CN104016408A - Synthetic method of sodium niobate nanowire - Google Patents

Abstract

The invention discloses a method for synthesizing sodium niobate nanowires, which includes the steps of mixing NaOH with an organic solvent, the steps of hydrothermal reaction, the steps of washing and centrifugal separation, and the steps of drying. The equipment used in the method of the invention is simple, The reaction conditions are mild, without the preparation of mesophase precursors and post-annealing treatment; the reaction raw materials are cheap, and no expensive surfactants are used as templates; the process is simple, energy saving, low cost, easy to operate and control, and good repeatability. The main features of being convenient for industrialized production can effectively shorten the synthesis time and improve production efficiency, and it is an ideal green synthesis process.

Description

A kind of synthetic method of sodium niobate nanowire

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technical field

The invention relates to a solvothermal synthesis method of sodium niobate nanowires, in particular to a method for repeatedly synthesizing sodium niobate nanowires in one step, and belongs to the field of alkali metal niobate nanometer functional materials.

Background technique

Sodium niobate is an important inorganic non-metallic functional material with a typical perovskite structure, because of its good nonlinear optics, ferroelectricity, piezoelectricity, photocatalysis and pyroelectricity, etc. , has great application potential in the fields of energy recovery, smart sensing, energy conversion, and photocatalysis, and has attracted great attention in the fields of scientific research and technical applications. [W. Zeng, X. M. Tao, S. Chen, S. M. Shang, H. L. W. Chan, S. H. Choy, Energy Environ. Sci., 2013, 6, 2631-2638; M. Blomqvist, S. Khartsev, A. Grishin, A. Petraru , C. Buchal, Appl. Phys. Lett., 2003, 82, 439.] The microstructure of a material, including particle size, morphology and distribution, plays a decisive role in its performance. Due to interfacial and size effects, low-dimensional nanosized functional materials exhibit significant performance enhancements. In particular, the piezoelectric and photocatalytic properties of one-dimensional sodium niobate nanopowders (including nanowires, nanofibers, nanorods, etc.) have obvious advantages over other morphologies (nanoblocks, nanospheres, etc.). [J. Lv, T. Kako, Z. S. Li, Z. G. Zou, J. H. Ye, J. Phys. Chem. C, 2010, 114, 6157–6162; T. Y. Ke, H. A. Chen, H. S. Sheu, J. W. Yeh, H. N. Lin, C. Y. Lee, H. T. Chiu, J. Phys. Chem. C, 2008, 112, 8827–8831.] So far, the synthesis of one-dimensional sodium niobate powder mainly includes molten salt method, electrospinning method and hydrothermal method. Xu used the molten salt method to first prepare K ₂ Nb ₈ O ₂₁ nanowire templates, and then performed ion exchange under molten salt conditions to obtain sodium niobate nanowires. The process is cumbersome, consumes a lot of energy, and has certain risks; [C. Y. Xu, L. Zhen, R. Yang, Z. L. Wang, J. Am. Chem. Soc., 2007, 129, 15444–15445.] Electrospinning can prepare sodium niobate with uniform size and controllable size Nanowires, but need to rely on expensive equipment, the production efficiency is extremely low, which is not conducive to industrialization; [W. Zeng, X. M. Tao, S. Chen, S. M. Shang, H. L. W. Chan, S. H. Choy, Energy Environ. , 2631-2638.] At present, the hydrothermal method plus post-annealing treatment is commonly used to prepare sodium niobate nanowires, that is, the one-dimensional intermediate The product Na ₇ (H ₃ O)Nb ₆ O ₁₉ ^. 14H ₂ O or Na ₂ Nb ₂ O ₆ is then annealed to obtain sodium niobate nanowires. [J. H. Jung, C. Y. Chen, W. W. Wu, J. I. Hong, B. K. Yun, Y. S. Zhou, N. Lee, W. Jo, L. J. Chen, L. J. Chou, Z. L. Wang, J. Phys. Chem. C, 2012, 116 (42) , 22261–22265.] The preparation of sodium niobate nanowires by the hydrothermal method has obvious advantages over the molten salt method, but the one-dimensional intermediate product is very sensitive to the reaction environment, the reaction conditions need to be precisely controlled, and the post-calcination treatment is also required. The energy consumption is large and the process is complicated. Therefore, it is of great significance to realize the one-step synthesis of sodium niobate nanowires by using simple equipment and simple process methods for the application of sodium niobate in the fields of energy conversion and photocatalysis.

