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Surface-enhanced Raman spectroscopy (SERS) is a powerful molecular spectroscopy technique that combines Raman spectroscopy with nanostructured metallic surfaces to amplify the Raman signals of target molecules by more than 103. The high sensitivity of SERS poses a significant opportunity for pesticide detection in complex matrices at ultralow concentrations. In this study, we improved the SERS sensitivity for imidacloprid (IMD) by employing silver nanostars (AgNs) coated with gold nanostars (AuNs) as the SERS-active substrate. The SERS response towards IMD detection increased based on the combination of AuNs and AgNs on the substrate surface. The intensity of the SERS signal of IMD using the AuNs/AgNs substrate increased compared to using individual metal nanoparticle substrates. The excellent reproducibility of SERS intensity using the AuNs/AgNs substrate was achieved with a low relative standard derivative (RSD) of 4.87% for 20 different spots on the same sample and 5.19% for 20 different samples. This detection system can be used for multiple tests, which is crucial for the advancement of handheld sensors designed for field use, where minimal or no high-level technical support is accessible. This manuscript reports the first introduction of gold nanostars on silver nanostars surface as the Surface-enhanced Raman spectroscopy (SERS) active elements to increase the SERS response towards imidacloprid pesticide. This combination of two metal nanostars showed an enhancement in imidacloprid signal at low concentrations on the AuNs/AgNs surface when compared to the signal on the surface composed of a single type of metal nanostars. The substrates were shown to be stable over a month in storage and can be reused many times. (Image credit: N. Abu Bakar.) [ABSTRACT FROM AUTHOR]

In this paper, copper-gold and copper-silver bimetallic surface nanospheres were formed using ArF excimer laser irradiation with a wavelength of 193 nm and a duration of 15 ns on thin film samples consisting of two metal layers deposited on BK7 glass. The density and shape of the structures were obtained under different irradiation conditions. The optical properties, morphology, and stability of optimal copper-gold and copper-silver structures were compared. The results show that high-density copper-gold core-shell nanospheres with high optical response and stability are produced at a fluence of 150 mJ/cm2 and 5 laser pulses. Silver-copper nanostructures showed lower density, weaker optical response, and lower stability than other nanostructures. The obtained copper-gold nanostructures are suitable for use in plasmonic applications such as biosensors and surface-enhanced Raman spectroscopy.

This study addresses the potential of combining multiple electroless plating reactions for homogeneous decoration of three-dimensional carbon fibers (CFs) with shape-controlled AgNi and AgCu bimetallic nanostructures. Morphology, crystal structure, and composition of the obtained bimetallic nanostructures were systemically examined by various spectroscopic and microscopic techniques including scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The electrocatalytic performance of the synthesized materials was investigated for the oxygen evolution reaction (OER). AgCu and AgNi bimetallic surfaces showed superior activity and stability compared to pristine Ag, Ni, or Cu. These observed enhancements on the bimetallic nanostructures are attributed to the synergistic effect between the elements present. AgNi nanoplate-decorated CFs exhibited the highest activity toward OER, which is attributed to the key role of Ag in stabilizing and increasing the number of β-NiOOH surface sites, which are the most relevant OER-active Ni species. [ABSTRACT FROM AUTHOR]

Illumination of noble metal nanostructures by electromagnetic radiation induces coherent oscillations of conductive electrons on their surfaces. These coherent oscillations of electrons, also known as localized surface plasmon resonances (LSPR), are the underlying physical cause of the electromagnetic enhancement of Raman scattering from analytes located in a close proximity to the metal surface. This physical phenomenon is broadly known as surface-enhanced Raman scattering (SERS). LSPR can decay via direct interband, phonon-assisted intraband, and geometry-assisted transitions forming hot carriers, highly energetic species that are responsible for a large variety of chemical transformations. This review critically discusses the most recent progress in mechanistic elucidation of hot carrier-driven chemistry and catalytic processes at the nanoscale. The review provides a brief description of tip-enhanced Raman spectroscopy (TERS), modern analytical technique that possesses single-molecule sensitivity and angstrom spatial resolution, showing the advantage of this technique for spatiotemporal characterization of plasmon-driven reactions. The review also discusses experimental and theoretical findings that reported novel plasmon-driven reactivity which can be used to catalyze redox, coupling, elimination and scissoring reactions. Lastly, the review discusses the impact of the most recently reported findings on both plasmonic catalysis and TERS imaging.

