Fully alloyed Ag/Au nanospheres: combining the plasmonic property of Ag with the stability of Au.

We report that fully alloyed Ag/Au nanospheres with high compositional homogeneity ensured by annealing at elevated temperatures show large extinction cross sections, extremely narrow bandwidths, and remarkable stability in harsh chemical environments. Nanostructures of Ag are known to have much stronger surface plasmon resonance than Au, but their applications in many areas have been very limited by their poor chemical stability against nonideal chemical environments. Here we address this issue by producing fully alloyed Ag/Au nanospheres through a surface-protected annealing process. A critical temperature has been found to be around 930 °C, below which the resulting alloy nanospheres, although significantly more stable than pure silver nanoparticles, can still gradually decay upon extended exposure to a harsh etchant. Nanospheres annealed above the critical temperature show a homogeneous distribution of Ag and Au, minimal crystallographic defects, and the absence of structural and compositional interfaces, which account for the extremely narrow bandwidths of the surface plasmon resonance and may enable many plasmonic applications with high performance and long lifetime, especially for those involving corrosive species.

[1]  Yadong Yin,et al.  One-step growth of triangular silver nanoplates with predictable sizes on a large scale. , 2014, Nanoscale.

[2]  Yadong Yin,et al.  Size-tailored synthesis of silver quasi-nanospheres by kinetically controlled seeded growth. , 2013, Langmuir : the ACS journal of surfaces and colloids.

[3]  Yadong Yin,et al.  Seeded growth route to noble metal nanostructures , 2013 .

[4]  C. Mottet,et al.  Effect of Alloying on the Optical Properties of Ag–Au Nanoparticles , 2013 .

[5]  Miaofang Chi,et al.  Highly stable silver nanoplates for surface plasmon resonance biosensing. , 2012, Angewandte Chemie.

[6]  Yiding Liu,et al.  One-step seeded growth of Au nanoparticles with widely tunable sizes. , 2012, Nanoscale.

[7]  S. Linic,et al.  Plasmonic-metal nanostructures for efficient conversion of solar to chemical energy. , 2011, Nature materials.

[8]  Claire M. Cobley,et al.  Controlling the synthesis and assembly of silver nanostructures for plasmonic applications. , 2011, Chemical reviews.

[9]  A. Oldenburg,et al.  Synthesis of Au(Core)/Ag(Shell) nanoparticles and their conversion to AuAg alloy nanoparticles. , 2011, Small.

[10]  M. Cortie,et al.  Synthesis and optical properties of hybrid and alloy plasmonic nanoparticles. , 2011, Chemical reviews.

[11]  Shaojun Guo,et al.  A facile and controllable strategy to synthesize Au-Ag alloy nanoparticles within polyelectrolyte multilayer nanoreactors upon thermal reduction. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[12]  Wei Zhang,et al.  Ultrasonic alloying of preformed gold and silver nanoparticles. , 2010, Small.

[13]  John M Kelly,et al.  Etching-resistant silver nanoprisms by epitaxial deposition of a protecting layer of gold at the edges. , 2009, Langmuir : the ACS journal of surfaces and colloids.

[14]  J. Lee,et al.  Synthesis of Monodisperse AgAu Alloy Nanoparticles with Independently Tunable Morphology, Composition, Size, and Surface Chemistry and Their 3‐D Superlattices , 2009 .

[15]  Shouheng Sun,et al.  Synthesis of AuAg alloy nanoparticles from core/shell-structured Ag/Au. , 2009, Small.

[16]  J. Wilcoxon.  Optical absorption properties of dispersed gold and silver alloy nanoparticles. , 2009, The journal of physical chemistry. B.

[17]  H. Yin,et al.  One-Pot Synthesis of Oleylamine Coated AuAg Alloy NPs and Their Catalysis for CO Oxidation , 2009 .

[18]  Marco Zanella,et al.  Biological applications of gold nanoparticles. , 2008, Chemical Society reviews.

[19]  P. Brevet,et al.  Surface heterogeneity in Au-Ag nanoparticles probed by hyper-Rayleigh scattering , 2008 .

[20]  Younan Xia,et al.  Gold nanocages: synthesis, properties, and applications. , 2008, Accounts of chemical research.

[21]  S. Devi,et al.  Preparation of Silver–Gold Alloy Nanoparticles at Higher Concentration Using Sodium Dodecyl Sulfate , 2008 .

[22]  Sarah J. Hurst,et al.  Self‐Assembled Monolayer Mediated Silica Coating of Silver Triangular Nanoprisms , 2007 .

[23]  Yun Tang,et al.  Tailoring properties and functionalities of metal nanoparticles through crystallinity engineering. , 2007, Nature materials.

[24]  Chris Boothroyd,et al.  Size and composition tunable Ag–Au alloy nanoparticles by replacement reactions , 2007 .

[25]  Jing Zhao,et al.  Ultrastable substrates for surface-enhanced Raman spectroscopy: Al2O3 overlayers fabricated by atomic layer deposition yield improved anthrax biomarker detection. , 2006, Journal of the American Chemical Society.

[26]  T. Walther,et al.  Laser-assisted synthesis of Au-Ag alloy nanoparticles in solution. , 2006, The journal of physical chemistry. B.

[27]  G. Hartland,et al.  Electronic dephasing in bimetallic gold-silver nanoparticles examined by single particle spectroscopy. , 2005, The journal of physical chemistry. B.

[28]  L. Liz‐Marzán,et al.  AuAg bimetallic nanoparticles: formation, silica-coating and selective etching. , 2004, Faraday discussions.

[29]  Philippe Guyot-Sionnest,et al.  Synthesis and Optical Characterization of Au/Ag Core/Shell Nanorods , 2004 .

[30]  D. Astruc,et al.  Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology. , 2004, Chemical reviews.

[31]  Catherine J. Murphy,et al.  Solution-Phase Synthesis of Sub-10 nm Au−Ag Alloy Nanoparticles , 2002 .

[32]  Charles F Vardeman,et al.  Size-dependent spontaneous alloying of Au-Ag nanoparticles. , 2002, Journal of the American Chemical Society.

[33]  Catherine J. Murphy,et al.  Seeding Growth for Size Control of 5−40 nm Diameter Gold Nanoparticles , 2001 .

[34]  A. Henglein,et al.  Laser-Induced Inter-Diffusion in AuAg Core−Shell Nanoparticles , 2000 .

[35]  M. El-Sayed,et al.  Spectral Properties and Relaxation Dynamics of Surface Plasmon Electronic Oscillations in Gold and Silver Nanodots and Nanorods , 1999 .

[36]  Mostafa A. El-Sayed,et al.  Alloy Formation of Gold−Silver Nanoparticles and the Dependence of the Plasmon Absorption on Their Composition , 1999 .

[37]  R. Murray,et al.  Stable, monolayer-protected metal alloy clusters [18] , 1998 .

[38]  Paul Mulvaney,et al.  Surface Plasmon Spectroscopy of Nanosized Metal Particles , 1996 .