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

The sustainable production of methane (CH4) via the electrochemical conversion of carbon dioxide (CO2) 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 (C2+) products at neighboring catalytic sites. Herein, a conjugated copper phthalocyanine polymer (CuPPc) is designed by a facile solid-state method for highly selective CO2-to-CH4 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 CH4. As a result, the CuPPc catalyst exhibits a high CH4 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 CO2 reduction.