Sn-based atokite alloy nanocatalyst for high-power dimethyl ether fueled low-temperature polymer electrolyte fuel cell

Abstract

Next-generation fuels are defined as those produced from non-food resources. A leading member in this group is dimethyl ether− DME (C2H6O), which is a high-energy, non-toxic gas, produced from a wide range of carbon feedstocks and wastes. We explored the oxidation of DME on a highly active catalyst based on Pt3Pd3Sn2 with an atokite structure in comparison to Pt3Sn and Pd3Sn. Following a comprehensive characterization of the new ternary catalyst by electron microscopy, X-ray diffraction, and photoelectron spectroscopy, the DME anodic reaction was analyzed by electrochemical online mass spectrometry of fuel cell gas emission product and supported by density functional theory (DFT) calculations. Pt3Pd3Sn2 catalyst exhibits optimal binding energy (−0.21 eV) and the lowest activation energy for electrochemical oxidation of DME (48.7 kJ mol−1 at 0.80 V). A few preferred oxidation routes were examined at different potentials corroborating with the identified CO2, formic acid, methanol, and methyl-formate by in-operando online mass spectrometry. Fuel-cell constructed using a Pt3Pd3Sn2/C anode catalyst and commercial Pt/C cathode catalyst, delivered an open circuit voltage of 0.9 V, a peak power density of 220 mW cm−2 at 0.40 V and a gravimetric power density of 135 mW mgpgm−1 at ambient pressure and 80 °C, which exceeded the highest values reported so far for direct DME fuel cells.