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The cations in the solution spontaneously exchange with the constituent atoms in metal nanoparticles, forming single-atom alloys (SAAs) catalysts. The prepared PdRu SAA catalyst exhibited superior activity than commercial Pt for methanol oxidation reaction.

Here, the influence of Batchelor vortex flow on the cocrystallization of caffeine (CAF) and maleic acid (MA) is studied and compared with that of turbulent eddy flow. Batchelor flow, induced in a r...

Due to their unique soft and complex structure, it has been difficult to analyze the exact crystal structure of layered double hydroxides (LDHs), which has been a major obstacle to understanding and improving the catalytic properties of LDHs. In this report, we present an analytical method to characterize the crystal structure of LDHs using Rietveld refinement, XPS, and XANES. Using this analytical method, we found that ZnCo LDH nanoplates prepared by a new facile synthetic route had a Zn3.1Co1.9Cl2(OH)8·H2O structure and contained a large portion of divalent Co cations, unlike the previously reported ZnCo LDHs. Thanks to this accurate crystal structure analysis, we found that the cause of the enhanced electrochemical properties of the ZnCo LDH nanoplates toward the oxygen evolution reaction was the large portion of divalent Co cations.

This study reports on the aqueous-phase synthesis of rhodium-silver (RhAg) bimetallic composite nanoparticles with a controllable Rh/Ag ratio. Due to the high cost of Rh compared with Ag, the RhAg nanoparticles were synthesized in two steps: the synthesis of Ag nanoparticles and the formation of a Rh-rich RhAg area on the surface of the Ag nanoparticles. Transmission electron microscopy and corresponding elemental mapping analyses exhibited that the synthesized 20 nm-sized quasi-spherical RhAg nanoparticles were composed of Ag-rich and Rh-rich area, respectively. Considering the amount of Rh used and productivity, the RhAg nanoparticles with a Rh content of 0.8% exhibited the best catalytic performance for the direct H2O2 generation reaction.

In this report, a Couette-Taylor (CT) reactor was applied as an effective continuous process for synthesizing copper sulfide nanoparticles. The rotational speed, mean residence time (MRT), and concentration of the feed solution were important control factors on the morphology and size control of the nanoparticles. Increasing the rotational speed from 80 rpm to 90 rpm changed the morphology of the synthesized nanoparticles from nanofibers to hexagonal nanoplates. Only Cu7S4 nanofibers were obtained in the batch reactor. Through various comparative experiments, we found that MRT and the feed solution concentration affect monomer concentration in the CT reactor, thus controlling the morphology and size of the nanoparticles.

We propose a novel high-throughput screening platform using a centrifugal microfluidic device for producing combinatorial tri-metallic catalysts. The centrifugal device was designed to perform 60 reactions under different conditions on a single device. As a model to search for an optimal tri-metallic catalyst, we synthesized a variety of Pd@AuPt nanoparticles (NPs), in which Pd nanocubes served as a core, and Au and Pt atoms formed a shell. The centrifugal microfluidic device was etched on the top and bottom sides, in which two zigzag-shaped microchannels were patterned on the top side, and 60 reaction chambers were fabricated on the bottom side. Through the sophisticated zigzag-shaped microchannels, Pt2+ ion and Pd nanocube solutions were injected into the channel in one shot, and the centrifugal force equally and automatically divided the injected solutions into 60 aliquots during the rotation. By controlling the sophisticated channel dimensions and designing the passive valve structure, the Pt2+ ion, Pd nanocube, and Au3+ solutions were loaded into the reaction chamber in sequential order depending on the programmed rotational direction and speed. Therefore, the ratio of Au to Pt to synthesize Pd@AuPt core–shell NPs was changed from 0.028 : 1 to 12 : 1, and accordingly, the resultant 60 types of Pd@AuPt catalysts presented with different ratios of metal atom compositions. Then, we screened the catalytic activity of the Pd@AuPt NPs for generating H2O2 according to the degree of coating of Au and Pt, and the Pd@AuPt catalyst with the Au/Pt ratio at 0.5 turned out to be the most effective.

