Monodisperse hollow spheres with sandwich heterostructured shells as high-performance catalysts via an extended SiO2 template method.

To improve and extend the SiO2 template method for preparing metal oxide hollow spheres, a general and facile "sol-gel and hydrothermal" method is developed to replace the current "sol-gel, calcination, and base-etching" processes for the construction of well-defined sandwich metal oxide@noble metal NP@metal oxide hollow spheres. As-synthesized hollow spheres exhibit high performances in various catalytic reactions.