Industrial-Grade CO ₂ -to-Formate Electrocatalysis via A-Site Deficiency-Doping Synergy in Orbital-Dominated Indium Perovskites

Indium (In)-based catalysts hold great promise for the electrochemical CO2 reduction reaction (CO2RR) toward HCOOH formation, yet the lack of precise p-band control and structural instability under industrial current densities severely limit their selectivity and durability. Here, we break ground by designing a series of La1–xSryInO3 perovskites that exhibit electronic tunability and lattice robustness, achieved through smart A-site modulation. Integrated cross-scale analyses revealed that La0.8Sr0.1InO3, engineered via an optimally balanced coregulation of A-site La-deficiency and Sr-doping, most effectively promoted oxygen vacancy formation and electron enrichment at the In-site. This dual effect upshifted the In 5p-band center toward the Fermi Level and enhanced In–O bond covalency through stronger hybridization between In 5p and O 2p orbitals. The elevated p-band center weakened *CO2 adsorption while stabilizing *OCHO intermediates, thereby accelerating rate-determining *CO2 protonation, while the reinforced In–O covalency strengthened the bonding framework, bolstering structural integrity of the In–O lattice. As a result, La0.8Sr0.1InO3 achieved a maximum HCOOH Faradaic efficiency (FEHCOOH) of 92.49% at 300 mA cm–2, and even at 500 mA cm–2, it still retained an FEHCOOH of 91.93%, whereas LaInO3 and In2O3 dropped dramatically to 74.32% and 59.35%, respectively. Moreover, during a 48 h stability test, La0.8Sr0.1InO3 maintained a steady potential of −2.01 ± 0.17 V while preserving its perovskite structure, with FEHCOOH stabilizing at 91.17 ± 1.90%. This study provides a universal design paradigm via smart A-site modulation for advanced perovskite-based catalysts.