Orchid Leaf-like Nickel/Aluminum Layered Double Hydroxide
Xiaoyan Liu, Jiuyang Wu, Mingshu Xiao, Xiaocai Liang, Yuqing Miao*
University of Shanghai for Science and Technology, Shanghai 200093, China
*Corresponding Author E-mail: yqmiao@usst.edu.cn
ABSTRACT:
The nickel/aluminum layered double hydroxides (Ni/Al LDHs) was synthesized by a simple co-precipitation and hydrothermal method. Heating the reactants of Ni(NO3)2, Al(NO3)3, Na3PO4 and NaOH improves the crystallinity of LDHs, leading to the formation of the orchid leaf-like Ni/Al LDHs with the width of around 100 nm and the length of around 800 nm.
1. INTRODUCTION:
Over the past decade, nanomaterials have been the subject of enormous interest1,2. These materials, notable for their extremely small feature size and extraordinary performances, have the potential for wide-ranging applications such as biotechnology, medicine, energy, information and communication, as well as scientific tools, electronics, industrial manufacturing processes, chemistry and environment, etc. Layered double hydroxides (LDHs) belong to the family of natural anionic clays like kaolinite. They comprise an unusual class of layered materials with positively charged layers and weakly bound, often exchangeable, charge-balancing anions located in the interlayer region, which are commonly represented by the formula [M2+1-xM3+x (OH)2]q+(Xn-)q/n·yH2O3. Most commonly, M2+ = Ca2+, Mg2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+ or Zn2+; Xn- = Cl-, Br-, NO3-, CO32-, SO42- or SeO42-. Due to their remarkable features such as the layered structure, large surface area, permanent layer positive charge, good thermal stability and water resistant structure, anion exchange properties and capacity to intercalate anions, LDHs are of great interest for nano materials science and technology, exhibiting potential applications in various fields including catalysis, pharmaceuticals, anion exchangers, adsorbents, precursors to oxides, magnetics, and electrodes for rechargeable alkaline batteries or analytical sensors4-6. Among various LDHs, Ni/Al LDH appears to be the most promising electroactive material for many electrochemical applications due to their good stability and electrochemical performances 7-9.
These materials are usually prepared by the common methods such as coprecipitation, hydrothermal or electrochemical reactions. In this study, we have reported the synthesis and crystallization of Ni/Al LDHs in agitated hydrothermal conditions. Heating the reactants including Ni(NO3)2, Al(NO3)3, Na3PO4 and NaOH in a pressurized aqueous media improves the crystallinity of the resultant LDHs and the orchid leaf-like Ni/Al LDHs were obtained.
2. EXPERIMENTAL:
2.1 Reagents:
Ni(NO3)2, Al(NO3)3, Na3PO4 and NaOH were purchased from Sinopharm Chemical Reagent Co. Ltd. (Shanghai, China). All other chemicals were of analytical grade and used without further purification. The deionized water of 18 MW·cm used in all the experiments was be doubly distilled and purified by a Milli-Q system (Millipore, Milford, MA). All experiments were be carried out at ambient temperature.
2.2 Preparation of the orchid leaf-like Ni/Al LDHs:
In a typical synthesis procedure, an aqueous stock solution of 50 mL containing 4.5 mM Ni(NO3)2, 4.8 mM Al(NO3)3 and 50 mM Na3PO4 were completely mixed under stirring for 30 min. The mixed solution was added dropwise with 10 mL 0.5 M NaOH under stirring. The aqueous mixture was transferred into a 100 mL Teflon-lined autoclave sealed in a stainless steel shell and was allowed to react for 2h at 160°. After cooling to room temperature, the solid products were separated by centrifugation and washed with water. The products were dried.
2.3 Characterization:
The surface morphology of the obtained orchid leaf-like Ni/Al LDHs was studied by scanning electron microscopy (SEM, S-4800 UHR FE-SEM).
3.RESULTS AND DISCUSSION:
Fig. 1 Photo of the orchid leaves and SEM images of the orchid leaf-like Ni/Al LDHs.
When NaOH was added into the solution of Ni(NO3)2, Al(NO3)3 and Na3PO4, a lightly green precipitate was observed due to the hydroxylation of Ni and Al salts. The aqueous mixture was transferred into a Teflon-lined autoclave sealed in a stainless steel shell and was allowed to react for 2h in a pressurized and heated aqueous media. After centrifugated, washed and dried, the obtained products are lightly green powders. The SEM was employed to characterize the surface morphology of products. As shown in Fig. 1, the obtained Ni/Al LDHs look like the orchid leaf of flat strip. The orchid leaf-like Ni/Al LDHs have the width of around 100 nm and the length of around 800 nm. Obviously, heating the reactants of Ni(NO3)2, Al(NO3)3, Na3PO4 and NaOH improves the crystallinity of the resultant LDHs, leading to the formation of the orchid leaf-like Ni/Al LDHs.
4. CONCLUSIONS:
A hydrothermal synthesis was employed to prepare Ni/Al LDHs by allowing the reactants of Ni(NO3)2, Al(NO3)3, Na3PO4 and NaOH to react in a pressurized and heated aqueous media. The orchid leaf-like Ni/Al LDHs were obtained.
5. REFERENCES:
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2 P. Tong, J.-Q. Gao, B.-S. Wang, W.-L. Cao, Energy. Res. Inform. 18, 138, (2002)
3 A.B. Béléké, E. Higuchi, H. Inoue, M. Mizuhata, J. Power Sources 225, 215, (2013)
4 V. Rives, M. del Arco, C. Martín, Appl. Clay Sci. 88–89, 239, (2014)
8 H. Abdolmohammad-Zadeh, S. Kohansal, G.H. Sadeghi, Talanta 84, 368, (2011)
9 M.E. Pérez-Bernal, R.J. Ruano-Casero, F. Benito, V. Rives, J. Solid State Chem. 182, 1593, (2009)
Received on 25.09.2014 Modified on 01.10.2014
Accepted on 07.10.2014 © AJRC All right reserved
Asian J. Research Chem. 7(12): December, 2014; Page 1065-1066