turkevich synthesis method of citrate-capped gold nanoparticle seeds for element synthesis

Aqueous Synthesis of Plasmonic Gold-Tin Alloy Nanoparticles

Plasmonic metal nanoparticles1,2 have applications in catalysis, optoelectronics, sensing, and sustainability due to their ability to absorb light with great efficiency, concentrate light into sub-nanometer volumes, and enhance catalytic reactions3,4,5. Only a few metals display efficient localized surface plasmon resonances (LSPRs). Among them, one of the widely explored metals is Au3.
Au is an extensively studied noble metal known for its stable alloy formation with other metals. However, the Au LSPR is limited to the visible and infrared and cannot be tuned to higher energies6,7,8. Meanwhile, post-transition metals have a variety of interesting reactive and catalytic properties distinct from the noble metals6,9,10.&#160;By alloying Au with post-transition metals, the LSPR can be tuned toward higher energies toward the UV1.&#160;This protocol focuses on Au-Sn alloying. Sn is known to alloy readily with many metals, can have UV LSPRs, and has interesting catalytic applications, such as formic acid formation via carbon dioxide reduction6,7,8. Au and Sn alloys were synthesized using a seeded process through chemical reduction and diffusion of Sn into the seeds.
The primary goal of this method is to synthesize aqueous metal nanoparticle alloys quickly (i.e.,&#160;in a few hours) and reproducibly at the benchtop using aqueous chemistry. Initially, Au seeds are prepared using the Turkevich method11, followed by seed-based diffusion synthesis, a common strategy when forming random alloy nanoparticles8. Notably, alloying of Sn requires a relatively short time (~30 min) in a mild environment with simple equipment compared to other methods7,8 that require higher temperature, higher vacuum instrumentation, or hazardous solvents. This process can be performed in mild, aqueous conditions without the need for burdensome environmental controls.&#160;The resulting Au-Sn alloys have consistent morphology, size, shape, and optical properties that can be controlled by manipulating the Sn content.

Author Spotlight: Designing Sustainable Nanomaterials for Advancing Synthesis and Element Mixing

Our research focus is on designing and creating new kinds of nanomaterials that incorporate a wide variety of elements that impact major challenges in sustainability and in energy. A primary focus of this is understanding how to mix elements with distinct properties across the periodic table. Most syntheses for alloy metal nanoparticles require high temperatures, organic solvents, and we remove oxygen.Our synthesis works in mild conditions, in water, and on the bench top with mild heating. Our future research will focus on exploring the generalizability of this strategy to incorporate multiple elements into alloy nanoparticles while also controlling their size and their shape. These are crucial for unlocking new properties.

Turkevich Synthesis Method of Citrate-Capped Gold Nanoparticle Seeds for Element Synthesis

turkevich-synthesis-method-citrate-capped-gold-nanoparticle-seeds-for

Research

JoVE Journal

Chemistry

This protocol describes the synthesis of Au nanoparticle seeds and the subsequent formation of Au-Sn bimetallic nanoparticles. These nanoparticles have potential applications in catalysis, optoelectronics, imaging, and drug delivery. Previously, methods for producing alloy nanoparticles have been time-consuming, require complex reaction conditions, and can have inconsistent results. The outlined protocol first describes the synthesis of approximately 13 nm Au nanoparticle seeds using the Turkevich method. The protocol next describes the reduction of Sn and its incorporation into the Au seeds to generate Au-Sn alloy nanoparticles. The optical and structural characterization of these nanoparticles is described. Optically, prominent localized surface plasmon resonances (LSPRs) are apparent using UV-visible spectroscopy. Structurally, powder X-ray diffraction (XRD) reflects all particles to be less than 20 nm and shows patterns for Au, Sn, and multiple Au-Sn intermetallic phases. Spherical morphology and size distribution are obtained from transmission electron microscopy (TEM) imaging. TEM reveals that after Sn incorporation, the nanoparticles grow to approximately 15 nm in diameter.

Here, the synthesis of gold (Au) seeds is described using the Turkevich method. These seeds are then used to synthesize gold-tin alloy (Au-Sn) nanoparticles with tunable plasmonic properties.

This protocol describes the synthesis of Au nanoparticle seeds and the subsequent formation of Au-Sn bimetallic nanoparticles. These nanoparticles have ...