The Fe3O4@SiO2 composite nanoparticles were obtained from as-synthesized magnetite (Fe3O4) nanoparticles through the modified St?ber method. Then, the Fe3O4 nanoparticles and Fe3O4@SiO2 composite nanoparticles were ch...The Fe3O4@SiO2 composite nanoparticles were obtained from as-synthesized magnetite (Fe3O4) nanoparticles through the modified St?ber method. Then, the Fe3O4 nanoparticles and Fe3O4@SiO2 composite nanoparticles were characterized by means of X-ray diffraction (XRD), Raman spectra, scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). Recently, the studies focus on how to improve the dispersion of composite particle and achieve good magnetic performance. Hence effects of the volume ratio of tetraethyl orthosilicate (TEOS) and magnetite colloid on the structural, morphological and magnetic properties of the composite nanoparticles were systematically investi-gated. The results revealed that the Fe3O4@SiO2 had better thermal stability and dispersion than the magnetite nanoparticles. Furthermore, the particle size and magnetic property of the Fe3O4@SiO2 composite nanoparticles can be adjusted by changing the volume ratio of TEOS and magnetite colloid.展开更多
One-dimensional and quasi-one-dimensional nanostructure materials are promising building blocks for electromagnetic devices and nanosystems.In this work,the composite Ni0.5Zn0.5Fe2O4（NZFO）/ Pb（Zr0.52Ti0.48）O3（PZT...One-dimensional and quasi-one-dimensional nanostructure materials are promising building blocks for electromagnetic devices and nanosystems.In this work,the composite Ni0.5Zn0.5Fe2O4（NZFO）/ Pb（Zr0.52Ti0.48）O3（PZT） nanofibers with average diameters about 65 nm are prepared by electrospinning from poly（vinyl pyrrolidone） （PVP） and metal salts.The precursor composite NZFO/PZT/PVP nanofibers and the subsequent calcined NZFO/PZT nanofibers are investigated by Fourier transform infrared spectroscopy （FT- IR） ,X-ray diffraction （XRD）,scanning electron microscopy （SEM）.The magnetic properties for nanofibers are measured by vibrating sample magnetometer（VSM）.The NZFO/PZT nanofibers obtained at calcination temperature of 900 °C for 2 h consist of the ferromagnetic spinel NZFO and ferroelectric perovskite PZT phases,which are constructed from about 37 nm NZFO and 17 nm PZT grains.The saturation magnetization of these NZFO/PZT nanofibers increases with increasing calcination temperature and contents of NZFO in the composite.展开更多
The La2O3/Fe2O3-CeO2 composite oxide catalysts were prepared by coprecipitation method, sol-gel method and hydrothermal method. The effect of preparation methods on structure morphology and photocatalytic properties o...The La2O3/Fe2O3-CeO2 composite oxide catalysts were prepared by coprecipitation method, sol-gel method and hydrothermal method. The effect of preparation methods on structure morphology and photocatalytic properties of La2O3/Fe2O3-CeO2 samples was investigated. The results show that the cubic CeO2 structure can be obtained at 600℃. The rod-shaped sample prepared by coprecipitation method, displays the highest crystalline and the strongest diffraction peak intensity. The spherical sample is acquired from sol-gel method, while the small granular sample prepared by hydrothermal method tends to aggregate. The maximum specific surface area of the sample prepared by coprecipitation method is 76.21 m2/g, the minimum specific area of the sample from sol-gel method is 32.66 m2/g and the maximum pore size is 13.84 nm, while the minimum pore volume and pore size of the sample by hydrothermal method are 0.038 cm3/g and 3.95 nm respectively. The band gap energy of catalyst samples is in the following order: sample-CP < sample-SG < sample-HT. The sample obtained by coprecipitation method has the best catalytic degradation performance for methylene blue. Under the excitation of visible light, the degradation rate was 99.58% at 50 minutes, which was higher than those of sol-gel method and hydrothermal method by 5.58% and 9.54% respectively. The catalytic degradation reaction is a first-order kinetic model: ln (c0/ct) = kt + qe. The maximum k-value of the sample degradation process obtained by coprecipitation method is 0.074 min-1.展开更多
