Direct hydrothermal synthesis of nanosized mesoporous ramsdellite manganese oxide with high surface area

We first synthesized nanosized mesoporous R-MnO2 using different block copolymers and PEG by direct hydrothermal synthesis method. The block copolymers seemed to play the important role. At appropriate synthesis conditions, the mesoporous R-MnO2 with high surface area, narrow pore size distributions and ordered structure with uniform mesopores could be obtained. The mesoporous R-MnO2 had nanoarrays with uniform mesopores (intercrystalline voids). Because the residual copolymer in the product could be easily removed by washing after synthesis, the calcination procedure of the final mesoporous R-MnO2 obtained was not necessary, suggesting that this method is economical and environmental. This direct hydrothermal synthesis method can potentially develop a new method for preparing other metal oxide. We think that the mesoporous R-MnO2 formed through a mechanism that combines PEO moieties in block polymers self-assembly with complication of Mn species. The mesoporous R-MnO2 had high thermal stability.

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► Mesoporous R-MnO2 could be obtained using the direct hydrothermal synthesis method.
► Mesoporous R-MnO2 had high surface area, narrow pore size distributions.
► Mesoporous R-MnO2 had uniform mesopores formed by nanoarrays (intercrystalline voids).
► The residual copolymer in the product could be easily removed by washing after synthesis.