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X-ray-based analytics are routinely applied in many fields, including physics, chemistry, materials science, and engineering. The full potential of such techniques in the life sciences and medicine, however, has not yet been fully exploited. We highlight current and upcoming advances in this direction. We describe different X-ray-based methodologies (including those performed at synchrotron light sources and X-ray free-electron lasers) and their potentials for application to investigate the nano-bio interface. The discussion is predominantly guided by asking how such methods could better help to understand and to improve nanoparticle-based drug delivery, though the concepts also apply to nano-bio interactions in general. We discuss current limitations and how they might be overcome, particularly for future use in vivo .

The design and performance of a semi-preparative asymmetrical flow field-flow fractionation (SP-AF4) channel are investigated with the objective of better understanding and exploiting the relationship between channel dimensions, sample loading, and resolution. Most size-based separations of nanometer and submicrometer particles are currently limited to analytical scale quantities (<100μg). However, there is a strong need to fractionate and collect larger quantities so that fundamental properties of the more narrowly dispersed fractions can be studied using additional characterization methods and for subsequent applications. In this work, dimensions of the spacer that defines the form of SP-AF4 channels are varied and their performances are assessed with respect to sample focusing position and loading. Separations are performed in aqueous and organic carrier fluids. A critical evaluation of channel dimensions showed that increasing the channel breadth is a practical and effective route to maintaining separation resolution while increasing sample loads to milligram quantities. Good size resolution (∼1.0) is achieved for separations of 10mg of 50 and 100nm silica nanoparticles suspended in water and up to 0.6mg of ∼10 to 35nm inorganic hybrid nanoparticles suspended in tetrahydrofuran. This work represents important advances in the understanding of SP-AF4 separations and extends sample loading capacities in both aqueous and organic solvents., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The design and use of materials in the nanoscale size range for addressing medical and health-related issues continues to receive increasing interest. Research in nanomedicine spans a multitude of areas, including drug delivery, vaccine development, antibacterial, diagnosis and imaging tools, wearable devices, implants, high-throughput screening platforms, etc. using biological, nonbiological, biomimetic, or hybrid materials. Many of these developments are starting to be translated into viable clinical products. Here, we provide an overview of recent developments in nanomedicine and highlight the current challenges and upcoming opportunities for the field and translation to the clinic.

Alloying metals can achieve enhanced kinetics for the hydrogen evolution reaction (HER), but most known HER alloy catalysts combine metals that are miscible in the bulk. Theoretical studies suggest that bulk‐immiscible AgRh alloys will exhibit near‐zero hydrogen binding energies, which is important for high‐performing HER catalysts. Current routes to AgRh nanoparticles yield only small quantities or require specialized setups. Here, we establish a ligand‐free, scalable synthesis of AgRh nanoparticles and demonstrate their catalytic viability for the HER under acidic conditions. AgRh nanoparticle electrodes exhibited low operating potentials with current densities of −10 and −100 mA/cm2 at overpotentials of −17 and −32 mV, respectively. The electrodes were highly durable with very little change in overpotentials required to maintain hydrogen production for 24 h and after 400 successive cycles. These results establish bulk‐immiscible AgRh alloys as promising non‐Pt HER catalysts. [ABSTRACT FROM AUTHOR]

Nanoscale transition metal tellurides are important materials for a variety of applications. However, solution‐phase methods to synthesize nanoscale transition metal tellurides are not as well‐developed as for related sulfide and selenide systems. Here, we show that pre‐formed colloidal metal nanoparticles react with bis(trimethylsilyl)telluride to form their corresponding tellurides. Nanoparticles of Pd, Pt, and Ni convert to nanoscale particles of the layered transition metal dichalcogenides PdTe2, PtTe2, and NiTe2 upon reaction with bis(trimethylsilyl)telluride. When Pd nanoparticles instead react with a TOP‐Te complex (TOP = trioctylphosphine), PdTe forms. This result demonstrates that the metal telluride phase that forms can be controlled by the reactivity of the tellurium reagent. Other nanoparticles, including Co, Ag, and Rh, also form crystalline metal tellurides upon reaction with bis(trimethylsilyl)telluride, which indicates that this approach to synthesizing nanoscale transition metal tellurides is general. [ABSTRACT FROM AUTHOR]

