Dimeric metal phthalocyanine catalyst for acidic electrocatalysis of carbon dioxide as well as preparation method and application of dimeric metal phthalocyanine catalyst

Abstract

The invention provides a dimeric metal phthalocyanine catalyst for acidic electrocatalysis of carbon dioxide and a preparation method and application thereof. According to the catalyst, non-noble metal phthalocyanine is used as an active center, and a dimerization structure (MPc = MPc) is constructed through a copolymerization reaction of phthalonitrile and tetracyanobenzene. The preparation method comprises the following steps: dissolving a sulfuric acid metal salt, phthalonitrile, tetracyanobenzene and DBU in ethylene glycol, carrying out ultrasonic dispersion, carrying out an oil bath reaction for a certain time, and carrying out centrifugal washing and vacuum drying to obtain the product. The catalyst optimizes electron distribution through a dimerization structure, effectively inhibits a hydrogen evolution reaction in an acidic electrolyte, and still keeps 81% of CO Faraday efficiency at a high current density of 300 mA cm <-2 >, and the CO Faraday efficiency can reach 97% at a high current density of 100 mA cm <-2 >. The technology provides a novel non-noble metal solution for efficient electrocatalysis of CO2 reduction in an acidic system.

Description

Technical Field

[0001] This application relates to the field of electrocatalytic technology, and particularly to a bimetallic phthalocyanine catalyst for acid electrocatalytic reduction of carbon dioxide, its preparation method and application. Background Art

[0002] Currently, the problem of global greenhouse gas emissions is becoming increasingly prominent. It is urgent to take effective measures to reduce carbon dioxide emissions and convert it into useful compounds to slow down the process of climate change. Electrochemical reduction of carbon dioxide can convert electrical energy into chemical energy, which is a reaction with great research value. It can reduce carbon dioxide (CO2) to a series of utilizable products such as carbon monoxide (CO), ethylene (C2H4), ethanol (C2H5OH, etc.). Compared with traditional chemical reduction reactions, electrochemical reduction of carbon dioxide can effectively utilize the surplus intermittent wind and solar power, and can regulate the molecular structure of organic compounds and change the number of carbon atoms in the products. Therefore, the electrochemical reduction of carbon dioxide technology, as a green and environmentally friendly way of carbon resource utilization, has attracted much attention.

[0003] Early studies focused on noble metal nanocatalysts (such as Au, Ag, Pd). For example, patent CN201780012345.6 discloses a nano-gold supported catalyst that can achieve 80% CO selectivity at -0.8V vs. RHE. However, the high cost and scarce resources of noble metals severely restrict their large-scale application. To solve these problems, researchers have turned to the research and development of non-noble metal catalysts. As a promising alternative material, non-noble metal phthalocyanine catalysts have attracted increasing attention.

[0004] Phthalocyanine is a class of macrocyclic organic compounds containing four pyridine or pyridine-like rings, with good stability and structural controllability. The design and synthesis of non-noble metal phthalocyanine catalysts provide new ideas for the electrocatalytic reduction of carbon dioxide. Compared with traditional noble metal catalysts, these non-noble metal phthalocyanine catalysts have lower costs, higher catalytic activities and better selectivities.

[0005] In recent years, research has shown that non-noble metal phthalocyanine catalysts exhibit remarkable performance in the carbon dioxide reduction reaction. In particular, these catalysts have higher catalytic activity compared to noble metal catalysts with a relatively small CO binding energy (such as gold, silver, palladium, etc.), thereby increasing the conversion rate of carbon dioxide. In addition, within a certain current density and potential range, non-noble metal phthalocyanine (MPc) catalysts also exhibit high CO selectivity, which means that carbon dioxide can be more effectively converted into the target product. Patent JP2023-56789A developed an axially coordinated modified CoPc catalyst (CoPc-NH2), which increased the CO Faraday efficiency to 92% by enhancing the CO2 adsorption capacity. However, existing MPc catalysts generally face severe hydrogen evolution competition reactions (HER) in acidic electrolytes, resulting in a sharp drop in the CO2 reduction efficiency and affecting the conversion efficiency. Summary of the Invention

[0006] This application is made in view of the above problems, and its purpose is to provide a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide, which can efficiently electrochemically catalyze the reduction of carbon dioxide to carbon monoxide in an acidic medium and meet the industrial requirements of high carbon conversion efficiency.

