It is a great advantage to design advanced materials with outstanding porosity and controllable band gab. In this study, （Fe, Ti）-containing mesoporous silica （x Fe/Ti-HMS） nanoparticles were prepared by a photo-a...It is a great advantage to design advanced materials with outstanding porosity and controllable band gab. In this study, （Fe, Ti）-containing mesoporous silica （x Fe/Ti-HMS） nanoparticles were prepared by a photo-assisted deposition PAD technique, where x is a nominal composition ofFe （l to 4 wt%））. The prepared samples were characterized by DR-UV, XRD, and TEM techniques. The results showed the insertion of Fe into intra-framework of Ti-HMS resulted in a gradual narrowing of the band gap of Ti-HMS samples with increment of Fe wt%. TEM observations reveal that Fe nanoparticles are evenly distributed within Ti-HSM matrix at different Fe wt%. Such results indicate the possibility to control the band gap of a single-site photocatalyst （Ti-HMS） by coupling it with the conventional nano-sized Fe catalysts.展开更多
A controlled cross-linking polymerization containing intra- and intermolecular reactions was designed based on random coil morphology of macromolecules in solution. The soluble intramolecular cross-linked maeromolecu...A controlled cross-linking polymerization containing intra- and intermolecular reactions was designed based on random coil morphology of macromolecules in solution. The soluble intramolecular cross-linked maeromolecule （ICM） was successfully synthesized in the system with PVA and MDI. We found an especial dissolving phenomenon, namely the semi-soluble phenomenon when some gels dissolved in DMF. The chain growth process of ICMs was investigated by Transmission electron microscopy （TEM） pictures of samples at different reacting times, in addition, TEM pictures show ICMs have three kinds of styles in structure, viz. ＂globule structure＂, ＂nubby structure＂ and the intervenient between the above two structures, and the efflux time of the ICMs was measured by an Ubbelohde viscosimeter, it was found that the efflux time decreases with the degree ofcrosslink increasing.展开更多
Arnphiphilic cyclodextrin-calixarene conjugates 1 and 2 were synthesized from "click claemxstry, and tnelr sen-asscmuly uchaviors were investigated by transmission electron microscopy, and atomic force microscopy...Arnphiphilic cyclodextrin-calixarene conjugates 1 and 2 were synthesized from "click claemxstry, and tnelr sen-asscmuly uchaviors were investigated by transmission electron microscopy, and atomic force microscopy. The results obtained show that 1 and 2 can self-assemble to form distinctly different aggregations, and the morphology of aggregations critically relies on the polarity and hydrophilicity of the solvent.展开更多
Manganese selenide （MnSe） possesses unique magnetic properties as an important magnetic semiconductor, but the synthesis and properties of MnSe nanocrystals are less developed compared to other semiconductor nanocry...Manganese selenide （MnSe） possesses unique magnetic properties as an important magnetic semiconductor, but the synthesis and properties of MnSe nanocrystals are less developed compared to other semiconductor nanocrystals because of the inability to obtain high-quality MnSe, especially in the metastable wurtzite structure. Here, we have successfully fabricated wurtzite MnSe nanocrystals via a colloidal approach which affords uniform crystal sizes and tailored shapes. The selective binding strength of the amine surfactant is the determining factor in shape-control and shape-evolution. Bullet-shapes could be transformed into shuttle-shapes if part of the oleylamine in the reaction solution was replaced by trioctylamine, and tetrapod-shaped nanocrystals could be formed in trioctylamine systems. The three-dimensional （3D） structure of the bullet-shaped nanorods has been demonstrated by the advanced transmission electron microscope （TEM） 3D-tomography technology. High-resolution TEM （HRTEM） and electron energy-loss spectroscopy （EELS） show that planar-defect structures such as stacking faults and twinning along the [001] direction arise during the growth of bullet-shapes. On the basis of careful HRTEM observations, we propose a ＂quadra-twin core＂ growth mechanism for the formation of wurtzite MnSe nanotetrapods. Furthermore, the wurtzite MnSe nanocrystals show low- temperature surface spin-glass behavior due to their noncompensated surface spins and the blocking temperatures increase from 8.4 K to 18.5 K with increasing surface area/volume ratio of the nanocrystals. Our results provide a systematic study of wurtzite MnSe nanocrystals.展开更多
文摘It is a great advantage to design advanced materials with outstanding porosity and controllable band gab. In this study, （Fe, Ti）-containing mesoporous silica （x Fe/Ti-HMS） nanoparticles were prepared by a photo-assisted deposition PAD technique, where x is a nominal composition ofFe （l to 4 wt%））. The prepared samples were characterized by DR-UV, XRD, and TEM techniques. The results showed the insertion of Fe into intra-framework of Ti-HMS resulted in a gradual narrowing of the band gap of Ti-HMS samples with increment of Fe wt%. TEM observations reveal that Fe nanoparticles are evenly distributed within Ti-HSM matrix at different Fe wt%. Such results indicate the possibility to control the band gap of a single-site photocatalyst （Ti-HMS） by coupling it with the conventional nano-sized Fe catalysts.
