30/06/2026
Enhanced methanol oxidation activity and durability of Pt–Pd alloy nanoclusters synthesised by gas-diffusion electrocrystallisation (GDEx)
Gas-diffusion electrocrystallisation (GDEx) provides an electrified route to synthesise Pt–Pd alloy nanostructures with tunable composition. Here, we synthesised Pt–Pd alloy nanoclusters (NCs) with defined Pt/Pd molar ratios (Pt75–Pd25, Pt50–Pd50, Pt25 Pd75), along with monometallic Pt (Pt100) and Pd (Pd100) NCs. The morphology, structure, and composition of the NCs were characterised by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). TEM revealed that the NCs consist of aggregates of smaller primary nanoparticles (NPs), with both NC and primary NP size increasing with Pd content. XRD and XPS confirmed alloy formation and predominantly metallic character for the Pt–Pd NCs. The electrocatalytic activity of the resulting NCs towards methanol oxidation in acid media was investigated. After anodic activation, the mass activity followed the order Pt50–Pd50 > Pt100 > Pt75–Pd25 > commercial Pt/C > Pt25–Pd75, while the specific activity decreased in the order Pt100 > Pt50–Pd50 > Pt75–Pd25 > Pt25–Pd75 > commercial Pt/C. Pd100 was inactive under these conditions. The Pt–Pd alloy NCs also exhibited enhanced durability, with Pt75–Pd25, Pt50–Pd50, and Pt25–Pd75 retaining 40%, 70%, and 82% of their highest activity after 4000 cycles, respectively, compared with 16% for Pt100. The improved performance is attributed to (i) dynamic changes in the oxidation states of Pt and Pd, leading to an increased fraction of metallic Pt at the catalyst surface, as evidenced by XPS, and (ii) enhanced oxidative removal of CO-derived intermediates and CO2 formation, as demonstrated by in situ FTIR. Overall, GDEx provides a simple and efficient strategy for synthesising Pt–Pd alloy electrocatalysts with high activity and improved stability for direct methanol fuel cells.
