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A uniform Cs-promoted Ni/Al2O3 nanocatalyst prepared by using a reliable automatic system shows extremely high productivity as well as good stability and coke resistance. The improved stability with doped Cs was elucidated by computational studies.

Copper oxide nanoparticles (CuO NPs) with a clean surface supported on carbon nanofibers (CNFs) in one-pot were prepared by simple solid-state grinding and aging followed by thermal treatment, yielding CuO nanoparticles with high (23.8 wt%) and uniform CuO loading in the absence of surfactants and solvent. The CuO NPs on CNFs (CuO/CNF) showed excellent catalytic activity in transforming a wide variety of alkynes into alkenyl boronates using B

In this paper, we describe a facile new synthetic method for making highly dispersed molybdenum disulfide nanoparticles (~ 3 nm) on Ketjenblack carbon (MoS2/KC) via particle incorporation and sequential sulfidation. The MoS2/KC nanocatalyst obtained showed a good onset potential value (0.83 V), high durability, and excellent methanol tolerance for the oxygen reduction reaction. We report a simple method for making highly dispersed molybdenum disulfide nanoparticles (~ 3 nm) on Ketjenblack carbon support for sustainable oxygen reduction reactions with good onset potential, high durability, and excellent methanol tolerance.

Bimetallic Rh–Co nanoparticles supported on nitrogen-doped porous carbon (Rh–Co/NPC) were synthesized from metal precursors and urea through a simple thermal decomposition/reduction under a nitrogen flow. The Rh–Co/NPC nanocatalyst which contains highly dispersed alloy nanoparticles (∼6 nm) showed high catalytic performance as well as good recyclability for the C–Se coupling reaction of diphenyl diselenide and aryl boronic acid and p-nitrophenol reduction.

Efficient catalysts for energy conversation from wastewater and energy storage are still existing. The effective hydrogen energy production through lower energy consumption is considered as a promi...

Synthetic methods of mesoporous silica using surfactants or ionic liquids as a template have several disadvantages to commercialization such as low economic feasibility and low sustainability. Thus...

Catalytic reduction by the reverse water gas shift (RWGS) reaction is an efficient way to utilize carbon dioxide and reduce its environmental impact as a greenhouse gas. In this research, an active CuFe/Al 2 O 3 nano powder was developed as a high temperature reforming catalyst for the RWGS reaction. The powder was synthesized by a wet-impregnation method and the copper alloy was uniformly dispersed on the γ-Al 2 O 3 support. At a gas space velocity of 60,000 h −1 , the conversion of carbon dioxide was 42% at 700 °C, which is very close to the equilibrium conversion of 44%. The results indicated excellent reforming activity of the CuFe/Al 2 O 3 catalyst for the high temperature RWGS reaction. In addition, the catalyst was applied in the form of a reforming layer over a conventional Ni-based electrode of a solid oxide electrolysis cell (SOEC) for an integrated SOEC-RWGS system. Hydrogen produced from steam electrolysis over the Ni-based cathode can be efficiently utilized to reduce the carbon dioxide by the RWGS reaction over the CuFe/Al 2 O 3 -based reforming layer. In this bilayer design, the reforming layer maintained the high surface area necessary for achieving good reforming activity, while the electrode layer possessed a high degree of sintering to enhance its electrochemical function. A high conversion of carbon dioxide (37% at 700 °C) was obtained in our bilayer SOEC-RWGS system. This promising result suggests the feasibility of the integrated SOEC-RWGS system for an efficient co-electrolysis device.