Summary: Singlet oxygen (1O2) is extensively employed by reactive oxygen species (ROS)-based cancer therapies, such as photodynamic therapy (PDT) and chemodynamic therapy (CDT). However, the dependences of PDT on light and CDT on complex chemodynamic reactions greatly limit their 1O2-generating efficiencies. Here, we exploit strain and electronic effects to fabricate a bimetallic nanocatalyst by coating a gold nanorod (AuNR) with ~2 platinum (Pt) atomic layers (AuPt0.09), which efficiently generates 1O2 from ground-state oxygen (3O2) by electron-transfer-mediated spin reduction. Density functional theory reveals strain, and electronic effects promote the adsorption of 3O2 onto AuPt0.09, which dramatically enhances 1O2 generation and imparts AuPt0.09, the highest catalytic constant ever reported for 3,3′,5,5′-tetramethylbenzidine oxidation to the best of our knowledge. With a pH-dependent catalytic activity, AuPt0.09 realizes acidity-dependent antitumor effects both in vitro and in vivo, a proof-of-concept demonstration of autocatalytic bimetallic nanocatalyst for light-free oxygen sensitization therapy, which may open a new avenue for 1O2-centered therapeutics.

Abstract Non‐spherical Au/Ag nanoparticles can be generated by chemical reduction of silver ions in the presence of preformed gold nanoparticles. The process of particle formation can be controlled by concentrations of ligands and reducing agent. The formation of ellipsoidal, nanorod‐ and peanut‐shaped nanoparticles as well as of more complex fractal nanoassemblies can be explained by changes in particle surface state, electrochemical potential formation and particle‐internal self‐polarization effects. It is possible to create highly fractal nanoassemblies with sizes between the mid‐nanometer and the lower micrometer range. The assemblies are marked by high optical absorption and complex nano‐networks of very high surface‐to‐volume ratios and a granular base structure.

In this paper the process of the structure formation in the bimetallic nanosystem Au – Ag of the equiatomic type at different external pressures has been investigated. It has been found that the external pressure affects the process of formation of the bcc phase only slightly, as does the size factor as well. At the same time, the ratios between fcc, hcp and icosahedral phases can vary significantly, under influence of both the external pressure and thesize effect.

Cascade electrochemical reduction of CO2 has been investigated on nanostructured bimetallic gold-copper and silvercopper catalyst nanowire and foam electrode arrays. The bimetallic electrocatalysts allow for the overall carbon dioxide reduction reaction (CO2RR) to be performed, where CO2 to CO conversion occurring at silver (Ag) or gold (Au) is decoupled from conversion to multicarbon species at Cu. The catalyst fabrication methods permit the catalyst orientation to be controlled and thus investigation of catalyst order on the cascade process. Segmentation of bimetallic electrodes is most versatile for nanofoam arrays. Placement of an Ag foam beneath a Cu foam, where CO produced at Ag must pass through the Cu foam, results in an enhancement in methane, ethanol, and propanol production as compared to the reverse electrocatalyst ordering. [ABSTRACT FROM AUTHOR]