Conspectus Colloidal hybrid nanoparticles are solution-dispersible constructs that join together multiple distinct nanoscale materials through direct solid-solid interfaces. Given their multifunctionality and synergistic properties that emerge from interfacial coupling, hybrid nanoparticles are of interest for applications in biomedical imaging, solar energy conversion, heterogeneous catalysis, nanophotonics, and beyond. High-order hybrid nanoparticles, which incorporate three or more nanocrystal domains, offer greater tunability and functional diversity relative to one or two-component nanoparticles. The multiple heterojunctions within these structures can facilitate complex electromagnetic coupling as well as cooperative surface processes. Additionally, these materials can be used as model systems for studying fundamental structure-property relationships at the nanoscale that arise from particle coupling and interfacial exchanges. Limiting these advances is the inability to synthesize hybrid nanoparticles with precise morphologies and geometries. High-order hybrid nanoparticles can adopt more than one configuration, and each unique arrangement will have different heterointerfaces and, accordingly, different functions. Seeded-growth methods are among the most effective methods for producing high-quality hybrid nanoparticles. Engineering complex heterostructures using these stepwise reactions is in some ways conceptually analogous to the total synthesis of large organic molecules. However, unlike in molecular synthesis, the rules and guidelines that underpin the formation of hybrid nanoparticles are less understood. For example, when a third domain is added to a two-component heterodimer nanoparticle seed, several distinct types of hybrid nanoparticle products are possible, but only one is typically observed due to preferred growth at specific locations. The three-component heterotrimer products that preferentially form are not necessarily those that have the domain configurations and heterojunctions required to facilitate a targeted application. Different arrangements of the three nanoparticles that comprise a heterotrimer lead to distinct configurational isomers. Accordingly, understanding and controlling configurational isomerism in nanoparticle heterotrimers is foundational for engineering high-order hybrid nanostructures with targeted heterointerfaces, properties, and functionalities. This Account highlights recent insights into the pathways by which three-component nanoparticle heterotrimers form and how their configurations can be controlled and modified. In-depth microscopic investigations into the formation of heterotrimers by growing a third nanoparticle domain on a two-component heterodimer seed have revealed that in some cases indiscriminate nucleation first occurs on all exposed surfaces followed by surface-mediated migration and coalescence to the preferred interface. This insight helps to rationalize observed site-specific, chemoselective growth phenomena. Additionally, new approaches for directing growth in heterotrimer synthesis, such as protection-deprotection schemes inspired by organic chemistry, are becoming effective tools for constructing hybrid nanoparticles having nonpreferred domain configurations. Alternatives to traditional seeded-growth approaches are also emerging, including insertion reactions driven by saturation-precipitation processes and orthogonal transformations of preformed hybrid constructs using ion exchange. These and other recent advances are providing a powerful suite of synthetic tools that are anticipated to enable function-driven design of high-order hybrid nanoparticles having targeted properties and applications. [ABSTRACT FROM AUTHOR]

The ability to selectively form one crystal structure among several options in a polymorphic system is an important goal in solid-state synthesis. Nanocrystal cation exchange, which proceeds rapidly under mild conditions, can retain key structural features and yield otherwise inaccessible phases, but the extent to which crystal structure can be retained and therefore selectively targeted during such reactions has been limited. Here, we show that nanocrystals of digenite Cu2−xS transform to zincblende MnS and CoS upon cation exchange. Zincblende MnS and CoS, which are metastable in bulk, retain both the tetrahedral cation coordination and cubic close packed anion sublattice of digenite Cu2−xS. Comparison with wurtzite MnS and CoS, which have been accessed previously through analogous cation exchange of roxbyite Cu2−xS, demonstrates the selective formation of the related zincblende vs. wurtzite polymorphs by cation exchange of structurally distinct templates. [ABSTRACT FROM AUTHOR]

