Preparation method, application and freezing liquid of nano cuprous oxide cubic single crystal
The 40nm cuprous oxide cube single crystal is prepared by reacting copper salt, sodium dodecyl sulfate and alkali with a reducing agent at room temperature and dispersing it into the frozen liquid, which solves the difficulty in preparing small-sized oxidation sub-substances in the prior art. The problem of copper single crystals has significantly improved the heat transfer efficiency and freezing efficiency of the frozen liquid.
Patent Information
- Application Number
- CN202210425985.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-04-21
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2042-04-21
AI Technical Summary
It is difficult to prepare copper oxide nanocrystals below 50 nm, especially single crystal materials, which leads to the failure to effectively improve their heat transfer efficiency in the refrigerant.
By reacting the copper salt, sodium dodecyl sulfate and alkali with a reducing agent at room temperature, a 40nm cuprous oxide cube single crystal was prepared and dispersed into the frozen liquid, using a simple and low-cost method.
It has achieved effective improvement of heat transfer efficiency in the refrigerant, significantly improved the freezing efficiency, and the preparation process is simple, green and low cost.
Smart Images
Figure CN114908413B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of nanocrystal preparation, and in particular to a preparation method, application and freezing liquid of a nano cuprous oxide cubic single crystal. Background Art
[0002] Refrigeration technology plays an important role in house temperature regulation, food transportation, food preservation, etc., and provides strong technical support for the living standards of the people. Among them, refrigerant is the core carrier of refrigeration technology. Through the heat conduction of refrigerant, the temperature of the working environment drops rapidly to achieve the purpose of refrigeration. In recent years, studies have shown that dispersing nanomaterials into liquids to form nanofluids can significantly improve the heat transfer performance of liquids, making the application of nanofluids in the field of heat transfer widely concerned. Generally speaking, nanofluids can improve the overall heat transfer performance through their own high thermal conductivity, Brownian motion of nanoparticles, and interface layers on the surface of nanoparticles. Nanoparticles themselves conduct heat through electronic conduction and lattice vibration, which is closely related to Brownian motion and the size of nanoparticles. Brownian motion can be effectively improved by reducing the size, and the internal defects of particles can be reduced by single crystals with good crystallinity, so that the conduction efficiency of electrons and phonons is improved, thereby further improving the heat conduction efficiency. At present, the application of nanofluids in refrigerants is still in the preliminary research stage. In particular, there are relatively few reports on copper-based metal oxide nanomaterials as research objects.
[0003] Cuprous oxide (Cu2O) is a P-type semiconductor metal oxide material with the characteristics of abundant raw material resources and low price. Cuprous oxide has unique catalytic, gas sensing, photocatalytic and thermal conductivity properties, and its application in energy, chemical engineering, optoelectronic devices, biomedicine and other fields has attracted widespread attention. So far, cuprous oxide nanomaterials are mainly prepared by precipitation, hydrothermal, solvothermal and other synthesis methods, which usually require heating conditions or the use of strong reducing agents (hydrazine hydrate, etc.) to reduce copper salts. For example, a cuprous oxide concave octahedral structure of about 2μm was prepared using glucose as a reducing agent in a 60°C hot water bath (Wang, X.; Liu, C.; Zheng, B.; Jiang, Y.; Zhang, L.; Xie, Z.; Zheng, LJ Mater. Chem. A, 2013, 1, 282). However, most of the reported cuprous oxide sizes are hundreds of nanometers or even micrometers, and there are relatively few reports below 100nm. Therefore, the preparation of single-crystal cuprous oxide nanocrystals below 100 nm, especially below 50 nm, can significantly enhance the Brownian motion of the particles, which is beneficial to improving the stability and heat transfer efficiency of cuprous oxide nanofluids, and is of great significance. Summary of the invention
[0004] The object of the present invention is to provide a preparation method, application and freezing liquid of nano cuprous oxide cubic single crystal, which can prepare cuprous oxide cubic single crystal with a size of 40nm, and the preparation method is simple and low in cost.
[0005] To achieve the above object, the present invention discloses a method for preparing nano cuprous oxide cubic single crystals, which comprises the following steps:
[0006] S1: Dissolve copper salt and sodium dodecyl sulfate in ultrapure water and stir well.
