Diffusion and seed shape: intertwined parameters in the synthesis of branched metal nanostructures

Single-Crystalline Body Centered FeCo Nano-Octopods: From One-Pot Chemical Growth to a Complex 3D Magnetic Configuration

Single crystalline magnetic FeCo nanostars were prepared using an organometallic approach under mild conditions. The fine-tuning of the experimental conditions allowed the direct synthesis of these nano-octopods with body-centered cubic (bcc) structure through a one-pot reaction, contrarily to the seed-mediated growth classically used. The FeCo nanostars consist of 8 tetrahedrons exposing {311} facets, as revealed by high resolution transmission electron microscopy (HRTEM) imaging and electron tomography (ET), and exhibit a high magnetization comparable with the bulk one (M_s = 235 A·m²·kg^-1). Complex 3D spin configurations resulting from the competition between dipolar and exchange interactions are revealed by electron holography. This spin structures are stabilized by the high aspect ratio tetrahedral branches of the nanostars, as confirmed by micromagnetic simulations. This illustrates how magnetic properties can be significantly tuned by nanoscale shape control.

Wavelength-Dependent Nonlinear Absorption in Palladium Nanoparticles

This paper aims to study the nonlinear absorption characteristics of palladium nanoparticles (PdNPs) at off-resonant wavelengths. For this purpose, multi-wavelength (500–650 nm) nanosecond Z-scan technique was used. The experimental results indicate that saturated absorption (SA) and the transition from SA to reverse saturated absorption (RSA) can occur, and depends on the excitation wavelength and energy. When the excitation wavelength is constant, with the increase of excitation energy, PdNPs change from SA to RSA. When the excitation energy is constant, with the excitation wavelength approaching surface plasmon resonance (SPR), PdNPs change from SA to RSA. This phenomenon of SA and RSA under multi-wavelength excitation in the off-resonant region provides a supplement for the systematic study of the nonlinear absorption of PdNPs.

Enriching the branching of Au@PdAu core–shell nanocrystals using a syringe pump: kinetics control meets lattice mismatch

Gold@palladium–gold nanocrystals with a tunable branched shape are prepared via seeded growth, where the use of a syringe pump allows the manipulation over reaction kinetics as coupled by surface diffusion and strain caused by lattice mismatch.

Kinetically Controlled Sequential Seeded Growth: A General Route to Crystals with Different Hierarchies

The organization of natural materials into hierarchical structures accounts for the amazing properties of many biological systems; however, translating the structural motifs present in such natural materials to synthetic systems remains difficult. Inspired by how nature creates materials, this work demonstrates that kinetically controlled sequential seeded growth is a general bottom-up strategy to prepare hierarchical inorganic crystals with distinct compositions and nanostructured forms. Specifically, 85 distinct hierarchical crystals with different shape-controlled features, compositions, and overall symmetries were readily achieved by altering the kinetics of metal deposition in sequential rounds of seeded growth. These modifications in the deposition kinetics were achieved through simple changes to the reaction conditions (e.g., pH or halide concentration) and dictate whether concave or convex features are produced at specific seed locations, much in the manner that the changing atmospheric conditions account for the hierarchical and symmetrical structures of snow crystals. As such, this work provides a general paradigm for the bottom-up synthesis of hierarchical crystals regardless of inorganic material class.

Toward greener methods of producing branched metal nanostructures

This review highlights the use of biogenic resources (i.e., plant extracts, microorganisms, and biomolecules) as green reagents for the production of technologically promising branched metal nanomaterials.

Heat generation by branched Au/Pd nanocrystals: influence of morphology and composition

Bimetallic gold-palladium particles were originally proposed as catalysts with tunable reaction rates. Following the development of synthesis routes that offer better control on the morphology and composition of the particles, novel optical sensing functionalities were more recently proposed. Since temperature is a fundamental parameter that interplays with every other proposed application, we studied the light-to-heat conversion ability of Au/Pd bimetallic nanoparticles with a regular octapodal shape. Both compositional (Au-to-Pd ratio) and structural (diagonal tip-to-tip distance and tip width) characteristics were screened and found to be essential control parameters to promote light absorption and efficient conversion into heat. Electromagnetic simulations reveal that the Pd content, and specifically its distribution inside the branched particle geometry, has a profound impact on the optical properties and is an essential criterion for efficient heating. Notably, the optical and photothermal responses are shown to remain stable throughout extended illumination, with no noticeable structural changes to the branched nanocrystals due to heat generation.

