RuRh Bimetallic Nanoparticles Stabilized by 15-membered Macrocycles-terminated Poly(propylene imine) Dendrimer:Preparation and Catalytic Hydrogenation of Nitrile–Butadiene Rubber

A new fourth-generation poly(propylene imine) dendrimer(G4-M) containing 32 triolefinic 15-membered macrocycles on the surfaces has been synthesized. The bimetallic Ru Rh dendrimer-stabilized nanoparticles(DSNs) were first prepared within G4-M by a co-complexation route. The new G4-M dendrimer has been characterized by 1H nuclear magnetic resonance, infrared radiation, and elemental analysis.The dendrimer-stabilized bimetallic ions and reduction courses were analyzed by UV-vis spectroscopy. Highresolution transmission electron microscopy and energy dispersive spectrometer were used to characterize the bimetallic nanoparticle size, size distribution, and particle morphology. The Ru Rh bimetallic DSNs showed high catalytic activity for the hydrogenation of nitrile-butadiene rubber.

Structural optimization of Au–Pd bimetallic nanoparticles with improved particle swarm optimization method

Due to the dependence of the chemical and physical properties of the bimetallic nanoparticles（NPs） on their structures,a fundamental understanding of their structural characteristics is crucial for their syntheses and wide applications. In this article, a systematical atomic-level investigation of Au–Pd bimetallic NPs is conducted by using the improved particle swarm optimization（IPSO） with quantum correction Sutton–Chen potentials（Q-SC） at different Au/Pd ratios and different sizes. In the IPSO, the simulated annealing is introduced into the classical particle swarm optimization（PSO） to improve the effectiveness and reliability. In addition, the influences of initial structure, particle size and composition on structural stability and structural features are also studied. The simulation results reveal that the initial structures have little effects on the stable structures, but influence the converging rate greatly, and the convergence rate of the mixing initial structure is clearly faster than those of the core-shell and phase structures. We find that the Au–Pd NPs prefer the structures with Au-rich in the outer layers while Pd-rich in the inner ones. Especially, when the Au/Pd ratio is 6：4, the structure of the nanoparticle（NP） presents a standardized Pd（core） Au（shell） structure.

Kinetics of 2,4-dichlorophenol dechlorination by Pd-Fe bimetallic nanoparticles in the presence of humic acid

The remediation of groundwater which contains chlorinated organic compounds (COCs) by nanoscale bimetallic catalysts has received increasing interest in recent years. This report presents the dechlorination of 2,4-dichlorophenol (2,4-DCP) by Pd-Fe bimetallic nanoparticles in the presence of humic acid (HA) to investigate the feasibility of using Pd-Fe for the in situ remediation of contaminated groundwater. Our experimental results indicated that HA had an adverse effect on the dechlorination of 2,4-DCP by Pd-Fe nanoparticles. The rate constant k values of 2,4-DCP dechlorination were 0.017, 0.013, 0.009, 0.006 and 0.004 min?1 for HA concentrations of 0, 5, 10, 15 and 20 mg/L, respectively. The relationship between HA dosage and k values can be described as a linear model.

Synthesis and Enhanced Electrochemical Activity of Ag-Pt Bimetallic Nanoparticles Decorated MWCNTs/PANI Nanocomposites

Ag-Pt bimetallic nanoparticles decorated on MWCNTs/PANI nanocomposites have been synthesized by in-situ chemical oxidative polymerization and chemical co-reduction method. The Fourier transform infrared（FT-IR） spectroscopy, X-ray diffraction（XRD）, ultraviolet-visible（UV-vis） absorption spectroscopy, scanning electron microscopy（SEM） and transmission electron microscopy（TEM） were used to characterize the morphology and structure of the nanocomposites. It can be observed that the PANI was uniformly grown along the MWCNTs to form MWCNsT/PANI fiber-like nanocomposites with diameter about 60 nm, and the Ag-Pt binary nanoparticles were decorated onto MWCNTs/PANI with particle sizes around 6.8 nm. Cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS） were used to characterize the electrochemical performance of the prepared electrode. The results demonstrated that the obtained MWCNTs/PANI/Ag-Pt electrode displayed a good electrochemical activity and fast electron transport, which has potential applications in biosensors and supercapacitors.

