Synthesis of Pd-CoO Hybrid Nanostructure-Encapsulated Hollow Silica Nanospheres through Reverse Microemulsion Systems and Their Application as Efficient Hydrodechlorination Catalysts.

Pd-CoO heteroaggregate-encapsulated hollow porous silica nanoreactors (Pd-CoO@HPSNs) were synthesized by a reverse microemulsion system. The key design of the developed reverse microemulsion system is to use poly(ethyleneimine) in the water droplets as the void templates for silica deposition and for anchoring the catalytic functionality inside the hollow silica nanospheres. The synthesized Pd-CoO@HPSNs contain ∼3 nm Pd-CoO hybrid nanostructures in ∼10 nm central cavities of silica nanospheres and illustrated a significantly promoted efficiency for hydrodechlorination of a series of chlorophenols into phenols under mild reaction conditions. The catalytic enhancement of Pd-CoO@HPSNs is ascribed to the synergistic effect between Pd and CoO and the protection of silica shells to the inner catalytic functionality.