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Direct methanol fuel cell; PtRu; Durability; Unalloyed Ru
Carbon
Abstract:
The durability of polyol-synthesized PtRu/C as anode electrocatalyst for direct methanol fuel cells (DMFCs) has been studied by conducting a 2020-h life-test of a single cell discharging at a constant current density of 100mAcm−2. Critical fuel cell performance parameters including anode activity, cathode activity and internal resistance are, for the first time, systematically examined at the life-test time of 556, 1093, 1630 and 2020 h. High-resolution transmission electron microscopy and X-ray diffraction (XRD) have also been performed and show that PtRu nanoparticles have agglomerated with the mean particle size increasing from 1.82 to 2.78 nm after the 2020-h life-test. Anode polarization and electrochemical impedance spectroscopy (EIS) show that there exists a stable discharging period where the anode polarization potential is less than 0.363V versus dynamic hydrogen electrode (DHE). When the anode polarization potential exceeds 0.363V versus DHE, the performance of the anode degrades dramatically due to the leaching of the unalloyed Ru as indicated by energy dispersive X-ray spectroscopy (EDS) and XRD. This finding provides clues in developing strategies to operate fuel cells achieving maximum lifetime without noticeable performance lose.
