Controllable redox-induced in-situ growth of MnO2 over Mn2O3 for toluene oxidation: Active heterostructure interfaces

Mn-based heterostructure catalysts show great potential for catalytic oxidation of toluene owing to the unique properties of their hetero-interfaces. Herein, we tailored the MnO2 heteroepitaxy over Mn2O3 to achieve well-defined morphology and constructed clean MnO2-Mn2O3 heterostructure interfaces by H+/KMnO4 treatment. The T-0.5 catalyst (treating duration of 0.5 h) gave the highest activity and good stability. The interface enhanced the reducibility and oxygen storage capacity compared with pure Mn2O3. Surface reconstruction and metastable facets exposure were observed after the H+/KMnO4 treatment, leading to the easy-release of lattice oxygen. Additionally, abundant oxygen vacancies and redundant coordination lattice oxygen were observed at the MnO2 and Mn2O3 sides of the hetero-interface, respectively. These features provided ample oxygen adspecies and increased lattice oxygen mobility. The interface-related oxygen vacancies facilitated methyl dehydrogenation and demethylation of adsorbed toluene. The redundant coordination lattice oxygen contributed to the enhanced aromatic ring breakage capability.