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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, HLaNb 2 O 7, 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. Reactivity of the hydroxyaromatic carboxylic acids varied with the different layered perovskite hosts where reactions with HLaNb 2 O 7 did not occur, and those with n-propoxy-LaNb 2 O 7 were limited; the greatest extent of reactivity was seen with n-decoxy-LaNb 2 O 7 . This is attributed to the larger interlayer spacing available for the insertion of the various hydroxyaromatic carboxylic acid compounds. The loading exhibited by the grafting species was less than that seen with well-known long-chain alkoxy grafting groups. It is expected that the width of the molecules contributes to this where, due to the benzyl groups, the interlayer volume of the grafted moieties occupies a larger horizontal fraction, therefore minimizing the loading to the below half. X-ray powder diffraction and transmission electron microscopy studies found that grafting of the n-decoxy-LaNb 2 O 7 intermediates with the series of hydroxyaromatics resulted in a reduction in crystallinity along with a disruption of the layer structure. Raman data on the series show little variation in local structure except for HBCA, where there appears to be a lengthening of the Nb-O apical linkage and a possible reduction in the distortion of inner-layer NbO 6 octahedra. The optical properties of the hydroxyaromatic carboxylic acid grafted perovskites were also investigated using diffuse-reflectance UV-Vis spectroscopy. The band gaps of DBA, HPA, and HBA were found to be similar to the parent (E g ≈ 3.4 eV), while the HBCA was significantly less by ca. 0.6 eV. This difference is attributed to electron withdrawal from the perovskite block to the HBCA ligand, leading to a lower band gap for the HBCA compound. The methods described herein allow for the formation of a new series of inorganic-organic hybrid materials where the products are of interest as precursors to more complex architectures as well as models for band gap modification of metal oxide photocatalysts.

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 x K 4- x Nb 6 O 17 and were synthesized in high yield via 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. Pt@HNB NPPs' catalytic activity was assessed in direct comparison to representative state-of-the-art Pt/semiconductor nanocomposites (extPt-HNB NScs) and unsupported Pt nanocubes. Photolysis under similar conditions exhibited superior H 2 production by the Pt@HNB NPPs, which exceeded other catalyst H 2 yields (μmol) by a factor of 10. Turnover number and apparent quantum yield values showed similar dramatic increases over the other catalysts. Overall, the results clearly demonstrate that Pt@HNB NPPs represent a unique, intricate nanoarchitecture among state-of-the-art heterogeneous catalysts, offering obvious benefits as a new architectural pathway toward efficient, versatile, and scalable hydrogen energy production. Potential factors behind the Pt@HNB NPPs' superior performance are discussed below, as are the impacts of systematic variation of photolysis parameters and the use of a non-aqueous reductive quenching photosystem., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

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. Generally, three intercalation stages are involved in the synthesis, where the second step of methylation dominates others in terms of duration. The present research shows that introducing microwave processing throughout the various steps can simplify the procedure overall and reduce the synthesis period to less than a day (14 h). The kaolinite nanoscrolls were obtained using two final intercalating agents, aminopropyl trimethoxy silane (APTMS) and cetyltrimethylammonium chloride (CTAC). Both produce abundant NScs, as corroborated by microscopy measurements as well as the surface area of the final products; APTMS intercalated NScs were 63.34 m 2 /g, and CTAC intercalated NScs were 73.14 m 2 /g. The nanoscrolls averaged about 1 μm in length with outer diameters of APTMS and CTAC intercalated samples of 37.3 ± 8.8 nm and 24.9 ± 6.1 nm, respectively. The availability of methods for the rapid production of kaolinite nanoscrolls will lead to greater utility of these materials in technologically significant applications.

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 1H -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) 2 (trz)](BF 4 )] nanoparticles were synthesized using modified reverse micelle methods. Reaction conditions and reagent ratios are strictly controlled to produce nanocubes of 40-50 nm in size. Decreases in energy requirements are seen in both thermal and magnetic transitions for the smaller sized crystallites, where, compared to bulk materials, a decrease of as much as 20 °C can be seen in low to high spin state transitions.

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. Many catalytic nanomaterials such as noble metal nanoparticles and intricate nanocomposites have very limited synthetic routes due to their extreme temperature sensitivity and difficulty achieving homogeneous growth. This work presents recent advances in the use of MW irradiation methods to produce high-quality nanoscale composites with controlled size, morphology, and architecture.

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/H 2 O within 1 h. The catalytic system was remarkably effective with a broad substrate scope. In addition, the catalyst was easily recovered and recycled without a significant loss of catalytic activity.

Recent advances in exploiting microwave radiation in the topochemical modification of layered oxide perovskites are presented. Such methods work well for rapid bulk synthetic steps used in the production of novel inorganic-organic hybrids (protonation, grafting, intercalation, and in situ click reactions), exfoliation to produce dispersed nanosheets, and post-exfoliation processing to rapidly vary nanosheet surface groups. Compared to traditional methods that often take days, microwave methods can produce quality products in as little as 1-2 h.