Hollow nanomaterials have attracted great interest because of their many applications in catalysis, nanoreactors, drug delivery systems, for lubrication and in gas sensors. Here, carbon sphere templates were prepared from glucose under hydrothermal conditions to facilitate the synthesis of hollow Fe2O3 nanospheres. Thermal decomposition of an iron precursor in benzylalcohol with the carbon spheres resulted in the deposition of Fe3O4 nanoparticles on the carbon sphere templates. The nanoparticles on the carbon surface naturally agglomerate and form a dense oxide shell during the calcination step, which produces typical Fe2O3 hollow structures. The gas sensing performance of the hollow Fe2O3 nanospheres was investigated at an operating temperature of 300 °C. The hollow Fe2O3 nanospheres showed high sensitivity (R = 10.766 at 1 ppm formaldehyde) with a linear response to formaldehyde gas concentration in the range of 0.8~2.4 ppm, and good selectivity to formaldehyde gas in volatile organic compounds, compared to commercial Fe2O3 nanoparticles.

A hierarchical architecture designated as Fe5C2@Ns-rGO/CNT, consisting of carbon nanotubes, steam activated N-doped reduced graphene oxides, and activated iron carbide nanoparticles, was prepared via microwave irradiation and subsequent CO activation. The Fe5C2@Ns-rGO/CNT was successfully applied to a rapid CO hydrogenation reaction showing extremely high activity of 4.4 × 10−3 molCO gFe−1 s−1 at a fast gas velocity of 210 NL gcat−1 h−1.

Mesoporous SiO2-supported Cu2O nanoparticles as an egg-shell type catalyst were prepared by impregnation method. The obtained Cu2O/SiO2 egg-shell nanocatalyst had a large surface area and narrow pore size distribution. In addition, most of the Cu2O nanoparticles, with sizes around 2.0 nm, were highly dispersed in the mesoporous silica. Accordingly, fast reactant diffusion to the active sites would occur, especially when the active metal sites are selectively located on the outer part of the support, i.e., the outer region of the egg shell. In solvent-free Sonogashira reactions for the synthesis of ynones from acyl chlorides and terminal alkynes, this catalyst exhibited a very high catalytic activity. The excellent catalytic performance can be attributed to the synergistic advantages of mesoporous structure and monodispersed Cu2O nanoparticles.

The production of shape-controlled heterometallic nanoparticles (NPs) consisting of Pt and nonprecious metal oxides is crucial to demonstrate the composition–property relationship of NPs. Herein, we report a facile one-pot approach for the controlled synthesis of dumbbell-like Pt–Fe3O4–MnOx and dendritic Pt–MnOx NPs. The key to the success of this synthesis is in changing the quantity of Fe(CO)5 additive to control the reaction kinetics. In the absence of Fe(CO)5, dendritic Pt–MnOx NPs were synthesized through the assembly of small seed NPs. On the other hand, dumbbell-like Pt–Fe3O4–MnOx NPs were obtained in the presence of Fe(CO)5 through controlling the nucleation and growth of Fe and Mn on the Pt NPs, followed by air oxidation. Compared to a Pt/graphene oxide (GO) catalyst, dumbbell-like Pt–Fe3O4–MnOx NPs on GO showed an enhancement of specific activity toward the oxygen reduction reaction owing to the compressive-strain effect exerted on the Pt lattice.

Nickel-based catalysts have been applied to the catalytic reactions for transfer hydrogenation of carbonyl compounds. In the present work, highly dispersed nickel particles located at the pores of mesoporous silica spheres (Ni@mSiO2) were prepared via an optimized melt infiltration route. The nickel nanoparticles of 10 wt% in the Ni@mSiO2 catalyst could be uniformly loaded with high dispersion of 36.3%, resulting excellent performance for catalytic transfer hydrogenation of aryl ketones.

Large-scale synthesis of cobalt nanoparticles supported on alumina (Co/Al2O3), which has well dispersed metallic cobalt around 15 nm, was conducted via a simple melt infiltration process of a cobalt hydrate salt and subsequent thermal reduction. The catalytic performance of Co/Al2O3 was studied for Fischer–Tropsch synthesis in order to optimize the liquid fuel productivity for target hydrocarbon products controlled by reaction pressures and temperatures. The catalyst showed promising CO conversions up to 76% with high hydrocarbon productivity (∼1.0 gHC gcat−1 h−1) and good stability.