Here, a novel, versatile synthetic strategy to fabricate a yolk-shell structured material that can encapsulate virtually any functional noble metal or metal oxide nanocatalysts of any morphology in a free suspension fashion is reported. This strategy also enables encapsulation of more than one type of nanoparticle inside a single shell, including paramagnetic iron oxide used for magnetic separation. The mesoporous organosilica shell provides efficient mass transfer of small target molecules, while serving as a size exclusion barrier for larger interfering molecules. Major structural and functional advantages of this material design are demonstrated by performing three proof-of-concept applications. First, effective encapsulation of plasmonic gold nanospheres for localized photothermal heating and heat-driven reaction inside the shell is shown. Second, hydrogenation catalysis is demonstrated under spatial confinement driven by palladium nanocubes. Finally, the surface-enhanced Raman spectroscopic detection of model pollutant by gold nanorods is presented for highly sensitive environmental sensing with size exclusion.

We report a facile one-pot aqueous-phase synthesis of PdAu bimetallic nanoparticles with different Pd/Au ratio. The synthesis was conducted by co-reduction of Pd and Au precursor using ascorbic acid as a reducing agent and in the presence of polyallylamine hydrochloride (PAH). By high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectrometry (EDS) analyses, we found that the synthesized nanoparticles had an onion-like core/shell/shell/shell structure with Au-rich core, Pd-rich shell, Au-rich shell, and Pd shell, respectively. We also investigated the catalytic performance of the synthesized PdAu nanoparticles toward hydrogen peroxide generation reaction.

We report the external field-guided shape transformation of magnetite-polymer composite particles that play multiple roles in heterogeneous chemical reactions, such as catalysts, catalyst supports, and micro-stirrers. A microfluidic method was used to generate monodispersed emulsion droplets composed of polystyrene, magnetite nanoparticles (MNPs), and chloroform. While the solvent in the droplets was dried in the presence of an external magnetic field, the emulsion droplets were deformed or elongated along the field direction, consequently leading to magnetically responsive particles with anisotropic shape after complete removal of the solvent. Coarse-grained molecular dynamic simulations demonstrated that the shape deformation was due to destabilization of the MNPs upon solvent drying and migration of the aggregated MNPs in the polymer matrix along the external field. The particle shape could be readily tunable by modulating the field strength and direction as well as the concentrations of the MNPs and polymer. We further revealed that these magnetic anisotropic particles coated with palladium nanoparticles could be used as catalysts, catalyst supports, micro-stirrers when the particles were dispersed in a small confined volume of a catalytic precursor solution.

The efficiency of two prototype catalysis systems using palladium (Pd)-coated microparticles was investigated with regard to the recovery and recyclability of the catalytic particles. One such system was the interface-adsorption method, in which polymer particles coated with Pd nanoparticles strongly and irreversibly attach to the oil-water interface. Due to the irreversible adsorption of the catalytic particles to the interface, particle loss was completely prevented while mixing the aqueous solution and while collecting the products. The other system was based on the magnetic field-associated particle recovery method. The use of polymeric microparticles containing Pd nanoparticles and magnetite nanoparticles accelerated the sedimentation of the particles in the aqueous phase by applying a strong magnetic field, consequently suppressing drainage of the particles from the reactor along the product stream. Upon multiple runs of the catalytic reactions, it was found that conversion does not change significantly, demonstrating the excellent recyclability and performance efficiency in the catalytic processes.

As a joint investigation principle using experimental and theoretical approaches, we report that the anisotropic growth of Pt on Pd nanocubes significantly promotes the direct synthesis of hydrogen peroxide (H2O2) from hydrogen (H2) and oxygen (O2). The superior H2O2 productivity of the anisotropic Pd@Pt core@shell nanocrystals results from the enhanced H2 conversion and the H2O2 selectivity compared to Pd and Pt. From the joint investigation, during the anisotropic growth of the Pd@Pt nanocrystals, high-index facets such as (2 1 0) are generated, and they provide numerous active sites for hydrogen dissociation. Notably, even the nano-catalyst is enclosed by Pt shell, the high-index facets are favorable for opening a new route for hydrogen dissolution into the Pd bulk lattices of the Pd@Pt nanocrystals, in which the dissolved hydrogen can react with chemisorbed O2 over the nanocrystals to form H2O2. This mechanism is suggested by a hydrogen temperature programmed reduction (H2-TPR) analysis, in situ transmission electron microscopy (TEM), and density functional theory (DFT) calculations. This study provides another option to improve the catalytic performance of core@shell nanocrystals via the generation of high-index facets through anisotropic growth of nanocrystals, in addition to the well-known strain and charge transfer effects. We expect that the anisotropic growth approach could be extended to other catalytic reactions.

