CN114351234B - Method for preparing two-dimensional material by electrochemical etching based on coordination chemistry and detection method thereof - Google Patents

Abstract

The invention discloses a method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry and a detection method thereof. 1. The method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry provided by the invention has green, Safe and efficient, the reagents used are harmless to the human body and the environment, and have obvious etching effects on the target material. 2. The method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry provided by the present invention is universal in theory. Under the premise of conforming to objective laws, select a suitable complex as the active substance of the electrolyte, and then Complete etching of most materials. 3. The method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry provided by the present invention, compared with the existing electrochemical etching system, has a clearer explanation of the mechanism, and has great guiding significance for the selection of electrolytes, and the operation It is simple, easy to implement, high in efficiency, and suitable for large-scale industrial production and application.

Description

A method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry and its detection test method

Technical field:

The invention relates to the technical field of chemical engineering, in particular to a method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry and a detection method thereof.

Background technique:

Two-dimensional materials have a very high specific surface area and can provide many surface active sites, so they have extremely broad application prospects in the fields of energy storage, catalysis, and photoelectric conversion. At present, effective methods for obtaining 2D materials are mainly divided into bottom-up and top-down methods. The typical method of the former is vapor deposition, but the yield is very low; the typical method of the latter is chemical stripping, although the yield is high, but the reagents usually used have higher risk, such as the Hummer's method used in exfoliating graphene with strong Corrosive concentrated sulfuric acid has major safety hazards in experimental operations.

MXene materials are widely used due to their ultra-high electrical conductivity, abundant and tunable surface functional groups, and strong processability. However, at present, the entire MXene family is mainly obtained by chemically etching the A element in its precursor MAX by using hydrofluoric acid. As we all know, hydrofluoric acid is a very dangerous chemical substance, and long-term use is harmful to the human body. The MBene family also faces the same problem, so there is an urgent need for a green, safe and efficient method to obtain this type of two-dimensional materials.

The electrochemical etching method is a method for obtaining two-dimensional materials from top to bottom. It mainly uses electrochemical reactions to extract some elements in the three-dimensional bulk phase formed by chemical bonding of two-dimensional forms, so as to obtain the target two-dimensional materials. . The core of implementing an electrochemical reaction lies in the design of the electrolytic cell, and the key of the electrolytic cell lies in the selection of the electrolyte. At present, the commonly used effective electrolytes are aqueous acidic or alkaline, which have achieved considerable results, but these electrolytes have certain risks and are not clearly targeted, resulting in a lack of accurate purpose in the reaction and driving The potential of the electrochemical reaction is high, that is, it has a high energy barrier.

Invention content:

The purpose of the present invention is to solve the existing problems, and to provide a three-dimensional bulk phase formed by chemically bonding two-dimensional forms by electrochemical etching based on the idea of coordination chemistry to select suitable ligands as active substances in the electrolyte. Precursors, a method for obtaining high-quality two-dimensional materials, a method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry, and its detection method.

Technical solutions of the present invention are as follows:

A method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry, comprising the steps of:

Step 1: First add the active substance to a certain volume of deionized water, and ultrasonically stir it under 100W power to fully dissolve it, then add a certain amount of strong electrolyte to the above system, stir until it is completely dissolved, and obtain a clear and transparent electrolyte , the electrolyte constitutes a dual electrolyte system with greatly enhanced ionic conductivity, which improves the charge transfer efficiency of the entire circuit;

Step 2: Cut the carbon paper into a rectangle of 1cm×5cm as the substrate, put it into a mixture system of acetone:water = 1:1 and ultrasonically clean it for 3 hours, then clean it with deionized water for 3 hours, and dry it in an oven at 60°C for 6 hours , take out the spare;

Step 3: Mix the precursor powder and PVDF aqueous solution in a certain volume of deionized water, the ratio of the two is 9:1, and the total weight is 10 mg. Put it into an ultrasonic instrument and mix it for 1 hour. Drop the mixed system in this step with a dropper On the carbon paper obtained in step 2, the coating area is controlled at about 1cm×1cm to obtain a working electrode;

