Cu-N active site enriched Cu-ATz complex with potential-induced dynamic coordination evolution for oxygen reduction reaction.

Nitrogen-rich 3d-transition metal coordination frameworks are promising noble-metal-free ORR electrocatalysts. We report a tetrazole-based Cu-N complex (Cu-ATz) exhibiting efficient four-electron oxygen reduction, excellent durability, and methanol tolerance. The dynamic evolution of copper coordination lowers the *OOH formation barrier, revealing the structure-activity relationship and guiding the rational design of high-performance M-N electrocatalysts.