Novel Hierarchical Nanostructures of Nickel:  Self-Assembly of Hexagonal Nanoplatelets

Abstract

Novel hierarchical nanostructures of nickel, which were assembled by well-aligned hexagonal nanoplatelets, were fabricated through a simple solution method. The process involved the reduction of nickel dimethylglyoximate with hydrazine under controlled conditions. Based on a series of contrast experiments, the formation mechanism of the flowers was proposed, which could be ascribed to the cooperative effect of the complexant of dimethylglyoxime, a proper reaction rate, and inherent magnetic interactions. The present work provided an example for the synthesis of magnetic assembly nanostructures through properly selection of the reaction conditions, which were independent of any surfactants or external magnetic field.

Non‐Aqueous Sol–Gel Approach towards the Controllable Synthesis of Nickel Nanospheres, Nanowires, and Nanoflowers

“…[5,6] Take for example the case of Ni nanostructures, which are usually synthesized in aqueous solution via the reduction of Ni 2+ ions by chemical or electrodeposition methods. [7][8][9][10] Although aqueous approaches towards the synthesis of Ni nanostructures have been very successful, they still have some limitations. For example, the reaction system is rather complex and parameters such as the pH, concentration of metal ions, and temperature need to be carefully controlled.…”

Ammonia‐Assisted Fabrication of Flowery Nanostructures of Metallic Nickel Assembled from Hexagonal Platelets

“…[37,38] Such an H c value was also superior to that of the counterparts prepared from the dmgH system and nonaqueous sol-gel approach, which was believed to be associated with the unique packing manner of the singly crystalline nanoplatelets in the hierarchical nanostructures. [20,25] This value, however, was much lower than that of the 1D nanorods (332 Oe) or nanobelts (640 Oe), which might be due to the fact that the flowery configuration as a total exhibited a much lower anisotropy than isolated 1D nanocrystals. [39,40] When subjected to an external magnetic field, it was difficult for the radially orientated petals to be aligned simultaneously along the direction of the magnetic field like isolated nanorods or wires.…”

“…Recently, we reported the fabrication of a series of assembly nickel nanostructures without any surfactants or external magnetic field. [23][24][25] The present work, as a continuation of our research endeavor in this area, reports another simple and time-saving method for the synthesis of a new type of nickel assembly nanostructures independent of any surfactants or external magnetic forces. The process involves the reduction of nickelous salt with hydrazine in ammonia solution within 4 h. By properly adjusting the experimental parameters, we realized the anisotropic growth of face-centered-cubic (fcc) nickel into hexagonal nanoplatelets and their simultaneous assembly into flowery architectures.…”

“…In our previous work, another kind of assembly nickel nanostructure with similar morphology was prepared in the system with dimethylglyoxime (dmg) as the complexing agent instead of ammonia, but the size was much smaller (about 1 µm) and the packing of the platelets were overlapped not crossbedded. [25] It was found that the two reaction systems both underwent a solid-solution-solid process, but the reaction rate was much different. The similar morphology was possible due to the similar reaction process, in which dmgH and ammonia both acted as the complexing agent and structure-directing agent with the same coordinating nitrogen atom except that ammonia played the additional role of alkali source.…”

Controlled synthesis of hierarchical CuS architectures by a recrystallization growth process in a microemulsion system

“…Various hierarchical architecture materials such as metal [4], metal oxide [5,6], sulfide [7,8], hydrate [9], and other inorganic materials [10,11] have been successfully synthesized. A solution phase chemical method was one of the most important routes to prepare hierarchical structures because of its low cost and potential advantage for large-scale production [12][13][14].…”