Step 4: Insert the working electrode, counter electrode and reference electrode into the electrolyte obtained in step 1, and connect the three electrodes to the electrochemical workstation of the model CHI760E. The workstation is controlled by a computer, and the three-electrode electrochemical etching system The construction enables a better visualization of the reaction conditions, setting the voltage constant and controllable relative to the reference electrode, and at the same time, placing magnetons in the electrolyte, placing the electrolytic cell with the electrolyte on a heated stirrer, The rotation speed was maintained at 250rpm, and the temperature was kept at a standard state temperature of 25 degrees; firstly, a cyclic voltammetry scan was performed to determine the voltage range of the current step, and then the i-t function was used on the operation interface of the electrochemical workstation to apply a constant voltage of 0.9V. Bubbles appear continuously on the electrode, indicating that the reaction process begins, and the reaction time is set to 12h;

Step 5: After the reaction is completed, soak the working electrode in a 100mL beaker filled with 50mL deionized water, perform ultrasonic treatment for 30min at a power of 100W, vacuum filter the liquid, collect the precipitate on the filter membrane and place it in a 60 After vacuum drying at °C for 12 hours, powder was obtained after drying, which was collected to obtain a two-dimensional material.

Preferably, the active substance is a substance containing an active ligand with a high stability constant after being combined with the target extraction element.

Preferably, the active substance is EDTA-2Na or sodium citrate, and the scientific and rational selection of the active substance in the electrolyte can reduce the reaction barrier to a certain extent.

Preferably, the strong electrolyte is NaCl particles.

Preferably, the precursor is MAX material and MAB material, and the MAX material includes but not limited to Ti ₃ AlC ₂ , Nb ₄ AlC ₃ , Mo ₂ Ga ₂ C, Mo ₂ TiAlC ₂ , Ti ₂ AlC or V ₂ AlC , the MAB material includes but not limited to Mo ₂ AlB ₂ , Cr ₂ AlB ₂ or MnAlB ₂ .

Preferably, the counter electrode is a highly conductive graphite rod, and the reference electrode is an Ag/AgCl electrode filled with 3M KCl solution.

A detection method for a two-dimensional material prepared by electrochemical etching based on coordination chemistry, comprising the following steps:

Step 1: Turn on the field emission scanning electron microscope and preheat for 30 minutes;

Step 2: Adhere the conductive adhesive on the sample stage, apply the precursor and the obtained powder on the conductive adhesive with a cotton swab, blow off the excess powder with a gas purification bottle, put the sample stage into the vacuum chamber of the field emission scanning electron microscope, After evacuating for 15 minutes, the surface morphology of the sample was observed with a focused electron beam.

Step 3: Carry out energy spectrum scanning on the precursor and the two-dimensional material, and obtain the relative content of each element of the two-dimensional material.

The beneficial effects of the present invention are:

1. The method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry provided by the present invention is green, safe, and efficient. The reagents used are harmless to the human body and the environment, and have obvious etching effects on target materials.

2. The method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry provided by the present invention is universal in theory. Under the premise of conforming to objective laws, select a suitable complex as the active substance of the electrolyte, and then Complete etching of most materials.

3. The method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry provided by the present invention, compared with the existing electrochemical etching system, has a clearer explanation of the mechanism, and has great guiding significance for the selection of electrolytes, and the operation It is simple, easy to implement, high in efficiency, and suitable for large-scale industrial production and application.

Description of drawings:

Fig. 1 is the schematic diagram of the electrochemical etching device based on coordination chemistry of the present invention;

2 is a schematic diagram of the principle of an electrochemical etching machine based on coordination chemistry in Embodiment 1 of the present invention;

Fig. 3 is the cyclic voltammetry curve in different electrolytes in the embodiment of the present invention;

Fig. 4 is a scanning electron microscope picture of the precursor and the two-dimensional material in the embodiment of the present invention;

Figure 5 is the content of each element in the precursor in Example 1 of the present invention;

Fig. 6 shows the content of each element in the two-dimensional material prepared in Example 1 of the present invention.

