Oxygen vacancy-mediated lewis acid-base pairs on Ce-doped BiOI enable efficient CO₂ conversion

Abstract

CO₂ cycloaddition with epoxides for producing cyclic carbonates is a promising route that aligns with environmental sustainability and economic feasibility. Metal oxyhalides, which contain inherent lattice halogen ions that can act as built-in nucleophiles, offer a distinctive strategy of designing efficient, heterogeneous catalysts for CO₂ cycloaddition. Herein, a series of highly dispersed Ce-doped BiOI (Ce_xBi_1-xOI) catalysts were developed via a one-pot solvothermal method. The introduction of oxyphilic Ce ions enhances the adsorption and activation of epoxides, thus improving the catalytic performance in CO₂ cycloaddition. Experimental characterizations reveal that Ce doping facilitates the formation of oxygen vacancy-mediated Lewis acid-base pairs (Bi–O_v–Ce³⁺···I⁻). In this configuration, the O_v–Ce³⁺···I⁻ strengthens the epoxides adsorption and subsequent epoxy ring-opening, while the Bi–O_v supplies CO₂ adsorbed site. This synergistic interaction reduces the apparent activation energy (70.67 kJ∙mol^–1 for Ce_0.1Bi_0.9OI vs. 108.09 kJ∙mol^–1 for BiOI) of the CO₂ cycloaddition with butylene oxide. Under solvent- and cocatalyst-free conditions, the optimized Ce_0.1Bi_0.9OI catalyst achieved a butylene carbonate yield of 91%. This work provides a feasible strategy for designing efficient catalysts of CO₂ conversion by constructing reinforced synergistic Lewis acid-base sites.

Keywords

CO₂ cycloaddition / cyclic carbonates / heterogeneous catalysis / Ce doping / oxygen vacancy

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Higher Education Press 2026

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