Hierarchically porous N-doped carbon confined single-atom Fe catalyst for efficient electrochemical CO <sub>2</sub> reduction
Guanghuan Ma, Yang Chen, Hui Li, Ying Sun, Hua Fan, Shuoshuo Jiang, Xin Cui, Tianyi Ma
Abstract
Electrochemical CO<sub>2</sub> reduction reaction (CO<sub>2</sub>RR) is a promising process for reducing CO<sub>2</sub> emissions and producing high-value chemicals. However, this process remains hindered by diffusion-limited mass transfer, low activity, and high overpotentials. Here, we controllably prepared hierarchically porous nitrogen-doped carbon, carbon nanosheets, and carbon nanotubes confined single-atom Fe catalysts for electrochemical CO<sub>2</sub> reduction. The hierarchically porous Fe-N-C (Fe-HP) exhibited prominent performance with a Faradaic efficiency of CO (FE<sub>CO</sub>) up to 80% and a CO partial current density (<i>j</i><sub>CO</sub>) of −5.2 mA·cm<sup>−2</sup> at −0.5 V vs. reversible hydrogen electrode (RHE), far outperforming the single-atom Fe on N-C nanosheets (Fe-NS) and N-C nanotubes (Fe-NT). The detailed characterizations and kinetic analysis revealed that the hierarchically porous structure accelerated the mass transfer and electron transfer processes toward single-atom Fe sites, promoting the desorption of CO and thereby enhancing CO<sub>2</sub> reduction efficiency. This study provides a promising approach to designing efficient single-atom catalysts with porous structures for energy conversion applications.