[0007] S2: Add an aqueous solution of alkali to react.
[0008] S3: Add reducing agent aqueous solution to react.
[0009] S4: Separate and clean the reaction product of step S3 to obtain 40 nm cuprous oxide cubic single crystals.
[0010] Wherein, the mass ratio of the copper salt, sodium dodecyl sulfate, alkali and reducing agent is 40-90:0-215:16-28:30-45.
[0011] Preferably, the mass ratio of the copper salt, sodium dodecyl sulfate, alkali and reducing agent is 85:72:18:35.
[0012] Preferably, the copper salt is one of copper chloride, copper acetate and copper sulfate.
[0013] Preferably, the alkali is one of sodium hydroxide, potassium hydroxide and ammonia water; the reducing agent is one of ascorbic acid and citric acid.
[0014] Preferably, in step S1, the dissolution of the copper salt and sodium dodecyl sulfate is accelerated by ultrasound; after the copper salt and sodium dodecyl sulfate are completely dissolved, stirring is performed at a rotation speed of 500 to 800 rpm for 10 to 60 minutes.
[0015] Preferably, the reaction time of step S2 is controlled within 5 to 30 min, and the stirring is performed at a rotation speed of 500 to 800 rpm during the reaction.
[0016] Preferably, the reaction time of step S3 is controlled within 5 to 20 min, and the stirring is performed at a rotation speed of 500 to 800 rpm during the reaction.
[0017] Preferably, in step S4, the reaction product of step S3 is separated by a centrifuge, the rotation speed of the centrifuge is controlled at 10000-15000 rpm, and the separated product is washed with ultrapure water and anhydrous ethanol for 2-5 times respectively.
[0018] The present invention also discloses an application of nano-cubic cuprous oxide single crystals, which uses the nano-cubic cuprous oxide single crystals prepared by any of the above-mentioned methods for preparing nano-cubic cuprous oxide single crystals in nano-refrigerating liquids.
[0019] In addition, the present invention also discloses a freezing liquid, which comprises a nano-cubic cuprous oxide single crystal prepared by the method for preparing a nano-cubic cuprous oxide single crystal as described in any one of the above items, wherein the nano-cubic cuprous oxide single crystal accounts for 1×10 of the total volume fraction of the freezing liquid. -5 ~2×10 -4 .
[0020] The present invention has the following beneficial effects:
[0021] The present invention can prepare 40nm cuprous oxide cubic single crystals, and compared with the existing precipitation method, hydrothermal method, and solvent thermal method preparation process, it has the characteristics of simplicity, greenness, and low cost. The 40nm cuprous oxide cubic single crystals prepared by the method of the present invention are dispersed and applied in the freezing liquid, which can effectively improve the heat transfer efficiency of the freezing liquid, thereby improving the freezing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a transmission electron microscope image of the 40nm cuprous oxide cubic single crystal obtained in Example 1.
[0023] Figure 2 This is a statistical distribution diagram of the particle size of the 40 nm cuprous oxide cubic single crystal obtained in Example 1.
[0024] Figure 3 This is the X-ray powder diffraction pattern of the 40 nm cuprous oxide cubic single crystal obtained in Example 1.
[0025] Figure 4 This is one of the high-resolution transmission electron micrographs of the 40nm cuprous oxide cubic single crystal obtained in Example 1.
[0026] Figure 5 This is the second high-resolution transmission electron micrograph of the 40 nm cuprous oxide cubic single crystal obtained in Example 1.
[0027] Figure 6 This is the third high-resolution transmission electron micrograph of the 40 nm cuprous oxide cubic single crystal obtained in Example 1.
[0028] Figure 7 This is the selected area electron diffraction pattern of the 40 nm cuprous oxide cubic single crystal obtained in Example 1.
[0029] Figure 8 This is a scanning transmission electron microscope image of the 40nm cuprous oxide cubic single crystal obtained in Example 1.
[0030] Fig. 9 This is the Cu element surface scan of the X-ray energy dispersion spectrum of the 40 nm cuprous oxide cubic single crystal obtained in Example 1.
