Pd-based nanocatalyst is a potential oxygen reduction oxidation(ORR)catalyst because of its high activity in alkaline medium and low cost.In this work,bimetallic Pd Au nanocatalysts are prepared by one-pot hydrotherma...Pd-based nanocatalyst is a potential oxygen reduction oxidation(ORR)catalyst because of its high activity in alkaline medium and low cost.In this work,bimetallic Pd Au nanocatalysts are prepared by one-pot hydrothermal method using triblock pluronic copolymers,poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)(PEO19-PPO69-PEO19)(P123)as reducer and stabilizer,and heat-treatment method is applied to regulate catalyst structure and improve catalyst activity.The results show that the heat treatment can agglomerate the catalyst to a certain extent,but effectively improve the crystallinity and alloying degree of the catalyst.The ORR performance of the Pd Au nanocatalysts obtained under different heat treatment conditions is systematically investigated.Compared with commercial Pd black and Pd Au catalyst before heat treatment,the ORR performance of Au Pd nanocatalyst obtained after heat treatment for one hour at 500℃ has been enhanced.The Pd Au nanocatalysts after heat treatment also display enhanced anti-methanol toxicity ability in acidic medium.展开更多
A hydrogen evolution-assisted one-pot aqueous approach was developed for facile synthesis of trimetallic Pd Ni Ru alloy nanochain-like networks（Pd Ni Ru NCNs） by only using KBHas the reductant, without any specific ...A hydrogen evolution-assisted one-pot aqueous approach was developed for facile synthesis of trimetallic Pd Ni Ru alloy nanochain-like networks（Pd Ni Ru NCNs） by only using KBHas the reductant, without any specific additive（e.g. surfactant, polymer, template or seed）. The products were mainly investigated by transmission electron microscopy（TEM）, X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）. The hierarchical architectures were formed by the oriented assembly growth and the diffusioncontrolled deposition in the presence of many in-situ generated hydrogen bubbles. The architectures had the largest electrochemically active surface area（ECSA） of 84.32 mgPdthan Pd Ni nanoparticles(NPs,65.23 mgPd), Pd Ru NPs(23.12 mgPd), Ni Ru NPs（nearly zero）, and commercial Pd black(6.01 mgPd), outperforming the referenced catalysts regarding the catalytic characters for hydrazine oxygen reaction（HOR）. The synthetic route provides new insight into the preparation of other trimetallic nanocatalysts in fuel cells.展开更多
Morphology engineering has been developed as one of the most widely used strategies for improving the performance of electrocatalysts.However,the harsh reaction conditions and cumbersome reaction steps during the nano...Morphology engineering has been developed as one of the most widely used strategies for improving the performance of electrocatalysts.However,the harsh reaction conditions and cumbersome reaction steps during the nanomaterials synthesis still limit their industrial applications.Herein,one-dimensional(1D)novel-segmented PtTe porous nanochains(PNCs)were successfully synthesized by the template methods assisted by Pt autocatalytic reduction.The PtTe PNCs consist of consecutive mesoporous architectures that provide a large electrochemical surface area(ECSA)and abundant active sites to enhance methanol oxidation reaction(MOR).Furthermore,1D nanostructure as a robust sustaining frame can maintain a high mass/charge transfer rate in a long-term durability test.After 2,000 cyclic voltammetry(CV)cycles,the ECSA value of PtTe PNCs remained as high as 44.47 m^(2)·gPt^(-1),which was much larger than that of commercial Pt/C(3.95 m^(2)·gPt^(-1)).The high catalytic activity and durability of PtTe PNCs are also supported by CO stripping test and density functional theory calculation.This autocatalytic reduction-assisted synthesis provides new insights for designing efficient low-dimensional nanocatalysts.展开更多
Magnetic assembly at the nanoscale level brings potential possibilities in obtaining novel delicate nanostructures with unique physical, photonic or electronic properties. Interface surfactant micelle-directed assembl...Magnetic assembly at the nanoscale level brings potential possibilities in obtaining novel delicate nanostructures with unique physical, photonic or electronic properties. Interface surfactant micelle-directed assembly strategy holds great promising in fabricating ordered mesoporous materials with multifunctionality and pore parameter tunability. Combing these, herein, one-dimensional (1D) nanochains with well-aligned silica-coated magnetic particles as core and mesoporous aluminosilicate as shell are rational fabricated for the first time through magnetic field induced interface coassembly in biliquid system followed by the incorporation of Al species via in-situ chemical modification and transformation strategy. The obtained magnetic mesoporous aluminosilicate nanochains (MMAS-NCs) possess well-defined core-shell-shell sandwich nanostructure, tunable perpendicular mesopore channels in the shell (2.7–7.6 nm), high surface area (359 m^(2)·g^(-1)), abundant acidic sites, and superparamagnetism with a magnetization saturation of 13.8 emu·g^(-1). Thanks to the unique properties, the MMAS-NCs exhibit excellent performance in acting as magnetically recyclable superior solid acid catalysts and nanostirrers with high conversion of over 96.8%, selectivity of 95.0% in the deprotection reaction of benzaldehyde dimethylacetal to benzaldehyde. Moreover, MMAS-NCs exhibit an interesting pore size effect on the catalytic activity, namely, in the pore size range of 2–8 nm, the catalysts with larger pores show significantly enhanced catalytic activity due to the balanced mass transport and density of surface active sites.展开更多
