Tunable Oxygen Vacancy Clusters Enhanced Catalytic Activity of CeO₂ Nanorods on CO₂ Cycloaddition

Constructing heterogeneous halogen-free catalysts featuring efficiently activated CO₂ and epoxides for the synthesis of cyclic carbonates via an atom-economical route is significant but remains a big challenge. In this work, we develop an atmosphere-assisted strategy for preparing mesoporous CeO₂ nanorods with tunable oxygen vacancy cluster concentrations, which boosts the performance of CO₂ cycloaddition. Pair distribution function (PDF) analysis elucidates that oxygen vacancy clusters regulate the dynamic equilibrium of the multiscale structure of CeO₂ via a synergistic "compression-expansion" mechanism. Furthermore, the high concentrations of oxygen vacancy clusters form abundant frustrated Lewis pairs (FLP) sites, which remarkably promote the adsorption and activation of CO₂ with epoxides. Thus, the performance of CO₂ cycloaddition was substantially intensified. A 95% yield of cyclic carbonate was obtained when the reaction was conducted with RNR-CeO₂-H₂ at 110 °C. Moreover, the kinetic properties and the catalytic mechanism of CO₂ cycloaddition on FLP sites in RNR-CeO₂-H₂ were investigated based on the in situ DRIFTS and DFT calculations. Thus, this work provides new insights into the design of high-performance catalysts with tunable FLP sites for the efficient activation and conversion of CO₂ into value-added chemicals by modulating oxygen vacancy cluster concentrations.