CN106976901A - CeO (CeO)2Method for synthesizing nanobelt - Google Patents

Abstract

CeO (CeO)₂The synthesis method of the nanobelt comprises the steps of dissolving cerous nitrate and 1, 3-phthalic acid in a mixed solvent of absolute ethyl alcohol and water to obtain Ce (NO) with the concentration of 0.02mol/L₃)₃Putting the mixed solution into a reaction kettle, synthesizing a cerium coordination polymer precursor by a mixed solvothermal method, and preparing quasi-one-dimensional CeO by simple calcination₂The nanobelt does not need to be added with a surfactant or alkali liquor, so that the influence of the dropping speed of the alkali liquor on the appearance of the material is avoided, and the synthesis method is simple and efficient.

Description

A kind of synthetic method of CeO2 nanobelt

technical field

The present invention relates to a kind of synthetic method of nanometer material, specifically, relate to a kind of synthetic method of CeO2 _nanobelt especially.

Background technique

Due to their unique physical and chemical properties, rare earth coordination polymers have shown good potential application value in light, electricity, magnetism, catalysis, gas storage, etc., so they have attracted the attention of researchers. At present, research centers in this field mainly Focus on synthesizing coordination polymers with unique structures by simple and novel methods. Its special coordination mode and crystal structure are very likely to make materials have special properties, thereby expanding the application space of materials. In the research of various rare earth materials Among them, the preparation and application of rare earth oxides have always been the focus of research. It is also one of the focuses of current research to control the properties and applications of rare earth oxides by adjusting their morphology and size. The preparation of rare earth oxides with diverse morphology rare earth coordination polymers as precursors can be better achieved. For this purpose, the rare earth oxides synthesized by simple calcination of rare earth coordination polymers generally have the advantages of porous structure and larger specific surface, so they also have more excellent properties, all of which indicate that coordination polymers are the preparation However, it is still a great challenge to synthesize rare earth metal oxides with ultralong nanoribbon structures by this method.