The high-temperature Fischer–Tropsch synthesis reaction has been exploited to selectively produce lower-olefins and gasoline-range hydrocarbons (C5–C12) from a mixture of carbon monoxide and hydrogen, using iron-based catalysts. For this reaction, improving the selectivity and stability of the catalyst has been a major challenge, as has enhancing the activity. In the present work, we introduce iron-carbide nanoparticles supported on a porous gamma-alumina framework as a robust catalyst, prepared via a simple melt infiltration process and subsequent thermal treatment, for high-temperature Fischer–Tropsch synthesis. The iron-carbide/alumina catalyst showed much better catalytic performance, with a higher stability for producing gasoline-range hydrocarbon products, than did iron-carbide/mesoporous silica (SBA-15) and iron-carbide/activated carbon (AC).

A one-pot synthesis of rose-like Pd–Fe 3 O 4 nanocomposites via the controlled thermal decomposition of Fe(CO) 5 and reduction of Pd(OAc) 2 is reported. This rose-like Pd–Fe 3 O 4 composite structure has a high surface area owing to the individual Pd–Fe 3 O 4 nanosheets, which imparted a high catalytic activity for Sonogashira coupling reactions. Moreover, the catalyst also demonstrated magnetic recyclability.

Nanocrystalline iron ore particles were fabricated by a wet-milling process using an Ultra Apex Mill, after which they were used as raw materials of iron-based catalysts for low-temperature Fischer-Tropsch synthesis (FTS) below 280 degrees C, which usually requires catalysts with a high surface area, a large pore volume, and a small crystallite size. The wet-milling process using the Ultra Apex Mill effectively destroyed the initial crystallite structure of the natural iron ores of several tens to hundreds of nanometers in size, resulting in the generation of nanocrystalline iron ore particles with a high surface area and a large pore volume. The iron-ore-based catalysts prepared from the nanocrystalline iron ore particles effectively catalyzed the low-temperature FTS, displaying a high CO conversion (about 90%) and good C5+ hydrocarbon productivity (about 0.22 g/g(cat)(-h)). This demonstrates the feasibility of using the iron-ore-based catalysts as inexpensive and disposable catalysts for the low-temperature FTS.

Temperature-programmed reduction using H2 (H2-TPR) and CO (CO-TPR) was carried out to investigate the reduction and carburization behavior of nanocrystalline ferrihydrite-based Fe/Cu/K/SiO2 catalysts for use in Fischer-Tropsch synthesis (FTS). Unlike pure ferrihydrite, the ferrihydrite-based catalysts did not pass through the intermediate decomposition step of ferrihydrite (Fe9O2(OH)23) into hematite (a-Fe2O3) as they were reduced into magnetite (Fe3O4). This is attributed to the enhanced thermal stability induced by SiO2. For the ferrihydrite-based catalysts, the reduction of ferrihydrite into magnetite occurred in two stages because the reduction promoter, Cu, is not homogeneously distributed on the catalyst surfaces. The Cu-rich sites are likely to be reduced in the first stage, and the Cu-lean sites may be reduced in the second stage. After the ferrihydrite is reduced to magnetite, the reduction process of magnetite was similar to that for conventional hematite-based FTS catalysts: 'magnetite --> metallic iron' and 'magnetite --> wustite (FeO) or fayalite (Fe2SiO4) --> metallic iron' in the H2 atmosphere; 'magnetite --> iron carbides' in the CO atmosphere.

A facile synthetic strategy for a hybrid Cu2O/Pd–Fe3O4 nanocomposite via controlled thermal decomposition of Fe(CO)5 and reduction of Pd(OAc)2 and Cu(acac)2 was developed. The Pd precursor and amount of reducing agent used during the synthetic process controlled the morphology of the Cu2O/Pd–Fe3O4 nanocomposites. The prepared Cu2O/Pd–Fe3O4 nanocomposites showed excellent catalytic performance for C–H arylation, which can be attributed to the synergetic catalytic system formed from the catalytically effective Pd and Cu2O. Moreover, to the best of our knowledge, the C–H arylation of 4-nitroimidazoles with aryl iodides catalyzed by heterogeneous nanocatalysts has not been reported in the literature.

