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Nanoparticles of nickel phosphide (Ni2P) have been investigated for electrocatalytic activity and stability for the hydrogen evolution reaction (HER) in acidic solutions, under which proton exchange membrane-based electrolysis is operational. The catalytically active Ni2P nanoparticles were hollow and faceted to expose a high density of the Ni2P(001) surface, which has previously been predicted based on theory to be an active HER catalyst. The Ni2P nanoparticles had among the highest HER activity of any non-noble metal electrocatalyst reported to date, producing H2(g) with nearly quantitative faradaic yield, while also affording stability in aqueous acidic media.

The M1 form of vanadium dioxide, which exhibits a reversible insulator-metal transition above room temperature, has been incorporated into nanoscale heterostructures through solution-phase epitaxial growth on the tips of rutile TiO2 nanorods. Four distinct classes of VO2-TiO2-VO2 nanorod heterostructures are accessible by modulating the growth conditions. Each type of VO2-TiO2-VO2 nanostructure has a different insulator-metal transition temperature that depends on the VO2 domain sizes and the TiO2-VO2 interfacial strain characteristics. [ABSTRACT FROM AUTHOR]

Molybdenum ditelluride, MoTe2, is emerging as an important transition-metal dichalcogenide (TMD) material because of its favorable properties relative to other TMDs. The 1T ′ polymorph of MoTe2 is particularly interesting because it is semimetallic with bands that overlap near the Fermi level, but semiconducting 2H-MoTe2 is more stable and therefore more accessible synthetically. Metastable 1T ′-MoTe2 forms directly in solution at 300 °C as uniform colloidal nanostructures that consist of few-layer nanosheets, which appear to exhibit an approx. 1 % lateral lattice compression relative to the bulk analogue. Density functional theory calculations suggest that small grain sizes and polycrystallinity stabilize the 1T ′ phase in the MoTe2 nanostructures and suppress its transformation back to the more stable 2H polymorph through grain boundary pinning. Raman spectra of the 1T ′-MoTe2 nanostructures exhibit a laser energy dependence, which could be caused by electronic transitions. [ABSTRACT FROM AUTHOR]

New synthetic innovations are rapidly being developed to address the demand for complex, next-generation nanomaterials with rigorously controlled architectures and interfaces. This Review highlights key strategies for the chemical transformation and stepwise synthesis of multicomponent inorganic nanostructures, with the existing nanoscale transformations categorized into classes of reactions that are related to those used in the synthesis of organic molecules. The application of concepts used in molecular synthesis-including site-selectivity, regio- and chemoselectivity, orthogonal reactivity, coupling reactions, protection/deprotection strategies, and procedures for separation and purification-to nanoscale systems is emphasized. Collectively, the resulting synthetic concept represents an emerging model for the synthesis of complex inorganic nanostructures on the basis of the guiding principles that underpin the multistep total synthesis of complex organic molecules and natural products. [ABSTRACT FROM AUTHOR]

Nanostructures of layered transition metal dichalcogenide (TMD) alloys with tunable compositions are promising candidates for a broad scope of applications in electronics, optoelectronics, topological devices, and catalysis. Most TMD alloy nanostructures are synthesized as films on substrates using gas-phase methods at high temperatures. However, lower temperature solution routes present an attractive alternative with the potential for larger-scale, higher-yield syntheses of freestanding, higher surface area materials. Here, we report the direct solution synthesis of colloidal few-layer TMD alloys, MoxW1-xSe2 and WS2ySe2(1-y), exhibiting fully tunable metal and chalcogen compositions that span the MoSe2- WSe2 and WS2-WSe2 solid solutions, respectively. Chemical guidelines for achieving the targeted compounds are presented, along with comprehensive structural characterizations (X-ray diffraction, electron microscopy, Raman, and UV-visible spectroscopies). High-resolution microscopic imaging confirms the formation of TMD alloys and identifies a random distribution of the alloyed elements. Analysis of the tilt-angle dependency of the intensities associated with atomic-resolution annular dark field imaging line scans reveals the types of point vacancies present in the samples, thus providing atomic-level insights into the structures of colloidal TMD alloy nanostructures that were previously only accessible for substrate-confined films. The A excitonic transition of the TMD alloy nanostructures can be readily adjusted between 1.51 and 1.93 eV through metal and chalcogen alloying, correlating the compositional modulation to the realization of tunable optical properties. [ABSTRACT FROM AUTHOR]

The article presents information on a study which describes a new strategy for synthesizing nanostructures of transition metal phosphides. The strategy involves a different mechanism, that is, the conversion of preformed metal nanoparticles into metal phosphides by solution-mediated reaction with trioctylphosphine (TOP). It has been found that a variety of transition metal phosphide nanocrystals can be accessed by the solution-mediated reaction of preformed metal nanoparticles with TOP.

