Bimetallic gold-silver core-shell nanoparticles were prepared by chemical reduction in aqueous solution, following a method that was friendly to the environment, allowing us to use this for medicinal purposes. Gold na...Bimetallic gold-silver core-shell nanoparticles were prepared by chemical reduction in aqueous solution, following a method that was friendly to the environment, allowing us to use this for medicinal purposes. Gold nanoparticles were synthesized, and silver cations were then reduced on the nanoparticles. Using the optical properties of metallic nanoparticles, surface plasmon resonance was determined by UV-Vis spectroscopy, and the values obtained for gold and silver were approximately 520 nm and 400 nm in wavelength, respectively. The absorption peaks of the surface plasmon band show a clear red-shift due to size effect in the case of the silver surface, and a plasmon coupling effect, in the case of gold. To obtain a better understanding of the coating conditions, high resolution transmission electron microscopy was used. The average hydrodynamic size and the size distribution of the synthesized nanoparticles were obtained by dynamic light scattering. The development of this process, which is benign for the environment, opens the possibility for many applications in the areas of renewable energy, medicine and biology.展开更多
A simple electrochemical method for the in situ preparation of homogeneously dispersed gold-polyaniline core/shell nanocomposite particles with controlled size on the highly oriented pyrolytic graphite(HOPG)was demons...A simple electrochemical method for the in situ preparation of homogeneously dispersed gold-polyaniline core/shell nanocomposite particles with controlled size on the highly oriented pyrolytic graphite(HOPG)was demonstrated.The HOPG surface was modified preferentially by covalent bonding of a two-dimensional 4-aminophenyl monolayer employing diazonium chemistry.AuCl4 -ions were attached to the Ar-NH2 termination and reduced electrochemically.This results in the formation of Au nuclei that could be further grown into gold nanoparticles.The formation of polyaniline as the shell wrap of Au nanoparticle was established by localized electro-polymerization.These core-shell nanocomposites prepared were characterized by AFM and cyclic voltammetry.The results show that the gold-polyaniline core-shell composites on HOPG have a mean particle size of 100 nm in diameter and the polyaniline shell thickness is about 15 nm.展开更多
Using organic aqua regia,a recently discovered powerful organic leaching agent,an effective process of recovering Pt directly from Pt-Au bimetallic nanoparticles was demonstrated.The purities of the Pt recovered from ...Using organic aqua regia,a recently discovered powerful organic leaching agent,an effective process of recovering Pt directly from Pt-Au bimetallic nanoparticles was demonstrated.The purities of the Pt recovered from a mixture of Au and Pt nanoparticles and from Pt-Au core-shell nanoparticle catalyst are as high as (99.49±0.22)%,and (95.02±0.08)%,respectively.The novel recovery process promises applications in catalysis industry.展开更多
MXene is a new type of layered two-dimensional transition metal carbide materials differing from graphene, demonstrating intriguing chemical/physical properties. Here the chemical modification of MXene and next fabric...MXene is a new type of layered two-dimensional transition metal carbide materials differing from graphene, demonstrating intriguing chemical/physical properties. Here the chemical modification of MXene and next fabrication of core-shell MXene-COOH@(PEI/PAA)_n composites have been investigated. The obtained MXene-based composites were treated with gold nanoparticles to form MXene—COOH@(PEI/PAA)_n@AuNPs nanocomposites, and their catalytic properties for nitro-compounds were studied. The prepared nanocomposites demonstrated good catalytic activity and reproducibility, showing potential applications in composite catalysts and environmental fields.展开更多
Deposition of platinum(Pt)monolayers(PtML)on Au substrate represents a robust strategy to maximally utilize the Pt atoms and meanwhile achieve high catalytic activity towards methanol oxidation reaction for direct met...Deposition of platinum(Pt)monolayers(PtML)on Au substrate represents a robust strategy to maximally utilize the Pt atoms and meanwhile achieve high catalytic activity towards methanol oxidation reaction for direct methanol fuel cells owing to a substrate-induced tensile strain effect.However,recent studies showed that Pt(ML)on Au substrate are far from perfect smooth monoatomic layer,but actually exhibited three-dimensional nanoclusters.Moreover,the Pt(ML)suffered from severe structural instability and thus activity degradation during long-term electrocatalysis.To regulate the growth of Pt(ML)Au surface and also to improve its structural stability,we exploit dealloyed AuCu core-shell nanoparticles as a new substrate for depositing Pt(ML).By using high-resolution scanning transmission electron microscopy and energy dispersive X-ray elemental mapping combined with electrochemical characte rizations,we reveal that the dealloyed AuCu core-shell nanoparticles can effectively promote the deposition of Pt(ML)closer to a smooth monolayer structure,thus leading to a higher utilization efficiency of Pt and higher intrinsic activity towards methanol oxidation compared to those on pure Au nanoparticles.Moreover,the Pt(ML)deposited on the AuCu core-shell NPs showed substa ntially enhanced stability compared to those on pure Au NPs during long-term electrocatalysis over several hours,during which segregation of Cu to the Au/Pt interface was revealed and suggested to play an important role in stabilizing the Pt(ML)catalysts.展开更多
