Palladium–copper electrocatalyst for the promotion of the electrochemical oxidation of polyalcohol fuels in the alkaline direct alcohol fuel cell

Abstract

We demonstrate herein two important features of a Pd87Cu13/C electrocatalyst that indicate it is a more efficient catalyst in alkaline media than Pd/C for the electrochemical oxidation of three polyalcohols: ethylene glycol, propylene glycol, and glycerol. First, we have discovered more efficient behavior in a three electrode electrochemical cell, where the electrochemical oxidation rate of ethylene glycol and propylene glycol was 4 times faster on Pd87Cu13/C than Pd/C. In glycerol, the oxidation rate was 3 times faster in the electrochemical cell. This increase in oxidation rate is due to a combination of the electronic and bifunctional effects. Second, we have found that the Pd87Cu13/C catalyst is also more efficient than Pd/C in an operating alkaline direct liquid fuel cell, although the efficiency gains are smaller than the electrochemical cell. During fuel cell testing, we found that the maximum power density of a propylene glycol fuel cell was 86% greater when the anode catalyst was Pd–Cu/C compared with Pd/C. The maximum power densities of the glycerol and ethylene glycol fuel cells increased by 75% and 32%, respectively. These polyalcohol molecules are of significant interest because they can be made from renewable sources and used to produce power in alkaline direct liquid fuel cells.