Molecular Modulation of Sequestered Copper Sites for Efficient Electroreduction of Carbon Dioxide to Methane

Abstract The sustainable production of methane (CH 4 ) via the electrochemical conversion of carbon dioxide (CO 2 ) is an appealing approach to simultaneously mitigating carbon emissions and achieving energy storage in chemical bonds. Copper (Cu) is a unique material to produce hydrocarbons and oxygenates. However, selective methane generation on Cu remains a great challenge due to the preferential *CO dimerization pathway toward multi‐carbon (C 2+ ) products at neighboring catalytic sites. Herein, a conjugated copper phthalocyanine polymer (CuPPc) is designed by a facile solid‐state method for highly selective CO 2 ‐to‐CH 4 conversion. The spatially isolated CuN 4 sites in CuPPc favor the *CO protonation to generate the key *CHO intermediate, thus significantly promoting the formation of CH 4 . As a result, the CuPPc catalyst exhibits a high CH 4 Faradaic efficiency of 55% and a partial current density of 18 mA cm −2 at −1.25 V versus the reversible hydrogen electrode. It also stably operates for 12 h. This study may offer a new solution to regulating the chemical environment of the active sites for the development of highly efficient copper‐based catalysts for electrochemical CO 2 reduction.