Asymmetric Co-O_v-In sites-boosted interfacial electron transfer and CO₂ adsorption for efficient CO₂ photoreduction

Photocatalysis for converting CO₂ into value-added chemicals provides a sustainable path toward advancing carbon neutrality. However, how to precisely tailor the specific reactive sites to effectively promote CO₂ adsorption and activation remains a significant challenge. To address this challenge, a heteroatom substitution strategy was employed to fabricate Co-doped defect-rich In₂O₃ (Co-In₂O₃/O_v) photocatalyst. Co-replaced the partial substitution of In³⁺ induced an asymmetric distribution of electrons around In atoms, generated neighboring oxygen vacancies (O_v), and established asymmetric Co-O_v-In sites, enabling highly efficient photocatalytic CO₂ reduction. Systematic experiments and theoretical calculations reveal that the asymmetric Co-O_v-In sites effectively facilitate CO₂ adsorption/activation through a stable In-C-O-Co intermediate. In-situ infrared spectroscopy together with Gibbs free energy analysis further elucidated that CO₂ bending with smaller O-C-O angle and CO bond weakening lower the barrier for the formation of the key *COOH intermediate, thereby steering the reaction toward selective CO evolution. Under visible-light irradiation, the optimized Co-In₂O₃/O_v exhibits a high CO production rate of 3.45 mmol g^-1 h^-1 with 86% selectivity, representing a 7.3-fold enhancement over undoped In₂O₃. This work highlights a novel mechanistic paradigm for applying asymmetric active sites in CO₂ photoreduction and offers both experimental and theoretical guidance to design highly efficient photocatalysts for solar-driven CO₂ conversion.