Clarifying Atomicity-Activity Relations of Platinum Clusters for Oxygen Reduction Reaction
Platinum clusters (Ptn) serve as electrocatalysts for the oxygen reduction reaction (ORR) with reduced Pt loading, yet precise synthesis and atomic-level structure-activity correlation remain unresolved. This study employs single nanoparticle collision electrochemistry to achieve in-situ electrodeposition of atomically precise Ptn on graphene quantum dot supports, enabling instantaneous measurement of intrinsic ORR activity at the individual cluster level. The combinatorial synthesis and analysis method clarifies atomicity-specific ORR activity, attributed to distinct geometric and electronic structures across cluster sizes. Notably, Ptn with atomicity below 20 exhibits exceptionally high ORR activity due to atom-by-atom arrangement. The work establishes a simple, efficient platform for investigating atomicity-activity relationships of nanoclusters under real reaction conditions, facilitating atomic-level electrocatalyst design. Key findings reference prior benchmarks: Pt12 shows ~2.5-fold higher ORR activity than Pt13 (J Am Chem Soc, 2013, 135: 13089), and size-selected Ptn (n = 3–9) demonstrate enhanced activity (Catal Sci Technol, 2022, 12: 1400). The method circumvents ligand removal challenges that often cause size growth or structural reconstruction, offering a ligand-free electrodeposition route via controlled potential waveforms and precursor concentrations.