Crystalline Nanoflowers with Different Chemical Compositions and Physical Properties Grown by Limited Ligand Protection

Abstract

Colloidal nanocrystals with controlled size and shape play a key role in nanotechnology. [1][2][3] Organometallic [4][5][6] and related alternative (or so-called greener) [7][8][9][10] synthetic methods at elevated temperatures in non-aqueous solvents are the current mainstream strategies for producing high-quality nanocrystals. The ability to control the size and size distribution of nanodots using these strategies is reasonably well developed. Also, advances in the formation of 1D nanocrystals have recently been reported. [5,[11][12][13][14] These 1D structures offer a unique technical potential that is inaccessible with the corresponding 0D nanocrystals. Reports on the synthesis of complex 3D nanostructures, however, remain uncommon. [15][16][17][18][19] Most of these structures are grown on substrates, are large in size, and/or are polycrystalline. Herein, we demonstrate that, by simply reducing the degree of ligand protection to the domain of limited ligand protection (LLP), the existing mainstream synthetic chemistry for 0D and 1D nanocrystals-more specifically, the greener approaches-can also produce high-quality complex 3D nanostructures, such as crystalline nanoflowers. Unlike the formation of tetrapods of II-VI semiconductors with specific crystal structures, [15,20] we reveal that LLP coupled with 3D oriented attachment can be applied in the preparation of nanocrystals with different compositions, crystal structures, and physical (magnetic and electronic) properties.The LLP strategy was first applied to the In 2 O 3 nanocrystal system, and it was not clear if the 3D oriented attachment caused by LLP would be limited to certain crystal structures and compositions. Herein, we intend to clarify the generality of the LLP strategy. A detailed account of the nanocrystal growth mechanism will be reported separately. [21]

The Effect of Stabilizer Density on Transformation of CdTe Nanoparticles Induced by Ag Cations

“…[12] Our and other groups have reported that zero-dimensional (0D) NPs spontaneously transformed into one-dimensional (1D), [13][14][15][16] two-dimensional (2D), [17] three-dimensional (3D), [18] or even more complex structures [19] due to a decrease of the stabilizer's surface density on the NPs. Likewise, metalic, [20] semiconductor, [21,22] and magnetic NPs [23] were found to transform from 0D spheres to 1D or 3D nanostructures during synthesis when the amount of stabilizer was gradually decreased. However, in comparison to chemical functionalities by different types of the stabilizers, the effect of the surface density of stabilizers is much less explored, and especially their roles on the shape alteration of NPs are not clearly known due to the absence of the quantitative analysis results.…”

Superparamagnetic Magnetite Colloidal Nanocrystal Clusters

“…The fact that primary particles crystallographically align with adjacent ones can be understood as the result of oriented attachment and subsequent high-temperature sintering during synthesis. [6] Figure 2 b, c shows the secondary structures of CNCs of much larger size. The selected-area electron diffraction (SAED) pattern recorded on an isolated cluster about 174 nm in size reveals single-crystal-like diffraction (Figure 2 d).…”

“…This trend is evidenced by a number of interesting works published in the past two years. [6][7][8][9][10] Manipulation of the secondary structures of nanocrystals is desired in order to combine the ability to harness the size-dependent properties of individual nanocrystals with the possibility to tune collective properties due to interactions between the subunits. Herein we report the synthesis of highly water dispersible magnetite (Fe 3 O 4 ) colloidal nanocrystal clusters (CNCs) with uniform size from about 30 to about 180 nm, each of which is composed of many single magnetite crystallites approximately 10 nm in size.…”

Polyol‐Mediated Synthesis of Highly Water‐Soluble ZnO Colloidal Nanocrystal Clusters

“…[1][2][3][4][5] This research trend has been evidenced by plenty of interesting works published in the past several years. [6][7][8][9][10][11] Manipulation of the secondary structures of nanocrystals leads to fine-tuned interactions between the submits and enhances the possibility to tune collective properties eventually. As one of the group II-VI semiconductors, ZnO has attracted increasing attention recently owing to its nontoxicity and chemical stability towards air, especially in its diverse optoelectronic applications.…”