Cavity‐Networked Copper Nanocatalysts with Acid‐Tolerant Microenvironments for Efficient CO ₂ Electroreduction to Ethylene

Abstract Gasophilic/hydrophobic microstructured Cu nanomaterials address the multi‐carbon (C 2+ ) selectivity bottleneck in electrocatalytic CO 2 reduction reaction (CO 2 RR), yet their morphological control is hindered by low reduction potentials and high surface atomic mobility. This study reports a bioinspired gas‐trapping hydrophobic Cu nanostructure (BGH‐Cu) via in situ electrochemical reconstruction, forming an interconnected cavity network that confers gasophilic/hydrophobic properties. Mechanistic studies reveal cavities act as dynamic electrolyte reservoirs, selectively retaining OH − /K + to suppress proton transport and create a local micro‐alkaline environment, while cavity‐enhanced cation enrichment synergizes with C─C coupling. BGH‐Cu achieves C 2 H 4 Faradaic efficiency of 54.7% at current density of 600 mA cm −2 in strongly acidic conditions (pH 1), with 63.7% single‐pass carbon efficiency and 40 h stability in a membrane electrode assembly configuration. This work provides a non‐extreme synthesis strategy for gasophilic/hydrophobic Cu nanomaterials, elucidates the “cavity microenvironment modulation” mechanism for C 2+ selectivity, and offers a new paradigm for high‐current‐density acidic CO 2 RR to C 2+ products.