Synthesis, Optical and Structural Properties of Copper Sulfide Nanocrystals from Single Molecule Precursors.

Peter Ajibade,Nandipha Botha

doi:10.3390/nano7020032

Abstract

We report the synthesis and structural studies of copper sulfide nanocrystals from copper (II) dithiocarbamate single molecule precursors. The precursors were thermolysed in hexadecylamine (HDA) to prepare HDA-capped CuS nanocrystals. The optical properties of the nanocrystals studied using UV–visible and photoluminescence spectroscopy showed absorption band edges at 287 nm that are blue shifted, and the photoluminescence spectra show emission curves that are red-shifted with respect to the absorption band edges. These shifts are as a result of the small crystallite sizes of the nanoparticles leading to quantum size effects. The structural studies were carried out using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and atomic force microscopy. The XRD patterns indicates that the CuS nanocrystals are in hexagonal covellite crystalline phases with estimated particles sizes of 17.3–18.6 nm. The TEM images showed particles with almost spherical or rod shapes, with average crystallite sizes of 3–9.8 nm. SEM images showed morphology with ball-like microspheres on the surfaces, and EDS spectra confirmed the presence of CuS nanoparticles.

Highlights

IntroductionThe synthesis and studies of the optical and structural properties of nanomaterials expecially metal chalcogenides have received considerable attention in the last decades due to quantum confirement effects associated with their small crystallites sizes [1,2,3,4,5,6] that give them novel properties that make them useful in light-emitting diodes [7], solar cells [8], fuel cells [9], drug delivery [10,11], and as catalysts for industrial transformations [12,13,14,15,16]
Several methods have been used to synthesize metal sulfide nanoparticles, including solvothermal synthesis [32], microwave [33], ultrasonic irradiation [34], and thermolysis of single-source precursors in high boiling point solvents that act as surface passivating agents [35,36,37,38]
We report the use of three copper (II) dithiocarbamate complexes as efficient single-source precursors for the preparation of hexadecylamine (HDA)-capped copper sulfides nanoparticles

Summary

Introduction

The synthesis and studies of the optical and structural properties of nanomaterials expecially metal chalcogenides have received considerable attention in the last decades due to quantum confirement effects associated with their small crystallites sizes [1,2,3,4,5,6] that give them novel properties that make them useful in light-emitting diodes [7], solar cells [8], fuel cells [9], drug delivery [10,11], and as catalysts for industrial transformations [12,13,14,15,16]. As of result of the inherent toxicity of group 12 metal chalcogenides, copper sulfide nanocrystals are being explored for different applications [21,22,23,24,25,26,27]. For the synthesis of CuS nanocrystals, different synthetic techniques have been used [39,40,41,42] to produce nanoparticles with varying morphologies such as nanotubes [43], nanowires [44], and nanoplatelets [45], among others [46,47]. The single-source precursor technique produces nanocrystals with reasonable monodispersity [48], and studies have indicated that the sizes and shapes of the resulting nanocrystals are influenced by the precursor concentration [49], reaction

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Results

Conclusion