Efficient electrocatalytic carbon dioxide reduction with tetraphenylethylene- and porphyrin-based covalent organic frameworks

Abstract

Electrochemical conversion of carbon dioxide into high value-added fuels or chemicals is a promising and sustainable way to alleviate the negative effects of excessive CO₂ emissions. Covalent organic frameworks (COFs) are a kind of promising electrocatalyst due to their ordered porous structure and large number of accessible active sites. However, the low current density of COFs limits their further applications. Therefore, we developed a couple of new COFs (TPE-CoPor-COF and TPTPE-CoPor-COF) based on tetraphenylethene and cobalt porphyrin derivatives with enhanced intramolecular electron transfer, in which the tetraphenylethene moiety acted as an electron donor (D) and the cobalt porphyrin moiety as an electron acceptor (A). Fortunately, TPE-CoPor-COF and TPTPE-CoPor-COF exhibit excellent CO faradaic efficiencies (FE_CO) (i.e., 91–95% from −0.6 to −1.0 V vs. RHE for TPE-CoPor-COF; 89–96% from −0.7 to −1.0 V vs. RHE for TPTPE-CoPor-COF). In particular, the maximum CO partial current density (j_CO) of TPE-CoPor-COF reaches up to −30.4 mA cm⁻² at −1.0 V vs. RHE in a H-cell, exceeding most of reported COF electrocatalysts. Our work should be conducive to the development of new COF-based electrocatalysts for efficient CO₂ reduction.