Organic molecule-modified copper catalyst enables efficient electrochemical reduction of CO2-to-methane

Renewable electricity powered CO 2 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 (H 2 ) and carbon monoxide (CO) production while inhibiting the multielectron conversion process associated with ethylene production (C 2 H 4 ). As a result, the tandem catalysts enable an efficient eight-electron transfer for electrochemical reduction of CO 2 and demonstrate a ∼ 50 % (±2%) Faradaic efficiency for CO 2 -to-methane conversion at a partial current density of 220 mA cm −2 in 1 M KHCO 3 solution. Notably, the selectively of CO 2 -to-CH 4 is 2.7 times higher than that of a copper catalyst supported on microporous polytetra fluoroethylene which is known to produce C 2 H 4 with ∼ 50 % Faradaic efficiency. This work paves the way for tuning *CO dimerization and hydrogen evolution reaction to maximize CO 2 methanation by using abundant organic molecular materials.