Organometallic Complexes, Their Preparation Methods and Applications

Abstract

The present invention discloses an organometallic complex, a preparation method thereof and an application thereof. The organometallic complex includes an organic ligand and two metal ions anchored on the organic ligand. The structure of the organic ligand is as follows: The preparation method of the complex includes: 1) Mixing the organic ligand, a soluble metal salt and a solvent A to obtain a solution A; 2) Adding an antisolvent B to the solution A and washing the precipitate with a cleaning agent C to obtain the complex; wherein, the molar ratio of the organic ligand to the soluble metal salt is 1:(3.5-10). Meanwhile, the organometallic complex of the present invention is essentially a bimetallic atom complex, which not only has the characteristics of simple structure, easy characterization and analysis, and simple preparation of the ligand, but also has the advantages of strong controllability of the preparation method, simple process and low energy consumption, and is particularly suitable for use as an electrocatalyst for the recovery and utilization of carbon dioxide.

Description

Technical Field

[0001] The present invention relates to the technical field of complexes, and specifically relates to an organometallic complex, a preparation method thereof, and an application thereof. Background Art

[0002] Developing technologies for carbon dioxide recovery and utilization is not only expected to alleviate the greenhouse effect and even the energy crisis, but also has great and far-reaching significance for achieving energy conservation, emission reduction, and low-carbon economy. Compared with other carbon dioxide reduction technologies, electrocatalytic reduction has become a currently highly concerned carbon dioxide conversion path due to its advantages such as low energy consumption, simple operation, and strong controllability. Although various types of catalysts including metals, metal oxides, metal sulfides, and carbon-based materials have been developed in electrocatalytic reduction of carbon dioxide in recent years. However, on the one hand, since carbon dioxide molecules are very stable, their reduction requires a relatively high overpotential, and the reaction process is complex and the products are diverse; on the other hand, the reduction potential of carbon dioxide is close to that of water, and there is a competitive relationship between the carbon dioxide electroreduction reaction and the water reduction reaction. Therefore, the currently reported catalysts have problems such as a relatively high overpotential, low catalytic activity, and low product selectivity in electrocatalytic reduction of carbon dioxide, which greatly hinders their practical application and industrialization process.

[0003] In electrocatalytic reduction of carbon dioxide, in order to not only retain the high activity of single-atom catalysts but also achieve the synergistic effect between different metal atoms, relevant researchers have proposed a dual-atom catalyst containing two metal active sites (for example, a dual-atom catalyst containing Pd and Pt). However, the preparation method of such dual-atom catalysts for electrocatalytic CO2 reduction is generally high-temperature pyrolysis, which has problems such as many types of reagents, high preparation cost, high energy consumption, complex process, and poor preparation controllability.

[0004] Meanwhile, in order to ensure the stability and size of the catalytic components on the dual-atom catalyst, relevant researchers usually also use ligands with relatively large molecular weights and relatively complex structures (for example, phthalocyanine, porphyrin compounds) to anchor metal atoms to prepare single-atom or dual-atom catalysts. However, this catalyst preparation method also has the defects of relatively high cost and relatively complex process.

[0005] Therefore, there is an urgent need to develop an organometallic complex with a simple and controllable preparation process, low cost, relatively simple composition and structure, and high electrocatalytic carbon dioxide reduction activity, and a preparation method thereof. Summary of the Invention

[0006] In order to solve the defects of complex preparation process, high energy consumption, high cost and poor process controllability of dual-atom catalysts in the prior art, as well as the technical problems such as the difficulty in preparing dual-atom catalysts with ligands having a simple structure, one of the objectives of the present invention is to propose a preparation method that can effectively avoid using organometallic complexes prepared by high-temperature pyrolysis. Another objective of the present invention is to propose an organometallic complex and its application that has a simple structure, is convenient for characterization and synthesis, has controllable preparation, high electrocatalytic carbon dioxide reduction activity, and also maintains the advantages of the dual-atom synergistic effect.

[0007] It should be noted that in the organometallic complex provided by the present invention, the metal is in the state of metal ions, and 2 metal atoms can be obtained after the ionization of the organometallic complex. Therefore, the organometallic complex can also be called a "dual-metal atom complex".

