This work was partly supported by Nippon Sheet Glass Foundation for Materials Science and Engineering and JSPS KAKENHI (Grant-in-Aid for Challenging Exploratory Research, #50362281).

Caution: Always use caution when working with chemicals and solutions. Follow the appropriate safety practices and wear gloves, glasses, and a lab coat at all times. Be aware that nanomaterials may have additional hazards as compared to their bulk counterpart.
1. Preparation of Regents
<ol>
	<li>Prepare the methyl viologen aqueous solution by dissolving 0.0012 g of 1,1&#39;-dimethyl-4,4&#39;-bipyridinium dichloride (methyl viologen; MV2+) in 20 ml of water to give 0.2 mM MV2+.</li>
	<li>Prepare the gold(III) chloride aqueous solution by dissolving 0.1050 g of gold(III) tetrachloride trihydrate (HAuCl4&#8226; 3H2O) in 10 ml of water to give 25 mM HAuCl4.</li>
	<li>Prepare the sodium borohydride aqueous solution by dissolving 0.03844 g of sodium tetrahydroborate (NaBH4) in 10 ml of water to give 100 mM NaBH4.</li>
	<li>Prepare the 2-ammoniumethanethiol aqueous solution by dissolving 0.2985 g of 2-ammoniumethanethiol chloride salt (2-AET+) in 25 ml of water to give 100 mM 2-AET+.</li>
</ol>
2. Synthesis of TNS Colloidal Suspensions
NOTE: Titania nanosheets (TNS; Ti0.91O2) were prepared according to the well-established procedure reported previously22,23,30.
<ol>
	<li>Prepare the starting material of layered cesium titanate Cs0.7Ti1.825O4 by calcining a stoichiometric mixture of Cs2CO3 (0.4040 g) and TiO2 (ST-01; 0.5000 g) at 800 &#176;C for 20 hr22. Repeat this twice.</li>
	<li>Prepare the protonated layered titanate (H0.7Ti1.825O4&#183;H2O) by repeatedly treating 0.8142 g of cesium titanate with an HCl (100 mM, 81.42 ml) aqueous solution by using a shaker (300 Hz) for 12 hr.</li>
	<li>Prepare the exfoliated layered titanate (TNS) colloidal suspensions by stirring the protonated titanate powder (0.0998 g) vigorously (500 rpm) with 25 ml of a 17 mM tetrabutylammonium hydroxide (TBA+ OH&#8722;) aqueous solution for about 2 weeks at ambient temperature under dark conditions. The resulting opalescent suspension contains exfoliated titania nanosheets (TNS; 1.4 g/L, pH = 11~12).</li>
</ol>
3. Synthesis of TNS Films21
<ol>
	<li>Preparation of TNS cast films (c-TNS)
	<ol>
		<li>Pre-clean glass substrates (~20 x 20 mm2) through ultrasonic treatments using an ultrasonic cleaner (27 kHz) in 1 M aqueous sodium hydroxide (NaOH) for 30 min.</li>
		<li>Rinse the substrates with 5-10 mL of ultrapure water (&#60;0.056 &#181;S cm-1).</li>
		<li>Dip a glass substrate in a 0.1 M aqueous hydrochloric acid (HCl) for 3 min and rinse with 5-10 ml of ultrapure water.</li>
		<li>Clean the substrates through ultrasonic treatments (27 kHz) in pure water for 1 hr, and then rinse with pure water. Dry with a hairdryer for 2-3 min (until dry).</li>
		<li>Cast the colloidal suspension of TNS on the glass substrate in 300 &#181;l aliquots.</li>
		<li>Dry at 60 &#176;C for 2 hr using a dry oven to give the c-TNS film.</li>
	</ol>
	</li>
	<li>Preparation of Sintered TNS Film (s-TNS)
	<ol>