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 4 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. Further modification of the process, through an increase in ascorbic acid, allows for the formation of nanorods (NRs)/nanowires within the HNTs. This approach is not limited to gold-a modified version of this synthetic strategy can also be applied to the formation of Ag NPs and NRs within the clay nanotubes. The ability to readily grow such core-shell nanosystems is important to their further development as nanoreactors and active catalysts. NPs within the tube interior can further be manipulated by the electron beam. Growth of Au and Ag could be achieved under a converged electron beam suggesting that both Au@HNT and Ag@HNT systems can be used for the fundamental studies of NP growth/attachment.

Synthesis, characterization, and thermal modification of the new layered perovskite FeLa 2 Ti 3 O 10 have been studied. FeLa 2 Ti 3 O 10 was prepared by ion exchange of the triple-layered Ruddlesden-Popper phase Li 2 La 2 Ti 3 O 10 with FeCl 2 at 350 °C under static vacuum. Rietveld refinement on synchrotron X-ray diffraction data indicates that the new phase is isostructural with CoLa 2 Ti 3 O 10 , where Fe II cations occupy slightly compressed/flattened interlayer tetrahedral sites. Magnetic measurements on FeLa 2 Ti 3 O 10 display Curie-Weiss behavior at high temperatures and a spin-glass transition at lower temperatures (<30 K). Thermal treatment in oxygen shows that FeLa 2 Ti 3 O 10 undergoes a significant cell contraction (Δc ≈ -2.7 Å) with a change in the oxidation state of iron (Fe 2+ to Fe 3+ ); structural analysis and Mössbauer studies indicate that upon oxidation the local iron environment goes from tetrahedral to octahedral coordination with some deintercalation of iron as Fe 2 O 3 to produce Fe 0.67 La 2 Ti 3 O 10 .

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. Interestingly, triple-layered hosts were found to show different behavior; when complete intercalations were possible, grafting reactions were limited at best. Utilization of this rapid synthetic approach could help facilitate the fabrication of new organic-inorganic hybrids.

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 = 22.012(1) Å, c = 5.4549(7) Å) and CsPrNb(2)O(7) in P4/mmm (a = 3.8668(2) Å, c = 11.163(1) Å). (CuCl)PrNb(2)O(7), topochemically prepared by replacement of Rb(+)/Cs(+) with CuCl(+), contains a 2D Cu-Cl network between the PrNb(2)O(7) slabs (orthorhombic space group Pbam, a = 7.7328(6) Å, b = 7.7113(4) Å and c = 11.6706(3) Å). The parent compounds both show paramagnetic behavior μ(eff) (Rb) = 3.34(1)μ(B) and μ(eff) (Cs) = 3.60(2)μ(B) while the (CuCl)PrNb(2)O(7), paramagnetic (μ(eff) = 4.020(8)μ(B)) down to 20 K, exhibits antiferromagnet-like behavior below 20 K.

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. The decorated nanosheets and nanoscrolls show surface plasmon resonance (SPR) maxima similar to that of free Ag NPs, while the Ag NPPs exhibit a red shift of about 10 nm.

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.g., arched-shape, tree-like, branched-shape) and tunable interpore distances. Such structures are not found within the more traditional alumina templates fabricated by a two-step anodization of aluminum films. The range of interpore distances and pore diameters within the modified templates increases with increasing voltages. In contrast, under decreasing voltages, hexagonally ordered pores can also branch into several pores with smaller sizes and reduced interpore distances. Electrochemical growth of metal nanowires in the modified templates helps to highlight details of the pore structures and which pore channels are active.

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. The FeOOH nanotubes, fabricated via a template-based electrodeposition method, are found to exhibit a unique inner-surface. Heat treatment of these tubes under oxidizing or reducing atmospheres can produce either hematite (α-Fe2O3) or magnetite (Fe3O4) structures, respectively. Hematite nanotubes are composed of small nanoparticles less than 20 nm in diameter and the magnetization curves and FC-ZFC curves show superparamagnetic properties without the Morin transition. In the case of magnetite nanotubes, which consist of slightly larger nanoparticles, magnetization curves show ferromagnetism with weak coercivity at room temperature, while FC-ZFC curves exhibit the Verwey transition at 125 K.