Anisotropic nanomaterials for shape-dependent physicochemical and biomedical applications

This review contributes towards a systematic understanding of the mechanism of shape-dependent effects on nanoparticles (NPs) for elaborating and predicting their properties and applications based on the past two decades of research. Recently, the significance of shape-dependent physical chemistry and biomedicine has drawn ever increasing attention. While there has been a great deal of effort to utilize NPs with different morphologies in these fields, so far research studies are largely localized in particular materials, synthetic methods, or biomedical applications, and have ignored the interactional and interdependent relationships of these areas. This review is a comprehensive description of the NP shapes from theory, synthesis, property to application. We figure out the roles that shape plays in the properties of different kinds of nanomaterials together with physicochemical and biomedical applications. Through systematic elaboration of these shape-dependent impacts, better utilization of nanomaterials with diverse morphologies would be realized and definite strategies would be expected for breakthroughs in these fields. In addition, we have proposed some critical challenges and open problems that need to be addressed in nanotechnology.

Thermal Stability of Gold/Palladium Octopods Studied in Situ in 3D: Understanding Design Rules for Thermally Stable Metal Nanoparticles

Multifunctional metal nanoparticles (NPs) such as anisotropic multimetallic NPs are crucial for boosting nanomaterial-based applications. Advanced synthetic protocols exist to make a large variety of such nanostructures. However, a major limiting factor for the usability of them in real life applications is their stability. Here, we show that Au/Pd octopods, eight-branched nanocrystals with O _h symmetry, with only a low amount of Pd exhibited a high thermal stability and maintained strong plasmon resonances up to 600 °C. Furthermore, we study the influence of the composition, morphology, and environment on the thermal stability and define key parameters for the design of thermally stable multifunctional NPs.

Surface versus solution chemistry: manipulating nanoparticle shape and composition through metal-thiolate interactions

Nanostructures with well-defined crystallite sizes, shapes, and compositions are finding use in areas such as energy, security, and even medicine. Seeded growth is a promising strategy to achieve shape-controlled nanostructures, where specific structural features are often directed by the underlying symmetry of the seeds. Here, thiophenol derivatives capable of different metal-thiolate interactions were introduced into the synthesis of Au/Pd nanostructures by seed-mediated co-reduction. Our systematic analysis reveals that the symmetry and composition of the bimetallic nanoparticles (NPs) can be tuned as a function of additive binding strength and concentration, with symmetry reduction observed in some cases. Furthermore, additives with both thiol and amine functionalities facilitate random branching on the octahedral seed. Significantly, this synthetic versatility arises because the thiophenol derivatives modify both the surface capping of the growing nanostructures and the local ligand environment of the metal precursors, highlighting how the dual roles of synthesis components can be exploited to achieve high quality bimetallic nanostructures.

DNA-Encoded Morphological Evolution of Bimetallic Pd@Au Core-shell Nanoparticles from a High-indexed Core

DNA-mediated synthesis of nanoparticles with different morphologies has proven to be a powerful method to synthesize and access many exclusive shapes and surface properties. While previous studies employ seeds that contain relatively low-energy facets, such as a simple cubic palladium seed in the synthesis of Pd-Au bimetallic nanoparticles, few studies have investigated whether DNA molecules can still exert their influence when the synthesis uses a seed that contains high-energy facets. Seeds that are enclosed by such high-energy facets or sites are known to act as easy nucleation sites in nanoparticles growth and could potentially suppress the effect of DNA. To answer this question, we herein report DNA-encoded control of morphological evolution of bimetallic Pd@Au core-shell nanoparticles from a concave palladium nanocube seed that contains high indexed facets. Based on detailed spectroscopic and SEM studies of time-dependent growth of the bimetallic nanoparticles, we found that each of 10-mer DNA molecules (T10, G10, C10 and A10) has a unique way of interacting with both the seed's surface and the precursor. Among them, the most important factor is the binding affinity of the nucleobase to the Pd surface, with the A10 possessing the highest binding affinity and thus capable of stabilizing the seed's high energy surfaces. Furthermore, for bases with lower binding affinity (T10, G10 and C10) than A10, the growth is completely dictated by the seed's surface energy initially, but the later growth can still be influenced by the different DNA sequences, resulting in four unique morphologically different Pd@Au bimetallic nanoparticles. The effect of these DNA molecules with medium binding affinity can only be observed when there is more deposition of Au. Based on the above results, a scheme for the DNA controlled growth is proposed. Together these results have provided insights into factors governing DNA-mediated growth of core-shell structures using seeds with high-energy sites, and the insights can readily be applied to other bimetallic systems that adopt seed-mediated synthesis.

