Organic Molecule-Modified Copper Catalyst Enables Efficient Electrochemical Reduction of CO2-to-methane

Renewable electricity powered CO2 electroreduction to methane is promising for producing highly specific combustion fuels. However, the reduction process is severely limited by poor selectivity and chemical activity at high electrolysis reaction rates. Herein, we produce tandem electrocatalysts by combining organic small molecules (perylene-3,4,9,10-tetracarboxylic dianhydride and pentacene) with copper catalysts supported on microporous polytetra fluoroethylene with enhanced *CO protonation and weakened hydrogen evolution. Experimental results show that the tandem catalysts effectively suppress the two-electron reduction process associated with hydrogen (H2) and carbon monoxide (CO) production while inhibiting the multielectron con-version process associated with ethylene production (C2H4). As a result, the tandem catalysts enable an effi-cient eight-electron transfer for electrochemical reduction of CO2 and demonstrate a -50 % (+/- 2%) Faradaic efficiency for CO2-to-methane conversion at a partial current density of 220 mA cm-2 in 1 M KHCO3 solution. Notably, the selectively of CO2-to-CH4 is 2.7 times higher than that of a copper catalyst sup-ported on microporous polytetra fluoroethylene which is known to produce C2H4 with -50 % Faradaic effi-ciency. This work paves the way for tuning *CO dimerization and hydrogen evolution reaction to maximize CO2 methanation by using abundant organic molecular materials.