Preparation method of a defect-free graphyne separation membrane

Abstract

The application relates to a preparation method of a defect-free graphdiyne separation membrane and belongs to the technical field of membrane separation. The preparation method of the defect-free graphdiyne separation membrane comprises the following steps: mechanically polishing a catalyst metal foil, then electrochemically polishing, cleaning, placing the obtained metal foil into etching solution to etch the metal foil into a metal foil with a plurality of grooves, then placing the metal foil into an activation solution to activate; subsequently, preparing a graphdiyne membrane on the metal foil, adding etching solution to the metal foil with the graphdiyne membrane to perform second etching, etching the original groove part into a through hole, and obtaining the defect-free graphdiyne separation membrane. The catalyst carrier active site of the graphdiyne separation membrane provided by the application is more and is more evenly distributed, the synthesis reaction of the graphdiyne is more easily promoted, and the growth process of the graphdiyne is more orderly.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing a defect-free graphdiyne separation membrane, belonging to the field of membrane separation technology. BACKGROUND

[0002] Graphdiyne (GDY) is a new type of carbon-based two-dimensional planar material after graphene and fullerene. It is a planar network structure material in which adjacent benzene rings are connected by 1,3-diethynyl bonds through conjugation. GDY has high π-π conjugation, wide interplanar spacing, average and dispersed pore structure, and controllable electronic structure, and has important application prospects in electronics, information, energy, catalysis, etc. At the same time, graphdiyne has a large triangular hole composed of C≡C bonds, with a pore size of about 0.4 nm, which can be used as a transmission channel for small molecule gases and prevent the passage of large molecules, playing a screening role. Therefore, graphdiyne is also an ideal separation membrane material for realizing the separation of various gases, and has very high application prospects.

[0003] At present, there is still a big gap between the separation performance of the graphdiyne separation membrane prepared by the in-situ synthesis method (application patent number: CN114917773A) and the theoretical calculation. The reasons for this gap are mainly as follows: first, the internal factors: the catalytic sites of the metal foil are too few and unevenly distributed during the synthesis process, which leads to insufficient synthesis of graphdiyne and causes the generation of defects in the graphdiyne separation membrane; second, external factors: the metal foil substrate for growing graphdiyne has a texture, and the graphdiyne grown according to the texture of the metal foil will have cracks, causing performance loss. Third, synthesis factors: the existing patent graphdiyne synthesis method is one-pot liquid phase synthesis method (application patent number: CN114917773A). Due to the simultaneous addition of reactants in one-pot synthesis, the reaction is violent and the reaction process is not easy to control, and the metal foil catalytic reaction is not uniform, which ultimately leads to uneven growth of the graphdiyne separation membrane and causes the generation of defects.

[0004] If the synthesis route of the graphdiyne separation membrane can be optimized from these aspects, a defect-free graphdiyne separation membrane can be obtained, which can improve its separation performance and promote the application of the graphdiyne separation membrane in the field of gas separation. SUMMARY

[0005] The main purpose of the present application is to overcome the shortcomings of the prior art, and to provide a method for preparing a defect-free graphdiyne separation membrane, which can significantly improve the gas separation performance of the graphdiyne separation membrane. The specific technical scheme of the present application is as follows:

[0006] A method for preparing a defect-free graphdiyne separation membrane, comprising the following steps:

[0007] ​The catalyst metal foil is mechanically polished, then electrochemically polished, and after cleaning, the obtained metal foil is placed in an etching solution to etch into a metal foil with a plurality of grooves, and then placed in an activation solution for activation; subsequently, a graphdiyne film is prepared on the metal foil, the metal foil with the graphdiyne film is added dropwise with an etching solution for a second etching, the original groove part is etched into a through hole, and a defect-free graphdiyne separation film is obtained.

[0008] In the technical scheme, the etching step is: coating photosensitive ink on one side of the metal foil, printing black light shielding points on the film paper, exposing the light shielding points and the metal foil coated with the ink under the ultraviolet lamp; and washing the remaining ink with a developing solution, so as to obtain a template layer with uniform holes on the metal foil; and then placing the metal foil in an etching solution to etch, so as to obtain a metal foil with grooves of fixed positions and etching depths.

[0009] In the technical scheme, the arrangement position of the grooves can be controlled by the black light shielding points printed on the film paper; and the etching depth can be controlled by controlling the concentration of the etching solution and the etching time.

