Suzuki-Miyaura reactions, involving the activation of carbon-halogen bonds, especially C-C1 bonds, have drawn widespread attention because of their huge industrial potential. However, these reactions are dependent on ...Suzuki-Miyaura reactions, involving the activation of carbon-halogen bonds, especially C-C1 bonds, have drawn widespread attention because of their huge industrial potential. However, these reactions are dependent on the development of highly active and stable catalysts. Herein, we developed a convenient one-pot wet route to synthesize PdxCuy bimetallic nanocrystals for the Suzuki-Miyaura reaction. By introducing Cu, an earth-abundant element, the catalytic activity was greatly enhanced while the amount of Pd required was reduced. PdxCuy nanocrystals of different compositions, including PdBCu, Pd2Cu, PdCu, PdCu2, and PdCu3, were successfully synthesized by tuning the Pd：Cu ratio. Their catalytic performance in Suzuki-Miyaura reactions between phenylboronic acid and halobenzenes （iodo-, bromo-, or chlorobenzene） showed that PdCua nanocatalyst demonstrated the best efficacy.展开更多
As efficient catalysts of electrochemical CO_(2)reduction reaction(CO_(2)RR)towards multicarbon(C_(2+))products,Cu-based catalysts have faced the challenges of increasing the reactive activity and selectivity.Herein,w...As efficient catalysts of electrochemical CO_(2)reduction reaction(CO_(2)RR)towards multicarbon(C_(2+))products,Cu-based catalysts have faced the challenges of increasing the reactive activity and selectivity.Herein,we decorated the surface of Cu nanowires(Cu NWs)with a small amount of Au nanoparticles(Au NPs)by the homo-nucleation method.When the Au to Cu mass ratio is as little as 0.7 to 99.3,the gold-doped copper nanowires(Cu-Au NWs)could effectively improve the selectivity and activity of CO_(2)RR to C_(2+)resultants,with the Faradaic efficiency(FE)from 39.7%(Cu NWs)to 65.3%,the partial current density from 7.0(Cu NWs)to 12.1 mA/cm^(2) under−1.25 V vs.reversible hydrogen electrode(RHE).The enhanced electrocatalytic performance could be attributed to the following three synergetic factors.The addition of Au nanoparticles caused a rougher surface of the catalyst,which allowed for more active sites exposed.Besides,Au sites generated*CO intermediates spilling over into Cu sites with the calculated efficiency of 87.2%,which are necessary for multicarbon production.Meanwhile,the interphase electron transferred from Cu to Au induced the electron-deficient Cu,which favored the adsorption of*CO to further generate multicarbon productions.Our results uncovered the morphology,tandem,electronic effect between Cu NWs and Au NPs facilitated the activity and selectivity of CO_(2)RR to multicarbons.展开更多
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...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.展开更多
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 ...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.展开更多
To coordinate the resonant wavelength of the plasmonic nanoparticles(NPs),the emission band of the reduced graphene oxide(rGO)photodetector at the NIR-region is crucial for the optimal plasmon-enhanced luminescence in...To coordinate the resonant wavelength of the plasmonic nanoparticles(NPs),the emission band of the reduced graphene oxide(rGO)photodetector at the NIR-region is crucial for the optimal plasmon-enhanced luminescence in the device.In contrast to monometallic NPs,where limits the dimensions and extended resonant wavelength,we integrated an Au-Ag bimetallic NPs(BMNPs)to enable resonance tuning at the longer wavelength at the excitation source of 785 nm.These features showed an increase in radiative recombination rates as well as the quantum yield efficiency of the device.The BMNPs were produced from the dewetting process of 600℃and 500℃,both at 1 min after the deposition thickness layer of Au(8 nm)and Ag(10 nm)on the Si substrate using the electron-beam evaporation process.Our BMNPs-rGO photodetector exhibited the responsivity of 2.25 A·W^(–1),Jones of specific detectivity of 2.45×10^(11)Jones,and external quantum efficiency(EQE)of 356%.The rise time and fall time for the photodetector were 32 ns and 186 ns,respectively.This work provided an essential information to enable the versatile plasmon-enhanced application in 2-dimensional(2D)material optoelectronic devices.展开更多
