Spinel type catalyst for preparing chlorine through electro-catalysis and preparation method of spinel type catalyst

Abstract

The invention discloses a spinel type catalyst for preparing chlorine through electro-catalysis and a preparation method of the spinel type catalyst, and relates to the technical field of electro-catalysis materials. The catalyst is a nickel-doped cobalt spinel oxide, the chemical general formula of the catalyst is NixCo3-xO4, the value range of x is 0.4-0.6, the crystal structure of the catalyst belongs to a cubic system spinel structure, and nickel ions selectively occupy octahedral sites in spinel crystal lattices and partially replace original Co < 3 + > ions. The spinel type non-noble metal catalyst with high chlorine evolution activity, high selectivity and good stability is constructed by accurately controlling the nickel doping concentration and optimizing hydrothermal and annealing process parameters.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrocatalytic materials, and particularly relates to a spinel catalyst for electrocatalytic preparation of chlorine and a preparation method thereof. BACKGROUND

[0002] As a basic chemical raw material, the annual output of chlorine in China has broken through 38 million tons, accounting for 42.7% of the global share. It is widely used in the synthesis of polyvinyl chloride, the manufacture of disinfectants and the production of fine chemicals in many key fields. It can be seen that its preparation process is directly related to the safety and sustainable development of the national basic industry. The current industry generally uses the chlor-alkali electrolysis method, that is, electrolyzing saturated sodium chloride solution in an ion membrane electrolytic cell, chlorine is generated at the anode and caustic soda is generated at the cathode. This process is mature and efficient, but its core depends on the performance of the dimensionally stable anode. The dimensionally stable anode is usually composed of a solid solution active layer formed by titanium substrate loaded with noble metal oxides (such as ruthenium dioxide or iridium dioxide) and titanium dioxide. The noble metal component accounts for about 30%, which can effectively catalyze the chlorine evolution reaction and inhibit the oxygen evolution side reaction, ensuring high current efficiency and long-term operation stability. However, its high cost and high dependence on scarce strategic metal resources have become a bottleneck restricting the green and low-carbon transformation of the chlor-alkali industry. Under this background, the development of non-noble metal anode materials with high catalytic activity, excellent selectivity and good stability has become an urgent need for the upgrading of the industry.

[0003] Spinel-type Co3O4 is considered a highly promising alternative candidate due to its unique crystal structure and electrochemical properties. This material possesses the general formula AB2O4, where divalent cobalt occupies tetrahedral interstitials and trivalent cobalt occupies octahedral sites. This tunable cation distribution endows it with abundant redox activity and good electronic conductivity. Furthermore, its structure can be finely modified through morphology control, crystal face exposure, defect introduction, or heteroelement doping, thereby optimizing the surface electronic state density and adsorption energy, theoretically providing a basis for improving the kinetics of chlorine evolution reactions. However, existing research largely focuses on combining Co3O4 with carbon-based supports (such as carbon nanotubes, graphene, or MXene) to enhance conductivity or dispersion, while research on directly controlling its intrinsic electronic structure through heteroatom doping is relatively scarce. The patent application CN115710719A discloses a "non-noble metal chlorine evolution anode" that uses electrodeposition combined with low-temperature annealing to construct multilayer Co3O4 nanosheets with a single-layer thickness of only 15-25 nm and a total thickness of 30-50 nm on a titanium mesh. While this method avoids the use of precious metals, its preparation route has fundamental limitations: on the one hand, the electrodeposition process struggles to achieve atomically uniform doping, leading to uneven distribution of active sites; on the other hand, although low-temperature annealing (300℃) can form a spinel phase, it cannot fully activate the electron migration channels in the crystal lattice, nor can it introduce effective lattice strain or vacancy defects to optimize the adsorption / desorption behavior of chlorine intermediates. More importantly, this structure lacks an effective mechanism to inhibit the competitive oxygen evolution reaction in the chlorine evolution reaction, resulting in a significant decrease in selectivity under high current density conditions, and in actual operation, it is prone to accelerated catalyst deactivation due to the aggravation of side reactions. Although CN114433091A synthesized CuCo2O4 spinel, its application scenario is dichloromethane reduction dechlorination, not chlorine evolution anode. Its material design logic differs fundamentally from the needs of this field, and its application in chlor-alkali electrolysis results in less than ideal activity and chlorine selectivity.

