Regeneration Strategies for Ruthenium-Poisoned ORR Catalysts in Reformate PEM Fuel Cells

Abstract

PEM fuel cells operating on reformate gases suffer from Ru crossover and its re-deposition in the cathode catalyst layer. Therefore, strategies for regeneration of Ru-poisoned ORR catalysts are needed. Here, we developed a regeneration protocol and tested this for commercial PtRu2/Vulcan, which represents a worst case scenario of Ru-poisoned ORR catalysts due to the high Ru content and good intermixture with Pt. Our protocol consists of two chronoamperometric cycles, namely at 1.4 VRHE for 5 minutes followed by 1.6 VRHE for 100 s. The Ru deletion as a function of the number of regeneration cycles was in-situ monitored by electrochemical CO stripping method. The mass and specific ORR activities of the recovered PtRu2/Vulcan increase by 6-times and 4.4-times, respectively. Very remarkably, our regeneration protocol aims to trigger the Ru dissolution by forming the RuO4 during the OER without a negative impact on the catalytic ORR properties of Pt.