Synergistic Electric Field and Confinement Effects in Porous Cu ₂ O Octahedra Enable CO ₂ Electroreduction across pH Conditions

Conventional catalyst design for CO₂ electroreduction is fundamentally constrained by the pH of the bulk electrolyte as it affects catalyst durability, reaction pathways, and overall performance. Herein, we break this paradigm by using three-dimensional ordered porous Cu₂O octahedra (3DOP Cu₂O-OC) to decouple the local reaction microenvironment from the bulk electrolyte. This architecture synergistically integrates a built-in electric field and nanoconfinement effects, which work in concert to enrich electrolyte cations and enhance local CO₂ concentration, thereby creating a stable microenvironment independent of the electrolyte pH. Moreover, the C-C coupling reaction via forming a *OCCOH intermediate is kinetically promoted at the defective Cu⁺/Cu⁰ interface sites confined in the nanopores. Leveraging these synergistic effects, 3DOP Cu₂O-OC achieves high Faradaic efficiencies of 84.0 ± 1.0% in alkaline and 74.0 ± 0.2% in acidic electrolytes for multicarbon products at current densities up to -1.0 and -0.8 A cm⁻², respectively. This work establishes a general design model for creating adaptive microenvironments by leveraging synergistic physical effects within nanoarchitectures, providing an important design principle for universal electrocatalyst design.