		<li>To achieve thermal fixation of the TNS components on the glass substrate (s-TNS film), sinter the obtained c-TNS film in air at 500 &#176;C for 3 hr (heating from 25 to 500 &#176;C at a rate of 6.8 &#176;C/min) using the oven.</li>
		<li>Repeat the sintering process twice.</li>
	</ol>
	</li>
	<li>Preparation of Films
	<ol>
		<li>When the s-TNS films are immersed in solution, position the deposited s-TNS film so that it faces the top for all experimental procedures.</li>
		<li>Carry out all experiments under dark conditions by covering the setup with aluminum foil to avoid the photoreaction of TNS.</li>
	</ol>
	</li>
	<li>Preparation of Methyl Viologen (MV2+) Intercalated TNS Films (TNS/MV2+)
	<ol>
		<li>Immerse an s-TNS film in an aqueous solution of MV2+ dichloride salt (0.2 mM, 3 ml) in a Petri dish for 7 h at room temperature (RT) under dark conditions.</li>
		<li>Rinse the obtained samples with ultrapure water (5-10 ml) and dry in air at 60 &#176;C using an oven in the dark for ~1 hr.</li>
	</ol>
	</li>
	<li>Preparation of Au(III) Intercalated TNS Films (TNS/Au(III))
	<ol>
		<li>Immerse a TNS/MV2+ film in an aqueous solution of HAuCl4 (25 mM, 3 ml) in a Petri dish for 3 hr at RT under dark conditions.</li>
		<li>Rinse the obtained samples with ultrapure water (5-10 ml) and dry in air at 60 &#176;C using an oven in the dark for ~1 hr.</li>
	</ol>
	</li>
	<li>Synthesis of AuNP within the Interlayer Space of TNS Films (TNS/AuNP)
	<ol>
		<li>Immerse a TNS/Au(III) film in an aqueous solution of NaBH4 (0.1 M, 5 ml) in a Petri dish for 0.5 hr at RT under dark conditions.</li>
		<li>Dry the obtained films in air at 60 &#176;C using an oven in the dark for ~1 hr.</li>
	</ol>
	</li>
	<li>Preparation of 2-AET+ Intercalated TNS Films (TNS/2-AET+)
	<ol>
		<li>Immerse an s-TNS film in an aqueous solution of 2-AET+ Cl&#8722; (0.1 M, 3 ml) in a Petri dish for 24 hr at RT.</li>
		<li>Rinse obtained films with ultrapure water (5-10 ml) and dry in air at 60 &#176;C using an oven in the dark for ~1 hr.</li>
	</ol>
	</li>
	<li>Au(III) and 2-AET+ Co-Intercalated TNS Films (TNS/2-AET+/Au(III)).
	<ol>
		<li>Immerse a TNS/2-AET+ film in an aqueous solution of HAuCl4 (25 mM, 3 ml) for 3 h at RT.</li>
		<li>Rinse the obtained films with ultrapure water (5-10 ml) and dry in air at 60 &#176;C using an oven in the dark for ~1 hr.</li>
	</ol>
	</li>
	<li>Synthesis of AuNP within the Interlayer Space of TNS/2-AET+ Films (TNS/2-AET+/AuNP).
	<ol>
		<li>Immerse a TNS/2-AET+/Au(III) film in an aqueous solution of NaBH4 (0.1 M, 5 ml) in a Petri dish for 0.5 hr at RT under dark conditions.</li>
		<li>Rinse the obtained films with ultrapure water (5-10 ml) and dry in air at 60 &#176;C using oven in the dark for ~1 hr.</li>
	</ol>
	</li>
	<li>Characterizations
	<ol>
		<li>Carry out X-ray diffraction (XRD) analyses21 using a desktop X-ray diffractometer with monochromatized Cu-K&#945; radiation (&#955; = 0.15405 nm), operated at 30 kV and 15 mA.</li>
		<li>Take energy dispersive X-ray spectrometry (EDS) spectra21.</li>
		<li>Employ a multichannel photodetector or steady-state ultraviolet-visible (UV-Vis) absorption spectrophotometer to record UV-Vis absorption spectra for the prepared samples using transmittance mode21.</li>
	</ol>
	</li>
</ol>

We have nothing to disclose.