[0031] Fig.10 This is an X-ray energy dispersion spectrum O element surface scan of the 40nm cuprous oxide cubic single crystal obtained in Example 1.
[0032] Fig.11 This is a picture of the frozen liquid prepared from the 40nm cuprous oxide cubic single crystal obtained in Example 1 after being left to stand for 0 hours.
[0033] Fig.12 This is a picture of the frozen liquid prepared from the 40 nm cuprous oxide cubic single crystal obtained in Example 1 after being left to stand for 4 hours.
[0034] Fig.13 This is a comparison chart of the cooling efficiency of the freezing liquid (marked by black dots) prepared from the 40 nm cuprous oxide cubic single crystal obtained in Example 1 and the freezing liquid blank sample (marked by black squares).
[0035] Fig.14 This is a transmission electron microscope image of the 40nm cuprous oxide cubic single crystal obtained in Example 2.
[0036] Fig.15 This is a transmission electron microscope image of the 40nm cuprous oxide cubic single crystal obtained in Example 3.
[0037] Fig.16 This is a transmission electron microscope image of the 40nm cuprous oxide cubic single crystal obtained in Example 4.
[0038] Fig.17 This is a transmission electron microscope image of the 40nm cuprous oxide cubic single crystal obtained in Example 5.
[0039] Fig.18 This is a transmission electron microscope image of the 40nm cuprous oxide cubic single crystal obtained in Example 6. DETAILED DESCRIPTION
[0040] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.
[0041] like Figures 1 to 5As shown, the present invention discloses a method for preparing a nano-cubic cuprous oxide single crystal, and the raw materials used include: copper salt, sodium dodecyl sulfate, alkali, reducing agent, ultrapure water and anhydrous ethanol, wherein the mass ratio of copper salt, sodium dodecyl sulfate, alkali and reducing agent is 40-90:0-215:16-28:30-45, and preferably, the mass ratio of copper salt, sodium dodecyl sulfate, alkali and reducing agent is 85:72:18:35. Ultrapure water is mainly used for dissolving raw materials and cleaning. When dissolving, it is sufficient to ensure that it is not too diluted, and there is no need to specify the dosage; anhydrous ethanol is used for cleaning, and there is no need to specify the dosage. In addition, in the present invention, the copper salt is selected from one of copper chloride, copper acetate and copper sulfate; the alkali is selected from one of sodium hydroxide, potassium hydroxide and ammonia water; and the reducing agent is selected from one of ascorbic acid and citric acid. The raw materials listed above are all commonly used raw materials in the chemical industry, easy to purchase, and the cost of raw materials is relatively low.
[0042] The preparation method specifically comprises the following steps:
[0043] S0: weigh the raw materials according to the above mass ratio for later use. The alkali can be prepared into an alkali aqueous solution in advance, or it can be prepared at the end of step S1.
[0044] S1: Dissolve copper salt and sodium dodecyl sulfate with ultrapure water and stir evenly. Put the weighed copper salt and sodium dodecyl sulfate into a glass reaction bottle, add an appropriate amount of ultrapure water to dissolve. During the dissolution process, ultrasound can be used to accelerate the dissolution progress. After complete dissolution, stir at a speed of 500-800 rpm, and the stirring time is controlled at 10-60 minutes. Using ultrapure water can avoid the influence of impurities. After stirring, enter step S2.
[0045] S2: Adding an aqueous solution of alkali to react. Add an aqueous solution of alkali to the solution obtained in step S1 to react. Stir at a speed of 500 to 800 rpm during the reaction. The reaction time is controlled to be 5 to 30 minutes. When the reaction time is finished, enter step S3.
[0046] S3: Adding reducing agent aqueous solution to react. Add reducing agent aqueous solution to the reaction solution obtained in step S2 to react, stirring at a speed of 500-800 rpm during the reaction, and the reaction time is controlled to be 5-20 minutes. When the reaction time is finished, enter step S4.
[0047] S4: The reaction product of step S3 is separated by centrifuge. During the centrifuge separation process, the speed is controlled at 10000-15000rpm. The separated product is washed 2-5 times with ultrapure water and anhydrous ethanol respectively to remove the residual reactants, and a 40nm cuprous oxide cubic single crystal is obtained, which is placed in a vacuum desiccator for storage.
