The Grafting of Hydroxyaromatic Organics within Layered Perovskites via a Microwave-Assisted Method.

A new series of inorganic-organic hybrid perovskite materials were prepared by microwave-assisted grafting reactions. Simple carboxylic acids, acetic acid, and propionic acid, as well as hydroxyaromatic carboxylic acids, 3,5-dihydroxy benzoic acid (DBA), 5-hydroxyisophthalic acid (HPA), 4-hydroxybenzoic acid (HBA), and 4-hydroxy-4-biphenyl carboxylic acid (HBCA), were reacted with the Dion-Jacobson double-layered perovskite, HLaNbO and its alcoxy derivatives. Grafting was found to not occur with simple carboxylic acids, while those molecules with hydroxyls were all attached to the perovskite interlayers.

Correction: Blanco et al. Synthesis and Characterization of [Fe(Htrz)(trz)](BF)] Nanocubes. 2022, , 1213.

After publication of the paper [...

Platinum@Hexaniobate Nanopeapods: A Directed Photocatalytic Architecture for Dye-Sensitized Semiconductor H Production under Visible Light Irradiation.

Platinum@hexaniobate nanopeapods (Pt@HNB NPPs) are a nanocomposite photocatalyst that was selectively engineered to increase the efficiency of hydrogen production from visible light photolysis. Pt@HNB NPPs consist of linear arrays of high surface area Pt nanocubes encapsulated within scrolled sheets of the semiconductor H K NbO and were synthesized in high yield a facile one-pot microwave heating method that is fast, reproducible, and more easily scalable than multi-step approaches required by many other state-of-the-art catalysts. The Pt@HNB NPPs' unique 3D architecture enables physical separation of the Pt catalysts from competing surface reactions, promoting electron efficient delivery to the isolated reduction environment along directed charge transport pathways that kinetically prohibit recombination reactions.

Rapid Synthesis of Kaolinite Nanoscrolls through Microwave Processing.

Kaolinite nanoscrolls (NScs) are halloysite-like nanotubular structures of great interest due to their ability to superimpose halloysite's properties and applicability. Especially attractive is the ability of these NScs to serve as reaction vessels for the uptake and conversion of different chemical species. The synthesis of kaolinite NScs, however, is demanding due to the various processing steps that lead to extended reaction times.

Synthesis and Characterization of [Fe(Htrz)(trz)](BF)] Nanocubes.

Compounds that exhibit spin-crossover (SCO) type behavior have been extensively investigated due to their ability to act as molecular switches. Depending on the coordinating ligand, in this case -1,2,4-triazole, and the crystallite size of the SCO compound produced, the energy requirement for the spin state transition can vary. Here, SCO [Fe(Htrz)(trz)](BF)] nanoparticles were synthesized using modified reverse micelle methods.

Microwave Synthetic Routes for Shape-Controlled Catalyst Nanoparticles and Nanocomposites.

The use of microwave irradiation for the synthesis of inorganic nanomaterials has recently become a widespread area of research that continues to expand in scope and specialization. The growing demand for nanoscale materials with composition and morphology tailored to specific applications requires the development of facile, repeatable, and scalable synthetic routes that offer a high degree of control over the reaction environment. Microwave irradiation provides unique advantages for developing such routes through its direct interaction with active reaction species, which promotes homogeneous heat distribution, increased reaction rates, greater product quality and yield, and use of mild reaction conditions.

Room-Temperature Aqueous Suzuki-Miyaura Cross-Coupling Reactions Catalyzed via a Recyclable Palladium@Halloysite Nanocomposite.

A reliable method for encapsulation of palladium nanoparticles (6-8 nm particles) in halloysite (Pd@Hal) has been developed. The Pd@Hal was found to be a highly efficient room-temperature catalyst for Suzuki-Miyaura cross-coupling reactions that gave high yields of a diverse array of coupling products in 5:2 n-PrOH/HO within 1 h. The catalytic system was remarkably effective with a broad substrate scope.

Rapid and Controlled In Situ Growth of Noble Metal Nanostructures within Halloysite Clay Nanotubes.