This manuscript provides a detailed protocol for the in situ synthesis of gold nanoparticles (AuNPs) within the interlayer space of TNS films. This is the first report of the in situ synthesis of AuNPs within the interlayer space of TNS. Moreover, we found that the 2-AET+ works as an effective protective reagent for AuNPs within the interlayer of TNS. These methods hybridized AuNPs and TNS transparent films. TNS films with good optical transparency21 were synthesized through sinter...

Various noble metal nanoparticles (MNPs) exhibit characteristic colors or tones due to their localized surface plasmon resonance (LSPR) properties; thus, MNPs can be used in various optical and/or photochemical applications1-4. Recently, combinations of metal oxide semiconductor (MOS) photocatalysts, such as titanium oxide (TiO2) and MNPs, have been thoroughly investigated as new types of photocatalysts5-14. However, in many cases, very small amounts of MNPs exist on the MOS surface, because most MOS particles have relatively low surface areas. On the other hand, layered metal oxide semiconductors (LMOSs) exhibit photocatalytic properties and have a large surface area, typically several hundred square meters per unit g of an LMOS15-17. In addition, various LMOSs have intercalation properties (i.e., various chemical species can be accommodated within their expandable and large interlayer spaces)15-20. Thus, with a combination of MNPs and LMOSs, it is expected that relatively large amounts of MNPs are hybridized with the semiconductor photocatalysts.
We have reported the first in situ synthesis of copper nanoparticles (CuNPs)21 within the interlayer space of LMOS (titania nanosheet; TNS16-30) transparent films through very simple steps. However, the details of the synthetic procedures and the characterization of the other noble MNPs and TNS hybrids have not yet been reported. Moreover, the CuNPs within the TNS layers were easily oxidized and decolorized under ambient conditions21. As such, we focused on gold nanoparticles (AuNPs), because AuNPs are widely used for various optical, photochemical, and catalytic applications, and it is expected that they will be relatively stable against oxidation3-5,7,8,10-14,28,31,32. Here, we report the synthesis of AuNPs within the interlayer space of TNS and show that 2-ammoniumethanethiol (2-AET+; Figure 1 inset) works effectively as a protective reagent for AuNPs within the interlayer of TNS.

<table><tbody><tr><td>Methyl viologen dichloride</td><td>Aldrich Chemical&amp;nbsp; Co., Inc.</td><td>1910-42-5</td><td></td></tr><tr><td>Tetrabutylammonium hydroxide</td><td>TCI</td><td>T1685</td><td></td></tr><tr><td>cesium carbonate</td><td>Kanto Chemical Co., Inc.</td><td>07184-33</td><td></td></tr><tr><td>anatase titanium dixoide</td><td>Ishihara Sangyo Ltd.</td><td>ST-01</td><td></td></tr><tr><td>hydrochloric acid</td><td>Junsei Chemical Co., Ltd.</td><td>20010-0350</td><td></td></tr><tr><td>sodium hydroxide</td><td>Junsei Chemical Co., Ltd.</td><td>195-13775</td><td></td></tr><tr><td>Tetrachloroauric(III) acid trihydrate</td><td>Kanto Chemical Co., Inc.</td><td>17044-60</td><td></td></tr><tr><td>sodium tetrahydroborate</td><td>Junsei Chemical Co., Ltd.</td><td>39245-1210</td><td></td></tr><tr><td>2-ammoniumethanethiol hydrochloride</td><td>TCI</td><td>A0296</td><td></td></tr><tr><td>Ultrapure water (0.056 &amp;micro;S/cm)</td><td></td><td></td><td>Milli-Q water purification system (Direct-Q&lt;sup&gt;&amp;reg;&lt;/sup&gt; 3UV, Millipore)</td></tr><tr><td>Microscope slide (Thickness: 1.0&amp;#8211;1.2 mm)</td><td>Matsunami glass Co., Ltd.</td><td></td><td></td></tr></tbody></table>

in situ synthesis of gold nanoparticles without aggregation in the interlayer space of layered titanate transparent films