Faster response benefits the high-performance of magnetic material in various live applications.Hence,enhancing response speed toward the applied field via engineering advantages in structures is highly desired.In thi...Faster response benefits the high-performance of magnetic material in various live applications.Hence,enhancing response speed toward the applied field via engineering advantages in structures is highly desired.In this paper,the precise synthesis of Co nanochain with the tunable length-diameter ratio is realized via a magnetic-field-guided assembly approach.The Co nanochain exhibits enhanced microwave absorption performance(near to-60 dB,layer thickness 2.2 mm)and broader effective absorption bandwidth(over 2/3 of total S,C,X,Ku bands).Furthermore,the simulated dynamic magnetic response reveals that the domain motion in 1D chain is faster than that in 0D nanoparticle,which is the determining factor of magnetic loss upgrade.Meanwhile,based on the controllable magnetic field experiment via in situ transmission electron microscopy,the association between magnetic response and microstructure is first present at the nanometer-level.The real and imaginary parts of relative complex permeability are determined by the domain migration confined inside Co nanochain and the magnetic flux field surrounded outside Co nanochain,respectively.Importantly,these findings can be extended to the novel design of microwave absorbers and promising candidates of magnetic carriers based on 1D structure.展开更多
基金Financial supports from the National Natural Science Foundation of China (21503120, 21403126)Hubei Provincial Natural Science Foundation of China (2018CFB659)Innovation Foundation from China Three Gorges University (2019SSPY150)
文摘Pd-based nanocatalyst is a potential oxygen reduction oxidation(ORR)catalyst because of its high activity in alkaline medium and low cost.In this work,bimetallic Pd Au nanocatalysts are prepared by one-pot hydrothermal method using triblock pluronic copolymers,poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)(PEO19-PPO69-PEO19)(P123)as reducer and stabilizer,and heat-treatment method is applied to regulate catalyst structure and improve catalyst activity.The results show that the heat treatment can agglomerate the catalyst to a certain extent,but effectively improve the crystallinity and alloying degree of the catalyst.The ORR performance of the Pd Au nanocatalysts obtained under different heat treatment conditions is systematically investigated.Compared with commercial Pd black and Pd Au catalyst before heat treatment,the ORR performance of Au Pd nanocatalyst obtained after heat treatment for one hour at 500℃ has been enhanced.The Pd Au nanocatalysts after heat treatment also display enhanced anti-methanol toxicity ability in acidic medium.
基金financially supported by the Nation Natural Science Foundation of China(No.21475118)
文摘A hydrogen evolution-assisted one-pot aqueous approach was developed for facile synthesis of trimetallic Pd Ni Ru alloy nanochain-like networks（Pd Ni Ru NCNs） by only using KBHas the reductant, without any specific additive（e.g. surfactant, polymer, template or seed）. The products were mainly investigated by transmission electron microscopy（TEM）, X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）. The hierarchical architectures were formed by the oriented assembly growth and the diffusioncontrolled deposition in the presence of many in-situ generated hydrogen bubbles. The architectures had the largest electrochemically active surface area（ECSA） of 84.32 mgPdthan Pd Ni nanoparticles(NPs,65.23 mgPd), Pd Ru NPs(23.12 mgPd), Ni Ru NPs（nearly zero）, and commercial Pd black(6.01 mgPd), outperforming the referenced catalysts regarding the catalytic characters for hydrazine oxygen reaction（HOR）. The synthetic route provides new insight into the preparation of other trimetallic nanocatalysts in fuel cells.
基金This work was supported by the National Natural Science Foundation of China(Nos.52171051,52130103,52271237,52271163,51971026,12034002,and 11904025)the Natural Science Foundation of Henan province(No.222300420086).We thank Dr.Song Hong from the Electron Microscopy Laboratory at Beijing University of Chemical Technology for the help with the aberration-corrected transmission electron microscope.
