Copper metal complex for electrocatalytic water oxidation reaction and preparation method thereof
By preparing a copper metal complex catalyst, the problem of slow oxygen evolution rate at the anode in water electrolysis for hydrogen production was solved, realizing low-temperature and high-efficiency electrocatalytic water oxidation. The catalyst exhibits excellent catalytic performance at a current density of 0.2 mA cm⁻², with low overpotential, meeting the requirements of green chemical production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2026-03-20
- Publication Date
- 2026-05-12
AI Technical Summary
In existing water electrolysis hydrogen production technologies, the oxygen evolution reaction at the anode has high thermodynamic energy, resulting in a slow reaction rate. Therefore, it is necessary to develop efficient and stable catalysts to improve the efficiency of water electrolysis.
A copper metal complex catalyst was prepared by reacting diethylenetriamine as a ligand with copper perchlorate hexahydrate for electrocatalytic water oxidation. The electrolyte was 0.1 M potassium nitrate aqueous solution, the electrolysis potential was 1.56 V vs. NHE, the catalyst concentration was not determined, and the reaction was carried out at neutral pH.
A simple and efficient electrocatalytic water oxidation process was achieved under low-temperature conditions. The catalyst exhibited good catalytic performance, with a water oxidation initiation potential of 1.048 V vs. NHE at a current density of 0.2 mA cm⁻², a voltage of 1.586 V vs. NHE at 1 mA cm⁻², and an overpotential of 359.7 mV, avoiding the pollution problems of traditional methods.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of new materials technology, and specifically discloses a simple, efficient, green metal-organic complex catalyst based on diethylenetriamine organic ligands at a lower temperature, its preparation method, and its application in electrocatalytic water oxidation. Background Technology
[0002] Environmental pollution and the energy crisis are two particularly serious problems today, making the search for clean energy a crucial task for economic and social development. Among the many known green and clean energy sources, hydrogen is an excellent choice, primarily because it has high energy density, is easy to store, and produces only water upon combustion. These characteristics make hydrogen a preferred alternative to traditional energy sources. Currently, there are many methods for obtaining hydrogen, with water electrolysis being a relatively mature and promising technology. However, the high thermodynamic energy required for the oxygen evolution reaction at the anode results in a slow reaction rate, which is the biggest problem in water electrolysis. Therefore, developing catalysts with good catalytic effect and stability is crucial and key to improving the efficiency of water electrolysis. Summary of the Invention
[0003] To address the problems existing in the prior art, this invention provides a copper metal complex, its preparation method, and its application in electrocatalytic water oxidation.
[0004] The technical solution adopted in this invention is: a copper metal complex for electrocatalytic water oxidation reaction, wherein the structural formula of the complex is:
[0005] .
[0006] A method for preparing copper metal complexes for electrocatalytic water oxidation includes the following steps:
[0007] S1. Copper perchlorate hexahydrate was added to anhydrous methanol containing diethylenetriamine ligand, stirred and filtered at room temperature to obtain a blue solid;
[0008] The molar ratio of copper perchlorate hexahydrate to diethylenetriamine ligand is 1:2;
[0009] S2 was then dissolved in acetonitrile to obtain a blue solution. Diethyl ether was then added to precipitate a solid, which was then dried in an oven to obtain a copper metal complex.
[0010] Furthermore, the copper metal complex is used in the electrocatalytic water oxidation reaction.
[0011] Furthermore, the electrolyte in the electrocatalytic water oxidation reaction is a 0.1 M potassium nitrate aqueous solution.
[0012] Furthermore, the electrolytic potential applied during the reaction is 1.56 V vs. NHE.
[0013] Furthermore, the concentration of the catalyst added to the homogeneous system is...