[0004] Ultimately, the aforementioned existing technical solutions fail to resolve a deep-seated technical contradiction at the material design level: how to simultaneously enhance the intrinsic activity of catalytic active sites and the selective control over target reaction pathways without sacrificing structural stability. While Co3O4 itself possesses certain chlorine evolution activity, the cobalt ions at its octahedral sites are less effective against oxygen-containing materials (such as OH-). - O 2-Excessive adsorption of oxygen intermediates can easily induce oxygen evolution side reactions. Simply increasing the specific surface area or conductive network can only improve the apparent current density and cannot weaken the adsorption strength of oxygen intermediates at the electronic structure level. Therefore, relying solely on physical recombination or surface morphology control is insufficient to overcome the inherent ceiling of catalytic selectivity. To overcome this limitation, precise hetero-cation doping may be needed to control the valence state and d-band center of cobalt ions in the spinel lattice, thereby thermodynamically suppressing oxygen evolution and kinetically promoting chloride ion oxidation. However, existing electrodeposition-annealing routes cannot achieve this directional optimization of electronic structure due to narrow process windows and poor doping controllability. Therefore, how to construct a spinel-type catalyst with high intrinsic activity and excellent chlorine selectivity that can be precisely controlled through atomic-level doping, and develop a scalable and highly reproducible preparation method, has become a key technical challenge in promoting the industrial application of non-noble metal chloride evolution anodes. Summary of the Invention

[0005] This invention provides a spinel-type catalyst for the electrocatalytic preparation of chlorine. The catalyst is nickel-doped spinel-type cobalt tetroxide (Ni-Co3O4), in which some cobalt ions are replaced by nickel ions in its crystal structure, forming an AB2O4-type spinel phase with an optimized electronic structure. The A sites are occupied by divalent cobalt, and the B sites are occupied by divalent nickel and trivalent cobalt. The catalyst is prepared by hydrothermal synthesis combined with high-temperature annealing. The resulting material has a uniform elemental distribution, a controllable cation ratio, and a complete spinel lattice structure, making it suitable for highly efficient and selective catalytic chlorine evolution reaction in sodium chloride electrolyte. This solves the technical problem of the difficulty in simultaneously achieving high activity and chlorine selectivity in existing "non-precious metal chlorine evolution anodes".

[0006] The technical solution adopted in this invention is as follows: In a first aspect, the present invention provides a spinel-type catalyst for the electrocatalytic preparation of chlorine, wherein the catalyst is a nickel-doped cobalt spinel oxide with the general chemical formula Ni. x Co 3-x O4, where x ranges from 0.4 to 0.6, has a cubic spinel crystal structure. Nickel ions selectively occupy octahedral sites in the spinel lattice, partially replacing the original Co. 3+ ion.

[0007] Preferably, the value of x is 0.5.

[0008] In a second aspect, the present invention provides a method for preparing the spinel-type catalyst for electrocatalytic preparation of chlorine as described in the first aspect, comprising the following steps: (1) Using a mixed solvent of ethanol and deionized water as a solvent, nickel nitrate and cobalt nitrate are dissolved according to the general formula ratio described in claim 1 or 2. After complete dissolution, ammonia water is rapidly added to the solution under vigorous stirring. The solution quickly becomes turbid and is stirred for 5 to 20 minutes to form a uniform slurry. (2) Transfer the slurry obtained in step (1) into a high-pressure reactor, seal it, and place it in an oven at 140~160℃ for hydrothermal reaction for 3~5 hours; (3) After the reactor cools naturally to room temperature, the product in the reactor is centrifuged, washed, dried and ground to obtain black precursor powder; (4) The black precursor powder was placed in a tube furnace and calcined at 300~500℃ for 2 hours in air atmosphere at a heating rate of 5℃ / min to obtain nickel-doped cobalt spinel oxide Ni. x Co 3-x O4.