Synthesis of gold nanoparticles(AuNPs) and Pluronic triblock copolymer composite in aqueous medium was studied.Gold-polymer nanocomposite with different structures was fabricated by tailoring the molar ratio of gold p...Synthesis of gold nanoparticles(AuNPs) and Pluronic triblock copolymer composite in aqueous medium was studied.Gold-polymer nanocomposite with different structures was fabricated by tailoring the molar ratio of gold precursors to Pluronic P123 molecules or pH value of the P123 solution.When a lower volume ratio of [AuCl4-]/[P123](0.05) was employed at pH 11.1,a nanostructure similar to plum pudding was obtained.AuNPs with an average diameter of 13.1 nm were embedded in Pluronic assemblies,and each one held about 21 single gold nanoparticles.When [AuCl4-]/[P123] was increased to 0.1,core-shell structure was obtained if the pH value was in the range of 10.6～11.6,while gold polyhedra were fabricated when pH value was 8.1.Typical core-shell AuNPs had an average diameter of 9.6 nm with a narrow size distribution,while gold polyhedras with a mean diameter of 12.8 nm was obtained.The specific morphologies of the resultant nanocomposite were presumably obtained due to the synergistic interaction among the reactants.展开更多
To design efficient and low-cost core-shell electrocatalysts with an ultrathin platinum shell, the balance between platinum dosage and durability in acid solution is of great importance. In the present work, trimetall...To design efficient and low-cost core-shell electrocatalysts with an ultrathin platinum shell, the balance between platinum dosage and durability in acid solution is of great importance. In the present work, trimetallic Au@PdPt core-shell nanoparticles(NPs)with Pd/Pt molar ratios ranging from 0.31:1 to 4.20:1 were synthesized based on the Au catalytic reduction strategy and the subsequent metallic replacement reaction. When the Pd/Pt molar ratio is 1.19:1(designated as Au@Pd_(1.19) Pt_1 NPs), the superior electrochemical activity and stability were achieved for oxygen reduction reaction(ORR) in acid solution. Especially, the specific and mass activities of Au@Pd_(1.19) Pt_1 NPs are 1.31 and 6.09 times higher than those of commercial Pt/C catalyst. In addition, the Au@Pd_(1.19) Pt_1 NPs presented a good durability in acid solution. After 3000 potential cycles between 0.1 and 0.7 V(vs. Ag/AgCl), the oxygen reduction activity is almost unchanged. This study provides a simple strategy to synthesize highperformance trimetallic ORR electrocatalyst for fuel cells.展开更多
This paper reports an effective method for the synthesis of platinum nanostructures with anisotropic morphologies by decomposition of platinum dichloride in oleylamine at intermediate temperatures catalyzed by gold se...This paper reports an effective method for the synthesis of platinum nanostructures with anisotropic morphologies by decomposition of platinum dichloride in oleylamine at intermediate temperatures catalyzed by gold seed nanoparticles.A small quantity of spherical gold nanoparticles formed in situ was used to trigger the nucleation and anisotropic growth of the Pt nanocrystals.By varying the amount of gold seed nanoparticles,porous fl ower-like,irregular polyhedron-shaped,multi-branched rod shaped,and caterpillar-like Pt nanostructures were produced in high yields at 190240°C in reaction times of a few minutes.Control of morphology under different conditions has been systematically studied and a kinetically controlled induced growth mechanism has been proposed.展开更多
A method of in-situ reduction to prepare Au@Pt core-satellite nanopar- ticles （NPs） is described by using Au NPs coating poly[1-methyl 3-（2-methacryloyloxy propylimidazolium bromine）] （PMMPImB-@-Au NPs） as the t...A method of in-situ reduction to prepare Au@Pt core-satellite nanopar- ticles （NPs） is described by using Au NPs coating poly[1-methyl 3-（2-methacryloyloxy propylimidazolium bromine）] （PMMPImB-@-Au NPs） as the template. After electrostatic complex chloroplatinic acid with PMMPImB shell, the composite NP was directly reduced with N2H4 to produce Au@Pt core-satellite NPs. The characterization of composite and core-satellite NPs under different amounts of chloroplatinic acid were studied by DLS, UV-vis absorption spectrum and TEM. The satellite Pt NPs with a small size （-2 nm） dotted around Au core, and the resulting Au@Pt core-satellite NPs showed a red-shift surface plasmon resonance （SPR） and a good dispersion due to effectively electrostatic repulsion providing by the polymeric ionic liquid （PIL） shell. Finally, Au@Pt core-satellite NPs exhibit an enhanced catalytic activity and cycled catalytic capability for the reduction ofp- nitrophenol with NaBH4.展开更多
文摘Bimetallic gold-silver core-shell nanoparticles were prepared by chemical reduction in aqueous solution, following a method that was friendly to the environment, allowing us to use this for medicinal purposes. Gold nanoparticles were synthesized, and silver cations were then reduced on the nanoparticles. Using the optical properties of metallic nanoparticles, surface plasmon resonance was determined by UV-Vis spectroscopy, and the values obtained for gold and silver were approximately 520 nm and 400 nm in wavelength, respectively. The absorption peaks of the surface plasmon band show a clear red-shift due to size effect in the case of the silver surface, and a plasmon coupling effect, in the case of gold. To obtain a better understanding of the coating conditions, high resolution transmission electron microscopy was used. The average hydrodynamic size and the size distribution of the synthesized nanoparticles were obtained by dynamic light scattering. The development of this process, which is benign for the environment, opens the possibility for many applications in the areas of renewable energy, medicine and biology.
