CN1208500C - Method for preparing nano copper protoxide material by metal copper anodic oxidation method - Google Patents

Abstract

A copper anode is used for dissolving in a chloride medium, which is a mature flow for producing cuprous oxide (Cu2O), but the flow is only used for producing powder with a micrometer particle diameter. A growth inhibitor of Cu2O crystallization or/and a Cu2O crystallization centre, or a carrier containing a crystallization centre, or/and other nanometer materials are added in a chloride electrolyte; in electrolytic solution, the concentration of chloride salt, alkaline concentration, the electric quantity of electric energy and electrolytic temperature are controlled; therefore, Cu2O powder of which the particle diameter is less than 100 nm, nanometer Cu2O with a carrier, or nanometer composite materials, such as Cu2O carbon nanometer tubes and Cu2O nanometer titanium dioxide, can be obtained.

Description

Method for preparing nano cuprous oxide material by metal copper anodic oxidation method

Technical Field

The present invention belongs to a method for preparing nano cuprous oxide with photocatalysis function

Background

Cuprous oxide (Cu)₂O) is a visible light catalyst, can be widely applied to solar cells, wastewater treatment, gas purification, sterilization, deodorization, pesticides, ship antifouling paint and the like, and is also a catalyst commonly used in the petrochemical industry. As the photocatalyst, there are advantages in that visible light in sunlight can be utilized, and there is a disadvantage in that recombination rate of generated electrons and holes is high, thus being higher than that of titanium dioxide (TiO)₂) The utilization rate of light energy is low. To overcome the disadvantage of low efficiency, the surface area of the photocatalyst must be increased, one of the ways is to add Cu₂O is deposited on glass fibers or porous materials (appl. surf. Sci.174: 177 (2001); J. Elecrochem. Soc.147 (2): 486(2000)), and its most thorough method should be to prepare nano-Cu₂And (3) O material.

So far, no commercial nano Cu exists₂O appears, and the preparation of nano Cu is not found₂O. Preparation of nano Cu published in various periodicals₂The physical methods of O are: plasma evaporation (Thin solid films.213: 226 (1992); appl. Phys. Lett.79: 3176(2001)), microwave irradiation (chemical world. 2000, 12: 632), chemical vapor deposition (Sol. Mater. Sol.cell.5: 85 (1998); adv.Mater.7: 562(1995)), gamma-ray irradiation (Mater. Res. Bull.29: 277(1994)), ultraviolet irradiation (Medit. 33: 330 (1997)). However, these physical methods are mostly costly or not easily industrialized. The mechanical milling methods commonly used for the preparation of nanomaterials have not been successful because monovalent copper ions are catalytically oxidized to divalent copper ions by mechanical forces during the ball milling process (mater.sci.forum.1999: 312). The sol-gel method which is also commonly used only produces Cu₂Report on O colloidal solution (scientific report: 38: 1609 (1993); Angew. chem. int. Ed. 40: 359(2001)), Cu in wet state₂O is highly susceptible to oxidation during the separation process. Reduction of copper salts with glucose by covering with polyvinylpyrrolidone (PVP)By using the method, 10-50nm Cu can be prepared₂O(J.Colloid Int.Sci.214：95(1973))。

Electrochemical method for preparing nano Cu₂O is possible. Anodic oxidation of Cu onto the surface of a copper electrode₂The O thin layer method has been widely reported for solar cell research. A thin 15nm layer (Phys. chem.103: 395(1999)) was obtained with appropriate control of the conditions, but the Cu formed₂Most of O is reduced into metallic copper under the action of photocathode, and nano Cu can not be prepared₂And (3) O powder. When using formonitrile and tetrahydrofuran as solvent,When the stabilizer is added, the metal copper is dissolved at the anode to obtain 2nm Cu₂O (J.Am.chem.Soc., 116: 7401 (1994)). However, this method requires slow electrolysis, resulting in a slow production rate. The process of anodic dissolution of copper in chloride salt medium to produce cuprous oxide is industrialized, the method is low in cost, mature and the product Cu₂O has stable quality and the process is easy to control (J.Appl.electrochen.20: 826(1990)), but the obtained Cu₂The diameter of O is several microns.

Disclosure of Invention

The invention aims to utilize the economical, mature and easily controlled anode dissolution process in chloride salt medium to produce Cu₂Preparation of nano Cu by virtue of O stability₂And (3) O material.

The principle of the invention is as follows: in the chloride salt (MeCl, Me ═ Na)⁺，K⁺，Li⁺，NH₄ ⁺R4N +, etc.), anodic dissolution of the copper anode during electrolysis can occur.

When the solution contains alkali, hydrolysis reaction occurs to generate Cu₂O；

Generally, newly formed Cu₂And the O continues to grow at the previously formed crystal center, so that the crystal grows up and finally micron-sized powder is formed. For the inventionThree methods for Cu suppression₂Particle size of O: (1) adding Cu to the electrolyte facing the copper anode₂A crystal growth inhibitor of O; the growth inhibitor can be polyvinyl alcohol, PVP and its derivatives, or copper surface adsorbent such as octyl ammonium bromide, benzotriazole, etc. (2) Adding a large amount of Cu into the electrolyte₂Nucleation centers of O or carriers containing nucleation centers. (3) Adding another nano material as Cu into the electrolyte₂A carrier of O. These three methods may be used alone or in combination. Cu thus obtained₂The amount of O particles is large and the granularity is small, and the nano Cu can be obtained by controlling the electrolytic current density and the electrolytic electric quantity and stopping electrolysis when the O particles grow to tens of nanometers₂And O. Then proper washing, stabilization and vacuum drying are carried out to finally obtain the stable nano Cu which can be stored for a long time₂O。