[0010] In the technical scheme, the metal foil is one of a copper foil, a nickel foil, a platinum foil, a palladium foil, an aluminum foil and a silver foil.

[0011] In the technical scheme, the mechanical polishing mode is to polish the metal foil through sandpaper, and the sandpaper has a mesh size of 5000-20000; and the polishing mode is to polish and grind the metal foil through sandpaper with increasing mesh size, and the polishing and grinding time is 10-20 min.

[0012] In the technical scheme, the electrochemical polishing is to use the metal foil obtained through mechanical polishing as an anode, use a stainless steel plate as a cathode, and perform electrochemical polishing in an electrolyte,

[0013] In the technical scheme, the electrolyte is hydrochloric acid, sulfuric acid or phosphoric acid aqueous solution; the mass fraction of the electrolyte used in the electrochemical polishing is 10-15 wt.%, the ratio of direct current to the area of the anode metal foil is 2-10 A / dm 2 , and the electrolysis time is 10-40 min.

[0014] In the technical scheme, the metal foil obtained through electrochemical polishing is cleaned and dried, and the cleaning liquid for the electrochemical polishing is one of deionized water, anhydrous ethanol, 10 wt.% hydrochloric acid and acetone.

[0015] In the technical scheme, the obtained metal foil is placed in an etching solution to etch into a metal foil with grooves, and the etching solution is an aqueous solution of ammonium persulfate, sodium persulfate, ferric chloride or nitric acid, the concentration of the etching solution is 0.5-5 mol / L, the etching temperature is 25-30℃, and the etching time is 0.5-24 h.

[0016] In the technical scheme, the polished metal foil is placed in an activation solution for activation, wherein the activation solution is one of a palladium chloride solution, a palladium nitrate solution, a palladium acetate solution, chloroplatinic acid, platinum nitrate, platinum sulfate, citric acid, acetic acid, and an oxalic acid aqueous solution; the concentration of the activation solution is 0.1-1.0 mol / L, the activation temperature is 20-70℃, and the activation time is 1-5 h.

[0017] In the technical scheme, the graphdiyne film is prepared by the following method: a metal foil with a plurality of grooves, hexakis (trimethylsilyl) -ethynyl benzene, tetra-n-butylammonium fluoride, and acetone are placed in a reaction container, and N.N.N`N`-tetramethylethylenediamine (TMEDA) and pyridine are slowly added to the reaction container under an argon or nitrogen atmosphere for reaction.

[0018] Further, the mass ratio of hexakis (trimethylsilyl) -ethynyl benzene: tetra-n-butylammonium fluoride: acetone: N.N.N`N`-tetramethylethylenediamine (TMEDA): pyridine is (30-50):(1-5):(200-300):(8-15):(80-120); the reaction temperature is 50-80℃, and the reaction time is 8-10 h.

[0019] In the technical scheme, the second etching step is as follows: the edge of the metal foil with the graphdiyne film is wrapped with waterproof tape, and an etching solution is added to the groove side of the metal foil for secondary etching, so that the etching solution penetrates the groove to form a through hole; the waterproof tape is removed, and the graphdiyne separation film without defects is obtained after cleaning and drying,

[0020] In the technical scheme, the etching solution is an aqueous solution of ammonium persulfate, sodium persulfate, ferric chloride, or nitric acid, the etching solution concentration is 0.5-5 mol / L, the etching temperature is 25-30℃, and the etching time is 0.5-8 h.

[0021] The application has the beneficial effects that: the catalyst carrier metal foil for synthesizing graphdiyne is physically and mechanically polished, and then electrochemically polished, so that the metal foil with a smooth surface without traces is obtained, after the metal foil is etched and activated, the preparation of graphdiyne is carried out, then the metal foil is etched into a through hole, and a defect-free graphdiyne separation membrane is obtained. The catalyst carrier obtained by the method has more active sites and more evenly distributed active sites, which is more conducive to promoting the synthesis reaction of graphdiyne, and the growth process of graphdiyne is more orderly. At the same time, the synthesis method of graphdiyne is improved from one-pot method to two-step synthesis method. N.N.N`N`-tetramethylethylenediamine (TMEDA) nitrogen ligand is introduced, and is added to the reaction system in a slow dropwise manner. This method can better control the catalytic degree of metal ions and the reaction rate. Thus, the prepared graphdiyne membrane has a complete structure, no defects, and the separation performance is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a metallographic microscope magnified picture of the copper foil of Example 1, (a) untreated metal foil; (b) metal foil after activation.

