfide (H2S) on the anode of a polymer electrolyte membrane fuel cell (PEMFC) and the gas phase recovery of the contaminated PEMFC using ozone (O-3) were studied. Experiments were performed on fuel cell electrodes both in an aqueous electrolyte and within an operating fuel cell. The ex-situ analyses of a fresh electrode; a H2S contaminated electrode (23 mu molH(2)S cm(-2)): and the contaminated electrode cleaned with O-3 shows that all sulfide can be removed within 900 s at room temperature. Online gas analysis of the recovery process confirms the recovery time required as around 720 s. Similarly, performance studies of an H2S contaminated PEMFC shows that complete rejuvenation occurs following 600-900 s O-3 treatment at room temperature. The cleaning process involves both electrochemical oxidation (facilitated by the high equilibrium potential of the O-3 reduction process) and direct chemical oxidation of the contaminant. The O-3 cleaning process is more efficient than the external polarization of the single cell at 1.6 V. Application of O-3 at room temperature limits the amount of carbon corrosion. Room temperature O-3 treatment of poisoned fuel cell stacks may offer an efficient and quick remediation method to recover otherwise inoperable systems. (C) 2013 The Authors. Published by Elsevier B.V. Open access under CC BY license.