SI22337A - Synthesis of nanowires based on copper(i) oxide by reduction in diol without addition of water - Google Patents

Abstract

The subject of invention is a synthesis of nanowires of copper(I) oxide in diol according to a polyol procedure without addition of water. The invention comprises the procedure itself and the prepared Cu2O powder produced by this procedure. The procedure of synthesis of nanowires of copper(I) oxide takes place in diol according to the polyol procedure without addition of water, where the reduction of Cu(II) acetate to Cu2O occurs in di(ethylene glycol) with di(ethylene glycol) serving as a medium and a source of reducing agent. The prepared Cu2O powder consists of particles in the form of nanowires or nanotapes with a length of 2-10 micrometres and a diameter of 5-100 nm and their organized structures, i.e. bundles, cones and small balls, having a layer of diol and its decomposition products on the surface to protect the material from oxidation, enable its better dispersing in organic media and make the Cu2O powder oxidation resistant at the room temperature for more than one year as well as in nitrogen atmosphere up to 200 degrees Celsius.

Description

Synthesis of Copper (I) Oxide Nanoparticles with Diol Reduction without Addition of Water

The object of the invention is the synthesis of copper (I) oxide nanoparticles in a diol by a polyol process without the addition of water. The invention encompasses the process itself and the prepared Cu? O nanowires made by this process.

Copper (I) oxide (CU2O) is a p-type semiconductor and therefore has potential applications in semiconductor technology, solar panels and batteries. CU2O is a promising material for low-cost solar cells due to its high optical absorption coefficient, low electron gap and non-toxicity, which is described in the literature under serial numbers 1-4. Submicron CU2O is a potential material for negative electrodes in lithium batteries, as described in the literature under order number 5. It is used for photocatalytic degradation of organic and inorganic compounds in the visible spectral range, e.g. for photochemical degradation of water. It is also used as a catalyst in the chemical refining and synthesis of various organic compounds, which is described in the literature under order number 6. Therefore, the preparation of high quality, monodisperse CU2O nanostructures is of great importance for the chemical and electronics industries.

In recent years, research has focused on one-dimensional nanostructures materials not only for basic research but also for their use in nanotechnology. The nanoscale nanoscale nanosized semiconductors used in the nanoscale have interesting physical properties, making them useful in optoelectronics as light-emitting devices with very low power consumption. One-dimensional (ID) nanostructures are of great scientific and practical importance because of the unique combination of electronic, optical and mechanical properties. Various synthetic methods are used to prepare ID nanostructures such as carbon nanotubes, inorganic nanotubes / rods and nanotubes.

A review of the existing patent literature from 1990 onwards revealed a large number of patents in the synthesis of copper (I) oxide (CU2O) of different shapes, particle sizes, and with different reduction processes or with different reducing agents used in aqueous medium. The patented synthetic processes are hydrometallurgical reduction (W02005083132), aerosol decomposition

-2 (US5861136, SG34371, JP8319116), Electrolysis (GB191514310, CN1556250, SU1787942, SU1663050), Incineration (PL276329), UV irradiation (CN1190042), and various chemical precipitation processes (JP2003165725, JP2001211531519257253257253257257257257253257253257253257253257257257257257257257253) ). Non-defined Cu ₂ O nanoparticles were already prepared in di (ethylene glycol) (JP20044155622), and Cu ₂ O IDs were already synthesized by wet chemical method in aqueous medium and reduced with hydrazine (CN1384055). For Cu ₂ O nanowires prepared by reduction in aqueous medium (CN1384055), the authors do not provide any data on the oxidation stability of these products, nor is there any data on the adsorption of organic compounds on the surface and thus their dispersibility in organic media.

In the scientific literature cited in points 1 to 5, the indications given in the preparation of Cu ₂ O nanoparticles of different structures, but they were Cu ₂ O nanowires prepared only in an aqueous medium using hydrazine as the reducing agent, which is extremely toxic, which is described in the literature under no. 6. The cars do not provide direct data on the oxidation stability of these structures. The vacuum drying process and the large amount of oxygen adsorbed on the surface, however, indicate that these Cu ₂ O nanowires are unstable in air. Cars do not provide any information about their dispersibility in organic media.

