Electron-Pump Driven Redox Design for Boosting the Reactivity of Ceria

Electron-pump behavior can enhance charge transfer and redox cycling in heterogeneous catalysis, but its dynamic evolution under reaction conditions is difficult to control. Herein, we incorporate Nb⁵⁺ into the CeO₂ lattice via a two-step synthesis to act as a donor dopant that functions as an electron-pumping agent, tuning electron transfer and stabilizing the Ce³⁺/Ce⁴⁺ redox cycle. Nb⁵⁺ doping promotes Ce³⁺ formation and accelerates reversible Ce³⁺/Ce⁴⁺ cycling, which leads to improved activity, selectivity, and stability of CeO₂ for the ammonia selective catalytic reduction reaction. In situ spectroscopy measurements reveal that accelerated electron cycling stimulates the activation of a variety of molecules, including complexes of O₂, NO, and NH₃. The optimized Ce_0.8Nb_0.2O₂ catalyst achieves >98% NO conversion and >98% N₂ selectivity from 200 to 400 °C and exhibits excellent H₂O and SO₂ resistance. This work establishes a clear structure-activity relationship centered on electron-pump function reinforcement and offers mechanistic insight into controlling the dynamic electron-transfer evolution during the catalytic reaction.