Determination of Hydrodynamic Parameters of Chitosan Stabilized Bimetallic Nanoparticles

The hydrodynamic characteristics of bimetallic Ag/Cu and Co/Ag nanopar­ticles stabilized by chitosan were determined.The polydispersity index and the diameter of nanoparticles were observed to decrease in contrast to the original polymer during the creation of chitosan stabilized bimetallic nanoparticles,decreasing from 0.342 to 0.12±0.04 and 2.5 micron to 180 nm,respectively.However,the diffusion coefficient of chitosan was in­creased from 0.2 cm^(2)/s to 2.71 cm2/s during the production of stable bime­tallic nanoparticles.The lack of absorption bands at 500 nm and 700 nm-900 nm in the UV spectra of the samples suggests that in the presence of a reducing agent,copper(II)and cobalt(II)ions undergo full reduction.The relationship between the synthesis conditions and the kind of structure of bimetallic nanoparticles“core-shell”has been discovered.Silver atoms have been shown to be both a core and a shell,depending on the synthesis conditions and chemical nature of metal ions.

Selective suppression of toluene formation in solvent-free benzyl alcohol oxidation using supported Pd-Ni bimetallic nanoparticles

The solvent‐free oxidation of benzyl alcohol was studied using supported Pd‐Ni bimetallic nanoparticles.Compared with monometallic Pd,the addition of Ni to Pd was found to be effective in suppressing the nondesired product toluene,thereby enhancing the selectivity towards benzaldehyde.This result was attributed to a dual effect of Ni addition:the weakening of dissociative adsorption of benzyl alcohol and the promotion of oxygen species involved in the oxidation pathway.

Lewis acid-driven reaction pathways in synergistic cooperative catalysis over gold/palladium bimetallic nanoparticles for hydrogen autotransfer reaction between amide and alcohol

Metal nanoparticle catalysts, especially gold and its bimetallic nanoparticle catalysts, have been widely used in organic transformations as powerful and green catalysts. The concept of employing two distinct catalysts in one reaction system, such as in cooperative and synergistic catalysis, is a powerful strategy in homogeneous catalysis. However, the adaption of such a strategy to metal nanoparticle catalysis is still under development. Recently, we have found that cooperative catalytic systems of gold/palladium bimetallic nanoparticles and Lewis acid can be used for the N‐alkylation of primary amides through hydrogen autotransfer reaction between amide and alcohol. Herein, the results of a detailed investigation into the effects of Lewis acids on this hydrogen autotransfer reac‐tion are reported. It was found that the choice of Lewis acid affected not only the reaction pathway leading to the desired product, but also other reaction pathways that produced several intermedi‐ates and by‐products. Weak Lewis acids, such as alkaline‐earth metal triflates, were found to be optimal for the desired N‐alkylation of amides.

The impact of plasmonic Ag−Au bimetallic nanoparticles on photocurrent enhancement in GaN-based photodetectors

Recently,there has been considerable interest in high-efficiency ultraviolet(UV)photodetectors for their potential practical uses.In this study,a high-quality UV photodetector was fabricated using a combination of Ag and Au NPs with GaN film.The GaN film was deposited using sputtering technique,whereas Ag and Au films were grown using thermal evaporation technique.Ag-Au bimetallic nanoparticles were formed by treating them at the various annealing temperature to improve the interaction between light and the photoactive layers of the photodetectors.The optimal annealing temperature to achieve the best performance of a photodetector is 650℃.This led to a photoresponsivity of 98.5 A/W and the ON/OFF ratio of 705 at low bias voltage of 1 V.This work establishes the foundation for the advancement of high-performance UV photodetectors.