In the drawings: 1. Counter electrode; 2. Working electrode; 3. Reference electrode; 4. Electrolytic cell; 5. Electrochemical workstation; 6. Computer.

Detailed ways:

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the invention. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "or/and" includes any and all combinations of one or more of the associated listed items.

Example 1

A method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry, comprising the steps of:

Step 1: First add 5.4g of EDTA-2Na powder to a certain volume of deionized water, stir it under 100W power to make it fully dissolved, then add water to control the total volume at 80mL, and then add a certain amount of 4.6gNaCl particles to the above system , stirred until it is completely dissolved to obtain a clear and transparent electrolyte;

Step 2: Cut the carbon paper into a rectangle of 1cm×5cm as the substrate, put it into a mixture system of acetone:water = 1:1 and ultrasonically clean it for 3 hours, then clean it with deionized water for 3 hours, and dry it in an oven at 60°C for 6 hours , take out the spare;

Step 3: Mix the precursor Ti ₃ AlC ₂ powder and PVDF aqueous solution in 0.5mL deionized water, the ratio of the two is 9:1, and the total weight is 10mg, put it into an ultrasonic instrument and mix for 1h, and use the mixed system in this step The dropper was dropped on the carbon paper obtained in step 2, and the coating area was controlled at about 1cm×1cm to obtain the working electrode 2;

Step 4: Insert the working electrode 2, the counter electrode 1 and the reference electrode 3 into the electrolyte obtained in step 1, and connect the three electrodes to the electrochemical workstation 5 of the model CHI760E, which is controlled by the computer 6, and at the same time , put the magneton into the electrolyte, place the electrolytic cell 4 equipped with the electrolyte on the stirrer with heating, maintain the rotating speed at 250rpm, and keep the temperature at 25 degrees in the standard state; Step voltage range, then use the i-t function on the operation interface of the electrochemical workstation 5, apply a constant voltage of 0.9V, it can be found that there are bubbles constantly appearing on the counter electrode 1, indicating that the reaction process has begun, and the reaction time is set to 12h;

Step 5: After the reaction is completed, soak the working electrode 2 in a 100mL beaker filled with 50mL deionized water, perform ultrasonic treatment for 30min at a power of 100W, vacuum filter the liquid, collect the precipitate on the filter membrane and place it in a Vacuum drying at 60° C. for 12 hours, and powder was obtained after drying, which was collected to obtain a two-dimensional material.

A detection method for a two-dimensional material prepared by electrochemical etching based on coordination chemistry, comprising the following steps:

Step 1: Turn on the field emission scanning electron microscope and preheat for 30 minutes;

Step 2: Adhere the conductive adhesive on the sample stage, apply the precursor and the obtained powder on the conductive adhesive with a cotton swab, blow off the excess powder with a gas purification bottle, put the sample stage into the vacuum chamber of the field emission scanning electron microscope, After evacuating for 15 minutes, the surface morphology of the sample was observed with a focused electron beam.

Step 3: Carry out energy spectrum scanning on the precursor and the two-dimensional material, and obtain the relative content of each element of the two-dimensional material.

