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TiO2纳米晶多孔微球具有颗粒大、晶粒尺寸小及比表面积较高等优点．以明胶作为模板，以钛酸丁酯为原料，采用溶胶?凝胶法制备了TiO2纳米晶多孔微球，并采用透射电镜、X射线衍射仪对其性能进行了表征．实验结果表明：采用溶胶?凝胶法成功制备了纯锐钛矿型TiO2；明胶的加入对样品的物相组成没有影响，但改变了其晶粒尺寸和排布方式，得到了一种由纳米晶组成的多孔微球；微球直径约为200～500 nm，其中孔隙约为2～5 nm，平均晶粒尺寸为（14?3±0?9） nm．在此基础上对TiO2纳米晶多孔微球的形成机理进行了分析．

Suzuki-Miyaura reactions, involving the activation of carbon-halogen bonds, especially C-C1 bonds, have drawn widespread attention because of their huge industrial potential. However, these reactions are dependent on the development of highly active and stable catalysts. Herein, we developed a convenient one-pot wet route to synthesize PdxCuy bimetallic nanocrystals for the Suzuki-Miyaura reaction. By introducing Cu, an earth-abundant element, the catalytic activity was greatly enhanced while the amount of Pd required was reduced. PdxCuy nanocrystals of different compositions, including PdBCu, Pd2Cu, PdCu, PdCu2, and PdCu3, were successfully synthesized by tuning the Pd：Cu ratio. Their catalytic performance in Suzuki-Miyaura reactions between phenylboronic acid and halobenzenes （iodo-, bromo-, or chlorobenzene） showed that PdCua nanocatalyst demonstrated the best efficacy.

A cost-efficient and stable oxygen evolution electrocatalyst is essential for improving energy storage and conversion efficiencies. Herein, 2D nanosheets with randomly cross-linked CoNi layered double hydroxide （LDH） and small CoO nanocrystals were designed and synthesized via in situ reduction and interface- directed assembly in air. The formation of CoNi LDH/CoO nanosheets was attributed to the strong extrusion of hydrated metal-oxide clusters driven by the interfacial tension. The obtained loose and porous nanosheets exhibited low crystallinity due to the presence of numerous defects. Owing to the orbital hybridization between metal 3d and O 2p orbitals, and electron transfer between metal atoms through Ni-O-Co, a number of Co and Ni atoms in the CoNi LDH present a high ＋3 valency. These unique characteristics result in a high density of oxygen evolution reaction （OER） active sites, improving the affinity between OH- and catalyst, and resulting in a large accessible surface area and permeable channels for ion adsorption and transport. Therefore, the resulting nanosheets exhibited high catalytic activity towards the OER. The CoNi LDH/CoO featured a low onset potential of 1.48 V in alkaline medium, and required an overpotential of only 300 mV at a current density of 10 mA.cm-2, while displaying good stability in accelerated durability tests.

The catalytic activity of noble-metal nanocrystals is mainly determined by their sizes and the facets exposed on the surface. For single crystals, it has been demonstrated that the Pd（100） surface is catalytically more active than both Pd（110） and Pd（111） surfaces for the CO oxidation reaction. Here we report the synthesis of Pd nanocrystals enclosed by {100} facets with controllable sizes in the range of 6-18 nm by manipulating the rate of reduction of the precursor. UV-vis spectroscopy studies indicate that the rate of reduction of Na2PdC14 can be controlled by adjusting the concentrations of Br- and C1- ions added to the reaction mixture. Pd nanocrystals with different sizes were immobilized on ZnO nanowires and evaluated as catalysts for CO oxidation. We found that the activity of this catalytic system for CO oxidation showed a strong dependence on the nanocrystal size. When the size of the Pd nanocrystals was reduced from 18 nm to 6 nm, the maximum conversion rate was significantly enhanced by a factor of -10 and the corresponding maximum conversion temperature was lowered by -80℃.

Nanocrystals of Rh, an important member of the noble metal catalyst family, have wide applications in heterogeneous catalytic reactions. Controlling the morphology of these noble metal nanocrystals has become an effective strategy for improving their catalytic activity and durability. In this work, well-defined Rh nanodendrites with very thin triangular branches as subunits are synthesized using a facile diethylene glycol reduction method, assisted by polyethyleneimine as a complex-forming agent and surfactant. For the first time, the methanol oxidation reaction （MOR） on Rh nanocrystals with a well-defined morphology is investigated using various electrochemical techniques in an alkaline medium. Unexpectedly, the as-prepared Rh nanodendrites, with ultrathin nanosheet subunits, exhibit superior electrocatalytic activity and durability during the MOR in an alkaline medium, indicating that Rh nanocrystals with specific morphology may be highly promising alternatives to Pt electrocatalysts in the MOR in an alkaline medium.

