(a, b) Structural characterization of the cavity Cu₂O precursor: SEM and TEM images. (c) C₂₊ partial current densities. (d) Stability test of cavity Cu throughout 12 h of CO₂ electrolysis at 200 mA cm^–2. Calculated concentration and distribution of species: CO₂ (e), C₁ (f), C₂ (g), and C₃ (h) concentrations on the cavity structure. The units of the CO₂, C₁, C₂, and C₃ concentrations were all mM in the color scale, and the scale bars are 100 nm. Adapted from Ref. [29]. Copyright 2023, American Chemical Society. (i) SEM-energy dispersive X-ray spectroscopy (EDS) mapping showing hollow structure and homogenous distribution of Cu and Zn. (j) Change of FE of C₂₊ product at different Cu/Zn atomic composition. (k) Schematic illustration of Cu₆Zn-h catalyst giving C₂₊ product. Simulated concentration and flux distribution of (l) CO in Cu₆Zn-h and Cu₆Zn-b, (m) simulated concentration of OH⁻ in Cu₆Zn-h and Cu₆Zn-b (color scale, concentration in mM). Adapted from Ref. [30]. Copyright 2025, Wiley-VCH GmbH.