Origin of symmetry breaking in the seed-mediated growth of bi-metal nano-heterostructures

Seed-mediated growth is the most general way to controllably synthesize bimetal nano-heterostructures. Despite successful instances through trial and error were reported, the way for second metal depositing on the seed, namely whether the symmetry of resulted nano-heterostructure follows the original crystal symmetry of seed metal, remains an unpredictable issue to date. In this work, we propose that the thermodynamic factor, i.e., the difference of equilibrium electrochemical potentials (corresponding to their Fermi levels) of two metals in the growth solution, plays a key role for the symmetry breaking of bimetal nano-heterostructures during the seed-mediated growth. As a proof-of-principle experiment, by reversing the relative position of Fermi levels of the Pd nanocube seeds and the second metal Au with changing the concentration of reductant (L-ascorbic acid) in the growth solution, the structure of as-prepared products successfully evolved from centrosymmetric Pd@Au core-shell trisoctahedra to asymmetric Pd-Au hetero-dimers. The idea was further demonstrated by the growth of Ag on the Pd seeds. The present work intends to reveal the origin of symmetry breaking in the seed-mediated growth of nano-heterostructures from the viewpoint of thermodynamics, and these new insights will in turn help to achieve rational construction of bimetal nano-heterostructures with specific functions.

Synthesis of Highly Uniform Nickel Multipods with Tunable Aspect Ratio by Microwave Power Control

As the importance of anisotropic nanostructures and the role of surfaces continues to rise in applications including catalysis, magneto-optics, and electromagnetic interference shielding, there is a need for efficient and economical synthesis routes for such nanostructures. The article describes the application of cycled microwave power for the rapid synthesis of highly branched pure-phase face-centered cubic crystalline nickel multipod nanostructures with >99% multipod population. By controlling the power delivery to the reaction mixture through cycling, superior control is achieved over the growth kinetics of the metallic nanostructures, allowing formation of multipods consisting of arms with different aspect ratios. The multipod structures are formed under ambient conditions in a simple reaction system composed of nickel acetylacetonate (Ni(acac)₂), oleylamine (OAm), and oleic acid (OAc) in a matter of minutes by selective heating at the (111) overgrowth corners on Ni nanoseeds. The selective heating at the corners leads to accelerated autocatalytic growth along the ⟨111⟩ direction through a "lightning rod" effect. The length is proprtional to the length and number of microwave (MW)-on cycles, whereas the core size is controlled by continuous MW power delivery. The roles of heating mode (cycling versus variable power versus convective heating) during synthesis of the materials is explored, allowing a mechanism into how cycled microwave energy may allow fast multipod evolution to be proposed.

Surface Passivation and Supersaturation: Strategies for Regioselective Deposition in Seeded Syntheses

Crystal growth theory predicts that heterogeneous nucleation will occur preferentially at defect sites, such as the vertices rather than the faces of shape-controlled seeds. Platonic metal solids are generally assumed to have vertices with nearly identical chemical potentials, and also nearly identical faces, leading to the useful generality that heterogeneous nucleation preserves the symmetry of the original seeds in the final product. Herein, we test the limits of this generality in the extreme of low supersaturation, in an effort to expand the methods available for inducing anisotropic overgrowth. We formulate a strategy for favoring localized deposition that differentiates between both different vertices and different edges or faces, i.e., regioselective deposition. Deposition followed a simple kinetic model for nucleation rate, depending on wetting, supersaturation, and temperature. We demonstrate our ability to independently study the effects of varying supersaturation and surface passivation. Regioselective heterogeneous nucleation was achieved at low supersaturation by a kinetic preference for high-energy defect-rich sites over lower-energy sites. This outcome was also achieved by using capping agents to passivate facet sites where deposition was not desired. Collectively, the results presented herein provide a model for breaking the symmetry of seeded growth and for achieving regioselective deposition.

