Nickel–copper supported on a carbon black hydrogen oxidation catalyst integrated into an anion-exchange membrane fuel cell
This work introduces the first practical platinum group metal-free (PGM-free) electrocatalyst for hydrogen oxidation reaction (HOR) in alkaline membrane fuel cells (AMFC), based on nickel-rich Ni 95 Cu 5 -alloy nanoparticles supported on Ketjenblack (KB) family carbon blacks. The catalyst synthesis is scalable and results in expected true alloy of NiCu, which is thoroughly characterized by XRD, microscopy and XPS. Reactivity of the catalyst towards HOR is studied by cyclic voltammetry and explained in view of its composition and structure. This catalyst showed highest specific activity compared to previously reported NiCu electrocatalysts and was successfully integrated into an AMFC membrane electrode assembly (MEA) using commercially available state-of-the-art membrane and ionomer. Single MEA fuel cell tests have demonstrated power density of 350 mWcm -2 at 80°C, which sets a technical record for a PGM-free anode in realistic operating conditions. The MEA with NiCu/KB anode catalysts layer were evaluated by in situ nano- and operando micro-X-ray computed tomography (CT) and results suggest that the nickel state in NiCu is hydrophobic in nature, where the NiCu surface may be isostructural with β-Ni(OH) 2 . The hydrophobic nature of electrocatalyst allows for improved water distribution in MEA and overall fuel cell as observed with operando micro X-ray CT.