We prepared highly productive Co/MCF nanocatalysts by a facile melt infiltration process using a hydrated Co precursor. The highly loaded Co particles (30 wt%) were uniformly dispersed in the large pores (30 nm) of the MCF support. The Co particles had an average diameter of 17 nm and clean surfaces without any surfactant. The Co/MCF catalyst exhibited very high hydrocarbon productivity (∼0.98 gtotal HC gcat−1 h−1) with high activity (CO conversion = 77%, CTY = 7.6 × 10−5 molCO gCo−1 s−1) and good selectivity for C5+ long chain hydrocarbons (∼81%) in Fischer–Tropsch synthesis.

The development of an eco-friendly and economical synthetic pathway of nanomaterials such as metal nanoparticles and nanoporous metals remains a challenging topic in the field of nanomaterials. Here we report a novel and eco-friendly series of synthetic methods from the preparation of metal nanoparticles to the fabrication of hierarchical porous metals by using partial film boiling phenomena established by a reactor with the inverse configuration of conventional Leidenfrost drop reactors, which is much more favorable to large-scale production than conventional Leidenfrost drop reactors. As a result, we have revealed two important facts, which can offer fresh vision to the field of metal nanoparticle and nanoporous metal synthesis. The first one is that Pd and Pt precursor can be reduced to neutral Pd and Pt nanoparticles under basic condition established by partial film boiling phenomena without reducing agents such as ethanol and citric acid. The second one is that when citric acid and ethanol as a mild ...

Combined high catalytic activity and thermal stability were achieved with a well-structured, surfactant-free Pd@porous SiO2 yolk–shell nanostructure, resulting from the entirely exposed Pd core particles and highly porous silica shells. Pd@SiO2 core–shell nanoparticles were synthesized by a water-in-oil microemulsion method for direct silica coating of as-prepared tiny Pd nanoparticles. Hydrothermal etching and subsequent high thermal treatment generated large pores in the silica shells and facilitated complete removal of surfactants around the core particles. The surfactant-free Pd@pSiO2 yolk–shell nanoparticles efficiently catalyzed the oxidation of benzyl alcohol as well as that of various substituted benzyl alcohols.

Cs promoted Fe5C2/charcoal nanocatalysts bearing small iron carbide particles of 8.5 and 14 nm were prepared through a simple melt-infiltration process and a wetness impregnation method; the resulting materials showed very high CO conversion (>95%) and good selectivity, especially at Cs/Fe = 0.025, resulting in a high liquid oil productivity (∼0.4 gliq gcat−1 h−1) in high-temperature Fischer–Tropsch synthesis.

We developed a photocatalyst (T–FC) that incorporated anatase TiO2 (T) nanoparticles on magnetically enhanced carbon [iron oxide (F; α,γ-Fe2O3–Fe3O4) supported on activated carbon (C)] for use as a highly visible-light-active, low-cost, recyclable, and photostable catalyst for the degradation of organic dyes and bacterial sterilization. The T–FC photocatalyst with a large Brunauer–Emmett–Teller surface area (564.3 m2 g−1) was synthesized by wet-chemical processing and ultrasound irradiation. Under visible-light irradiation, the highest photocatalytic activity for T–FC ([k] = 3.874 h−1) was 32.6 and 3.1 times higher than those of T ([k] = 0.119 h−1) and FC ([k] = 1.259 h−1). The recyclability of T–FC was high, with a dye decolorization rate measured at ∼95.8% of the initial value after 15 recycles. Furthermore, T–FC showed more substantial antimicrobial properties against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) than T and FC when exposed to visible-light for 120 min. Even after 10 cycles of use, T–FC killed more than 95.7% of E. coli. These results indicated that T–FC might have utility in several promising applications such as wastewater treatment and as a bactericidal agent.

