Dendritic Hierarchical Structures Research Articles

Fabrication of hierarchical structures on steel mesh with good superhydrophobicity and anti-corrosion property

Superhydrophobic surface is an effective strategy to prevent corrosion and pollution of stainless steel. Nevertheless, toxic modifying agents are often used to fabricate superhydrophobic surface on stainless steel, which is a great threat to the environment. Here, an environmental- friendly strategy was used for fabricating water-repellent stainless steel mesh with dendritic hierarchical structures through vacuum vapor deposition technology and replacement reaction. The fabricated superhydrophobic surface exhibited water bounce performance and repellency for liquids. Moreover, the good self-cleaning and anti-stain properties against contaminates and impurities were also displayed. In addition, the electrochemical experiments indicated the superhydrophobic surface obtained better anti-corrosive property compared with pristine stainless steel mesh. The whole preparation process is eco-friendly and easy to control. It is found that the superhydrophobicity can be acquired through heat treatment, without the need of fluorine-containing modified materials, which can prevent environmental pollution. It is expected that the superhydrophobic surface obtained by this method will have a potential application in anti-corrosion and anti-stain fields.

Formation of hierarchical structures of Fe2O3 by the liquid–liquid interface technique

We report the formation of dendritic hierarchical structures of α-Fe2O3 and nanostructures of Fe2O3 by the simple liquid–liquid interface method.

Novel three-dimensional Co3O4 dendritic superstructures: hydrothermal synthesis, formation mechanism and magnetic properties

Well-defined porous Co3O4 nanodendrites have been synthesized by a simple one-pot hydrothermal method combined with subsequent calcination. Importantly, after thermal treatment, the dendritic morphology could be completely preserved. The as-obtained superstructures are characterized by several techniques, such as powder X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoemission spectroscopy, elemental analysis, transmission electron microscopy, high-resolution TEM and magnetometry. On the dendritic hierarchical structures, a number of nanorods with different lengths and widths are connected to the main trunk with a diameter of about 50 nm and length of several micrometers. Each branch is about 0.5–1.0 μm with a width ranging from 100 to 400 nm. The possible formation mechanism was proposed on the basis of the contrasting experiments. It demonstrated that trisodium citrate and acetone play important roles in the synthesis of Co3O4 nanodendrites, while the other reaction parameters, such as reaction temperature, concentration of trisodium citrate and reaction time, have close relationships with the final morphology of the Co3O4 products. Optical properties of Co3O4 nanodendrites were characterized by Raman and UV-vis spectroscopy. Magnetic property measurement shows that Co3O4 nanodendrites have a low Neel transition temperature of 35 K. The as-prepared mesoporous Co3O4 nanostructures are expected to have great applications in many fields.

Shape-Controlled Preparation of PbS with Various Dendritic Hierarchical Structures with the Assistance of l-Methionine

PbS fishbone-like architectures were synthesized by using a biomolecule (l-methionine)-assisted approach in a mixture solvent made of ethanolamine (EA) and distilled water. Additionally, other PbS homogeneous morphologies (e.g., hexapod-like, coralloid, and dendritic) were obtained through altering the experimental parameters, such as the molar ratio of the reactants and the volume ratio of the mixture solvent. It is noteworthy that our experiments were envionmentally friendly, because no disgusting scent (H2S) appeared in our experiments, which could be hardly avoided in other previous reports. The as-prepared PbS products were examined by using XRD, FESEM, TEM, HRTEM, SAED, and PL. Furthermore, a possible growth mechanism (an initial nucleating stage and a subsequent growth stage) was proposed to explain the formation of dendritic architectures on the basis of TEM observations, XRD, and FTIR analyses. Up to now, this is the first case of the direct growth of novel PbS with various hierarchical nanostructures with l-methionine’s assistance. The synthesized PbS fishbone-like structure was found to indicate strong photoluminescence in the blue-light range.

Single Crystalline FeNi3 Dendrites: Large Scale Synthesis, Formation Mechanism, and Magnetic Properties

Single crystalline FeNi3 dendrites were successfully synthesized in high yield by a simple and facile hydrothermal method without the presence of surfactants and were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometer (VSM). The individual FeNi3 dendrite consists of a long central trunk with secondary, tertiary, and even quaternary branches. On the dendritic hierarchical structures, several leaves with different lengths of 0.2−2.5 μm and widths of 100 nm to 1 μm are connected to the trunk with a length of 1−5 μm. The reaction parameters such as temperature, the reaction time, the concentration of NaOH, and the initial concentration of Fe3+ ions that affected the FeNi3 morphology were investigated systematically, based on which possible formation mechanism for the dendrites was proposed. Compared with FeNi3 particles, FeNi3 dendritic structures exhibited a decreased saturation magnetization (Ms, 61.6 emu/g) but an enhanced coercivity (Hc, 145.6 Oe) due to their peculiar morphology. To our best knowledge, this is the first report on making crystalline metal alloy dendrites with such a full control.

Synthesis and Characterization of Novel Three-Dimensional Metallic Co Dendritic Superstructures by a Simple Hydrothermal Reduction Route

Novel three-dimensional (3D) Co dendritic superstructures with an average diameter of ca. 15 µm were successfully prepared by a simple hydrothermal reduction route. The as-obtained products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometry. It was shown that the 3D Co superstructures were comprised of dozens of well-aligned metallic Co dendrites with hierarchical assemblies radiating from the center. On the dendritic hierarchical structures, several leaves with different lengths and widths are connected to the main branch. The length of the main branch is several micrometers, and that of each leaf is about 0.5–1.5 µm with a width of 100−600 nm. A rational formation mechanism was proposed on the basis of the contrasting experiment. Compared with bulk cobalt, the 3D Co superstructures exhibited a decreased saturation magnetization (Ms) but an enhanced coercivity (Hc) due to their peculiar morphology.

Synthesis of silver dendritic hierarchical structures and transformation into silver nanobeltsthrough an ultrasonic process

Silver dendritic hierarchical structures have been synthesized simply bycarrying out the silver mirror reaction on the surface of a porous anodicaluminium oxide (AAO) template in a surfactant-free system. The length of thestem is several tens of micrometres, and that of each leaf ranges from 0.5 to4 µm with a width of 100–300 nm. Our studies indicate that the growth mechanism of silverdendritic hierarchical structures is a diffusion-limited preferential growth of orientedattachment of silver nanocrystals. Also, the surface of the AAO template has a guidingeffect in the formation process of the silver dendritic hierarchical nanostructure. We haveobserved the transformation from sliver dendritic hierarchical structures to silver nanobeltsunder ultrasonic treatment. This transformation is due to the dissociation of silverdendritic hierarchical structures covering over the Ag nanobelts under ultrasonictreatment.

Self-assembled Silver Dendritic Nanostructure on the Surface of AAO Template

Abstract Silver dendritic hierarchical structures have been prepared using a simple, surfactant-free method by carrying out the silver mirror reaction on the surface of a porous anodic aluminium oxide (AAO) template. The surface of the AAO template has a guiding effect in the formation process of silver dendritic hierarchical structures.