Nanoscale heterostructures that interface with multiple distinct materials provide opportunities to engineer functional complexity into single-particle constructs. However, existing synthetic pathways to such hybrid nanoparticles emphasize surface-seeded growth, which limits the scope of accessible systems. Here, we introduce an alternative approach that transforms isotropic nanocrystals into asymmetric, multicomponent Janus particles through sequential deposition, reactive phase segregation, and cation exchange processes that are mediated by an unusual class of reactive synthons. After Ag-Au seed particles had formed and had reacted with sulfur, a series of segregated Au1-xAgx-AgAuS and Au1-xAgx-Ag3AuS2 hybrid nanoparticles form. The AgAuS and Ag3AuS2 domains provide a synthetic entryway into solution-mediated cation exchange reactions, with the compositions of the Ag-Au-S synthons defining the components, morphologies, and interfaces of the hybrid nanoparticle products. Upon cation exchange with Pb2+, Au1-xAgx-AgAuS forms Ag1-xAux-PbS heterodimers while Au1-xAgx-Ag3AuS2 forms Ag1-xAux-Ag2S-PbS heterotrimers. The process by which isotropic metal nanoparticles transform into asymmetric hybrid nanoparticles through reactive Ag-Au-S synthons provides important insights that will be applicable to the retrosynthetic design of complex nanoscale heterostructures having expanded multifunctionality and synergistic properties. [ABSTRACT FROM AUTHOR]

Ion exchange reactions of colloidal nanocrystals provide access to complex products that are synthetically challenging using traditional hot-injection methods. However, such reactions typically achieve only partial material transformations by employing either cation or anion exchange processes. It is now shown that anion and cation exchange reactions can be coupled together and applied sequentially in one integrated pathway that leads to complete material transformations of nanocrystal templates. Although the product nanocrystals do not contain any of the original constituent elements, the original morphology is retained, thereby fully decoupling morphology and composition control. The sequential anion/cation exchange process was applied to pseudo-spherical CdO nanocrystals and ZnO tetrapods, producing fully transformed and shape-controlled nanocrystals of copper and silver sulfides and selenides. Furthermore, hollow core-shell tetrapod ZnS@CdS heterostructures were readily accessible. [ABSTRACT FROM AUTHOR]

Nanoparticles of cobalt phosphide, CoP, have been prepared and evaluated as electrocatalysts for the hydrogen evolution reaction (HER) under strongly acidic conditions (0.50 M H2SO4, pH 0.3). Uniform, multi-faceted CoP nanoparticles were synthesized by reacting Co nanoparticles with trioctylphosphine. Electrodes comprised of CoP nanoparticles on a Ti support (2 mg cm−2 mass loading) produced a cathodic current density of 20 mA cm−2 at an overpotential of −85 mV. The CoP/Ti electrodes were stable over 24 h of sustained hydrogen production in 0.50 M H2SO4. The activity was essentially unchanged after 400 cyclic voltammetric sweeps, suggesting long-term viability under operating conditions. CoP is therefore amongst the most active, acid-stable, earth-abundant HER electrocatalysts reported to date. [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]

Colloidal hybrid nanoparticles contain multiple nanoscale domains fused together by solid-state interfaces. They represent an emerging class of multifunctional lab-on-a-particle architectures that underpin future advances in solar energy conversion, fuel-cell catalysis, medical imaging and therapy, and electronics. The complexity of these 'artificial molecules' is limited ultimately by the lack of a mechanism-driven design framework. Here, we show that known chemical reactions can be applied in a predictable and stepwise manner to build complex hybrid nanoparticle architectures that include M-Pt-Fe3O4 (M = Au, Ag, Ni, Pd) heterotrimers, MxS-Au-Pt-Fe3O4 (M = Pb, Cu) heterotetramers and higher-order oligomers based on the heterotrimeric Au-Pt-Fe3O4 building block. This synthetic framework conceptually mimics the total-synthesis approach used by chemists to construct complex organic molecules. The reaction toolkit applies solid-state nanoparticle analogues of chemoselective reactions, regiospecificity, coupling reactions and molecular substituent effects to the construction of exceptionally complex hybrid nanoparticle oligomers. [ABSTRACT FROM AUTHOR]

