Generation of abundant oxygen vacancies in Fe doped δ-MnO2 by a facile interfacial synthesis strategy for highly efficient catalysis of VOCs oxidation

•Fe doping via interfacial redox-precipitation method was effective to generate abundant oxygen vacancies over FeMn oxide catalysts.•Formation of abundant oxygen vacancies effectively improved oxygen species mobility and reducibility.•Rapid methyl dehydrogenation to form benzoate, and aromatic ring breakage are rate-controlling step for toluene oxidation.•Both adsorbed oxygen and lattice oxygen with improved mobility could participate in the toluene adsorption-oxidation process.•The oxygen vacancies could promote the CC breakage of aromatic ring.