Porous metal / conducting polymer / carbon composite material and preparation method and application thereof

Abstract

The invention discloses a porous metal / conductive polymer / carbon composite material and a preparation method and application thereof, and relates to the technical field of electrode materials.Carbon paper is used as a substrate in a liquid-phase flowing electrolytic tank, stirring is replaced with flowing of wastewater source deposition liquid, and microbubbles are formed on the deposition face by introducing CO2 into the back face of the carbon paper, so that the porous metal / conductive polymer / carbon composite material is obtained. The conductive polymer and the porous metal are subjected to in-situ electrodeposition on the carbon paper, and the obtained porous metal / conductive polymer / carbon composite material is used as an electrode to be applied to electrocatalytic reduction of CO2; compared with a traditional slurry coating type electrode preparation method, the electrode preparation method adopted by the invention is simpler and more convenient, recycling of harmful wastewater can be realized, meanwhile, a more stable three-phase interface can be formed, and the electrocatalytic reduction process of CO2 can be promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode materials, and particularly relates to a porous metal / conductive polymer / carbon composite material, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, the concentration of greenhouse gas carbon dioxide (CO2) in the atmosphere has risen sharply, making it difficult to maintain the natural carbon balance. This not only causes global warming but also threatens the sustainable development of humanity. In addition, the rapid economic development and overexploitation of resources have made the earth's energy resources increasingly scarce, plunging the world into an energy crisis. At the same time, the demand for and production of large amounts of metals and polymer monomers such as aniline and pyrrole have also caused serious wastewater pollution. The CO2 electrocatalytic reduction (CO2ER) technology converts CO2 into high-value products, and both the metals and polymer monomers in the wastewater can be reused in CO2ER. This can not only alleviate the trend of global warming but also turn waste into treasure and generate new energy, which is an important way to achieve the recycling of CO2.

[0003] CO2ER can directly use electrical energy to establish a potential difference between two electrodes, thereby converting CO2 into value-added chemical products under mild conditions. Although the research on electrochemically reducing CO2 in aqueous media at room temperature has been widely carried out, many problems still remain and industrialization has not been achieved. Among them, the preparation of electroreduction catalysts and electrodes is the focus of research, which determines the overall efficiency and economic benefits of CO2 reduction.

[0004] In the prior art, the preparation methods disclosed for CO2 electroreduction catalytic electrodes mainly involve chemically synthesizing relevant metal catalysts, then dissolving the catalysts and binders in a solvent to form a slurry, and bonding the slurry to a substrate by spraying or drop coating. This preparation method is relatively complex, time-consuming, and the catalytic layer is prone to uneven coating and peeling, resulting in the inability to form a stable three-phase interface during the electrocatalytic reduction process and achieve high-efficiency stable operation. The traditional electrodeposition method requires first depositing a catalytic layer on a carbon paper and then transferring it to a flow electrolytic cell for use. This preparation method will deposit the target metal on both sides of the carbon paper substrate, and the directly deposited metal cannot form a porous structure, which will affect the penetration of carbon dioxide gas from the back of the carbon paper in the flow electrolytic cell and greatly increase the internal resistance, affecting the electrocatalytic efficiency. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a porous metal / conductive polymer / carbon composite material, in which carbon paper is used as a substrate in a liquid phase flow electrolytic cell, the flow of wastewater source deposition liquid is used instead of stirring, and CO2 is introduced to the back of the carbon paper to form microbubbles on the deposition surface, thereby in-situ electrodepositing conductive polymer and porous metal on the carbon paper, and the obtained porous metal / conductive polymer / carbon composite material is used as an electrode for electrocatalytic reduction of CO2. Compared with the traditional slurry coating type electrode preparation method, the electrode preparation method adopted by the present invention is simpler and more convenient, and can realize the reuse of harmful wastewater, and at the same time can form a more stable three-phase interface to promote the electrocatalytic reduction process of CO2.