The scheme for realizing the purpose of the invention is as follows: preparation of nano cuprous oxide (Cu) by metal copper anodic oxidation method₂O) material, by anodic dissolution electrolysis of metallic copper anodes in chloride salt solutions, adding Cu to the electrolyte facing the copper anodes₂O crystal growth inhibitor, or/and crystal center, or carrier containing crystal center, or/and another nano material, and controlling chloride salt concentration in electrolyte, alkali concentration, electrolyte temperature, and electrolytic capacity to obtain Cu with particle size less than 100nm₂O powder or nano Cu containing carrier₂O, or a nanocomposite.

Cu as described above₂The crystal growth inhibitor of O is polyvinyl alcohol, polyvinylpyrrolidone and derivatives thereof,Octyl ammonium bromide, benzotriazole.

The concentration of the chloride salt MeCl solution in the electrolyte is 0.01-4.0M. Preferably 0.1 to 3.5M.

The concentration of the alkali contained in the electrolyte is generally 10-8 to 3.0M. Preferably 10-6-10-1M

The electrolysis is carried out at a temperature of generally 30 to 90 ℃. The preferred temperature range is 60-90 ℃.

The current density of the anode used in the above electrolysis is oneGenerally 0.005-5A/dm³. Preferably 0.1-2A/dm²。

The electrolytic capacity of the electrolysis per liter of the electrolyte is controlled to be below 20 ampere-hour. Preferably<5 A.h

Adding Cu into the electrolyte₂The carbon nano tube carrier of the O crystal center is used for obtaining the nano Cu₂An O-carbon nanotube composite.

Adding another nano material of titanium dioxide (TiO) into the electrolyte₂) Can produce Cu₂O-TiO₂A nanocomposite material.

Detailed Description

Example 1: using 1dm²The copper plate is used as an anode, titanium or nickel is used as a cathode, and a diaphragm is arranged between the cathode and the anode to prevent hydrogen bubbles generated by the cathode from contacting with generated Cu₂And O. 3.5MNaCl-0.01MNaOH is placed in the electrolytic bath as electrolyte. Suspending 1g of carbon nanotubes supported on monovalent copper crystal centers at 80 ℃ and 0.5A/dm²Electrolyzing for 60 minutes under the electrolysis condition of current density. After the electrolysis is finished, taking out the carbon-containing nano tube-Cu₂And removing the electrolyte by centrifugal separation or filtration, washing, stabilizing and vacuum-drying the precipitate.

Cu obtained by observation with a transmission electron microscope₂O-carbon nanotube composite, finding Cu₂O is in the form of dark granular particles grown on carbon nanotubes in light grey. Cu₂The particle size of O is between 20 and 80 nm. Cu₂The O particles are attached to the carbon nanotubes substantially in a monolayer and X-diffraction shows Cu₂The characteristic of O crystal. Cu₂The weight ratio of O to the carbon nano tube is as high as 1.5: 1.

Example 2: 0.001M benzotriazole was added to the chloride solution in the electrolytic cell described in example one, the amount of electrolytic electricity was controlled to 5 A.h/L, the electrolytic solution was vigorously stirred during the electrolysis, washed, dried, and observed with a microscope to give an octahedral Cu product₂O crystal with an average particle diameter of 60 to 80 nm.

Example 3: by vapour deposition on commercial graphite powderIntroducing trace copper element, suspending graphite powder containing copper crystal centers in the electrolyte shown in the first embodiment, electrolyzing, washing and drying under the conditions of the first embodiment to obtain Cu₂O-activated carbon composite, Cu shown by electron microscope observation₂O is attached to the active particles in the size of 10-80nmOn charcoal.

Example 4: in the chloride solution of the electrolytic cell described in example one, 1g of nano TiO was suspended₂(P25, Degussa, Germany), electrolyzed, washed and dried under the same conditions. Electron microscope observation and X-diffraction prove that the product is Cu₂O-TiO₂A composite nano photocatalyst.

Claims (4)

1. A process for preparing the nano cuprous oxide material by anodic oxidation of metallic copper features that the metallic copper anode is dissolved in the solution of chloride salt for electrolysis, and Cu is added to the electrolyte opposite to said metallic copper anode₂O crystal growth inhibitor, or/and crystal center, or carrier containing crystal center, or/and another nanometer material, and controlling the concentration of chloride salt in electrolyte to 0.01-4.0M and the concentration of alkali to 10^-8-3.0M, 30-90 deg.C, 20 A.h or less, and 0.005-5A/dm of anode current density³To obtain Cu with grain size less than 100nm₂O powder or nano Cu containing carrier₂O, or a nanocomposite.

2. The method of claim 1, wherein said Cu is₂The crystal growth inhibitor of O is polyvinyl alcohol, polyvinylpyrrolidone and derivatives thereof, octyl ammonium bromide and benzotriazole.

3. The method as set forth in claim 1, wherein Cu is added to the electrolyte₂The carbon nano tube carrier of the O crystal center is used for obtaining the nano Cu₂An O-carbon nanotube composite.

4. The method of claim 1The method is characterized in that another nano material titanium dioxide is added into the electrolyte to prepare Cu₂O-TiO₂A nanocomposite material.