Preparation of Sub-1 nm Pt₃Co Nanoclusters via a Seed-Densification Strategy for Enhanced O₂ Capture in Low-Pt-Loading Fuel Cells

Improving O2 capture efficiency by forming densely distributed sub-1 nm Pt alloy nanoclusters is an effective route to enhance the performance of low-Pt-loading membrane electrode assemblies (MEAs). Herein we report a seed-densification strategy in which, when the same amount of Pt precursor is applied, the denser Co seeds lead to smaller Pt3Co alloy nanocrystals due to there being fewer Pt atoms captured by a single seed. In H2–O2 MEA tests, the mass-transfer-limiting current density of the Pt3Co-0.87 cathode is 6.5% and 29.1% higher than those of Pt3Co-1.49 and Pt3Co-3.47, respectively, and in H2–air supply, the corresponding improving rates reach as high as 20.5% and 74.5%. This improvement is well ascribed to the greatly boosted O2 capture efficiency brought by the ultra-tiny Pt3Co nanoclusters with especially dense dispersion in the catalytic layer.