Hybrid Gold Architectures for Sensing and Catalytic Applications
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1176-Y07-07
Hybrid Gold Architectures for Sensing and Catalytic Applications Hyunjoon Song Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon, 305701, Republic of Korea
ABSTRACT Exquisite control of surface functionality is essential to tailor the chemical and physical properties of metal nanocrystals to the requirements of specific applications. Hybridization of gold nanoparticles with other components such as polymers and metal oxides can effectively introduce appropriate functionalities on the surface without changing their own properties, and thereby become a basic architecture for various applications such as sensors and catalysts. In the present work, we report two hybrid nanostructures comprising gold nanocrystals. PDMAEMA (poly(dimethylaminoethylmethacrylate))–gold hybrid nanocrystals were synthesized via a polyol process, which produced carboxylate functionality on the gold surface. This hybrid structure was employed for a sensitive pH-sensor in solution. On the other hand, porous silica-gold hybrid nanoreactors were produced by selective etching of gold cores from gold@silica core-shell particles. The nanoreactor framework exhibited high and controllable activity on the reduction of aromatic nitroxides. These two examples of hybrid gold architectures would be able to apply for other metal and metal oxide systems to develop biosensors and energy production catalysts.
INTRODUCTION Morphology control of gold nanocrystals has been of major interest due to their intriguing structure-property relations in various diameter ranges [1]. Color changes are readily observed in gold nanoparticles with different size and shape in ~ 100 nm diameters. Tiny gold nanoparticles in several nanometer diameters are one of the best catalysts for low temperature oxidation of hydrocarbons. In order to employ the gold nanostructures for specific applications, appropriate functionality must be introduced on the nanocrystal surface to fit their physical and chemical properties to the requirements of applications [2]. Herein, we introduce two hybrid nanostructures including polymer-gold nanocrystals and silica-gold nanoreactors, and their uses for pH sensors and reaction catalysts. These hybrid architectures are expected to expand the utility of gold nanocrystals to a variety of applications, such as photonics, electronics, biosensing and imaging, and catalysis. EXPERIMENT Synthesis of PDMAEMA-gold hybrid nanocrystals A PD (1,5-pentanediol, 96%, Aldrich) solution of PDMAEMA (0.10 mL, 0.15 M, Mw = 50,000, Polyscience) was added to boiling PD (5.0 mL). Immediately, a PD solution of HAuCl4 (0.2 mL, 0.005 M, 99.9+%, Aldrich) was added, and the resulting mixture was refluxed for 5 h.
The hybrid particles were precipitated by centrifugation, and thoroughly washed with ethanol in a precipitation/dispersion cycle. Synthesis of porous silica-gold hybrid nanoreactors Colloidal gold nanoparticles and gold@silica core-shell particles were prepared by a modified polyol process and the Stöber method according
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