[0007] The first aspect of this application provides a preparation method of a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide, including the following steps:

[0008] Step 1, dissolve a metal salt of one of Fe, Ni, and Co in an ethylene glycol solution;

[0009] Step 2, dissolve phthalonitrile in an ethylene glycol solution;

[0010] Step 3, dissolve tetracyanobenzene in an ethylene glycol solution;

[0011] Step 4, dissolve DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) in an ethylene glycol solution;

[0012] Step 5, mix the solutions formed in Steps 1, 2, 3, and 4, and use ultrasonic-assisted solvent dispersion for mixing;

[0013] Step 6, transfer the solution formed in Step 4 to an oil bath, heat it up, and then let it cool naturally;

[0014] Step 7, centrifuge the solution generated in Step 6 using ethanol and dilute sulfuric acid, and then wash it by centrifugation with dilute sulfuric acid and water, and dry it under vacuum;

[0015] In any embodiment, Steps 1, 2, and 3 are respectively dissolved in an ethylene glycol solution and then added to Step 4 respectively; or Steps 1, 2, and 3 are jointly dissolved in an ethylene glycol solution and then added to Step 4; the metal salt is at least one non-noble metal salt among metal chlorides, sulfates, and carbonates.

[0016] In any embodiment, in Steps 1, 2, and 3, the molar ratio of the metal sulfate, phthalonitrile, and tetracyano benzene is 3:8:2; in Step 4, the volume ratio of DBU to ethylene glycol is 1:20 - 50.

[0017] In any embodiment, in Step 6, the temperature is 160 - 200 °C, the heating time is 6 - 8 h, and the heating rate is 4 - 6 °C / min.

[0018] In any embodiment, the ultrasonic power in Step 5 is 200 - 400 w and the treatment time is 1 - 2 h; in Step 7, the generated solution is added with ethanol and 0.5 M sulfuric acid with a volume ratio of 1:1, and centrifuged. The centrifugation speed is 4000 - 6000 r / min, the treatment time is 4 - 6 min, washed once with 0.5 M sulfuric acid and twice with water, and then vacuum dried for 12 - 16 h after centrifugation to recover the powder product.

[0019] The second aspect of the present application further provides a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide, which is the dimeric metal phthalocyanine catalyst obtained by using the preparation method of any one of the above.

[0020] The third aspect of the present application provides an application of a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide, and the MPc=MPc catalyst is used for preparing a gas diffusion electrode.

[0021] The addition amount of the MPc=MPc catalyst in the gas diffusion electrode is 3% - 8%.

[0022] An application of a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide, and the MPc=MPc catalyst is used for an electrocatalytic reaction.

[0023] An application of a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide, and the gas diffusion electrode prepared from the MPc=MPc catalyst is used for an acidic electrocatalytic carbon dioxide reduction reaction.

[0024] The MPc=MPc catalyst represents a dimeric metal phthalocyanine catalyst.

[0025] Compared with the prior art, the present invention has the following remarkable advantages: (1) The prepared catalyst has high CO selectivity in the acidic electrocatalytic carbon dioxide reduction reaction, effectively inhibits the hydrogen evolution reaction in an acidic electrolyte (pH = 1), and at 300 mA cm -It still maintains a CO Faradaic efficiency of 81% at a high current density and can reach 97% at 100 mA cm - 2; (1) The preparation method is environmentally friendly, green and pollution-free; (2) The dimeric non-precious metal phthalocyanine catalytic material has easily available raw materials and low cost, which is conducive to realizing industrial-scale high-current catalytic reactions; (3) The temperature conditions in the catalyst synthesis process are relatively broad, which is conducive to industrial production and the realization of industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A model diagram of a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide of the present invention;

[0027] Figure 2 A synthesis route diagram of a preparation method of a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide of the present invention;

[0028] Figure 3 A process flow diagram of the preparation of a gas diffusion electrode provided by Examples 1, 2, and 3 of the present invention;

[0029] Figure 4 A reaction performance diagram provided by Example 1 of the present invention;

[0030] Figure 5 Reaction performance diagrams provided by Examples 1, 2, and 3 of the present invention;

[0031] Figure 6 Reaction performance diagrams provided by Example 1 and Comparative Examples 1 and 2 of the present invention.