[0009] Furthermore, in step (1), the molar ratio of nickel nitrate to cobalt nitrate is 1:5; Furthermore, in step (1), the volume ratio of ethanol to deionized water is 10~20∶1; Further, in step (1), the concentration of ammonia water is 25 wt%, and the amount used is 10-20% of the total volume of the reaction system.

[0010] Thirdly, the present invention discloses the application of the spinel-type catalyst described in the first aspect for the electrocatalytic preparation of chlorine as an electrocatalyst in the electrocatalytic preparation of chlorine.

[0011] Compared with the prior art, the present invention has the following advantages and beneficial effects: The Ni constructed in this invention x Co 3-x The O4 spinel catalyst system, through an atomic-scale cation doping strategy, achieves targeted control of the electronic structure and surface reaction pathways of non-noble metal oxides, fundamentally solving the technical bottlenecks of insufficient activity and low selectivity of traditional Co3O4 materials in the chlorine evolution reaction. This technical solution does not rely on a carbon-based conductive support, avoiding the structural collapse problem caused by carbon corrosion at high potentials, and also eliminates the need for composite noble metal components, completely freeing it from dependence on strategically scarce resources such as ruthenium and iridium. Therefore, this invention not only provides a high-performance, low-cost new anode material for chlor-alkali electrolysis, but also provides a universal material design paradigm for other electrocatalytic processes involving competitive anodic reactions (such as chlorine / oxygen evolution coupling systems). Attached Figure Description

[0012] Figure 1 Ni prepared in Example 1 0.5 Co 2.5X-ray diffraction patterns of O4 spinel catalyst and pure Co3O4 spinel; Figure 2 Ni prepared in Example 1 0.5 Co 2.5 Raman spectroscopy of O4 spinel catalyst and pure Co3O4 spinel; Figure 3 Ni prepared in Example 1 0.5 Co 2.5 Scanning electron microscope image of O4 spinel catalyst; Figure 4 Ni prepared in Example 1 0.5 Co 2.5 Elemental distribution diagram of O4 spinel catalyst; Figure 5 Polarization curves of spinel catalysts with different Ni contents. Detailed Implementation

[0013] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0014] Throughout this specification, unless otherwise specified, the terminology used herein should be understood to have the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0015] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0016] All electrochemical tests in this invention were performed using a CHI760e electrochemical workstation. The tests were conducted in a three-electrode system, using a catalyst-loaded rotating ring-disc electrode as the working electrode, silver / silver chloride as the reference electrode, and a platinum sheet as the counter electrode. The electrolyte was a 2M NaCl solution with pH=2. To prepare the working electrode, 2 mg of the above catalyst was accurately weighed into a 1.5 mL volumetric flask, and 300 μL of ethanol, 200 μL of water, and 20 μL of 5 wt% Nafion solution were added. The mixture was ultrasonically dispersed for 1 hour to obtain a homogeneous ink. 12 μL of this ink was uniformly coated onto the surface of a pre-polished and cleaned 0.55 cm diameter rotating ring-disc electrode. After drying at room temperature, the catalyst loading on the electrode was approximately 0.2 mg / cm². -2Cyclic voltammetry (CV) was performed to activate the sample surface and ensure stability for subsequent tests. The voltage range of CV was 1.2–1.7 V vs. RHE, and the scan rate was 0.1 V / s. -1 The cycle number is 50 times, typically until stable. A linear voltammetric scan (LSV) is performed to measure the catalyst activity. The voltage range for the LSV is 1.2–1.7 V vs. RHE, and the scan rate is 0.005 V / s. -1 95% resistance compensation was applied to eliminate the voltage drop caused by solution resistance, ensuring that the applied voltage was entirely used to drive the electrode reaction. Cl2 selectivity was tested using a rotating ring-disk electrode (RRDE). When evaluating chlorine selectivity using the RRDE, a potential sufficient to generate a current density greater than 10 mA cm⁻² was applied to the disk electrode for 600 seconds for chronoamperometric testing, while the ring electrode potential was fixed at 0.95 V and the rotation speed was set to 1600 rpm to accurately measure and record the current on the ring electrode. The chlorine selectivity was calculated as follows: Formula 1; where I ring I represents the current (A) collected from the ring electrode at a fixed potential of 0.95V. disk This represents the current (A) collected from the disk electrode, and N is the calibration collection factor (≈0.37).

