A comparison of direct methanol fuel cell degradation under different modes of operation

► DMFC degradation under variable load on-off (VLOO) and constant load continuous (CLCO) operation. ► Performance loss in VLOO was higher than that under CLCO. ► A major cause was the higher cathode polarization resulting from methanol crossover under VLOO mode. ► Slower Ru dissolution rate under CLCO than under VLOO mode was found.