Heterostructure construction of covalent organic frameworks/Ti₃C₂-MXene for high-efficiency electrocatalytic CO₂ reduction

Covalent organic frameworks (COFs), as typical organic functional materials, have shown promising potential for application in photo/electrocatalysis, especially in the electrocatalytic CO2 reduction reaction (CO2RR). COFs can ensure effective CO2 adsorption and rapid mass transfer by virtue of controllable active sites and a large specific surface area. However, the inefficient interlayer conductivity of most COFs leads to a low electron transfer rate that restricts their practical applications. In this work, porphyrin-based covalent organic framework nanosheets (Por-COF) were vertically grown on the modified MXene surface for efficient electrocatalytic CO2RR. The large exposed MXene surface serves as a carrier "bridge" for dispersed COFs, which can endow heterojunctions with more active sites and fast ion transport channels. The optimal sample can exhibit superior efficient CO2RR performance, in which the faradaic efficiency of the CO2-to-CO conversion was 97.28% at -0.6 V vs. RHE, and the bias current density was -9.33 mA cm(-2) at -1.0 V vs. RHE.