A method for preparing graphene composite porous copper foam

Abstract

The invention discloses a method for preparing a graphene composite porous copper foam. The foam material has an interpenetrating network structure of graphene foam and a porous copper foam skeleton. The copper foam skeleton provides strength support for the overall structure, and the three-dimensional graphene network plays a role in powder forming. At the same time, the porosity of the composite copper foam material is increased, excessive sintering is prevented, and the corrosion resistance of the copper foam material is greatly improved.

Description

Technical field:

[0001] The invention relates to the technical field of preparation of foam copper materials, and in particular to a method for preparing graphene composite porous copper foam. Background technology:

[0002] Copper foam is a new type of multifunctional material that not only retains the good electrical conductivity and ductility of metallic copper, but also has the characteristics of foam materials, low density and a large number of open or closed pore structures. Copper foam has low preparation cost and good electrical conductivity. It is widely used in catalyst carriers, electrode materials, silencers and shielding devices, heat conduction materials and other fields. However, due to the poor corrosion resistance of copper itself, its service life and application areas are also limited.

[0003] There are currently three main methods for preparing foam copper materials. The first is powder metallurgy, in which copper powder and a foaming agent are fully mixed and sintered, and pores are formed using the foaming agent. The foam copper produced by this method has an irregular pore structure and a large number of closed-cell structures. The second is electrochemical deposition, which produces foam copper with high porosity, but the method is complicated to operate and causes greater pollution. The third is a sintering-demolding process, in which copper powder, sodium chloride and additives are mixed and pressed into a green body. After sintering, impurities are dissolved with water, and the foam copper is obtained by washing and drying. This method has a complex process and a low open porosity. Summary of the invention:

[0004] The present invention provides a method for preparing a graphene composite porous copper foam, and the specific steps are as follows:

[0005] (1) adding graphene oxide to an aprotic organic solvent and stirring to obtain a graphene oxide dispersion, wherein the aprotic solvent is selected to avoid the reaction between the solvent and copper during a high-temperature solvent thermal process, thereby preventing oxidation or corrosion of the copper;

[0006] (2) adding copper powder or copper fiber to the graphene oxide dispersion and stirring to obtain a uniform dispersion;

[0007] (3) adding the dispersion formed by the graphene oxide and copper powder or copper fiber into a high-temperature reaction kettle to perform a solvent thermal reaction to obtain a graphene composite porous copper foam material with a solvent, wherein the graphene oxide will produce chemical crosslinks during the solvent thermal process to form a network structure, and the copper powder or copper fiber will be wrapped in the network;

[0008] (4) removing the organic solvent from the composite material and performing a sintering treatment under an inert atmosphere to obtain a graphene composite porous copper foam. The sintering treatment not only forms a foam copper structure from copper powder or copper fiber, but also reduces graphene oxide to obtain a highly conductive graphene network structure.

[0009] Preferably, the aprotic organic solvent is selected from one or a mixture of any proportion of two or more of acetonitrile, N-methylpyrrolidone, dimethyl sulfoxide, benzene, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran and acetone.

[0010] Preferably, the graphene oxide used to prepare the graphene oxide dispersion is a single-layer graphene oxide or a few-layer (2-10 layers) graphene oxide, preferably a single-layer graphene oxide; the concentration of graphene oxide in the graphene oxide dispersion is 0.2 mg / mL-20 mg / mL, preferably 0.5-2 mg / mL.

[0011] Preferably, the particle size of the copper powder is 1 nm-40 μm, the length of the copper fiber is 5 nm-100 μm, and the diameter of the copper fiber is 1 nm-10 μm.

[0012] Preferably, in the dispersion formed by the graphene oxide and copper powder or copper fiber, the copper powder or copper fiber accounts for 80%-99.9% of the total solid mass content, and the graphene oxide accounts for 0.1%-20% of the total solid mass content.

[0013] Preferably, the reaction temperature of the solvent thermal reaction is 100° C.-250° C., and the reaction time is 6 h-48 h.

[0014] Preferably, the method for removing the aprotic organic solvent may be atmospheric pressure drying or vacuum drying, preferably vacuum drying, with a drying temperature of 80-250° C. and a drying time of 6-48 h.

[0015] Preferably, the sintering process is carried out in an inert atmosphere, which refers to nitrogen or argon or a mixed atmosphere of the two.

[0016] Preferably, the sintering temperature is 700-1100° C., preferably 900-1000° C., and the sintering time is 0.2-12 h.

[0017] Preferably, the prepared graphene composite porous copper foam material consists of a porous foam copper skeleton and a graphene network, and has a porosity of 20%-95%.

[0018] The beneficial effects of the present invention are:

[0019] Graphene has the characteristics of high electrical conductivity, high flexibility, and stable physical and chemical properties. It has broad application prospects in the fields of electrode materials, catalytic conversion, wave absorption and shielding. The present invention utilizes a solvent thermal self-assembly method, based on graphene sheets as building units, and connects the graphene sheets to each other through chemical bonds to form a three-dimensional graphene conductive network. At the same time, copper powder or copper fiber is wrapped in the graphene network, and then sintered to obtain a graphene composite foam copper material.

[0020] The present invention combines the powder forming method and the solvent thermal self-assembly method, has a simple preparation process, low equipment requirements, and does not require the use of sacrificial agents, foaming agents, etc.

[0021] The present invention utilizes graphene to partially wrap copper powder or copper fiber to avoid over-sintering during the sintering process, thereby ensuring that the composite porous copper foam has a high porosity, and by changing parameters such as graphene content and sintering temperature, the porosity and density of the composite material can be effectively regulated;

[0022] Graphene has excellent stability and corrosion resistance. The composite of graphene network can greatly improve the corrosion resistance of copper foam itself and increase the service life of composite materials.

