Tailoring porous structure, reducibility and Mn⁴⁺ fraction of ε-MnO₂ microcubes for the complete oxidation of toluene

3D architectures porous epsilon-type manganese dioxide (ε-MnO₂) microcubes (PEMD) are successfully prepared by a glucose-urea-assisted hydrothermal synthesis of MnCO₃-carbon composites followed by annealing. It turns out that urea essentially assists in building the cubic shape while glucose plays a crucial role to form carbon inside the microcrystals, which are latterly removed by annealing to generate the porous structure. As a result, ε-MnO₂ materials possessing extraordinary features including the high porosity, reducibility, lattice oxygen reactivity and Mn⁴⁺ fraction, are feasible tailored. These unique properties, all together, significantly improve the catalytic performances of complete oxidation of toluene. Thus, it is found that the optimal catalyst (manganese-glucose-urea ratio of 6-2-6) synthesized at 180 °C exhibits an excellent activity for the complete oxidation of toluene (T₉₀ = 243 °C, lower 10 °C than that of pristine ε-MnO₂) and stability up to 10 h.