A catechol based polyethyleneglycol brush polymer was nano-coated on ultrasmall iron oxide nanopa... more A catechol based polyethyleneglycol brush polymer was nano-coated on ultrasmall iron oxide nanoparticles through amine mediated redox modulation of catechol. High-resolution in vivo T1 angiography with a long circulation time was achieved.
The surface charge of iron oxide nanoparticles (IONPs) plays a critical role in the interactions ... more The surface charge of iron oxide nanoparticles (IONPs) plays a critical role in the interactions between nanoparticles and biological components, which significantly affects their toxicity in vitro and in vivo. In this study, we synthesized three differently charged IONPs (negative, neutral, and positive) based on catechol-derived dopamine, polyethylene glycol, carboxylic acid, and amine groups, via reversible addition–fragmentation chain transfer-mediated polymerization (RAFT polymerization) and ligand exchange. The zeta potentials of the negative, neutral, and positive IONPs were −39, −0.6, and +32 mV, respectively, and all three IONPs showed long-term colloidal stability for three months in an aqueous solution without agglomeration. The cytotoxicity of the IONPs was studied by analyzing cell viability and morphological alteration in three human cell lines, A549, Huh-7, and SH-SY5Y. Neither IONP caused significant cellular damage in any of the three cell lines. Furthermore, the IO...
Significant aggregation between ZnO nanoparticles (ZnO NPs) dispersed in polar and nonpolar solve... more Significant aggregation between ZnO nanoparticles (ZnO NPs) dispersed in polar and nonpolar solvents hinders the formation of high quality thin film for the device application and impedes their excellent electron transporting ability. Herein a bifunctional coordination complex, titanium diisopropoxide bis(acetylacetonate) (Ti(acac)2) is employed as efficient stabilizer to improve colloidal stability of ZnO NPs. Acetylacetonate functionalized ZnO exhibited long-term stability and maintained its superior optical and electrical properties for months aging under ambient atmospheric condition. The functionalized ZnO NPs were then incorporated into polymer solar cells with conventional structure as n-type buffer layer. The devices exhibited nearly identical power conversion efficiency regardless of the use of fresh and old (2 months aged) NPs. Our approach provides a simple and efficient route to boost colloidal stability of ZnO NPs in both polar and nonpolar solvents, which could enable ...
In this article, the facile synthesis of sea urchin-shaped LiFePO4 nanoparticles by thermal decom... more In this article, the facile synthesis of sea urchin-shaped LiFePO4 nanoparticles by thermal decomposition of metal-surfactant complexes and application of these nanoparticles as a cathode in lithium ion secondary batteries is demonstrated.
Electrode materials exploiting multi-electron transfer processes are essential components for lar... more Electrode materials exploiting multi-electron transfer processes are essential components for large scale energy storage systems. Organic-based electrode materials undergoing distinct molecular redox transformations can intrinsically circumvent the structural instability issue of conventional inorganic-based host materials associated with lattice volume expansion and pulverization. Yet, the fundamental mechanistic understanding of metal-organic coordination polymers toward the reversible electrochemical processes is still lacking. Herein we demonstrate that metal-dependent spatial-proximity and binding affinity play a critical role in the reversible redox processes, as verified by combined C solid-state NMR, X-ray absorption spectroscopy, and transmission electron microscopy. During the electrochemical lithiation, in-situ generated metallic nanoparticles dispersed in the organic matrix generate electrically conductive paths, synergistically aiding subsequent multi-electron transfer ...