[0008] The inventive concept of the present invention: First, 1,2-bis(2-pyridyl ethynyl)benzene is prepared from 1,2-diiodobenzene and 2-ethynylpyridine; then, 1,2-bis(2-pyridyl ethynyl)benzene is used as an organic ligand. By designing a reasonable molar ratio of 1,2-bis(2-pyridyl ethynyl)benzene to metal atoms, 2 metal ions can be successfully introduced onto the organic ligand to prepare a dual-metal atom complex. Moreover, the 2 metal atoms on the organometallic complex can be respectively anchored between the 2 pyridine nitrogens and between the 2 alkyne bonds of the organic ligand.

[0009] The technical solution adopted by the present invention is as follows:

[0010] In a first aspect, the present invention proposes an organometallic complex comprising an organic ligand and two metal ions anchored on the organic ligand, and the structure of the organic ligand is as follows:

[0011]

[0012] Specifically, in the organometallic complex of the present invention, the metal is in the state of metal ions, and 2 metal atoms can be obtained after the ionization of the organometallic complex. Therefore, the organometallic complex can also be called a "dual-metal atom complex".

[0013] Preferably, in the organometallic complex, one metal ion is anchored between the two pyridine nitrogens of the organic ligand, and the other metal ion is anchored between the two alkyne bonds of the organic ligand;

[0014] The organometallic complex has the following structural formula: Wherein, Me represents the metal.

[0015] Preferably, the metal ion is Pd 2+ 、Pt 2+One of the following.

[0016] Further preferably, the metal ion is Pd 2+ .

[0017] Preferably, the metal atom is further connected to a second ligand through coordination, and the second ligand is one or more of *Cl, *Br, *I, C≡N*, *N≡CCH3; wherein, "*" is the position where the ligand coordinates with the metal ion.

[0018] Further preferably, the metal atom is further connected to a second ligand through coordination, and the second ligand is one or more of *Cl, *Br, *I, C≡N*, *N≡CCH3; wherein, "*" is the position where the ligand coordinates with the metal ion.

[0019] In a second aspect, the present invention provides a method for preparing the organometallic complex described in the first aspect, comprising the following steps:

[0020] 1) Mix the organic ligand, soluble metal salt, and solvent A to obtain solution A;

[0021] 2) Add antisolvent B to solution A, and wash the precipitate with cleaning agent C to obtain the organometallic complex;

[0022] Wherein, the molar ratio of the organic ligand to the soluble metal salt in step 1) is 1: (3.5 - 10).

[0023] Preferably, the molar ratio of the organic ligand to the soluble metal salt in step 1) is 1: (4 - 6).

[0024] Preferably, the method for preparing the organic ligand in step 1) comprises the following steps:

[0025] Mix 1,2-diiodobenzene, 2-ethynylpyridine, and a reaction catalyst, then add ammonia water and carry out a reaction to obtain the organic ligand.

[0026] Preferably, the mass ratio of 1,2-diiodobenzene to 2-ethynylpyridine is (1 - 2): 1.

[0027] Preferably, the concentration of the ammonia water is 0.2M - 1.0M.

[0028] Specifically, 1.0M represents 1.0 mmol / L.

[0029] Preferably, the reaction catalyst includes one or two of copper iodide and dichloro-bis(triphenylphosphine)palladium.

[0030] Preferably, the method for preparing the organic ligand is carried out under a protective atmosphere at a temperature of 15 - 30 °C.

[0031] Preferably, the reaction time is 60 to 100 hours.

[0032] Preferably, the preparation method of the organic ligand further includes the steps of rotary evaporation concentration treatment, dissolution, liquid separation, water removal, separation and purification.

[0033] Preferably, the mixing in step 1) is carried out under the conditions of a temperature of 15°C to 35°C and in the dark.

[0034] Preferably, the specific manner of the mixing in step 1) is one of stirring mixing and ultrasonic mixing.

[0035] Preferably, the mixing time in step 1) is 8h to 20h.

[0036] More preferably, the mixing time in step 1) is 10h to 15h.

[0037] Preferably, the mass ratio of the organic ligand to the volume of the solvent A in step 1) is 5mg / mL to 15mg / mL.

[0038] Preferably, the soluble metal salt in step 1) is one or more of bis(acetonitrile)palladium(II) chloride, palladium(II) chloride, dichlorotetraamminepalladium(II), bis(triphenylphosphine)palladium(II) dichloride, palladium(II) bromide, palladium(II) iodide, bis(acetonitrile)dichloroplatinum(II), bis(benzonitrile)dichloroplatinum(II), platinum(II) iodide, and platinum(II) bromide.

