25 research outputs found

    One-Pot Synthesis of Biocompatible CdSe/CdS Quantum Dots and Their Applications as Fluorescent Biological Labels

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    We developed a novel one-pot polyol approach for the synthesis of biocompatible CdSe quantum dots (QDs) using poly(acrylic acid) (PAA) as a capping ligand at 240°C. The morphological and structural characterization confirmed the formation of biocompatible and monodisperse CdSe QDs with several nanometers in size. The encapsulation of CdS thin layers on the surface of CdSe QDs (CdSe/CdS core–shell QDs) was used for passivating the defect emission (650 nm) and enhancing the fluorescent quantum yields up to 30% of band-to-band emission (530–600 nm). Moreover, the PL emission peak of CdSe/CdS core–shell QDs could be tuned from 530 to 600 nm by the size of CdSe core. The as-prepared CdSe/CdS core–shell QDs with small size, well water solubility, good monodispersity, and bright PL emission showed high performance as fluorescent cell labels in vitro. The viability of QDs-labeled 293T cells was evaluated using a 3-(4,5-dimethylthiazol)-2-diphenyltertrazolium bromide (MTT) assay. The results showed the satisfactory (>80%) biocompatibility of as-synthesized PAA-capped QDs at the Cd concentration of 15 μg/ml

    Selective Synthesis of Fe2O3 and Fe3O4 Nanowires Via a Single Precursor: A General Method for Metal Oxide Nanowires

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    Hematite (α-Fe2O3) and magnetite (Fe3O4) nanowires with the diameter of about 100 nm and the length of tens of micrometers have been selectively synthesized by a microemulsion-based method in combination of the calcinations under different atmosphere. The effects of the precursors, annealing temperature, and atmosphere on the morphology and the structure of the products have been investigated. Moreover, Co3O4 nanowires have been fabricated to confirm the versatility of the method for metal oxide nanowires

    Oxygen vacancies promoting the electrocatalytic performance of CeO 2 nanorods as cathode materials for Li-O 2 batteries

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    Li-O 2 batteries have become very promising power sources for electronic vehicles as a result of their extraordinary energy density. Nevertheless, the unfavourable electrocatalytic activity of cathode materials in Li-O 2 batteries is still a limiting factor for the practical application of Li-O 2 batteries. This study proposes a surface engineering strategy which can enhance the electrocatalytic activity of CeO 2 nanorods by tuning the oxygen vacancies on their surface, and found that the highest concentration of oxygen vacancies induces the best electrochemical performance, including an extended electrochemical stability of 200 cycles, and reduces the overpotential of the ORR from the reported 0.26 V to 0.11 V. Ex situ XPS photoelectron spectroscopy was carried out to further explain the role of oxygen vacancies in improving the electrochemical performance of LOBs, indicating that the oxygen vacancies of CeO 2 nanorods have more obvious positive effects on the ORR than on the OER. It is believed that they can serve as the active sites for the deposition of Li 2 O 2 films by being involved in the reaction between Li + and O 2 during the ORR, and also boost the electron transport through the insoluble Li 2 O 2 films to further catalyse the Li + and O 2 reaction during the discharge and charge process. This work provides new proof for the association between the discharge/charge behaviour of LOBs and the content of oxygen vacancies

    High performance MnO@C microcages with a hierarchical structure and tunable carbon shell for efficient and durable lithium storage

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    A MnO@C microcage with a multi-structure and tunable carbon shell was fabricated through a facile bio-inspired synthesis strategy for highly reversible Li storage. Micrometer-sized MnO unit aggregates were covered with a porous carbon shell outside with a thickness of about 0.2 μm, and a graphene-analogous carbon network inside the MnO@C microcages. The carbon shell could be tunable by a graphene-base shell. The unique double-carbon-coating structure of the MnO@C microcages enabled realizing the high Li-storage performance of the MnO particles with a micrometer size. The electrode containing the MnO@C microcages delivered a high reversible capacity of 1450.5 mA h g -1 after 270 cycles at a current density of 0.1 A g -1 , good rate capability, and outstanding cycling stability with a retention capacity of 805 mA h g -1 after 2000 cycles at a high current density of 1 A g -1 . Quantitative kinetic analysis indicated that around 40% of the charge storage came from the capacitive contribution of the microcage structure. It was found that the tunable graphene-base shell could enhance the Li-ion diffusion rate significantly, and enable a stable ultralong long life cycle performance and enhanced rate performance of the microcages
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