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Enhancement of Red Upconversion Emission of LiGdF <sub/>4</sub> :Yb <sup>3+</sup> /Ho <sup>3+</sup> Nanorods by Doping with Ce <sup>3+</sup>
摘要： A series of tetragonal phase LiGdF4:Yb3+/Ho3+ nanorods tri-doped with Ce3+ have been successfully prepared via a facile oil heated method at 200 °C. The visible green and red upconversion emissions have been achieved and the red emission intensity is enhanced gradually with increasing Ce3+ concentration. The ratio of red to green emission of the Ho3+ ions is boosted about 20-fold due to efficient cross relaxation processes between Ho3+ and Ce3+ ions, which promote the red emission and weaken the green emission. The crystal phase and morphology of the nanorod samples were inspected by X-ray diffraction and transmission electron microscopy, respectively. This work has great potential applications in the biological imaging, biomedical and color display applications.
关键词： Energy Transfer,Upconversion Luminescence,Nanorods LiGdF4
更新于2025-09-04 15:30:14
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Structural, Morphological and Photocatalytic Activity of YMnO <sub/>3</sub> Nanorods
摘要： In this work rod-like YMnO3 were successfully prepared by hydrothermal method. The crystal structure and morphology of prepared samples were characterized by X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structural information was confirmed from Raman spectrum and the functional group of the sample was studied from FT-IR spectrum. X-ray photoelectron spectroscopy studies confirm the formation and oxidation states of YMnO3. The optical properties of the prepared samples were investigated using UV-vis spectroscopy. The photocatalytic activity of YMnO3 nanorods was evaluated by degradation of methyl orange (MO) under both ultraviolet and visible-light irradiation. The result shows that the YMnO3 nanorods exhibit maximum photocatalytic activity in the degradation of MO.
关键词： YMnO3 Nanorods,Hydrothermal,Methyl Orange,Photocatalytic
更新于2025-09-04 15:30:14
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Preparation, Characterization, and Photocatalytic Activity of LaMnO3 Nanorods-reduced Graphene Oxide Composite
摘要： Background: A new type of photocatalyst with a perovskite structure is recently utilized. The one-dimensional nanostructure of photocatalysts holds great charge mobility along the crystal longitudinal dimension and can hence provide the direct pathways of charge carriers. Graphene holds a superior electrical conductivity and high specific surface area. The aims of this paper are to make LaMnO3 nanorods disperse on the graphene surface. The synergistic effect between graphene and LaMnO3 nanorods enhances the photocatalytic performance. Method: LaMnO3 nanorods–graphene is fabricated using cetyltrimethyl ammonium bromide as template by a simple hydrothermal reaction followed by heat treatment. Results: XRD result indicates that the appropriate calcination temperature for the perovskite structure formation is 650°C. Electron microscopy reveals the LaMnO3 nanorods exhibit a good dispersion behavior on the surface of graphene and the specific surface area of LaMnO3 nanorods-graphene is higher than that of LaMnO3 nanorods. The activities of LaMnO3 nanorods–graphene and TiO2 are compared for degradation of Direct Green BE, the decolorizing rates are 99.93% and 79.45%, respectively. Conclusion: The photocatalytic results for Direct Green BE degradation showed that LaMnO3 nanorods–reduced graphene oxide exhibit a superior photocatalytic performance than that of LaMnO3 nanorods and TiO2 powders. The one-dimensional nanorod structure of LaMnO3 can provide a direct pathway for electronic transmission, and the increased aspect ratio is favorable for reducing the recombination probability of the electron and hole. Meanwhile, the photoelectron transport along the graphene sheets can promote the separation of the e?–h+ pairs.
关键词： Perovskite,nanorods,hydrothermal reaction,composite,photocatalysis,graphene
更新于2025-09-04 15:30:14
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Studies of Surface Electrical Properties of Al doped ZnO Nanorods by STM
摘要： Pure and aluminum (Al) doped ZnO (Al:ZnO) nanorods (NRs) were deposited on silicon substrates by the hydrothermal method. The Al composition was kept at 2 % and 5 % for the Al:ZnO NR samples. The surface morphology and structural properties of the pure and Al:ZnO NRs were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The XRD study revealed the hexagonal phase of the ZnO with (101), (002) and (100) peaks and it also revealed that the major orientation of ZnO NRs was along the (002) planes. The SEM micrographs showed perfectly grown ZnO NRs with hexagonal shaped tips. The electrical characterization of the pure and Al:ZnO NR thin film surface was done by scanning tunneling microscopy (STM). Local electron spectroscopy was conducted to measure the tunneling current with respect to the applied bias. The n-type behavior and bandgap of the pure and Al:ZnO NRs were confirmed from the dI/dV – V characteristics. These studies are of fundamental importance for the fabrication of pure and Al:ZnO NR based nanodevices.
