Mesoporous spherical silica encapsulating Pd nanoparticles prepared by CO2-induced mircoemulsion and catalytic application in Suzuki coupling reaction

The CO 2 -in-water (C/W) microemulsion was formed when the pressure of CO 2 was above 4.0   MPa and has been investigated in-situ via high-pressure UV/vis spectra. The spherical mesoporous silica was successfully synthesized in CO 2 -induced microemulsion. Uniform spherical silica with a diameter of 102   ±   15   nm can be obtained by using C/W microemulsion as a template. It was observed that the BET area and pore volume of the spherical silica were enlarged with increasing the pressure of CO 2 . Moreover, Pd nanoparticles (Pd NPs) were encapsulated inside the spherical mesoporous silica through one-pot approach. Owing to the particular core–shell structure, this catalyst showed excellent recyclability in the Suzuki coupling reaction when compared with conventional Pd/SiO 2 and Pd/C catalysts. The new strategy can be extended as a general approach to prepare other metal nanoparticles encapsulated in spherical mesoporous silica.