Nanoconfinement Engineering over Hollow Multi‐Shell Structured Copper towards Efficient Electrocatalytical C−C coupling

Nanoconfinement provides a promising solution to promote electrocatalytic C-C coupling, by dramatically altering the diffusion kinetics to ensure a high local concentration of C₁ intermediates for carbon dimerization. Herein, under the guidance of finite-element method simulations results, a series of Cu₂ O hollow multi-shell structures (HoMSs) with tunable shell numbers were synthesized via Ostwald ripening. When applied in CO₂ electroreduction (CO₂ RR), the in situ formed Cu HoMSs showed a positive correlation between shell numbers and selectivity for C₂₊ products, reaching a maximum C₂₊ Faradaic efficiency of 77.0±0.3 % at a conversion rate of 513.7±0.7 mA cm⁻² in a neutral electrolyte. Mechanistic studies clarified the confinement effect of HoMSs that superposition of Cu shells leads to a higher coverage of localized CO adsorbate inside the cavity for enhanced dimerization. This work provides valuable insights for the delicate design of efficient C-C coupling catalysts.