A facile method was used to prepare gold-platinum （Au-Pt） catalysts by direct electrodeposition via cyclic voltammetry in an acidic medium. Various parameters that affect the properties of electrodeposited catalysts...A facile method was used to prepare gold-platinum （Au-Pt） catalysts by direct electrodeposition via cyclic voltammetry in an acidic medium. Various parameters that affect the properties of electrodeposited catalysts were investigated such as initial ap- plied potential, scan rate and deposition time. Initial applied potential plays a more important role in the preparation of bime- tallic nanoparticles （AuPtNPs） since the kinetics of electrodeposition is in competition with the rate of hydrogen evolution. The AuPtNPs electrodeposited on pencil graphite （PG） were used to study the electrooxidation of hydroquinone. Various parame- ters such as pH, scan rate, concentration of hydroquinone and temperature were studied in the electrooxidation process. Ap- parent activation energy （Ea） for the electrooxidation of hydroquinone, calculated from the Arrhenius plot, shows that AuPtNPs catalysts （electrodeposited on the PG） offer less activation energy （ca. 9.500 kJ mo1-1） than the bare PG （ca. 10.345 kJ mol-1）. The AuPtNPs/PG shows better catalytic performance than the PG electrode due to the greater surface area it provides, thus re- sulting in more active sites available for adsorption of hydroquinone molecules on the surface of the catalyst.展开更多
In this work, we demonstrated a simple and efficacious two-step method for the synthesis of Ag@Au core-shell nanoparticles （Ag@AuNPs） and the Ag/Au hollow nanocages （Ag/AuNCs） with Ag nanoparticles （AgNPs） as se...In this work, we demonstrated a simple and efficacious two-step method for the synthesis of Ag@Au core-shell nanoparticles （Ag@AuNPs） and the Ag/Au hollow nanocages （Ag/AuNCs） with Ag nanoparticles （AgNPs） as seeds by adjusting pH, and the preparation of hybrid Ag@AuNPs- or Ag/AuNCs-graphene oxide nanocomposites （Ag@AuNPs-GO or Ag/AuNCs-GO） based on the self-assembly. It was noticed from the elec- trostatic assembly experiment that the loading amount of Ag/AuNCs on GO nanosheet was more than that of Ag@AuNPs. The as-synthesized hybrid materials were characterized by transmission electron microscopy, atomic force microscopy, ξ-potential, high-angle annular dark- field scanning transmission electron microscopy, thermo- gravimetric analyzer and X-ray diffraction. Catalytic activities of Ag@AuNPs, Ag/AuNCs and Ag/AuNCs-GO nanostructures were investigated in the reduction of 4-, 3-or 2-nitrophenol to 4-, 3- or 2-aminophenol, and on the basis of comparative kinetic studies the following trend was obtained for the related catalytic activity： Ag/AuNCs- GO 〉 Ag/AuNCs 〉 Ag@AuNPs. These observations were attributed to the simultaneous effects of surface area available for catalytic reaction and composition of the hybrid nanostructures.展开更多
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 a...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.展开更多
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 var...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.展开更多
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 a...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.展开更多
基金This research was supported in part by the National Natural Science Foundation of China （Nos. 21475007, 21275015 and 21505003）, and the Fundamental Research Funds for the Central Universities （Nos. YS1406, buctrc201507 and buctrc201608）. We also thank the support from the Innovation and Promotion Project of Beijing University of Chemical Technology, the Public Hatching Platform for Recruited Talents of Beijing University of Chemical Technology, the High- Level Faculty Program of Beijing University of Chemical Technology （No. buctrc201325）, and BUCT Fund for Disciplines Construction and Development （No. XK1526）.
文摘Suzuki-Miyaura reactions, involving the activation of carbon-halogen bonds, especially C-C1 bonds, have drawn widespread attention because of their huge industrial potential. However, these reactions are dependent on the development of highly active and stable catalysts. Herein, we developed a convenient one-pot wet route to synthesize PdxCuy bimetallic nanocrystals for the Suzuki-Miyaura reaction. By introducing Cu, an earth-abundant element, the catalytic activity was greatly enhanced while the amount of Pd required was reduced. PdxCuy nanocrystals of different compositions, including PdBCu, Pd2Cu, PdCu, PdCu2, and PdCu3, were successfully synthesized by tuning the Pd：Cu ratio. Their catalytic performance in Suzuki-Miyaura reactions between phenylboronic acid and halobenzenes （iodo-, bromo-, or chlorobenzene） showed that PdCua nanocatalyst demonstrated the best efficacy.