[0032] Figure 7 Reaction performance diagrams provided by Example 1 and Comparative Examples 3, 4, and 5 of the present invention.

[0033] Figure 8 Reaction performance diagrams provided by Example 1 and Comparative Examples 6 and 7 of the present invention.

[0034] Figure 9 Reaction performance diagrams provided by Example 1 and Comparative Examples 8 and 9 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] Hereinafter, embodiments of a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide of the present application will be specifically disclosed with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0036] The "ranges" disclosed in this application are defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the specific range. The ranges defined in this way can include or exclude the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In this application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0037] If there is no special instruction, all the embodiments and optional embodiments of this application can be combined with each other to form a new technical solution.

[0038] If there is no special instruction, all the technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0039] If there is no special instruction, all the steps of this application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0040] If there is no special instruction, the "including" and "comprising" mentioned in this application mean open-ended, and can also be closed-ended. For example, the "including" and "comprising" can mean that other components not listed can also be included or comprised, or can only include or comprise the listed components.

[0041] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0042] According to the research on current electrolytes, the electrolytes used in the electrocatalytic CO2 reduction technology at room temperature are mainly divided into alkaline solutions (such as potassium hydroxide solution) and near-neutral solutions (such as potassium bicarbonate solution). However, in alkaline solutions, CO2 reacts with the base to produce carbonates, etc., which not only greatly reduces its utilization efficiency but also consumes a large amount of alkali solution. Therefore, alkaline electrolysis is not suitable for large-scale production. In near-neutral electrolytes, the electrolyte can be recycled, but the CO2 utilization efficiency is still no more than 50%, and the internal resistance of near-neutral electrolytes is relatively high, and the overpotential of the oxygen generation reaction at the anode is too high, resulting in a high total cell voltage of the electrolytic cell and low energy utilization efficiency.

[0043] If a strong acidic solution is used as the electrolyte, the theoretical utilization efficiency of CO2 can reach 100%, and the strong acidic electrolyte can be recycled, with a low resistance and a low overpotential for the oxygen generation reaction at the anode. Under acidic conditions, the solubility of carbon dioxide increases, and at the same time, the activity of the catalyst will also be enhanced, thus promoting the reaction. Using a strong acidic electrolyte is expected to improve the energy utilization efficiency of the entire electrolysis process.

[0044] However, for strong acidic electrolytes, there is a problem that hydrogen ions (H + ) are more easily reduced than CO2, making the hydrogen evolution reaction the main reaction occurring at the cathode in strong acidic electrolytes, and the Faraday efficiency of CO2 reduction is extremely low. Therefore, the purpose of this application is to design a CO2 electroreduction catalyst that can inhibit the hydrogen evolution reaction under acidic conditions.

[0045] A preparation method of a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide includes the following steps:

[0046] Step 1, dissolve a metal salt of one of Fe, Ni, and Co in an ethylene glycol solution;

[0047] Step 2, dissolve phthalonitrile in an ethylene glycol solution;

[0048] Step 3, dissolve tetracyanobenzene in an ethylene glycol solution;

[0049] Step 4, dissolve DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) in an ethylene glycol solution;

[0050] Step 5: Mix the solutions formed in Steps 1, 2, 3, and 4, and use ultrasonic-assisted solvent dispersion for mixing;

[0051] Step 6: Transfer the solution formed in Step 4 to an oil bath, heat it up, and then let it cool naturally;

[0052] Step 7: Centrifuge the solution generated in Step 6 using ethanol and dilute sulfuric acid, then wash it by centrifugation with dilute sulfuric acid and water, and dry it under vacuum;

[0053] In some embodiments, Steps 1, 2, and 3 are respectively dissolved in an ethylene glycol solution and then added to Step 4 separately; or Steps 1, 2, and 3 are jointly dissolved in an ethylene glycol solution and then added to Step 4; the metal salt is at least one non-noble metal salt among metal chlorides, sulfates, and carbonates.

[0054] In some embodiments, in Steps 1, 2, and 3, the molar ratio of the metal sulfate, phthalonitrile, and tetracyano benzene is 3:8:2; in Step 4, the volume ratio of DBU to ethylene glycol is 1:20 - 50.