Bimetallic nanoparticles as cascade sensitizing amplifiers for low-dose and robust cancer radio-immunotherapy

Radiotherapy(RT)is one of the most feasible and routinely used therapeutic modalities for treating malignant tumors.In particular,immune responses triggered by RT,known as radio-immunotherapy,can partially inhibit the growth of distantly spreading tumors and recurrent tumors.How-ever,the safety and efficacy of radio-immunotherapy is impeded by the radio-resistance and poor immu-nogenicity of tumor.Herein,we report oxaliplatin(IV)-iron bimetallic nanoparticles(OXA/Fe NPs)as cascade sensitizing amplifiers for low-dose and robust radio-immunotherapy.The OXA/Fe NPs exhibit tumor-specific accumulation and activation of OXA(I)and Fe^(2+)in response to the reductive and acidic microenvironment within tumor cells.The cascade reactions of the released metallic drugs can sensitize RT by inducing DNA damage,increasing ROS and O_(2) levels,and amplifying the immunogenic cell death(ICD)effect after RT to facilitate potent immune activation.As a result,OXA/Fe NPs-based low-dose RT triggered a robust immune response and inhibited the distant and metastatic tumors effectively by a strong abscopal effect.Moreover,a long-term immunological memory effect to protect mice from tumor rechal-lenging is observed.Overall,the bimetallic NPs-based cascade sensitizing amplifier system offers an effi-cient radio-immunotherapy regimen that addresses the key challenges.

Plasmon Induced Heat Funneling from Au to Cu in the Bimetallic Au@Cu Core-Shell Nanoparticles

The bimetallic nanostructures that mix a plasmonic metal with a transition metal in the form of the core-shell nanoparticles are promising to promote catalytic performance.But it is still unclear how the heat(hot electrons and phonons)transfers on the interface between two metals.We have designed and synthesized Au@Cu bimetallic nanoparticles with Au as core and Cu as shell.By using transient absorption spectroscopy,we find that there are two plasmon induced heat funneling processes from Au core to Cu shell.One is the electron temperature equilibrium(electron heat transfer)with equilibration time of~560 fs.The other is the lattice temperature equilibrium(lattice heat transfer)with equilibration time of~13 ps.This plasmon induced heat funneling may be universal in similar bimetallic nanostructures,so our finding could contribute to further understanding the catalytic mechanism of bimetallic plasmonic photothermal catalysis.

Microfluidic-enabled ambient-temperature synthesis of ultrasmall bimetallic nanoparticles

The production of bimetallic nanoparticles with ultrasmall sizes is the constant pursuit in chemistry and materials science because of their promising applications in catalysis,electronics and sensing.Here we report ambient-temperature preparation of bimetallic NPs with tunable size and composition using microfluidic-controlled co-reduction of two metal precursors on silicon surface.Instead of free diffusion of metal ions in bulk system,microfluidic flow could well control the local ions concentration,thus leading to homogenous and controllable reduction rate among different nucleation sites.By controlling precursor concentration,flow rate and reaction time,we rationally design a series of bimetallic NPs including Ag-Cu,Ag-Pd,Cu-Pt,Cu-Pd and Pt-Pd NPs with ultrasmall sizes(~3.0 nm),tight size distributions(relative standard deviation(RSD)<21%),clean surface,and homogenous elemental compositions among particles(standard deviation(SD)of weight ratios<3.5%).This approach provides a facile,green and scalable method toward the synthesis of diverse bimetallic NPs with excellent activity.

Removing polybrominated diphenyl ethers in pure water using Fe/Pd bimetallic nanoparticles

Polybrominated diphenyl ethers （PBDEs） have been widely used as fire-retardants. Due to their high production volume, widespread usage, and environmental persistence, PBDEs have become ubiquitous contaminants in various environments.Nanoscale zero-valent iron （ZVI） is an effective reductant for many halogenated organic compounds. To enhance the degradation efficiency, ZVI/ Palladium bimetallic nanoparticles （nZVI/Pd） were synthe- sized in this study to degrade decabromodiphenyl ether （BDE209） in water. Approximately 90% of BDE209 was rapidly removed by nZVI/Pd within 80 min, whereas about 25% of BDE209 was removed by nZVL Degradation of BDE209 by nZVI/Pd fits pseudo-first-order kinetics. An increase in pH led to sharply decrease the rate of BDE209 degradation. The degradation rate constant in the treatment with initial pH at 9.0 was more than 6.8 x higher than that under pH 5.0. The degradation intermediates of BDE209 by nZVI/Pd were identified and the degradation pathways were hypothesized. Results from this study suggest that nZV//Pd may be an effective tool for treating polybromi- nated diphenyl ethers （PBDEs） in water.

