1f:T51c,Copper catalyzes the electrochemical reduction of CO to valuable C2+ products including ethanol, acetate, propanol, and ethylene. These reactions could be very useful for converting renewable energy into fuels and chemicals, but conventional Cu electrodes are energetically inefficient and have poor selectivity for CO vs H2O reduction. Efforts to design improved catalysts have been impeded by the lack of experimentally validated, quantitative structure–activity relationships. Here we show that CO reduction activity is directly correlated to the density of grain boundaries (GBs) in Cu nanoparticles (NPs). We prepared electrodes of Cu NPs on carbon nanotubes (Cu/CNT) with different average GB densities quantified by transmission electron microscopy. At potentials ranging from −0.3 V to −0.5 V vs the reversible hydrogen electrode, the specific activity for CO reduction to ethanol and acetate was linearly proportional to the fraction of NP surfaces comprised of GB surface terminations. Our results provide a design principle for CO reduction to ethanol and acetate on Cu. GB-rich Cu/CNT electrodes are the first NP catalysts with significant CO reduction activity at moderate overpotential, reaching a mass activity of up to ∼1.5 A per gram of Cu and a Faradaic efficiency >70% at −0.3 V.20:T4d1,Copper is currently the material with the most promise as catalyst to drive carbon dioxide (CO₂) electroreduction to produce value-added multicarbon (C₂₊) compounds. However, a copper catalyst on a carbon-based gas diffusion layer electrode often has poor stability-especially when performing at high current densities-owing to electrolyte flooding caused by the hydrophobicity decrease of the gas diffusion layer during operation. Here, we report a bioinspired copper catalyst on a gas diffusion layer that mimics the unique hierarchical structuring of Setaria's hydrophobic leaves. This hierarchical copper structure endows the CO₂ reduction electrode with sufficient hydrophobicity to build a robust gas-liquid-solid triple-phase boundary, which can not only trap more CO₂ close to the active copper surface but also effectively resist electrolyte flooding even under high-rate operation. We consequently achieved a high C₂₊ production rate of 255 ± 5.7 mA cm^-2 with a 64 ± 1.4% faradaic efficiency, as well as outstanding operational stability at 300 mA cm^-2 over 45 h in a flow reactor, largely outperforming its wettable copper counterparts.

	Year	Citations

References