Regulating the Oxygen Vacancy on Bi2MoO6/Co3O4 Core-Shell Nanocage Enables Highly Selective CO2 Photoreduction to CH4

Abstract

Photocatalytic CO2 reduction reaction (CO2RR) into high-value-added fuels has received significant attention, yet multiple electron and proton processes involved in CO2RR result in low selectivity. Herein, a strategy involving oxygen vacancies (Ovs)-enriched Bi2MoO6 coated on ZIF-67-derived Co3O4 to construct well-defined core-shell nanocage is developed, which drives effective CO2 photoconversion to CH4 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 CO2 reduction occurring on Bi2MoO6 and H2O oxidation set in Co3O4. Numerous exposed Bi2MoO6 with Ovs formed in Bi─O bond by ethylene glycol mediated approach promotes the CO2 adsorption and charge separation efficiency, which can optimize the reaction kinetics and thermodynamics, facilitating the hydrogenation of key intermediate *CO to generate CH4. This work provides a new strategy for controlled oxygen vacancy generation on photocatalysts to achieve high-performance CO2 methanation.