In terms of working principle, a certain voltage is applied in the electrolyte solution containing only NaCl to make the whole system start to react, which should be the reaction of electrolysis of water in essence: 2NaCl+2H ₂ O=Cl ₂ +2NaOH+H ₂ , the cathode gets H ₂ , the anode gets Cl ₂ . Essentially after the introduction of the precursors, another competing reaction occurs at the anode: Me=M+, and this reaction takes precedence over the reaction to obtain _Cl2 . The reason for this result is due to the difference between the two standard electrode potentials. In the whole system, the reaction of the cathode is the reduction reaction of H ₂ O: 2H ₂ O+2e=2OH ^- +H ₂ , there is no doubt (because in the whole system except water, only Na+ can get electrons in the cathode, this ion electrons will get metal Na, and even a small amount of this metal will exotherm violently in water, and even explode, which obviously did not happen). However, there are two possible oxidation reactions at the anode: Me=M+ and 2Cl ^- -2e=Cl ₂ , and the species with strong reducibility is preferentially oxidized, and the corresponding electric pair is the standard electrode of M+/M and Cl ₂ /Cl- The potentials are xV (x<0) and 1.36V, respectively. At the same time, according to the application analysis of the standard electrode potential of the pair where the redox reaction occurs: the smaller the standard electrode potential, the stronger the reducibility of the reducing species in the pair. It shows that the reducibility of M is stronger, and the oxidation reaction of electron loss occurs preferentially. However, due to the limitation of the cathode reaction, the system is essentially a water electrolysis reaction. In theory, the applied voltage should reach its decomposition voltage of 1.23V to make the reaction continue. In fact, we can drive the reaction by applying a voltage less than 1.23V The reason for the continuation of the applied potential is that the formation of the M-EDTA complex lowers the reaction barrier and pulls the reaction to the direction of the product. All in all, the sequence of expected reactions in this system conforms to the change rule of the standard electrode potential, and the formation of coordination compounds in the product reduces the reaction barrier and promotes the reaction, and finally the electrochemical etching occurs efficiently.

As shown in Figure 3, the curve obtained by cyclic voltammetry scanning of the working electrode 2 can be seen intuitively that the electrolytic cell 4 system containing the active material EDTA-2Na has a larger current step at 0.8V, and does not The NaCl electrolytic cell 4 system containing active substances has a step lag and a small change range, indicating that the addition of EDTA-2Na active substances and the formation of Al-EDTA complexes have reduced the reaction barrier to a certain extent; it can be clearly seen from Figure 4 It is seen that the dense packing of the precursors is broken after the electrochemical reaction, and the interlayer spacing is opened. In Fig. 5 and Fig. 6, the content of Al atoms dropped sharply by more than 50%, indicating that the target element was successfully extracted and the material was successfully etched. To sum up, by scientifically selecting the appropriate active material, the reaction barrier can be significantly reduced, the reaction can be promoted, the green and efficient etching of the target precursor can be achieved, and the final target material can be obtained.

Example 2

A method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry, comprising the steps of:

Step 1: First add 5.4g of EDTA-2Na powder to a certain volume of deionized water, stir it under 100W power to make it fully dissolved, then add water to control the total volume at 80mL, and then add a certain amount of 4.6gNaCl particles to the above system , stirred until it is completely dissolved to obtain a clear and transparent electrolyte;

Step 2: Cut the carbon paper into a rectangle of 1cm×5cm as the substrate, put it into a mixture system of acetone:water = 1:1 and ultrasonically clean it for 3 hours, then clean it with deionized water for 3 hours, and dry it in an oven at 60°C for 6 hours , take out the spare;

Step 3: Mix the precursor Nb ₄ AlC ₃ powder and PVDF aqueous solution in 0.5mL deionized water, the ratio of the two is 9:1, and the total weight is 10mg, put it in an ultrasonic instrument and mix for 1h, and use the mixed system in this step The dropper was dropped on the carbon paper obtained in step 2, and the coating area was controlled at about 1cm×1cm to obtain the working electrode 2;

Step 4: Insert the working electrode 2, the counter electrode 1 and the reference electrode 3 into the electrolyte obtained in step 1, and connect the three electrodes to the electrochemical workstation 5 of the model CHI760E, which is controlled by the computer 6, and at the same time , put the magneton into the electrolyte, place the electrolytic cell 4 equipped with the electrolyte on the stirrer with heating, maintain the rotating speed at 250rpm, and keep the temperature at 25 degrees in the standard state; Step voltage range, then use the i-t function on the operation interface of the electrochemical workstation 5, apply a constant voltage of 1V, it can be found that there are bubbles constantly appearing on the counter electrode 1, indicating that the reaction process has begun, and the reaction time is set to 12h;

Step 5: After the reaction is completed, soak the working electrode 2 in a 100mL beaker filled with 50mL deionized water, perform ultrasonic treatment for 30min at 100W power, vacuum filter the liquid, collect the precipitate on the filter membrane and place it in Vacuum-dried at 60°C for 12 hours, collected, dried and powdered to obtain a two-dimensional material.

