Fe1N4–O1 site with axial Fe–O coordination for highly selective CO2 reduction over a wide potential range

On the path to deploying the electrochemical CO2 reduction reaction (CO2RR) to CO, the narrow potential range under the high Faraday efficiency of CO (FECO) still blocks its ultimate practical viability. Engineering the electronic structure via heteroatom doping is supposed to be efficient. However, a feasible synthesis and precise control are still challenging. Here, we propose a fast-pyrolyzing and controllable-activation strategy to construct an O-rich carbonaceous support and atomically dispersed FeN4 site with axial O coordination (Fe1N4–O1), which was confirmed by aberration-corrected electron microscopy and X-ray absorption spectroscopy. A wide potential range of 310 mV (−0.56 V to −0.87 V vs. RHE) could be achieved when FECO was continuously maintained at nearly 100%, which exceeded the existing results to the best of our knowledge. DFT calculations revealed that the superior performance originated from the axial O-coordination induced electronic localization enhancement, which could facilitate the desorption of CO and increase the energy barrier for the competitive hydrogen evolution reaction.