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Abstract Single‐atom catalysts show great promise as non‐precious electrocatalysts for CO 2 electroreduction reaction (CO 2 ER). However, it is still challenging to gain a fundamental understanding of the complicated dynamic behavior of CO 2 activation to achieve high product selectivity. Herein, the authors report an unusual iron single‐atom catalyst, containing atomically dispersed Fe–N 4 species and Fe 3 C nanoparticles (NPs) (Fe 3 C|Fe 1 N 4 ). Having a fragmental‐rock‐shaped nanocarbon architecture, isolated Fe–N 4 sites uniformly disperse with adjacent Fe 3 C NPs (<30 nm) in a carbon matrix. Benefiting from the strong coupling effect between Fe 3 C and Fe 1 N 4 and unique spatial nanostructure, Fe 3 C|Fe 1 N 4 displays exceptional CO 2 ER activity with a low onset potential of −0.3 V and high Faradaic efficiency of 94.6% at −0.5 V for CO production, acting as one of the most active Fe–N–C catalysts and even exceeding most other carbon supported non‐precious metal NPs. Experimental observations discover that the excellent CO 2 ER activity of Fe 3 C|Fe 1 N 4 catalyst is attributable to the presence of Fe 3 C NPs that optimizes J CO of the coexisted Fe–N 4 active sites. In situ attenuated total reflectance‐Fourier transform infrared analysis and theoretical calculations reveal that the Fe 3 C NPs strengthen the adsorption of CO 2 on the isolated Fe–N 4 sites to accelerate the formation of *COOH intermediate, and hence enhance the whole CO 2 ER performance.
Chen et al. (Sun,) studied this question.