(173ag) Promoting Electrochemical CO2 Reduction Via Boosting Activation of Adsorbed Intermediates on Iron Single-Atom Catalyst

Single-atom catalysts show great promise as non-precious electrocatalysts for CO₂ electroreduction reaction (CO₂ER). However, it is still challenging to gain a fundamental understanding of the complicated dynamic behavior of CO₂ activation to achieve high product selectivity. Herein, the authors report an unusual iron single-atom catalyst, containing atomically dispersed Fe–N₄ species and Fe₃C nanoparticles (NPs) (Fe₃C|Fe₁N₄). Having a fragmental-rock-shaped nanocarbon architecture, isolated Fe–N₄ sites uniformly disperse with adjacent Fe₃C NPs (<30 nm) in a carbon matrix. Benefiting from the strong coupling effect between Fe₃C and Fe₁N₄ and unique spatial nanostructure, Fe₃C|Fe₁N₄ displays exceptional CO₂ER 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 CO₂ER activity of Fe₃C|Fe₁N₄ catalyst is attributable to the presence of Fe₃C NPs that optimizes J_CO of the coexisted Fe–N₄ active sites. In situ attenuated total reflectance-Fourier transform infrared analysis and theoretical calculations reveal that the Fe₃C NPs strengthen the adsorption of CO₂ on the isolated Fe–N₄ sites to accelerate the formation of *COOH intermediate, and hence enhance the whole CO₂ER performance.

This article was published on Advanced Functional Materials: Chen, J. Y.; et al. Adv. Funct. Mater. 2021. DOI: 10.1002/adfm.202110174