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 mu g(pd)(-1), 0.305 mA mu g(pd)(-1), 2.105 mA mu g(Pd)(-1), and 8.53 mA mu g(Pd)(-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 mg(PdperMEA)(-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 mg(PdperMEA)(-1), 404.6 mW mg(PdperMEA)(-1), 490.4 mW mg(PdperMEA)(-1), and 552.4 mW mg(PdperMEA)(-1), respectively, at 80 degrees 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 C-C bond cleavage of C-3 glycerol to C-2 oxalate. (C) 2016 Elsevier B.V. All rights reserved.