A New Strategy for Accelerating Dynamic Proton Transfer of Electrochemical CO2 Reduction at High Current Densities

Developing single-atom electrocatalysts with high activity and superior selectivity at a wide potential window for CO₂ reduction reaction (CO₂RR) still remains a great challenge. Herein, a porous Ni? N? C catalyst containing atomically dispersed Ni? N₄ sites and nanostructured zirconium oxide (ZrO₂@Ni-NC) synthesized via a post-synthetic coordination coupling carbonization strategy is reported. The as-prepared ZrO₂@Ni-NC exhibits an initial potential of ?0.3 V, maximum CO Faradaic efficiency (F.E.) of 98.6% ± 1.3, and a low Tafel slope of 71.7 mV dec^?1 in electrochemical CO₂RR. In particular, a wide potential window from ?0.7 to ?1.4 V with CO F.E. of above 90% on ZrO₂@Ni-NC far exceeds those of recently developed state-of-the-art CO₂RR electrocatalysts based on Ni? N moieties anchored carbon. In a flow cell, ZrO₂@Ni-NC delivers a current density of 200 mA cm^?2 with a superior CO selectivity of 96.8% at ?1.58 V in a practical scale. A series of designed experiments and structural analyses identify that the isolated Ni? N₄ species act as real active sites to drive the CO₂RR reaction and that the nanostructured ZrO₂ largely accelerates the protonation process of *CO₂^? to *COOH intermediate, thus significantly reducing the energy barrier of this rate-determining step and boosting whole catalytic performance.