关键词： X-ray diffraction,Al doped ZnO,scanning tunnelling microscopy,nanorods,hydrothermal
更新于2025-09-04 15:30:14
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Observed Dramatically Improved Catalysis of Ag Shell on Au/Ag Core-Shell Nanorods is Due to Silver Impurities Released During Etching Process
摘要： Core/shell bimetallic nanoparticles are highly popular in electrocatalysis; it is argued that the core metal enhances the catalytic properties of the shell. We have investigated the electrocatalytic properties of Au/Ag core-shell nanorods (Au/Ag NRs) where Ag shell was thinned by aging in the presence of cetyltrimethylammonium bromide. We observed excellent electrocatalysis toward hydrogen peroxide electroreduction upon decreasing the Ag shell thickness, which would, at first, appear to imply a strong synergistic effect of the Au core with the Ag shell for electrocatalysis. We show, however, that this electrocatalysis is not caused by particular Au/Ag core/shell structures but rather by the presence of residual silver impurities in the form of Ag nanoparticles (Ag NPs) formed during the preparation of the thin-layer silver shell/gold core nanorods.
关键词： bimetallic particles,Au/Ag nanorods,varied shell thickness,physicochemical transformation,hydrogen peroxide catalyst
更新于2025-09-04 15:30:14
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Charge‐Induced Shifts in Chiral Surface Plasmon Modes in Gold Nanorod Assemblies
摘要： A detailed investigation of the effect of electron injection on the chiral plasmon modes of helical nanorod assemblies is presented. An increased surface plasmon frequency of the electron gas due to the addition of electrons leads to a blue-shift in the corresponding chiral surface plasmon modes. The mechanism behind the shift in plasmonic chirality due to nanorod charging is investigated using theoretical simulations. Charging of the nanorods alters the surface electron density, thereby modifying the plasma frequency and causing a change in the dielectric function. The nature of the plasmon shift and the intensity of chiral surface plasmons are found to be largely dependent on the extent of electron addition. At extended periods of time, the blue shifted band slowly shifts back toward the red, due to transfer of electrons back to the medium, leading to discharging of the nanorods.
关键词： charging effects,plasmonic chirality,electromagnetic modeling,Au nanorods,amyloid fibers
更新于2025-09-04 15:30:14
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The Quantum Efficiency of Charge Transfer Competing Against Non-Exponential Processes: The Case of Electron Transfer from CdS Nanorods to Hydrogenase
摘要： Photoexcited charge transfer from semiconductor nanocrystals to charge acceptors is a key step for photon energy conversion in semiconductor nanocrystal-based light-harvesting systems. Charge transfer competes against relaxation processes within the nanocrystals, and this competition determines the quantum efficiency of charge transfer. The quantum efficiency is a critical design element in photochemistry, but in nanocrystal–acceptor systems its extraction from experimental data is complicated by sample heterogeneity and intrinsically non-exponential excited-state decay pathways. In this manuscript, we systematically explore these complexities using TA spectroscopy over a broad range of timescales to probe electron transfer from CdS nanorods to the redox enzyme hydrogenase. To analyze the experimental data, we build a model that quantifies the quantum efficiency of charge transfer in the face of competing, potentially non-exponential, relaxation processes. Our approach can be applied to calculate the efficiency of charge or energy transfer in any donor–acceptor system that exhibits non-exponential donor decay and any ensemble distribution in the number of acceptors provided that donor relaxation and charge transfer can be described as independent, parallel decay pathways. We apply this analysis to our experimental system and unveil the connections between particle morphology and quantum efficiency. Our model predicts a finite quantum efficiency even when the mean recombination time diverges, as it does in CdS nanostructures with spatially separated electron–hole pairs that recombine with power-law dynamics. We contrast our approach to the widely-used expressions for the quantum efficiency based on average lifetimes, which for our system overestimate the quantum efficiency. The approach developed here is straightforward to implement and should be applicable to a wide range of systems.