[0039] More preferably, the soluble metal salt in step 1) is one or more of bis(acetonitrile)palladium(II) chloride, palladium(II) chloride, dichlorotetraamminepalladium(II), bis(triphenylphosphine)palladium(II) dichloride, bis(acetonitrile)dichloroplatinum(II), and bis(benzonitrile)dichloroplatinum(II).

[0040] Preferably, the solvent A in step 1) is one or more of N,N-dimethylformamide and dimethyl sulfoxide.

[0041] Preferably, the antisolvent B in step 2) is one or more of water, chloroform, isopropanol, and dichloromethane.

[0042] Preferably, the cleaning agent C in step 2) is one or more of acetone, toluene, and ethyl acetate.

[0043] Specifically, the cleaning agent in step 2) is used to wash away the excess soluble metal salt.

[0044] Preferably, the volume ratio of the solution A to the antisolvent B in step 2) is 1:(8 - 15).

[0045] Preferably, step 2) further includes a drying step.

[0046] In a third aspect, the present invention provides an application of a complex in an electrocatalytic reduction reaction, wherein the complex is the organometallic complex described in the first aspect, or an organometallic complex prepared by the preparation method described in the second aspect.

[0047] Preferably, the reduction reaction is a carbon dioxide reduction reaction.

[0048] More preferably, the reduction reaction is a reaction of reducing carbon dioxide to carbon monoxide.

[0049] Specifically, the product of the carbon dioxide reduction reaction is mainly carbon monoxide, and there is also a small amount of hydrogen.

[0050] Preferably, the product of the reduction reaction is carbon monoxide.

[0051] In a fourth aspect, the present invention provides a catalyst, which includes the above-mentioned organometallic complex and a carbon material, and the organometallic complex is loaded on the carbon material.

[0052] Specifically, the organometallic complex is loaded on the carbon material (such as carbon nanotubes) through π-π conjugation.

[0053] Preferably, the carbon material is one or more of graphene, carbon nanotubes, activated carbon, and graphdiyne.

[0054] In a fifth aspect, the present invention provides an electrode material, which includes the catalyst described in the first aspect.

[0055] Preferably, the preparation method of the electrode material includes the following steps:

[0056] Mix the metal-organic complex, solvent, and carbon material, and then add a binder to disperse to obtain a dispersion;

[0057] Drop or coat the dispersion on a conductor to obtain the electrode material.

[0058] Preferably, the mass ratio of the metal-organic complex to the carbon material is 1:(1.5 - 3.5).

[0059] Preferably, the carbon material is one or more of graphene, carbon nanotubes, activated carbon, and graphdiyne.

[0060] Preferably, the solvent is one or more of N,N-dimethylformamide and dimethyl sulfoxide.

[0061] Preferably, the ratio of the volume of the dispersion liquid to the area of the conductor is (200 - 600):1 μL / cm 2 .

[0062] Preferably, the conductor is one or more of carbon cloth, copper foil, and aluminum foil.

[0063] Preferably, the preparation method of the electrode material further includes pretreating the conductor. The pretreatment operations are as follows: ultrasonically wash with acetone, ethanol, and ultrapure water respectively, then reflux with 65 wt% nitric acid at 90 - 110 °C for 0.5 - 1.5 h, then wash with ultrapure water until neutral, and dry to obtain the pretreated carbon cloth.

[0064] The beneficial effects of the present invention are as follows: The organometallic complex of the present invention is essentially a bimetallic atom complex, which not only has the characteristics of simple structure, easy characterization and analysis, and simple preparation of ligands, but also has advantages such as strong controllability of the preparation method, simple process, and low energy consumption. It is particularly suitable as an electrocatalyst for the recovery and utilization of carbon dioxide. Specifically:

[0065] (1) The present invention synthesizes a bimetallic atom complex with a clear structure and coordination environment, and the metal atoms can be respectively and simultaneously anchored at two positions of pyridine nitrogen and alkyne bond. Therefore, the preparation method of the complex of the present invention can selectively regulate the types of coordinated metal atoms;

[0066] (2) The preparation method of the complex of the present invention can effectively obtain a ligand with a simple structure and effective bimetallic coordination, and can also effectively obtain a bimetallic atom complex with a structure easy to be characterized under the condition of room temperature (15 - 35 °C);

[0067] (3) When the electrode with the bimetallic atom complex of the present invention is loaded on carbon nanotubes (CNT) and used for electrocatalytic reduction of CO2, the synergistic effect of the bimetallic atoms can be fully exerted, effectively converting CO2 into CO, and moreover, showing excellent electrochemical performance. Description of the Drawings

[0068] Figure 1 It is the 1H NMR spectrum of the organic ligand L in Example 1.

