A stable and conductive phthalocyanine-porphyrin two-dimensional carbon-rich conjugation frameworks for highly selective electroreduction of carbon dioxide to dimethyl carbonate

Abstract

Electrocatalytic reduction of carbon dioxide (CO2RR) to long-chain chemicals, such as dimethyl carbonate (DMC), is considered an effective strategy for addressing excessive CO2 emissions. However, the underlying reaction mechanism remains unclear. In this work, based on phthalocyanine-porphyrin 2D CCFs, a tandem catalyst composed of Fe and other transition metals (TMs) co-embedded in rectangular extended Pc and TM-embedded in porphyrins is proposed. Among various catalysts, the Fe-Sc-Pc-Co-TPP-CCF catalyst stands out due to its unique catalytic sites that can efficiently convert both C1 and C2 intermediates simultaneously. This catalyst exhibits superior CO2 adsorption capacity and excellent catalytic activity, which can be attributed to the ability of the d orbitals of both Fe and TMs to accept lone pairs and feedback electrons from CO2. Additionally, the synergistic effect between the two different metals enhances the adsorption and activation of CO2 molecules. The detailed process of CO2 reduction to DMC on the Fe-Sc-Pc-Co-TPP-CCF catalyst was systematically investigated, and it was identified that the direct coupling of CO2 and methanol to form DMC is the optimal pathway. To evaluate the catalytic performance of the catalyst, we conducted density functional theory calculations. The results show that the Fe-Sc-Pc-Co-TPP-CCF catalyst exhibits an inhibitory effect on competing reactions of CO2RR, such as proton-coupling reaction and HER. Combined with DFT calculations, the reaction mechanism at the phthalocyanine-porphyrin 2D CCFs was systematically studied, providing novel insights into the potential pathway for the chemical conversion of CO2 into long-chain chemicals.