Palladium infiltration in high surface area microporous silica nanoparticles

Metallic Pd clusters were embedded into a host matrix of microporous SiO2 nanoparticles via a solution reduction of Pd(NO3)2 by hydrazine hydrate. The infiltration of 33 wt.% Pd leads to a 13% porosity loss of SiO2 nanoparticles, which demonstrated an initial surface area of 748 m2/g. The presence of Pd in the pores was demonstrated by EDS spectroscopy and by X-ray diffraction. The metallic guest species presumably reside in the accessible micropores with an estimated size about 1.3 nm. Hydrogen uptake was measured for Pd-infiltrated SiO2 nanoparticles. A possible mechanism for the formation of composite nanoparticles is proposed based on electrostatic interaction between Pd2+ and SiO2 nanoparticles.