Implanting Built-In Electric Field in Heterometallic Phthalocyanine Covalent Organic Frameworks for Light-Assisted CO_(2)Electroreduction

A strategy that enables introducing bimetallic active sites is desired for the exploration of light-sensitive covalent organic framework(COF)-based electrocatalysts in light-assisted CO_(2)electroreduction.Here,salphen-pockets have been implanted into phthalocyanine(Pc)-based COFs through the elaborate design of structural struts;the produced NiPc-DFP-M COFs(M=Ni and Co)possess the advantages of controllable bimetallic centers with different coordination environments,outstanding light sensitivity,and built-in electric-field effects that can be successfully applied in light-assisted CO_(2)electroreduction.Notably,the optimal heterometallic NiPc-DFP-Co COF presents a∼100%Faradic efficiency for CO formation(FECO)in a wide potential range of−0.7 to−1.1 V and∼70%energy efficiency(−0.7 V)under light-irradiation,which is superior to mono-and homometallic COFs and under dark conditions.The high performance can be ascribed to the synergistic effect of the NiPc and Co-salphen pockets that can largely reduce the rate-determining energy-barrier and enhance the electron density to boost the light-assisted activity as supported by density functional theory calculations.A series of bimetallic Pc-based NiPc-DFP-M COF(M=Ni and Co)with integrated salphen-pockets and NiPc units have been synthesized and successfully applied in efficient light-assisted CO_(2)electroreduction.