Open circuit voltage mystery solved for proton-conducting fuel cells?

摘要

Hydrogen and oxygen are combined to water by a chain reaction. In proton-conducting fuel cells the electrolyte membrane is placed between the first and the second link. The formation of water is completed by chemical reactions not contributing to the voltage establishment, but only to the thermal balance. Thus the Equilibrium Potential "EP" cannot be based on the overall molecular reaction 2H(2) + O-2 = 2H(2)O yielding an EP of 1.23 V, but another reactions must be considered. Hydrogen radicals are formed by platinum inside the anode chamber. Radicals reappearing at the cathode either recombine to hydrogen molecules or split oxygen molecules and form hydroxyl radicals. Platinum is needed at the cathode to secure a steady supply of hydrogen radicals. Water is obtained by chemical oxidation of hydroxyl radicals. Two EPs are obtained for hydrogen recombination (measurable) and hydrogen partial oxidation (virtual). Also, two polarity change steps must be considered in the EP equation. With these modifications an excellent agreement between theory and experiment is obtained. (C) 2021 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.