Fabrication of Efficient Hydrogenation Nanoreactors by Modifying the Freedom of Ultrasmall Platinum Nanoparticles within Yolk-Shell Nanospheres

The synthesis of silica-based yolk-shell nanospheres confined with ultrasmall platinum nanoparticles (Pt NPs) stabilized with poly(amidoamine), in which the interaction strength between Pt NPs and the support could be facilely tuned, is reported. By ingenious utilization of silica cores with different surface wettability (hydrophilic vs. -phobic) as the adsorbent, Pt NPs could be confined in different locations of the yolk-shell nanoreactor (core vs. hollow shell), and thus, exhibit different interaction strengths with the nanoreactor (strong vs. weak). It is interesting to find that the adsorbed Pt NPs are released from the core to the hollow interiors of the yolk-shell nanospheres when a superhydrophobic inner core material (SiO2Ph) is employed, which results in the preparation of an immobilized catalyst (Pt@SiO2Ph); this possesses the weakest interaction strength with the support and shows the highest catalytic activity (88500 and 7080h(-1) for the hydrogenation of cyclohexene and nitrobenzene, respectively), due to its unaffected freedom of Pt NPs for retention of the intrinsic properties.