Fe-N4O-C Nanoplates Covalently Bonding on Graphene for Efficient CO2 Electroreduction and Zn-CO2 Batteries

Abstract

Electrochemical carbon dioxide (CO2) reduction into value-added products holds great promise in moving toward carbon neutrality but remains a grand challenge due to lack of efficient electrocatalysts. Herein, the nucleophilic substitution reaction is elaborately harnessed to synthesize carbon nanoplates with a Fe-N4O configuration anchored onto graphene substrate (Fe-N4O-C/Gr) through covalent linkages. Density functional theory calculations demonstrate the unique configuration of Fe-N4O with one oxygen (O) atom in the axial direction not only suppresses the competing hydrogen evolution reaction, but also facilitates the desorption of *CO intermediate compared with the commonly planar single-atomic Fe sites. The Fe-N4O-C/Gr shows excellent performance in the electroreduction of CO2 into carbon monoxide (CO) with an impressive Faradaic efficiency of 98.3% at −0.7 V versus reversible hydrogen electrode (RHE) and a high turnover frequency of 3511 h−1. Furthermore, as a cathode catalyst in an aqueous zinc (Zn)-CO2 battery, the Fe-N4O-C/Gr achieves a high CO Faradaic efficiency (≈91%) at a discharge current density of 3 mA cm−2 and long-term stability over 74 h. This work opens up a new route to simultaneously modulate the geometric and electronic structure of single-atomic catalysts toward efficient CO2 conversion.