[0048] The above steps can be carried out directly at room temperature without heating, thus eliminating heating costs and facilitating cost control.
[0049] Based on the same inventive concept, the present invention also discloses an application of nano-cubic cuprous oxide single crystals, which uses the nano-cubic cuprous oxide single crystals prepared by the above preparation method in nano-refrigerating liquid.
[0050] Based on the same inventive concept, the present invention also discloses a freezing liquid, which contains nano-cubic cuprous oxide single crystals prepared by the above preparation method, wherein the nano-cubic cuprous oxide single crystals account for 1×10 of the total volume fraction of the freezing liquid. -5 ~2×10 -4 .
[0051] In order to verify the feasibility of the above preparation method and the properties of the product obtained by the above preparation method, copper salt, alkali and reducing agent were selected and six groups of embodiments were prepared. The proportions and selections of each embodiment are shown in Table 1. Among them, the ultrasonic treatment time of step S1 is unified as 10 minutes, the stirring speed is unified as 600 rpm, and the stirring time is 30 minutes; the stirring speed of step S2 is unified as 600 rpm, and the stirring time is 10 minutes; the reaction time of step S3 is unified as 10 minutes, and the stirring speed is unified as 600 rpm during the reaction.
[0052] Table 1
[0053]
[0054]
[0055] With respect to the above examples, the final product obtained by the above preparation method is systematically characterized by transmission electron microscopy, scanning transmission electron microscopy, X-ray selected area diffraction, X-ray energy dispersion spectrum scanning, X-ray powder diffraction and other characterization techniques for its morphology, structure, elements, composition and other information. Next, Example 1 is described in detail.
[0056] like Figure 1 As shown, the morphology of the prepared product is a cubic shape, such as Figure 2 As shown, about 70% of the product particles are between 35 and 45 nm in size, with an average particle size of 39.4 nm. Figure 3 As shown, the diffraction peaks of the product correspond well to the cuprous oxide standard PDF card 05-0667, and no other impurity peaks are found, indicating that the prepared product is pure phase cuprous oxide. Figures 4-5 As shown in Figure 2, high-resolution transmission electron microscopy can once again confirm that the product is a cubic single crystal structure, and lattice fringes can be clearly seen. Figure 6 The lattice fringes in the image show that the fringe spacing is 0.210 nm, which is close to the (200) crystal plane of cuprous oxide, indicating that the exposed crystal plane of the cube is the (100) crystal plane. Figure 5 Selected area electron diffraction of a single cuprous oxide particle in Figure 7 By observing the spectrum, we can find that there are two sets of diffraction signals, polycrystalline rings and single crystal spots. The polycrystalline rings come from the carbon film carrying cuprous oxide, and the single crystal diffraction spots come from cuprous oxide. By indexing the single crystal diffraction spots, we can find that it is indeed a simple cubic structure of cuprous oxide. Figures 4 to 7 The systematic characterization fully demonstrates that the prepared product is a cubic single crystal of cuprous oxide with the (100) crystal plane exposed. Figure 8 The SEM images in the figure again show that the product is a cubic structure; at the same time, Fig. 9 and Fig.10 The X-ray dispersion spectrum scan shows that there are a lot of Cu and O in the product, and the signals of Cu and O can be well matched with Figure 8 The samples in the SEM images overlap, again demonstrating that the product is cuprous oxide.
