Engineering Atomic Sites via Adjacent Dual-Metal Sub-Nanoclusters for Efficient Oxygen Reduction Reaction and Zn-Air Battery.

N-coordinated transition-metal materials are crucial alternatives to design cost-effective, efficient, and highly durable catalysts for electrocatalytic oxygen reduction reaction. Herein, the synthesis of uniformly distributed Cu-Zn clusters on porous N-doped carbon, which are accompanied by Cu/Zn-Nx single sites, is demonstrated. X-ray absorption fine structure tests reveal the co-existence of M-N (M = Cu or Zn) and M-M bonds in the catalyst. The catalyst shows excellent oxygen reduction reaction (ORR) performance in an alkaline medium with a positive half-wave potential of 0.884 V, a superior kinetic current density of 36.42 mA cm-2 at 0.85 V, and a Tafel slope of 45 mV dec-1 , all of which are among the best-reported results. Furthermore, when employed as an air cathode in Zn-Air battery, it reveals a high open-cycle potential of 1.444 V and a peak power density of 164.3 mW cm-2 . Comprehensive experiments and theoretical calculations approved that the high activity of the catalyst can be attributed to the collaboration of the Cu/Zn-N4 sites with CuZn moieties on N-doped carbons.