Controlling the composition and phase formation of bulk and nanoscale solids underpins efforts to control physical properties. Here, we introduce a powerful new chemical pathway that facilitates composition-tunable synthesis, post-synthesis purification, and precise phase targeting in metal chalcogenide systems. `When metal sele-nides and sulfides react with trioctylphosphine (TOP) at temperatures that range from 65 to 270 °C, selenium and sulfur are selectively extracted to produce the most metal-rich chalcogenide that is stable in a particular binary system. This general approach is demonstrated for SnSe2, FeS2, NiSe2, and CoSe2, which convert to SnSe, FeS, Ni3Se2, and Co9Se8, respectively. In-depth studies of the Fe-Se system highlight the precise phase targeting and purification that is achievable, with PbO-type FeSe (the most metal-rich stable Fe-Se phase) forming exclusively when other Fe-Se phases, including mixtures, react with TOP. This chemistry also represents a new template-based nanoparticle "conversion chemistry" reaction, transforming hollow NiSe2 nano-spheres into hollow NiSe nanospheres with morphological retention. [ABSTRACT FROM AUTHOR]

Understanding how solids form is a challenging task, and few strategies allow for the elucidation of reaction pathways that are useful for designing new solids. Here, we describe an unusual multistep reaction pathway that leads to the formation of AuCuSn2, a new ternary intermetallic compound that was discovered as nanocrystals using a low-temperature solution route. The formation of AuCuSn2 using a modified polyol process occurs through a multistep pathway that was elucidated by taking aliquots throughout the course of the reaction and studying the products using a variety of techniques. The reaction proceeds through four distinct steps: (a) formation of Au nanoparticles at or near room temperature, mediated by a galvanic reaction between Au3+ and Sn2+ (forming Au0 and Sn4+, precipitated as SnO2 that forms a shell around the nanoparticles), (b) formation of NiAs-type AuSn nanoparticles, along with Cu and Sn, upon addition of NaBH4, (c) aggregation and thermal interdiffusion to form AuCuxSny alloy nanoparticles, and (d) nucleation of intermetallic AuCuSn2, which has an ordered NiAs-derived structure. The proposed mechanism was tested by starting the reaction with the AuSn intermediate. AuSn nanoparticles were synthesized separately and reacted with Cu and Sn nanoparticles, and ordered AuCuSn2 formed as expected. Elucidation of this reaction pathway has important implications for guiding the design of new intermetallic solids, as well as for controlling the synthesis of complex multimetal nanocrystals. [ABSTRACT FROM AUTHOR]

Intermetallic compounds and alloys are traditionally synthesized by heating mixtures of metal powders to high temperatures for long periods of time. A low-temperature solution-based alternative has been developed, and this strategy exploits the enhanced reactivity of nanoparticles and the nanometer diffusion distances afforded by binary nanocomposite precursors. Prereduced metal nanoparticles are combined in known ratios, and they form nanomodulated composites that rapidly transform into intermetallics and alloys upon heating at low temperatures. The approach is general in terms of accessible compositions, structures, and morphologies. Multiple compounds in the same binary system can be readily accessed; e.g., AuCu, AuCu3, Au3Cu, and the AuCu-II superlattice are all accessible in the Au-Cu system. This concept can be extended to other binary systems, including the intermetallics FePt3, CoPt, CuPt, and Cu3-Pt and the alloys Ag-Pt, Au-Pd, and Ni-Pt. The ternary intermetallic Ag2Pd3S can also be rapidly synthesized at low temperatures from a nanocomposite precursor comprised of Ag2S and Pd nanoparticles. Using this low-temperature solution-based approach, a variety of morphologically diverse nanomaterials are accessible: surface-confined thin films (planar and nonplanar supports), free-standing monoliths, nanomesh materials, inverse opals, and dense gram-scale nanocrystalline powders of intermetallic AuCu. Importantly, the multimetallic materials synthesized using this approach are functional, yielding a room- temperature Fe-Pt ferromagnet, a superconducting sample of Ag2Pd3S (Tc = 1.10 K), and a AuPd4 alloy that selectively catalyzes the formation of H2O2 from H2 and O2. Such flexibility in the synthesis and processing of functional intermetallic and alloy materials is unprecedented. [ABSTRACT FROM AUTHOR]

