Highly Efficient Core Shell (Sn@Pt and Sn@PtPdSn) Catalyst for Direct Dimethyl Ether Fuel Cells

Dimethyl ether (DME) has been considered as a promising alternative fuel for direct-feed fuel cells. It has a number of advantages over other prominent fuels, including high energy density, easier storage with respect to hydrogen, lower toxicity and crossover when compared to methanol, and more facile complete oxidation as compared to ethanol. However, electro-oxidation mechanism of the dimethyl ether is poorly understood, hindering development of efficient catalysts. The commonly studied binary PtRu catalyst shows much lower activity in DME than methanol oxidation. Sluggish DME adsorption and high activation barrier for the C-O bond cleavage may be responsible for the slow kinetics. Since palladium is known to facilitate the C-O bond cleavage of ethers, the addition of Pd may enhance the electro-oxidation of DME. In this work, core-shell catalysts (Sn@Pt, Sn@PtSn, and Sn@PtPdSn) were prepared by galvanic replacement reaction, which shows much higher activity, both in aqueous and polymer electrolyte fuel cell, than the state-of-the-art binary (Pt₅₀Ru₅₀/C) and ternary catalyst (Pt₄₆Ru₄₄Pd₁₀/C). Moreover, the onset potential for DME oxidation also shifted 100 mV lower then Pt₅₀Ru₅₀/C. The X-ray diffraction pattern confirmed formation of intermetallic nanoparticles.