Ordered meso- and macroporous binary and mixed metal oxides

A critical review is provided of the principles guiding the synthesis of meso- and macroporous metal oxides on multiple length scales in the presence of surfactant mesophases and colloidal arrays of monodisperse spheres, and correlations between the synthesis conditions and the properties of the resulting meso- and macroporous oxides, such as thermal stability, pore structure, elemental and nanophase compositions of the inorganic wall, etc. The thermal stability of meso-structured metal-oxide phases, in particular, is discussed in terms of charge-matching at the organic-inorganic interface, the strength of interactions between inorganic species and surfactant headgroups, the flexibility of the M-O-M bond angles in the constituent metal oxides, the Tammann temperature of the metal oxide, and the occurrence of redox reactions in the metal-oxide wall. The ordered meso- and macroporous transition-metal-oxide phases are highly promising for a range of potential applications in separations, chemical sensing, heterogeneous catalysis, microelectronics, and photonics as, respectively, insulating layers of low-dielectric-constant and photonic-bandgap materials. Furthermore, the functionalization of the internal pore surfaces in these materials and deposition of functional nanoparticles within the pores offer numerous new possibilities for molecular engineering of catalytic and other advanced nanostructured materials displaying quantum-confinement effects. The emerging catalytic applications of these novel metal-oxide phases are discussed in particular detail. (C) Wiley-VCH Verlag GmbH Co.