Cerium dioxide is a typical light rare earth oxide, which has been widely used in ultraviolet absorbers and shielding agents, catalysts, photoelectric materials, luminescent materials, polishing agents, and advanced ceramics. Nano-scale ceria materials It has excellent oxygen storage and release functions and high-temperature rapid oxygen vacancy diffusion ability, so it is widely used in oxidation-reduction reactions, used in catalysts, fuel cells, gas sensors, anti-corrosion coatings, polishing and abrasive materials, etc., because cerium has Variation, so its oxides have unique redox properties, which have attracted more and more attention. Among them, one-dimensional ceria nanomaterials, such as nanowires/nanofibers, nanorods, nanobelts, nanotubes, etc., exhibit Therefore, the preparation of one-dimensional ceria nanomaterials has been one of the research hotspots. The preparation methods of one-dimensional ceria nanomaterials mainly include: metal organic chemistry Vapor deposition method, chemical vapor deposition method, soft and hard template method, ultrasonic method, electrospinning method, solvothermal/hydrothermal method, etc., for example: [Chemistry of Materials, 2001,13(12):4402-4404] Hexafluoro-2,4-pentanedione and diglyme and cerium compound as precursors, one-dimensional CeO ₂ nanometers grown along the (110) plane on nickel alloy substrates by metal-organic chemical vapor deposition Material, document [Thinsolid films,1999,347:25-30] is raw material with the cerium salt of 2-hexyl-1,3 hexanediol, and toluene is solvent, uses chemical vapor deposition method under 1000 ℃ in sapphire (α- Al ₂ O ₃ ) substrates grow one-dimensional CeO ₂ nanomaterials, the literature [J MaterSci,2005,40,1305-1307] uses C ₁₈ H ₃₇ NH ₂ as a soft template, according to 1.0Ce(NO ₃ ) ₃ : 10.0HNO ₃ : 2.0C ₁₈ H ₃₇ NH ₂ Mixed and stirred at 80°C for 24 hours, then slowly added concentrated ammonia water dropwise at this temperature for 6 hours and continued to stir for 8 hours to obtain single crystal CeO ₂ nanowires, literature [Mater Res Bull, 2004,39,1023-1028] with cerous nitrate and urea as raw materials, anodized aluminum oxide film (AAM) as a hard template prepared CeO2 nanowire arrays, literature [J Cryst Growth, _{2005,281,525-529} ] through simple Sonication, the transformation of _CeO2 spherical nanoparticles into _CeO2 nanotubes in alkaline solution. The literature [Thin SolidFilms, 2005, 478, 228-231] uses electrospinning technology to prepare Ce(NO ₃ ) ₃ /PVP nanofibers, and obtains CeO ₂ nanofibers after calcination. The literature [RSC Adv, 2015, 5, 37585-37591] is the same The Ce(NO ₃ ) ₃ /PVP nanofiber precursor was obtained by electrospinning technology, and then two different CeO ₂ nanomaterials were obtained by controlling the calcination conditions. One-step calcination directly raised the temperature to 550°C at a heating rate of 5°C/min Keep it for 3 hours to get CeO ₂ nanobelts, and two-step calcination, first raise the temperature to 300 ℃ at a rate of 5 ℃/min, and then raise the temperature to 550 ℃ at a rate of 15 ℃/min and keep it for 3 hours to get CeO ₂ nanobelts. Compared with these two CeO ₂ nanomaterials, the latter ie CeO ₂ nanotubes are more active after loading Au. Literature [InorgChem, 2009, 48, 1334-1338] used Ce(OH)CO ₃ nanorods as precursors, without using any template, and obtained different one-dimensional CeO ₂ nanotubes only by changing the conditions of lye treatment of the precursors /rod/wire, 1. Ce(OH)CO ₃ nanorods were treated with alkaline solution at room temperature for several days, and then acid-washed to obtain polycrystalline CeO ₂ nanotubes (T -type); 2. It is also treated with lye at room temperature for several days, but then roasted to obtain polycrystalline CeO2 nanotubes (K _- type) that are basically similar to T-type, but its formation mechanism is similar to that of T-type Different, increasing the lye treatment temperature or lye concentration, is to obtain solid CeO ₂ nanorods/wires; 3. Treating with dilute lye at 120°C for 24 hours can obtain small-sized, single-ended nanorods/wires with open ends. Crystalline CeO ₂ nanotubes (L-type), the above-mentioned CeO ₂ nanotubes were used for CO oxidation, and the catalytic performance was higher than that of commercially available CeO ₂ . The preparation method of -type single crystal CeO ₂ nanotubes is fine-tuned, the amount of precursor Ce(OH)CO ₃ and the concentration of alkali solution are increased, and CeO ₂ single crystal nanotubes with more regular morphology and higher yield can be obtained after hydrothermal treatment Tube, used for photocatalytic degradation of benzene vapor in the atmosphere, the catalytic performance is higher than that of CeO ₂ nanoparticles and TiO ₂ (P25), the author also used its loaded palladium for the selective catalytic oxidation of benzyl alcohol to benzaldehyde, the results showed that, Because it can prevent palladium aggregation, its activity is higher than that of palladium/commercially available CeO ₂ [Chinese Journal of Catalysis, 2013,34,1123-1127], literature [CrystEngComm,2011,13,1786-1788] compares cerium nitrate and m-benzene Diformic acid solution is mixed at room temperature, and then ammonia water is added dropwise to adjust the acidity and alkalinity of the solution to be neutral, so that cerium-based coordination polymer nanowires with high aspect ratio can be obtained, and CeO2 nanowires can be obtained after roasting. _The characteristics of this method are It can be synthesized at room temperature, the aspect ratio of the precursor nanowire is high, and the yield is high, but the speed of ammonia water dripping has a great influence on the morphology of the product.

In summary, it is not easy to prepare one _- dimensional CeO2 nanomaterials by the liquid phase method, because the cubic _CeO2 has no intrinsic driving force to form an anisotropic macrostructure, so it is usually necessary to use surfactants or The template acts as a directing agent for the synthesis of anisotropic structures, or requires high-concentration lye hydrothermal or solvothermal treatment to obtain highly anisotropic CeO ₂ .

The above one-dimensional CeO ₂ synthetic methods of nanomaterials, some methods (such as hard template method, chemical vapor deposition method, etc.) have loaded down with trivial details steps, synthetic efficiency is low, what have also needs to use poisonous and harmful organic solvent; Spinning method) requires special equipment; and most of the methods need to be synthesized in alkaline medium, and there is a problem that the lye drop speed affects the product morphology, or high-concentration lye hydrothermal or solvothermal treatment is required to obtain highly anisotropic CeO ₂ .

