Mesoporous metal oxides with improved atomic ordering in the pore walls

Photocatalytic Activity of Structured Mesoporous TiO2 Materials

“…Titanium dioxide is the most important semiconductor with large potential in photocatalysis, solar cells, photochromism, sensoring, and other applications in nanothecnology. − For many of these applications, the porosity, surface area, structure, crystal phase, particle size, and presence of dopants are factors that influence dramatically the activity and performance of titanium dioxide. While in the past decade and particularly after the seminal contribution describing the preparation of MCM materials there has been considerable progress in the preparation of mesoporous structured silicates, progress in the synthesis of other metal oxides with analogous structure as that of porous silicas has been much more limited. − In contrast to the case of microporous solids and particularly titanosilicates such as a ETS-10, one of the major problems in the preparation of the mesoporous metal oxides is their poor stability collapsing their structure very easily under mild conditions. − A novel strategy consists of using as building blocks for the preparation of a mesoporous material, not a monomeric molecular metal precursor, but colloidal nanoparticles adequately stabilized by ligands that after templation with surfactants in the usual way employed for mesoporous silicas will form part of the pore walls. Synthesis and calcination with particle sinterization and formation of covalent bonds between these nanoparticles finally produce a material that is considerably more robust and thermally more stable than those prepared analogously from molecular precursors.…”