[0014] The raw materials selected in this invention are diethylenetriamine as a ligand and copper perchlorate hexahydrate. The resulting copper metal complex catalyst exhibits good catalytic performance in the electrocatalytic water oxidation reaction, and can be used at a current density of 0.2 mA cm⁻¹. -2 Electrolysis at the specified voltage for 2 hours resulted in a water oxidation initiation potential of 1.048 V vs. NHE (vs. NHE relative to the reversible hydrogen electrode), reaching 1 mA cm⁻¹. -2 The voltage is 1.586 V vs. NHE, and the overpotential is 359.7 mV. Furthermore, the method provided by this invention is simple to operate, highly safe, has mild reaction conditions, and is environmentally friendly. It effectively avoids the drawbacks and problems of traditional chemical oxidation processes, such as the use of strong oxidants, the generation of difficult-to-treat waste, and the emission of large amounts of greenhouse gases, which are inconsistent with the concept of green chemical production.
[0015] The copper metal complex of the present invention has the molecular formula [Cu(DETA)2], wherein Cu is a divalent ion and DETA is a diethylenetriamine organic ligand, and its chemical structural formula is as follows:
[0016]
[0017] The method for preparing the copper metal complex of the present invention comprises the following steps:
[0018] Copper perchlorate hexahydrate (0.371 g, 1.0 mm) was slowly added to 3 mL of anhydrous methanol containing 0.206 g (2.0 mmol) of DETA ligand. The mixture was stirred at room temperature for 20 h, filtered, and a blue solid was obtained. The blue solid was then dissolved in 5 mL of acetonitrile to form a blue solution. Subsequently, 20 mL of diethyl ether solution was added and filtered. The obtained solid was dried in an oven for 10 h, yielding 0.430 g of the blue metal complex Cu(DETA)₂ with a yield of 90%.
[0019] The catalytic synthesis was carried out under the following conditions: pH neutral, room temperature, and under stirring, sonication, or shaking.
[0020] The copper metal complex catalyst prepared in this invention exhibits excellent catalytic performance in the electrocatalytic oxidation of water, and can operate at a current density of 0.2 mA cm⁻¹. -2Electrolysis at a voltage of 1 mA cm⁻¹ for 2 hours resulted in a water oxidation initiation potential of 1.048 V vs. NHE (vs. NHE relative to the reversible hydrogen electrode), reaching 1 mA cm⁻¹. -2 The voltage is 1.586 V vs. NHE, and the overpotential is 359.7 mV.
[0021] This invention provides a rapid, simple, green, and efficient method for synthesizing copper metal complexes. Compared with traditional methods, this invention has the following outstanding advantages: the solvent used in the reaction is readily available, inexpensive, and environmentally friendly; the reaction conditions are simple, the reaction can proceed rapidly, and it saves energy and time.
[0022] This catalyst exhibits high yield, low ligand usage, and cost savings. It demonstrates excellent catalytic performance in the electrocatalytic oxidation of water, showing good catalytic activity at a current density of 0.2 mAcm⁻¹ in electrochemical tests. -2 Electrolysis at the specified voltage for 2 hours resulted in a water oxidation initiation potential of 1.048 V vs. NHE (vs. NHE relative to the reversible hydrogen electrode), reaching 1 mA cm⁻¹. -2 The voltage is 1.586 V vs. NHE, and the overpotential is 359.7 mV.
[0023] In summary, this invention synthesizes a novel catalyst, Cu(DETA)₂, at room temperature using an organic ligand of diethylenetriamine (DETA) and copper perchlorate hexahydrate. This method is simple, efficient, and environmentally friendly, providing effective guidance for expanding the data collection of copper metal complex materials and holding significant value for research on homogeneous catalysts in the electrocatalytic oxidation of water. Attached Figure Description
[0024] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:
[0025] Figure 1 This is a schematic diagram of the structure of the complex prepared in Example 1 of the present invention;
[0026] Figure 2 Infrared spectrum of the copper metal complex in this invention;
[0027] Figure 3 The ultraviolet-visible spectrum of the copper metal complex in this invention.
[0028] Figure 4 Electrochemical CV diagram of the copper metal complex in this invention.
[0029] Figure 5 Faraday efficiency diagram of the copper metal complex in this invention.
[0030] Figure 6 Analysis diagram of the polishing experiment of the copper metal complex in this invention. Detailed Implementation
[0031] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.