Combinations of metal oxide semiconductors and gold nanoparticles (AuNPs) have been investigated as new types of materials. The in situ synthesis of AuNPs within the interlayer space of semiconducting layered titania nanosheet (TNS) films was investigated here. Two types of intermediate films (i.e., TNS films containing methyl viologen (TNS/MV2+) and 2-ammoniumethanethiol (TNS/2-AET+)) were prepared. The two intermediate films were soaked in an aqueous tetrachloroauric(III) acid (HAuCl4) solution, whereby considerable amounts of Au(III) species were accommodated within the interlayer spaces of the TNS films. The two types of obtained films were then soaked in an aqueous sodium tetrahydroborate (NaBH4) solution, whereupon the color of the films immediately changed from colorless to purple, suggesting the formation of AuNPs within the TNS interlayer. When only TNS/MV2+ was used as the intermediate film, the color of the film gradually changed from metallic purple to dusty purple within 30 min, suggesting that aggregation of AuNPs had occurred. In contrast, this color change was suppressed by using the TNS/2-AET+ intermediate film, and the AuNPs were stabilized for over 4 months, as evidenced by the characteristic extinction (absorption and scattering) band from the AuNPs.

Two types of precursor films were used in this study (i.e., with and without the protective reagent (2-AET+) within the interlayer of TNS). In the absence of 2-AET+, 1,1&#39;-dimethyl-4,4&#39;-bipyridinium dichloride (methyl viologen; MV2+) was used as an expander of the interlayer space, because MV2+-containing LMOSs have been frequently used as intermediates in the guest exchange method for preparing LMOSs16,17,21,33-36.</p...

Watch this Scientific Journal Video about In Situ Synthesis of Gold Nanoparticles without Aggregation in the Interlayer Space of Layered Titanate Transparent Films at JoVE.com

In Situ Synthesis of Gold Nanoparticles without Aggregation in the Interlayer Space of Layered Titanate Transparent Films

Here, we present a protocol for the in situ synthesis of gold nanoparticles (AuNPs) within the interlayer space of layered titanate films without the aggregation of AuNPs. No spectral change was observed even after 4 months. The synthesized material has expected applications in catalysis, photo-catalysis, and the development of cost-effective plasmonic devices.

In Situ Synthesis of Gold Nanoparticles without Aggregation in the Interlayer Space of Layered Titanate Transparent Films

Combinations of metal oxide semiconductors and gold nanoparticles (AuNPs) have been investigated as new types of materials. The in situ synthesis of AuNPs ...

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8.1K Views.  Niigata University. Here, we present a protocol for the in situ synthesis of gold nanoparticles (AuNPs) within the interlayer space of layered titanate films without the aggregation of AuNPs. No spectral change was observed even after 4 months. The synthesized material has expected applications in catalysis, photo-catalysis, and the development of cost-effective plasmonic devices.

Video: In Situ Synthesis of Gold Nanoparticles without Aggregation in the Interlayer Space of Layered Titanate Transparent Films

Template Directed Synthesis of Plasmonic Gold Nanotubes with Tunable IR Absorbance

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments1, 2. Applications of anodic aluminum oxide (AAO) membranes have been under development since the 1990's and have become a common method to template the synthesis of high aspect ratio nanostructures, mostly by electrochemical growth or pore-wetting. Recently, these membranes have become commercially available in a wide range of pore sizes and densities, leading to an extensive library of functional nanostructures being synthesized from AAO membranes. These include composite nanorods, nanowires and nanotubes made of metals, inorganic materials or polymers 3-10. Nanoporous membranes have been used to synthesize nanoparticle and nanotube arrays that perform well as refractive index sensors, plasmonic biosensors, or surface enhanced Raman spectroscopy (SERS) substrates 11-16, as well as a wide range of other fields such as photo-thermal heating 17, permselective transport 18, 19, catalysis 20, microfluidics 21, and electrochemical sensing 22, 23. Here, we report a novel procedure to prepare gold nanotubes in AAO membranes. Hollow nanostructures have potential application in plasmonic and SERS sensing, and we anticipate these gold nanotubes will allow for high sensitivity and strong plasmon signals, arising from decreased material dampening 15.