Bimetallic nanoparticles (BNPs) have attracted greater attention compared to its monometallic counterpart because of their chemical/physical properties. The BNPs have a wide range of applications in the fields of health, energy, water, and environment. These properties could be tuned with a number of parameters such as compositions of the bimetallic systems, their preparation method, and morphology. Monodisperse and anisotropic BNPs have gained considerable interest and numerous efforts have been made for the controlled synthesis of bimetallic nanostructures (BNS) of different sizes and shapes. This review offers a brief summary of the various synthetic routes adopted for the synthesis of Palladium(Pd), Platinum(Pt), Nickel(Ni), Gold(Au), Silver(Ag), Iron(Fe), Cobalt(Co), Rhodium(Rh), and Copper(Cu) based transition metal bimetallic anisotropic nanostructures, growth mechanisms e.g., seed mediated co-reduction, hydrothermal, galvanic replacement reactions, and antigalvanic reaction, and their application in the field of catalysis. The effect of surfactant, reducing agent, metal precursors ratio, pH, and reaction temperature for the synthesis of anisotropic nanostructures has been explained with examples. This review further discusses how slight modifications in one of the parameters could alter the growth mechanism, resulting in different anisotropic nanostructures which highly influence the catalytic activity. The progress or modification implied in the synthesis techniques within recent years is focused on in this article. Furthermore, this article discussed the improved activity, stability, and catalytic performance of BNS compared to the monometallic performance. The synthetic strategies reported here established a deeper understanding of the mechanisms and development of sophisticated and controlled BNS for widespread application.

• Recent fabrication strategies, characterization techniques, and benefits are analyzed. • Practical applications of bimetallic nanostructure integrated membranes are discussed. • BNPs are effective at removing inorganic, organic, and biological water contaminants. • Membrane-supported bimetallic with SR-AOPs alleviated fouling and NPs agglomeration. • Bottom-up approaches are useful for producing BNPs with precisely tuned properties. Advances in heterogeneous advanced oxidation processes are hindered by various challenges, such as mass transfer limitations, nanoparticle aggregation, short lifetimes of reactive oxygen species (ROS), and leaching of nanoparticles. Bimetallic nanoparticle-functionalized membranes coupled with advanced oxidation processes (BNPFM-AOPs) are the most suitable and efficient solutions because of their simultaneous destruction and mineralization of pollutants, facile separation and recovery of catalyst, affordability, microbe deactivation, and membrane antifouling properties. BNPFM-AOPs have improved oxidant-nanocatalyst interactions, ROS-pollutant interactions, and rapid ROS diffusion rates than conventional heterogeneous AOPs, resulting in increased ROS yields, reduced matrix effects, and faster degradation rates. This review overviews fabrication methods (blending, surface coatings, bottom-up synthesis, and in-situ synthesis), characterization techniques (composition, morphology, structure, and performance), and potential applications. A review of recent advances in oxidant activation and removal mechanisms for heavy metals, antibiotics, and organic pollutants is presented. It also highlights membrane fouling and cleaning mechanisms, reaction kinetics, and toxicity assessment. Furthermore, the scope, challenges, and recommendations are discussed. This study is anticipated to advance our understanding of BNPFM-SR-AOP chemistry, fabrication methods, characterization techniques, degradation rates, and toxicity. [ABSTRACT FROM AUTHOR]

Non‐spherical Au/Ag nanoparticles can be generated by chemical reduction of silver ions in the presence of preformed gold nanoparticles. The process of particle formation can be controlled by concentrations of ligands and reducing agent. The formation of ellipsoidal, nanorod‐ and peanut‐shaped nanoparticles as well as of more complex fractal nanoassemblies can be explained by changes in particle surface state, electrochemical potential formation and particle‐internal self‐polarization effects. It is possible to create highly fractal nanoassemblies with sizes between the mid‐nanometer and the lower micrometer range. The assemblies are marked by high optical absorption and complex nano‐networks of very high surface‐to‐volume ratios and a granular base structure. [ABSTRACT FROM AUTHOR]

