A Versatile Transition Metal Ion-Binding Motif Derived From Covalent Organic Framework For Efficient Co2 Electroreduction

We demonstrate a versatile transition metal ion-binding motif for constructing highly efficient metal atom-embedded carbon catalysts for electrochemical CO production. It is a mesoporous N-doped carbon (N-C) derived from a covalent organic framework via molten-salt assisted carbonization. Three different transition metals (Co, Fe or Ni) have been immobilized into the N-rich mesopores via ion coordination, forming catalysts with isolated and coordinately unsaturated metal-N moieties. These catalysts all exhibit excellent electrocatalytic activities for CO2-to-CO conversion with a high faradaic efficiency > 80 % and a high current density > 10 mA cm(-2) at modest overpotentials around 500 mV. Using Ni- or Fe-N-C, a highly selective (> 95 %) CO generation was observed. By performing the structure-property analysis with three other N-C materials as control, such high performance is ascribed to the efficient metal-N catalytic sites generated by the cooperative immobilization of metal atoms with pyridinic-N and pyrrolic-N species in the mesoporous carbon matrix.