A new multistep approach was developed to synthesize atomically ordered intermetallic nanocrystals, using AuCu and AuCu3 as model systems. Bimetallic nanoparticle aggregates are used as precursors to atomically ordered nanocrystals, both to precisely define the stoichiometry of the final product and to ensure that atomic-scale diffusion distances lower the reaction temperatures to prevent sintering. In a typical synthesis, PVP-stabilized Au-Cu nanoparticle aggregates synthesized by borohydride reduction are collected by centrifugation and annealed in powder form. At temperatures below 175 °C, diffusion of Cu into Au occurs, and the atomically disordered solid solution CuxAu1-x exists. For AuCu3, nucleation occurs by 200 °C, and atomically ordered AuCu exists between 200 and 400 °C. For AuCu3, an AuCu intermediate nucleates at 200 °C, and further diffusion of Cu into the AuCu intermediate at 300 °C nucleates AuCu3. Atomically ordered AuCu and AuCu3 nanocrystals can be redispersed as discrete colloids in solution after annealing between 200 and 300 °C. [ABSTRACT FROM AUTHOR]

Amorphous tungsten phosphide (WP), which has been synthesized as colloidal nanoparticles with an average diameter of 3 nm, has been identified as a new electrocatalyst for the hydrogen-evolution reaction (HER) in acidic aqueous solutions. WP/Ti electrodes produced current densities of -10 mA cm-2 and -20 mA cm-2 at overpotentials of only -120 mV and -140 mV, respectively, in 0.50 M H2SO4(aq). [ABSTRACT FROM AUTHOR]

Integrating multiple materials in arbitrary arrangements within nanoparticles is a prerequisite for advancing many applications. Strategies to synthesize heterostructured nanoparticles are emerging, but they are limited in complexity, scope, and scalability. We introduce two design guidelines, based on interfacial reactivity and crystal structure relations, that enable the rational synthesis of a heterostructured nanorod megalibrary. We define synthetically feasible pathways to 65,520 distinct multicomponent metal sulfide nanorods having as many as 6 materials, 8 segments, and 11 internal interfaces by applying up to seven sequential cation-exchange reactions to copper sulfide nanorod precursors. We experimentally observe 113 individual heterostructured nanorods and demonstrate the scalable production of three samples. Previously unimaginable complexity in heterostructured nanorods is now routinely achievable with simple benchtop chemistry and standard laboratory glassware. [ABSTRACT FROM AUTHOR]

The article reports on the ZnO-templated Synthesis of Wurtzite-Type ZnS and ZnSe nanoparticles. It states that significant attention was given to wide bandgap semiconductor nanocrystals because of their size-dependent properties and diverse applications. The article shows that ZnO nanoparticles, which adopt the WZ structure, can serve as structural templates for the controllable formation of WZ-type ZnS and ZnSe.

The article offers information about a study conducted to explore the implications of the discovery that nanocrystalline intermetallics undergo facile solution-mediated reaction to form derivative phases. The discovery provides a robust toolkit for systematically modifying the compositions and structures of multi-metal nanocrystals. Along with the discovery is the uncovering of the conversion strategy which produces important compounds that are difficult to make by other methods.

The cover page of the journal "Angewandte Chemie" is presented.