Concave Platinum-Copper Octopod Nanoframes Bounded with Multiple High-Index Facets for Efficient Electrooxidation Catalysis

Multimetallic nanoframes with three-dimensional (3D) catalytic surfaces represent an emerging class of efficient nanocatalysts. However, it still remains a challenge in engineering nanoframes via simple and economical methods. Herein, we report a facile one-pot synthetic strategy to synthesize Pt-Cu nanoframes bounded with multiple high-index facets as highly active electrooxidation catalysts. Two distinct octopod nanoframes, namely, concave PtCu₂ octopod nanoframes (PtCu₂ CONFs) and ultrathin PtCu octopod nanoframes (PtCu UONFs) were successfully synthesized by simply changing the feeding Pt and Cu precursors. Interestingly, the PtCu₂ CONFs are constructed by eight symmetric feet with sharp tips, which are enclosed by high-index facets of n (111)-(111), such as {553}, {331}, and {221}. Benefiting from their 3D accessible surfaces and multiple high-index facets, the self-supported PtCu₂ CONFs catalysts exhibit excellent electrocatalytic performance and superior CO-tolerant ability. For methanol oxidation reaction, the PtCu₂ CONFs catalysts exhibit more than 7-fold increase in activities, 205 mV lower in the onset potential compared with commercial Pt/C. More importantly, when facing harsh electrochemical reaction conditions, the PtCu₂ CONFs are well-preserved in the catalytic activities, architectural features, and stepped surfaces. The PtCu UONFs with 12 ultrathin edges, however, suffer from breakdown. The present work provides guidelines for the rational design and synthesis of nanoframe catalysts with both high activity and stability.

Strain-induced Stranski-Krastanov growth of Pd@Pt core-shell hexapods and octapods as electrocatalysts for methanol oxidation

Bimetallic nanocrystals with a branched shape have received great interest as catalysts due to their unique structures and fascinating properties. However, the conventional synthetic approaches based on the island growth mode often lead to the dendritic nanostructures with inhomogeneous and uncontrolled branches. Here precise control over the number of branches has been realized in the deposition of Pt on Pd seeds through the Stranski-Krastanov growth mechanism. Based on such a growth mode, Pd@Pt core-shell hexapods and octapods have been generated by a seeded growth with Pd octahedra and cubes as the seeds, respectively. We found that Pt atoms are initially deposited on the side faces of Pd seeds through a layer-by-layer epitaxial growth in the presence of oleylamine (OAm), leading to a local strain focused at their corners. These strain-concentrated sites promote the subsequent island growth of Pt atoms at the corners of the Pd seeds, resulting in the Pd@Pt core-shell hexapods or octapods. Both the Pd@Pt core-shell hexapods and octapods exhibit the substantially enhanced catalytic properties in terms of activity and stability towards a methanol oxidation reaction (MOR) relative to the commercial Pt/C. Specifically, the Pd@Pt core-shell hexapods show the highest specific (1.97 mA cm^-2) activity and mass activity (0.52 mA μg_Pt^-1) for the MOR, which are 5.8 and 2.6 times higher than those of the commercial Pt/C, respectively. This enhancement can probably be attributed to their unique structures and the synergistic effect between Pt and Pd.

Multifaceted Gold-Palladium Bimetallic Nanorods and Their Geometric, Compositional, and Catalytic Tunabilities

Kinetically controlled, seed-mediated co-reduction provides a robust and versatile synthetic approach to multimetallic nanoparticles with precisely controlled geometries and compositions. Here, we demonstrate that single-crystalline cylindrical Au nanorods selectively transform into a series of structurally distinct Au@Au-Pd alloy core-shell bimetallic nanorods with exotic multifaceted geometries enclosed by specific types of facets upon seed-mediated Au-Pd co-reduction under diffusion-controlled conditions. By adjusting several key synthetic parameters, such as the Pd/Au precursor ratio, the reducing agent concentration, the capping surfactant concentration, and foreign metal ion additives, we have been able to simultaneously fine-tailor the atomic-level surface structures and fine-tune the compositional stoichiometries of the multifaceted Au-Pd bimetallic nanorods. Using the catalytic hydrogenation of 4-nitrophenol by ammonia borane as a model reaction obeying the Langmuir-Hinshelwood kinetics, we further show that the relative surface binding affinities of the reactants and the rates of interfacial charge transfers, both of which play key roles in determining the overall reaction kinetics, strongly depend upon the surface atomic coordinations and the compositional stoichiometries of the colloidal Au-Pd alloy nanocatalysts. The insights gained from this work not only shed light on the underlying mechanisms dictating the intriguing geometric evolution of multimetallic nanocrystals during seed-mediated co-reduction but also provide an important knowledge framework that guides the rational design of architecturally sophisticated multimetallic nanostructures toward optimization of catalytic molecular transformations.