Novel magnetic core/shell bimetallic Au/Cu nanoparticles（Fe_3O_4@SiO_2-Au/Cu NPs） were prepared using SiO_2-coated iron oxide（Fe_3O_4@SiO_2） as a supported material. The magnetic Fe_3O_4 colloidal nanocrystal clus...Novel magnetic core/shell bimetallic Au/Cu nanoparticles（Fe_3O_4@SiO_2-Au/Cu NPs） were prepared using SiO_2-coated iron oxide（Fe_3O_4@SiO_2） as a supported material. The magnetic Fe_3O_4 colloidal nanocrystal clusters（CNCs） as nano-core were modified with a silica coating for improvement stability and superficial area of the Au-Cu particles. The morphological structure and chemical composition of the Fe_3O_4@SiO_2-Au/Cu NPs were characterized with high-resolution transmission electron microscopy（HRTEM）, energy-dispersive X-ray（EDX） and X-ray photoelectron spectroscopy（XPS） analyses. The Au and Cu NPs were deposited on the SiO_2 surface in a highly dense and well dispersed manner with an average size of approximately 5 nm. The Fe_3O_4@SiO_2-Au/Cu NPs as magnetic nano-catalysts were applied to the Ullmann coupling reaction of bromamine acid to synthesize 4,40-diamino-1,10-dianthraquinonyl-3,30-disulfonic acid（DAS）. The prepared Fe_3O_4@SiO_2-Au/Cu NPs exhibited efficient catalytic activity with higher conversion and selectivity. A bromamine acid conversion of 97.35% and selectivity for DAS of 88.67% were obtained in aqueous medium. The magnetic nano-catalysts can be readily separated from the reaction system and reused. This new nano-catalytic reaction represents a useful and attractive cleaner production system. The new catalyst system has important and potential applications in dye and pigment industry.展开更多
A Fe modified Na2WO4 compound was synthesized by a solution impregnation method and was ball-milled with MgH2 to constitute a novel MgH2-Fe2O3/Na2WO4 composite. The effects of the Fe2O3/Na2WO4 additive on the hydrogen...A Fe modified Na2WO4 compound was synthesized by a solution impregnation method and was ball-milled with MgH2 to constitute a novel MgH2-Fe2O3/Na2WO4 composite. The effects of the Fe2O3/Na2WO4 additive on the hydrogen storage properties of MgH2 together with the corresponding mechanism were investigated. At 423 K, within the first 200 seconds, the hydrogen absorption amount of MgH2+20 wt% Fe2O3/Na2WO4 was almost 5 times that of pure MgH2. And at 573 K, its total hydrogen desorption amount was 7 times that for pure MgH2. Meanwhile, its onset dehydrogenation temperature was 110 K lower than that of pure MgH2. It was worth noting that the MgH2+20 wt% Fe/Na2WO4 presented the lower dehydrogenation reaction activation energy(Ea) of 35.9 kJ·mol^-1 compared to that of pure MgH2. The active MgWO4, Mg2 FeH6 and MgO formed during the milling process were responsible for the improvement of the hydrogen storage properties for MgH2.展开更多
Enrichment of trace bioactive constituents and metabolites from complex biological samples is challenging.This study presented a one-pot synthesis of magnetic polydopamine nanoparticles(Fe3O4@-SiO2@PDA NPs)with multip...Enrichment of trace bioactive constituents and metabolites from complex biological samples is challenging.This study presented a one-pot synthesis of magnetic polydopamine nanoparticles(Fe3O4@-SiO2@PDA NPs)with multiple recognition sites for the magnetic dispersive solid-phase extraction(MDSPE)of ginsenosides from rat plasma treated with white ginseng.The extracted ginsenosides were characterized by combining an ultra-high-performance liquid chromatography coupled to a highresolution mass spectrometry with supplemental UNIFI libraries.Response surface methodology was statistically used to optimize the extraction procedure of the ginsenosides.The reusability of Fe3O4@-SiO2@PDA NPs was also examined and the results showed that the recovery rate exceeded 80%after recycling 6 times.Furthermore,the proposed method showed greater enrichment efficiency and could rapidly determine and characterize 23 ginsenoside prototypes and metabolites from plasma.In comparison,conventional methanol method can only detect 8 ginsenosides from the same plasma samples.The proposed approach can provide methodological reference for the trace determination and characterization of different bioactive ingredients and metabolites of traditional Chinese medicines and food.展开更多
文摘The Fe3O4@SiO2 composite nanoparticles were obtained from as-synthesized magnetite (Fe3O4) nanoparticles through the modified St?ber method. Then, the Fe3O4 nanoparticles and Fe3O4@SiO2 composite nanoparticles were characterized by means of X-ray diffraction (XRD), Raman spectra, scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). Recently, the studies focus on how to improve the dispersion of composite particle and achieve good magnetic performance. Hence effects of the volume ratio of tetraethyl orthosilicate (TEOS) and magnetite colloid on the structural, morphological and magnetic properties of the composite nanoparticles were systematically investi-gated. The results revealed that the Fe3O4@SiO2 had better thermal stability and dispersion than the magnetite nanoparticles. Furthermore, the particle size and magnetic property of the Fe3O4@SiO2 composite nanoparticles can be adjusted by changing the volume ratio of TEOS and magnetite colloid.
