Elsevier

Materials Letters

Volume 63, Issue 5, 28 February 2009, Pages 512-514
Materials Letters

Synthesis and characterization of SnSe2 hexagonal nanoflakes

https://doi.org/10.1016/j.matlet.2008.10.054Get rights and content

Abstract

Single phase SnSe2 was synthesized at 180 °C by hydrothermal co-reduction method from SnCl2·2H2O== and SeO2, its morphology and growth direction were investigated. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM). Experimental results show that, the SnSe2 powder almost consists of regular and homogenous hexagonal nanoflakes which grow along (0001) crystal plane, these nanoflakes are about 600–700 nm in side length and 30–40 nm in thickness.

Introduction

Tin selenides such as SnSe and SnSe2 have brilliant application prospects due to their excellent optical and electrical properties, which can be applied in film electrodes [1], infrared optoelectronic devices, thermoelectric refrigerators and solar cells etc [2]. Therefore there have been many research works about tin selenides in recent past, such as nanocrystalline SnSe synthesized by Qian's group from aqueous solution [3], [4], SnSe nanowires prepared via an ethylenediamine-assisted polyol route [5], plate like and rod like orthorhombic SnSe crystals grown by an organic solution method [6], nanocrystalline photoconducting SnSe thin films with quantum dots prepared by a chemical bath deposition method [7], Sn–Se compounds on a gold electrode fabricated by electrochemical atomic layer epitaxy [8], SnSe single crystals grown by a direct vapour transport technique [9] and nanocrystalline tin selenides synthesized by electron beam irradiation method [10]. The petal-like nanoflakes and irregular sheet-like SnSe2 have been synthesized via the solvothermal route [11]. While hexagonal nanoflakes of SnSe2 were successfully synthesized by hydrothermal method in this work.

Section snippets

Experimental details

For preparing SnSe2, 0.002 mol SnCl2·2H2O and 0.004 mol SeO2 were added into a stainless steel autoclave with a Teflon liner of 20 mL capacity. The autoclave was filled with deionized water up to 80% of the total volume. After ultrasonic agitation for about 30 min, 2 mL hydrazine hydrate (N2H4·H2O) was poured into the reactants. The autoclave was sealed and heated at temperature 180 °C for 24 h in an electric furnace. After heating, it was cooled down to room temperature naturally. The black

Synthesis of SnSe2 by hydrothermal co-reduction

Fig. 1 shows the XRD pattern of the product prepared by hydrothermal co-reduction method at 180 °C. It shows that the major phase in the product is SnSe2.

The reaction mechanism is proposed as follows: When all the reactants are put into the autoclave and heated, Sn2+ and Se4+ are easily reduced by hydrogen decomposed from N2H4, because their positive electrode potential are much higher than hydrogen. The as-reduced Sn atoms and Se atoms are very active and can easily combine to be SnSe

Conclusions

Single phase SnSe2 was synthesized at 180 °C by hydrothermal co-reduction method from SnCl2·2H2O and SeO2. The SnSe2 powder almost consists of regular and homogenous hexagonal nanoflakes which grow along the (0001) crystal plane, these nanoflakes are about 600–700 nm in side length and 30–40 nm in thickness.

Acknowledgement

This work was supported by the Shandong excellent middle-aged and Young scientist encourage and reward foundation (No. 2007BS04017).

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