Rational selection of halide ions for synthesizing highly active Au@Pd nanobipyramids

Highly active Au@Pd nanobipyramids were synthesized using Br⁻ ions as an appropriate growth modifier.

High yield synthesis of branched gold nanoparticles as excellent catalysts for the reduction of nitroarenes

Acetanilide was used for the synthesis of high quality branched gold NPs exhibiting outstanding catalytic activity toward nitroarenes' reduction.

Branched Ag nanoplates: synthesis dictated by suppressing surface diffusion and catalytic activity for nitrophenol reduction

Highly branched Ag nanoplates were achieved at extremely low Ag atoms surface diffusion rate, fulfilledviathe Cu under potential deposition.

In-Plate and On-Plate Structural Control of Ultra-Stable Gold/Silver Bimetallic Nanoplates as Redox Catalysts, Nanobuilding Blocks, and Single-Nanoparticle Surface-Enhanced Raman Scattering Probes

Noble metal bimetallic nanomaterials have attracted a great deal of attention owing to the strong correlation between their morphology and chemical and physical properties. Even though the synthetic strategies for controlling the shapes of monometallic nanomaterials such as gold (Au) and silver (Ag) are well-developed, limited advances have been made with Au/Ag bimetallic nanomaterials to date. In this work, we demonstrate a highly complex in-plate and on-plate structural control of Au/Ag bimetallic nanoplates (Au/AgBNPLs) in contrast to conventional, simply structured, 1D and 2D, branched, and polyhedral nanomaterials. The polymer used in the synthesis of seeds plays a critical role in controlling the structure of the Au/AgBNPLs. The Au/AgBNPLs exhibit exceptionally high chemical stability against various chemical etchants and a versatile catalytic reactivity with biologically and environmentally relevant chemical species. Significantly, the reversible assembly formation of the Au/AgBNPLs is demonstrated by carrying out the surface-functionalization of the materials with thiol DNA, emphasizing the potential applications of the Au/AgBNPLs in various diagnostic and therapeutic purposes. Finally, the surface-enhanced Raman scattering (SERS) properties of the Au/AgBNPLs are experimentally and theoretically investigated, demonstrating a substantial potential of the Au/AgBNPLs as single-nanoparticle SERS probes. Electron microscopy, UV-vis spectroscopy, selected area electron diffraction (SAED), and energy-dispersive X-ray (EDX) spectroscopy are employed to analyze the structure and composition of the Au/AgBNPLs at the atomic level.

Anisotropic Nanoparticles and Anisotropic Surface Chemistry

Anisotropic nanoparticles are powerful building blocks for materials engineering. Unusual properties emerge with added anisotropy-often to an extraordinary degree-enabling countless new applications. For bottom-up assembly, anisotropy is crucial for programmability; isotropic particles lack directional interactions and can self-assemble only by basic packing rules. Anisotropic particles have long fascinated scientists, and their properties and assembly behavior have been the subjects of many theoretical studies over the years. However, only recently has experiment caught up with theory. We have begun to witness tremendous diversity in the synthesis of nanoparticles with controlled anisotropy. In this Perspective, we highlight the synthetic achievements that have galvanized the field, presenting a comprehensive discussion of the mechanisms and products of both seed-mediated and alternative growth methods. We also address recent breakthroughs and challenges in regiospecific functionalization, which is the next frontier in exploiting nanoparticle anisotropy.

Stable ligand-free stellated polyhedral gold nanoparticles for sensitive plasmonic detection

Ligand-free stellated gold nanoparticles (AuStNPs) with well-defined octahedral (O(h)) and icosahedral (I(h)) core symmetries were prepared using hydrogen peroxide as a reducing agent. Only three reagents: gold precursor (HAuCl4), H2O2 and NaOH were required to form colloidally and chemically stable AuStNPs with a zeta-potential between -55 and -40 mV indicative of excellent charge stabilization. The size and degree of stellation of AuStNPs can be controlled by several synthetic parameters so that the localized surface plasmon resonance (LSPR) can be varied from ca. 850 nm in near-infrared (NIR) to ca. 530 nm. In particular, AuStNP size and LSPR tuning can be conveniently accomplished by iodide variation. The size distribution of AuStNPs was improved by nucleation with ascorbic acid, and the AuStNP size and degree of branching could be readily modified using arginine. AuStNPs are advantageous for SPR sensing, as it was demonstrated in the sensitive detection of not only thiols, such as ampicillin, but also iodide with the detection limit of 3.2 pM (0.4 ng L(-1)). The reported ligand-free stable AuStNPs thus should be very useful for biodiagnostics based on SPR sensing and potentially for SERS and hyperthermia therapy.