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Contents of the invention

technical problem

The technical problem to be solved in the present invention is to provide a one-step solvothermal synthesis method that realizes sodium niobate nanowire powder efficiently and quickly. The sodium niobate nanowire powder prepared by this method has excellent photocatalytic performance and piezoelectricity. performance.

Technical solutions

In order to solve the above-mentioned technical problems, the synthetic method of sodium niobate nanowire of the present invention comprises the following steps:

Step 1: Add NaOH powder in an organic solvent such as ethylene glycol at a concentration ratio of 0.5~1.0mol/L, heat and stir for 20~30min to obtain a mixed solution of NaOH and organic solvent; Add 0.5~1.5g raw material Nb ₂ O ₅ into the solution, heat and stir for 15~20min to make it evenly mixed to form a milky white mixed solution; among them, the ratio of the amount of NaOH to Nb ₂ O ₅ should be greater than 1;

Step 2: Transfer the mixed solution obtained in Step 1 to the polytetrafluoroethylene lining, then place the lining in a stainless steel hydrothermal reaction kettle and seal it, and perform a heat preservation reaction at 120~200°C for 4~16h. After the reaction is completed, Cool naturally to room temperature to obtain white precipitate;

Step 3: Use deionized water and absolute ethanol to wash and centrifuge the white precipitated product multiple times, at a speed of 1000-3000 rpm, for 5-30 minutes, to wash away all the remaining ions and organic solvents;

Step 4: drying at 50-80° C. for 12-24 hours to obtain sodium niobate nanowire powder.

In the technical solution of the present invention, NaOH should be firstly added into the ethylene glycol solvent for stirring treatment, so as to dissolve or mix it as uniformly as possible, so that the size uniformity of NaNbO ₃ nanowires can be effectively controlled.

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Beneficial effect

The method of the present invention uses simple equipment, mild reaction conditions, no need for preparation of mesophase precursors and post-annealing treatment; low price of reaction raw materials, no need for expensive surfactants as templates; simple process flow, energy saving, low cost, and easy Operation and control, good repeatability, easy industrial production and other main features can effectively shorten the synthesis time and improve production efficiency. It is an ideal green synthesis process. Compared with prior art, the beneficial effect that the inventive method has is:

(1) Using the complete organic solvent ethylene glycol as the reaction medium to realize the one-step solvothermal synthesis of sodium niobate nanowires, the process is simple, the synthesis efficiency is high, and it is convenient for industrial production;

(2) The required NaOH concentration is 0.5~2mol/L, the reaction temperature is 120~200℃, the reaction conditions are mild, the energy consumption is low, and the safety is high;

(3) The selectivity and adjustability of the obtained sodium niobate nanowires are strong, the concentration of NaOH is 0.5~2.0mol/L, the content of Nb ₂ O ₅ is 0.5~1.5g, and the reaction time is 4~16h. Sodium acid nanowires;

(4) As shown in the maps and photos of Figure 1, Figure 2, and Figure 3, the size of the obtained sodium niobate nanowires is smaller (10~20nm), the size distribution range is narrow, and the reaction repeatability is good.

The sodium niobate nanowires synthesized by the invention have small size, narrow distribution and certain selectivity. This convenient and efficient synthesis method of sodium niobate nanowires is bound to create new opportunities and impetus for the industrial production of sodium niobate materials and their applications in the fields of energy conversion and photocatalysis.

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Description of drawings

Figure 1 is the XRD pattern of _NaNbO3 obtained by solvothermal reaction at 140°C for 8 hours;

Figure 2 is a field emission scanning electron microscope (FE-SEM) photo of NaNbO ₃ nanowires obtained by solvothermal reaction at 180°C for 8 hours;

Figure 3 is the size distribution diagram of NaNbO ₃ nanowires obtained by solvothermal reaction at 200 ° C for 4 h, and the inset is a transmission electron microscope (TEM) photo.

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Detailed ways

The present invention will be specifically described below in conjunction with specific examples, but the present invention is by no means limited to the implementations described in the examples. All the one-dimensional nanometer powders of sodium niobate synthesized by solvothermal method, and all the deformations directly derived or associated from the content disclosed in the present invention should be considered as the scope of protection of the present invention.