[0057] In order to test the stability of 40nm CuO cubic single crystal nanofluid (i.e., frozen liquid dispersed with 40nm CuO cubic single crystal), the nanofluid was left to stand for 4h (comparison Fig.11 and Fig.12 ) It can be observed that the nanofluid is still very well dispersed in the aqueous solution, and no large amount of sedimentation occurs. In order to explore the thermal conductivity of the 40nm cuprous oxide cube nanofluid prepared in Example 1, the cuprous oxide cubes were dispersed in water and a freezing solution (ethanol and water were prepared in a volume ratio of 1:1) for thermal conductivity testing. The test results show that the volume fraction is 2×10 -5 , 4×10 -5 , 8×10 -5 The thermal conductivities of 40 nm cuprous oxide cubes dispersed in water are 0.589714, 0.59532, and 0.56 W m -1 K -1 , respectively, than the thermal conductivity of water (0.536104W m -1 K -1 ) increased by 10.0%, 11.05% and 4.46%. -5 The thermal conductivity of 40nm cuprous oxide cubes dispersed in the freezing liquid is 0.395729Wm -1 K -1 , the thermal conductivity of the refrigerant (0.372075 W m -1 K -1) was increased by 6.36%. In addition, the volume fraction was further increased to 8×10 -5 40nm cuprous oxide cubes were dispersed into the freezing liquid for cooling test. Fig.13 As shown, compared with the blank sample of the freezing liquid, the freezing efficiency of the freezing liquid dispersed with cuprous oxide cubes is higher, and the time required is shorter as the temperature decreases. These fully demonstrate that the 40nm cuprous oxide cube nanofluid can well improve the heat transfer efficiency of the freezing liquid and improve the freezing efficiency.
[0058] For Example 2, the morphology and size of the product were characterized by transmission electron microscopy. Fig.14 As shown, the product is cuprous oxide cubes, and the size is mainly concentrated between 30 and 50 nm.
[0059] For Example 3, the morphology and size of the product were characterized by transmission electron microscopy. Fig.15 As shown, the product is cuprous oxide cubes, the size of which is mainly concentrated between 30 and 60 nm, and there are some cubes of 80 to 90 nm.
[0060] For Example 4, the morphology and size of the product were characterized by transmission electron microscopy. Fig.16 As shown, the product is cuprous oxide cubes, the size of which is mainly concentrated between 40 and 60 nm, but the edges of the cubes become smoother.
[0061] For Example 5, the morphology and size of the product were characterized by transmission electron microscopy. Fig.17 As shown, the product is 30-50 nm cuprous oxide cubes.
[0062] For Example 6, the morphology and size of the product were characterized by transmission electron microscopy. Fig.18 As shown, the product is cuprous oxide cubes of 20 to 80 nm.
[0063] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.
Claims
1. A method for preparing nano cuprous oxide cubic single crystals, characterized in that: The following steps are involved: S1: Dissolve copper salt and sodium dodecyl sulfate in ultrapure water and stir evenly; S2: adding an aqueous solution of alkali to react; S3: adding a reducing agent aqueous solution to react; the reducing agent is one of ascorbic acid and citric acid; S4: separating and cleaning the reaction product of step S3 to obtain a 40 nm cuprous oxide cubic single crystal; The mass ratio of the copper salt, sodium dodecyl sulfate, alkali and reducing agent is 85:72:18:35; and steps S1 to S4 are all carried out at room temperature.
2. The method for preparing nano-cuprous oxide cubic single crystal according to claim 1, characterized in that: The copper salt is one of copper chloride, copper acetate and copper sulfate.
3. The method for preparing nano cuprous oxide cubic single crystal according to claim 1, characterized in that: The alkali is one of sodium hydroxide, potassium hydroxide and ammonia water.
4. The method for preparing nano-cuprous oxide cubic single crystal according to claim 1, characterized in that: In step S1, the dissolution of the copper salt and sodium dodecyl sulfate is accelerated by ultrasound; after the copper salt and sodium dodecyl sulfate are completely dissolved, stirring is performed at a rotation speed of 500 to 800 rpm for 10 to 60 minutes.
5. The method for preparing nano-cubic cuprous oxide single crystals according to claim 1, characterized in that: The reaction time of step S2 is controlled within 5 to 30 minutes, and the stirring is performed at a rotation speed of 500 to 800 rpm during the reaction.
6. The method for preparing nano cuprous oxide cubic single crystal according to claim 1, characterized in that: The reaction time of step S3 is controlled within 5 to 20 minutes, and the stirring is performed at a rotation speed of 500 to 800 rpm during the reaction.
7. The method for preparing nano-cubic cuprous oxide single crystals according to claim 1, characterized in that: In step S4, the reaction product of step S3 is separated by a centrifuge, the rotation speed of the centrifuge is controlled at 10000-15000 rpm, and the separated product is washed with ultrapure water and anhydrous ethanol for 2-5 times respectively.