Literature:

1. Yin M., Wu C.K., Burda C.Koberstein J.T., Zhu Y., O'Brien S., JACS 2005.127, 95069511.

2. Yu Y „Du E.P., Yu Y.C„ Zhang Υ.Υ., Wong P.K., Solid State Chem. 2004,177,46404647.

3. Snoke, D., Coherent Exciton Waves, Science, 1996, 273, 1351-1352.

4. Chen, Υ.Τ. & Zhang, W. & Zhou, B.Z. & Xu, X.Q. & Fan, Y.Q. & Guo, Y.J. &

Zhang, ZX, Polyol Process for Large-scale Synthesis of Cu ₂ O with Disk-like Structure, Chinese Chem. Letters, 2005, 16 (2), 245-248.

5. Poizot, P. et al., Nano-sized Transition-Metal Oxides for Lithium-Ion Batteries,

Nature, 2000, 407, 496-499.

6. Wang W. Et al., Synthesis and Characterization of Cu ₂ O Nanowires by a Novel Reduction Route, Adv. Mat, 2002, 14 (1), 67-69.

-3Description of the invention

The invention will be described by way of embodiments and illustrations showing:

Figure 1: IR spectrum of Cu ₂ O nanoparticles (conc. Cu acetate = 0.03 mol / l),

Figure 2: XRD diagram of Cu ₂ O nanoparticles (Cu acetate concn. = 0.03 mol / l),

Figure 3: SEM micrograph of Cu ₂ O nanoparticles (conc. Cu acetate = 0.03 mol / l),

Figure 4: SEM micrograph of Cu ₂ O nanoparticles organized into a dendritic sphere-shaped structure (conc. Cu acetate = 0.03 mol / l),

Figure 5: SEM micrograph of Cu ₂ O nanoparticles organized into 10-20 pm diameter beads (Cu acetate conc. - 0.03 mol / l),

Figure 6: Results of TGA measurements of Cu ₂ O nanoparticles in N ₂ atmosphere,

Figure 7: IR spectrum of the sample immediately after preparation (a) and IR spectrum of the sample after 18 months in air at room temperature (b),

Figure 8: SEM micrograph of nanosheets organized into a dendritic sphere-shaped structure (conc. Cu acetate = 0.06 mol / l),

Figure 9: SEM micrograph of nanoparticles forming beads 10-20 pm in diameter (conc. Cu acetate = 0.06 mol / l).

The invention describes a process for the synthesis of copper (I) oxide (Cu ₂ O) with a defined structure in the form of nanowires of 2-10 pm in length and 5-100 nm in diameter and their organized structures: bundles, cones and beads of copper compounds from the group: Cu (II) carbonate, Cu (II) acetate, Cu (II) acetyl acetonate, Cu (II) oxide, Cu (II) hydroxide, Cu (II) nitrate, Cu (II) chloride, in the diol of the group: ethylene glycol, di (ethylene glycol), tetra (ethylene glycol), 1,2-propane diol, 1,3-propane diol, glycerol, without water and with a layer of diol and its degradation products on the surface, which protects the material from oxidation and makes it easier dispersion in organic media. The essence of the synthesis process is to mix and heat the starting compound in the diol, which is both a medium and a reducing agent source that reduces Cu ²⁺ to Cu ⁺ . Reducent is a decomposition product of a diol that is not precisely chemically defined. Most likely, these are different types of aldehydes that are oxidized to carboxylic acids or ultimately to CO ₂ .

The process of synthesis of nanowires comprises:

-41. Dissolving copper compounds from the group: Cu (II) carbonate, Cu (II) acetate, Cu (II) acetyl acetonate, Cu (II) oxide, Cu (II) hydroxide, Cu (II) nitrate, Cu (II) chloride, as starting compounds in the diol of the group: ethylene glycol, di (ethylene glycol), tetra (ethylene glycol), 1,2-propane diol, 1,3-propane diol, glycerol, by ultrasound in a concentration range from 0.005 to 0.5 mol / 1

2. Stirring and heating the solution for 3 to 10 hours at a temperature of 100 ° C to 300 ° C

3. Isolation of the product by centrifugation and purification of the product by washing with ethanol and centrifugation at 1000 - 10000 rpm. from 10 min. to 2 p.m.