[0023] The copper foam material prepared by the present invention has an interpenetrating network structure of graphene foam and a porous copper foam skeleton. The copper foam skeleton provides strength support for the overall structure, and the three-dimensional graphene network plays a role in powder forming, while increasing the porosity of the composite copper foam material, preventing excessive sintering, and greatly improving the corrosion resistance of the copper foam material. Description of the drawings:

[0024] Figure 1 This is an optical photograph of the graphene composite porous copper foam of the present invention;

[0025] Figure 2 This is a scanning electron microscope image of the graphene composite porous copper foam in the present invention. Specific implementation method:

[0026] The present invention is further described with reference to the embodiments.

[0027] Embodiment 1:

[0028] Take 30 mg of graphene oxide powder and add it to 30 mL of N,N-dimethylformamide, stir until evenly dispersed, prepare a 1 mg / mL dispersion, then add 0.6 g of copper powder with an average particle size of 500 nm, and stir mechanically for 2 hours to mix evenly. After that, pour the slurry into a 50 mL stainless steel reactor with a polytetrafluoroethylene liner, and the reaction temperature is 200 ° C and the reaction time is 12 hours. The graphene composite copper foam material formed after the solvent thermal reaction is vacuum dried at 150 ° C for 24 hours to remove the solvent. Finally, sinter at 1000 ° C for 2 hours under argon atmosphere to obtain a graphene composite copper foam material, such as Figure 1 , as shown in 2.

[0029] Embodiment 2:

[0030] Take 60mg of graphene oxide powder and add it to 30mL of N-methylpyrrolidone, stir until evenly dispersed, prepare a 2mg / mL dispersion, then add 1.5g of copper powder with an average particle size of 2μm, and mechanically stir for 5h to mix evenly. After that, pour the slurry into a 50mL stainless steel reactor with a polytetrafluoroethylene liner, the reaction temperature is 220°, and the reaction time is 12h. The graphene composite copper foam material formed after the solvent thermal reaction is vacuum dried at 200℃ for 24h to remove the solvent. Finally, sinter at 950℃ for 3h in an argon atmosphere to obtain a graphene composite copper foam material.

[0031] Embodiment 3:

[0032] Take 30mg of graphene oxide powder and add it to 30mL of N,N-dimethylformamide, stir until evenly dispersed, prepare a 1mg / mL dispersion, then add 1g of copper fiber, the average length of the copper fiber is 10μm, the length-to-diameter ratio is 200, and mechanically stir for 2h to mix evenly. After that, pour the slurry into a 50mL stainless steel reactor with a polytetrafluoroethylene liner, the reaction temperature is 200℃ and the reaction time is 6h. The graphene composite copper foam material formed after the solvent thermal reaction is vacuum dried at 150℃ for 24h to remove the solvent. Finally, sinter at 1000℃ for 0.5h in an argon atmosphere to obtain a graphene composite copper foam material.

[0033] The above descriptions are only preferred embodiments of the present invention, and all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a graphene composite porous copper foam, characterized in that: The specific steps are as follows: S1. Adding graphene oxide to an aprotic organic solvent and stirring to obtain a graphene oxide dispersion, wherein the graphene oxide is a single-layer graphene oxide or 2-10 layers of graphene oxide, and the concentration of graphene oxide in the graphene oxide dispersion is 0.2 mg / mL-20 mg / mL; S2. Add copper powder or copper fiber to the graphene oxide dispersion and stir to obtain a uniform dispersion, wherein the particle size of the copper powder is 1 nm-40 μm, the length of the copper fiber is 5 nm-100 μm, and the diameter of the copper fiber is 1 nm-10 μm. In the dispersion formed by graphene oxide and copper powder or copper fiber, the copper powder or copper fiber accounts for 80%-99.9% of the total solid mass content, and the graphene oxide accounts for 0.1%-20% of the total solid mass content; S3, adding the dispersion formed by the graphene oxide and copper powder or copper fiber into a high-temperature reaction kettle, performing a solvent thermal reaction, and obtaining a graphene composite porous copper foam material with a solvent, wherein the graphene oxide will produce chemical crosslinking during the solvent thermal process to form a network structure, and the copper powder or copper fiber will be wrapped in the network; S4. Remove the organic solvent from the composite material and perform sintering treatment under an inert atmosphere at a sintering temperature of 700-1100ºC for a sintering time of 0.2-12 h to obtain a graphene composite porous copper foam. The sintering treatment forms a foam copper structure from copper powder or copper fiber on the one hand, and reduces graphene oxide on the other hand to obtain a highly conductive graphene network structure. The obtained graphene composite porous copper foam material consists of a porous foam copper skeleton and a graphene network with a porosity of 20%-95%.

2. The method for preparing a graphene composite porous copper foam according to claim 1, characterized in that: The aprotic organic solvent in step S1 is selected from one or a mixture of any proportion of two or more of acetonitrile, N-methylpyrrolidone, dimethyl sulfoxide, benzene, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran and acetone.

3. The method for preparing a graphene composite porous copper foam according to claim 1, characterized in that: The reaction temperature of the solvent thermal reaction in step S3 is 100°C-250°C, and the reaction time is 6 h-48 h.

4. The method for preparing a graphene composite porous copper foam according to claim 1, characterized in that: The method for removing the aprotic organic solvent in step S4 uses normal pressure drying or vacuum drying, the drying temperature is 80-250 ºC, and the drying time is 6-48 h.

5. The method for preparing a graphene composite porous copper foam according to claim 1, characterized in that: The inert atmosphere in step S4 refers to nitrogen or argon or a mixed atmosphere of the two.

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