Direct dimethyl ether fuel cells with low platinum-group-metal loading at anode: Investigations of operating temperatures and anode Pt/Ru ratios

Abstract

Direct dimethyl ether fuel cell is a promising electricity generator due to its highly theoretical energy density, low toxicity, zero NOx and SOx emission, and low fuel crossover from anode to cathode. So far, tremendous investigations have been mainly focused on the development of highly active anode catalysts; while limited efforts were made on the comprehensive operation optimization, especially for the operating temperature and anode composition. Besides, the recent investigations usually used high Pt group metal loading at anode (>3.7 mgPGM cm−2), which is against the current tendency of decreasing Pt-based metal dosage. Herein, we particularly investigate the effects of operating temperatures and Pt/Ru ratios on the DDMEFC performance in a practical reactor with low anode PGM loading (1 mgPGM cm−2) using saturated DME aqueous solution as anode fuel. At 110 °C, the anode Pt1Ru1/C and Pt2Ru1/C catalysts demonstrate the superior current density of ∼117 mA cm−2 and 145 mA cm−2 at 0.5 V. Particularly, the high Pt/Ru ratios present better maximum power density than low Pt/Ru ratios at low temperatures, e.g. 80 °C, but inversely deliver worse performance at high temperatures. This interesting phenomenon is likely due to the temperature-dependent rate determining step transfer.