We report a strategy toward the synthesis of colloidal nanocrystals capped with inorganic molybde... more We report a strategy toward the synthesis of colloidal nanocrystals capped with inorganic molybdenum and tungsten sulfide ligands. MoS4(2-) and WS4(2-) thiometalates were utilized to replace organic ligands capping a wide range of nanocrystals such as metals, semiconductors, and well-conserved primary properties of nanocrystals in polar media. Especially, MoS4(2-)- and WS4(2-)-capped CdSe nanocryatals showed the dramatic enhancement of photoluminescence properties by the photo-oxidation treatment, which originated from the preferential formation of MoSxOy layers on the CdSe surface. The highest quantum yield reached up to 51%. Furthermore, we studied the charge-transport properties of MoS4(2-)-capped PbS nanocryatals by the fabrication of a field-effect transistor and photodetectors. Finally, MoS4(2-)- and WS4(2-)-capped nanocrystals were used for the production of two-dimensional MoS2 and WS2 thin layers on nanostructures by heat treatment. Such versatility of these thiometalate li...
Small (Weinheim an der Bergstrasse, Germany), Jan 7, 2015
Nano-floating gate memory (NFGM) devices are transistor-type memory devices that use nanostructur... more Nano-floating gate memory (NFGM) devices are transistor-type memory devices that use nanostructured materials as charge trap sites. They have recently attracted a great deal of attention due to their excellent performance, capability for multilevel programming, and suitability as platforms for integrated circuits. Herein, novel NFGM devices have been fabricated using semiconducting cobalt ferrite (CoFe2 O4 ) nanoparticles (NPs) as charge trap sites and pentacene as a p-type semiconductor. Monodisperse CoFe2 O4 NPs with different diameters have been synthesized by thermal decomposition and embedded in NFGM devices. The particle size effects on the memory performance have been investigated in terms of energy levels and particle-particle interactions. CoFe2 O4 NP-based memory devices exhibit a large memory window (≈73.84 V), a high read current on/off ratio (read Ion /Ioff ) of ≈2.98 × 10(3) , and excellent data retention. Fast switching behaviors are observed due to the exceptional ch...
Nickel nitride electrodes were prepared by reactive sputtering of nickel under a N2 atmosphere at... more Nickel nitride electrodes were prepared by reactive sputtering of nickel under a N2 atmosphere at room temperature for application in mesoscopic dye- or quantum dot- sensitized solar cells. This facile and reliable method led to the formation of a Ni2N film with a cauliflower-like nanostructure and tetrahedral crystal lattice. The prepared nickel nitride electrodes exhibited an excellent chemical stability toward both iodide and polysulfide redox electrolytes. Compared to conventional Pt electrodes, the nickel nitride electrodes showed an inferior electrocatalytic activity for the iodide redox electrolyte; however, it displayed a considerably superior electrocatalytic activity for the polysulfide redox electrolyte. As a result, compared to dye-sensitized solar cells (DSCs), with a conversion efficiency (η) = 7.62% and CdSe-based quantum dot-sensitized solar cells (QDSCs, η = 2.01%) employing Pt counter electrodes (CEs), the nickel nitride CEs exhibited a lower conversion efficiency ...
We synthesized manganese oxide (MnO and Mn3O4) nanocrystals with various sizes and shapes by the ... more We synthesized manganese oxide (MnO and Mn3O4) nanocrystals with various sizes and shapes by the thermal reaction of a MnII–oleate complex through a “heat‐up process”. When a MnII–oleate complex was thermally decomposed in non‐coordinating hydrocarbon solvents, uniformly sized MnO nanocrystals with cubic and octahedral shapes were produced. We were able to synthesize anisotropic, multibranched MnO nanocrystals by the oriented attachment of MnO truncated‐nanocube building blocks. When the MnII–oleate complex was heated in 1‐hexadecene in the presence of strongly coordinating carboxylic acid surfactants, spherical nanocrystals were generated, and their diameter was controlled in the range 3–13 nm by varying the chain length of the carboxylic acid. When oleyl alcohol was added to the Mn–oleate complex in phenyl ether, tetrahedral MnO nanocrystals were synthesized. The as‐synthesized MnO nanocrystals were oxidized in air to Mn3O4 or MnO/Mn3O4 core–shell structures, which exhibited excha...