Example 3

A method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry, comprising the steps of:

Step 1: First add 5.4g of EDTA-2Na powder to a certain volume of deionized water, stir it under 100W power to make it fully dissolved, then add water to control the total volume at 80mL, and then add a certain amount of 4.6gNaCl particles to the above system , stirred until it is completely dissolved to obtain a clear and transparent electrolyte;

Step 2: Cut the carbon paper into a rectangle of 1cm×5cm as the substrate, put it into a mixture system of acetone:water = 1:1 and ultrasonically clean it for 3 hours, then clean it with deionized water for 3 hours, and dry it in an oven at 60°C for 6 hours , take out the spare;

Step 3: Mix the precursor Mo ₂ Ga ₂ C powder and PVDF aqueous solution in 0.5 mL deionized water, the ratio of the two is 9:1, and the total weight is 10 mg. Put it into an ultrasonic instrument and mix for 1 hour. The mixed system in this step Use a dropper to drop on the carbon paper obtained in step 2, and control the coating area to about 1cm×1cm to obtain the working electrode 2;

Step 4: Insert the working electrode 2, the counter electrode 1 and the reference electrode 3 into the electrolyte obtained in step 1, and connect the three electrodes to the electrochemical workstation 5 of the model CHI760E, which is controlled by the computer 6, and at the same time , put the magneton into the electrolyte, place the electrolytic cell 4 equipped with the electrolyte on the stirrer with heating, maintain the rotating speed at 250rpm, and keep the temperature at 25 degrees in the standard state; Step voltage range, then use the i-t function on the operation interface of the electrochemical workstation 5, apply a constant voltage of 1V, it can be found that there are bubbles constantly appearing on the counter electrode 1, indicating that the reaction process has begun, and the reaction time is set to 12h;

Step 5: After the reaction is completed, soak the working electrode 2 in a 100mL beaker filled with 50mL deionized water, perform ultrasonic treatment for 30min at a power of 100W, vacuum filter the liquid, collect the precipitate on the filter membrane and place it in a Vacuum-dried at 60°C for 12 hours, collected, dried and powdered to obtain a two-dimensional material.

Example 4

A method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry, comprising the steps of:

Step 1: First add 5.4g of EDTA-2Na powder to a certain volume of deionized water, stir it under 100W power to make it fully dissolved, then add water to control the total volume at 80mL, and then add a certain amount of 4.6gNaCl particles to the above system , stirred until it is completely dissolved to obtain a clear and transparent electrolyte;

Step 2: Cut the carbon paper into a rectangle of 1cm×5cm as the substrate, put it into a mixture system of acetone:water = 1:1 and ultrasonically clean it for 3 hours, then clean it with deionized water for 3 hours, and dry it in an oven at 60°C for 6 hours , take out the spare;

Step 3: Mix the precursor Mo ₂ TiAlC ₂ powder and PVDF aqueous solution in 0.5mL deionized water, the ratio of the two is 9:1, and the total weight is 10mg. Put it into an ultrasonic instrument and mix it for 1h. Use the mixed system in this step The dropper was dropped on the carbon paper obtained in step 2, and the coating area was controlled at about 1cm×1cm to obtain the working electrode 2;

Step 4: Insert the working electrode 2, the counter electrode 1 and the reference electrode 3 into the electrolyte obtained in step 1, and connect the three electrodes to the electrochemical workstation 5 of the model CHI760E, which is controlled by the computer 6, and at the same time , put the magneton into the electrolyte, place the electrolytic cell 4 equipped with the electrolyte on the stirrer with heating, maintain the rotating speed at 250rpm, and keep the temperature at 25 degrees in the standard state; Step voltage range, then use the i-t function on the operation interface of the electrochemical workstation 5, apply a constant voltage of 1V, it can be found that there are bubbles constantly appearing on the counter electrode 1, indicating that the reaction process has begun, and the reaction time is set to 12h;

Step 5: After the reaction is completed, soak the working electrode 2 in a 100mL beaker filled with 50mL deionized water, perform ultrasonic treatment for 30min at a power of 100W, vacuum filter the liquid, collect the precipitate on the filter membrane and place it in a Vacuum-dried at 60°C for 12 hours, collected, dried and powdered to obtain a two-dimensional material.