[0017] The technical solution of the present invention will be described in detail below with reference to specific embodiments, so that those skilled in the art can fully understand and implement the present invention.

[0018] Example 1 Ni 0.5 Co 2.5 Preparation of O4 catalyst: 23 mL of ethanol and 2 mL of deionized water were added to a 50 mL beaker as solvents. Then, 97 mg of nickel nitrate hexahydrate and 485 mg of cobalt nitrate hexahydrate were weighed and added to the beaker. The mixture was stirred on a magnetic stirrer until completely dissolved. Under vigorous stirring, 2.5 mL of 25% ammonia solution was rapidly added to the solution, which quickly became turbid. Stirring was continued for 10 minutes to form a homogeneous slurry. This slurry was transferred to the lining of a 50 mL high-pressure reactor, sealed, and reacted in an oven at 150 °C for 3 hours. After the reactor cooled naturally to room temperature, the product was centrifuged and washed five times with a 70% ethanol aqueous solution. The resulting solid was dried in a vacuum drying oven at 60 °C for 12 hours and ground to obtain a black precursor powder. This powder was placed in a tube furnace and calcined at 400 °C for 2 hours under air atmosphere at a rate of 5 °C / min to obtain Ni. 0.5 Co 2.5 O4 spinel catalyst.

[0019] like Figure 1As shown, this is the Ni prepared in this embodiment. 0.5 Co 2.5 X-ray diffraction patterns of O4 spinel catalyst and pure Co3O4 spinel show that the Ni prepared in this example... 0.5 Co 2.5 O4 spinel catalyst has the same spinel crystal form as pure Co3O4 spinel.

[0020] like Figure 2 The image shows the Ni prepared in this embodiment. 0.5 Co 2.5 Raman spectra of O4 spinel catalyst and pure Co3O4 spinel, where A 1g The peak is attributed to Co in the CoO6 octahedron. 3+ -O 2- The stretching and contracting vibration of the bond. F 2g 1 Peaks and Co in CoO4 tetrahedra 2 + -O 2- It is related to bond Raman vibration. (Figure A) 1g The peak shows a significant redshift, F 2g 1 The peak did not shift, indicating that nickel ions selectively occupy octahedral sites in the spinel lattice, partially replacing the original Co. 3+ ion.

[0021] like Figure 3 As shown, this is the Ni prepared in this embodiment. 0.5 Co 2.5 Scanning electron microscopy (SEM) image of the O4 spinel catalyst, showing the Ni prepared in this example. 0.5 Co 2.5 The morphology of the O4 spinel catalyst is a bulk composed of aggregated nanospheres.

[0022] like Figure 4 As shown, this is the Ni prepared in this embodiment. 0.5 Co 2.5 The elemental distribution diagram of the O4 spinel catalyst shows that Ni, Co, and O are evenly distributed, indicating that Ni has been successfully doped into Co3O4.

[0023] Comparative Example 1Ni 0.75 Co 2.25Preparation of O4 catalyst: 23 mL of ethanol and 2 mL of deionized water were added to a 50 mL beaker as solvents. Then, 146 mg of nickel nitrate hexahydrate and 437 mg of cobalt nitrate hexahydrate were weighed and added to the beaker. The mixture was stirred on a magnetic stirrer until completely dissolved. Under vigorous stirring, 2.5 mL of 25% ammonia solution was rapidly added to the solution, which quickly became turbid. Stirring was continued for 10 minutes to form a homogeneous slurry. This slurry was transferred to the lining of a 50 mL high-pressure reactor, sealed, and reacted in an oven at 150 °C for 3 hours. After the reactor cooled naturally to room temperature, the product was centrifuged and washed five times with a 70% ethanol aqueous solution. The resulting solid was dried in a vacuum drying oven at 60 °C for 12 hours and ground to obtain a black precursor powder. This powder was placed in a tube furnace and calcined at 400 °C for 2 hours under air atmosphere at a rate of 5 °C / min to obtain Ni. 0.75 Co 2.25 O4 spinel catalyst.