[0006] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0007] One of the purposes of the present invention is to provide a method for preparing a porous metal / conductive polymer / carbon composite material, comprising the following steps:

[0008] Step 1: Preparation of electrodeposition solution

[0009] 1.1 The electrodeposition solution A is prepared by using wastewater containing conductive polymer monomers and a polymerization catalyst;

[0010] 1.2 Use wastewater containing heavy metals, complexing agent and reducing agent to prepare electrodeposition solution B;

[0011] Step 2: Assembly and deposition of liquid flow electrolytic cell

[0012] 2.1 The liquid phase flow electrolytic cell comprises a gas chamber, a cathode chamber and an anode chamber;

[0013] 2.2 Stick the carbon paper between the gas chamber and the cathode chamber with conductive tape, with the microporous layer facing the cathode chamber;

[0014] 2.3 Insert the counter electrode and the reference electrode into the anode chamber and the cathode chamber respectively, and introduce gas into the gas chamber at the same time;

[0015] 2.4 Adding electrodeposition solution A into the liquid phase flow electrolytic cell to deposit the conductive polymer on the surface of the carbon paper;

[0016] 2.5 The electrodeposition solution A is replaced with the electrodeposition solution B, and metal is deposited on the conductive polymer to obtain a porous metal / conductive polymer / carbon composite material.

[0017] The second object of the present invention is to provide a porous metal / conductive polymer / carbon composite material prepared by the above-mentioned preparation method.

[0018] A third object of the present invention is to provide the use of the aforementioned porous metal / conductive polymer / carbon composite material in the electrocatalytic reduction of CO2.

[0019] A fourth object of the present invention is to provide a method for electrocatalytic reduction of CO2 using wastewater. First, the porous metal / conductive polymer / carbon composite material is prepared by the aforementioned preparation method of the porous metal / conductive polymer / carbon composite material, and then the electrodeposition solution B is replaced with a CO2 reduction electrolyte solution for electrocatalytic reduction of CO2.

[0020] In the present invention, in a liquid-phase flow electrolytic cell, an in-situ electrodeposition method is used to first deposit a conductive polymer on carbon paper, and then deposit a metal catalytic material on the conductive polymer layer, avoiding the cumbersome and uneven problems of traditional drop coating and spraying, as well as the problem of increased internal resistance in conventional two-sided deposition. In the deposition process of the present invention, gas is introduced into the back of the carbon paper, and the in-situ generation of porous metal is controlled by the dynamic bubble template method, and the catalyst loading is uniform, stable and the morphology is uniform.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. In the present invention, in a liquid-phase flow electrolytic cell, wastewater is used to in-situ deposit a conductive polymer and a metal catalyst on carbon paper, which is not only convenient to operate, realizes single-sided deposition and the catalyst loading is more uniform, but also reduces the discharge pollution by reusing harmful wastewater.

[0023] 2. The present invention adopts the dynamic bubble template method. By introducing gas during the deposition process, the obtained catalytic material has rich pores, an increased specific surface area, more reaction sites, and improved catalytic activity.

[0024] 3. By adding conductive polymers such as polyaniline and polypyrrole, the present invention strengthens the capture of CO2 during the electrocatalytic reduction of CO2 and establishes a more stable three-phase reaction interface.

[0025] 4. The in-situ deposition for preparing electrode materials in the liquid-phase flow electrolytic cell of the present invention can be combined with the electrocatalytic reduction of CO2, and the in-situ electroreduction of CO2 can be realized only by replacing the electrolyte solution. Description of the Drawings

[0026] Figure 1 SEM image of the porous metal / conductive polymer / carbon composite material prepared in Example 1. Detailed Embodiments

[0027] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments and illustrations.

[0028] The present invention provides a method for preparing a porous metal / conductive polymer / carbon composite material, comprising the following steps:

[0029] Step 1: Preparation of the electrodeposition solution

[0030] 1.1 Prepare electrodeposition solution A by using wastewater containing conductive polymer monomers and a polymerization catalyst.

[0031] 1.2 Prepare electrodeposition solution B by using wastewater containing heavy metals, a complexing agent, and a reducing agent.

[0032] Step 2: Assembly and deposition of the liquid-phase flow electrolytic cell

[0033] 2.1 The liquid-phase flow electrolytic cell includes a gas chamber, a cathode chamber, and an anode chamber.

[0034] 2.2 Paste the carbon paper between the gas chamber and the cathode chamber with conductive tape, with the microporous layer facing the cathode chamber.

[0035] 2.3 Insert the counter electrode and the reference electrode into the anode chamber and the cathode chamber respectively, and simultaneously introduce gas into the gas chamber.