Example 5

A method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry, comprising the steps of:

Step 1: First add 5.4g of EDTA-2Na powder to a certain volume of deionized water, stir it under 100W power to make it fully dissolved, then add water to control the total volume at 80mL, and then add a certain amount of 4.6gNaCl particles to the above system , stirred until it is completely dissolved to obtain a clear and transparent electrolyte;

Step 2: Cut the carbon paper into a rectangle of 1cm×5cm as the substrate, put it into a mixture system of acetone:water = 1:1 and ultrasonically clean it for 3 hours, then clean it with deionized water for 3 hours, and dry it in an oven at 60°C for 6 hours , take out the spare;

Step 3: Mix the precursor Ti ₂ AlC powder and PVDF aqueous solution in 0.5mL deionized water, the ratio of the two is 9:1, and the total weight is 10mg. Put it into an ultrasonic instrument and mix for 1h. The tube is dropped on the carbon paper obtained in step 2, and the coating area is controlled at about 1cm×1cm to obtain the working electrode 2;

Step 4: Insert the working electrode 2, the counter electrode 1 and the reference electrode 3 into the electrolyte obtained in step 1, and connect the three electrodes to the electrochemical workstation 5 of the model CHI760E, which is controlled by the computer 6, and at the same time , put the magneton into the electrolyte, place the electrolytic cell 4 equipped with the electrolyte on the stirrer with heating, maintain the rotating speed at 250rpm, and keep the temperature at 25 degrees in the standard state; Step voltage range, then use the i-t function on the operation interface of the electrochemical workstation 5, apply a constant voltage of 1V, it can be found that there are bubbles constantly appearing on the counter electrode 1, indicating that the reaction process has begun, and the reaction time is set to 12h;

Step 5: After the reaction is completed, soak the working electrode 2 in a 100mL beaker filled with 50mL deionized water, perform ultrasonic treatment for 30min at a power of 100W, vacuum filter the liquid, collect the precipitate on the filter membrane and place it in a Vacuum-dried at 60°C for 12 hours, collected, dried and powdered to obtain a two-dimensional material.

Example 6

A method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry, comprising the steps of:

Step 1: First add 5.4g of EDTA-2Na powder to a certain volume of deionized water, stir it under 100W power to make it fully dissolved, then add water to control the total volume at 80mL, and then add a certain amount of 4.6gNaCl particles to the above system , stirred until it is completely dissolved to obtain a clear and transparent electrolyte;

Step 2: Cut the carbon paper into a rectangle of 1cm×5cm as the substrate, put it into a mixture system of acetone:water = 1:1 and ultrasonically clean it for 3 hours, then clean it with deionized water for 3 hours, and dry it in an oven at 60°C for 6 hours , take out the spare;

Step 3: Mix the precursor Mo ₂ AlB ₂ powder and PVDF aqueous solution in 0.5mL deionized water, the ratio of the two is 9:1, and the total weight is 10mg. Put it into an ultrasonic instrument and mix it for 1h. Use the mixed system in this step The dropper was dropped on the carbon paper obtained in step 2, and the coating area was controlled at about 1cm×1cm to obtain the working electrode 2;

Step 4: Insert the working electrode 2, the counter electrode 1 and the reference electrode 3 into the electrolyte obtained in step 1, and connect the three electrodes to the electrochemical workstation 5 of the model CHI760E, which is controlled by the computer 6, and at the same time , put the magneton into the electrolyte, place the electrolytic cell 4 equipped with the electrolyte on the stirrer with heating, maintain the rotating speed at 250rpm, and keep the temperature at 25 degrees in the standard state; Step voltage range, then use the i-t function on the operation interface of the electrochemical workstation 5, apply a constant voltage of 1V, it can be found that there are bubbles constantly appearing on the counter electrode 1, indicating that the reaction process has begun, and the reaction time is set to 12h;

Step 5: After the reaction is completed, soak the working electrode 2 in a container filled with 50mL deionized water.