基金Funded by the National Natural Science Foundation of China (No. 50674048)Research Fund for the Doctoral Program of Higher Education of China(No.20103227110006)
文摘One-dimensional and quasi-one-dimensional nanostructure materials are promising building blocks for electromagnetic devices and nanosystems.In this work,the composite Ni0.5Zn0.5Fe2O4（NZFO）/ Pb（Zr0.52Ti0.48）O3（PZT） nanofibers with average diameters about 65 nm are prepared by electrospinning from poly（vinyl pyrrolidone） （PVP） and metal salts.The precursor composite NZFO/PZT/PVP nanofibers and the subsequent calcined NZFO/PZT nanofibers are investigated by Fourier transform infrared spectroscopy （FT- IR） ,X-ray diffraction （XRD）,scanning electron microscopy （SEM）.The magnetic properties for nanofibers are measured by vibrating sample magnetometer（VSM）.The NZFO/PZT nanofibers obtained at calcination temperature of 900 °C for 2 h consist of the ferromagnetic spinel NZFO and ferroelectric perovskite PZT phases,which are constructed from about 37 nm NZFO and 17 nm PZT grains.The saturation magnetization of these NZFO/PZT nanofibers increases with increasing calcination temperature and contents of NZFO in the composite.
文摘The La2O3/Fe2O3-CeO2 composite oxide catalysts were prepared by coprecipitation method, sol-gel method and hydrothermal method. The effect of preparation methods on structure morphology and photocatalytic properties of La2O3/Fe2O3-CeO2 samples was investigated. The results show that the cubic CeO2 structure can be obtained at 600℃. The rod-shaped sample prepared by coprecipitation method, displays the highest crystalline and the strongest diffraction peak intensity. The spherical sample is acquired from sol-gel method, while the small granular sample prepared by hydrothermal method tends to aggregate. The maximum specific surface area of the sample prepared by coprecipitation method is 76.21 m2/g, the minimum specific area of the sample from sol-gel method is 32.66 m2/g and the maximum pore size is 13.84 nm, while the minimum pore volume and pore size of the sample by hydrothermal method are 0.038 cm3/g and 3.95 nm respectively. The band gap energy of catalyst samples is in the following order: sample-CP < sample-SG < sample-HT. The sample obtained by coprecipitation method has the best catalytic degradation performance for methylene blue. Under the excitation of visible light, the degradation rate was 99.58% at 50 minutes, which was higher than those of sol-gel method and hydrothermal method by 5.58% and 9.54% respectively. The catalytic degradation reaction is a first-order kinetic model: ln (c0/ct) = kt + qe. The maximum k-value of the sample degradation process obtained by coprecipitation method is 0.074 min-1.