A catechol based polyethyleneglycol brush polymer was nano-coated on ultrasmall iron oxide nanopa... more A catechol based polyethyleneglycol brush polymer was nano-coated on ultrasmall iron oxide nanoparticles through amine mediated redox modulation of catechol. High-resolution in vivo T1 angiography with a long circulation time was achieved.
The surface charge of iron oxide nanoparticles (IONPs) plays a critical role in the interactions ... more The surface charge of iron oxide nanoparticles (IONPs) plays a critical role in the interactions between nanoparticles and biological components, which significantly affects their toxicity in vitro and in vivo. In this study, we synthesized three differently charged IONPs (negative, neutral, and positive) based on catechol-derived dopamine, polyethylene glycol, carboxylic acid, and amine groups, via reversible addition–fragmentation chain transfer-mediated polymerization (RAFT polymerization) and ligand exchange. The zeta potentials of the negative, neutral, and positive IONPs were −39, −0.6, and +32 mV, respectively, and all three IONPs showed long-term colloidal stability for three months in an aqueous solution without agglomeration. The cytotoxicity of the IONPs was studied by analyzing cell viability and morphological alteration in three human cell lines, A549, Huh-7, and SH-SY5Y. Neither IONP caused significant cellular damage in any of the three cell lines. Furthermore, the IO...
Significant aggregation between ZnO nanoparticles (ZnO NPs) dispersed in polar and nonpolar solve... more Significant aggregation between ZnO nanoparticles (ZnO NPs) dispersed in polar and nonpolar solvents hinders the formation of high quality thin film for the device application and impedes their excellent electron transporting ability. Herein a bifunctional coordination complex, titanium diisopropoxide bis(acetylacetonate) (Ti(acac)2) is employed as efficient stabilizer to improve colloidal stability of ZnO NPs. Acetylacetonate functionalized ZnO exhibited long-term stability and maintained its superior optical and electrical properties for months aging under ambient atmospheric condition. The functionalized ZnO NPs were then incorporated into polymer solar cells with conventional structure as n-type buffer layer. The devices exhibited nearly identical power conversion efficiency regardless of the use of fresh and old (2 months aged) NPs. Our approach provides a simple and efficient route to boost colloidal stability of ZnO NPs in both polar and nonpolar solvents, which could enable ...
In this article, the facile synthesis of sea urchin-shaped LiFePO4 nanoparticles by thermal decom... more In this article, the facile synthesis of sea urchin-shaped LiFePO4 nanoparticles by thermal decomposition of metal-surfactant complexes and application of these nanoparticles as a cathode in lithium ion secondary batteries is demonstrated.
Electrode materials exploiting multi-electron transfer processes are essential components for lar... more Electrode materials exploiting multi-electron transfer processes are essential components for large scale energy storage systems. Organic-based electrode materials undergoing distinct molecular redox transformations can intrinsically circumvent the structural instability issue of conventional inorganic-based host materials associated with lattice volume expansion and pulverization. Yet, the fundamental mechanistic understanding of metal-organic coordination polymers toward the reversible electrochemical processes is still lacking. Herein we demonstrate that metal-dependent spatial-proximity and binding affinity play a critical role in the reversible redox processes, as verified by combined C solid-state NMR, X-ray absorption spectroscopy, and transmission electron microscopy. During the electrochemical lithiation, in-situ generated metallic nanoparticles dispersed in the organic matrix generate electrically conductive paths, synergistically aiding subsequent multi-electron transfer ...