[0055] If the amounts of the metal sulfate, phthalonitrile, and tetracyano benzene exceed the above ratio range, the bimetallic phthalocyanine catalyst required by this application cannot be obtained. If it is too low, monomer formation will occur, and if it is too high, polymers will be formed.

[0056] If there is too much DBU, the high alkalinity of DBU will exacerbate the exothermic reaction, resulting in out-of-control local temperature. When the amount of DBU catalyst is insufficient, the activation energy of the ethylene glycol reduction reaction cannot be effectively reduced, resulting in an extended reaction time and possibly insufficient activation of intermediates, and a significant reduction in product yield.

[0057] In some embodiments, in Step 6, the temperature is 160 - 200 °C, the heating rate is 4 - 6 °C / min, and the heating time is 6 - 8 h.

[0058] If the temperature is lower than 160 °C, the decomposition rate of ethylene glycol is insufficient and the reduction efficiency is low, which may lead to the residue of metal precursors or the formation of unstable intermediate products (such as metal oxides). If it is higher than 200 °C, ethylene glycol is excessively decomposed into by-products such as acetic acid, which destroys the coordination structure of the phthalocyanine ring and leads to catalyst deactivation.

[0059] In some embodiments, in Step 5, the ultrasonic power is 200 - 400 w and the treatment time is 1 - 2 hours; in Step 7, the generated solution is added with ethanol and 0.5 M sulfuric acid with a volume ratio of 1:1, and centrifuged, the centrifugation speed is 4000 - 6000 r / min, the treatment time is 4 - 6 min, washed once with 0.5 M sulfuric acid and twice with water, and vacuum dried for 12 - 16 h after centrifugation to recover the powder product.

[0060] Too low power results in low processing efficiency and longer time; at too high power, the ratio of energy conversion to heat increases, which easily causes local overheating of the sample.

[0061] High-speed centrifugation can cause brittle particles (such as metal phthalocyanine catalysts) to break, affecting subsequent application performance. If the rotation speed is not sufficient to cause the target particles to settle, it will result in impurity residues and affect product quality.

[0062] A dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide, and a dimeric metal phthalocyanine catalyst obtained by using the preparation method of any one of the above.

[0063] An application of a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide, where the MPc=MPc catalyst is used to prepare a gas diffusion electrode.

[0064] In some embodiments, the addition amount of the MPc=MPc catalyst in the gas diffusion electrode is 3%-8%.

[0065] An application of a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide, where the MPc=MPc catalyst is used for an electrocatalytic reaction.

[0066] An application of a dimeric metal phthalocyanine catalyst for acidic electrocatalytic carbon dioxide, where the gas diffusion electrode prepared from the MPc=MPc catalyst is used for an acidic electrocatalytic carbon dioxide reduction reaction.

[0067] Examples

[0068] Hereinafter, examples of the present application will be described. The examples described below are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application. For those not specified in the examples regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0069] Example 1

[0070] Step 1, dissolve 3 mM nickel sulfate into 50 ml of ethylene glycol solution;

[0071] Step 2, dissolve 8 mM phthalonitrile into 50 ml of ethylene glycol solution;

[0072] Step 3, dissolve 2 mM tetracyano benzene into 50 ml of ethylene glycol solution;

[0073] Step 4, dissolve 1 ml of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) into 20 ml of ethylene glycol solution;

[0074] Step 5: Mix the solutions formed in Steps 1, 2, 3, and 4, and use ultrasonic-assisted solvent dispersion for mixing with a power of 400 w and a treatment time of 1 h;

[0075] Step 6: Transfer the solution formed in Step 5 to an oil bath, naturally heat it to 180 °C, carry out a constant-temperature condensation reflux reaction for 6 h, and then naturally cool it to room temperature;

[0076] Step 7: Add 50 ml of ethanol and 50 ml of 0.5 M sulfuric acid to the solution generated in Step 6, and carry out centrifugal separation at a centrifugal speed of 5000 r / min. Wash it once with 0.5 M sulfuric acid and twice with water, and then carry out vacuum drying for 12 h after centrifugation to recover the powder product;

[0077] Step 8: Place 15 mg of the powder product generated in Example 1 in a 50 ml centrifuge tube, add 15 ml of concentrated sulfuric acid, cover it and seal it with a sealing film. Stir at room temperature for 10 min with a stirrer speed of 800 r / min until there is no obvious solid on the centrifuge tube wall. Carry out low-temperature ultrasonic treatment for 30 min with an ultrasonic power of 400 w, dilute it in 150 ml of water, carry out centrifugal separation, wash it twice with water and once with methanol;