In a 100mL beaker, ultrasonic treatment was performed at a power of 100W for 30min, the liquid was vacuum filtered, and the precipitate on the filter membrane was collected and dried in vacuum at 60°C for 12h, collected, dried and powdered to obtain a two-dimensional material.

Example 7

A method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry, comprising the steps of:

Step 1: First add 5.4g of EDTA-2Na powder to a certain volume of deionized water, stir it under 100W power to make it fully dissolved, then add water to control the total volume at 80mL, and then add a certain amount of 4.6gNaCl particles to the above system , stirred until it is completely dissolved to obtain a clear and transparent electrolyte;

Step 2: Cut the carbon paper into a rectangle of 1cm×5cm as the substrate, put it into a mixture system of acetone:water = 1:1 and ultrasonically clean it for 3 hours, then clean it with deionized water for 3 hours, and dry it in an oven at 60°C for 6 hours , take out the spare;

Step 3: Mix the precursor Cr ₂ AlB ₂ powder and PVDF aqueous solution in 0.5mL deionized water, the ratio of the two is 9:1, and the total weight is 10mg, put it into an ultrasonic instrument and mix for 1h, and use the mixed system in this step The dropper was dropped on the carbon paper obtained in step 2, and the coating area was controlled at about 1cm×1cm to obtain the working electrode 2;

Step 4: Insert the working electrode 2, the counter electrode 1 and the reference electrode 3 into the electrolyte obtained in step 1, and connect the three electrodes to the electrochemical workstation 5 of the model CHI760E, which is controlled by the computer 6, and at the same time , put the magneton into the electrolyte, place the electrolytic cell 4 equipped with the electrolyte on the stirrer with heating, maintain the rotating speed at 250rpm, and keep the temperature at 25 degrees in the standard state; Step voltage range, then use the i-t function on the operation interface of the electrochemical workstation 5, apply a constant voltage of 1V, it can be found that there are bubbles constantly appearing on the counter electrode 1, indicating that the reaction process has begun, and the reaction time is set to 12h;

Step 5: After the reaction is completed, soak the working electrode 2 in a 100mL beaker filled with 50mL deionized water, perform ultrasonic treatment for 30min at 100W power, vacuum filter the liquid, collect the precipitate on the filter membrane and place it in Vacuum-dried at 60°C for 12 hours, collected, dried and powdered to obtain a two-dimensional material.

Example 8

A method for preparing two-dimensional materials by electrochemical etching based on coordination chemistry, comprising the steps of:

Step 1: First add 5.4g of EDTA-2Na powder to a certain volume of deionized water, stir it under 100W power to make it fully dissolved, then add water to control the total volume at 80mL, and then add a certain amount of 4.6gNaCl particles to the above system , stirred until it is completely dissolved to obtain a clear and transparent electrolyte;

Step 2: Cut the carbon paper into a rectangle of 1cm×5cm as the substrate, put it into a mixture system of acetone:water = 1:1 and ultrasonically clean it for 3 hours, then clean it with deionized water for 3 hours, and dry it in an oven at 60°C for 6 hours , take out the spare;

Step 3: Mix the precursor MnAlB ₂ powder and PVDF aqueous solution in 0.5mL deionized water, the ratio of the two is 9:1, and the total weight is 10mg. Put it in an ultrasonic instrument and mix it for 1h. Use a dropper to mix the mixed system in this step. Drop it on the carbon paper obtained in step 2, control the coating area to about 1cm×1cm, and obtain the working electrode 2;