文摘A controlled cross-linking polymerization containing intra- and intermolecular reactions was designed based on random coil morphology of macromolecules in solution. The soluble intramolecular cross-linked maeromolecule （ICM） was successfully synthesized in the system with PVA and MDI. We found an especial dissolving phenomenon, namely the semi-soluble phenomenon when some gels dissolved in DMF. The chain growth process of ICMs was investigated by Transmission electron microscopy （TEM） pictures of samples at different reacting times, in addition, TEM pictures show ICMs have three kinds of styles in structure, viz. ＂globule structure＂, ＂nubby structure＂ and the intervenient between the above two structures, and the efflux time of the ICMs was measured by an Ubbelohde viscosimeter, it was found that the efflux time decreases with the degree ofcrosslink increasing.
基金supported by the National Basic Research Program of China (973 Program, 2011CB932500)National Natural Science Foundation of China (20932004)
文摘Arnphiphilic cyclodextrin-calixarene conjugates 1 and 2 were synthesized from "click claemxstry, and tnelr sen-asscmuly uchaviors were investigated by transmission electron microscopy, and atomic force microscopy. The results obtained show that 1 and 2 can self-assemble to form distinctly different aggregations, and the morphology of aggregations critically relies on the polarity and hydrophilicity of the solvent.
文摘Manganese selenide （MnSe） possesses unique magnetic properties as an important magnetic semiconductor, but the synthesis and properties of MnSe nanocrystals are less developed compared to other semiconductor nanocrystals because of the inability to obtain high-quality MnSe, especially in the metastable wurtzite structure. Here, we have successfully fabricated wurtzite MnSe nanocrystals via a colloidal approach which affords uniform crystal sizes and tailored shapes. The selective binding strength of the amine surfactant is the determining factor in shape-control and shape-evolution. Bullet-shapes could be transformed into shuttle-shapes if part of the oleylamine in the reaction solution was replaced by trioctylamine, and tetrapod-shaped nanocrystals could be formed in trioctylamine systems. The three-dimensional （3D） structure of the bullet-shaped nanorods has been demonstrated by the advanced transmission electron microscope （TEM） 3D-tomography technology. High-resolution TEM （HRTEM） and electron energy-loss spectroscopy （EELS） show that planar-defect structures such as stacking faults and twinning along the [001] direction arise during the growth of bullet-shapes. On the basis of careful HRTEM observations, we propose a ＂quadra-twin core＂ growth mechanism for the formation of wurtzite MnSe nanotetrapods. Furthermore, the wurtzite MnSe nanocrystals show low- temperature surface spin-glass behavior due to their noncompensated surface spins and the blocking temperatures increase from 8.4 K to 18.5 K with increasing surface area/volume ratio of the nanocrystals. Our results provide a systematic study of wurtzite MnSe nanocrystals.
