Adapting Synthetic Models of Heme/Cu Sites to Energy-Efficient Electrocatalytic Oxygen Reduction Reaction.

In nature, cytochrome c oxidases catalyze the 4e oxygen reduction reaction (ORR) at the heme/Cu site, in which Cu is used to assist O activation. Because of the thermodynamic barrier to generate Cu , synthetic Fe-porphyrin/Cu complexes usually show moderate electrocatalytic ORR activity. We herein report on a Co-corrole/Co complex 1-Co for energy-efficient electrocatalytic ORR. By hanging a Co ion over Co corrole, 1-Co realizes electrocatalytic 4e ORR with a half-wave potential of 0.89 V versus RHE, which is outstanding among corrole-based electrocatalysts. Notably, 1-Co outperforms Co corrole hanged with Cu or Zn . We revealed that the hanging Co ion can provide an electron to improve O binding thermodynamically and dynamically, a function represented by the biological Cu ion of the heme/Cu site. This work is significant to present a remarkable ORR electrocatalyst and to show the vital role of a second-sphere redox-active metal ion in promoting O binding and activation.