Accelerating Proton and Electron Transfer Enables Highly Active Fe─N─C Catalyst for Electrochemical CO2 Reduction.

Atomically dispersed Fe─N─C catalysts display great potential for efficient CO production in the field of electrochemical CO2 reduction (ECR), but still suffer from unsatisfactory activity limited by the slow proton and electron transfer during the ECR process. Here, a superior Fe─N─C electrocatalyst is designed by anchoring the individual FeN4 sites and Fe nanoparticles onto highly conductive carbon nanotubes. The resultant catalyst displays a commendable CO partial current density of 16.01 mA cm−2 with a turnover frequency of 3519.6 h−1 at −0.65 V in an H‐type cell, and also exhibits CO selectivity > 90% under high current density over 120 mA cm−2 in a flow cell. This remarkable activity exceeds a host of previously reported Fe─N─C catalysts. The findings indicate that the carbon nanotube facilitates CO production due to its strong capability of electron transport and charge transfer. In situ spectroscopic analysis, controlled experiments, and theoretical calculations reveal that Fe nanoparticles effectively promote water dissociation and the subsequent protonation step, accelerate the formation of *COOH intermediate, and thus greatly enhance the ECR activity. [ABSTRACT FROM AUTHOR]