Metal and oxide nanoparticles (NPs) are attracting extensive attention in biomedical applications, including bioimaging and drug delivery. However, it is difficult to use these NPs as therapeutic agents for specific cell and tissue treatments because of limitations such as material oxidization and cell toxicity. Herein, we synthesized Cu-based angiogenic metal nanoparticles (Cu-AMNs), using a galvanic replacement reaction of Cu NPs and Au precursor, which stabilized and upregulated intracellular behaviors in human adipose-derived stem cells (hADSCs). Our novel therapeutic Cu-AMNs showed remarkable advantages in cell treatment, such as low mitochondrial damage, reduced ATP consumption, decreased cytotoxicity, mild reactive oxygen species generation with enhanced angiogenic paracrine factor secretion, and improved hypoxia inducible factor-1 alpha (HIF-1α) expression. Through the improved expression of HIF-1α, vascular endothelial growth factor (VEGF) secretion was prolonged for 3 days, even in re-attached hADSCs. In addition, Cu-AMNs improved other angiogenic factors and the amount of exocytosed Cu from hADSCs, resulting in strong development of tubular formation by human umbilical vein endothelial cells in vitro. Finally, transplantation of Cu-AMN-treated hADSCs in mice led to a significant in vivo increase in angiogenesis and blood perfusion in a mouse hindlimb ischemia model compared with conventional hADSC therapy.

Electrochemical activity and stability depend on the composition and morphology of nanocrystals. Mn3O4 nanoplates, Mn2O3 nanoplates, and porous Mn2O3 nanoplates were synthesized by heat treatment of Mn-glycolate nanoplates prepared by the wet-chemical method. In this research, the morphology and composition of the nanoplates could be easily controlled by varying the annealing temperature. The synthesized porous Mn2O3 nanoplates exhibited better electrocatalytic activities compared with Mn3O4 and Mn2O3 nanoplates, as similar as commercial IrO2 catalyst.

Pd@Pt core–shell nanocubes with a partially covered Pt shell on the Pd nanocubes were synthesized by a direct seed-mediated growth method without a washing process. The FAO activity of Pd@Pt 0.4 at% was 4.3 times and 2.2 times higher than that of Pd cubes and commercial Pt/C, respectively.

Facile synthesis and electrochemical performance of a Co3O4 nanoparticles/porous carbon composite used as an anode in Li-ion batteries is reported in this work. Co3O4 nanoparticles (5-10 nm in size) were embedded in a disordered porous carbon network using a simple template-free chemical method. The synthesized composite work well as an anode material for Li-ion batteries by delivering stable cycle life and highly reversible capacities of 480 mAhg-1 at 500mAg-1, which is higher than that of commercially available graphite electrodes and is comparable to values reported for Co3O4/graphene composites.

We investigated the effect of Fe3O4 nanoparticle orientation on the magnetic properties of hybrid polymer nanocomposite thin films. A multilayer thin film consisting of alternating layers of polymers and assembled iron oxide nanoparticles was prepared by spin coating and Langmuir–Blodgett techniques. Transmission electron microscopy and neutron reflectivity measurements were employed to determine structural information related to the lateral orientation of the Fe3O4 nanoparticle monolayer and the layered architecture along the depth of the multilayer, respectively. The magnetic properties of the hybrid multilayer were characterized by SQUID magnetometry and compared with the properties of a spin-coated polymer nanocomposite thin film containing homogenously dispersed Fe3O4 nanoparticles. We found that the closely-packed monolayer structure of the Fe3O4 nanoparticles changed the magnetic properties on account of the dipolar interactions between particles, whereas the homogeneously-dispersed nanoparticles embedded in the polymer matrix exhibited zero remanent magnetization and coercivity due to isolation of the nanoparticles and lack of dipolar interactions.

