New insights into enhanced electrocatalytic performance of carbon supported Pd–Cu catalyst for formic acid oxidation

The direct formic acid fuel cell (DFAFC) has two major shortcomings that limit its lifespan and performance: (i) the poor electrocatalytic stability of the carbon supported Pd (Pd/C) catalyst and (ii) rapid decomposition of formic acid over the Pd/C catalyst. To solve the problems, the carbon-supported Pd–Cu (Pd–Cu/C) catalysts with different atomic ratios of Pd and Cu are successfully prepared with a simple impregnation–reduction method. It is reported for the first time that the electrocatalytic performances of the Pd–Cu/C catalysts for formic acid oxidation are related to the decomposition rate of formic acid over the Pd–Cu/C catalysts. When the content of Cu in the Pd–Cu/C catalysts is gradually increased, the decomposition rate of formic acid over the Pd–Cu/C catalysts is correspondingly decreased, leading to the decrease in the production of poisoned CO. Therefore, the electrocatalytic performances of the Pd–Cu/C catalysts for formic acid oxidation are much better than that of the Pd/C catalyst. However, when the content of Cu in the Pd–Cu/C catalyst is too high, the electrocatalytic performance of the Pd–Cu/C catalyst would be decreased because Cu has no electrocatalytic activity for formic acid oxidation. Based on the above reasons, among all Pd–Cu/C catalysts prepared, the electrocatalytic performance of the Pd–Cu/C catalyst with 3:1 atomic ratio of Pd and Cu for formic acid oxidation is best.

► Pd–Cu/C catalysts with different atomic ratios of Pd and Cu are prepared with simple method.
► All electrocatalytic performances of Pd–Cu/C for formic acid oxidation are better than that of Pd/C.
► It is due to no catalytic performance of Pd–Cu/C for decomposition of formic acid.
► Electrocatalytic performance of the Pd–Cu/C with 3:1 of Pd and Cu is best.