title: In situ growth of catalytic active Au-Pt bimetallic nanorods in thermoresponsive core-shell microgels.
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.
authors.affiliation: F-I2 Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany. yan.lu@helmholtz-berlin.de
authors.forename: Yan
authors.initials: Y
authors.lastname: Lu
authors.forename: Jiayin
authors.initials: J
authors.lastname: Yuan
authors.forename: Frank
authors.initials: F
authors.lastname: Polzer
authors.forename: Markus
authors.initials: M
authors.lastname: Drechsler
authors.forename: Johannes
authors.initials: J
authors.lastname: Preussner
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D000180:Acrylic Resins; D002384:Catalysis; D005782:Gels; D006046:Gold / Q000737:chemistry*; D007700:Kinetics; D046529:Microscopy, Electron, Transmission; D055616:Microtechnology / Q000379:methods*; D043942:Nanotubes / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
chemical_list: D000178:Acrylamides; D000180:Acrylic Resins; D005782:Gels; D011108:Polymers; D011137:Polystyrenes; C052970:poly-N-isopropylacrylamide; D010984:Platinum; D006046:Gold; C021221:N,N'-methylenebisacrylamide