Synthesis of multifunctional metal- and metal oxide core@mesoporous silica shell structures by using a wet chemical approach.

We demonstrate a facile wet chemical approach for fabricating spherical metal/metal-oxide core@mesoporous silica shell hybrid nanoparticles with different core and shell thicknesses. Vertically aligned mesoporous silica (mSiO(2)) shells were fabricated over the pre-synthesized spherical SiO(2) nanoparticles through a three-step strategy: 1) synthesis of core materials, 2) covering the core with an organic-inorganic composite layer, and 3) removing the organic template through calcinations in air. The mechanisms of hybrid structure formation are proposed. The multifunctional nature of the hybrid structures could be induced by incorporating guest ions/molecules, such as Ag, Mn, and TiO(2), into the pores of an mSiO(2) shell. Mn and TiO(2) cluster-incorporated composite structures have been tested to be antioxidizing agents and effective photocatalysts through electron spin resonance, radical scavenging tests, and the photocatalytic degradation of rhodamine B. The possibility of incorporating several hetero-element guest clusters in these mesoporous composite particles makes them highly attractive for multifunctional applications.