The controlled synthesis of gold nanocrystals has been the subject of intensive studies for decades because the properties and functions of gold nanomaterials are highly dependent on their particle size, shape, and dimensionality. Especially, anisotropic gold nanocrystals, such as nanowires, nanobelts, nanoplates and nanosheets, have attracted much attention due to their striking properties and promising applications in electronics, catalysis, photonics, sensing and biomedicine. In this review, we will summarize the recent developments of one- dimensional （1D） and two-dimensional （2D） gold nanostructures. Various kinds of synthetic methods for preparation of these 1D and 2D gold nanocrystals will be described. Moreover, we will also briefly introduce the properties and potential applications of these 1D and 2D gold nanocrystals.

Rhodium （Rh） is a critical component of many catalysts for a variety of chemical transformation processes. Controlling the shape of Rh nanocrystals offers an effective route to the optimization of their catalytic performance owing to a close correlation between the catalytic activity/selectivity and the surface atomic structure. It also helps to substantially reduce the loading amount and thus achieve a sustainable use of this scarce and precious metal. In this review article, we focus on recent progress in the shape-controlled synthesis of Rh nanocrystals with the goal of enhandng their catalytic properties. Both traditional and newly- developed synthetic strategies and growth mechanisms will be discussed, including those based on the use of surface capping agents, manipulation of reduction kinetics, control of surface diffusion rate, management of oxidation etching, and electrochemical alteration. We also use two examples to highlight the unique opportunities offered by shape-controlled synthesis for enhancing the use of this metal in catalytic applications. The strategies can also be extended to other precious metals in an effort to advance the production of cost-effective catalysts.

The ability to controlled introduction of defects, particularly twin defects in Pt-based nanocrystals （NCs） provides a possibility to regulate the performance of Pt-based nanocatalyst. However, because of the high internal strain energy existed in twinned structures, the fabrication of defects in Pt-based NCs is sufficiently challenging. Here we demonstrate a ＂low-temperature interface-induced assembly＂ approach that provides precise control over Pt-Cu nanoparticles assembled at the hexadecylamine/water interface, yielding onion-like Pt-Cu NCs exposed a high density of twin defects. Moreover, a bending mechanism is proposed to elucidate the appearance of twin defects and lattice expanding （contraction） based on aberration corrected scanning transmission electron microscopy analysis. This work opens new routes to engineer defects in metal- based alloy NCs, enabling more opportunities in catalysis.

Lithium iron phosphate （LiFePO4） is a potential high efficiency cathode material for lithium ion batteries, but the low electronic conductivity and single diffusion channel for lithium ions require good particle size and shape control during the synthesis of this material. In this paper, six LiFePO4 nanocrystals with different size and shape have been successfully synthesized in ethylene glycol. The addition sequence Fe-PO4-Li helps to form LiFePO4 nanocrystals with mostly {010} faces exposed, and increasing the amount of LiOH leads to a decrease in particle size. The electrochemical performance of the six distinct LiFePO4 particles show that the most promising LiFePO4 nanocrystals either have predominant {010} face exposure or high specific area, with little iron（II） oxidation.

Against general wisdom in crystallization, the nucleation of InP and III-V quantum dots （QDs） often dominates their growth. Systematic studies on InP QDs identified the key reason for this： the dense and tight alkanoate-ligand shell around each nanocrystal. Different strategies were explored to enable necessary ligand dynamics--i.e., ligands rapidly switching between being bonded to and detached from a nanocrystal upon thermal agitation--on nanocrystals to simultaneously retain colloidal stability and allow appreciable growth. Among all the surface-activation reagents tested, 2,4-diketones （such as acetylacetone） allowed the full growth of InP QDs with indium alkanoates and trimethylsilylphosphine as precursors. While small fatty acids （such as acetic acid） were partially active, common neutral ligands （such as fatty amines, organophosphines, and phosphine oxides） showed limited activation effects. The existing amine-based synthesis of InP QDs was activated by acetic acid formed in situ. Surface activation with common precursors enabled the growth of InP QDs with a distinguishable absorption peak between ~450 and 650 nm at mild temperatures （140-180 ~C）. Furthermore, surface activation was generally applicable for InAs and III-V based core/shell QDs.