[0078] Step 9: Disperse the product of Step 1 by low-temperature ultrasonic treatment in 150 ml of methanol, introduce the protective gas argon, and carry out reflux treatment at 80 °C for 16 hours;

[0079] Step 10: After centrifuging and separating the solution of Step 2, disperse it by ultrasonic treatment in 50 ml of DMF solvent for 2 h, add 285 mg of KJ-EC600J carbon, carry out ultrasonic treatment for 30 min and then stir for 2 h. Finally, evaporate the solvent by rotary evaporation at 95 °C and dry it in a vacuum oven at 90 °C for more than 12 h to obtain a 5% NiPc = NiPc / C catalyst.

[0080] Example 2:

[0081] Step 1: Dissolve 3 mM of iron sulfate in 50 ml of ethylene glycol solution; other operations are the same as in Example 1.

[0082] Example 3:

[0083] Step 1: Dissolve 3 mM of cobalt sulfate in 50 ml of ethylene glycol solution; other operations are the same as in Example 1.

[0084] Comparative Example 1

[0085] Compared with Example 1, the differences are as follows: In Step 1, dissolve 3 mM of nickel sulfate in 50 ml of ethylene glycol solution; in Step 2, dissolve 8 mM of phthalocyanine in 50 ml of ethylene glycol solution; in Step 3, dissolve 2 mM of tetracyano benzene in 50 ml of ethylene glycol solution. Other operations are the same as in Example 1 to prepare a 5% NiPc / C monomer catalyst.

[0086] Comparative Example 2

[0087] Compared with Example 1, the differences are as follows: In Step 1, 3 mM of nickel sulfate is dissolved in 50 ml of ethylene glycol solution; in Step 2, 8 mM of phthalonitrile is dissolved in 50 ml of ethylene glycol solution; in Step 3, 2 mM of tetracyanobenzene is dissolved in 50 ml of ethylene glycol solution. Other operations are the same as those in Example 1, and a 5% PNiPc / C polycatalyst is prepared.

[0088] Comparative Example 3:

[0089] Compared with Example 1, the difference is that 735 mg of KJ-EC600J carbon is added to obtain a 2% NiPc = NiPc / C catalyst.

[0090] Comparative Example 4:

[0091] Compared with Example 1, the difference is that 135 mg of KJ-EC600J carbon is added to obtain a 10% NiPc = NiPc / C catalyst.

[0092] Comparative Example 5:

[0093] Compared with Example 1, the difference is that 85 mg of KJ-EC600J carbon is added to obtain a 15% NiPc = NiPc / C catalyst.

[0094] Comparative Example 6:

[0095] Compared with Example 1, the difference is that the ultrasonic power in Step 5 is 100 W.

[0096] Comparative Example 7:

[0097] Compared with Example 1, the difference is that the ultrasonic power in Step 5 is 600 W.

[0098] Comparative Example 8:

[0099] Compared with Example 1, the difference is that the reaction temperature in Step 6 is 120 °C.

[0100] Comparative Example 9:

[0101] Compared with Example 1, the difference is that the reaction temperature in Step 6 is 220 °C.

[0102] 8 mg of the 5% MPc = MPc / C catalysts prepared from three different metals in Examples 1, 2, and 3 were dispersed in 800 μL of isopropanol and 200 μL of aqueous solution, and ultrasonically treated at a low temperature for 1 h with an ultrasonic power of 400 W. Then, 50 μL of 5% Nafion solution was added, and ultrasonic treatment was continued for 1 h until they were uniformly dispersed to form a mixed dispersion. The carbon paper sprayed with the catalyst was placed on a heating plate, and the heating temperature was set at 80 °C. The mixed dispersion was sprayed onto the catalyst layer at a spraying flow rate of 1 mL / min, and the loading amount was 0.8 mg cm -2 , forming a modified layer, which was dried and used as a gas diffusion electrode (as shown in Figure 2 ).

[0103] Gas diffusion electrodes were prepared from the nickel phthalocyanine catalysts with different degrees of polymerization prepared in Example 1 and Comparative Examples 1 and 2 by the same method.

