Lewis Acid Adsorption Promotes CO ₂ Enrichment for Efficient Formic Acid Electrosynthesis on Reconstructed Bi ₂ O ₂ CO ₃ in Acidic Media

Abstract In acidic media, electrocatalytic CO 2 reduction to formic acid (HCOOH) represents a promising strategy for producing value‐added chemicals. However, a critical challenge persists in enhancing CO 2 adsorption and activation to suppress hydrogen evolution and boost product selectivity. Here, a Lewis acidic Zr‐oxo cluster‐rich porous confined structure decorated Bi 2 O 2 CO 3 catalyst (Bi 2 O 2 CO 3 @PCN) is constructed via in situ electroreconstruction, which effectively promotes surface CO 2 enrichment and K + confinement in acidic conditions. Spatially adjacent Zr‐oxo clusters enhance CO 2 adsorption at the interface through Lewis acid‐base interactions, facilitating the *OCHO intermediate formation. The optimized Bi 2 O 2 CO 3 @PCN catalyst achieves a high HCOOH Faradaic efficiency (FE) of 95% across a broad potential window and demonstrates a 5.9‐fold higher mass activity compared to Bi 2 O 2 CO 3 in acidic media at ‒1.8 V versus reversible hydrogen electrode. Notably, Bi 2 O 2 CO 3 @PCN exhibits superior HCOOH FE compared to Bi 2 O 2 CO 3 under low‐concentration CO 2 flow. Mechanistically, the strong binding of CO 2 molecules at Bi–O–Zr interfacial sites significantly lowers the hydrogenation barrier, while K + enrichment repels protons and suppresses the hydrogen evolution reaction. This work underscores the pivotal role of surface confinement and Lewis acidic sites in regulating interfacial microenvironments and CO 2 adsorption, highlighting their potential for efficient conversion of low‐concentration CO 2 .