[0069] Figure 2 It is the mass spectrum of the organic ligand L in Example 1.

[0070] Figure 3 It is the mass spectrum of the organometallic complex D-Pd in Example 1.

[0071] Figure 4 It is the simulated mass spectrum of the substance in the first binding form of the organometallic complex D-Pd in the mass spectrometry test.

[0072] Figure 5 It is the simulated mass spectrum of the substance in the second binding form of the organometallic complex D-Pd in mass spectrometry testing.

[0073] Figure 6 It is the simulated mass spectrum of the substance in the third binding form of the organometallic complex D-Pd in mass spectrometry testing.

[0074] Figure 7 It is the mass spectrum of the organometallic complex S-Pd in Comparative Example 1.

[0075] Figure 8 It is the simulated mass spectrum of the substance in the first binding form of the organometallic complex S-Pd in mass spectrometry testing.

[0076] Figure 9 It is the simulated mass spectrum of the substance in the second binding form of the organometallic complex S-Pd in mass spectrometry testing.

[0077] Figure 10 It is the schematic structural diagram of the catalyst on the electrode materials in Example 2 and Comparative Example 3.

[0078] Figure 11 It is the result graph of the linear sweep voltammetry test of the electrode materials in Example 2 and Comparative Example 3.

[0079] Figure 12 It is the result graph of the Faraday efficiency test of the electrode materials in Example 2 and Comparative Example 3. Detailed implementation manners

[0080] The following will clearly and completely describe the concept of the present invention and the technical effects generated in combination with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of the present invention.

[0081] Unless otherwise specified, the "single metal atom complex" in the present invention refers to a complex molecule that can ionize 1 metal atom; the "double metal atom complex" refers to a complex molecule that can ionize 2 metal atoms; however, the metals on the complex exist in the form of metal ions.

[0082] Example 1

[0083] This example provides an organic ligand L, and its structural formula is shown as follows:

[0084]

[0085] Synthesis of the organic ligand L in this example:

[0086]

[0087] First, weigh 3.3 g of 1,2-diiodobenzene, 2.3 g of 2-ethynylpyridine, 140 mg of dichloro-bis(triphenylphosphine)palladium (i.e., Pd(PPh3)2Cl2) and 76 mg of CuI into a single-necked flask. Degas under argon for 30 minutes. Add 80 mL of 0.5 M ammonia water to the reaction system, seal the reaction system, and react for 94 hours at room temperature (15 - 30 °C) under argon to obtain a reaction solution. Then, perform rotary evaporation on the reaction solution to obtain an oily residue; dissolve the obtained oily residue in dichloromethane (CH2Cl2), add water, shake, and let stand. Separate the aqueous phase and the organic phase with a separatory funnel. After that, add anhydrous NaSO4 to the organic phase, filter, and perform vacuum distillation to obtain a brown oil. Finally, use CH2Cl2 as the eluent and purify by silica gel column chromatography to obtain the organic ligand L (characteristics of the product: yellowish-brown solid).

[0088] Perform characterization tests on the yellowish-brown solid by 1H NMR and NMR mass spectrometry. The test results are as Figure 1 and Figure 2 shown.

[0089] From Figure 1 and Figure 2 it can be seen that the characterization results of the yellowish-brown solid are as follows:

[0090] 1 H NMR (400 MHz, CDCl3): δ 8.68 (d, J = 4 Hz, 2H), 7.75 (d, J = 4 Hz, 4H), 7.69 (dd, J = 3, 8 Hz, 2H), 7.40 (dd, J = 3, 8 Hz, 2H), 7.32 (q, J = 8 Hz, 2H). ESI-MS m / z: [M + H] + = 281.11. This indicates that the above reaction can successfully synthesize the organic ligand L, and the organic ligand L can be judged as 1,2-bis(2-pyridyl ethynyl)benzene.