Herein, comparison between eco-friendly homo-metallic (Ag) and hetero-metallic (Ag Au and Ag-Au-Pd) nanostructures in catalysis was studied. The homo-metallic and hetero-metallic nanostructures were greenly synthesized using Agar as nano-generator. The sequential reduction of metal ions to give homo- and hetero-metallic nanostructures was initially confirmed via UV–Visible spectra. Tracking of transmission electron microscope and zetasizer data showed that, all the produced nanostructures were well-dispersed and spherical in shape. Small-sized AgNPs with mean size of 9.1 nm were enlarged to 23.7 nm for Ag Au bimetallic nanostructure. While, trimetallic nanoshells of Ag-Au-Pd was diminished to be 13.6 nm. The FT-IR and 13CNMR spectral analyses were detected to investigate the reaction mechanism for synthesis of nanostructures. The catalytic performance of the synthesized nanostructures in degradation of methylene blue and methyl orange dyes was a strongly correlated to the composition of nanostructures. Half time of methylene blue and methyl orange degradation was diminished from 45.90 and 47.15 to 0.97 and 0.69 min by using trimetallic nanostructures as a catalyst, respectively. The current strategy can present an environmentally benign and valuable methodology for fabrication of hetero-metallic nanostructures with desirable size and have efficient catalytic activity. Unlabelled Image • Comparison between homo-metallic and hetero-metallic nanostructures in catalytic activity was studied. • Eco-friendly Ag, Ag Au and Ag-Au-Pd nanostructures were prepared with size of 9.1, 23.7 and 13.6 nm, respectively. • The catalytic activity of the nanostructures was strongly correlated to their composition. • The t 1/2 for dye degradation was reduced by 47.3–68.3 times at using Ag-Au-PdNPs as a catalyst. [ABSTRACT FROM AUTHOR]

The fluorescence of photosystem I (PSI) trimers in proximity to bimetallic plasmonic nanostructures have been explored by single-molecule spectroscopy (SMS) at cryogenic temperature (1.6 K). PSI serves as a model for biological multichromophore-coupled systems with high potential for biotechnological applications. Plasmonic nanostructures are fabricated by thermal annealing of thin metallic films. The fluorescence of PSI has been intensified due to the coupling with plasmonic nanostructures. Enhancement factors up to 22.9 and 5.1 are observed for individual PSI complexes coupled to Au/Au and Ag/Au samples, respectively. Additionally, a wavelength dependence of fluorescence enhancement is observed, which can be explained by the multichromophoric composition of PSI.

Structural engineering of nanomaterials offers a promising way for developing high-performance catalysts toward catalysis. However, the delicate modulation of thermodynamically unfavorable nanostructures with unconventional phases still remains a challenge. Here, the synthesis of hierarchical AuCu nanostructures is reported with hexagonal close-packed (2H-type)/face-centered cubic (fcc) heterophase, high-index facets, planar defects (e.g., stacking faults, twin boundaries, and grain boundaries), and tunable Cu content. The obtained 2H/fcc Au 99 Cu 1 hierarchical nanosheets exhibit excellent performance for the electrocatalytic CO 2 reduction to produce CO, outperforming the 2H/fcc Au 91 Cu 9 and fcc Au 99 Cu 1 . The experimental results, especially those obtained by in-situ differential electrochemical mass spectroscopy and attenuated total reflection Fourier-transform infrared spectroscopy, suggest that the enhanced catalytic performance of 2H/fcc Au 99 Cu 1 arises from the unconventional 2H/fcc heterophase, high-index facets, planar defects, and appropriate alloying of Cu. Impressively, the 2H/fcc Au 99 Cu 1 shows CO Faradaic efficiencies of 96.6% and 92.6% at industrial current densities of 300 and 500 mA cm -2 , respectively, as well as good durability, placing it among the best CO 2 reduction electrocatalysts for CO production. The atomically structural regulation based on phase engineering of nanomaterials (PEN) provides an avenue for the rational design and preparation of high-performance electrocatalysts for various catalytic applications., (© 2023 Wiley-VCH GmbH.)