Embodiment one

Add 1.6664g NaOH to 50ml of ethylene glycol solvent, heat and stir for 20~30min; after it is fully mixed, continue to add 1.5g of raw material Nb ₂ O ₅ , heat and stir for 15~20min to make it evenly mixed to form a milky white mixed solution . The resulting mixed solution was transferred to a polytetrafluoroethylene lining, and then the lining was placed in a stainless steel hydrothermal reaction kettle to seal it, and the reaction was carried out at 140°C for 8 hours, and naturally cooled to room temperature after the reaction was completed. Use deionized water and absolute ethanol to wash and centrifuge the white precipitated product multiple times at a speed of 3000 rpm for 10 minutes to ensure that all residual ions and organic solvents are washed away; dry at 60°C for 24 hours , to obtain sodium niobate (NaNbO ₃ ) nanowire powder.

Embodiment two

Add 1.6664g NaOH into 50ml of ethylene glycol solvent, heat and stir for 20~30min; after it is fully mixed, continue to add 1.0g of raw material Nb ₂ O ₅ , heat and stir for 15~20min, make it evenly mixed, and form a milky white mixed solution . The resulting mixed solution was transferred to a polytetrafluoroethylene lining, and then the lining was placed in a stainless steel hydrothermal reaction kettle to seal it, and the reaction was carried out at 180°C for 8 hours. After the reaction was completed, it was naturally cooled to room temperature. Use deionized water and absolute ethanol to wash and centrifuge the white precipitated product several times at a speed of 3000rpm for 10min to ensure that all residual ions and organic solvents are completely washed out; After drying for 24 hours, sodium niobate (NaNbO ₃ ) nanowire powder was obtained.

Embodiment three

Add 3.3328g NaOH into 50ml of ethylene glycol solvent, heat and stir for 20~30min; after it is fully mixed, continue to add 0.5g of raw material Nb ₂ O ₅ , heat and stir for 15~20min, make it evenly mixed, and form a milky white mixed solution . The resulting mixed solution was transferred to a polytetrafluoroethylene lining, and then the lining was placed in a stainless steel hydrothermal reaction kettle to seal it, and the reaction was carried out at 200°C for 4 hours, and naturally cooled to room temperature after the reaction was completed. Use deionized water and absolute ethanol to wash and centrifuge the white precipitated product several times at a speed of 3000rpm for 10min to ensure that all residual ions and organic solvents are completely washed out; After drying for 24 hours, sodium niobate (NaNbO3) nanowire powder was obtained.

Claims (3)

1. onethe synthetic method of planting sodium niobate nano line, is characterized in that, comprises the following steps:

Step 1: add NaOH powder according to the concentration ratio of 0.5 ~ 1.0mol/L in organic solvent, heat and stir 20 ~ 30min and obtain the mixing solutions of NaOH and organic solvent; After it fully mixes, in above-mentioned mixing solutions, add 0.5 ~ 1.5g raw material Nb ₂o ₅, heated and stirred 15 ~ 20min, evenly mixes it, forms milky mixing solutions;

Step 2: the mixing solutions of step 1 gained is transferred in polytetrafluoroethyllining lining, then liner is positioned in stainless steel hydrothermal reaction kettle and is sealed, carry out 4 ~ 16h insulation reaction at 120 ~ 200 DEG C, after question response finishes, naturally cool to room temperature and obtain white depositions;

Step 3: adopt respectively deionized water and dehydrated alcohol repeatedly to wash and centrifugation gained white precipitate product, rotating speed is 1000 ~ 3000rpm, and the time is 5 ~ 30min, all washes remaining ion and organic solvent to the greatest extent;

Step 4: carry out drying and processing under 50 ~ 80 DEG C of conditions, the time is 12 ~ 24h, obtains sodium niobate nano line powder.

2. a kind of synthetic method of sodium niobate nano line as described in claim 1, is characterized in that: the organic solvents such as selected reaction solvent is ethylene glycol.

3. a kind of synthetic method of sodium niobate nano line as described in claim 1, is characterized in that: ensure NaOH and Nb ₂o ₅the ratio of amount of substance be greater than 1, temperature of reaction is 120 ~ 200 DEG C, the reaction times is 4 ~ 16h.