4. Air drying.

Advantages over the current state of the art:

- Single-step synthesis of Cu ₂ O nanoparticles with defined structure in the form of nanoparticles of 2 - 10 pm in length and 5-100 nm in diameter and their organized structures (bundles, cones and beads) in organic medium (diol) without the use of hydrazine. Due to the low toxicity and low vapor pressure of diols, this process is very environmentally friendly and environmentally friendly.

The oxidation stability of Cu ₂ O nanoparticles up to 200 ° C in nitrogen and air at room temperature for at least one year makes it easy to store and use. The organophilic surface of the nanowires makes it easier to interfere with various organic matrices (eg polymers), thereby facilitating the preparation of polymer nanocomposites. Cu ₂ O polymer matrix composites are useful for low-cost solar cells and Li-batteries.

- The large specific surface area of Cu ₂ O nanoparticles and their organized structures is an advantage in the field of catalysis, since the efficiency of catalysts depends on the specific surface area.

Example 1:

A solution of copper (II) acetate in di (ethylene glycol) at a concentration of 1x10 ' ² mol / dm ^{3 is} prepared by stirring and sonicating for 20 min at room temperature in an ultrasonic bath. Transfer the solution to a reactor equipped with an agitator, a reflux condenser, an oil bath with a contact thermometer and a resistance thermometer to measure the temperature in the reactor. The set temperature on the oil bath contact thermometer is 190 ° C. The solution was heated at a rate of 6-8 ° C / min to the set temperature and then kept constant. The color of the solution

-5 changes from initial blue green to brown green. After 6 hours and 40 minutes of heating, turn off the heat and pour the product into a beaker. Allow the suspension to stand overnight for the product to settle. If the product does not settle, centrifuge for at least 2000 rpm for several hours. Remove the solvent and wash twice with 150 ml of 98% ethanol each. The sediment was suspended in ethanol and allowed to settle overnight. It was then centrifuged for 10 min. up to 2 hours at a minimum of 1000 rpm and separate the liquid phase from the sediment. The precipitate is air dried.

Example 2:

Prepare a solution of copper (II) acetate in di (ethylene glycol) at a concentration of 4x10 ' ² mol / dm ³ by stirring and sonicating for 20 min at room temperature in an ultrasonic bath. Transfer the solution to a reactor equipped with an agitator, a reflux condenser, an oil bath with a contact thermometer and a resistance thermometer to change the temperature in the reactor. The set temperature on the oil bath contact thermometer is 190 ° C. The solution was heated at a rate of 6-8 ° C / min to the set temperature and then kept constant. The color of the solution changes from the original blue-green to brown-green. After 6 hours of heating, turn off the heat and pour the product into a beaker. The suspension is allowed to stand overnight for the product to settle. If the product does not settle, centrifuge for at least 2000 rpm for several hours. The solvent was then removed and washed twice with 150 ml of 98% ethanol each. The sediment was suspended in ethanol and allowed to settle overnight. Centrifuge for 10 min. up to 2 hours at a minimum of 1000 rpm and separate the liquid phase from the sediment. The precipitate is air dried.

The embodiments do not essentially limit the invention but merely explain it.

The result of the process according to the invention is a Cu ₂ O powder consisting of nanoparticles or nanotubes particles of 2-10 pm in length and 5-100 nm in diameter and their organized structures, i.e. bundles, cones and beads, and with a layer of diol and its degradation products on the surface, which protects the material from oxidation and makes it easier to disperse in organic media. The Cu ₂ O powder thus prepared is oxidation-resistant at room temperature for more than one year and up to 200 ° C under a nitrogen atmosphere.