The precise placement of different materials in specific regions of a nanocrystal is important for many applications, but this remains difficult to achieve synthetically. Here we show that regioselectivity during partial cation exchange reactions of metal chalcogenide nano-crystals emerges from crystallographic relationships between the precursor and product phases. By maximizing the formation of low-strain interfaces, it is possible to rationally integrate three distinct materials within uniform spherical and rod-shaped colloidal nanoparticles to produce complex asymmetric heterostructured isomers. Through sequential partial exchange of Cu+ in Cu1.8S nanocrystals with Zn2+ and Cd2+, five distinct ZnS/CdS/ Cu1.8S nanosphere and nanorod isomers are accessible. [ABSTRACT FROM AUTHOR]

Complex heterostructured nanoparticles with precisely defined materials and interfaces are important for many applications. However, rationally incorporating such features into nanoparticles with rigorous morphology control remains a synthetic bottleneck. We define a modular divergent synthesis strategy that progressively transforms simple nanoparticle synthons into increasingly sophisticated products. We introduce a series of tunable interfaces into zero-, one-, and two-dimensional copper sulfide nanoparticles using cation exchange reactions. Subsequent manipulation of these intraparticle frameworks yielded a library of 47 distinct heterostructured metal sulfide derivatives, including particles that contain asymmetric, patchy, porous, and sculpted nanoarchitectures. This generalizable mix-and-match strategy provides predictable retrosynthetic pathways to complex nanoparticle features that are otherwise inaccessible. [ABSTRACT FROM AUTHOR]

Interfaces between nanoscale solids can facilitate coupling between dissimilar materials, leading to emergent and synergistic properties as well as mix-and-match multifunctionality. Seeded-growth methods, whereby one material is grown directly off of the surface of another, can lead to the formation of hybrid nanoparticles containing such solid-state heterojunctions. Successfully applying seeded-growth methods to the synthesis of hybrid nanoparticles, however, requires a precise balance of competing reaction variables, which limits the scope of materials that can be routinely incorporated into them and, accordingly, the types of achievable interfaces. Here, we describe an alternate pathway that overcomes key limitations of seeded-growth methods by synthetically deconvoluting the formation of particle-particle interfaces and the incorporation of desired materials components. Readily accessible hybrid nanoparticles can be rationally modified using sequential anion and cation exchange reactions which transform them into derivative products that contain different constituent materials but retain the preprogrammed morphologies and interfaces. Using Pt-MnO heterodimers as a synthetic entryway, we demonstrate the synthesis of seven different derivative Pt-MaXy (M = metal, X = chalcogen) heterodimers through integrated ion exchange pathways. We also demonstrate that tunable domain sizes are retained during complete multistep material transformations and that partial exchanges can be used to introduce morphologically sophisticated features into hybrid nanoparticles, including core@shell components. The sequential ion exchange reactions can also be applied to different domains of three-component hybrid nanoparticles, demonstrated for the transformation of Fe3O4-Pt-MnO into FeSx-Pt-Cu2S. Finally, the hybrid nanoparticle ion exchange reactions proceed with retention of anion sublattice structure across the particle-particle interfaces, demonstrating that crystallographic orientation and domain alignment are preserved. Collectively, these results demonstrate the wide-ranging applicability of sequential ion exchange reactions to controllably access a diverse library of colloidal hybrid nanoparticles across a wide range of materials, morphologies, and interfaces. [ABSTRACT FROM AUTHOR]

The ability to selectively synthesize one particular polymorph in a solid-state system having multiple crystal structures with the same composition is important for accessing desired properties. Solutionmediated reactions, including anion and cation exchange, that chemically transform colloidal nanoparticles with preprogrammed structural features into targeted products have emerged as a powerful platform for predictably accessing metastable polymorphs. While nanocrystal ionexchange reactions that retain anion sublattice features are well known, analogous reactions that preserve cation sublattice features are much less common, and guidelines for predictably targeting such sublattice features are not well established. Here, we report that both anion and cation sublattice features--hexagonal close-packed anions and tetrahedrally coordinated cations-can be preserved during cation exchange of roxbyite-type Cu2-xS nanocrystals to selectively produce wurtzite-type CoS and MnS. These polymorphs, which are metastable in bulk systems, form relative to other accessible structures having cubic close-packed anions and/or octahedrally coordinated cations. To facilitate these transformations, the scope of existing nanocrystal cation-exchange reactions was expanded to include 3d transition metal systems that previously have not been investigated in depth. [ABSTRACT FROM AUTHOR]

