Core-shell structures, representing multiple-discrete functions related components integrated in one unit, have recently been subjected to extensive research because they promise wide applications in renewable energy, advanced biomedicine, and environmental cleanup. The success of all these applications strongly depends on the availability of various shell frameworks with tunable composition, thickness and structures over well-designed functional cores. Up till now, a number of shell frameworks (e.g. semiconductors, noble metals, polymers) have been developed to pursue these aims.Recently, we first extend the classical St�ber method of hydrolysis and condensation of silicon alkoxides (e.g. TEOS) in ethanol/water mixtures under alkaline conditions (e.g. NH3) to construct mesoporous SiO2 shells using CTAB as a template on various substrates, such as superparamagnetic Fe3O4 microspheres, upconversion nanoparticles, ITO conductive glass, and so on. The resulted core-shell Fe3O4 microspheres show a high surface area, a large pore volume, and accessible mesopore channels. The mesoporous silica thin films grown from the St�ber method have uniform pore channels perpendicular to the substrate. It is interesting that the uniform mesoporous silica thin films can further be assembled to multi-layers arrays, showing promising applications in separation, catalysis and advanced devices. More recently, we demonstrate a versatile kinetics-controlled coating method to synthesize uniform core@TiO2 shell structures. To our knowledge, this is the first report on extending St�ber method to rationally control the hydrolysis and condensation of TBOT in ethanol/ammonia mixtures for constructing multifunctional core-shell structures with uniform porous TiO2 shells. In this case, the preferential heterogeneous nucleation and growth of TiO2 on the surface of cores (e.g. a-Fe2O3 ellipsoids, Fe3O4 spheres, SiO2spheres and GO nanosheets) can be realized by precisely controlling the reaction kinetics.

Uniform multifunctional porous core-shell structures from a simple Stöber method

245th National Meeting (2013)

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