Solution-suspendable gold nanotubes with controlled dimensions can be synthesized by electrochemical deposition in porous anodic aluminum oxide (AAO) membranes using a hydrophobic polymer core. Gold nanotubes and nanotube arrays hold promise for applications in plasmonic biosensing, surface-enhanced Raman spectroscopy, photo-thermal heating, ionic and molecular transport, microfluidics, catalysis and electrochemical sensing.

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments1, 2. Applications of anodic aluminum oxide (AAO) ...

Chemistry

Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas allows the deposition of metal oxides with tunable morphology, structure, density and stoichiometry by a proper control of the plasma plume expansion dynamics. Such versatility can be exploited to produce nanostructured films from compact and dense to nanoporous characterized by a hierarchical assembly of nano-sized clusters. In particular we describe the detailed methodology to fabricate two types of Al-doped ZnO (AZO) films as transparent electrodes in photovoltaic devices: 1) at low O2 pressure, compact films with electrical conductivity and optical transparency close to the state of the art transparent conducting oxides (TCO) can be deposited at room temperature, to be compatible with thermally sensitive materials such as polymers used in organic photovoltaics (OPVs); 2) highly light scattering hierarchical structures resembling a forest of nano-trees are produced at higher pressures. Such structures show high Haze factor (&gt;80%) and may be exploited to enhance the light trapping capability. The method here described for AZO films can be applied to other metal oxides relevant for technological applications such as TiO2, Al2O3, WO3 and Ag4O4.

We describe the experimental method to deposit nanostructured oxide thin films by nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas. By using this method Al-doped ZnO (AZO) films, from compact to hierarchically structured as nano-tree forests, can be deposited.

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

A Technique to Functionalize and Self-assemble Macroscopic Nanoparticle-ligand Monolayer Films onto Template-free Substrates

This protocol describes a self-assembly technique to create macroscopic monolayer films composed of ligand-coated nanoparticles1,2. The simple, robust and scalable technique efficiently functionalizes metallic nanoparticles with thiol-ligands in a miscible water/organic solvent mixture allowing for rapid grafting of thiol groups onto the gold nanoparticle surface. The hydrophobic ligands on the nanoparticles then quickly phase separate the nanoparticles from the aqueous based suspension and confine them to the air-fluid interface. This drives the ligand-capped nanoparticles to form monolayer domains at the air-fluid interface.&#160; The use of water-miscible organic solvents is important as it enables the transport of the nanoparticles from the interface onto template-free substrates.&#160; The flow is mediated by a surface tension gradient3,4 and creates macroscopic, high-density, monolayer nanoparticle-ligand films.&#160; This self-assembly technique may be generalized to include the use of particles of different compositions, size, and shape and may lead to an efficient assembly method to produce low-cost, macroscopic, high-density, monolayer nanoparticle films for wide-spread applications.

A simple, robust and scalable technique to functionalize and self-assemble macroscopic nanoparticle-ligand monolayer films onto template-free substrates is described in this protocol.

This protocol describes a self-assembly technique to create macroscopic monolayer films composed of ligand-coated nanoparticles1,2. The simple, robust and ...

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

Synthesis, Assembly, and Characterization of Monolayer Protected Gold Nanoparticle Films for Protein Monolayer Electrochemistry

