Hollow\nN‑Doped Carbon Spheres with Isolated\nCobalt Single Atomic Sites: Superior Electrocatalysts for Oxygen Reduction

Abstract

The search for a\nlow-cost, ultrastable, and highly efficient non-precious\nmetal catalyst substitute for Pt in the oxygen reduction reaction\n(ORR) is extremely urgent, especially in acidic media. Herein, we\ndevelop a template-assisted pyrolysis (TAP) method to obtain a unique\nCo catalyst with isolated single atomic sites anchored on hollow N-doped\ncarbon spheres (ISAS-Co/HNCS). Both the single sites and the hollow\nsubstrate endow the catalyst with excellent ORR performance. The half-wave\npotential in acidic media approaches that of Pt/C. Experiments and\ndensity functional theory have verified that isolated Co sites are\nthe source for the high ORR activity because they significantly increase\nthe hydrogenation of OH* species. This TAP method is also demonstrated\nto be effective in preparing a series of ISAS-M/HNCS, which provides\nopportunities for discovering new catalysts.