Fabrication of bimetallic nanoparticles modified hollow nanoporous carbons derived from covalent organic framework for efficient degradation of 2,4-dichlorophenol

Bimetallic nanoparticles modified hollow-structured nanoporous carbons(NPCs) have been fabricated via a convenient one-step carbonizing strategy derived from covalent organic framework.The Pd/Fe/NPCs,Pt/Fe/NPCs and Rh/Fe/NPCs were obtained and can be used as Fenton-like catalysts with good stability and reusability.The catalytic activity was evaluated by the degradation of2,4-dichlorophenl(2,4-DCP).These fabricated bimetallic catalysts exhibited much higher catalytic activity than Fe/NPCs at room temperature.The enhancement of catalytic ability was benefited from synergetic catalytic effect of bimetallic nanoparticles and accelerated mass transfer of hollow structure.Additionally,the enhanced catalytic mechanism of bimetallic catalysts was studied in detail and the reasonable reaction pathway was proposed.Besides,the bimetallic catalysts were successfully used for degradation of 2,4-DCP in actual industrial wastewater and the removal efficiency could reach 74.3%within 120 min,which demonstrated the promising potential application of bimetallic catalysts in the removal of pollutants in environment.

Kinetics and Morphological Analysis of Silver Platinum Bimetallic Nanoparticles

Kinetics of a one-pot core-shell synthesis of bimetallic （BM） silver-platinum （Ag-Pt） nanoparticles （NPs） by simultaneous reduction of 1：1 mol fraction of precursors H2PtC16.6H20 and AgNO3 in aqueous solution is reported. Kinetics analysis was done by plotting UV-visible absorptions versus reaction time with a first-order fitting. Recorded constants of Ag NPs （0.079 s^-1）, Ag-Pt NPs 1：1 （0.082 s^-1）, and Pt NPs （0.006 s^-1） were obtained. The NPs suspension solutions were clear, free from AgCl precipitate, and had characteristic optical properties of 450 nm （Ag NPs）, while there were no observable bands for Pt and BM NPs. Morphological analysis using transmission electron microscopy, energy- dispersive X-ray spectroscopy （EDX）, and selected area electron diffraction （SAED） depicted spherical aggregates of Ag NPs, Pt NPs and core shell Pt-Ag NPs 1：1 of average size of 60, 2.5, and 20 mm, respectively. Presence of the Ag and Pt elemental composition in the nanoparticle suspensions was confirmed by EDX. SAED ring patterns revealed a single facecentered cubic crystalline nature of Ag NPs and showed typical Pt-based BMs randomly overlapped ring pattern with sharp diffraction spots.

Characterization and Preparation of Bimetallic Nanoparticles

1 Results Bimetallic particles in the nanometer size range are of substantial interest due to their vast applications in catalysis[1].The synthesis of bimetallic nanoparticles with definite size with a well-control over their nanostructure remains a challenging problem.Thus there exists a great demand for both synthesis and atomic level characterization of nanostructure of bimetallic nanoparticles (NPs).With the recent advent of high-intensity tunable sources of X-rays,now available at synchrotron radia...

Amine facilitates the synthesis of silica-supported ultrasmall bimetallic nanoparticles

Supported catalysts based on metal nanoparticles are a class of widely used heterogeneous catalysts in industry.The catalytic performances of supported metal catalysts are highly determined by many parameters of metal nanoparticles such as their particle size,composition,surface structure and also interfacial interaction with supports[1].