Here, we report a simple and fast synthetic route to Ag/AgBr hybrid nanostructures prepared by reducing AgBr nanoparticles synthesized by the reaction of Ag+ with Br− in the presence of polyethyleneimine (PEI). By controlling the experimental conditions including reaction temperature and amount of reducing agent, we could easily control the morphology and composition of a variety of Ag/AgBr hybrid nanostructures including Ag nanoparticles decorated with AgBr nanoparticles and hollow cage-like Ag-rich nanostructures. The Ag/AgBr hybrid nanostructures exhibited enhanced photocatalytic activity and recyclability for decomposing methylene blue (MB) under visible-light illumination because of a small bandgap (2.6 eV) and strong SPR effect. In particular, we found that the Ag/AgBr hybrid nanostructures showed a photocatalytic reaction rate that was 1000 times faster than commercial TiO2 (P-25). In addition, the Ag/AgBr hybrid nanostructures had a higher photocatalytic activity compared to Ag/AgCl hybrid nanostructures towards the decomposition of methyl orange (MO) under visible light illumination.

We report the colloidal synthesis of rare earth oxide nanoplates with square and disk shapes using thermal decomposition of Ln(CH3CO2)3·xH2O in the presence of a mixture of oleylamine and oleic acid (Ln=La, Pr, Nd, Dy, Er, and Y). In this synthesis, oleylamine plays an important role in the formation of ultra-thin nanoplates with thickness of 1.1 nm, which corresponds to a single unit cell dimension of rare earth oxides, and oleic acid serves as a capping agent for the formation of nanoplates having nano-sized side dimension (around 15-40 nm). By varying the rare earth precursors, we obtained square-shaped nanoplates (La2O3, Pr2O3, and Nd2O3) and disk-shaped nanoplates (Dy2O3, Er2O3, and Y2O3), respectively, confirming that our synthesis could be extended to the synthesis of various rare earth oxide nanoplates.

Synthesizing Cu nanocrystals with tunable sizes in the sub-100 nm regime and good uniformity is essential for their applications in microelectronics. In this paper, we demonstrate a facile and scalable synthetic route to uniform Cu nanocrystals with tunable sizes in the range of 20–100 nm based on an ethylene glycol (EG)-assisted synthetic method with appropriate alkylamine and fatty acid as surfactant and co-surfactant, respectively. In this approach, the size of Cu nanocrystals could be readily controlled by varying alkyl chain length of alkylamine, fatty acid, or both. We also demonstrate that these Cu nanocrystals can be successfully applied to the fabrication of solution-processed electrodes for organic field-effect transistors with reasonably high hole mobility.

This work describes a simple and aqueous-phase route for the synthesis of Cu nanowires (Cu NWs) having a long length of 140−180 μm, a high aspect ratio of more than 350, and long-term stability. High-quality Cu NWs were synthesized by reduction of CuCl2 with ascorbic acid in the presence of branched polyethyleneimine (BPEI) in an aqueous solution at 90 °C. The synthesized uniform Cu NWs showed long-term stability without the formation of Cu oxides on the surface of the NWs after being stored at room temperature for 40 days. Interestingly, we found that Cl− in the reacting solution played a key role in the formation of long Cu NWs. We also investigated the influence of various experimental conditions including the weight ratio of BPEI/CuCl2, the pH of the reacting solution, and the reaction temperature on the length, morphology, and stability of Cu NWs.

We describe a simple, aqueous-phase route to the synthesis of metal nanoparticles including Pt, Pd, Ru, and Au based on the aqueous-phase reduction of metal salts with NaBH4. In this approach, various phosphates were applied as new type of stabilizers for the synthesis of metal nanoparticles thanks to its negatively charged functional group (PO−).

Colloidal nanosheets of nickel-manganese layered double hydroxides (LDHs) have been synthesized in high yields through a facile reverse micelle method with xylene as an oil phase and oleylamine as a surfactant. Electron microscopy studies of the product revealed the formation of colloidal nanoplatelets with sizes of 50-150 nm, and X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy studies showed that the Ni-Mn LDH nanosheets had a hydrotalcite-like structure with a formula of [Ni3 Mn(OH)8 ](Cl(-) )⋅n H2 O. We found that the presence of both Ni and Mn precursors was required for the growth of Ni-Mn LDH nanosheets. As pseudocapacitors, the Ni-Mn LDH nanosheets exhibited much higher specific capacitance than unitary nickel hydroxides and manganese oxides.

