Fabrication of ceramic components with hierarchical porosity

Abstract

This article reviews different methodologies for the fabrication of monolithic ceramic components possessing multiscale porosity, i.e., with pores ranging from a few nanometers to several hundred microns. Two main strategies have been discussed: (a) the assembling of micro/ mesoporous materials into components possessing also macropores; (b) the addition of micro/mesoporosity to macroporous, cellular monoliths. Both routes include onepot and multi-step processing routes, and yield components with different properties in terms, for instance, of specific surface area values, mechanical strength, and permeability to fluids. The wide range of processing approaches available enable the fabrication of components with very varied morphology, suitable for a variety of industrial applications

TiO2 nanocrystals grafted on macroporous silica: A novel hybrid organic–inorganic sol–gel approach for the synthesis of highly photoactive composite material

“…Different approaches, based on soft-chemistry routes, hydrothermal synthesis, and chemical (CVD)/physical (PVD) vapour deposition, were proposed in order to obtain oxide coatings on preformed macroporous ceramic matrices [23]. The ideal active layers should be homogeneous, chemically and thermally stable, loading large amounts of material crucial for the catalytic activity and without pore occlusion which limits the whole permeability.…”

Material Design for Metal Oxide Chemiresistive Gas Sensors

“…Various methods have been considered for synthesizing such hierarchical hollow-particle structures, including spray drying [59,60], sol-gel [61], layer-by-layer (LbL) templating [62,63], electrodeposition [64], vapor-phase impregnation [65], interface growth, pulse laser deposition, and others [66]. However, the most promising technologies seem to be methods based on sol-gel, aerosol spray and Sensitivity (R gas /R air or R gas /R air ); R-resistive; nw -nanowire; nt-naotube; nb-nanobelt; nr-nanoribbon LbL deposition [58].…”

Metal Oxide-Based Nanostructures

“…Various methods have been considered for synthesizing such hierarchical hollow-particle structures, including spray-drying (Okuyama et al 2006 ;Colombo et al 2010 ) , sol-gel (Hayashi et al 2009 ) , layer-by-layer (LbL) templating (Rothschild and Tuller 2006 ;Wang et al 2008 ) , electrodeposition (Wadea and Wegrowe 2005 ) , vapor-phase impregnation (Yue and Zhou 2008 ) , interface growth, and pulse laser deposition (Sanchez et al 2008 ) . However, the most promising technologies seem to be methods based on sol-gel, aerosol spray, and LbL deposition (Lee 2009 ) .…”