Abstract Bimetallic nanostructures have emerged up as unique nano-objects due to the synergism between two metallic nanostructures. In the current approach, bactericide silver- gold bimetallic nanostructures have been fabricated using guar gum, which is employed as cluster growth adaptor. Silver‑gold bimetallic nanostructures were initially detected with the aid of UV–Visible spectrophotometer, where, the characteristic Surface Plasmon Resonance peak for bimetallic nanostructures was detected at 480–495 nm. Size controlling of nanostructures was achieved by interchanging the concentration of nano-metal precursors, their addition sequencing with strong alkali in reaction liquor, and temperature. According to transmission electron microscopic graphs and zetasizer data, silver‑gold bimetallic nanostructures are well-dispersed and spherical in shape. The as-mentioned tracking analyses confirmed that, the particle size for all the nanostructures were in range of 2.26 to 27.1 nm. All of the produced bimetallic nanostructures showed good stability with PdI ranged in 0.27–0.53. X-Ray diffraction analyses confirmed that, the manufactured bimetallic nanostructures were characterized by face cubic centered crystalline shape. According to FTIR, 1H NMR and 13C NMR spectral data, the mechanism of synthesis the as-required bimetallic nano-structures was elucidated and approved. The bactericidal action of the as-synthesized nanostructures is estimated to approve its compatibility to be applicable in various medical purposes. Graphical abstract Unlabelled Image Highlights • Bactericide Ag-Au bimetallic nano-objects were synthesized via sequential reduction technique. • Guar gum was employed as nanogenerator and cluster growth adaptor. • Size controlled Ag-Au bimetallic nano-objects (2.26–27.1 nm) were produced. • Spectral mapping data were detected for elucidation of reaction mechanism. • Synthesized bimetallic nanostructures exhibited good stability (PdI; 0.27–0.53). [ABSTRACT FROM AUTHOR]

1D metal nanostructures exhibit unique properties due to their high aspect ratio for use in many applications including electrocatalysis. This work develops a solution-based approach to 1D multimetal nanostructures with tunable surface structures by combining the two processes of coreduction and galvanic replacement. In this approach, noble metals of Pt and Ru are reduced in the presence of in situ formed Cu seeds. At high concentrations of noble metal precursors, coreduction dominates over galvanic replacement, leading to overgrowth of ultrafine, particulate, or branched structures on the surface of the 1D nanostructures. The surface roughness and composition can be tuned by varying the concentrations of noble metal precursors. The electrochemical reactivity is not only affected by the surface roughness (i.e., the size of particulates and the level of branches) but also the surface composition (i.e., the amount of Pt content). For trimetallic nanostructures, the alloy composition prevents the dissolution of Ru thereby improving electrocatalytic stability of the catalyst under acidic conditions. The structure-property study reveals that the surface structure plays an important role in tailoring the electrocatalytic property of a catalyst. [ABSTRACT FROM AUTHOR]

Bimetallic nanostructures (BNSs) are important components in various applications due to their elemental composition and morphology dependent catalytic, electronic and optical properties. In this paper, the systematic evolution of Au xPd1−x (gold–palladium) BNSs on sapphire (0001) is studied via the solid-state dewetting of sequentially deposited Au–Pd bilayers along with the systematic control of elemental composition, annealing temperature, and time. Through the annealing of Au xPd1−x bilayers at various temperatures between 400 and 900 °C, the fabrication of nanoparticles (NPs) on bilayer, voids, and Au–Pd BNSs are observed with various compositions (Au0.25Pd0.75, Au0.5Pd0.5, and Au0.75Pd 0.25). The evolution process of AuxPd1−x BNSs is systematically analyzed based on the interdiffusion of Au and Pd and surface energy minimization mechanism. Along with the increased Au composition, the rate of dewetting is enhanced, which resulted in the significantly larger layer- top bimetallic NPs, voids, and BNSs. Furthermore, with the control of annealing time between 0 and 3600 s, the shape of Au–Pd BNSs is transform from the elongated to the round NPs due to the gradually enhanced diffusion. The reflectance (UV–VIS–NIR) spectra show the tight correlation with the surface morphology of AuxPd1−x BNSs and the average reflectance is gradually decreased along with the increased annealing temperature and time. The dipolar resonance peaks in the NIR region reveal a gradual blue-shift along with the increased annealing time due to the NP size reduction. [ABSTRACT FROM PUBLISHER]