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. The resulting peapod structures exhibited high filling fractions and long-range uniformity. Optical measurements showed a progressive red shift in plasmonic behavior between Au NPs, Au NPPs, and Au-Fe3 O4 NPPs; magnetic studies found that the addition of gold in the Fe3 O4 @hexaniobate NPPs reduced interparticle coupling effects. The development of this approach allows for the routine bulk preparation of noble-metal-containing bifunctional nanopeapod materials., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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. Compounds of the form (A2OH)LaNb2O7 (A = K, Rb) and (Rb2OH)Ca2Nb3O10 are accessible. X-ray diffraction data indicates a clear layer expansion of almost 3 Å on the insertion of hydroxide relative to that of the parent. Rietveld refinement of neutron diffraction data collected on deuterated samples of (Rb2OD)LaNb2O7 (P4/mmm space group, a = 3.9348(1) Å, c = 14.7950(7) Å) finds that both rubidium and oxygen species reside in cubic sites forming a CsCl-like interlayer structure between niobate perovskite blocks. Hydrogens, attached to the interlayer oxygens, are disordered over a 4-fold site in the x-y plane and have O-H bond distances (0.98 Å) consistent with known hydroxide species. This synthetic approach expands the library of available topochemical reactions, providing a facile method for the construction of alkali-metal hydroxide layers within receptive perovskite hosts.

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 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. Emphasis is placed on structural modifications and corresponding variations in properties. Additionally, the future prospects of this approach to the rational design of intricate target compounds are discussed., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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. The in situ e-beam nanolithography eliminates the stage movement error by preventing any movements of the stage during the nanolithography process; hence, a high precision laser stage and alignment marks on the substrate are not needed, which simplifies the traditional e-beam nanolithography process. The nanoswitches fabricated using this method show ON and OFF states with the changes of applied voltages. This simplified process provides an easy, low cost and less time-consuming route to integrating suspended nanowire based structures using a converted field emission scanning electron microscope e-beam system, which can also be customized to fabricate multi-layer structures and a site-specific nanodevice fabrication.

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. The alkali-metal cation is eight-coordinate with four oxygens from the perovskite layer and four chlorides from the new halide layer; this environment is similar to cesium in the CsCl structure (B2). Thermal analysis indicates that these are low-temperature phases where decomposition begins by 400 degrees C. Details on the synthesis and characterization of this set of compounds are presented, and the general utility of this approach discussed.

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.

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. After removal of the silicon template, short annealing times were found to result in colloidal crystal wires with varied packing geometries, while repeated annealing cycles produced a thin translucent silica sheath around the wires. Packing in the wires varies with the channel diameter of the Si membrane. The channels used in this study typically produce colloidal crystal wires with six strands, though wires with four to seven strands have been observed. Both chiral and achiral packings are also possible.

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. Removal of the membrane and nanospheres results in porous wires. The production of 1-mum diameter wires with 300- or 500-nm diameter pores and 300-nm diameter wires with 140-nm pores illustrates the utility of this approach. Contacts between the spheres and the channel wall result in openings on the surface of the wires, and contacts between the spheres themselves produce openings between adjacent pores. Some short-range ordering of the spheres within the channels, as reflected in the wire pore structure, is evident. Characterization of the porous wires by electron microscopy is presented, and the potential applications of materials is discussed.

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. Thermal analysis with differential scanning calorimetry (DSC) shows the materials to be metastable where all four compounds decompose exothermically above 690 degrees C.

The construction of two-dimensional (2D) copper halide networks within a variety of perovskite hosts by a low-temperature topochemical method is demonstrated. Ion exchange between some layered perovskite oxides of the type A'[An - 1(M,M')nO3n + 1] (A' = alkali metal, H, NH4; A = alkaline earth, rare earth, or Bi; M,M' = Nb, Ta, Ti; n = 2, 3) with CuX2 (X = Cl, Br) results in the oxyhalides (CuX)[An - 1(M,M')nO3n + 1]. Rietveld refinements from X-ray powder diffraction data show that the structures of these new copper oxyhalides contain edge-sharing CuO2X4 octahedra sandwiched between the M/M'O6 octahedra of the perovskite slabs. The compounds are low-temperature phases that decompose well below 700 degrees C. The copper oxyhalides exhibit antiferromagnetic ordering resulting from the magnetic exchange interactions within the planar Cu-X networks.

Precursor reactions based on metathetical (exchange) pathways have been found to be an effective synthetic route for the preparation of a large number of materials. These solid-solid reactions are extremely rapid (typically less than 1 second) and often can be initiated at or near room temperature. They are potentially useful for controlling product particle size and for preparing highquality cationic or anionic solid solutions. The frequently self-propagating and sometimes explosive behavior exhibited by these reactions can be attributed to the large amount of heat they release. As a consequence, thermodynamic considerations can be used to help select the best set of precursors as judged from reaction enthalpies. The factors that influence these reactions are illustrated by a discussion of MoS(2), ZrN, MoSi(2), and GaAs, examples of the many compounds accessible by this synthetic route.

A major barrier to use of new measurement methodologies in behavioral research has been the difficulties encountered in collecting individual judgements. Balanced incomplete block design (BIBD) procedures offer enormous flexibility in the way judgmental data may be collected. The advantages and disadvantages of BIBDs are clarified and their use is demonstrated with an empirical example. A procedure for reducing data of this type to analyzable form is proposed and an analytical approach that is appropriate for the resulting data is illustrated.