This paper reviews recent developments in the field of hybrid Pd nanoparticles and their catalytic activity in the Suzuki coupling reaction, which is used extensively in the fabrication of both simple and complex biaryl compounds. We developed three types of Pd-silica hybrid nanoparticles. Pd/SiO2 nanobeads containing tiny Pd clusters, Pd@nickel phyllosilicate yolk-shell nanoparticles, Pd@porous SiO2 yolk-shell nanoparticles were synthesized, and they displayed highly efficient catalytic activity and excellent reusability. The hybrid nanoparticles also catalyzed the Suzuki coupling reaction with various substrates, including bromobenzene and chlorobenzene. This review also briefly discusses the synthesis procedure, structural characterization, and catalytic activity of hybrid Pd nanoparticles.

In the present work, we synthesized magnetically separable Pd/Fe3O4/charcoal nanocatalysts by simple solid-state grinding of a mixture of salts and the simultaneous thermal decomposition of the salts. The highly loaded Pd nanoparticles (20 wt%) were well dispersed in the porous charcoal, with an average diameter of ∼5 nm and clean surfaces without any surfactant. Moreover, the simultaneously obtained Fe3O4 nanoparticles (10 wt%) had good superparamagnetic character, enabling quick separation of the catalyst from the products and re-dispersion in the reaction solution. The bifunctional catalyst showed a high product time yield with various substituted aryl halides and aryl boronic acids.

Fischer–Tropsch synthesis was carried out over industrially important Fe/Cu/K/SiO2 catalysts containing a small amount of residual sodium which originated from the sodium carbonate solution used as a precipitating agent. The structural promoter, SiO2, was incorporated by two comparative sequences: immediately after precipitation (AP) or after a subsequent wash (AW). Whereas AW exhibited severe deactivation during the reaction, AP displayed high and stable catalytic activity for the entire reaction time. Furthermore, AP showed higher selectivity of liquid hydrocarbons, in particular heavy hydrocarbons, than AW. We attribute the advantageous catalytic performance observed in AP to the enhanced reducibility and higher surface basicity of AP, potentially induced by higher dispersion of catalysts and promoters.

Recently, a convenient melt-infiltration method, using a hydrated metal salt with porous support, was developed to prepare various metal/metal-oxide nanocatalysts. Until now, millimeter-scale, bead-shaped, cobalt egg-shell catalysts have been used to enhance the rate of reactant diffusion and catalyst performance. In the present work, new SiO2@Co/mSiO2 egg-shell nanoreactors (~300 nm) were synthesized with controlled Co content of 10 and 20 wt%. This was accomplished using a selective melt-infiltration process with porous silica shells around solid-silica cores. The SiO2@Co(10 wt%)/mSiO2 egg-shell catalyst that bears small cobalt nanoparticles of -2 nm was successfully employed for the industrially valuable Fischer-Tropsch synthesis reaction, showing the high activity of -8.0 x 10(-5) mol(CO) x gCo(-1) x S(-1).

Fischer-Tropsch synthesis (FTS) was carried out over nanocrystalline ferrihydrite-based (Fe9O2(OH)23) catalysts activated by different reducing agents: syngas (H2+CO), CO, and H2. The syngas activation successfully changed the ferrihydrite-based catalysts into an active and stable catalytic structure with chi-carbide (Fe2.5 C) and epsilon'-carbide (Fe2.2 C). The crystal structure of the catalysts obtained by syngas activation was similar to the structure obtained by CO activation; this similarity was probably due to the peculiar reduction behavior of the ferrihydrite-based catalysts, which exhibit much greater reducibility in CO atmosphere than in H2 atmosphere. The performance of the catalysts activated by syngas was much higher than the performance of the catalysts activated by H2 and was comparable to the performance of the catalysts activated by CO. This strongly demonstrates that the ferrihydrite-based catalysts are advantageous for industrial FTS processes because syngas can be commonly used for both activation pre-treatment and subsequent reaction.