[0091] This example also provides a preparation method of a metal-organic complex D-Pd, including the following steps:

[0092] Dissolve 50 mg of 1,2-bis(2-pyridyl ethynyl)benzene and 227 mg of bis(acetonitrile)palladium(II) chloride (chemical formula: PdCl2(MeCN)2) in 5 mL of N,N-dimethylformamide (i.e., DMF), and stir for 12 hours at room temperature (15 - 30 °C) in the dark to obtain a clear reddish-brown solution; then, add 50 mL of water to precipitate a reddish-brown mixture, and wash away the excess PdCl2(MeCN)2 with acetone to obtain the metal-organic complex D-Pd (characteristics of the product: brownish-red solid);

[0093] Among them, the molar ratio of 1,2-bis(2-pyridyl ethynyl)benzene to bis(acetonitrile)palladium(II) chloride is 1:4.9.

[0094] Add the metal-organic complex D-Pd to the DMF solvent to prepare a mass spectrometry sample, and perform mass spectrometry on it. The test results are as Figure 3 shown. Through structural analysis, during the mass spectrometry test, there are at least 3 forms of substances in the mass spectrometry sample prepared from the metal-organic complex D-Pd, and the simulated mass spectrometry diagrams of them are respectively as Figure 4 , Figure 5 , Figure 6 shown.

[0095] From Figure 3 , Figure 4 , Figure 5 and Figure 6 it can be seen that: in the actual mass spectrometry diagram of the metal-organic complex D-Pd, ESI-MS m / z: [M + 2Pd + 2Cl + H2O + CN] + = 607.86, [M + 2Pd + 2Cl + OH + CNCH3] + = 621.88, [M + 2Pd + 3Cl + CNCH3] + = 639.84, which basically corresponds to the simulated mass spectrometry diagrams of 3 forms of substances. Moreover, from the actual mass spectrometry diagram of the metal-organic complex D-Pd, there are at least 3 signal peaks of substances containing 2 Pd, which can indicate that the metal-organic complex D-Pd is a double-Pd atom complex formed by the coordination of 1 organic ligand L with 2 Pd 2+ coordination. It should be particularly noted that Figure 5 the OH in it is introduced during the test.

[0096] In addition, looking at the preparation method and conditions of the metal-organic complex D-Pd, due to the presence of chlorine with strong coordination ability to the metal in the preparation system, the structural formula of the metal-organic complex D-Pd is as follows:

[0097]

[0098] Example 2

[0099] This embodiment provides a method for preparing an electrode material, comprising the following steps:

[0100] (1) Pretreatment of carbon cloth: Take carbon cloth, ultrasonically wash it with acetone, ethanol, and ultrapure water for 10 min respectively, reflux it with concentrated nitric acid (65 wt%) at 100 °C for 1 h, then wash it with ultrapure water until neutral, and dry it to obtain the pretreated carbon cloth for standby;

[0101] (2) Weigh 2.5 mg of the metal-organic complex D-Pd in Example 1, dissolve it in 2 mL of N,N-dimethylformamide (i.e., DMF), add 5 mg of carbon nanotubes (i.e., CNT), and ultrasonicate for 8 hours; then dropwise add 50 μL of 5 wt% Nafion solution thereto and continue ultrasonication for 30 minutes to obtain a dispersion; thereafter, take 400 μL of the dispersion and drop it on the 2 pretreated carbon cloth of 1 cm to obtain the electrode material;

[0102] Among them, the electrode material in step (2) is a catalyst of the metal-organic complex D-Pd supported on carbon nanotubes; the schematic diagram of the structure of this catalyst is as shown in Figure 10 (b) in.

[0103] Comparative Example 1

[0104] The structural formula and preparation method of the organic ligand L used in this comparative example are the same as those in Example 1.