[0023] Figure 2 It is a surface SEM picture of the graphdiyne separation membrane prepared from the copper foil in Example 1, (a) untreated copper foil; (b) copper foil after activation. DETAILED DESCRIPTION

[0024] The following non-limiting examples can make those skilled in the art more fully understand the present application, but do not limit the present application in any way.

[0025] In the following examples, the test methods described are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0026] A preparation method of a defect-free graphdiyne separation membrane, comprising the following steps:

[0027] 1) Surface treatment: polish the metal foil required for synthesizing graphdiyne separation membrane. Then, the metal foil is used as an anode, and a stainless steel plate is used as a cathode to perform electrochemical polishing treatment. After cleaning, the metal foil with a smooth surface without traces is obtained.

[0028] 2) Surface activation: after the metal foil obtained in step 1) is etched, a metal foil with several grooves is obtained, and then is placed in a solution of palladium salt, platinum salt or organic acid for activation treatment to obtain an activated metal foil.

[0029] 3) Synthesis of graphdiyne film: the metal foil obtained in step 2) is placed in a flask, and hexa-silane-based acetylene phenyl, tetra-n-butyl ammonium fluoride, and acetone are added; N.N.N`N`-tetramethylene ethylenediamine (TMEDA), pyridine are slowly dropped into the flask under argon or nitrogen atmosphere to carry out polymerization reaction, thereby forming a graphdiyne film on the metal foil.

[0030] 4) Preparation of graphdiyne separation film: after the reaction, the metal foil with the graphdiyne film is dropped into an etching solution for a second etching, and after the etching into a through hole, the metal foil is cleaned and dried, thereby obtaining a defect-free graphdiyne separation film.

[0031] In the above technical solution, in step 1), the metal foil is one of copper foil, nickel foil, platinum foil, palladium foil, aluminum foil, and silver foil.

[0032] In the above technical solution, in step 1), the polishing method is polishing and grinding by increasing the mesh number of sandpaper; the sandpaper type is 5000, 10000, and 20000 mesh; and the polishing time is 10-20 min.

[0033] In the above technical solution, in step 1), the electrolyte used in the electrochemical polishing is hydrochloric acid, sulfuric acid, or phosphoric acid aqueous solution.

[0034] In the above technical solution, in step 1), the mass fraction of the electrolyte used in the electrochemical polishing is 10-15 wt.%, the ratio of direct current to the area of the anode metal foil is 2-10 A / dm 2 , and the electrolysis time is 10-40 min.

[0035] In the above technical solution, in step 1), the cleaning solution is one of deionized water, ethanol, 10 wt.% hydrochloric acid, and acetone.

[0036] In the above technical solution, in step 2), the etching solution is an aqueous solution of ammonium persulfate, sodium persulfate, ferric chloride, or nitric acid; the etching solution concentration is 0.5-5 mol / L, the etching temperature is 25-30℃, and the etching time is 0.5-24 h.

[0037] In the above technical solution, in step 2), the palladium salt solution is one of palladium chloride, palladium nitrate, and palladium acetate aqueous solution; the platinum salt solution is one of chloroplatinic acid, platinum nitrate, and platinum sulfate aqueous solution; and the organic acid solution is one of citric acid, acetic acid, and oxalic acid aqueous solution.

[0038] In the above technical solution, in step 2), the concentration of the activation solution is 0.1-1.0 mol / L, the activation temperature is 20-70℃, and the activation time is 1-5 h.

[0039] In the above technical solution, in the step 3), the reaction amount is: according to the mass fraction ratio, hexamethylsilane ethynyl benzene: tetra-n-butyl ammonium fluoride: acetone: N.N.N`N`-tetramethylene ethylenediamine (TMEDA): pyridine is (30-50):(1-5):(200-300):(8-15):(80-120);

[0040] In the above technical solution, in the step 3), the reaction temperature is 50-80℃; the reaction time is 8-10h;

[0041] In the above technical solution, in the step 4), the second etching step is: the edge of the metal foil with the graphdiyne film is wrapped with waterproof tape, and the etching solution is added to the groove side of the metal foil again for secondary etching, and the etching solution will penetrate the groove to form a through hole; the waterproof tape is removed, and after cleaning and drying, a defect-free graphdiyne separation film is obtained.