We describe a simple method for synthesizing mesoporous silica-coated luminescent europium-doped gadolinium vanadate (GdVO4:Eu3+@mSiO2) nanoparticles. Their biomedical applications as a potential imaging nanoprobe for both fluorescence imaging and magnetic resonance imaging (MRI) and as a simultaneous anti-cancer drug delivery vehicle are also discussed. Eu3+ doped GdVO4 nanoparticles exhibit strong red photoluminescence and the Gd3+ in GdVO4 can be used as a T1 contrast agent for MRI. T1-weighted MR contrast enhancement as well as sustained intracellular drug delivery can be achieved by the mesoporous silica layer coating onto a single nanoparticle. Enhanced T1 MR contrast was proven by relaxometric studies on water access to the paramagnetic core. GdVO4:Eu3+@mSiO2 nanoparticles as a new type of theragnostic (imaging and treatment) agent can provide new opportunities in a cancer treatment.

A simple aqueous-phase route to the synthesis of ruthenium (Ru) nanoparticles with size in the sub-2-nm regime was prepared by reducing RuCl3 with NaBH4 as a reducing agent in the presence of 6-aminohexanoic acid (AHA) as a capping agent. We found that AHA plays a key role in the formation and distribution of ultrasmall Ru nanoparticles on inorganic supports, with its amine and carboxyl groups serving as a surface-capping agent for the Ru nanoparticles and an anchor to inorganic supports, respectively. The catalytic activity of the size-controlled Ru nanoparticles with sub-2-nm size on various supports, such as TiO2, CeO2, and Vulcan carbon, revealed that a strong metal–support interaction of Ru nanoparticles, especially on carbon support, is responsible for a higher CH4 selectivity during Fischer–Tropsch synthesis.

We present the pairwise interaction behaviour of colloids confined to two-dimensional (2D) colloidal cages using optical laser tweezers. A single probe particle inside hexagonal cage particles at a planar oil-water interface is allowed to diffuse freely and the spring constant is extracted from its trajectories. To evaluate the effect of multibody interactions, the pair interactions between the probe particle and each cage particle are directly measured by using optical tweezers. Based on pairwise additivity, Monte Carlo simulations are used to compare the values of the spring constant obtained from experiments and simulations. We find that the multibody interactions negligibly occur and thus the particle interactions confined to such colloidal cages are highly pairwise. This work demonstrates that the use of the pairwise assumption in numerical simulations is rational when interparticle repulsive interactions are sufficiently strong, such as the particle interactions at fluid-fluid interfaces.

Uniform 3 nm-sized ceria nanoparticles can protect against ischemic stroke by scavenging reactive oxygen species (ROS) and reducing apoptosis. PEGylated ceria nanoparticles showed protective effects against ROS-induced cell death in vitro. Optimal doses of ceria nanoparticles reduced infarct volumes and the rate of ischemic cell death in vivo.

Noble-metal nanocrystals with well-defined and controllable morphologies are of great importance to applications in catalysis, plasmonics, and surface-enhanced spectroscopy. Many synthetic approaches have been demonstrated for controlling the growth habit and thus morphology of metal nanocrystals, but most of them are based on a thermodynamic approach, including the use of a capping agent. While thermodynamic control has shown its power in generating nanocrystals with a myriad of different morphologies, it is ultimately limited by the obligation to minimize the surface energy of a system. As a result, it is impractical to use thermodynamic control to generate nanocrystals having high-energy facets and/or a negative curvature. Using rhodium as an example, here we demonstrate a general method based on kinetic control with a syringe pump that can be potentially extended to other noble metals and even other solid materials. For the first time, we were able to produce concave nanocubes with a large fraction of {110} facets and octapods with a cubic symmetry in high yields by simply controlling the injection rate at which the precursor was added into the reaction solution. The concave nanocubes with {110} facets and a unique cavity structure on the surface are important for a variety of applications.

The nanoparticle (NP) synthesis undergoes stepwise processes starting from the input metal ions: nucleation, coalescence, ripening, and growth. Considering the whole process is completed in a very short time, the conventional flask-scale method, which requires at least minutes, is not adequate to trace the mechanism of NP nucleation. In this study, a microfluidic droplet generator is developed, which is capable of in situ sol-gel polymerization for synthetic reaction quenching. As a model, palladium (Pd) NPs are synthesized within microdroplets, and the reaction time is controlled by tuning the length of the microchannel. In the microfluidic design, the outmost microchannel is incorporated, in which tetraethyl orthosilicate (TEOS) dissolved in ethanol is injected. The generated droplets are merged to the outmost flow under the variety of time interval (50 to 5,000 ms), so that the tens of milliseconds observation on NP nucleation is conducted via flash-like sol-gel quenching. Based on the result analysis, the seeds of Pd NPs have undergone slight size fluctuation and then a thermodynamically stable aggregation/coalescence step within 5 s before moving into the growth stage. This microfluidic platform permits the study of the fundamental and initial stage of the NP synthesis, which cannot be approached by the conventional methodology.