[0104] Gas diffusion electrodes were prepared from the NiPc = NiPc / C catalysts with different C loadings prepared in Example 1 and Comparative Examples 3, 4, and 5 by the same method.

[0105] Gas diffusion electrodes were prepared from the 5% NiPc = NiPc / C catalysts prepared in Example 1 and Comparative Examples 6 and 7 at different temperatures by the same method.

[0106] Gas diffusion electrodes were prepared from the 5% NiPc = NiPc / C catalysts prepared in Example 1 and Comparative Examples 8 and 9 at different powers by the same method.

[0107] The above gas diffusion electrode was used as the cathode (reaction electrode), and was combined with a perforated polytetrafluoroethylene thin plate, a graphite plate flow field, a Nafion 117 membrane, and a gas diffusion electrode with an iridium oxide loading of 1 mg cm -2 as the anode. A flow electrolytic cell was formed by pressing the MEA anode and cathode plates, and the gas outlet end was connected to a gas chromatograph to detect the generated gas products.

[0108] Some positive effects were achieved during the research and development or use of the embodiments of the present invention. Compared with the prior art, it has great advantages. The following content is described in combination with the data, charts, etc. of the test process.

[0109] Under the conditions that the acidic potassium sulfate electrolyte (K2SO4 concentration is 0.45 M, H2SO4 concentration is 0.05 M) was introduced into the electrolytic cell in Example 1 and humid carbon dioxide gas was introduced into the cathode, the electrocatalytic carbon dioxide reduction performance of the cathode was as shown in Figure 4 . The hydrogen evolution reaction was inhibited, and the gas diffusion electrode showed a high Faraday efficiency of carbon monoxide production in the current density range of 50 - 300 mA cm -2 , among which the Faraday efficiency of carbon monoxide production was the highest at 100 mA cm -2At a current density, the Faradaic current efficiency is 97%, and the cell voltage of the electrolytic reactor is only 2.8V, 300mA cm -2 The Faradaic current efficiency can still reach 81% at this current density, indicating that the gas diffusion electrode has good electrocatalytic carbon dioxide reduction reaction performance under acidic conditions.

[0110] The gas diffusion electrodes prepared in Examples 1, 2, and 3 were respectively subjected to electrochemical tests, and the electrocatalytic carbon dioxide reduction performance of the cathodes was compared as Figure 5 shown. From Figure 5 it can be seen that the CO Faradaic efficiency of the 5% NiPc = NiPc / C catalyst prepared in Example 1 is significantly higher than that of the 5% FePc = FePc / C catalyst and higher than that of the 5% CoPc = CoPc / C catalyst.

[0111] The gas diffusion electrodes prepared in Example 1 and Comparative Examples 1 and 2 were respectively subjected to electrochemical tests, and the electrocatalytic carbon dioxide reduction performance of the cathodes was compared as Figure 6 shown. From Figure 6 it can be seen that the CO Faradaic efficiency of the 5% NiPc = NiPc / C catalyst prepared in Example 1 is significantly higher than that of the 5% NiPc / C catalyst and higher than that of the 5% PNiPc / C catalyst.

[0112] The gas diffusion electrodes prepared in Example 1 and Comparative Examples 3, 4, and 5 were respectively subjected to electrochemical tests, and the electrocatalytic carbon dioxide reduction performance of the cathodes was compared as Figure 7 shown. From Figure 7 it can be seen that the CO Faradaic efficiency of the 5% NiPc = NiPc / C catalyst prepared in Example 1 is higher than that of the 2% NiPc = NiPc / C, 10% NiPc = NiPc / C, and 15% NiPc = NiPc / C catalysts prepared in Comparative Examples 3, 4, and 5.

[0113] The gas diffusion electrodes prepared in Example 1 and Comparative Examples 6 and 7 were respectively subjected to electrochemical tests, and the electrocatalytic carbon dioxide reduction performance of the cathodes was compared as Figure 8 shown. From Figure 8 it can be seen that the CO Faradaic efficiency of the 5% NiPc = NiPc / C catalyst prepared in Example 1 is significantly higher than that of the 5% NiPc = NiPc / C catalysts prepared in Comparative Examples 6 and 7.