In a trayed bubble column, the structure of the partitioning plate plays an important role on the bubble behavior. This study examined the effect of the opening ratio and pore size of the plate on the bubble break-up frequency and bubble size distribution. The sieve tray was used as the partitioning plate. The opening ratio was closely related to gas cap development. The stagnation of bubble flow and a gas cap were observed with an opening ratio less than 48.5%. The gas cap increased with decreasing opening ratio and increasing superficial gas velocity. The main effect of the sieve tray could be categorized into the additional drag force and bubble break-up depending on the sieve pore size. When the sieve pore size was smaller than the Sauter diameter of the bubble swarm, the movement of rising bubbles was interrupted by the drag force applied by the surrounding mesh lines. On the other hand, when the sieve pore size was larger than the Sauter diameter, the bubbles were affected by the additional bubble break-up. After the bubbles penetrated the sieve tray, the bubble size distribution shifted to a smaller one and the Sauter diameter decreased.

Pd/SiO2 nanobeads containing tiny Pd clusters with a diameter of about 2 nm were prepared via a sol–gel process for SiO2 by using a water-in-oil microemulsion with Pd complexes and subsequent hydrogen reduction by heat treatment. The Pd/SiO2 nanostructures were employed in Suzuki coupling reactions with various substrates, and they served as good catalysts in these reactions.

Fischer–Tropsch synthesis was carried out over precipitated iron-based catalysts with different amounts of CO2 in the feed stream while maintaining both total reaction pressure (1.5 MPa) and partial pressure of H2 + CO (0.75 MPa) using an inert balance gas, N2. The CO2 in the feed stream decreased the rate of hydrocarbon formation, but it had no significant influence on the carbon number distribution of hydrocarbons. The CO2 in the feed stream also suppressed CO2 formation, decreasing both CO conversion and CO2 selectivity. We attribute the decreased reaction rate to the partial competition in the adsorption behavior between CO and CO2 as revealed in the temperature-programmed desorption.

CuO hollow nanospheres on acetylene black (CuO/AB) have been used for the catalytic [3 + 2] cycloaddition of azides with terminal alkynes without solvent, and within 1 min under microwave irradiation. The CuO/AB was readily separated by centrifugation, and could be reused five times under the present reaction conditions without any loss of catalytic activity.

Nickel-based catalysts have been good candidates for steam reforming of methane, but their stability has been restricted due to the agglomeration among particles at high temperature. In the present work, a new type of Ni@SiO2 yolk-shell nanoreactor framework comprising Ni cores inside hollow silica shells has been prepared through direct silica coating and subsequent selective etching of the metal cores. This nanoreactor framework is remarkably stable at high temperatures up to 973 K, because the silica hollow shells around the nickel cores essentially block particle sintering. The Ni@SiO2 nanoreactor structure is employed as a model catalyst for the steam methane reforming reaction. The catalysts exhibit a continuous conversion rate of methane and hydrogen, and significantly enhanced stability at high temperatures, leading to high recyclability without loss of catalytic activity. These reaction properties are superior to Ni/MCF catalysts, and comparable with state-of-the-art commercial catalysts. This catalyst design can be generalized for other bifunctional systems, such as Co@SiO2 and Fe@SiO2.

Nanoreactor frameworks have many advantages over bulk catalyst structures in terms of providing a regular reaction environment and conformational stability. In this work, Au@SiO2 nanoreactor frameworks were chemically modified to improve the catalytic efficiency of o-nitroaniline reduction. The porosity of silica shells was readily controlled by introducing C18TMS as a porogen with heat treatment. The diffusion rate of the silica layers was tuned from 5.9 × 10−19 to 2.1 × 10−18 m2 s−1, which directly altered the turnover frequency and rate constant of the reaction. Carboxylate functionality was introduced on the gold cores of Au@SiO2 nanoreactors by 3-MPA addition. The reaction rate was enhanced by a maximum of 2.4 times compared to unfunctionalized catalysts through a strong interaction between carboxylate anions and o-nitroaniline. Totally, the rate constant of Au@SiO2 yolk−shell nanoreactors exhibits a 13-fold enhancement by diffusion and surface functionality control. These results indicate that the r...

