To inorganic nanoparticles via nanoclusters: Nonclassical nucleation and growth pathway

Abstract

Nanoclusters, intermediates in size between atoms and nanoparticles, have been a topic of great interest because of their unique molecular structures and optical properties as compared to those of nanoparticles and bulk counterparts. Recent mechanistic studies have shown that the nanoclusters appear in the initial stages of the nanoparticle growth. The formation of nanoclusters is supported by the nonclassical nucleation theory, revealing that the nanoclusters with extremely large surface areas can be stabilized by the ligands. In this review, we first provide the theoretical background of the classical and nonclassical nucleation mechanisms in the nanoparticle formation, which helps understand the stability of nanoclusters. We then focus on the synthesis and characterization of nanoclusters of noble metals, semiconductors, metal oxides, and their alloys. Furthermore, the potential applications in bioimaging, sensing, optoelectronics, and catalysis, enabled by unique optical and chemical properties of nanoclusters, are discussed.

Synthesis of single‐crystalline InP tetrapod nanocrystals via addition of ZnCl2

“…We confirmed that the added Zn precursors passivate the surface of the InP tetrapod by measuring X‐ray photoelectron spectroscopy and quantitatively analyzed the elemental composition (In, P, Cl, Zn) of the InP tetrapod NCs according to various feed ratios of ZnCl 2 to InCl 3 . (Table 1) The In/P ratio in all samples was measured around 1.2, indicating InP NCs have an In‐rich surface and this ratio is matched well with previous report 5 . The ratios of Cl/In and Zn/In were linearly (1:1) increased with higher Zn/In feed ratio, it might be passivated with the reduction form of ZnCl acting as a Z‐type ligand, which could be reduced such as aminophosphine or oleylamine.…”

“…with a bulk band gap of 1.35 eV. However, the synthesis of III–V NCs is more difficult and complicated for high quality of NCs as compared to that of II–VI NC because III–V NCs have more covalent bonding characteristics than II–VI NCs 3–8 . In this regard, controlling of surface defects is challenging in III–V NCs.…”

“…(Table 1) The In/P ratio in all samples was measured around 1.2, indicating InP NCs have an In-rich surface and this ratio is matched well with previous report. 5 The ratios of Cl/In and Zn/In were linearly (1:1) increased with higher Zn/In feed ratio, it might be passivated with the reduction form of ZnCl acting as a Z-type ligand, which could be reduced such as aminophosphine or oleylamine.…”

“…However, the synthesis of III-V NCs is more difficult and complicated for high quality of NCs as compared to that of II-VI NC because III-V NCs have more covalent bonding characteristics than II-VI NCs. [3][4][5][6][7][8] In this regard, controlling of surface defects is challenging in III-V NCs. Understanding of surface in III-V NCs is necessary to study with welldefined structure.…”

Effect of co‐substitution on complex thermoelectric compounds: The Zintl phase Ba1‐xSrxZn2‐yCuySb2 system

“…Three quaternary and quinary compounds BaZn 1.76-Cu 0.24 Sb 2 , BaZn 1.58 Cu 0.42 Sb 2 , and Ba 0.91 Sr 0.09 Zn 1.70 Cu 0.30 Sb 2 were successfully synthesized by the molten Pb-metal flux method, and their isotypic crystal structures were carefully characterized by powder X-ray diffraction (PXRD) as well as single crystal x-ray diffraction (SXRD) analyses. [13][14][15][16][17][18][19][20][21] A series of DFT calculations 16,22,23 using the tight-binding linear muffin-tin orbital (TB-LMTO) method 24 was also performed to understand their electronic structures. Moreover, the resultant density of states (DOS), crystal orbital Hamilton population (COHP) curves, and electron localization function (ELF) diagrams were also thoroughly discussed to elucidate the effect of the co-substitution using both of the Sr-and Cu-substitutions on the electrical transport property.…”