A Mechanochemical Route for ZnS Nanocrystals, and Batch Sorting along Size Distribution

Pengfei Hu,Chen Xie,Zhihui Mao,Xue Liang

doi:10.3390/nano9091325

Abstract

The assistances of sodium dodecyl benzene sulfonate (SDBS) and aging treatment were introduced to further improve the room-temperature mechanochemical synthesis of the quantum-sized zinc sulfide (ZnS) nanocrystals. As a result, a green strategy for synthesizing the monodisperse nanocrystals with tunable size and crystallinity was developed, holding convenient, highly efficient and low pollution. Size evolution shows a gradually increasing trend along the aging-temperature. A model that the independent reaction cells constructed by SDBS-wrapped reactant packages (solid state vesicles, SSVs) for the confined growth of ZnS nanocrystals was proposed to access the formation mechanism of ZnS quantized crystal in a solid-state synthesis system. The band gaps and band-edge luminescent emissions of as-prepared ZnS nanocrystals experienced the size-dependent quantum confinement effect, while the trap-state emissions exhibited the lattice integrity-dependence. Furthermore, ZnS quantum-sized nanocrystals with narrower size distribution can be obtained by a batch-sorting process through adjusting the centrifugal speed.

Highlights

The study for the quantized semiconductor structures was lastingly set off owing to their fascinating size, and shape-dependent electronic and optical properties, such as how the band gap of a semiconductor nanostructure increases as the particle size decreases when the dimension of nanocrystallites approach the exciton Bohr radius, due to the quantum-size confinement effect [1,2,3]
In the present room-temperature solid-state reaction system, we proposed that sodium dodecyl benzene sulfonate (SDBS) plays the role of dispersant and stabilizer like in the liquid-phase reaction system
The zigzag twinning structure and slight agglomeration in sample Q-zinc sulfide (ZnS)-Imay be due to some SDBS-wrapped packages being broken in the higher temperature. This leads to interface contact and fusion of ZnS nanocrystals, resulting in the dislocation and aggregation

Summary

Introduction

The study for the quantized semiconductor structures was lastingly set off owing to their fascinating size-, and shape-dependent electronic and optical properties, such as how the band gap of a semiconductor nanostructure increases as the particle size decreases when the dimension of nanocrystallites approach the exciton Bohr radius, due to the quantum-size confinement effect [1,2,3]. As a dispersing or stabilizing agent, SDBS can disperse reactants or stabilize products, regulating the reaction process or reducing the agglomeration of product particles. This is one of the main starting points for the use of SDBS in the synthesis of nanomaterials in a liquid phase system. The multidimensional effects of SDBS on solid-state nanosynthesis, including dispersion, stability and ligands, were proposed and discussed This strategy expands the room-temperature mechanochemical synthesis methodology for the preparation of nanocrystals

Experimental

Optical Properties of ZnS Nanocrystals

Batch-Sorting of ZnS Nanocrystals

Conclusions