PdCu alloy nanoparticles with controlled surface phases for efficient and durable hydrogen oxidation in anion exchange membrane fuel cells

Anion Exchange Membrane Fuel Cells (AEMFC) have the potential to significantly reduce the cost of fuel cell technology by employing a very low content of precious metals in the anode and cathode catalysts. Pd-based anodes are well known as promising alternatives to state-of-the-art PtRu electrocatalysts, thanks to their ability to form alloys with non-precious metals such as copper. PdCu alloy nanoparticles (NPs) have been extensively investigated to tailor their crystalline structure and enhance their catalytic activity across a broad range of electrochemical reactions. In this study, PdCu NPs were synthesized via a metal vapor synthesis (MVS) method, and their crystalline structure was modified through annealing at 500 °C under an H2/N2 atmosphere leading to the partial transformation from FCC to BCC surface, resulting in enhanced HOR activity and stability. Here, the correlation between the structural properties of PdCu catalysts and their HOR performance was comprehensively investigated by means of in operando electrochemical X-ray absorption spectroscopy (XAS) under applied potential. In addition, long-term durability tests in AEMFCs under intermittent operation, extending up to three days, were carried out to elucidate the structure–stability relationship governing catalyst performance and to benchmark the obtained results against previously reported Pd-based systems in the literature.