We report a strategy toward the synthesis of colloidal nanocrystals capped with inorganic molybde... more We report a strategy toward the synthesis of colloidal nanocrystals capped with inorganic molybdenum and tungsten sulfide ligands. MoS4(2-) and WS4(2-) thiometalates were utilized to replace organic ligands capping a wide range of nanocrystals such as metals, semiconductors, and well-conserved primary properties of nanocrystals in polar media. Especially, MoS4(2-)- and WS4(2-)-capped CdSe nanocryatals showed the dramatic enhancement of photoluminescence properties by the photo-oxidation treatment, which originated from the preferential formation of MoSxOy layers on the CdSe surface. The highest quantum yield reached up to 51%. Furthermore, we studied the charge-transport properties of MoS4(2-)-capped PbS nanocryatals by the fabrication of a field-effect transistor and photodetectors. Finally, MoS4(2-)- and WS4(2-)-capped nanocrystals were used for the production of two-dimensional MoS2 and WS2 thin layers on nanostructures by heat treatment. Such versatility of these thiometalate li...
Small (Weinheim an der Bergstrasse, Germany), Jan 7, 2015
Nano-floating gate memory (NFGM) devices are transistor-type memory devices that use nanostructur... more Nano-floating gate memory (NFGM) devices are transistor-type memory devices that use nanostructured materials as charge trap sites. They have recently attracted a great deal of attention due to their excellent performance, capability for multilevel programming, and suitability as platforms for integrated circuits. Herein, novel NFGM devices have been fabricated using semiconducting cobalt ferrite (CoFe2 O4 ) nanoparticles (NPs) as charge trap sites and pentacene as a p-type semiconductor. Monodisperse CoFe2 O4 NPs with different diameters have been synthesized by thermal decomposition and embedded in NFGM devices. The particle size effects on the memory performance have been investigated in terms of energy levels and particle-particle interactions. CoFe2 O4 NP-based memory devices exhibit a large memory window (≈73.84 V), a high read current on/off ratio (read Ion /Ioff ) of ≈2.98 × 10(3) , and excellent data retention. Fast switching behaviors are observed due to the exceptional ch...
Nickel nitride electrodes were prepared by reactive sputtering of nickel under a N2 atmosphere at... more Nickel nitride electrodes were prepared by reactive sputtering of nickel under a N2 atmosphere at room temperature for application in mesoscopic dye- or quantum dot- sensitized solar cells. This facile and reliable method led to the formation of a Ni2N film with a cauliflower-like nanostructure and tetrahedral crystal lattice. The prepared nickel nitride electrodes exhibited an excellent chemical stability toward both iodide and polysulfide redox electrolytes. Compared to conventional Pt electrodes, the nickel nitride electrodes showed an inferior electrocatalytic activity for the iodide redox electrolyte; however, it displayed a considerably superior electrocatalytic activity for the polysulfide redox electrolyte. As a result, compared to dye-sensitized solar cells (DSCs), with a conversion efficiency (η) = 7.62% and CdSe-based quantum dot-sensitized solar cells (QDSCs, η = 2.01%) employing Pt counter electrodes (CEs), the nickel nitride CEs exhibited a lower conversion efficiency ...
We synthesized manganese oxide (MnO and Mn3O4) nanocrystals with various sizes and shapes by the ... more We synthesized manganese oxide (MnO and Mn3O4) nanocrystals with various sizes and shapes by the thermal reaction of a MnII–oleate complex through a “heat‐up process”. When a MnII–oleate complex was thermally decomposed in non‐coordinating hydrocarbon solvents, uniformly sized MnO nanocrystals with cubic and octahedral shapes were produced. We were able to synthesize anisotropic, multibranched MnO nanocrystals by the oriented attachment of MnO truncated‐nanocube building blocks. When the MnII–oleate complex was heated in 1‐hexadecene in the presence of strongly coordinating carboxylic acid surfactants, spherical nanocrystals were generated, and their diameter was controlled in the range 3–13 nm by varying the chain length of the carboxylic acid. When oleyl alcohol was added to the Mn–oleate complex in phenyl ether, tetrahedral MnO nanocrystals were synthesized. The as‐synthesized MnO nanocrystals were oxidized in air to Mn3O4 or MnO/Mn3O4 core–shell structures, which exhibited excha...
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