[0042] In the above technical solution, in the step 4), the etching solution is an aqueous solution of ammonium persulfate, sodium persulfate, ferric chloride or nitric acid; the etching solution concentration is 0.5-5mol / L, the etching temperature is 25-30℃, and the etching time is 0.5-8h.

[0043] Example 1:

[0044] Cut a certain area of copper foil, and polish it for 10min in order of increasing mesh according to 5000, 10000 and 20000 mesh sandpaper. Prepare 10wt.% H3PO4 electrolyte, use the polished copper foil as anode and stainless steel plate as cathode, and the direct current / copper foil area is 2A / dm 2The copper foil is electrochemically polished in 10 wt. % H3PO4 electrolyte for 10 min. The electrochemically polished copper foil is washed with deionized water for three times and dried. The photosensitive ink is coated on the copper foil, and black shading points are printed on the photosensitive ink using film paper. The shading points and the copper foil coated with the photosensitive ink are exposed to ultraviolet light. The remaining photosensitive ink is washed away using a developing solution, so that a template layer with uniform holes is obtained on the copper foil. Then, the copper foil is placed in an etching solution to etch the copper foil, so that a metal foil with grooves of fixed positions and etching depths is obtained, wherein the etching solution is a 0.5 mol / L sodium persulfate aqueous solution, and the etching is performed at 25 °C for 0.5 h. A 0.1 mol / L palladium chloride aqueous solution is prepared as an activation solution, and then the copper foil is placed in the activation solution and activated at 20 °C for 1 h. The activated copper foil is added into a flask, and 30 mg of hexakis (trimethylsilyl) ethynylbenzene, 1 mL of tetra-n-butylammonium fluoride, and 300 mL of acetone are added. Then, 10 mL of N.N.N`N`-tetramethylethylenediamine (TMEDA) is slowly added dropwise under an argon atmosphere, and 50 mL of pyridine is added dropwise under an argon atmosphere. The reaction is performed at 50 °C for 8 h. Then, the copper foil with the graphdiyne film is wrapped with waterproof tape at the edges, and the etching solution is added dropwise to the side of the groove of the copper foil again for secondary etching. The etching solution can penetrate the groove to form a through hole. After the waterproof tape is removed and the copper foil is cleaned and dried, a graphdiyne separation film with a smooth surface and no defects is obtained, wherein the etching solution is a 0.5 mol / L sodium persulfate aqueous solution, and the etching is performed at 25 °C for 8 h. The gas separation performance of the obtained separation film is shown in Table 1.

[0045] Example 2

[0046] According to the experimental method of Example 1, the difference between Example 1 and Example 2 is that the metal foils used are aluminum foils and nickel foils, respectively. The gas separation performance of the obtained separation films is shown in Table 1.

[0047] Table 1. Gas separation performance of graphdiyne separation films prepared using different metal foils

[0048]

[0049] Example 3

[0050] According to the experimental method of Example 1, the difference between Example 1 and Example 3 is that after the copper foil is mechanically polished, it is transferred to 10 wt. % H3PO4, 15 wt. % H3PO4, 10 wt. % H2SO4, 15 wt. % H2SO4, 10 wt. % HCl, and 15 wt. % HCl electrolyte for electrochemical polishing, respectively. The gas separation performance of the obtained separation films is shown in Table 2.

[0051] Table 2. Gas separation performance of graphdiyne separation films prepared by polishing copper foils in different electrolytes

[0052]

[0053] Example 4:

[0054] According to the experimental method of Example 1, except that the copper foil was placed in the electrolyte for electrochemical polishing for 25 and 40 minutes, respectively. The gas separation performance of the obtained graphene-based separation membrane is shown in Table 3.

[0055] Table 3. Gas separation performance of graphene-based separation membranes prepared from copper foils with different electrolysis times

[0056]

[0057] Example 5:

[0058] According to the experimental method of Example 1, except that the ratio of direct current to metal foil area was 5 and 10 A / dm2 when the copper foil was placed in the electrolyte for electrochemical polishing. The gas separation performance of the obtained graphene-based separation membrane is shown in Table 4. 2

[0059] Table 4. Gas separation performance of graphene-based separation membranes prepared from copper foils polished with different current densities

[0060]

[0061]

[0062] Example 6:

[0063] According to the experimental method of Example 1, except that after electrochemical polishing of the copper foil, it was cleaned with 10 wt.% HC1, anhydrous ethanol, and acetone three times, respectively, and then dried. The gas separation performance of the obtained graphene-based separation membrane is shown in Table 5.

