Tailoring dual-hydrophobic microenvironment for tandem CO/CO feedstock to enhance CO electroreduction on Cu-based catalysts.

Achieving high selectivity for value-added products in the electrochemical reduction of CO remains challenging due to severe hydrogen evolution, sluggish CO mass transport and low *CO coverage. Herein, we integrate aerophilic SiO and polymer-functionalized copper nanoparticles (Cu-poly) to construct a hierarchical-hydrophobic Cu-poly/SiO composite, which limits the accessibility of HO, improves the local concentration of CO and enhances the dimerization of *CO-*CO. Comprehensive investigation using X-ray absorption spectroscopy, infrared spectroscopy and molecular dynamics simulations indicates that the polymer and SiO elevate the oxidation state of Cu species, enhance the CO diffusion coefficients (from 5.27 × 10 on Cu to 8.81 × 10 cm s on Cu-poly/SiO) and enrich the local *CO concentration. The Cu-poly/SiO electrode delivers an enhanced faradaic efficiency of 60.54% for C products, compared to 46.1% of Cu at 600 mA cm. Notably, a high FE of 36.91% and partial current density of 221.46 mA cm are achieved for CH generation in membrane electrode assembly devices adopting an aqueous bicarbonate electrolyte. This work provides a valuable insight into designing catalytic microenvironments of electrocatalysts for enhancing carbonaceous products by facilitating the co-electrolysis of CO and -generated *CO.