关键词： electron transfer,quantum efficiency,semiconductor nanocrystals,non-exponential processes,charge transfer,hydrogenase,CdS nanorods
更新于2025-09-04 15:30:14
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Visualization of Endogenous Hydrogen Sulfide in Living Cells based on Au Nanorods@Silica Enhanced Fluorescence
摘要： Hydrogen sulfide as a gas indicator molecule plays an important role in various human physiological processes. However, due to the high volatility and diffusivity of H2S in biological systems, it is very difficult to implement a precise assay for H2S detection. Compared with the destructive instrumental methods, assays based on fluorescence probes provide noninvasive and real-time detections of H2S in living cells. In this work, we presented a fluorescent nanoprobe based on dye-functionalized Au nanorods (NRs)@silica for sensitive and selective detection of H2S in vitro and living cells. With the metal enhanced fluorescence effect, the fluorescence turn-on and turn-off were controlled by the formation and disassembly of coordination compound between dyes and copper ions. Silica matrix was used to coat the Au NRs to prevent them from the biological cytotoxicity. The effects of the different distances between Au NRs and fluorophores on fluorescent enhancement were explored and approximately 5-fold fluorescence enhancement was obtained with a distance of 22 nm. A detection of limit of 17 nM was achieved. In addition, visualization of exogenous and endogenous H2S in living cells was validated.
关键词： nanoprobes,Au nanorods@silica,metal enhanced fluorescence,living cells,endogenous H2S
更新于2025-09-04 15:30:14
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In vivo and in vitro demonstration of gold nanorod aided photothermal pre-softening of B16F10 melanoma for efficient chemotherapy using Doxorubicin loaded Graphene Oxide
摘要： A combined photothermal therapy (PTT), and chemotherapy (chemo) was performed in vitro on B16F10 melanoma cells, and in vivo using melanoma bearing C57BL/6 mice. 785 nm (100 mW) irradiated gold nanorods (AuNRs) was used as the PT agent, and electrostatically conjugated Doxorubicin (Dox) to a nanocarrier graphene oxide (GO) worked as the chemotherapeutic. Selection of dosage was optimized from the individual viability studies, and finally a combined therapeutic (AuNR (100 ppm), GO (125, and 250 ppm), Dox (0.0058, and 0.00058 ppm)), was delivered in vitro. PTT, followed by chemo, sequentially, resulted in <10 % viability, whereas simultaneous PTT with chemo resulted in a viability of ~40 % for the melanoma cells. Flow cytometry indicated optical inhomogeneity in the cells that internalized GO, and AuNR, however, the Dox amount was identical within the cells treated with or without PTT. Confocal microscopy revealed that GO-Dox was internalized, and Dox was distributed uniformly within the cells irrespective of the treatment protocol. In vivo results in melanoma bearing C57BL/6 mice resembled the in vitro data closely. The tumor growth inhibition index was highest at 0.78 for the group receiving sequential treatment, followed by 0.61 for those receiving simultaneous treatment, where the control group had a score of 0. For the sequential treatment, pre-softening of the cells with PTT, followed by the chemo resulted in significantly improved toxicity of the treatment, whereas simultaneous PTT, with chemo results were dominated by the Dox alone.
关键词： Nanomedicine,Graphene Oxide,Photothermal therapy,Melanoma,Drug delivery,Gold Nanorods
更新于2025-09-04 15:30:14
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Zinc Oxide Nanorods Wrapped with Ion-Imprinted Polypyrrole Polymer for Picomolar Selective and Electrochemical Detection of Mercury II Ions
摘要： This study concerns the design of an ion-imprinted polymer (IIP) for the selective detection of mercury II ions. Compared to other electrochemical studies, the originality of this work lies to the fact that the IIP was electropolymerized on ZnO nanorods, which were themselves grown on gold/diazonium modified substrates. This strategy of diazonium salt and ZnO nanorods permits to increase considerably the specific surface and thus to improve the sensor’s performances. The limit of detection (LOD) of the designed sensor was of order of 1 pM, the lowest value ever reported in literature.
关键词： mercury,electrochemical detection,ionic imprinted polymer,zinc oxide nanorods
更新于2025-09-04 15:30:14