Contents of the invention

The object of the present invention is to provide a kind of synthetic method of _CeO2nanobelt , synthesize cerium coordination polymer precursor by the method for mixed solvothermal, prepare quasi-one-dimensional _CeO2nanobelt by simple calcining, do not need to add Surfactant, does not need to add lye, avoids the influence of lye drop speed on the shape of the material, the synthesis method is simple and efficient, and has better advantages than the above methods,

Under the condition of high temperature and high pressure, the ultra-long nanoribbon material of cerium-based coordination polymer was synthesized by mixed solvothermal method, and then CeO ₂ with ultra-long nanoribbon structure was prepared by simple one-step calcination. The width of the cerium-based coordination polymer was 50 to 200 nanometers, 20 to 40 nanometers in thickness, tens of microns in length, the cerium coordination polymer is converted into CeO ₂ after roasting, the shape is somewhat curled and cohesive, but basically maintains the nanoribbon structure of the precursor. At present, people pass Template method, or alkali treatment to synthesize rare earth oxide materials with one-dimensional nanostructure, and the present invention successfully prepared cerium-based oxide materials with quasi-one-dimensional structure by using a new simple template-free, alkali-free solvothermal method Coordination polymer ultra _- long nanobelts can be calcined to obtain CeO2 materials with nanobelt structure, the method is simple, and the operation is easy to control.

The concrete realization steps of the present invention are as follows:

Step 1: dissolving cerium nitrate and 1,3-phthalic acid in a mixed solvent of absolute ethanol and water to obtain a Ce(NO ₃ ) ₃ solution with a concentration of 0.02mol/L;

Step 2: Put the above mixed solution in a reaction kettle, react at 160°C for 24 hours, centrifuge and wash after the reaction, and dry at 60°C to obtain a cerium coordination polymer nanoribbon material;

Step 3: Place the dried sample obtained above in a muffle furnace, calcinate at 400-500° C. for 4 hours, and cool to room temperature to obtain a CeO ₂ material with a nanoribbon structure.

The present invention adopts template-free and alkali-free method to synthesize the CeO2 material with ultra _- long nanoribbon structure, synthesized under high temperature and high pressure airtight conditions, without surfactant, without adding lye, and avoiding the influence of lye drop speed on the shape. The synthesis steps are simple, and the solvents used are relatively cheap and non-toxic absolute ethanol and water.

The invention adopts the alcohol-water mixed solvothermal method to synthesize the precursor. Due to the closed environment of high temperature and high pressure, the coordination polymer nanoribbon structure of cerium can be formed under the condition of no template and no alkali, and the synthesized precursor is uniform and difficult to agglomerate.

The present invention uses 1,3-benzenedicarboxylic acid as an organic linker through the selection of raw material formula, mainly because 1,1,3-benzenedicarboxylic acid is an aromatic carboxylic acid ligand, a rigid ligand, and a hard base , and rare earth ions belong to hard acids, so the two are more firmly combined and the structure is relatively easier to control; 2. Studies have shown that whether it is a normal temperature precipitation method or a solvothermal method, 1,3-phthalic acid is easy to form with cerium nitrate salt Coordination polymers with one-dimensional structure; 3, 1,3-phthalic acid can be fully deprotonated or partially deprotonated, and can have a variety of acidity coordination modes. Acid deprotonation can be achieved with alkali, It can also be realized in high-temperature ethanol. High temperature is more conducive to the dissociation of protons from acid, and the ability of ethanol to bind protons is stronger than that of water. Just based on this, the present invention does not use alkali, but uses alcohol-water (mainly alcohol) mixed solvents The acid was deprotonated by thermal method, and then combined with cerium nitrate to form a cerium-based coordination polymer precursor.

The present invention needs to go through solvothermal and simple heat treatment process, the oven reaction temperature is 160°C, the reaction time is 24h, and the calcination temperature in the muffle furnace is 400-500°C, and the calcination time is 4h.

The technical effect of the invention is: the precursor of the cerium coordination polymer is synthesized by the mixed solvothermal method, the quasi-one _- dimensional CeO2 nanobelt is prepared by simple calcination, no need to add surfactant, no need to add lye, and avoid alkali The effect of droplet velocity on the morphology of materials, and the synthesis method is simple and efficient.

