Mechanochemical Method-Induced Construction of the Mn–Ov–Ce Bridged Structure to Promote Oxygen Dynamic Migration and Buffer Air–Fuel Ratio Fluctuations

Abstract

Urban driving conditions characterized by frequent start-and-stop operations challenge the dynamic responsiveness of three-way catalysts (TWCs), and the rapid response to oxygen is crucial to buffering air–fuel ratio fluctuations. Herein, we synthesized nonstoichiometric Mn_1.5Fe_1.5O₄ (MF) spinel with excellent oxygen storage capacity and introduced it into Rh/CeO₂-ZrO₂-Al₂O₃ (Rh/CZA) via high-energy ball milling to form the composite structure TWCs. The catalysts significantly show a wide operating window and similar steady-state catalytic effects under lean–rich burn oscillating conditions (λ = 0.98–1.02; switching frequency, 1 Hz). MF incorporation not only retains its excellent oxygen storage capacity but also results in the generation of abundant oxygen vacancies on MF-CZ heterogeneous interfaces, thus synergistically promoting the rapid formation and migration of active oxygen species. Furthermore, the lower oxygen vacancy formation energy (E_form) for the Mn–O_v–Ce bridged structure promotes the rapid formation of interfacial oxygen vacancies and the facile desorption of active oxygen species, which is important to enhance the reaction rates and buffer air–fuel ratio fluctuations. This study presents a strategy to enhance the dynamic responsiveness of TWCs and offers critical insights into the formation mechanisms and migration of the active oxygen species process on heterogeneous interfaces.