Dynamic Mn–VO Associates Boosted Molecular Oxygen Activation for Benzene Combustion on Mn-Doped Mesocrystalline CeO2

Abstract

Highly efficient molecular oxygen activation over transition metal oxides toward catalytic abatement of aromatic volatile organic compounds (AVOCs) is possible yet challenging due to the easily deactivated surface oxygen vacancy (V_O). Herein, dynamic Mn–V_O associates were crafted onto the Mn-incorporated CeO₂ mesocrystal (Mn/meso-CeO₂) surface with Mn substituting a Ce atom through an easy-to-handle precipitation strategy. Experiments and theoretical calculation demonstrated that the asymmetric surface Mn–O–Ce configuration induced electron delivery from the low-valent Mn to adjacent Ce, destabilizing the circumambient O atoms and facilitating the formation of dynamic Mn–V_O associates. Compared to pristine meso-CeO₂, the Mn/meso-CeO₂ with dynamic Mn–V_O associates could efficiently activate O₂ into a superoxide radical and a peroxanion (O₂^•– and O₂^2–) at higher reaction temperature (over 200 °C). Meanwhile, the O atom adjacent to Mn featuring substantially elevated Lewis acidity promoted the adsorption and activation of benzene. Consequently, the Mn/meso-CeO₂ catalyst exhibited a superior catalytic oxidation reactivity (T₉₀ = 215 °C) toward C₆H₆ combustion via a Langmuir–Hinshelwood mechanism. This work underlines the importance of rational design and regulation of catalytic sites over metal oxide surfaces for robust O₂ activation and durable refractory AVOC combustion.