基金the National Key Research and Development Program of China(Nos.2017YFA0700103,2018YFA0704502,and 2021YFA1501500)the National Natural Science Foundation of China(NSFC)(No.22033008)Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(No.2021ZZ103).
文摘As efficient catalysts of electrochemical CO_(2)reduction reaction(CO_(2)RR)towards multicarbon(C_(2+))products,Cu-based catalysts have faced the challenges of increasing the reactive activity and selectivity.Herein,we decorated the surface of Cu nanowires(Cu NWs)with a small amount of Au nanoparticles(Au NPs)by the homo-nucleation method.When the Au to Cu mass ratio is as little as 0.7 to 99.3,the gold-doped copper nanowires(Cu-Au NWs)could effectively improve the selectivity and activity of CO_(2)RR to C_(2+)resultants,with the Faradaic efficiency(FE)from 39.7%(Cu NWs)to 65.3%,the partial current density from 7.0(Cu NWs)to 12.1 mA/cm^(2) under−1.25 V vs.reversible hydrogen electrode(RHE).The enhanced electrocatalytic performance could be attributed to the following three synergetic factors.The addition of Au nanoparticles caused a rougher surface of the catalyst,which allowed for more active sites exposed.Besides,Au sites generated*CO intermediates spilling over into Cu sites with the calculated efficiency of 87.2%,which are necessary for multicarbon production.Meanwhile,the interphase electron transferred from Cu to Au induced the electron-deficient Cu,which favored the adsorption of*CO to further generate multicarbon productions.Our results uncovered the morphology,tandem,electronic effect between Cu NWs and Au NPs facilitated the activity and selectivity of CO_(2)RR to multicarbons.
基金This work is supported by grants from the National Natural Science Foundation of China(Nos.22275081,and 82372117)Guangdong Basic and Applied Basic Research Foundation(2021B1515120065,China)+2 种基金Guangzhou Science and Technology Bureau(202206010068)the Natural Science Foundation of Hebei Province(E2023205004,China)China Postdoctoral Science Foundation(2022M711532 and 2022T150302).
文摘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.
基金supported by the National Key R&D Program of China(2018YFB0604804)the National Natural Science Foundation of China(21603254,21703127,21703276)+1 种基金the Strategic Program of Coal-based Technology of Shanxi Province(MQ2014-11,MQ2014-10)the Key Research Program of the Chinese Academy of Sciences(KFZD-SW-410)
基金financially supported by the National Key R&D Program of China(2020YFA0908900,2018YFA0902600,2022YFB3804700,and 2021YFF1200100)the National Natural Science Foundation of China(22234004)+6 种基金Guangdong Provincial Key Laboratory of Advanced Biomaterials(2022B1212010003)Shenzhen Science and Technology Program(KQTD20190929172743294 and JCYJ20200109141231365)Shenzhen Key Laboratory of Smart Healthcare Engineering(ZDSYS20200811144003009)the Natural Science Foundation of Shenzhen City(JCYJ20190809115005628)Guangdong Innovative and Entrepreneurial Research Team Program(2019ZT08Y191)Guangdong Major Talent Introduction Project(2019CX01Y196)the Tencent Foundation through the XPLORER PRIZE for financial support。
基金financially supported by the National Plan for Science & Technology (NPST), King Saud University Project No. 11-NAN1460-02
文摘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.
基金R.ZAKARIA would like to acknowledge Research University(RU)grant from University Malaya(Grant No.ST048-2021).