Abstract: Plasmonic sensors that make use of localized surface plasmon resonance provide an excellent platform for hydrogen sensing. In this work, large plasmonic red shifts are obtained on (Au nanobipyramid core)@(Pd shell) bimetallic nanostructures for hydrogen sensing. Au nanobipyramid@Pd nanostructures with different shell thicknesses are synthesized by varying the Pd precursor amount. The Au nanobipyramid@Pd nanostructures with thicker Pd shells are found to exhibit larger responses to hydrogen. The maximal plasmonic red shift reaches 97 nm at 4 vol% hydrogen concentration. The shell morphology of the Au nanobipyramid@Pd nanostructures is further optimized to improve the hydrogen sensing performance. With the optimized nanostructures, the maximal plasmonic red shift is improved to ≈140 nm at 2 vol% hydrogen concentration. Compared with the Au nanobipyramid@Pd nanostructures, Au nanobipyramid/AgPd nanostructures show smaller plasmonic red shifts under the same conditions. The highly enhanced plasmonic shifts and sensitivity to hydrogen make our Au nanobipyramid@Pd nanostructures highly promising for the development of optical hydrogen sensing devices. [ABSTRACT FROM AUTHOR]

The synthesis of anisotropic metal nanostructures is strongly desired for exploring plasmon-enabled applications. Herein, the preparation of anisotropic Au/SiO2 and Au/SiO2/Pd nanostructures is realized through selective silica coating on Au nanobipyramids. For silica coating at the ends of Au nanobipyramids, the amount of coated silica and the overall shape of the coated nanostructures exhibit a bell-shaped dependence on the cationic surfactant concentration. For both end and side silica coating on Au nanobipyramids, the size of the silica component can be varied by changing the silica precursor amount. Silica can also be selectively deposited on the corners or facets of Au nanocubes, suggesting the generality of this method. The blockage of the predeposited silica component on Au nanobipyramids enables further selective Pd deposition. Suzuki coupling reactions carried out with the different bimetallic nanostructures functioning as plasmonic photocatalysts indicate that the plasmonic photocatalytic activity is dependent on the site of Pd nanoparticles on Au nanobipyramids. Taken together, these results suggest that plasmonic hot spots play an important role in hot-electron-driven plasmonic photocatalysis. This study opens up a promising route to the construction of anisotropic bimetallic nanostructures as well as to the design of bimetallic plasmonic-catalytic nanostructures as efficient plasmonic photocatalysts. [ABSTRACT FROM AUTHOR]

The magnetically-assisted growth of the amorphous bimetallic iron–nickel wire-like nanostructures is presented in this work. The applied process is based on a simple reduction reaction of aqueous solutions containing Fe2+ and Ni2+ ions with NaBH4 in the presence of an external magnetic field of about 0.05 T. The morphology, chemical composition, and magnetic properties of as-prepared Fe–Ni nanostructures have been determined by means of scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffractometry, and vibrating sample magnetometry. The obtained experimental data indicate that the as-prepared samples exhibit quite complex architectures i.e., they comprise of nanoparticles aligned in almost straight lines. In addition, they reveal the typical core-shell structures where the amorphous bimetallic alloy cores are covered by thin amorphous oxide shells. In turn, the magnetic measurements show that the Fe–Ni wire-like nanostructures behave as typical ferromagnetic nanomaterials and their magnetic parameters like saturation magnetizations and coercivities are strictly dependent on their sizes and chemical compositions. [ABSTRACT FROM AUTHOR]

Bimetallic nanostructures with well-defined shapes have shown distinct and advantageous catalytic properties compared to their monometallic counterparts. The use of bimetallic electrocatalysts may improve activity and durability, in addition to the possibility of reducing the loading of precious metals. A variety of bimetallic nanocrystals with different shapes has been reported in recent years. Their activities toward electrochemical catalytic reactions such as oxygen reduction and alcohol oxidations have been intensively studied. In this review, we discuss some latest developments in the morphology-controlled synthesis of Pt- and Pd-based bimetallic nanocrystals with shapes such as nanodendrites, polyhedra, porous hollow structures, and core shells, as well as their applications as electrochemical catalysts.

