Preparation and Characterization of Hierarchically Porous SiO2@C@MnO2 Monoliths

Hierarchical porous SiO2@C@MnO2 monoliths have been fabricated by two step approaches: Elemental carbon was covered the internal surface of porous silica monoliths with impregnation and carbonized in inert atmosphere, and MnO2 was directly grown on the skeleton of SiO2@C accompanied by redox reaction between C and KMnO4. The effects of glucose and KMnO4 concentrations, and hydrothermal reaction on the morphology of MnO2 particles on the surface of SiO2 monoliths were investigated in detail. The results showed that the optimal factors of reaction condition involved 0.08 mol·L-1 glucose solution, 0.03 mol·L-1 KMnO4 solution and the reaction time of 5 h. SEM images and BET results indicated that the macroporous structure of the as-prepared material was preserved after modification, while the specific surface area and pore volume decreased with increasing amount of MnO2 to some degree. The XPS spectra of SiO2@C@MnO2 is in good agreement with reported data in MnO2. The crystal phase of MnO2 was α-MnO2 after thermal treatment at the temperature of 600 °C from the XRD patterns. Three-dimensional porous well-defined morphological SiO2@C@MnO2 be promising materials for the catalytic elimination of air pollutants since large quantities can be obtained from porous structure combined with α-MnO2 equipped with high active performance.