Functionalizing Cu nanoparticles with fluoric polymer to enhance C2+product selectivity in membraned CO2 reduction

Copper-based nanomaterials are attractive in CO2 electroreduction into valuable chemicals but still suffer from limited selectivity of C2+ products due to the parasitic hydrogen evolution reaction and inefficient dimerization of absorbed CO intermediate (*CO). Herein, we report an in situ polymerization strategy to coat hydrophobic polymer containing methoxyl silane ((CH3O)3Si-) and trifluoromethyl (-CF3) functional groups on Cu nanoparticles. The optimized Cu-poly exhibits a high Faradaic efficiency of 71.08 % and a remarkable partial current density of 355.4 mA cm-2 for C2+ products in a membrane electrode assembly electrolyzer using a bicarbonate electrolyte. A combined study of density functional theory calculations and in situ infrared characterizations indicates that the enhanced performances could be ascribed to the decreased formation energy of *COCOH, induced by the withdraw-electron effect of -CF3 and enhanced coverage of *CO. This work offers a new insight in tuning the electrocatalytic microenvironment through the surface polymerization process.