Preparation and Characterization of Hierarchically Porous SiO_2@C@MnO_2 Monoliths

摘要

.Hierarchical porous SiO_2@C@MnO_2 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 MnO_2 was directly grown on the skeleton of SiO_2@C accompanied by redox reaction between C and KMnO_4. The effects of glucose and KMnO_4 concentrations, and hydrothermal reaction on the morphology of MnO_2 particles on the surface of SiO_2 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) KMnO_4 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 MnO_2 to some degree. The XPS spectra of SiO_2@C@MnO_2 is in good agreement with reported data in MnO_2- The crystal phase of MnO_2 was a-MnO_2 after thermal treatment at the temperature of 600癈 from the XRD patterns. Three-dimensional porous well-defined morphological SiO_2@C@MnO_2 be promising materials for the catalytic elimination of air pollutants since large quantities can be obtained from porous structure combined with a-MnO_2 equipped with high active performance.