Description of drawings

Fig. 1 is the XRD pattern of the cerium coordination polymer (a) and CeO ₂ (b) nanomaterials with the nanoribbon structure of the present invention.

Fig. 2 is the scanning electron microscope image of the cerium coordination polymer (a) and CeO ₂ (b) nanomaterials with the nanoribbon structure of the present invention.

detailed description

The beneficial effects of the present invention will be described in detail below in conjunction with the embodiments of the accompanying drawings, aiming at helping readers better understand the essence of the present invention, but not limiting the implementation and protection scope of the present invention.

Referring to Fig. 1, the XRD diffraction pattern is measured with a D8ADVANCE polycrystalline X-ray diffractometer (CuKα radiation, ), the scanning electron microscope pictures were obtained on a Japanese HITACHIS-3400N scanning electron microscope with an accelerating voltage of 15kV.

With reference to Fig. 1, Fig. 1 is the XRD pattern of the cerium coordination polymer (a) of nanoribbon structure and CeO ₂ (b) nanomaterials, as can be seen from the figure, the cerium coordination polymer of superlong nanoribbon structure after firing All the peaks of the sample are completely consistent with the standard card of cubic CeO ₂ (JCPDS 34-0394), indicating that the coordination polymer after calcination is completely converted into CeO ₂ , and the final product is determined to be high-purity ceria.

Referring to Figure 2, the SEM images of nanoribbon-structured cerium coordination polymers (a) and CeO ₂ (b) nanomaterials, from Figure 2 (a, b) we can see that the synthesis of ultra-long nanoribbon-structured cerium coordination polymers, The width is 50-200 nanometers, the thickness is 20-40 nanometers, and the length is tens of microns. Figure 2(c,d) shows that the nanoribbon structure of the precursor is basically maintained after the cerium coordination polymer is fired, with some curling and adhesion.

Example 1:

Step 1: Dissolve 2.0mmol Ce(NO ₃ ) ₃ ·6H ₂ O cerium nitrate and 4.0mmol 1,3-phthalic acid in a mixed solvent of 75mL absolute ethanol and 25mL water;

Step 2: Put the above mixed solution in a reaction kettle, react at 160° C. for 24 hours, centrifuge wash after the reaction, and dry at 60° C. to obtain a nanoribbon material of a cerium coordination polymer;

Step 3: Place the dried sample obtained above in a muffle furnace, calcinate at 400° C. for 4 hours, and cool to room temperature to obtain a CeO ₂ nanomaterial with a nanoribbon structure.

Example 2:

Step 1: Dissolve 2.0mmol Ce(NO ₃ ) ₃ ·6H ₂ O cerium nitrate and 3.0mmol 1,3-phthalic acid in a mixed solvent of 75mL absolute ethanol and 25mL water;

Step 2: Put the above mixed solution in a reaction kettle, react at 120°C for 12h, centrifuge and wash after reaction, and dry at 60°C to obtain a cerium coordination polymer nanoribbon material;

Step 3: Place the dried sample obtained above in a muffle furnace for calcination at 400° C. for 4 hours, and cool to room temperature to obtain a CeO ₂ nanomaterial with a nanoribbon structure.

The above-mentioned embodiments are only descriptions of preferred implementations of the present invention, and are not intended to limit the scope of the present invention. Variations and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (2)

1. a kind of CeO₂The synthetic method of nanobelt, it is characterised in that step one：Cerous nitrate, 1,3- phthalic acids are dissolved in anhydrous The in the mixed solvent of second alcohol and water, obtains the Ce (NO that concentration is 0.02mol/L₃)₃Solution；Step 2：Above-mentioned mixed solution is placed in In reactor, centrifuge washing after 24h, reaction is reacted under the conditions of 160 DEG C, 60 DEG C are dried to obtain cerium coordination polymer nanometer band Material；Step 3：Drying sample obtained above is placed in Muffle furnace, 4h is calcined at 400-500 DEG C, is cooled to after room temperature and obtains CeO₂Nanobelt material.

2. a kind of CeO according to claim 1₂The synthetic method of nanobelt, it is characterised in that with cerous nitrate, 1,3- benzene two Formic acid is raw material, and absolute ethyl alcohol and water are mixed solvent, and first reaction obtains cerium coordination polymer nanobelt material in a kettle., Then the CeO of nanometer band structure is obtained in the calcining of Muffle furnace high temperature₂Material.