[0105] This comparative example provides a method for preparing an organometallic complex S-Pd, comprising the following steps:

[0106] (1) Dissolve 20 mg of 1,2-bis(2-pyridyl ethynyl)benzene in 0.78 mL of CH2Cl2 to prepare a dichloromethane solution containing the organic ligand L;

[0107] Dissolve 22.9 mg of bis(acetonitrile)palladium dichloride (chemical formula: PdCl2(MeCN)2) in 2.69 mL of acetonitrile (chemical formula: MeCN) to prepare an acetonitrile solution of bis(acetonitrile)palladium dichloride;

[0108] (2) Slowly drop the acetonitrile solution of bis(acetonitrile)palladium dichloride in step (1) onto the upper layer of the dichloromethane solution containing the organic ligand L, seal the mixture, let it stand and react in the dark for one day, then filter to obtain a precipitate, wash it with methanol, and dry it at room temperature (25 - 30 °C) to obtain the organometallic complex S-Pd (characteristics of the product: yellow solid powder);

[0109] Among them, the molar ratio of 1,2-bis(2-pyridyl ethynyl)benzene to bis(acetonitrile)palladium(II) chloride is 1:1.2.

[0110] The metal-organic complex S-Pd was added to DMF solvent to prepare a mass spectrometry sample, and mass spectrometry was performed on it. The test results are as Figure 7 shown. Through structural analysis, during the mass spectrometry test, there are at least two forms of substances in the mass spectrometry sample prepared from the metal-organic complex S-Pd, and the mass spectrometry diagrams simulated by them are respectively as Figure 8 , Figure 9 shown.

[0111] From Figure 7 , Figure 8 and Figure 9 it can be seen that in the actual mass spectrometry diagram of the metal-organic complex S-Pd, ESI-MS m / z: [M+Pd+Cl+CNCH3] + = 464, [M+Pd+Cl] + = 422.97, which basically corresponds to the simulated mass spectrometry diagrams of two forms of substances. Moreover, from the fact that there are at least two substances containing one Pd in the actual mass spectrometry diagram of the metal-organic complex S-Pd, it can be shown that the metal-organic complex S-Pd is a single Pd atom complex formed by the coordination of one organic ligand L and one Pd 2+ coordination.

[0112] In addition, looking at the preparation method and conditions of the metal-organic complex S-Pd, due to the presence of chlorine with strong coordination ability to the metal in the preparation system, the structural formula of the metal-organic complex S-Pd is as follows:

[0113]

[0114] Comparative Example 2

[0115] The structural formula and preparation method of the organic ligand L used in this comparative example are the same as those in Example 1.

[0116] This comparative example provides a preparation method of an organometallic complex, which is different from Example 1 only in that the molar ratio of 1,2-bis(2-pyridyl ethynyl)benzene to bis(acetonitrile)palladium dichloride is replaced by 1:2.9, and includes the following steps:

[0117] Dissolve 50 mg of 1,2-bis(2-pyridyl ethynyl)benzene and 136 mg of bis(acetonitrile)palladium(II) (chemical formula: PdCl2(MeCN)2) in 5 mL of N,N-dimethylformamide (i.e., DMF), and stir at room temperature (15 - 30 °C) in the dark for 12 hours to obtain a clear red-brown solution; then, add 50 mL of water to precipitate a brown mixture, and wash away the excess PdCl2(MeCN)2 with acetone to obtain the metal-organic complex (characteristics of the product: yellow solid powder);

[0118] Among them, the molar ratio of 1,2-bis(2-pyridyl ethynyl) benzene to bis(acetonitrile)palladium(II) chloride is 1:2.9.

[0119] The organometallic complex in this comparative example was added to a DMF solvent to prepare a mass spectrometry sample, and its mass spectrometry was performed. The test results were basically similar to those of Comparative Example 1, indicating that this organometallic complex was a single Pd atom complex formed by the coordination of 1 organic ligand L and 1 Pd 2+ coordination.

[0120] Comparative Example 3

[0121] This comparative example provides a method for preparing an electrode material, including the following steps:

[0122] (1) Pretreatment of carbon cloth: Take carbon cloth, ultrasonically wash it with acetone, ethanol, and ultrapure water for 10 min respectively. After refluxing with concentrated nitric acid (65 wt%) at 100 °C for 1 h, wash it with ultrapure water until neutral, and dry it to obtain the pretreated carbon cloth;

[0123] (2) Weigh 2.5 mg of the organometallic complex S-Pd in Comparative Example 1, dissolve it in 2 mL of N,N-dimethylformamide (i.e., DMF), add 5 mg of carbon nanotubes (i.e., CNT), and ultrasonicate for 8 hours; then dropwise add 50 μL of 5 wt% Nafion solution to it and continue ultrasonication for 30 minutes to obtain a dispersion; then take 400 μL of the dispersion and drop it on 1 cm 2 of the pretreated carbon cloth to obtain the electrode material;

[0124] Among them, the electrode material in step (2) contains a catalyst of the organometallic complex S-Pd loaded on carbon nanotubes; a schematic diagram of the structure of this catalyst is as Figure 10 shown in (a) of.

