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

Abstract

Abstract Developing single‐atom electrocatalysts with high activity and superior selectivity at a wide potential window for CO 2 reduction reaction (CO 2 RR) still remains a great challenge. Herein, a porous NiNC catalyst containing atomically dispersed NiN 4 sites and nanostructured zirconium oxide (ZrO 2 @Ni‐NC) synthesized via a post‐synthetic coordination coupling carbonization strategy is reported. The as‐prepared ZrO 2 @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 CO 2 RR. In particular, a wide potential window from −0.7 to −1.4 V with CO F.E. of above 90% on ZrO 2 @Ni‐NC far exceeds those of recently developed state‐of‐the‐art CO 2 RR electrocatalysts based on NiN moieties anchored carbon. In a flow cell, ZrO 2 @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N 4 species act as real active sites to drive the CO 2 RR reaction and that the nanostructured ZrO 2 largely accelerates the protonation process of *CO 2 − to *COOH intermediate, thus significantly reducing the energy barrier of this rate‐determining step and boosting whole catalytic performance.