Lu, Y.; Yuan, J.; Polzer, F.; Drechsler, M.; Preussner, J.: In Situ Growth of Catalytic Active Au-Pt Bimetallic Nanorods in Thermoresponsive Core-Shell Microgels. ACS Nano 4 (2010), p. 7078-7086
10.1021/nn102622d
Abstract:
Here, we demonstrate that bimetallic Au-Pt nanorods (NRs) can be grown in-situ into thermosensitive core-shell microgel particles by a novel two-step approach. In the first step, Au NRs with an average width of 6.6 ± 0.3 nm and length of 34.5 ± 5.2 nm (aspect ratio 5.2 ± 0.6) were homogeneously embedded into the shell of PNIPA networks. The volume transition of the microgel network leads to a strong red shift of the longitudinal plasmon band of the Au NRs. In the second step, platinum was preferentially deposited onto the tips of Au NRs to form dumbbell-shaped bimetallic nanoparticles. The novel synthesis forms bimetallic Au-Pt NRs immobilized in microgels without impeding their colloidal stability. Quantitative analysis of the catalytic activity for the reduction of 4-nitrophenol indicates that bimetallic Au-Pt NRs show highly enhanced catalytic activity, which is due to the synergistic effect of bimetallic nanoparticles. The catalytic activity of immobilized Au-Pt NRs can be modulated by the volume transition of thermosensitive microgels. This demonstrates that core-shell microgels are capable of serving as “smart nanoreactors” for the catalytic active bimetallic nanoparticles with controlled morphology and high colloidal stability.