The axial ligands optimized activity of CO2 electroreduction to CO over penta-coordinated single atom iron–nitrogen–carbon catalysts

Abstract

Metal-nitrogen-carbon materials, especially Fe–N–C, are currently at the forefront of interests in electrocatalysis owing to their low price and excellent performance in electrochemical CO2 reduction reaction (CO2RR). It was reported recently that Fe4N and Fe2N modified FeN4 structures, namely penta-coordinated FeN4–L with an axial ligand, would show better performance than the pristine FeN4 structure for CO2 reduction reaction. In this work, microkinetic models were developed and the production rate of CO was calculated over FeN4-based structures. The results suggested that the weaker adsorption of CO over FeN4-L structures, which is originated from the weakened donation and backdonation between CO and the central Fe upon ligand coordination, significantly enhances the CO production rate. Inspired by these results, we further constructed 27 penta-coordinated single iron models with axial ligands and addressed the CO production rate explicitly, and several candidates that would show high activity towards the CO production are identified from the activity map.