Clarifying Atomicity-Activity Relations of Platinum Clusters for Oxygen Reduction Reaction

• • Pt12 clusters exhibit ~2.5-fold higher ORR activity than Pt13 (J Am Chem Soc, 2013, 135: 13089–13095), demonstrating that atomicity—not merely size—governs catalytic performance; this non-linear scaling invalidates linear downsizing strategies and demands atom-by-atom precision in catalyst design. • • Size-selected Ptn (n = 3–9) show enhanced ORR activity (Catal Sci Technol, 2022, 12: 1400–1407), with low-atomicity clusters below 20 atoms achieving extraordinarily high activity due to atom-by-atom arrangement; industrial translation requires sub-nanometer control to capture this regime. • • Conventional ligand-protected cluster synthesis yields complicated mixtures with low yields (Acc Chem Res, 2018, 51: 2456–2464), and ligand removal via calcination causes size growth or structural reconstruction depending on temperature and support (ACS Catal, 2020, 10: 6144–6148), creating a reproducibility bottleneck for commercial electrocatalyst manufacturing. • • Single nanoparticle collision electrochemistry enables in-situ electrodeposition of individual Ptn on graphene quantum dots with instantaneous ORR measurement, bypassing ligand removal and providing intrinsic activity data; this method supports high-throughput screening of atomicity-activity relationships under real reaction conditions.