Shape-controlled synthesis of Au–Pd bimetallic nanocrystals for catalytic applications

This review describes recent progress in the design and synthesis of shape-controlled Au–Pd bimetallic NCs and their emerging catalytic applications.

Gold-copper nanostars as photo-thermal agents: synthesis and advanced electron microscopy characterization

Nanoalloys have emerged as multi-functional nanoparticles with applications in biomedicine and catalysis. This work reports the efficient production and the advanced transmission electron microscopy characterization of gold-copper pentagonal nanostars. The morphology of the branches is controlled by the adequate choice of the capping agent. When oleylamine is used rounded nanostars are produced, while pointed nanostars are obtained by using hexadecylamine. Both types of nanostars were proved to be thermally stable and could therefore be used as therapeutic agents in photo-thermal therapies as confirmed by the near-infrared absorption spectra.

Seeding a New Kind of Garden: Synthesis of Architecturally Defined Multimetallic Nanostructures by Seed-Mediated Co-Reduction

Bimetallic nanoparticles display unique optical and catalytic properties that depend on crystallite size and shape, composition, and overall architecture. They may serve as multifunctional platforms as well. Unfortunately, many routes toward shape and architecturally controlled bimetallic nanocrystals yield polydisperse samples on account of the challenges associated with homogeneously nucleating a defined bimetallic phase by co-reduction methods. Developed by the Skrabalak laboratory, seed-mediated co-reduction (SMCR) involves the simultaneous co-reduction of two metal precursors to deposit metal onto shape-controlled metal nanocrystalline seeds. The central premise is that seeds will serve as preferential and structurally defined platforms for bimetallic deposition, where the shape of the seeds can be transferred to the shells. With Au-Pd as a model system, a set of design principles has been established for the bottom-up synthesis of shape-controlled bimetallic nanocrystals by SMCR. This strategy is successful at synthesizing symmetrically stellated Au-Pd nanocrystals with a variety of symmetries and core@shell Au@Au-Pd nanocrystals. Achieving nanocrystals with high morphological control via SMCR is governed by the following parameters: seed size, shape, and composition as well as the kinetics of seeded growth (through manipulation of synthetic parameters such as pH and metal precursor ratios). For example, larger seeds yield larger nanocrystals as does increasing the amount of metal deposited relative to the number of seeds. This increase in nanocrystal size leads to red-shifts in their localized surface plasmon resonance. Additionally, seed shape directs the overgrowth process during SMCR so the resultant nanocrystals adopt related symmetries. The ability to tune structure is important due to the size-, shape- and composition-dependent optical properties of bimetallic nanocrystals. Using this toolkit, the light scattering and absorption properties of Au-Pd octopods, 8-branched nanocrystals, could be tuned and were shown to be highly sensitive to changes in refractive index. The refractive index sensitivity displayed a linear correlation to the localized surface plasmon resonance initial position, where the sensitivity is greater than that of monometallic Au structures. Due to their bimetallic composition and unique architecture enabled by SMCR, Au-Pd octopods are promising refractive index based sensors. This Account summarizes the underlying principles for synthesis of bimetallic nanocrystals by SMCR, which have been established by systematic manipulation of synthetic parameters in a model Au-Pd system. These principles are anticipated to be general to other bimetallic systems, allowing for the design and synthesis of new nanocrystals with fascinating optical and catalytic properties.

Anisotropically branched metal nanostructures

This tutorial review provides an essential introduction to colloidally prepared branched metal nanostructures and their utility in plasmonics, catalysis and biomedicine.

Synthesis of hollow and trimetallic nanostructures by seed-mediated co-reduction

Seed-mediated co-reduction coupled with galvanic replacement is a new route to structurally defined trimetallic nanoparticles.