Hydrothermal synthesis of NiO nanobelts and the effect of sodium oxalate

doi:10.1016/j.matlet.2015.04.149

Materials Letters

Volume 156, 1 October 2015, Pages 25-27

https://doi.org/10.1016/j.matlet.2015.04.149 Get rights and content

Highlights

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NiO nanobelts with uniform size and well-defined architectures were synthesized via a facile hydrothermal method.
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A novel formation mechanism of NiO nanobelts was proposed.
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The adjunction of sodium oxalate plays a key role on formation of NiO 1D architectures.
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Morphologies of NiO nanobelts can be tailored by controlling the dose of sodium oxalate.

Abstract

Nanomaterials with low-dimensional architectures frequently exhibit novel functional properties. In current work, NiO nanobelts with well-defined morphologies and uniform size have been successfully synthesized via a facile hydrothermal method. Furthermore, a novel growth mechanism of NiO nanobelts has been proposed in detail. Surprisingly, it is worth mentioning that the sodium oxalate is of great benefit to the formation of NiO one-dimensional nanostructures and plays a vital role on tailoring morphologies of nanobelts on the basis of further comparative experiments. Such a synthetic way may open up an avenue to prepare some other oxides.

Graphical abstract

In this work, we have successfully synthesized NiO nanobelts via a facile hydrothermal route and investigated the effect of sodium oxalate.

Introduction

As a significant p-type semiconductor with wide band gap energy in the range of 3.6–4.0 eV, nickel oxide (NiO) has captured a great deal of interests in varieties of application fields [1], [2], [3], such as full cell electrodes [4], solar cell [5], catalysts [6], photovoltaic devices [7] and gas sensors [8]. In the past few years, it has been acknowledged that synthesis of multifarious nanomaterials with novel morphologies has attracted massive attentions owing to their unique architectures and extensive potential applications [9], [10], [11]. Notably, one-dimensional nanostructures of metal oxide may exhibit unique functional properties, which cannot be realized in their individual nanobulks, due to the controlled motion of electron in limited dimensions, and thereby are of the great interest in current research. As is known to all, massive efforts have been developed to synthesize NiO nanomaterials with low-dimensional architectures, such as chemical precipitation [12], sol–gel method [13], ultrasonic technique [14] and hydrothermal method [15]. Compared with other synthetic techniques, hydrothermal method is one of the most effective routes due to its low cost, convenient operation, mild condition, improvement of the thermal stability and functional properties of NiO nanomaterials [16], [17], which hence applied to our experiment. Although considerable works have been carrying out to fabricate NiO one-dimensional architectures, it still remains a huge challenge to synthesize NiO nanobelts with well-defined morphologies and excellent dispersion. Moreover, it has been the first observation that transformation from NiO nanobelts (1D) to nanosheets (2D) can be triggered by reducing of the dose of sodium oxalate, indicating that sodium oxalate played a key role on the formation of the NiO nanobelts (1D), which has been systematically investigated in our work.

In current work, NiO nanobelts have been successfully synthesized via sodium oxalate assisted hydrothermal. The as-obtained powders were characterized in terms of structures and morphologies. Furthermore, a novel formation mechanism of NiO nanobelts was proposed and the effects of sodium oxalate on the growth of NiO nanobelts were investigated in detail.

Section snippets

Experimental

All the chemicals were of analytic purity and used directly without any further purification. In a typical hydrothermal procedure, 0.474 g of nickel chloride hexahydrate (NiCl₂·6H₂O) and 0.044 g sodium oxalate (Na₂C₂O₄) were dissolved in 18 ml of distilled water. And then 30 ml ethylene glycol (EG) was introduced into the breaker under vigorous stirring for 30 min. After that, the obtained solution was transferred into a Teflon-lined stainless steel autoclave (50 ml) and sealed 18 °C for 12 h in an

Results and discussion

To confirm structure and purity of the prepared precursors and final products, XRD patterns of as-prepared samples were first performed in Fig. 1(a) and (b). As illustrated in Fig. 1(a)I–III, all the diffraction peaks of the precursors can be well index to the standard spectrum (JCPDS Card no. 25-0581), indicating that these products must be the pure NiC₂O₄·2H₂O. Whereas the sheet-like samples proved to be the pure Ni(OH)₂, as illustrated in Fig. 1(a)IV. Fig. 1(b) displays the XRD patterns of

Conclusion

In this letter, NiO nanobelts with uniform size and well-defined morphologies have been successfully synthesized via a sodium oxalate assisted hydrothermal route and subsequent thermal calcination. A plausible formation mechanism of NiO nanobelts was proposed. Furthermore, the effect of sodium oxalate on the morphologies has been investigated in detail. It was amazingly found that NiO nanobelts can be more uniform and dispersed by controlling the dose of sodium oxalate, which also play a

Acknowledgments

This work was supported in part by the National Natural Science Foundation of China, China (No. 51202302, 51277185 and 11332013), the Fundamental Research Funds for the Central Universities (No. 106112015CDJXY130013), 6th Student Research Training Program of the Chongqing University, China (CQU-SRTP-2014155) and the fund of Chongqing University׳s Large-scale Equipment (No. 2013121521).

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Hydrothermal synthesis of NiO nanobelts and the effect of sodium oxalate

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Experimental

Results and discussion

Conclusion

Acknowledgments

Mater Res Bull

Electrochim Acta

Power Sources

Catal Today

Mater Lett

Physica E

Mater Lett

Mater Lett

Mater Lett

Mater Lett