[0064] Table 5. Gas separation performance of graphene-based separation membranes prepared from copper foils cleaned with different cleaning solutions

[0065]

[0066] Example 7:

[0067] According to the experimental method of Example 1, except that after etching treatment of the copper foil, it was transferred to palladium nitrate, chloroplatinic acid, and oxalic acid activation solutions, respectively, for activation. The gas separation performance of the obtained graphene-based separation membrane is shown in Table 6.

[0068] Table 6. Gas separation performance of graphene-based separation membranes prepared from copper foils activated with different activation solutions

[0069]

[0070] Example 8:

[0071] ​The experimental method is according to Example 1, except that the concentration of the activation solution is 0.7, 1.0 mol / L respectively when the copper foil is put into the activation solution for activation. The gas separation performance of the obtained graphdiyne separation membrane is shown in Table 7.

[0072] Table 7 Separation performance of graphdiyne separation membrane prepared by copper foil activated by different concentrations of activation solution

[0073]

[0074] Example 9:

[0075] The experimental method is according to Example 1, except that the activation reaction temperature is 40, 70 ℃ respectively when the copper foil is put into the activation solution for activation. The gas separation performance of the obtained separation membrane is shown in Table 8.

[0076] Table 8 Separation performance of graphdiyne separation membrane prepared by copper foil activated by different activation temperatures

[0077]

[0078] Example 10:

[0079] The experimental method is according to Example 1, except that the activation time is 3, 5 h respectively when the copper foil is put into the activation solution for activation. The gas separation performance of the obtained separation membrane is shown in Table 9.

[0080] Table 9 Separation performance of graphdiyne separation membrane prepared by copper foil activated by different activation times

[0081]

[0082] Example 11:

[0083] The experimental method is according to Example 1, except that the amount of hexakis (trimethylsilyl) ethynylbenzene added is 50 mg. The gas separation performance of the obtained separation membrane is shown in Table 10.

[0084] Example 12:

[0085] The experimental method is according to Example 1, except that the amount of tetra-n-butylammonium fluoride added is 5 mL. The gas separation performance of the obtained separation membrane is shown in Table 10.

[0086] Example 13:

[0087] The experimental method is according to Example 1, except that the amount of N.N.N`N`-tetramethylethylenediamine (TMEDA) is 15 mL. The gas separation performance of the obtained separation membrane is shown in Table 10.

[0088] Example 14:

[0089] The experimental method was the same as that of Example 1, except that the amount of pyridine used was 100 mL. The gas separation performance of the obtained separation membrane is shown in Table 10.

[0090] Example 15:

[0091] The experimental method was the same as that of Example 1, except that the amount of acetone added was 400 mL. The gas separation performance of the obtained separation membrane is shown in Table 10.

[0092] Example 16:

[0093] The experimental method was the same as that of Example 1, except that the reaction temperature was 80°C. The gas separation performance of the obtained separation membrane is shown in Table 10.

[0094] Example 17:

[0095] The experimental method was the same as that of Example 1, except that the reaction time was 10 h. The gas separation performance of the obtained separation membrane is shown in Table 10.

[0096] Table 10. Gas separation performance of the graphdiyne separation membranes prepared under different reaction conditions

[0097]

[0098] Example 18:

[0099] The experimental method was the same as that of Example 1, except that the etching solution used was an aqueous solution of ammonium persulfate. The gas separation performance of the obtained separation membrane is shown in Table 11.

[0100] Example 19:

[0101] The experimental method was the same as that of Example 1, except that the concentration of the etching solution used was 5 mol / L. The gas separation performance of the obtained separation membrane is shown in Table 11.

[0102] Example 20:

[0103] The experimental method was the same as that of Example 1, except that the etching temperature was 30°C. The gas separation performance of the obtained separation membrane is shown in Table 11.

[0104] Example 21:

[0105] The experimental method was the same as that of Example 1, except that the first etching time was 24 h. The gas separation performance of the obtained separation membrane is shown in Table 11.

