Mechano-thermal milling synthesis of atomically dispersed platinum with spin polarization induced by cobalt atoms towards enhanced oxygen reduction reaction

Tuning the local spin configurations of single-atom electrocatalysts holds enormous promise in boosting the oxygen reduction reaction (ORR), but still fills with challenging of lacking efficient means. Herein, a binary-atom catalyst (PtCo-NC) consisting of atomically dispersed Pt and Co on nitrogen doped carbon is rationally designed and synthesized by a mechano-thermal milling method. Theoretical calculations reveal that the introduction of atomically dispersed Co results in spin polarization of adjacent Pt atoms, which optimizes the absorption energy and lowers the energy barrier of the rate-determining step, thus accelerating oxygen catalyzed reaction kinetics for PtCo-NC. As a consequence, the constructed PtCo-NC possesses an outstanding ORR performance with a positive half-wave potential (0.85 V), large kinetic current density (83.3 mA cm−2 at 0.8 V), low Tafel slope (85 mV dec−1) and robust cyclic stability (more than 90% retention after 170 h in alkaline media). As the cathodic catalyst, the zinc-air battery driven by PtCo-NC delivers the maximum power density (204 mW cm−2), excellent rate capacity and remarkable durability. The present work may provide new insight into boosting oxygen reduction reaction activity, leading the exploration toward highly efficient catalysts for renewable energy storage and conversion systems.