文摘To coordinate the resonant wavelength of the plasmonic nanoparticles(NPs),the emission band of the reduced graphene oxide(rGO)photodetector at the NIR-region is crucial for the optimal plasmon-enhanced luminescence in the device.In contrast to monometallic NPs,where limits the dimensions and extended resonant wavelength,we integrated an Au-Ag bimetallic NPs(BMNPs)to enable resonance tuning at the longer wavelength at the excitation source of 785 nm.These features showed an increase in radiative recombination rates as well as the quantum yield efficiency of the device.The BMNPs were produced from the dewetting process of 600℃and 500℃,both at 1 min after the deposition thickness layer of Au(8 nm)and Ag(10 nm)on the Si substrate using the electron-beam evaporation process.Our BMNPs-rGO photodetector exhibited the responsivity of 2.25 A·W^(–1),Jones of specific detectivity of 2.45×10^(11)Jones,and external quantum efficiency(EQE)of 356%.The rise time and fall time for the photodetector were 32 ns and 186 ns,respectively.This work provided an essential information to enable the versatile plasmon-enhanced application in 2-dimensional(2D)material optoelectronic devices.
基金financially supported by a Research University Grant(1001/PKIMIA/811056)financial support from Universiti Sains Malaysia
文摘A facile method was used to prepare gold-platinum （Au-Pt） catalysts by direct electrodeposition via cyclic voltammetry in an acidic medium. Various parameters that affect the properties of electrodeposited catalysts were investigated such as initial ap- plied potential, scan rate and deposition time. Initial applied potential plays a more important role in the preparation of bime- tallic nanoparticles （AuPtNPs） since the kinetics of electrodeposition is in competition with the rate of hydrogen evolution. The AuPtNPs electrodeposited on pencil graphite （PG） were used to study the electrooxidation of hydroquinone. Various parame- ters such as pH, scan rate, concentration of hydroquinone and temperature were studied in the electrooxidation process. Ap- parent activation energy （Ea） for the electrooxidation of hydroquinone, calculated from the Arrhenius plot, shows that AuPtNPs catalysts （electrodeposited on the PG） offer less activation energy （ca. 9.500 kJ mo1-1） than the bare PG （ca. 10.345 kJ mol-1）. The AuPtNPs/PG shows better catalytic performance than the PG electrode due to the greater surface area it provides, thus re- sulting in more active sites available for adsorption of hydroquinone molecules on the surface of the catalyst.
基金Acknowledgments This work was supported by the National Nalural Science Foundation of China （21 105042）, the Science Foundation of China Postdoctor （2014M560572）, the Natural Science Foundation of Shandong Province IZR2015BM024）, and Tai-Shan Scholar Research Fund of Shandong Province. The sludy was partially supported by grant NIH IR01DA037838 to Drs. Li and Nair.
文摘In this work, we demonstrated a simple and efficacious two-step method for the synthesis of Ag@Au core-shell nanoparticles （Ag@AuNPs） and the Ag/Au hollow nanocages （Ag/AuNCs） with Ag nanoparticles （AgNPs） as seeds by adjusting pH, and the preparation of hybrid Ag@AuNPs- or Ag/AuNCs-graphene oxide nanocomposites （Ag@AuNPs-GO or Ag/AuNCs-GO） based on the self-assembly. It was noticed from the elec- trostatic assembly experiment that the loading amount of Ag/AuNCs on GO nanosheet was more than that of Ag@AuNPs. The as-synthesized hybrid materials were characterized by transmission electron microscopy, atomic force microscopy, ξ-potential, high-angle annular dark- field scanning transmission electron microscopy, thermo- gravimetric analyzer and X-ray diffraction. Catalytic activities of Ag@AuNPs, Ag/AuNCs and Ag/AuNCs-GO nanostructures were investigated in the reduction of 4-, 3-or 2-nitrophenol to 4-, 3- or 2-aminophenol, and on the basis of comparative kinetic studies the following trend was obtained for the related catalytic activity： Ag/AuNCs- GO 〉 Ag/AuNCs 〉 Ag@AuNPs. These observations were attributed to the simultaneous effects of surface area available for catalytic reaction and composition of the hybrid nanostructures.
基金support from the National Natural Science Foundation of China(Nos.21825402 and 22074101)the Natural Science Foundation of Jiangsu Province of China(No.BK20191417)111 Project as well as the Collaborative Innovation Center of Suzhou Nano Science and Technology(NANO-CIC).
文摘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.
文摘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.
基金supported by the National Natural Science Foundation of China(Grant Nos.11474234 and 61403318)the Fundamental Research Funds for the Central Universities of China(Grant No.20720160085)
文摘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.