Step 4: Insert the working electrode 2, the counter electrode 1 and the reference electrode 3 into the electrolyte obtained in step 1, and connect the three electrodes to the electrochemical workstation 5 of the model CHI760E, which is controlled by the computer 6, and at the same time , put the magneton into the electrolyte, place the electrolytic cell 4 equipped with the electrolyte on the stirrer with heating, maintain the rotating speed at 250rpm, and keep the temperature at 25 degrees in the standard state; Step voltage range, then use the i-t function on the operation interface of the electrochemical workstation 5, apply a constant voltage of 1V, it can be found that there are bubbles appearing continuously on the counter electrode 1, indicating that the reaction process has begun, and the reaction time is set to 12h;

Step 5: After the reaction is completed, soak the working electrode 2 in a 100mL beaker filled with 50mL deionized water, perform ultrasonic treatment for 30min at 100W power, vacuum filter the liquid, collect the precipitate on the filter membrane and place it in Vacuum-dried at 60°C for 12 hours, collected, dried and powdered to obtain a two-dimensional material.

The above is only used to understand the method and core idea of the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements and modifications can be made to the present invention without departing from the principles of the present invention. These improvements and modifications also fall within the protection scope of the rights of the present invention.

Claims (2)

1. The method for preparing the two-dimensional material by electrochemical etching based on coordination chemistry is characterized by comprising the following steps of:

step one: firstly adding active substances into a certain volume of deionized water, wherein the active substances are substances containing active ligands and having high stability constants after being combined with target extraction elements; the active substance is EDTA-2Na, the active substance is fully dissolved by ultrasonic stirring under the power of 100W, and then a certain amount of strong electrolyte which is NaCl particles is added into the system; stirring until the electrolyte is completely dissolved to obtain clear and transparent electrolyte;

step two: cutting carbon paper into a rectangle of 1cm×5cm as a substrate, and adding acetone: water = 1:1, ultrasonically cleaning the mixed system for 3 hours by deionized water for 3 hours, drying the mixed system in an oven at 60 ℃ for 6 hours, and taking out the mixed system for later use;

step three: mixing the precursor powder and the PVDF aqueous solution in a certain volume of deionized water in a ratio of 9:1, 10mg of total weight, putting the mixture into an ultrasonic instrument, mixing for 1h, dripping the mixed system obtained in the step on the carbon paper obtained in the step two by using a dropper, controlling the coating area to be about 1cm multiplied by 1cm to obtain a working electrode, wherein the precursor is MAX material or MAB material, and the MAX material is Ti ₃ AlC ₂ 、Nb ₄ AlC ₃ 、Mo ₂ Ga ₂ C、Mo ₂ TiAlC ₂ 、Ti ₂ AlC or V ₂ AlC, the MAB material is Mo ₂ AlB ₂ 、Cr ₂ AlB ₂ Or MnAlB ₂ ；

Step four: inserting a working electrode, a counter electrode and a reference electrode into the electrolyte obtained in the first step, connecting the three electrodes with an electrochemical workstation with the model of CHI760E, controlling the workstation by a computer, simultaneously, putting a magneton into the electrolyte, placing an electrolytic cell filled with the electrolyte on a stirrer with heating, maintaining the rotating speed at 250rpm, and maintaining the temperature at a standard state temperature of 25 ℃; firstly, cyclic voltammetry scanning is carried out, the voltage range of a current step is determined, then an i-t function is used at an operation interface of an electrochemical workstation, a constant voltage of 0.9V is applied, bubbles can be found to appear on a counter electrode continuously, the beginning of a reaction process is indicated, and the reaction time is set to be 12 hours;

step five: after the reaction is completed, the working electrode is soaked in a 100mL beaker containing 50mL of deionized water, ultrasonic treatment is carried out for 30min under the power of 100W, liquid is filtered in vacuum, sediment on the filter membrane is collected and placed at the temperature of 60 ℃ for vacuum drying for 12h, powder is obtained after drying, and the two-dimensional material is obtained after collection.

2. The method for preparing a two-dimensional material by electrochemical etching based on coordination chemistry according to claim 1, wherein: the counter electrode is a graphite rod with high conductivity, and the reference electrode is an Ag/AgCl electrode filled with 3M KCl solution.

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