Single-Crystalline Ionic ZIF-8 Derived Long Ni─N Bonded Ni─N─C Configuration for Efficient Electroreduction of CO2 to CO

N-doped carbon-supported single-atom metal sites (Me−N−C) have emerged as promising candidates for electrochemical CO 2 reduction reaction (CO 2 RR) under industrial current densities. However, rationalizing their local coordination environment remains challenging. Herein, a feasible strategy is demonstrated for constructing robust Ni─N─C centers by designing a new family of single-crystalline ionic ZIF-8 materials with atomically defined ionic liquid (IL) cations inside the microchannels. The ─COOH tethered ionic ZIF-8 directed the formation of atomically dispersed Ni─N 4 sites with an elongated Ni─N bond of 1.94 Å. The resulting Ni─N─C catalyst effectively catalyzed the electrochemical CO 2 reduction to CO, delivering a partial current density of 679 mA cm −2 with a Faradic efficiency of 97% and achieving a maximum turnover frequency of 106197 h −1 . The extended Ni─N bond enables the slightly reduced valence state of the Ni site, optimizing the affinity toward CO 2 and intermediate, and thus lowering the energy barrier in the rate-determining * CO 2 → * COOH step.