A rapid (≤2 min) and high-yield low-temperature synthesis has been developed for the in situ growth of gold nanoparticles (NPs) with controlled sizes in the interior of halloysite nanotubes (HNTs). A combination of HAuCl in ethanol/toluene, oleic acid, and oleylamine surfactants and ascorbic acid reducing agent with mild heating (55 °C) readily lead to the growth of targeted nanostructures. The sizes of Au NPs are tuned mainly by adjusting nucleation and growth rates.

From Tetrahedral to Octahedral Iron Coordination: Layer Compression in Topochemically Prepared FeLaTiO.

Synthesis, characterization, and thermal modification of the new layered perovskite FeLaTiO have been studied. FeLaTiO was prepared by ion exchange of the triple-layered Ruddlesden-Popper phase LiLaTiO with FeCl at 350 °C under static vacuum. Rietveld refinement on synchrotron X-ray diffraction data indicates that the new phase is isostructural with CoLaTiO, where Fe cations occupy slightly compressed/flattened interlayer tetrahedral sites.

Rapid Topochemical Modification of Layered Perovskites via Microwave Reactions.

An effective microwave approach to the topochemical modification of different layered oxide perovskite hosts is presented where cation exchange, grafting, and intercalation reactions with acid, n-alkyl alcohols, and n-alkylamines, respectively, are successfully carried out. Microwave-assisted proton exchange reactions involving double- and triple-layered Dion-Jacobson and Ruddlesden-Popper perovskite family members, RbLnNb2O7 (Ln = La, Pr), KCa2Nb3O10, Li2CaTa2O7, and Na2La2Ti3O10, were found to be quite efficient, decreasing reaction times from several days to ≤3 h. Grafting and intercalation reactions involving double-layered perovskites were also quite rapid with full conversions occurring in as fast as an hour.

Controlling Pore Geometries and Interpore Distances of Anodic Aluminum Oxide Templates via Three-Step Anodization.

Porous alumina membranes have attracted much attention because they are very useful templates for the fabrication of various nanostructures important to nanotechnology. However, there are challenges in controlling pore geometries and interpore distances in alumina templates while maintaining highly ordered hexagonal pore structures. Herein, a three-step anodization method is utilized to prepare anodic alumina templates with various pore morphologies (e.

Synthesis and characterization of the rare-earth Dion-Jacobson layered perovskites, APrNb2O7 (A = Rb, Cs and CuCl).

The new double-layered perovskites, APrNb(2)O(7) (A = Rb, Cs) have been prepared by a high temperature ceramic method. Rietveld refinement of X-ray powder diffraction data confirmed the orthorhombic and tetragonal structures, respectively; RbPrNb(2)O(7) was refined in space group Imma (a = 5.4534(7) Å, b = 22.

Particle placement and sheet topological control in the fabrication of Ag-hexaniobate nanocomposites.

Synthetic methods are demonstrated that allow for the fabrication of Ag-hexaniobate nanocomposites with directed nanoparticle (NP) placement and nanosheet morphological control. The solvothermal treatment of exfoliated nanosheets (NSs) in the presence of Ag NPs leads to a high yield of Ag nanocomposites. This approach is quite flexible and, with control of time and temperature, can be used to produce nanocomposites with specific architectures; Ag NPs can be attached to nanosheets, attached to the surfaces of nanoscrolls, or at higher temperatures, captured within nanoscrolls to form nanopeapod (NPP) structures.

Iron oxide nanotubes synthesized via template-based electrodeposition.

Considerable effort has been invested in the development of synthetic methods for the preparation iron oxide nanostructures for applications in nanotechnology. While a variety of structures have been reported, only a few studies have focused on iron oxide nanotubes. Here, we present details on the synthesis and characterization of iron oxide nanotubes along with a proposed mechanism for FeOOH tube formation.

Peapod-type nanocomposites through the in situ growth of gold nanoparticles within preformed hexaniobate nanoscrolls.

A facile in situ method to grow Au nanoparticles (NPs) in hexaniobate nanoscrolls is applied to the formation of plasmonic Au@hexaniobate and bifunctional plasmonic-magnetic Au-Fe3 O4 @hexaniobate nanopeapods (NPPs). Utilizing a solvothermal treatment, rigid multiwalled hexaniobate nanoscrolls and partially filled Fe3 O4 @hexaniobate NPPs were first fabricated. These nanostructures were then used as templates for the controlled in situ growth of Au NPs.

Topochemical synthesis of alkali-metal hydroxide layers within double- and triple-layered perovskites.

