Electrolyte-Controlled Oxygen Reduction Reaction Via High-Performance Nanoconfined Pt–N ₄ –C ₈ Assay

The atomically dispersed Pt–N4–C8–X with metal loaded (0 to 10 wt %) and the H2SO4 concentration from 5 to 10 M tunes the structure and intermediate adsorption energetics (*O2, *OOH, *OH, and *O), demonstrating superior acidic ORR activity. Pt–N4–C8–SOOH achieved 36 ± 8 mV and 173 ± 10 mV overpotentials at 10 and 100 mA cm–2, respectively, for 5 M H2SO4, 5 wt % metal loading, exhibiting j0 ≈ 2.05 mA cm–2, Tafel slope (≈72 mV dec–1), 112.8 Ag1– mass activity, and up to 3.1-fold TOF enhancements. Chronoamperometry confirms sustained activity for >200 h with minimal overpotential increase (Δη ≈ 12–18 mV) at 10–100 mA cm–2, while maintaining reproducibility across batches.