Colloidal gold nanoparticles protected with alkanethiolate ligands called monolayer protected gold clusters (MPCs) are synthesized and subsequently incorporated into film assemblies that serve as adsorption platforms for protein monolayer electrochemistry (PME). PME is utilized as the model system for studying electrochemical properties of redox proteins by confining them to an adsorption platform at a modified electrode, which also serves as a redox partner for electron transfer (ET) reactions. Studies have shown that gold nanoparticle film assemblies of this nature provide for a more homogeneous protein adsorption environment and promote ET without distance dependence compared to the more traditional systems modified with alkanethiol self-assembled monolayers (SAM).1-3 In this paper, MPCs functionalized with hexanethiolate ligands are synthesized using a modified Brust reaction4 and characterized with ultraviolet visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and proton (1H) nuclear magnetic resonance (NMR). MPC films are assembled on SAM modified gold electrode interfaces by using a "dip cycle" method of alternating MPC layers and dithiol linking molecules. Film growth at gold electrode is tracked electrochemically by measuring changes to the double layer charging current of the system. Analogous films assembled on silane modified glass slides allow for optical monitoring of film growth and cross-sectional TEM analysis provides an estimated film thickness. During film assembly, manipulation of the MPC ligand protection as well as the interparticle linkage mechanism allow for networked films, that are readily adaptable, to interface with redox protein having different adsorption mechanism. For example, Pseudomonas aeruginosa azurin (AZ) can be adsorbed hydrophobically to dithiol-linked films of hexanethiolate MPCs and cytochrome c (cyt c) can be immobilized electrostatically at a carboxylic acid modified MPC interfacial layer. In this report, we focus on the film protocol for the AZ system exclusively. Investigations involving the adsorption of proteins on MPC modified synthetic platforms could further the understanding of interactions between biomolecules and man-made materials, and consequently aid the development of biosensor schemes, ET modeling systems, and synthetic biocompatible materials.5-8

Alkanethiolate stabilized gold colloids known as monolayer protected clusters (MPCs) are synthesized, characterized, and assembled into thin films as an adsorption interface for protein monolayer electrochemistry of simple redox protein like Pseudomonas aeruginosa azurin (AZ) and cytochrome c (cyt c).

Colloidal gold nanoparticles protected with alkanethiolate ligands called monolayer protected gold clusters (MPCs) are synthesized and subsequently ...

Bioengineering

Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties of the materials were investigated. We used a one pot sol-gel approach to intercalate gold nano particles in the walls of mesoporous silica. To start with the synthesis, P123 was used as template to form micelles. Then TESPTS was used as a surface modification agent to intercalate gold nano particles. Following this process, TEOS was added in as a silica source which underwent a polymerization process in acid environment. After hydrothermal processing and calcination, the final product was acquired. Several techniques were utilized to characterize the porosity, morphology and structure of the gold intercalated mesoporous silica. The results showed a stable structure of mesoporous silica after gold intercalation. Through the oxidation of benzyl alcohol as a benchmark reaction, the GMS materials showed high selectivity and recyclability.

Here, we present a protocol with a sol-gel process to synthesize gold intercalated in the walls of mesoporous materials (GMS), which is confirmed to possess a mesoporous matrix with gold intercalated in the walls imparting great stability and recyclability.

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties ...

Synthesis and Reaction Chemistry of Nanosize Monosodium Titanate

This paper describes the synthesis and peroxide-modification of nanosize monosodium titanate (nMST), along with an ion-exchange reaction to load the material with Au(III) ions. The synthesis method was derived from a sol-gel process used to produce micron-sized monosodium titanate (MST), with several key modifications, including altering reagent concentrations, omitting a particle seed step, and introducing a non-ionic surfactant to facilitate control of particle formation and growth. The resultant nMST material exhibits spherical-shaped particle morphology with a monodisperse distribution of particle diameters in the range from 100 to 150&#160;nm. The nMST material was found to have a Brunauer-Emmett-Teller (BET) surface area of 285 m2g-1, which is more than an order of magnitude higher than the micron-sized MST. The isoelectric point of the nMST measured 3.34 pH units, which is a pH unit lower than that measured for the micron-size MST. The nMST material was found to serve as an effective ion exchanger under weakly acidic conditions for the preparation of an Au(III)-exchange nanotitanate. In addition, the formation of the corresponding peroxotitanate was demonstrated by reaction of the nMST with hydrogen peroxide.

The surfactant mediated sol-gel synthesis of nanosized monosodium titanate is described, along with preparation of the corresponding peroxide modified material. An ion-exchange reaction with Au(III) is also presented.

This paper describes the synthesis and peroxide-modification of nanosize monosodium titanate (nMST), along with an ion-exchange reaction to load the ...

