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 CuI is used to assist O2 activation. Because of the thermodynamic barrier to generate CuI, 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 CoII 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 CuII or ZnII. We revealed that the hanging CoII ion can provide an electron to improve O2 binding thermodynamically and dynamically, a function represented by the biological CuI 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 O2 binding and activation. [ABSTRACT FROM AUTHOR]