Xintao Luo

Hydrazine-Mediated Construction of Nanocrystal Self-Assembly Materials

Self-assembly is the basic feature of supramolecular chemistry, which permits to integrate and enhance the functionalities of nano-objects. However, the conversion of self-assembled structures to practical materials is still laborious. In this work, on the basis of studying one-pot synthesis, spontaneous assembly, and in situ polymerization of aqueous semiconductor nanocrystals (NCs), NC self-assembly materials are produced and applied to design high performance white light-emitting diode (WLED). In producing self-assembly materials, the additive hydrazine (N2H4) is curial, which acts as the promoter to achieve room-temperature synthesis of aqueous NCs by favoring a reaction-controlled growth, as the polyelectrolyte to weaken inter-NC electrostatic repulsion and therewith facilitate the one-dimensional self-assembly, and in particular as the bifunctional monomers to polymerize with mercapto carboxylic acid-modified NCs via in situ amidation reaction. This strategy is versatile for mercapto carboxylic acid-modified aqueous NCs, for example CdS, CdSe, CdTe, CdSe(x)Te(1-x), and Cd(y)Hg(1-y)Te. Because of the multisite modification with carboxyl, the NCs act as macromonomers, thus producing cross-linked self-assembly materials with excellent thermal, solvent, and photostability. The assembled NCs preserve strong luminescence and avoid unpredictable fluorescent resonance energy transfer, the main problem in design WLED from multiple NC components. These advantages allow the fabrication of NC-based WLED with high color rendering index (86), high luminous efficacy (41 lm/W), and controllable color temperature.

One-pot, seedless synthesis of flowerlike Au–Pd bimetallic nanoparticles with core-shell-like structure via sodium citrate coreduction of metal ions

Bimetallic nanoparticles (NPs) comprised of gold (Au) and palladium (Pd) are promising catalysts in accelerating a variety of chemical reactions. The further performance enhancement greatly depends on the current efforts to create the synthetic methodology for optimizing NP morphology and structure. Here we report a one-pot and seedless synthesis of Au–Pd bimetallic NPs via citrate coreduction of Au and Pd ions. Due to the higher capacity of citrate in reducing Au ions, the nucleation of Au NPs is more favored than that of Pd. Consequently, the current system permits the production of bimetallic NPs with core-shell-like structure, namely an Au-rich core and Pd-rich shell. Moreover, the morphology of the as-synthesized NPs is also determined by the experimental variables, such as the Au-to-Pd feed ratio, dosage of sodium citrate, and charging sequence. With a good control of the nucleation and growth process, flowerlike Au–Pd bimetallic NPs with core-shell-like structures are synthesized. These flowerlike bimetallic NPs are the best in catalyzing formic acid oxidation and Suzuki coupling reaction in comparison to the Au–Pd bimetallic NPs with other morphologies.

Gold nanoparticle superstructures with enhanced photothermal effect

Gold (Au) nanomaterials are promising photothermal therapeutic agents for the selective treatment of tumor cells. Further development of correlated techniques greatly depends on the current efforts to enhance the photothermal performance by fabricating novel Au architectures. In this work, water-dispersible spherical superstructures are constructed from original hydrophobic Au nanoparticles (NPs) in place of oil droplets in microemulsion as the templates. Different from the previous reports, Pluronic F127, a nonionic triblock copolymers of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide), is employed as the capping agent to directly make the superstructures biocompatible. However, due to the nonionic nature, it is difficult to control the size and morphology of Au superstructures using F127 alone. Additional positive surfactants, such as octadecyl-p-vinylbenzyldimethylammonium chloride, are necessary to assist Au superstructure formation in a controlled manner. The as-prepared Au superstructures, which possess enhanced absorption the in red and near-infrared region, exhibit more efficient photothermal behavior in comparison to individual Au NPs.

Shape-selective synthesis and facet-dependent electrocatalytic activity of CoPt3 nanocrystals

Testing the facet-dependent electrocatalytic activity of noble metal alloy nanocrystals has attracted increasing interest towards improving the performance of direct methanol fuel cells. Herein, CoPt3 nanocrystals with high shape- and facet-selectivity are synthesized via a non-injection strategy. The (111)-facet-dominant nanoflowers are more active for catalytic oxidation of methanol than the (100)-facet-dominant nanocubes and nanoparticles with irregular facets.

Au-Edged CuZnSe2 Heterostructured Nanosheets with Enhanced Electrochemical Performance

Two-dimensional (2D) nanomaterials and heterostructured nanocrystals (NCs) are two hot topics in current nanoresearch. However, reports on heterostructured NCs with 2D features are still rare. In this work, we demonstrate a one-pot colloidal chemistry route for synthesizing Au-CuZnSe2 heterostructures with spherical Au domains attached to the edge of a sheet of CuZnSe2 . This protocol involves the preferential formation of Au clusters and the seeded growth of CuZnSe2 sheets because of the lattice matching of CuSe with Au. As an example to demonstrate the importance of such heterostructures, the electrochemical performance of Au-CuZnSe2 heterostructured nanosheets is compared with that of heterostructured nanorods, Au NCs, and CuZnSe2 NCs. The heterostructured nanosheets exhibit the best electrochemical activity.