[0036] 2.4 Add electrodeposition solution A to the liquid-phase flow electrolytic cell to deposit a conductive polymer on the surface of the carbon paper.

[0037] 2.5 Replace electrodeposition solution A with electrodeposition solution B to deposit a metal on the conductive polymer, obtaining a porous metal / conductive polymer / carbon composite material.

[0038] Further, the polymerization catalyst can be a catalyst for polymer synthesis well-known in the art, including but not limited to at least one of p-toluenesulfonic acid and sodium p-toluenesulfonate.

[0039] Further, the complexing agent can be any complexing agent well-known in the art or a combination of several complexing agents. Exemplarily, the complexing agent is sodium citrate.

[0040] Further, the reducing agent can be any reducing agent well-known in the art or a combination of several reducing agents. Exemplarily, the reducing agent is urea.

[0041] Further, the wastewater containing conductive polymer monomers includes but is not limited to at least one of wastewater containing aniline, wastewater containing pyrrole, wastewater containing thiophene, and wastewater containing carbazole.

[0042] Further, the concentration of the conductive polymer monomer in electrodeposition solution A is 0.1 - 0.5 M, and the concentration of the polymerization catalyst is 0.1 - 0.7 M.

[0043] Further, the wastewater containing heavy metals includes but is not limited to at least one of wastewater containing tin and wastewater containing bismuth.

[0044] Further, the concentration of heavy metal ions in electrodeposition solution B is 0.01 - 0.05 M, and the concentration of the complexing agent is 0.05 - 0.1 M.

[0045] Further, the conductive tape is a conductive copper foil tape or a conductive aluminum foil tape.

[0046] Further, the counter electrode is a platinum counter electrode.

[0047] Further, the reference electrode is a silver / silver chloride reference electrode.

[0048] Further, the gas is carbon dioxide, and the gas flow rate is 1-10 mL / min. The size of the gas flow rate will affect the formation of microbubbles.

[0049] Further, the flow rates of the electrodeposition solution A and the electrodeposition solution B are 1-10 mL / min. Of course, the flow rates of the electrodeposition solution A and the electrodeposition solution B are not limited to this range, and the size of the flow rate will affect the utilization rate of the conductive polymer monomer in the wastewater.

[0050] Further, the deposition of the conductive polymer is carried out by cyclic voltammetry, the potential range is 0.2-1 V, the scanning rate is 0.025-0.075 mV / s, and the number of scanning cycles is 4-10 times. Of course, the voltage range, the scanning rate, and the number of scanning cycles are not limited to this range.

[0051] Further, the deposition of the metal is carried out by chronoamperometry, the current is 1-10 mA, and the deposition time is 10-30 min. Of course, the current and the deposition time are not limited to this range, and the current and the deposition time will affect the deposition amount of the metal on the conductive polymer.

[0052] The present invention provides a porous metal / conductive polymer / carbon composite material prepared by the foregoing preparation method.

[0053] The present invention provides the application of the foregoing porous metal / conductive polymer / carbon composite material in the electrocatalytic reduction of CO2. Specifically, the foregoing porous metal / conductive polymer / carbon composite material is used as a working electrode.

[0054] The present invention also provides a method for electrocatalytically reducing CO2 from wastewater. First, the porous metal / conductive polymer / carbon composite material is prepared by the foregoing preparation method of the porous metal / conductive polymer / carbon composite material, and then the electrodeposition solution B is replaced with a CO2 reduction electrolyte for electrocatalytic reduction of CO2.

[0055] Further, the electrocatalytic reduction is carried out by a current-time curve method, and the potential is -2.2 to -2.0 V.

[0056] Example 1

[0057] Step 1. Preparation of the electrodeposition solution

[0058] 1.1 Dissolve the wastewater containing aniline and p-toluenesulfonic acid in distilled water to obtain electrodeposition solution A. Among them, the concentration of aniline is 0.2 M, and the concentration of p-toluenesulfonic acid is 0.5 M.

[0059] 1.2 Add the wastewater containing tin to the sodium citrate solution, adjust the pH to 6 with 1 M sulfuric acid solution, and then add urea to obtain electrodeposition solution B. Among them, the concentration of tin ions is 0.02 M, the concentration of sodium citrate is 0.05 M, and the concentration of urea is 0.1 M.