The formation of alkali-metal hydroxide layers within lamellar perovskites has been accomplished by a two-step topochemical reaction strategy. Reductive intercalation of ALaNb2O7 with alkali metal (A = K, Rb) and RbCa2Nb3O10 with Rb leads to A2LaNb2O7 and Rb2Ca2Nb3O10, respectively. Oxidative intercalation with stoichiometric amounts of water vapor, produced by the decomposition of calcium oxalate monohydrate in a sealed ampule, allows the insertion hydroxide species.

Fabrication of nanopeapods: scrolling of niobate nanosheets for magnetic nanoparticle chain encapsulation.

Scrolling of niobate nanosheets (NSs) in the presence of magnetic nanoparticle (NP) chains can lead to peapodlike structures. Surface functional groups on both the NSs and NPs are important in directing the assembly and subsequent NS convolution. The dimensions of the peapods are typically dictated by the diameters of the NPs and the length of the NP chains.

Topochemical manipulation of perovskites: low-temperature reaction strategies for directing structure and properties.

Topochemical reaction strategies offer an important low-temperature (<500 °C) approach to the conscious manipulation of various inorganic host materials, allowing access to compounds that cannot be prepared by standard high-temperature methods. As the utility of these strategies continues to expand, researchers will be able to more effectively target materials with technologically significant properties. This Progress Report presents recent advances in topochemical reaction strategies as applied to perovskite and perovskite-related compounds.

Precise voltage contrast image assisted positioning for in situ electron beam nanolithography for nanodevice fabrication with suspended nanowire structures.

In this paper, we demonstrate precise voltage contrast image positioning for in situ electron beam (e-beam) nanolithography to integrate nanowires into suspended structures for nanoswitch fabrication. The positioning of the deflection electrodes on the nanowires can be well controlled using a precise voltage contrast image positioning technique, where the error can be minimized to about 10 nm. Using such a method, dispersed nanowires can be sandwiched between two layers of resist and suspended by one e-beam nanolithography process without any etching.

Building alkali-metal-halide layers within a perovskite host by sequential intercalation: (A(2)Cl)LaNb(2)O(7) (A = Rb, Cs).

Alkali-metal-halide layers were constructed within Dion-Jacobson (DJ) layered perovskites by a two-step sequential intercalation method. Reductive intercalation with an alkali metal, followed by oxidative intercalation with chlorine gas, leads to the formation of the compounds, (A(2)Cl)LaNb(2)O(7) (A = Rb, Cs). Rietveld refinement of X-ray powder diffraction data shows that an alkali-metal-halide layer is formed between the perovskite blocks.

Patterned metal nanowire arrays from photolithographically-modified templates.

An effective procedure for the fabrication of patterned nanowire arrays with micron-sized features is presented. Photolithographic methods are utilized to form set patterns onto porous anodic alumina membranes (AAM), and these modified membranes can then be used in the electrochemical growth of nanowire arrays. This approach readily allows the formation of a variety of nanowire array patterns with line widths down to several microns.

Fabrication of colloidal crystals with tubular-like packings.

Methods are reported for the fabrication of colloidal crystal wires with tubular packings. Both free and silica-encased wires have been prepared. Porous silicon membranes are infiltrated with silica spheres, treated with silane, and annealed.

Synthesis of porous wires from directed assemblies of nanospheres.

A method is reported for the fabrication of wires with extended pore structures. Nanospheres are initially infiltrated into the one-dimensional channels of alumina or polymer porous membranes. Metal is then electrochemically deposited within the channels.

Formation of metal-anion arrays within layered perovskite hosts. Preparation of a series of new metastable transition-metal oxyhalides, (MCl)LaNb(2)O(7) (M = Cr, Mn, Fe, Co).

A new series of transition-metal oxyhalides (MCl)LaNb(2)O(7) (M = Cr, Mn, Fe, Co) have been prepared by a simple topochemical route. Layered perovskite hosts (ALaNb(2)O(7), A = Li, Na, K or Rb) were reacted with the corresponding anhydrous metal halides under mild reaction conditions (<400 degrees C). The compounds were examined by X-ray powder diffraction; the series appears to be isostructural with (CuCl)LaNb(2)O(7), and the layer spacings, with the exception of M = Co, follow the trend expected from transition-metal cationic radii.