文摘Morphology engineering has been developed as one of the most widely used strategies for improving the performance of electrocatalysts.However,the harsh reaction conditions and cumbersome reaction steps during the nanomaterials synthesis still limit their industrial applications.Herein,one-dimensional(1D)novel-segmented PtTe porous nanochains(PNCs)were successfully synthesized by the template methods assisted by Pt autocatalytic reduction.The PtTe PNCs consist of consecutive mesoporous architectures that provide a large electrochemical surface area(ECSA)and abundant active sites to enhance methanol oxidation reaction(MOR).Furthermore,1D nanostructure as a robust sustaining frame can maintain a high mass/charge transfer rate in a long-term durability test.After 2,000 cyclic voltammetry(CV)cycles,the ECSA value of PtTe PNCs remained as high as 44.47 m^(2)·gPt^(-1),which was much larger than that of commercial Pt/C(3.95 m^(2)·gPt^(-1)).The high catalytic activity and durability of PtTe PNCs are also supported by CO stripping test and density functional theory calculation.This autocatalytic reduction-assisted synthesis provides new insights for designing efficient low-dimensional nanocatalysts.
基金This work was supported by the National Natural Science Foundation of China(Nos.21701153,21875044,52073064,22005058,and 22005057)the National Key R&D Program of China(No.2020YFB2008600)+4 种基金Program of Shanghai Academic Research Leader(No.19XD1420300)the State Key Laboratory of Transducer Technology of China(No.SKT1904)China Postdoctoral Science Foundation(Nos.2020M670973 and BX20200085)Sichuan Science and Technology Program(No.2020YJ0243)The authors extend their appreciation to the International Scientific Partnership Program ISPP at King Saud University for funding this research work through ISPP-17-94(2).
文摘Magnetic assembly at the nanoscale level brings potential possibilities in obtaining novel delicate nanostructures with unique physical, photonic or electronic properties. Interface surfactant micelle-directed assembly strategy holds great promising in fabricating ordered mesoporous materials with multifunctionality and pore parameter tunability. Combing these, herein, one-dimensional (1D) nanochains with well-aligned silica-coated magnetic particles as core and mesoporous aluminosilicate as shell are rational fabricated for the first time through magnetic field induced interface coassembly in biliquid system followed by the incorporation of Al species via in-situ chemical modification and transformation strategy. The obtained magnetic mesoporous aluminosilicate nanochains (MMAS-NCs) possess well-defined core-shell-shell sandwich nanostructure, tunable perpendicular mesopore channels in the shell (2.7–7.6 nm), high surface area (359 m^(2)·g^(-1)), abundant acidic sites, and superparamagnetism with a magnetization saturation of 13.8 emu·g^(-1). Thanks to the unique properties, the MMAS-NCs exhibit excellent performance in acting as magnetically recyclable superior solid acid catalysts and nanostirrers with high conversion of over 96.8%, selectivity of 95.0% in the deprotection reaction of benzaldehyde dimethylacetal to benzaldehyde. Moreover, MMAS-NCs exhibit an interesting pore size effect on the catalytic activity, namely, in the pore size range of 2–8 nm, the catalysts with larger pores show significantly enhanced catalytic activity due to the balanced mass transport and density of surface active sites.
基金supported by the Ministry of Science and Technology of China(973 Project)(No.2018YFA0209102)the National Natural Science Foundation of China(Nos.11727807,51725101,51672050,and 61790581).
文摘Faster response benefits the high-performance of magnetic material in various live applications.Hence,enhancing response speed toward the applied field via engineering advantages in structures is highly desired.In this paper,the precise synthesis of Co nanochain with the tunable length-diameter ratio is realized via a magnetic-field-guided assembly approach.The Co nanochain exhibits enhanced microwave absorption performance(near to-60 dB,layer thickness 2.2 mm)and broader effective absorption bandwidth(over 2/3 of total S,C,X,Ku bands).Furthermore,the simulated dynamic magnetic response reveals that the domain motion in 1D chain is faster than that in 0D nanoparticle,which is the determining factor of magnetic loss upgrade.Meanwhile,based on the controllable magnetic field experiment via in situ transmission electron microscopy,the association between magnetic response and microstructure is first present at the nanometer-level.The real and imaginary parts of relative complex permeability are determined by the domain migration confined inside Co nanochain and the magnetic flux field surrounded outside Co nanochain,respectively.Importantly,these findings can be extended to the novel design of microwave absorbers and promising candidates of magnetic carriers based on 1D structure.