[0060] Step 2: Assembly and deposition of the liquid-phase flow electrolytic cell

[0061] 2.1 The liquid-phase flow electrolytic cell includes a gas chamber, a cathode chamber, and an anode chamber.

[0062] 2.2 Cut the carbon paper into a square of 2×2 cm 2 and then paste the carbon paper between the gas chamber and the cathode chamber with conductive copper tape, with the microporous layer facing the cathode chamber.

[0063] 2.3 Insert the platinum counter electrode and the silver / silver chloride reference electrode into the anode chamber and the cathode chamber respectively. At the same time, introduce CO2 into the gas chamber, and the CO2 flow rate is 5 mL / min.

[0064] 2.4 Add electrodeposition solution A to the liquid-phase flow electrolytic cell, the flow rate of electrodeposition solution A is 5 mL / min, adopt cyclic voltammetry, the potential range is -0.2 to 1 V, the scanning rate is 0.025 V / s, and the number of scanning cycles is 4 circles to deposit a conductive polymer on the surface of the carbon paper.

[0065] 2.5 Replace electrodeposition solution A with electrodeposition solution B, the flow rate of electrodeposition solution B is 5 mL / min, adopt chronoamperometry, the current is 5 mA, and the deposition time is 15 min to deposit a metal on the conductive polymer to obtain a porous metal / conductive polymer / carbon composite material.

[0066] Figure 1 is the scanning electron microscope (SEM) image of the porous metal / conductive polymer / carbon composite material. From Figure 1 it can be seen that the metal and the conductive polymer are deposited relatively evenly on the carbon paper.

[0067] Step 3: Electrochemical reduction of CO2

[0068] Replace electrodeposition solution B with 1 M KOH solution, the flow rate of KOH solution is 8 mL / min, adjust the CO2 flow rate to 25 mL / min, adopt the current-time curve method, the potential is -2.1 V, and the electrolysis time is 60 min. Use an ion chromatograph to detect the formate content and calculate the Faraday efficiency.

[0069] Test results: The current density at an electrolysis potential of -2.1 V is 204 mA / cm 2 , and the Faradaic efficiency of formic acid is 90.83%.

[0070] Example 2

[0071] The operating steps of this example are the same as those of Example 1, except that: the wastewater containing the conductive polymer monomer is the wastewater containing pyrrole, the concentration of pyrrole in the electrodeposition solution A is 0.2 M, and the concentration of sodium p-toluenesulfonate is 0.1 M;

[0072] Test results: The current density at an electrolysis potential of -2.1 V is 180 mA / cm 2 , and the Faradaic efficiency of formic acid is 86.35%.

[0073] Example 3

[0074] The operating steps of this example are the same as those of Example 1, except that: the heavy metal wastewater is the wastewater containing bismuth, the concentration of bismuth ions in the electrodeposition solution B is 0.01 M, and 0.2 M nitric acid solution is used to adjust the pH.

[0075] Test results: The current density at an electrolysis potential of -2.1 V is 214 mA / cm 2 , and the Faradaic efficiency of formic acid is 84.72%.

[0076] Comparative Example 1

[0077] The operating steps of this comparative example are the same as those of Example 1, except that: the conductive polymer polyaniline is not deposited, and only metallic tin is deposited on the surface of the carbon paper.

[0078] Test results: The current density at an electrolysis potential of -2.1 V is 53 mA / cm 2 , and the Faradaic efficiency of formic acid is 42.62%.

[0079] Comparative Example 2

[0080] The operating steps of this comparative example are the same as those of Example 1, except that: instead of using wastewater as the raw material to in-situ deposit polyaniline and tin on the carbon paper, the same amount of tin is loaded on the carbon paper by the method of slurry drop coating.

[0081] Among them, the slurry is prepared from 1 mL of ethanol, 100 μL of Nafion solution and 25 mg of metallic tin.

[0082] Test results: The current density at an electrolysis potential of -2.1 V is 138 mA / cm 2 , and the Faradaic efficiency of formic acid is 67.3%.

[0083] Comparative Example 3

[0084] The operating steps of this comparative example are the same as those of Example 1, except that: instead of using wastewater as the raw material to in-situ deposit polyaniline and tin on the carbon paper, the same amount of tin is loaded on the carbon paper by a traditional double-sided deposition method.

