Fuel Electrode Carbon Corrosion in High Temperature Polymer Electrolyte Fuel Cells—Crucial or Irrelevant?

Abstract

In this study the cause and effect of fuel electrode carbon corrosion in high temperature polymer electrolyte fuel cells are highlighted for the first time. Here, measurements of the CO2 concentration in the fuel electrode effluent and spatially resolved current mapping suggest that the reverse‐current decay mechanism, which is responsible for the well‐known air electrode carbon corrosion, is not responsible for the observed fuel electrode carbon corrosion. We propose a chemical carbon oxidation mechanism, caused by the alternating exposure of the fuel electrode to hydrogen and air during start‐up/shut‐down cycling. Furthermore, a degradation study was performed which indicates a severe performance decrease, up to 40 %, due to fuel electrode carbon corrosion after 600 start‐up/shut‐down events under reformate conditions.

Anode Aging during PEMFC Start-Up and Shut-Down: H2-Air Fronts vs Voltage Cycles

“…Similar to the cathode catalyst layer, all CV features gradually decrease over the course of SUSD aging. As reported by Engl et al for high temperature phosphoric acid fuel cells, 18 this ECSA-loss can be attributed to the passage of H 2 /air fronts through the anode compartment during SUSD. This change of gas atmosphere effectively results in a step-change of the anode potential from the OCP under H 2 (0 V) to the OCP in air (≈1.05 V in the case of a PEMFC) 24 during shut-down and vice versa during start-up.…”

“…However, Engl et al recently showed that SUSD in high temperature phosphoric acid fuel cells leads to significant amounts of carbon corrosion on the anode, along with a loss of Pt electrochemical surface area (ECSA), a finding which the authors attributed to the change of the anode potential upon switching the gas atmosphere between H 2 and air. 18 To the best of our knowledge, no study apart from our previously published ECS Transaction exists that is mainly focused on the degradation of the anode in low-temperature PEMFC systems. 19 While the performance decay from SUSD-induced anode degradation is rather negligible compared to cathode degradation when high anode loadings are used (≥100 μg Pt cm −2 ), it may start to become significant in future PEMFC systems, for which ultra-low anode loadings (≈25 μg Pt cm −2 ) and the use of more stable graphitized cathode carbon supports are envisaged in combination with system mitigation strategies which restrict the occurrence of H 2 /air front events to room temperature, where cathode carbon support oxidation is strongly suppressed.…”

Influence of thermal treatments on the stability of Pd nanoparticles supported on graphitised ordered mesoporous carbons

“…Moreover, the corrosion is accelerated under abnormal conditions like cell reversal, fuel starvation and sudden current transitions [26]. Recent investigations have also individuated an important corrosion phenomena at the anode side in transient operating conditions of fuel feeding [27]. The corrosion rate of carbon materials increases with their surface area, carbon disordering degree and with a high percentage of labile surface carbon moieties [28,29].…”

Medium Modulated Oxygen Reduction Activity of Fe/Co Active Centre‐engrafted Electrocatalysts

“…[1][2] In addition to their contribution to fundamental research, such studies are also important for developing technologies like fuel cells and metalair batteries. [5][6] Later on, a substantial study on the active center and the reaction mechanism over metal-electrolyte interface has led to significant improvements in the stability and performance of the catalysts. [3][4] Despite their remarkable performance, these catalysts had limited technological implications as their high cost and poor stability posed considerable difficulty.…”

“…[3][4] Despite their remarkable performance, these catalysts had limited technological implications as their high cost and poor stability posed considerable difficulty. [5][6] Later on, a substantial study on the active center and the reaction mechanism over metal-electrolyte interface has led to significant improvements in the stability and performance of the catalysts. Also, several alloys of Pt with non-noble metals like Co, Ni, and Fe, with reduced Pt loading have been demonstrated to show enhanced activity.…”