DNA Induced FePt Bimetallic Nanoparticles on Reduced Graphene Oxide for Electrochemical Determination of Dopamine

FePt bimetallic nanoparticles were formed on reduced graphene oxide（rGO） with the help of double-stranded DNA（dsDNA） via a simple and universal route to obtain a FePt/DNA-rGO composite. The FePt nanoparticles with an average size of about 5 nm were well dispersed on rGO. FePt/DNA-rGO modified glassy carbon electrode（GCE） exhibited excellent electrocatalytic activity for the oxidation of dopamine（DA） with a detec- tion limit of 100 nmol/L（S/N = 3）. In addition, the FePt/DNA-rGO based electrochemical sensor showed an excellent selectivity for DA in the presence of ascorbic acid（AA）, uric acid（UA） and other interference reagents. The as-prepared electrochemical biosensor shows great promise in the application of clinical diagnostics.

Interaction between Pd and Cu nanoparticles in bimetallic CuPdx nanoparticles and its impact on oxidation of 1,2-propanediol to aliphatic acids

Bimetallic CuPdx nanoparticles synthesized by the wet chemical reduction method were used as the catalysts in the catalytic oxidation of 1,2-propanediol with gaseous oxygen to aliphatic acids.The palladium and copper nanoparticles in the bimetallic CuP dxnanoparticles had an alloying trend.The catalytic activity of the palladium nanoparticles in the bimetallic CuP dxnanoparticles was enhanced by the interaction between the palladium and copper nanoparticles.When the bimetallic CuPd7 nanoparticles catalyzed the oxidation of 1,2-propanediol in an alkaline aqueous solution at 100℃for 3h,lactic,formic,and acetic acids were dominantly produced with the total selectivity of above 99%at the 1,2-propanediol conversion of 85.9%.The simulation of the reaction kinetic equation on the CuPd7 catalyst showed that the reaction activation energy was 29.4kJ·mol^-1,indicating that the bimetallic CuPd7 nanoparticles had a high catalytic activity in the oxidation reaction between 1,2-propanediol and gaseous oxygen.

Development of Cd-doped Co Nanoparticles Encapsulated in Graphite Shell as Novel Electrode Material for the Capacitive Deionization Technology

Because of the low energy requirement and the environmentally safe byproducts, the capacitive deionization water desalination technology has attracted the attention of many researchers. The important requirements for electrode materials are good electrical conductivity, high surface area, good chemical stability and high specific capacitance. In this study, metallic nanoparticles that are encapsulated in a graphite shell(Cd doped Co/C NPs) are introduced as the new electrode material for the capacitive deionization process because they have higher specific capacitance than the pristine carbonaceous materials. Cd doped Co/C NPs perform better than graphene and the activated carbon. The introduced nanoparticles were synthesized using a simple sol gel technique. A typical sol gel composed of cadmium acetate, cobalt acetate and poly(vinyl alcohol)was prepared based on the polycondensation property of the acetates. The physiochemical characterizations that were used confirmed that the drying, grinding and calcination in an Ar atmosphere of the prepared gel produced the Cd doped Co nanoparticles, which were encapsulated in a thin graphite layer. Overall, the present study suggests a new method to effectively use the encapsulated bimetallic nanostructures in the capacitive deionization technology.

Polymer Film Supported Bimetallic Au–Ag Catalysts for Electrocatalytic Oxidation of Ammonia Borane in Alkaline Media

Ammonia borane is widely used in most areas including fuel cell applications.The present paper describes electrochemical behavior of ammonia borane in alkaline media on the poly(p-aminophenol) film modified with Au and Ag bimetallic nanoparticles.The glassy carbon electrode was firstly covered with polymeric film electrochemically and then,Au,Ag,and Au–Ag nanoparticles were deposited on the polymeric film,respectively.The surface morphology and chemical composition of these electrodes were examined by scanning electron microscopy,transmission electron microscopy,electrochemical impedance spectroscopy,X-ray diffraction,and X-ray photoelectron spectroscopy.It was found that alloyed Au–Ag bimetallic nanoparticles are formed.Electrochemical measurements indicate that the developed electrode modified by Au–Ag bimetallic nanoparticles exhibit the highest electrocatalytic activity for ammonia borane oxidation in alkaline media.The rotating disk electrode voltammetry demonstrates that the developed electrode can catalyze almost six-electron oxidation pathway of ammonia borane.Our results may be attractive for anode materials of ammonia borane fuel cells under alkaline conditions.