Colloidal hybrid nanoparticles contain multiple domains that are directly fused together through a solid–solid interface, which facilitates synergistic interactions between the components that can lead to enhanced properties, as well as multifunctionality in a single particle. By nucleating one nanoparticle on the surface of another,a growing number of these hybrid nanoparticles can be synthesized. However, to rapidly expand the materials diversity of such systems,alternative routes to heterogeneous seeded nucleation are needed. Here, we show that solution-mediated chemical transformation reactions,which are well established for pseudomorphically transforming colloidal metal nanoparticles into derivative metal-containing phases, can also be applied to colloidal hybrid nanoparticles. Specifically, we show that Pt–Fe3O4heterodimers react with Pb(acac)2and Sn(acac)2at 180–200 °Cin a mixture of benzyl ether, oleylamine, oleic acid, and tert-butylamine borane to form PtPb–Fe3O4and Pt3Sn–Fe3O4heterodimers, respectively. This chemical transformation reaction introduces intermetallic and alloy components into the heterodimers,proceeds with morphological retention, and preserves the solid–solid interface that characterizes these hybrid nanoparticle systems. In addition, the PtPb–Fe3O4 heterodimers spontaneously aggregate to form colloidally stable (PtPb–Fe3O4 )n nanoflowers via a process that is conceptually analogous to a molecular condensation reaction. These reactions add to the growing toolbox of predictable manipulations of colloidal hybrid nanoparticles, ultimately expanding their materials diversity and range of potential applications. [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.

CuCo2S4 is an important mixed-metal spinel-type sulfide that is typically synthesized using high-temperature solid-state reactions, which produce agglomerated particles with low surface areas that are not optimal for applications such as heterogeneous catalysis. Here, we show that highly crystalline and nonagglomerated colloidal CuCo2S4 nanoparticles can be synthesized in solution at 200 °C, which is significantly lower than previously reported methods. The CuCo2S4 nanoparticles were found to be highly active electrocatalysts for the oxygen evolution reaction (OER) under strongly alkaline conditions (1.0 M KOH, pH 14), requiring an OER overpotential of 395 mV to produce a current density of 10 mA cm-2. X-ray photoelectron spectroscopy (XPS) studies showed evidence of oxide formation, suggesting, in conjunction with the observed electrocatalytic properties, that the mixed-metal sulfides may serve as precursors to oxides and/or hydroxides, which are likely to be the catalytically active species. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: The concept of nanocrystal conversion chemistry, which involves the use of pre-formed nanoparticles as templates for chemical transformation into derivative solids, has emerged as a powerful approach for designing the synthesis of complex nanocrystalline solids. The general strategy exploits established synthetic capabilities in simple nanocrystal systems and uses these nanocrystals as templates that help to define the composition, crystal structure, and morphology of product nanocrystals. This article highlights key examples of “conversion chemistry” approaches to the synthesis of nanocrystalline solids using a variety of techniques, including galvanic replacement, diffusion, oxidation, and ion exchange. The discussion is organized according to classes of solids, highlighting the diverse target systems that are accessible using similar chemical concepts: metals, oxides, chalcogenides, phosphides, alloys, intermetallic compounds, sulfides, and nitrides. [Copyright &y& Elsevier]

The article presents a study which examines the chemical synthesis of air-stable manganese (Mn) nanoparticles (NPs). A solution chemistry method for the synthesis of air-stable NPs of alpha-Mn is explored. Crystalline alpha-Mn with no evidence for crystalline manganese oxides was shown by powder x-ray diffraction.

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.

The article describes a simple kinetically controlled borohydride reduction process for synthesizing shape-controlled Indium nanocrystals at room temperature. According to the authors, these nanoparticles exhibit the expected surface plasmon resonance properties, as well as superconductivity with a higher critical field than bulk Indium.