Based on the complex decomposition approach, a simple hydrothermal method has been developed for the synthesizing of Sb2S3 nanorods with high yield in 24 h at
Recently, metal chalcogenides have attracted considerable attention due to their proven and potential applications in electronic, optical, and superconductor devices. Among these materials, antimony sulfide (Sb2S3) is a kind of semiconductor with its interesting high photosensitivity and high thermoelectric power. Antimony sulfide is a layer-structured direct bandgap semiconductor with orthorhombic crystal structure [
All the reagents were of analytical grade and were used without further purification. In a typical procedure, 0.4 g CS2, 0.6 g EDTA, and 1 g NaOH were added to 50 mL distilled water and stirred well for 20 min at room temperature. Then, 1 mmol of SbCl3 was added to above mixture and the mixture was transferred into a 100 mL Teflon-lined autoclave. The autoclave was sealed a, maintained at 150°C for 24 h, and cooled at room temperature, naturally. The black precipitate was filtered and washed with dilute chloride acid and water. Then, it was dried at room temperature. Yields for the products were 96%. Finally, the obtained sample was dried at room temperature and used for characterization. The best conditions for this reaction are pH = 10, temperature 150°C, and time of reaction 24 h. Under other conditions, some impurity is seen in XRD patterns and EDS related to unreacted raw elements or formation of antimony oxides. The crystal structure of the product was characterized by X-ray diffraction (XRD D500 Simens) with CuK
A typical XRD of the as-prepared Sb2S3 is shown in Figure
XRD patterns of the Sb2S3 nanorods synthesized at 150°C for 24 h.
Figure
EDX patterns of synthesized Sb2S3 nanorods synthesized at 150°C for 24 h.
The crystal size (CS) is calculated from X-ray diffraction patterns using Scherer’s formula (
SEM images of the Sb2S3 nanorods in (a) low and (b) high magnifications synthesized at 150°C and 24 h.
Also, Figure
AFM image of Sb2S3 nanorods synthesized at 150°C for 24 h.
Figure
(a) TEM image of the Sb2S3 nanorods synthesized at 150°C and 24 h (b) HRTEM image and FFT (c) SAED of the Sb2S3 nanorods. The SAED zone axis is [111].
To explain the synthesis process, possible chemical reaction involved in the synthesis of Sb2S3 could be listed in Scheme
Possible chemical reaction in the synthesis of Sb2S3 nanorods.
First, EDTA was reacted with CS2 in water for 12 h to give a clear solution, which was precipitated in ethanol. The product was recrystallized in methanol: chlorophorm (1 : 1) mixture and characterized by FTIR spectroscopy. This is a thiocarbonate ester of EDTA, which seems to act as a ligand to form an intermediate complex of Sb3+, as confirmed by similar FTIR spectroscopy. Such an intermediate complex is isolated by heating of a reaction mixture of CS2, EDTA, NaOH, and SbCl3 in water under hydrothermal condition for 1 h. The resultant mixture was filtered and the obtained precipitate was identified by FTIR spectroscopy.
Comparison of the FTIR spectra shows that the same bands indicate some shift due to the complexation of the ligand. The line positions (in cm−1) of
(a) Excitation spectra and (b) emission spectra of Sb2S3 nanorods.
The absorption spectra of Sb2S3 (prepared by dispersion of Sb2S3 nanorods in ethanol) show an intense absorption band at 315 nm with band gap around 3.29 ev (Figure
UV/Vis spectra of Sb2S3 nanorods.
Most of the materials have different structural defects that create defect energy levels between band gaps of material. These defects result in difference of the UV absorption and PL excitation spectra.
In summary, a complex decomposition approach in hydrothermal condition has been developed to prepare Sb2S3 nanorods with high yield. The length of the nanorods is up to 6
This work is funded by the World Class University Grant KRF R32-2008-000-20082-0 of the National Research Foundation of Republic of Korea. Y. Hanifehpour thanks the Council of the University of Tabriz for their invaluable guidance.