A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like oligomeric clusters of these yellow nanoparticles of narrow size distribution are synthesized under ambient conditions via two methods. The delay-time method controls the number of subunits in the oligoclusters by varying the time between the addition of HAuCl4 to alkaline solution and the subsequent addition of reducing agent, NaSCN. The yellow oligoclusters produced range in size from ~3 to ~25 nm. This size range can be further extended by an add-on method utilizing hydroxylated gold chloride (Na+[Au(OH4-x)Clx]-) to auto-catalytically increase the number of subunits in the as-synthesized oligocluster nanoparticles, providing a total range of 3 nm to 70 nm. The crude oligocluster preparations display narrow size distributions and do not require further fractionation for most purposes. The oligoclusters formed can be concentrated &#62;300 fold without aggregation and the crude reaction mixtures remain stable for weeks without further processing. Because these oligomeric clusters can be concentrated before derivatization they allow expensive derivatizing agents to be used economically. In addition, we present two models by which predictions of particle size can be made with great accuracy.

We describe a simple method for producing highly stable oligomeric clusters of gold nanoparticles via the reduction of chloroauric acid (HAuCl4) with sodium thiocyanate (NaSCN). The oligoclusters have a narrow size distribution and can be produced with a wide range of sizes and surface coats.

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like ...

Fabrication of Periodic Gold Nanocup Arrays Using Colloidal Lithography

Within recent years, the field of plasmonics has exploded as researchers have demonstrated exciting applications related to chemical and optical sensing in combination with new nanofabrication techniques. A plasmon is a quantum of charge density oscillation that lends nanoscale metals such as gold and silver unique optical properties. In particular, gold and silver nanoparticles exhibit localized surface plasmon resonances-collective charge density oscillations on the surface of the nanoparticle-in the visible spectrum. Here, we focus on the fabrication of periodic arrays of anisotropic plasmonic nanostructures. These half-shell (or nanocup) structures can exhibit additional unique light-bending and polarization-dependent optical properties that simple isotropic nanostructures cannot. Researchers are interested in the fabrication of periodic arrays of nanocups for a wide variety of applications such as low-cost optical devices, surface-enhanced Raman scattering, and tamper indication. We present a scalable technique based on colloidal lithography in which it is possible to easily fabricate large periodic arrays of nanocups using spin-coating and self-assembled commercially available polymeric nanospheres. Electron microscopy and optical spectroscopy from the visible to near-infrared (near-IR) was performed to confirm successful nanocup fabrication. We conclude with a demonstration of the transfer of nanocups to a flexible, conformal adhesive film.

We demonstrate the fabrication of periodic gold nanocup arrays using colloidal lithographic techniques and discuss the importance of nanoplasmonic films.

Within recent years, the field of plasmonics has exploded as researchers have demonstrated exciting applications related to chemical and optical sensing ...

Growth of Gold Dendritic Nanoforests on Titanium Nitride-coated Silicon Substrates

In this study, a high-power impulse magnetron sputtering system is used to coat a flat and firm titanium nitride (TiN) film on silicon (Si) wafers, and a fluoride-assisted galvanic replacement reaction (FAGRR) is employed for the rapid and easy deposition of gold dendritic nanoforests (Au DNFs) on the TiN/Si substrates. Scanning electron microscopy (SEM) images and energy-dispersive X-ray spectroscopy patterns of TiN/Si and Au DNFs/TiN/Si samples validate that the synthesis process is accurately controlled. Under the reaction conditions in this study, the thickness of the Au DNFs increases linearly to 5.10 &#177; 0.20 &#181;m within 15 min of the reaction. Therefore, the employed synthesis procedure is a simple and rapid approach for preparing Au DNFs/TiN/Si composites.

This study presents a feasible procedure for synthesizing gold dendritic nanoforests on titanium nitride/silicon substrates. The thickness of gold dendritic nanoforests increases linearly within 15 min of a synthesis reaction.

In this study, a high-power impulse magnetron sputtering system is used to coat a flat and firm titanium nitride (TiN) film on silicon (Si) wafers, and a ...

In Situ Synthesis of Gold Nanoparticles without Aggregation in the Interlayer Space of Layered Titanate Transparent Films

Summary

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