We report a novel and facile method for the synthesis of manganese oxide (Mn3O4) nanocrystals with various sizes and shapes. Mn3O4 nanocrystals were synthesized via a reaction of manganese(II) acetate with water in xylene in the presence of surfactants at the temperature of as low as 90 °C in air atmosphere. Structural characterizations revealed that the synthesized nanocrystals were tetragonal Mn3O4 structure and that they were highly crystalline in spite of the low reaction temperature. The size and shape of the nanocrystals were readily controlled by varying the experimental conditions such as precursors, surfactants, and injection temperature of water. Nanoplates with a thickness of 5 nm and side dimensions of 9, 15, and 22 nm were synthesized using oleylamine as the surfactant. When carboxylic acid was used as the cosurfactant along with oleylamine, spherical nanocrystals were obtained with sizes of 5.5, 6.2, 7.2, 8.5, and 15 nm. Interesting anisotropic nanostructures including nanowires and nanokite...

Uniformly sized silica-coated magnetic nanoparticles (magnetite@silica) are synthesized in a simple one-pot process using reverse micelles as nanoreactors. The core diameter of the magnetic nanoparticles is easily controlled by adjusting the w value ([polar solvent]/[surfactant]) in the reverse-micelle solution, and the thickness of the silica shell is easily controlled by varying the amount of tetraethyl orthosilicate added after the synthesis of the magnetite cores. Several grams of monodisperse magnetite@silica nanoparticles can be synthesized without going through any size-selection process. When crosslinked enzyme molecules form clusters on the surfaces of the magnetite@silica nanoparticles, the resulting hybrid composites are magnetically separable, highly active, and stable under harsh shaking conditions for more than 15 days. Conversely, covalently attached enzymes on the surface of the magnetite@silica nanoparticles are deactivated under the same conditions.

A simple and fast synthetic route to ultra-highly concentrated silver nanoparticles with long-term stability by reducing AgNO3 with ascorbic acid in the presence of polyethyleneimine (PEI) as a stabilizer in an aqueous phase is reported. The concentration of silver precursor was as high as 2000 mm (200 g of Ag nanoparticle per liter of water) and the reaction time was less than 10 min. The resulting silver nanoparticles show long-term stability after two months of storage at room temperature without any signs of particle aggregation or precipitation in an aqueous phase. The successful ligand exchange of PEI-stabilized silver nanoparticles to polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) without particle aggregation is also demonstrated. In addition, the catalytic activities of silver nanoparticles stabilized by various stabilizers prepared by the ligand exchange method was investigated. The PEI-stabilized silver nanoparticles exhibited a higher stability than those of PEG- and PVP-stabilized silver nanoparticles in the diffusion-controlled catalytic reduction of 4-nitrophenol to 4-aminophenol by NaBH4 .

We report on the synthesis of semiconductor nanocrystals of PbS, ZnS, CdS, and MnS through a facile and inexpensive synthetic process. Metal-oleylamine complexes, which were obtained from the reaction of metal chloride and oleylamine, were mixed with sulfur. The reaction mixture was heated under appropriate experimental conditions to produce metal sulfide nanocrystals. Uniform cube-shaped PbS nanocrystals with particle sizes of 6, 8, 9, and 13 nm were synthesized. The particle size was controlled by changing the relative amount of PbCl(2) and sulfur. Uniform 11 nm sized spherical ZnS nanocrystals were synthesized from the reaction of zinc chloride and sulfur, followed by one cycle of size-selective precipitation. CdS nanocrystals that consist of rods, bipods, and tripods were synthesized from a reaction mixture containing a 1:6 molar ratio of cadmium to sulfur. Spherical CdS nanocrystals (5.1 nm sized) were obtained from a reaction mixture with a cadmium to sulfur molar ratio of 2:1. MnS nanocrystals with various sizes and shapes were synthesized from the reaction of MnCl(2) and sulfur in oleylamine. Rod-shaped MnS nanocrystals with an average size of 20 nm (thickness) x 37 nm (length) were synthesized from a 1:1 molar ratio of MnCl(2) and sulfur at 240 degrees C. Novel bullet-shaped MnS nanocrystals with an average size of 17 nm (thickness) x 44 nm (length) were synthesized from the reaction of 4 mmol of MnCl(2) and 2 mmol of sulfur at 280 degrees C for 2 h. Shorter bullet-shaped MnS nanocrystals were synthesized from a 3:1 molar ratio of MnCl(2) and sulfur. Hexagon-shaped MnS nanocrystals were also obtained. All of the synthesized nanocrystals were highly crystalline.