-6 For a successful transfer to the industry, several conditions must be fulfilled, the most important of which are: a) price attractiveness, b) the possibility of synthesis or preparation in large quantities, and c) the environmental acceptability of the entire synthetic process. According to the invention, one-dimensional Cu ₂ O nanostructures have been prepared and their organized structures such as bundles, cones and dendritic spheres prepared by a simple diol reduction process without the use of surfactants. Cu ₂ O nanowires are stable up to 200 ° C under nitrogen atmosphere Figure 6 - and at least one year in air at room temperature - Figure 7a and 7b. On the surface, they have a protective layer of diol, which makes it easier to mix with organic matrices and thus easier to prepare polymer nanocomposites - Figure 1. Cu ₂ O nanowires, and especially their organized dendritic structures - Figures 3 and 4 - have an extremely large specific surface, which is very important for use in the field of catalysis.

Product characterization

The IR spectrum of Cu ₂ O nanoparticles according to Example 1 of Figure 1 shows an intense absorption band at 630 cm &^lt; ^-1 &^gt;, which is characteristic of Cu2O. The spectrum contains less intense bands at 1054 and 1101 cm &^lt; ^-1 &^gt;, indicating that the sample also contains residues of organic medium (di (ethylene glycol) or ethylene glycol) most likely adsorbed on the surface. The XRD spectrum of a sample of Cu2O nanoparticles shows characteristic peaks for Cu ₂ O at 20 values: 36.4; 42.4; 61.5; 73,6 - according to Figure 2. On SEM micrographs of Cu ₂ O samples prepared according to Example 1, we see Cu ₂ O particles in the form of nanowires or nanotubes with a length of 2 - 10 pm and a width of 5-100 nm - in Fig. 3 organized in bundles, cones and beads of 10-20 pm in size - according to Figures 4 and 5. The TGA curve of the Cu ₂ O nanoparticles sample shows that the structures are thermally stable at least up to 200 ° C in a nitrogen atmosphere - Figure 6. Comparison of IR spectra of the same Cu ₂ sample About nanoparticles immediately after preparation Figure 7a - and after 18 months in air at room temperature - Figure 7b - shows that these structures are quite stable at room temperature and oxidation air. SEM micrographs of Cu ₂ O nanoparticles with a concentration of starting compound = 0.06 mo 1/1 show similar structures to those of copper (II) acetate 0.03 mol / l - according to Figures 8 and 9.

Claims (5)

Claims A process for the synthesis of copper (I) oxide nanowires, characterized in that the precursor reduction, which is a copper compound in the concentration range from 0.005 to 0.5 mol / l in the group: Cu (II) carbonate, Cu (II) acetate, Cu (II) acetyl acetonate, Cu (II) oxide, Cu (II) hydroxide, Cu (II) nitrate, Cu (II) chloride, to CU2O are in the diol of the group: ethylene glycol, di (ethylene glycol), tetra ( ethylene glycol), 1,2-propane diol, 1,3-propane diol, glycerol, without the addition of water in the temperature range from 100 to 300 ° C, with the diol serving as a medium and as a reducing agent. Process according to claim 1, characterized in that the dissolution of copper (II) acetate in solvent di (ethylene glycol) is carried out in a concentration range from 0.005 to 0.5 mol / l by means of ultrasound. Process according to claim 1, characterized in that the solution is stirred and heated for 3 to 10 hours at a temperature of 160 ° C to 190 ° C. Method according to claim 1, characterized in that the product isolation is carried out by centrifugation and purification of the product by washing with ethanol and centrifuging for 10 to 2 hours at 1000 - 10000 rpm and for the product to be dried by the process. 5. Powder CU2O, characterized in that it is prepared by the process according to claims 1 to 4, comprising particles in the form of nanowires or nanotubes 2-10 pm in length and 5 100 nm in diameter and their organized structures, i.e. bundles, cones and beads and a layer of diol and its degradation products on the surface, which protects the material from oxidation and facilitates dispersion in organic media, and that the CU2O powder is oxidation-resistant at room temperature for more than one year and in a nitrogen atmosphere up to 200 ° C.