基金financially supported by the Shanghai Natural Science Foundation (No. 13ZR1400300)National Key R&D Program of China (No. 2017YFB030900)
文摘Novel magnetic core/shell bimetallic Au/Cu nanoparticles（Fe_3O_4@SiO_2-Au/Cu NPs） were prepared using SiO_2-coated iron oxide（Fe_3O_4@SiO_2） as a supported material. The magnetic Fe_3O_4 colloidal nanocrystal clusters（CNCs） as nano-core were modified with a silica coating for improvement stability and superficial area of the Au-Cu particles. The morphological structure and chemical composition of the Fe_3O_4@SiO_2-Au/Cu NPs were characterized with high-resolution transmission electron microscopy（HRTEM）, energy-dispersive X-ray（EDX） and X-ray photoelectron spectroscopy（XPS） analyses. The Au and Cu NPs were deposited on the SiO_2 surface in a highly dense and well dispersed manner with an average size of approximately 5 nm. The Fe_3O_4@SiO_2-Au/Cu NPs as magnetic nano-catalysts were applied to the Ullmann coupling reaction of bromamine acid to synthesize 4,40-diamino-1,10-dianthraquinonyl-3,30-disulfonic acid（DAS）. The prepared Fe_3O_4@SiO_2-Au/Cu NPs exhibited efficient catalytic activity with higher conversion and selectivity. A bromamine acid conversion of 97.35% and selectivity for DAS of 88.67% were obtained in aqueous medium. The magnetic nano-catalysts can be readily separated from the reaction system and reused. This new nano-catalytic reaction represents a useful and attractive cleaner production system. The new catalyst system has important and potential applications in dye and pigment industry.
基金Funded by the National Natural Science Foundation of China(No.51771164)Scientific Research Projects in Colleges and Universities in Hebei Province,China(No.ZD2019307)+2 种基金the Fundamental Research Funds for the Central Universities(No.3142019013)the Natural Science Foundation of Hebei Province of China(No.E2019508214)the Program for Top-notch Young Talents in University of Hebei Province(No.BJ2016043)
文摘A Fe modified Na2WO4 compound was synthesized by a solution impregnation method and was ball-milled with MgH2 to constitute a novel MgH2-Fe2O3/Na2WO4 composite. The effects of the Fe2O3/Na2WO4 additive on the hydrogen storage properties of MgH2 together with the corresponding mechanism were investigated. At 423 K, within the first 200 seconds, the hydrogen absorption amount of MgH2+20 wt% Fe2O3/Na2WO4 was almost 5 times that of pure MgH2. And at 573 K, its total hydrogen desorption amount was 7 times that for pure MgH2. Meanwhile, its onset dehydrogenation temperature was 110 K lower than that of pure MgH2. It was worth noting that the MgH2+20 wt% Fe/Na2WO4 presented the lower dehydrogenation reaction activation energy(Ea) of 35.9 kJ·mol^-1 compared to that of pure MgH2. The active MgWO4, Mg2 FeH6 and MgO formed during the milling process were responsible for the improvement of the hydrogen storage properties for MgH2.
基金This work was supported by grants from the National Natural Science Foundation of China Key Program(NO.81530094)General Program(NO.81573574,81873193)the Science and Technology Development Project of Jilin Province(20190201283JC).
文摘Enrichment of trace bioactive constituents and metabolites from complex biological samples is challenging.This study presented a one-pot synthesis of magnetic polydopamine nanoparticles(Fe3O4@-SiO2@PDA NPs)with multiple recognition sites for the magnetic dispersive solid-phase extraction(MDSPE)of ginsenosides from rat plasma treated with white ginseng.The extracted ginsenosides were characterized by combining an ultra-high-performance liquid chromatography coupled to a highresolution mass spectrometry with supplemental UNIFI libraries.Response surface methodology was statistically used to optimize the extraction procedure of the ginsenosides.The reusability of Fe3O4@-SiO2@PDA NPs was also examined and the results showed that the recovery rate exceeded 80%after recycling 6 times.Furthermore,the proposed method showed greater enrichment efficiency and could rapidly determine and characterize 23 ginsenoside prototypes and metabolites from plasma.In comparison,conventional methanol method can only detect 8 ginsenosides from the same plasma samples.The proposed approach can provide methodological reference for the trace determination and characterization of different bioactive ingredients and metabolites of traditional Chinese medicines and food.
