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

Abstract

On the path to deploying the electrochemical CO₂ reduction reaction (CO₂RR) to CO, the narrow potential range under the high Faraday efficiency of CO (FE_CO) 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 FE_CO 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.