PdAg/CNT catalyzed alcohol oxidation reaction for high-performance anion exchange membrane direct alcohol fuel cell (alcohol = methanol, ethanol, ethylene glycol and glycerol)

PdAg supported on carbon nanotubes (PdAg/CNT) with an average particle size of 2.7 nm is prepared by an aqueous phase reduction method for alcohol oxidation reaction in direct alcohol fuel cells. In a half-cell system with three electrodes, the peak mass activity of PdAg/CNT reaches 0.105 mA μgPd−1, 0.305 mA μgPd−1, 2.105 mA μgPd−1, and 8.53 mA μgPd−1 for methanol oxidation reaction, ethanol oxidation reaction, ethylene glycol oxidation reaction, and glycerol oxidation reaction, respectively, in 1 M KOH 0.1 M alcohol electrolyte. These values are higher than the mass activity of Pd/CNT at the same applied potential. With PdAg/CNT (0.5 mgPdperMEA−1) as an anode catalyst, a direct methanol fuel cell, a direct ethanol fuel cell, a direct ethylene glycol fuel cell and a direct glycerol fuel cell achieve peak power densities of 135.1 mW cm−2, 202.3 mW cm−2, 245.2 mW cm−2, and 276.2 mW cm−2, with corresponding peak mass activities of 270.2 mW mgPdperMEA−1, 404.6 mW mgPdperMEA−1, 490.4 mW mgPdperMEA−1, and 552.4 mW mgPdperMEA−1, respectively, at 80 °C and ambient pressure. Ag has shown excellent activity towards aldehyde (formaldehyde, acetaldehyde, and glyoxylate) oxidation, thus, the enhancement in alcohol oxidation on PdAg/CNT is proposed due to Ag’s promotion of intermediate aldehyde oxidation. PdAg/CNT also improves the fuel efficiency of glycerol oxidation by contributing to the CC bond cleavage of C3 glycerol to C2 oxalate.