[0125] Performance test

[0126] Test samples: the electrode material in Example 2, the electrode material in Comparative Example 3

[0127] Performance test method:

[0128] (1) Test of voltammetric curve: In an H-type electrolytic cell, use the test sample as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum sheet as the counter electrode, and use Ar-saturated KHCO3 solution and CO2-saturated KHCO3 solution as the electrolytes respectively; use a CHI 660 model electrochemical workstation to set the test under the conditions of a potential of 0 to -1.30 V vs. RHE and a scanning speed of 0.01 V / s; the linear sweep voltammetry test results of the electrode materials in Example 2 and Comparative Example 2 are shown in Figure 11 as shown.

[0129] It can be seen from Figure 11 that: The linear sweep voltammogram shows that the current density of the electrode materials in Example 2 and Comparative Example 3 under saturated CO2 conditions is significantly higher than that under Ar conditions, indicating that the catalysts on both electrodes are active for CO2 reduction. Moreover, compared with the S-Pd-containing electrode material in Comparative Example 3, the D-Pd-containing electrode material in Example 2 has significantly lower overpotential and significantly higher current density, indicating that the D-Pd-containing electrode material has higher catalytic activity in carbon dioxide reduction.

[0130] (2) Test of Faraday efficiency: In an H-type electrolytic cell, the test sample is used as the working electrode, the Ag / AgCl electrode is used as the reference electrode, the platinum sheet is used as the counter electrode, and the KHCO3 solution saturated with CO2 is used as the electrolyte; using a CHI 660 model electrochemical workstation, the performance of electrocatalytic reduction of carbon dioxide is tested at a potential of -0.6 to -1.2 V vs. RHE, and the measured results are as Figure 12 shown.

[0131] It can be seen from Figure 12 that: The comparison chart of Faraday efficiency shows that: Through design of the feed and calculation, it can be known that under the condition of the same number of metal active sites, the potential window and Faraday efficiency of the D-Pd-containing electrode material in Example 2 are significantly better than those of the S-Pd-containing catalyst electrode material in Comparative Example 3. Moreover, the potential window and Faraday efficiency of the D-Pd-containing electrode material in Example 2. At a potential of -0.7 V vs. RHE, the Faraday efficiency of CO is up to 94.4%, and the Faraday efficiency of CO measured under the condition of a relatively wide potential window (-0.6 to -1.1 V vs. RHE) is above 80%.

[0132] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. An organometallic complex, characterized in that, The structure is as follows: 。 2. The preparation method of the organometallic complex according to claim 1, characterized in that, It includes the following steps: 1) Dissolve an organic ligand and a soluble metal salt in solvent A to obtain solution A; 2) Add antisolvent B to solution A, and wash the precipitate with cleaning agent C to obtain an organometallic complex; Among them, the structure of the organic ligand in step 1) is as follows: , the soluble metal salt in step 1) is bis(acetonitrile)palladium(II) chloride, and the molar ratio of the organic ligand to the soluble metal salt in step 1) is 1:(3.5 - 10).

3. The preparation method of the organometallic complex according to claim 2, characterized in that: In step 1), the solvent A is one or more of N,N-dimethylformamide and dimethyl sulfoxide; in step 2), the antisolvent B is one or more of water, chloroform, isopropanol, and dichloromethane; in step 2), the cleaning agent C is one or more of acetone, toluene, and ethyl acetate.

4. Application of a complex in an electrocatalytic reduction reaction, characterized in that: The complex is the organometallic complex described in claim 1.

5. The application according to claim 4, characterized in that: The reduction reaction is a reaction for carbon dioxide reduction; the product of the reduction reaction is carbon monoxide.

6. A catalyst, characterized in that: The catalyst includes the organometallic complex described in claim 1 and a carbon material, and the organometallic complex is supported on the carbon material.

7. An electrode material, characterized in that: The electrode material includes the catalyst described in claim 6.

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