This article focuses on a study related to one-pot synthesis of hollow superparamagnetic CoPt nanospheres. Hollow nanospheres have emerged as intriguing materials for diverse applications that include drug delivery, bioencapsulation, medical diagnostics, catalysis, plasmonics, and composite electronic and structural materials. Despite recent advances in synthesizing metal nanostructures with controlled morphologies, there are very few reports of bimetallic hollow nanospheres. Bimetallic systems often offer advantages over single-metal systems.

Iron–germanium(Fe–Ge) is a complex alloy systemthat includes several structurally and compositionally diverse phasesthat exhibit a range of interesting magnetic properties that can changesignificantly when reduced to nanoscale dimensions. Fe–Ge nanostructureshave been synthesized using chemical and physical deposition methodsbut have not previously been accessible as solution-synthesized colloidalmaterials. Here, we show that colloidal Fe–Ge nanostructurescan be synthesized via the hot injection of an oleylamine solutionof Fe(CO)5into a solution containing GeI4,oleylamine, oleic acid, and hexamethyldisilazane. This approach effectivelymerges recent advances in the synthesis of colloidal Ge nanocrystalswith methods routinely used to synthesize metal and alloy nanoparticles.At 260 °C, spherical nanocrystals of Ni2In-type Fe3Ge2form. Heating the solution at 300 °C transformsthe spherical Fe3Ge2nanocrystals into CoGe-typeFeGe nanowires. The Fe3Ge2nanocrystals areferromagnetic with Tc≈ 265 K,whereas the FeGe nanowires are only weakly magnetic. [ABSTRACT FROM AUTHOR]

Abstract: Mackinawite, a metastable 1:1 compound of iron and sulfur that adopts an anti-PbO-type structure, is of interest because of its relationship to known iron chalcogenide superconductors, as well as its biogeochemical relevance. Colloidal nanosheets of mackinawite-type FeS were synthesized by first generating an amorphous Fe–S precursor via the aqueous room-temperature co-precipitation of Fe2+ and S2−, then solvothermally crystallizing it in ethylene glycol at 200°C in an autoclave. The product is highly crystalline, with lattice constants of a=3.674(3)Å and c=5.0354(3)Å. The nanosheets, with their surface normal oriented along the [001] direction, are irregularly faceted with edge lengths that range from 100nm to over 1μm and average thicknesses of approx. 30nm. The samples showed a ferromagnetic background signal with no evidence of superconductivity. [Copyright &y& Elsevier]

Narrow-band-gap IV-VI semiconductors offer promising optoelectronic properties for integration as light-absorbing components in field-effect transistors, photodetectors, and photovoltaic devices. Importantly, colloidal nanostructures of these materials have the potential to substantially decrease the fabrication cost of solar cells because of their ability to be solution-processed. While colloidal nanomaterials formed from IV-VI lead phalcogenides such as PbS and PbSe have been extensively investigated, those of the layered semiconductors SnS, SnSe, GeS, and GeSe have only recently been considered. In particular, there have been very few studies of the germanium chalcogenides, which have band-gap energies that overlap well with the solar spectrum. Here we report the first synthesis of colloidal GeS and GeSe nanostructures obtained by heating Gel4, hexamethyldisilazane, oleylamine, oleic acid, and dodecanethiol or trioctylphosphine selenide to 320 °C for 24 h. These materials, which were characterized by TEM, SAED, SEM, AFM, XRD, diffuse reflectance spectroscopy, and I-V conductivity measurements, preferentially adopt a two-dimensional single-crystal panosheet morphology that produces fully [100]-oriented films upon drop-casting. Optical measurements indicated indirect band gaps of 1.58 and 1.14 eV for GeS and GeSe, respectively, and electrical measurements showed that drop-cast films of GeSe exhibit p-type conductivity. [ABSTRACT FROM AUTHOR]

The article focuses on the synthesis of uniform ultrathin CuPt nanorods. The methods involve in the synthesis of CuPt nanoparticle goes through coprecipitation and impregnation, reverse micelles and polyol reduction. In the article, the facile synthetic approach is described in the one dimensional (ID) nanostructures with its corresponding catalytic activity.

The article presents a study which examines the conversion of metal nanoparticles into multimetal nanoparticle products through solution chemistry reactions. It discusses the process of transformation of metal nanoparticles structures into multielement shape-controlled nanostructures. It concludes that the solution chemistry conversion reactions that were developed for metal nanoparticles are directly applicable to on-wire transformations.