[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. In this invention, unless otherwise specified, the reagents and materials are commercially available; and the experimental methods, unless otherwise specified, are conventional methods.
[0033] In this invention, unless otherwise specified, M represents mol / L and mM represents mmol / L.
[0034] Example 1: This example relates to the preparation of copper metal complexes:
[0035] The synthesis method of the molecular catalyst Cu(DETA)2 involved slowly adding copper perchlorate hexahydrate (0.371 g, 1.0 mm) to 3 mL of anhydrous methanol containing 0.206 g (2.0 mmol) of DETA ligand. The mixture was stirred at room temperature for 20 h, filtered, and a blue solid was obtained. The blue solid was then dissolved in 5 mL of acetonitrile to form a blue solution. Subsequently, 20 mL of diethyl ether solution was added and filtered. The obtained solid was dried in an oven for 10 h, yielding 0.430 g of the blue metal complex Cu(DETA)2 with a yield of 90%.
[0036] Q-Tof Micro (m / z): [M+H]⁺ Theoretical calculated value: m / z 269.15; Measured value: m / z 269.1. The infrared-visible and ultraviolet-visible spectra of this complex are shown in Figures 2-3.
[0037] The ligand DETA and the catalyst Cu(DETA)₂ were characterized using Fourier transform infrared (FT-IR). As shown in Figure 2, the ligand at 3318 cm⁻¹... -1 The peak at 1066 cm⁻¹ is due to the stretching vibration of the NH bond; the catalyst at 1066 cm⁻¹... -1 The spike at 2929 cm⁻¹ is caused by N-Cu bond vibration, and the ligand can be observed at 2929 cm⁻¹. -1The peak of CH bond vibration stretching at the point is smaller. Compared with the catalyst, the peak value at this point is smaller. This is due to the formation of coordinate bonds between the ligand and copper ions. This indicates that N-Cu coordinate bonds are formed in the catalyst, which also proves the correctness of the catalyst synthesis.
[0038] The UV-Vis absorption spectra of the ligand and catalyst were studied at room temperature. The tests were conducted in a 0.1 mM neutral potassium nitrate aqueous solution, and the results are shown in Figure 3. The ligand DETA at λ... max There is a strong absorption peak at λ = 242 nm, while at λ... max =620 nm has a weak absorption peak, which is the same position as the UV-Vis absorption spectrum reported in the literature. This peak is attributed to the charge transfer (MLCT) absorption peak of copper metal to ligand.
[0039] The crystal structure was obtained by cultivating single crystals at room temperature (293 K) using a solvent diffusion method. The specific steps are as follows: A 10 mM acetonitrile solution of the molecular catalyst Cu(DETA)₂ was prepared at room temperature. Approximately 2–3 mL of this solution was placed in a 10 mL test tube. 20 mL of anhydrous diethyl ether was added to a clean 100 mL Schlenk flask. The test tube containing the catalyst was then placed inside the Schlenk flask, and the flask was sealed with a rubber stopper. The mixture was left to stand for several days. As the diethyl ether slowly evaporated into the test tube, the dissolved catalyst gradually grew into crystals. The crystals were then collected for testing.
[0040] The structure of the collected catalysts was analyzed by X-ray single-crystal diffraction using a Bruker SMART APEX II CCD single-crystal diffractometer.
[0041] Table 1 Crystal parameters of Cu(DETA)2
[0042]
[0043] Example 2: This example involves the electrocatalytic water oxidation reaction of a complex:
[0044] The electrochemical reaction apparatus includes a Shanghai Chenhua 730E electrochemical workstation, a 10 mL single-cell electrolytic cell, a stirring device, a working electrode, a counter electrode, and a reference electrode. The working electrode is a glassy carbon electrode, the counter electrode is a platinum wire electrode, and the reference electrode is a silver-silver chloride electrode. The distance between the working electrode and the counter electrode is approximately 1.5 cm.