基金Project(50721003)supported by the Creative Research Group of National Natural Science Foundation of ChinaProject(50825102)supported by the National Science Fund for Distinguished Young Scholars,China
文摘A simple electrochemical method for the in situ preparation of homogeneously dispersed gold-polyaniline core/shell nanocomposite particles with controlled size on the highly oriented pyrolytic graphite(HOPG)was demonstrated.The HOPG surface was modified preferentially by covalent bonding of a two-dimensional 4-aminophenyl monolayer employing diazonium chemistry.AuCl4 -ions were attached to the Ar-NH2 termination and reduced electrochemically.This results in the formation of Au nuclei that could be further grown into gold nanoparticles.The formation of polyaniline as the shell wrap of Au nanoparticle was established by localized electro-polymerization.These core-shell nanocomposites prepared were characterized by AFM and cyclic voltammetry.The results show that the gold-polyaniline core-shell composites on HOPG have a mean particle size of 100 nm in diameter and the polyaniline shell thickness is about 15 nm.
文摘Using organic aqua regia,a recently discovered powerful organic leaching agent,an effective process of recovering Pt directly from Pt-Au bimetallic nanoparticles was demonstrated.The purities of the Pt recovered from a mixture of Au and Pt nanoparticles and from Pt-Au core-shell nanoparticle catalyst are as high as (99.49±0.22)%,and (95.02±0.08)%,respectively.The novel recovery process promises applications in catalysis industry.
基金financially supported by the National Natural Science Foundation of China (Nos.21473153 and 51771162)Support Program for the Top Young Talents of Hebei Province,China Postdoctoral Science Foundation (No.2015M580214)+1 种基金the Scientific and Technological Research and Development Program of Qinhuangdao City (No.201701B004)Undergraduate Training Programs for Innovation and Entrepreneurship of Yanshan University (No.CXXL2017227)
文摘MXene is a new type of layered two-dimensional transition metal carbide materials differing from graphene, demonstrating intriguing chemical/physical properties. Here the chemical modification of MXene and next fabrication of core-shell MXene-COOH@(PEI/PAA)_n composites have been investigated. The obtained MXene-based composites were treated with gold nanoparticles to form MXene—COOH@(PEI/PAA)_n@AuNPs nanocomposites, and their catalytic properties for nitro-compounds were studied. The prepared nanocomposites demonstrated good catalytic activity and reproducibility, showing potential applications in composite catalysts and environmental fields.
基金financial supports by National Natural Science Foundation of China(NSFC,Nos.21573123,51622103)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01N111)+1 种基金Guangdong Natural Science Foundation for Distinguished Young Scholars(No.2016A030306035)Basic Research Program of Shenzhen(No.JCYJ20160531194754308)in China。
文摘Deposition of platinum(Pt)monolayers(PtML)on Au substrate represents a robust strategy to maximally utilize the Pt atoms and meanwhile achieve high catalytic activity towards methanol oxidation reaction for direct methanol fuel cells owing to a substrate-induced tensile strain effect.However,recent studies showed that Pt(ML)on Au substrate are far from perfect smooth monoatomic layer,but actually exhibited three-dimensional nanoclusters.Moreover,the Pt(ML)suffered from severe structural instability and thus activity degradation during long-term electrocatalysis.To regulate the growth of Pt(ML)Au surface and also to improve its structural stability,we exploit dealloyed AuCu core-shell nanoparticles as a new substrate for depositing Pt(ML).By using high-resolution scanning transmission electron microscopy and energy dispersive X-ray elemental mapping combined with electrochemical characte rizations,we reveal that the dealloyed AuCu core-shell nanoparticles can effectively promote the deposition of Pt(ML)closer to a smooth monolayer structure,thus leading to a higher utilization efficiency of Pt and higher intrinsic activity towards methanol oxidation compared to those on pure Au nanoparticles.Moreover,the Pt(ML)deposited on the AuCu core-shell NPs showed substa ntially enhanced stability compared to those on pure Au NPs during long-term electrocatalysis over several hours,during which segregation of Cu to the Au/Pt interface was revealed and suggested to play an important role in stabilizing the Pt(ML)catalysts.
