Polarized Active Pairs at Grain Boundary Boost CO₂ Chemical Fixation

The chemical fixation of CO₂ as a C1 feedstock is considered one of the most promising ways to obtain long-chain chemicals, but its efficiency was limited by the ineffective activation of CO₂. Herein, we propose a grain boundary engineering strategy to construct polarized active pairs with electron poor-rich character for effective CO₂ activation. By taking CeO₂ as a model system, we illustrate that the polarized "Ce⁴⁺-Ce³⁺-Ce⁴⁺" pairs at the grain boundary can simultaneously accept and donate electrons to coordinate with O and C, respectively, in CO₂. By the combination of synchrotron radiation in situ technique and density functional theory calculations, the mechanism of the catalytic reaction has been systematically investigated. As a result, the CeO₂ nanosheets with a rich grain boundary show a high DMC yield of 60.3 mmol/g_cat with 100% atomic economy. This study provides a practical way for the chemical fixation of CO₂ to high-value-added chemicals via grain boundary engineering.