Degradation effects at the methanol inlet, outlet and center region of a stack MEA operated in DMFC

A review on durability issues and restoration techniques in long-term operations of direct methanol fuel cells

“…Actually, catalyst nanoparticles undergo sintering and dissolution/re-deposition due to the high electrode potentials of DMFC [14,17e22,72,107]. A number of studies have reported the particle growth phenomena for PtRu anode and Pt cathode catalysts during lifetime operation of DMFC, with a higher extent of growth observed for the cathode Pt crystallites [17,22,46,54,59]. Guo et al [15] studied the durability of the DMFC for 2020 h and observed an increase in size of the catalyst particles both in the anode and in the cathode: coarsening of Pt in the cathode was more serious than in the anode.…”

Investigation of the local catalyst distribution in an aged direct methanol fuel cell MEA by means of differential synchrotron X-ray absorption edge imaging with high energy resolution

“…According to Rolison et al, most of the Ru in the PtRu catalyst at the anode is oxidized, whereas only 25% of Ru is alloyed with Pt [13]. Even though a large amount of oxidized Ru is reduced under DMFC operating conditions, a residue of Ru oxide remains in the anode catalyst [14]. The presence of oxidized Ru has an ambivalent effect: on the one hand, oxidized Ru is known to activate the methanol oxidation reaction [15].…”

“…The presence of oxidized Ru has an ambivalent effect: on the one hand, oxidized Ru is known to activate the methanol oxidation reaction [15]. On the other hand, oxidized Ru is more susceptible to corrosion [9,14]. Dixon et al [14] has shown that the reduction of the oxide phase creates unalloyed Ru, which is assumed to be more prone to dissolution and migration to the cathode side compared to the alloyed Ru.…”

“…On the other hand, oxidized Ru is more susceptible to corrosion [9,14]. Dixon et al [14] has shown that the reduction of the oxide phase creates unalloyed Ru, which is assumed to be more prone to dissolution and migration to the cathode side compared to the alloyed Ru. XAS and EDX measurements revealed the presence of oxidized Ru in the DMFC cathode and Ru precipitates in the membrane.…”

Local degradation analysis of a real long-term operated DMFC stack MEA

“…The degradation is examined by polarization curves, electrode overpotentials, current interruption measurements, methanol stripping voltammograms, cyclic voltammetry and SEM/EDX analysis. An identical stack MEA to that used in this work was examined by Dixon et al [18] to analyze local catalyst degradation using different ex-situ techniques, such as EDX, TEM, XAS, XRD. Hence, this work complements that of Dixon et al by studying the local degradation via various insitu electrochemical techniques and SEM/EDX.…”