Palladium phosphide interlayer sandwiched into Pd nanocrystals for enhanced formic acid electrooxidation reaction performance

The formic acid oxidation reaction (FAOR) in direct formic acid fuel cells (DFAFCs) relies heavily on the use of Pd catalysts. To improve the performance of DFAFCs, it is crucial to develop highly active and stable Pd catalysts for FAOR. In this work, we demonstrate a novel approach to enhance the electrocatalytic activity and stability of Pd nanocatalysts by incorporating a palladium phosphide (Pd-P) interlayer. The introduction of the Pd-P interlayer can facilitate electron transfer and enhance the vacancy formation energy of the active Pd sites on the surface of Pd@Pd-P@Pd nanocrystals. As a result, the Pd@Pd-P@Pd catalyst can exhibit exceptional long-term durability, with a mass activity of 4.56 A mg^-1_Pd and a specific activity of 28.06 mA cm⁻² towards FAOR, which are 11.5 and 18.1 times higher than those observed for the commercial Pd/C catalyst, respectively. By leveraging the unique properties of the interlayer in Pd nanocatalysts, this work opens up a promising pathway for enhancing the performance of catalysts in sustainable energy conversion systems.