[0106] Example 22:

[0107] According to the experimental method of Example 1, except that the second etching time was 2 h. The gas separation performance of the obtained separation membrane is shown in Table 11.

[0108] Table 11 Separation performance of graphdiyne separation membranes prepared by etching copper foil under different etching conditions

[0109]

[0110]

Claims

1. A method for preparing a defect-free graphdiyne separation membrane, characterized in that: Includes the following steps: The catalyst metal foil was mechanically polished, then electrochemically polished, and cleaned. The resulting metal foil was then etched in an etching solution to create a foil with several grooves, followed by activation in an activation solution. Subsequently, a graphdiyne film was prepared on the metal foil. The metal foil with the graphdiyne film was then subjected to a second etching process by adding etching solution, which etched the original grooves into through-holes, resulting in a defect-free graphdiyne separation membrane. Mechanical polishing involves polishing the metal foil with sandpaper of 5000-20000 grit; grinding involves polishing with sandpaper of progressively increasing grit, with a grinding time of 10-20 minutes. Electrochemical polishing involves using a mechanically polished metal foil as the anode and a stainless steel plate as the cathode, performing electrochemical polishing in an electrolyte solution. The electrolyte solution is an aqueous solution of hydrochloric acid, sulfuric acid, or phosphoric acid. The mass fraction of the electrolyte used in the electrochemical polishing is 10-15 wt.%, and the ratio of direct current to the area of ​​the anode metal foil is 2-10 A / dm². 2 The electrolysis time is 10-40 min; The graphdiyne separation membrane is prepared as follows: a metal foil with several grooves, hexasilyl ethynylbenzene, tetra-n-butylammonium fluoride, and acetone are placed in a reaction vessel. Under an argon or nitrogen atmosphere, N,N,N',N'-tetramethylenediamine (TMEDA) and pyridine are slowly added dropwise to the reaction vessel for reaction. The mass ratio of hexasilyl ethynylbenzene: tetra-n-butylammonium fluoride: acetone: N,N,N',N'-tetramethylenediamine (TMEDA): pyridine is (30~50): (1~5): (200~300): (8~15): (80~120). The reaction temperature is 50-80 °C, and the reaction time is 8-10 h.

2. The method according to claim 1, characterized in that: The metal foil is one of copper foil, nickel foil, platinum foil, palladium foil, aluminum foil, and silver foil.

3. The method according to claim 1, characterized in that: The metal foil obtained by electrochemical polishing is cleaned and dried, wherein the electrochemical polishing cleaning solution is one of deionized water, anhydrous ethanol, 10wt.% hydrochloric acid, and acetone.

4. The method according to claim 1, characterized in that: Photosensitive ink is coated onto one side of a metal foil. Black light-blocking dots are printed on film. The light-blocking dots and the ink-coated metal foil are exposed to ultraviolet light. The remaining ink is washed away with a developer, resulting in a template layer with uniform holes on the metal foil. The metal foil is then immersed in an etching solution for etching, resulting in a metal foil with grooves of fixed positions and etching depths. The etching solution is an aqueous solution of ammonium persulfate, sodium persulfate, ferric chloride, or nitric acid, with a concentration of 0.5-5 mol / L, an etching temperature of 25-30 ℃, and an etching time of 0.5-24 h.

5. The method according to claim 1, characterized in that: The polished metal foil is placed in an activation solution for activation. The activation solution is one of the following: palladium chloride, palladium nitrate, palladium acetate, chloroplatinic acid, platinum nitrate, platinum sulfate, citric acid, acetic acid, or oxalic acid aqueous solution. The concentration of the activation solution is 0.1-1.0 mol / L, the activation temperature is 20-70 ℃, and the activation time is 1-5 h.

6. The method according to claim 1, characterized in that: The second etching step is as follows: The edges of the metal foil with the graphdiyne film are wrapped with waterproof tape. Etching solution is then dripped onto one side of the groove on the metal foil for secondary etching. The etching solution penetrates the groove, forming a through-hole. After removing the waterproof tape, cleaning, and drying, a defect-free graphdiyne separation membrane is obtained. The etching solution is an aqueous solution of ammonium persulfate, sodium persulfate, ferric chloride, or nitric acid, with a concentration of 0.5-5 mol / L, an etching temperature of 25-30 ℃, and an etching time of 0.5-8 h.

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