Synthesis of size‐tunable zinc blende ZnS nanocrystals

Abstract

Quasi‐polyhedral ZnS nanocrystals with monodisperse tunable sizes of 40, 52, 62, 73, 82, 94, 103, and 110 nm have been synthesized in aqueous solution by regulating the amounts of thioacetamide, zinc acetate, and acetic acid added. The mixture was heated to 120°C in an oven for 10–20 min to produce the nanocrystals. Structural characterization reveals the formation of cubic zinc blende ZnS with some polycrystallinity, which possibly influences their optical properties, that is, the measured band gaps do not give a continuous narrowing trend with increasing particle size. However, when particle sizes are expressed in terms of volumes, the absorption band positions show steady red shifts with increasing crystal dimensions and very small wavelength changes for nanocrystals beyond 90 nm. Thus, these ZnS nanocrystals still possess some size‐dependent optical properties despite their polycrystalline nature.

Size-Tunable Cu3Se2 Nanocubes Possessing Surface Plasmon Resonance Properties for Photothermal Applications

“…Since hydroxyl groups are formed in the product side, addition of NaOH also limits the crystal growth rate, enabling the formation of Cu 3 Se 2 nanocrystals with shape control. Such a strategy has also been employed to make Ag 2 O and PbS crystals with morphology evolution. , ZnS synthesis also used acetic acid to achieve adjustable particle sizes …”

“…27,28 ZnS synthesis also used acetic acid to achieve adjustable particle sizes. 29 Figure 1 shows the SEM images of the synthesized Cu 3 Se 2 nanocubes. The particles are fairly uniform with average edge lengths of 35, 46, 52, 67, and 86 nm and relative standard deviations of 14, 15, 13, 10, and 13%, respectively.…”

Semiconductor nanocrystals possessing broadly size‐ and facet‐dependent optical properties

“…[42] Quasi-spherical ZnS nanoparticles with tunable sizes of 40-110 nm also show size-dependent light absorption behavior. [43] PbS nanocubes with edge lengths of 13-121 nm display progressive red-shifts in absorption feature with increasing nanocube sizes. [44] For large SrTiO 3 cubes with edge lengths of 160-290 nm, slight absorption band shifts are still observable.…”

Origin and manifestation of semiconductor facet effects

“…[64] With respect to the optical size effect, diverse semiconductor nanocrystals including Ag 3 PO 4 , SrTiO 3 , PbSe, ZnS, CeO 2 , Cu 3 Se 2 , CdS, CdSe and CuI have been shown to display such optical behavior, so this is the general optical property of semiconductor crystals. [7,37,[65][66][67][68][69][70][71][72] As particle size increases from below 10 nm to tens of nanometers and well over 100 nm, their absorption bands red-shift progressively, so band gaps actually decrease gradually. For larger particles with sizes beyond 100 nm, band gap can still shift but the extent can be quite small.…”