Highly exposed atomic Fe–N active sites within carbon nanorods towards electrocatalytic reduction of CO2 to CO

Abstract

Single-atom transition-metal-anchored nitrogen-doped carbon (M-N-C) materials show great potential in electrochemical reduction of CO2 to CO. However, the development of catalysts with high exposure density of M-Nx active sites remains key challenge. Herein, we report an atomically dispersed and highly exposed Fe coordinated to nitrogen (Fe-Nx) active sites doped within carbon nanorods (Fe–N–C) by pyrolysis of sea urchin-like FeOOH-polyaniline (FeOOH-PANI) composite. Results from X-ray photoelectron spectra (XPS) and operando X-ray absorption fine structure (XAFS) spectra confirmed the atomically dispersed Fe species and indicated the Fe coordinated with four N atoms to form the highly exposed Fe-Nx active sites. Detailed examination of the Fe–N–C electrocatalyst reveals a high selectivity for CO2 reduction, presenting CO Faradaic efficiency (FECO) of 95% with CO partial current density (jCO) of 1.9 mA cm−2 at a relatively low overpotential of 530 mV. The high-performance is a result of the porous structure of catalyst with highly exposed Fe-Nx active sites, as well as the larger specific surface area and electrochemical active surface area. Our work proposes an effective and feasible way to designing M-N-C catalysts for efficient electrochemical reduction of CO2.