[0114] The gas diffusion electrodes prepared in Example 1 and Comparative Examples 8 and 9 were respectively subjected to electrochemical tests, and the electrocatalytic carbon dioxide reduction performance of the cathodes was compared as Figure 9 shown. From Figure 9 it can be seen that the CO Faradaic efficiency of the 5% NiPc = NiPc / C catalyst prepared in Example 1 is higher than that of the 5% NiPc = NiPc / C catalysts prepared in Comparative Examples 8 and 9.

[0115] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and embodiments having the same constitution in essence as the technical idea and achieving the same effects within the scope of the technical solution of this application are all included in the technical scope of this application. In addition, within the scope of not departing from the gist of this application, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways constructed by combining some constituent elements in the embodiments are also included in the scope of this application.

Claims

1. A method for preparing a dimeric metal phthalocyanine catalyst for acidic electrocatalysis of carbon dioxide, characterized in that: The following steps are involved: Step 1, dissolving a metal salt of Fe, Ni, or Co into an ethylene glycol solution; Step 2, dissolving o-phthalonitrile in ethylene glycol solution; Step 3, dissolving tetracyanobenzene in ethylene glycol solution; Step 4, dissolving DBU in ethylene glycol solution; Step 5, mixing the solutions formed in steps 1, 2, 3 and 4, and using ultrasound to assist the solvent dispersion and mixing; Step 6, transferring the solution formed in step 4 to an oil bath, heating it, and then cooling it naturally; Step 7: centrifugally separate the solution generated in step 6 using ethanol and dilute sulfuric acid, then centrifugally wash it with dilute sulfuric acid and water, and vacuum dry it.

2. The method for preparing a dimeric metal phthalocyanine catalyst for acidic electrocatalysis of carbon dioxide according to claim 1, characterized in that: The steps 1, 2 and 3 are dissolved in ethylene glycol solution respectively and then added to step 4 respectively; or steps 1, 2 and 3 are dissolved in ethylene glycol solution together and then added to step 4; the metal salt is at least one non-precious metal salt selected from metal chlorides, sulfates and carbonates.

3. The method for preparing a dimeric metal phthalocyanine catalyst for acidic electrocatalysis of carbon dioxide according to claim 1, characterized in that: In the steps 1, 2 and 3, the molar ratio of the metal sulfate, o-phthalonitrile and tetracyanobenzene is 3:8:2; and in the step 4, the volume ratio of DBU and ethylene glycol is 1:20-50.

4. The method for preparing a dimeric metal phthalocyanine catalyst for acidic electrocatalysis of carbon dioxide according to claim 1, characterized in that: In step six, the temperature is 160-200° C., the heating rate is 4-6° C. / min, and the heating time is 6-8 h.

5. The method for preparing a dimeric metal phthalocyanine catalyst for acidic electrocatalysis of carbon dioxide according to claim 1, characterized in that: In the step 5, the ultrasonic power is 200-400w, and the treatment is for 1-2 hours; in the step 7, ethanol and 0.5M sulfuric acid in a volume ratio of 1:1 are added to the generated solution, and centrifugation is performed at a centrifugal speed of 4000-6000r / min for 4-6min, and the solution is washed once with 0.5M sulfuric acid, washed twice with water, and vacuum dried for 12-16h after centrifugation to recover the powder product.

6. The dimeric metal phthalocyanine catalyst obtained by the preparation method according to any one of claims 1 to 5.

7. Use of a dimeric metal phthalocyanine catalyst for acidic electrocatalysis of carbon dioxide, the dimeric metal phthalocyanine catalyst obtained by any one of the preparation methods of claims 1 to 5 or the dimeric metal phthalocyanine catalyst of claim 6, wherein the MPc=MPc catalyst is used to prepare a gas diffusion electrode.

8. The use of a dimeric metal phthalocyanine catalyst for acidic electrocatalysis of carbon dioxide according to claim 7, characterized in that: The amount of the MPc=MPc catalyst added to the gas diffusion electrode is 3%-8%.

9. The use of a dimeric metal phthalocyanine catalyst for acidic electrocatalysis of carbon dioxide according to claim 7 or 8, characterized in that: MPc=MPc catalyst is used for electrocatalytic reaction.

10. The use of a dimeric metal phthalocyanine catalyst for acidic electrocatalysis of carbon dioxide according to claim 9, characterized in that: The gas diffusion electrode prepared with MPc=MPc catalyst is used for acidic electrocatalytic carbon dioxide reduction reaction.

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