Aptides, a novel class of high-affinity peptides, recognize diverse molecular targets with high affinity and specificity. The solution structure of the aptide APT specifically bound to fibronectin extradomain B (EDB), which represents an unusual protein–protein interaction that involves coupled unfolding and binding, is reported. APT binding is accompanied by unfolding of the C-terminal β strand of EDB, thereby permitting APT to interact with the freshly exposed hydrophobic interior surfaces of EDB. The β-hairpin scaffold of APT drives the interaction by a β-strand displacement mechanism, such that an intramolecular β sheet is replaced by an intermolecular β sheet. The unfolding of EDB perturbs the tight domain association between EDB and FN8 of fibronectin, thus highlighting its potential use as a scaffold that switches between stretched and bent conformations.

The oxygen reduction reaction (ORR) activities of Pt shells were found to have a strong dependence on the surface structure by depositing them on Pd nanocrystals with different shapes.

Droplet-based microreactors are used for the continuous production of Pd nanocrystals. Specifically, commercially available polytetrafluoroethylene (PTFE) tube and silica capillaries are utilized to fabricate a fluidic device capable of generating water-in-oil droplets. In addition to the feasibility of using such droplets as microreactors for conducting a synthesis, the ability to control the composition and concentration of reagents by adjusting the flow rates is demonstrated; reagents are mixed by periodically pinching the PTFE tube, and nanocrystals are produced with uniform size distribution in a continuous fashion. The capability to tailor the size and shape of the resultant nanocrystals is further demonstrated by introducing the reducing agent and capping agent at different flow rates to control the nucleation and growth processes. The ability to transform a bulk synthesis into a droplet-based system holds great potential for the development of a new route to the high-volume production of nanocrystals.

A systematic study on the selective semihydrogenation of alkynes to alkenes on shape-controlled palladium (Pd) nanocrystals was performed. Pd nanocrystals with a cubic shape and thus exposed {100} facets were synthesized in an aqueous solution through the reduction of Na2PdCl4 with L-ascorbic acid in the presence of bromide ions. The Pd nanocubes were tested as catalysts for the semihydrogenation of various alkynes such as 5-decyne, 2-butyne-1,4-diol, and phenylacetylene. For all substrates, the Pd nanocubes exhibited higher alkene selectivity (>90 %) than a commercial Pd/C catalyst (75-90 %), which was attributed to a large adsorption energy of the carbon-carbon triple bond on the {100} facets of the Pd nanocubes. Our approach based on the shape control of Pd nanocrystals offers a simple and effective route to the development of a highly selective catalyst for alkyne semihydrogenation.

We have synthesized sub-10 nm Pd cubic and octahedral nanocrystals and then evaluated their activities towards oxygen reduction reaction (ORR). The ORR activity of Pd nanocubes was one order of magnitude higher than that of Pd octahedra, and comparable to that of the state-of-the-art Pt catalysts.

In order to study the effects of solvent selectivity and temperature on phase behavior and transition of diblock copolymer solution, self-consistent field theory is modified to incorporate the short-range interaction and non-local effects. Inhomogeneous free-energy density is shown to be dependent on solvent selectivity, temperature and copolymer concentration. Enthalpic quantity and entropic contributions are crucial to phase diagrams of diblock copolymer solution. Three selective strengths of solvent-weak, moderate and strong-are chosen for comparison. For a weakly selective solvent, theoretical and experimental results illustrate the same variation tendency in the phase boundary of the order-disorder transition for a symmetric diblock of polystyrene and polyisoprene. Self-consistent field equations can be used to calculate the exact FCC-BCC structural phase transition temperatures in moderately and strongly selective solvents. Detailed comparison with the experimental phase diagrams including lamellar, cylindrical and spherical structures is presented.