Water-soluble Ag-Au bimetallic nanostructures were prepared via co-reduction and seed-mediated growth routes employing poly-(4-styrenesulfonic acid-co-maleic acid) (PSSMA) as both a reductant and a stabilizer. Ag-Au alloy nanoparticles were obtained by the co-reduction of AgNO and HAuCl, while Ag-Au core-shell nanostructures were prepared through seed-mediated growth using PSSMA-Au nanoparticle seeds in a heated AgNO solution. The optical properties of the Ag-Au alloy and core-shell nanostructures were studied, and the growth mechanism of the bimetallic nanoparticles was investigated. Plasmon resonance bands in the range 422 to 517 nm were observed for Ag-Au alloy nanoparticles, while two plasmon resonances were found in the Ag-Au core-shell nanostructures. Furthermore, discrete dipole approximation theoretical simulation was used to assess the optical property differences between the Ag-Au alloy and core-shell nanostructures. Composition and morphology studies confirmed that the synthesized materials were Ag-Au bimetallic nanostructures. [ABSTRACT FROM AUTHOR]

Silver nanostructures with narrow plasmon linewidths and good chemical stability are strongly desired for plasmonic applications. Herein, a facile method is discussed for the preparation of Ag nanostructures with narrow plasmon linewidths and improved chemical stability through Ag overgrowth on monodispersed Au nanobipyramids. Structural evolution from bipyramid through rice to rod is observed, indicating that Ag atoms are preferentially deposited on the side surfaces of Au nanobipyramids. The resultant (Au nanobipyramid)@Ag nanostructures possess high size and shape uniformities, and much narrower plasmon linewidths than other Ag nanostructures. The spectral evolution of the supported Ag nanostructures is ascertained by both ensemble and single-particle characterizations, together with electrodynamic simulations. Systematic measurements of the refractive index sensing characteristics indicate that Ag nanostructures in this study possess high index sensitivities and figure of merit (sensitivity divided by linewidth) values. Moreover, Ag nanostructures in this study exhibit greatly improved chemical stability. The superior sensing capability of Ag nanostructures in this study is further demonstrated by the detection of sulfide ions at a relatively low detection limit. Taken together, results of this study show that the Au-nano­bipyramid-supported Ag nanostructures will be an outstanding candidate for the design of ultrasensitive plasmonic sensing devices as well as for the development of other plasmon-enabled technological applications. [ABSTRACT FROM AUTHOR]

Abstract: We report the use of seed‐mediated growth for the facile synthesis of five‐fold twinned Pd nanorods with controlled diameters in the range of 6–16 nm and tunable lengths up to 81 nm. In this approach, the formation of decahedral seeds and their anisotropic growth could be deliberately performed under different conditions to obtain samples with high purity. Transmission electron microscopy studies revealed that the nanorods were formed through the deposition of Pd atoms onto the surfaces of decahedral seeds along the <110> direction. Subsequent mechanistic studies indicated that a combination of a proper reduction rate and an effective capping agent was crucial to the formation of Pd nanorods. With the use of these Pd nanorods as templates, we also demonstrated the synthesis of Pd–Pt bimetallic nanotubes, as well as Pd@Au and Pd@Ag core–sheath nanorods. [ABSTRACT FROM AUTHOR]

A study was carried on the photochemical reduction of CO using mesoporous TiO modified with bimetallic Au/Cu nanostructures. The bimetallic nanocomposites display greater activity than monometallic TiO/Au and TiO/Cu nanocomposites. An optimal gold/copper ratio exists, at which the rate of photocatalytic methane formation is greatest. The activity of the nanoheterostructures depends on the sequence of deposition of the metals and increases in the series TiO/Cu@Au < TiO/Au/Cu < TiO/Au@Cu. [ABSTRACT FROM AUTHOR]

Core-shell bimetallic Au@Ni nanoparticles, with gold cores and thin nickel shells with overall size less than 10 nm, are synthesized and stabilized in pure cubic (fcc) and hexagonal (hcp) phase. Due to their unique crystal, electronic, and geometric structure, they show interesting magnetic and chemical properties. The Au@Nifcc is magnetic, whereas Au@Nihcp is non-magnetic. Both the bimetallic nanostructures are stable to surface oxidation until 150 °C and show excellent catalytic activity for p-nitrophenol reduction reaction. [ABSTRACT FROM AUTHOR]