[0045] The treatment method for the working electrode (glassy carbon electrode) is as follows: Clean with ethanol, acetone, and deionized water sequentially, then air-dry for later use. The treatment method for the counter electrode (platinum wire) is as follows: Clean with 3M hydrochloric acid, ethanol, and deionized water sequentially using ultrasonic cleaning for 10 minutes, then air-dry for later use.
[0046] The following example follows these steps: (1) Prepare the electrolyte and the amount of catalyst as required. (2) Before testing, bubble the electrolytic cell with nitrogen for 30 minutes to remove dissolved oxygen from the water. (3) Set the optimal reaction temperature, voltage during electrolysis, and scan rate. (4) During electrolysis, use a NeoFox optical oxygen sensor to detect oxygen generation in real time and perform quantitative analysis.
[0047] The electrochemical behavior of the catalyst was studied using CV and DPV in a 0.1 mM neutral potassium nitrate aqueous solution, as shown in Figure 4. 1 / 2 There is an oxidation peak at 1.125 V vs. NHE, which is attributed to Cu. Ⅲ / Cu Ⅱ The redox process in E p There is an oxidation peak at 1.28 V vs. NHE. As mentioned above, this peak belongs to the oxidation of the ligand itself and does not participate in the water oxidation process. At E... p The peak at 1.55 V vs. NHE is attributed to the catalytic water oxidation peak. As can be seen from the figure, the catalytic current is much higher than that of the blank potassium nitrate aqueous solution without a catalyst.
[0048] A constant voltage electrolysis (CPE) experiment was conducted in a 0.1 M neutral KNO3 aqueous solution containing 0.55 mM catalyst at a bias voltage of 1.56 V vs. NHE. The test results are shown in Figure 5. During the two-hour electrolysis process, the electrolysis current density containing the catalyst was much higher than that of the blank solution, so the amount of charge accumulated in the blank solution was negligible. The experimental results show that the amount of charge accumulated increases linearly with the increase of electrolysis time. After two hours of electrolysis, a charge of 1.385 C was accumulated (Figure 5). During the electrolysis process, the generation of oxygen was detected in real time using a NeoFox optical oxygen sensor. After two hours of electrolysis, approximately 6.8 μmol of oxygen was detected. The calculated Faraday efficiency of this catalyst for water electrolysis is approximately 78.01%.
[0049] The glassy carbon electrode was polished, and 20 CV scans were performed on the electrolyte containing the catalyst. After that, the glassy carbon electrode was not polished, but only rinsed with a small amount of deionized water to remove the old electrolyte. Then, the unpolished glassy carbon electrode was placed in a new electrolyte without the catalyst for CV testing. The experimental results are shown in Figure 6. It was found that there was no effect of electrocatalytic water oxidation. Therefore, it was confirmed that no new oxides or hydroxides were generated on the electrode surface, and the catalytic effect was still achieved by the molecular catalyst.
[0050] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.
Claims
1. A copper metal complex for electrocatalytic water oxidation reaction, characterized in that: The structural formula of the complex is: 。 2. The method for preparing the copper metal complex for electrocatalytic water oxidation reaction according to claim 1, characterized in that, Includes the following steps: S1. Copper perchlorate hexahydrate was added to anhydrous methanol containing diethylenetriamine ligand, stirred and filtered at room temperature to obtain a blue solid; The molar ratio of copper perchlorate hexahydrate to diethylenetriamine ligand is 1:2; S2 was then dissolved in acetonitrile to obtain a blue solution. Diethyl ether was then added to precipitate a solid, which was then dried in an oven to obtain a copper metal complex.
3. The application of the copper metal complex of claim 1 for electrocatalytic water oxidation reaction, characterized in that: The copper metal complex is used in the electrocatalytic water oxidation reaction.
4. The application according to claim 3, characterized in that, The electrolyte used in the electrocatalytic water oxidation reaction is a 0.1 M potassium nitrate aqueous solution.
5. The application according to claim 3, characterized in that, The electrolytic potential applied during the reaction is 1.56 V vs. NHE.
6. The application according to claim 3, characterized in that, The concentration of the catalyst added to the homogeneous system is 0.4-0.8 mmol / L.