Electrochemical CO₂ Reduction with Atomic Iron-Dispersed on Nitrogen-Doped Graphene

Electrochemical reduction of CO₂ provides an opportunity to reach a carbon-neutral energy recycling regime, in which CO₂ emissions from fuel use are collected and converted back to fuels. The reduction of CO₂ to CO is the first step toward the synthesis of more complex carbon-based fuels and chemicals. Therefore, understanding this step is crucial for the development of high-performance electrocatalyst for CO₂ conversion to higher order products such as hydrocarbons. Here, atomic iron dispersed on nitrogen-doped graphene (Fe/NG) is synthesized as an efficient electrocatalyst for CO₂ reduction to CO. Fe/NG has a low reduction overpotential with high Faradic efficiency up to 80%. The existence of nitrogen-confined atomic Fe moieties on the nitrogen-doped graphene layer is confirmed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure analysis. The Fe/NG catalysts provide an ideal platform for comparative studies of the effect of the catalytic center on the electrocatalytic performance. The CO₂ reduction reaction mechanism on atomic Fe surrounded by four N atoms (Fe–N₄) embedded in nitrogen-doped graphene is further investigated through density functional theory calculations, revealing a possible promotional effect of nitrogen doping on graphene.