We report the shape and size control of polyhedral gold nanocrystals by a modified polyol process. The rapid reduction of gold precursors in refluxing 1,5-pentanediol has successfully provided a series of gold nanocrystals in the shape of octahedra, truncated octahedra, cuboctahedra, cubes, and higher polygons by incremental changes of silver nitrate concentration. All nanocrystals were obtained quantitatively and were uniform in shape and size in the range of approximately 100 nm. Smaller octahedra and cubes were also prepared by using large amounts of PVP. Silver species generated from AgNO3 seemed to determine the final nanocrystal morphology by the selective growth of {111} and/or the restriction of {100}. The shape evolution of the particles was addressed by quenching the reactions at different time intervals. The approximately 60 nm seeds were generated rapidly and grown slowly with simultaneous edge sharpening. Aging the reaction mixture focused the size and shape of the nanocrystals by Ostwald ripening. We believe that our selective growth conditions can be applied to other shapes and compositions of face-centered cubic metals.

Polycrystalline Mo/MoOx nanoflakes were synthesized via the thermal decomposition of molybdenum carbonyl in the presence of stabilizing surfactants. These nanoflakes were readily transformed into single-crystalline MoO3 and MoS2 nanoparticles within 2 nm diameters by in situ addition of oxygen and sulfur into the colloidal solution.

A various size of Sn-Cu nanoparticles were synthesized by using a modified polyol process for low temperature electronic devices. Monodispersive Sn-Cu nanoparticles with diameters of 21 nm, 18 nm and 14 nm were synthesized. In addition, the eutectic composition shift was also observed in nano-sized particles as compared with bulk alloys. By controlling the size and eutectic composition, a significant melting temperature depression of 30.3 degrees C was achieved. These melting temperature depression approaches will reduce adverse thermal effects in electronic devices and provide the synthesis guidelines for bimetallic nanoparticles with a low melting temperature.

An approach for gram-scale synthesis of uniform Cu2O nanocubes by a one-pot polyol process was used. The CuO hollow nanostructures were prepared by adding aqueous ammonia solutions with Cu2O nanocube colloidal solutions. CuO hollow nanospheres on acetylene black (CuO/AB), were synthesized and used for the catalytic [3 + 2] cycloaddition of azides with terminal alkynes to provide products in good yields with high regioselectivity. The CuO/AB was readily separated by centrifugation and could be reused ten times under the present reaction conditions without any loss of catalytic activity. Transition metals loaded onto acetylene black are useful reagents for a wide variety of organic transformations. Moreover, these heterogeneous systems are promising industrial catalysts.

CuO hollow nanostructures have been used for the catalytic [3 + 2] cycloaddition of azides with terminal alkynes to provide the products in good yields with high regioselectivity.

Metal nanoparticles whose sizes are between those of bulk and monomeric metal species have a wide range of applications; such nanoparticles are used in various electronic, optical, and magnetic devices as well as in the production of catalytic ma-terials. Transition-metal nanoparticles are an important class of catalysts used in organic synthesis.

ZnO-CuO core-branch hybrid nanoparticles, synthesized by copper oxide growth and controlled oxidation on ZnO nanospheres, exhibited remarkable enhancement of catalytic activity and stability for ultrasound-assisted [3+2] azide-alkyne cycloaddition reactions, due to their high surface area and active facets of the CuO branches.

Ni@SiO(2) core-shell nanoparticles were transformed to Ni particles on silica spheres via a branched nickel phyllosilicate phase by hydrothermal and hydrogen reduction reactions; the final morphology was successfully employed as an active nanocatalyst for the hydrogen transfer reaction of acetophenone.