[0085] Among them, the traditional double-sided deposition method is to carry out static deposition on the carbon paper in an H-type cell. The program of the electrochemical workstation is the constant voltage method, set to 1V, and the deposition time is 20 min.

[0086] Test results: The current density at an electrolysis potential of -2.1V is 52 mA / cm 2 , and the Faraday efficiency of formic acid is 42.54%.

[0087] In summary, the present invention uses wastewater as the raw material, and utilizes a liquid-phase flow electrolytic cell to in-situ deposit a conductive polymer and a metal catalyst on one side of the carbon paper. The obtained electrode material can be applied to the electrocatalytic reduction of CO2 and has good catalytic activity.

[0088] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a porous metal / conductive polymer / carbon composite material, characterized by comprising the following steps: Step 1, Preparation of the electrodeposition solution 1.1 Prepare electrodeposition solution A by using wastewater containing conductive polymer monomers and a polymerization catalyst; 1.2 Prepare electrodeposition solution B by using wastewater containing heavy metals, a complexing agent, and a reducing agent; Step 2: Assembly and deposition of a liquid-phase flow electrolytic cell 2.1 The liquid-phase flow electrolytic cell includes a gas chamber, a cathode chamber, and an anode chamber; 2.2 Paste carbon paper between the gas chamber and the cathode chamber with conductive tape, with the microporous layer facing the cathode chamber; 2.3 Insert the counter electrode and the reference electrode into the anode chamber and the cathode chamber respectively, and simultaneously introduce gas into the gas chamber; 2.4 Add electrodeposition solution A to the liquid-phase flow electrolytic cell and deposit a conductive polymer on the surface of the carbon paper; 2.5 Replace electrodeposition solution A with electrodeposition solution B and deposit metal on the conductive polymer to obtain a porous metal / conductive polymer / carbon composite material.

2. The preparation method according to claim 1, wherein: the polymerization catalyst is at least one of p-toluenesulfonic acid and sodium p-toluenesulfonate; Preferably, the complexing agent is sodium citrate; Preferably, the reducing agent is urea.

3. The preparation method according to claim 1, characterized in that: The wastewater containing conductive polymer monomers is at least one of wastewater containing aniline, wastewater containing pyrrole, wastewater containing thiophene, and wastewater containing carbazole; Preferably, the concentration of the conductive polymer monomer in electrodeposition solution A is 0.1 - 0.5 M, and the concentration of the polymerization catalyst is 0.1 - 0.7 M; Preferably, the wastewater containing heavy metals is at least one of wastewater containing tin and wastewater containing bismuth; Preferably, the concentration of heavy metal ions in electrodeposition solution B is 0.01 - 0.05 M, and the concentration of the complexing agent is 0.05 - 0.1 M.

4. The preparation method according to claim 1, wherein: The conductive tape is a conductive copper foil tape or a conductive aluminum foil tape; Preferably, the counter electrode is a platinum counter electrode; Preferably, the reference electrode is a silver / silver chloride reference electrode; Preferably, the gas is carbon dioxide, and the gas flow rate is 1 - 10 mL / min; Preferably, the flow rates of electrodeposition solution A and electrodeposition solution B are 1 - 10 mL / min.

5. The preparation method according to claim 1, characterized in that: The deposition of the conductive polymer is carried out by cyclic voltammetry, with a potential range of 0.2 - 1 V, a scan rate of 0.025 - 0.075 mV / s, and the number of scan cycles being 4 - 10 times.

6. The preparation method according to claim 1, characterized in that: The deposition of the metal is carried out by chronoamperometry, with a current of 1 - 10 mA and a deposition time of 10 - 30 min.

7. A porous metal / conductive polymer / carbon composite material prepared by the preparation method according to any one of claims 1 - 6.

8. Application of the porous metal / conductive polymer / carbon composite material according to claim 7 in the electrocatalytic reduction of CO2.

9. A method for electrocatalytic reduction of CO2 using wastewater, characterized in that: First, prepare a porous metal / conductive polymer / carbon composite material by using the preparation method according to any one of claims 1 - 6, and then replace electrodeposition solution B with a CO2 reduction electrolyte for the electrocatalytic reduction of CO2.

10. The method according to claim 9, wherein: The electrocatalytic reduction is carried out by the current-time curve method, with a potential of -2.2 - -2.0 V.

Images