文摘Synthesis of gold nanoparticles(AuNPs) and Pluronic triblock copolymer composite in aqueous medium was studied.Gold-polymer nanocomposite with different structures was fabricated by tailoring the molar ratio of gold precursors to Pluronic P123 molecules or pH value of the P123 solution.When a lower volume ratio of [AuCl4-]/[P123](0.05) was employed at pH 11.1,a nanostructure similar to plum pudding was obtained.AuNPs with an average diameter of 13.1 nm were embedded in Pluronic assemblies,and each one held about 21 single gold nanoparticles.When [AuCl4-]/[P123] was increased to 0.1,core-shell structure was obtained if the pH value was in the range of 10.6～11.6,while gold polyhedra were fabricated when pH value was 8.1.Typical core-shell AuNPs had an average diameter of 9.6 nm with a narrow size distribution,while gold polyhedras with a mean diameter of 12.8 nm was obtained.The specific morphologies of the resultant nanocomposite were presumably obtained due to the synergistic interaction among the reactants.
基金supported by the National Natural Science Foundation of China (21773224, 21633008, 21575134, 11374297, 21405149)the National Key Research and Development Plan (2016YFA0203200)K. C. Wong Education Foundation
文摘To design efficient and low-cost core-shell electrocatalysts with an ultrathin platinum shell, the balance between platinum dosage and durability in acid solution is of great importance. In the present work, trimetallic Au@PdPt core-shell nanoparticles(NPs)with Pd/Pt molar ratios ranging from 0.31:1 to 4.20:1 were synthesized based on the Au catalytic reduction strategy and the subsequent metallic replacement reaction. When the Pd/Pt molar ratio is 1.19:1(designated as Au@Pd_(1.19) Pt_1 NPs), the superior electrochemical activity and stability were achieved for oxygen reduction reaction(ORR) in acid solution. Especially, the specific and mass activities of Au@Pd_(1.19) Pt_1 NPs are 1.31 and 6.09 times higher than those of commercial Pt/C catalyst. In addition, the Au@Pd_(1.19) Pt_1 NPs presented a good durability in acid solution. After 3000 potential cycles between 0.1 and 0.7 V(vs. Ag/AgCl), the oxygen reduction activity is almost unchanged. This study provides a simple strategy to synthesize highperformance trimetallic ORR electrocatalyst for fuel cells.
基金the National Natural Science Foundation of China(Nos.20501005,20771037)the Program for New Century Excellent Talents in Universities of China(NCET-06-0417)+1 种基金Pujiang Talents Project(07pj14032),Shuguang Project(06SG33)SRFDP(20070251014)for fi nancial support.
文摘This paper reports an effective method for the synthesis of platinum nanostructures with anisotropic morphologies by decomposition of platinum dichloride in oleylamine at intermediate temperatures catalyzed by gold seed nanoparticles.A small quantity of spherical gold nanoparticles formed in situ was used to trigger the nucleation and anisotropic growth of the Pt nanocrystals.By varying the amount of gold seed nanoparticles,porous fl ower-like,irregular polyhedron-shaped,multi-branched rod shaped,and caterpillar-like Pt nanostructures were produced in high yields at 190240°C in reaction times of a few minutes.Control of morphology under different conditions has been systematically studied and a kinetically controlled induced growth mechanism has been proposed.
基金We acknowledge the financial support from the National Natural Science Foundation of China （Grant Nos. 51103035 and 51403055）.
文摘A method of in-situ reduction to prepare Au@Pt core-satellite nanopar- ticles （NPs） is described by using Au NPs coating poly[1-methyl 3-（2-methacryloyloxy propylimidazolium bromine）] （PMMPImB-@-Au NPs） as the template. After electrostatic complex chloroplatinic acid with PMMPImB shell, the composite NP was directly reduced with N2H4 to produce Au@Pt core-satellite NPs. The characterization of composite and core-satellite NPs under different amounts of chloroplatinic acid were studied by DLS, UV-vis absorption spectrum and TEM. The satellite Pt NPs with a small size （-2 nm） dotted around Au core, and the resulting Au@Pt core-satellite NPs showed a red-shift surface plasmon resonance （SPR） and a good dispersion due to effectively electrostatic repulsion providing by the polymeric ionic liquid （PIL） shell. Finally, Au@Pt core-satellite NPs exhibit an enhanced catalytic activity and cycled catalytic capability for the reduction ofp- nitrophenol with NaBH4.
