Designing Synergistic Lewis Acid‐Base Pairs in Compressed Bismuth‐Copper Oxide for Selective CO ₂ ‐to‐Formate Electrosynthesis

Electrocatalytic carbon dioxide reduction (CO₂RR) to formate represents a sustainable pathway for carbon utilization, yet its industrial deployment remains hindered by insufficient current density and stability of the electrocatalysts. While lattice strain engineering can modulate catalytic performance by altering electronic structures, a major challenge is the lack of a clear mechanistic understanding connecting the induced strain to the activity enhancement. Herein, by precisely engineering lattice strain in an atomically integrated catalytic system, we establish a definitive intrinsic structure-activity relationship, moving beyond conventional correlations with apparent properties. Combined experimental and theoretical investigations demonstrate that compressive strain effectively modulates the electronic structure of the Cu d-orbital and the local electronic states of oxygen vacancies, thereby enhancing the cooperation within the Lewis acid-base pairs. This mechanism facilitates CO₂ adsorption and activation, stabilizes the key ^*HCOO intermediate, and significantly lowers the reaction energy barrier. Consequently, the catalyst exhibits high formate Faradaic efficiency (>95%) over a broad current density range (-100 to -700 mA cm^-2), achieving 96.1% at -576.8 mA cm^-2. This research not only elucidates the synergistic Lewis acid-base catalytic mechanism at the molecular level but also provides universal design principles for the sustainable electro-synthesis of value-added formate.