Effect of a nitrogen-doped PtRu/carbon anode catalyst on the durability of a direct methanol fuel cell

Electrochemical performance and durability of PtRu supported on N-doped Vulcan is evaluated as an anode in membrane electrode assembly (MEA) single-cell direct methanol fuel cell (DMFC) studies. This material is compared to two reference materials, an in-house PtRu catalyst supported on undoped Vulcan, prepared under the same conditions as the N-doped material besides doping, and a commercial PtRu/C (JM5000). Durability was tested out to 645 h, with periodic interruption for electrochemical testing. After durability, the MEA with N-doped PtRu/C retained more electrochemically active metal on the anode than the MEAs with commercial PtRu/C and undoped PtRu/C (124 compared to 106 and 82 cm2 anode active area per cm2 geometric surface area, respectively). From cathode CO stripping experiments and SEM-EDS studies, it was determined that the MEA with the undoped PtRu/C anode has twice as much ruthenium crossover as the MEA with the N-doped PtRu/C anode. Overall, the MEA with N-doped PtRu/C demonstrates significantly better methanol:air polarization performance compared to the MEA with undoped PtRu/C, and performs comparably to the MEA made with the commercial PtRu/C. The increase in durability for the MEA with the N-doped anode is attributed to nitrogen doping mitigating both anode metal dissolution and Ru crossover.

► 645 h of MEA durability was performed on a nitrogen-doped PtRu/C anode. ► After durability, the DMFC performance of the N-doped anode is 5X the undoped anode. ► The MEA with nitrogen-doped PtRu/C performed comparably to a commercial PtRu/C. ► Nitrogen doping mitigates metal dissolution and Ru crossover during MEA durability.