Regulating the Oxygen Vacancy on Bi 2 MoO 6 /Co 3 O 4 Core‐Shell Nanocage Enables Highly Selective CO 2 Photoreduction to CH 4

Abstract Photocatalytic CO 2 reduction reaction (CO 2 RR) into high‐value‐added fuels has received significant attention, yet multiple electron and proton processes involved in CO 2 RR result in low selectivity. Herein, a strategy involving oxygen vacancies (Ovs)‐enriched Bi 2 MoO 6 coated on ZIF‐67‐derived Co 3 O 4 to construct well‐defined core‐shell nanocage is developed, which drives effective CO 2 photoconversion to CH 4 with nearly 100% selectivity and high apparent quantum efficiency of 2.5% at 420 nm in pure water under simulated irradiation. Theoretical calculations and experiments exhibit that the potential difference stemming from the built‐in electric field provides guarantee for CO 2 reduction occurring on Bi 2 MoO 6 and H 2 O oxidation set in Co 3 O 4 . Numerous exposed Bi 2 MoO 6 with Ovs formed in Bi─O bond by ethylene glycol mediated approach promotes the CO 2 adsorption and charge separation efficiency, which can optimize the reaction kinetics and thermodynamics, facilitating the hydrogenation of key intermediate *CO to generate CH 4 . This work provides a new strategy for controlled oxygen vacancy generation on photocatalysts to achieve high‐performance CO 2 methanation.