[0024] Comparative Example 2Ni 0.375 Co 2.625 Preparation of O4 catalyst: 23 mL of ethanol and 2 mL of deionized water were added to a 50 mL beaker as solvents. Then, 73 mg of nickel nitrate hexahydrate and 509 mg of cobalt nitrate hexahydrate were weighed and added to the beaker. The mixture was stirred on a magnetic stirrer until completely dissolved. Under vigorous stirring, 2.5 mL of 25% ammonia solution was rapidly added to the solution, which quickly became turbid. Stirring was continued for 10 minutes to form a homogeneous slurry. This slurry was transferred to the lining of a 50 mL high-pressure reactor, sealed, and reacted in an oven at 150 °C for 3 hours. After the reactor cooled naturally to room temperature, the product was centrifuged and washed five times with a 70% ethanol aqueous solution. The resulting solid was dried in a vacuum drying oven at 60 °C for 12 hours and ground to obtain a black precursor powder. This powder was placed in a tube furnace and calcined at 400 °C for 2 hours under air atmosphere at a rate of 5 °C / min to obtain Ni. 0.375 Co 2.625 O4 spinel catalyst.

[0025] Comparative Example 3 Preparation of Co3O4 catalyst: 23 mL of ethanol and 2 mL of deionized water were added to a 50 mL beaker as solvents. Then, 582 mg of cobalt nitrate hexahydrate was weighed and added, and the mixture was stirred on a magnetic stirrer until completely dissolved. Under vigorous stirring, 2.5 mL of 25% ammonia solution was rapidly added to the solution, which quickly became turbid. Stirring continued for 10 minutes to form a homogeneous slurry. This slurry was transferred to the lining of a 50 mL high-pressure reactor, sealed, and reacted in an oven at 150 °C for 3 hours. After the reactor cooled naturally to room temperature, the product was centrifuged and washed five times with a 70% ethanol aqueous solution. The resulting solid was dried in a vacuum drying oven at 60 °C for 12 hours and ground to obtain a black precursor powder. This powder was placed in a tube furnace and calcined at 400 °C for 2 hours under air atmosphere at a rate of 5 °C / min to obtain the Co3O4 spinel catalyst.

[0026] To investigate the effect of different nickel contents on the performance of spinel catalysts, we compared the electrochemical performance of the spinel catalysts prepared in Example 1 and Comparative Examples 1-3. Figure 5 The figure shows the polarization curves of spinel catalysts with different Ni contents. The lower the voltage required for each catalyst to reach the same current density, the better the catalyst activity. This demonstrates that the Ni content does indeed affect the electrochemical performance of the spinel catalyst, and the Ni prepared in Example 1... 0.5 Co 2.5 O4 spinel catalyst reaches 10 mA / cm -2 The lowest voltage required at the current density indicates the best chlorine evolution activity. To further investigate the effects of reaction temperature, reaction time, and the contribution of nickel on catalyst preparation, spinel catalysts with different reaction temperatures, reaction times, and different element doping are also provided as controls.

[0027] Comparative Example 4 Ni with a hydrothermal temperature of 130℃ 0.75 Co 2.25Preparation of O4 catalyst: 23 mL of ethanol and 2 mL of deionized water were added to a 50 mL beaker as solvents. Then, 146 mg of nickel nitrate hexahydrate and 437 mg of cobalt nitrate hexahydrate were weighed and added to the beaker. The mixture was stirred on a magnetic stirrer until completely dissolved. Under vigorous stirring, 2.5 mL of 25% ammonia solution was rapidly added to the solution, which quickly became turbid. Stirring was continued for 10 minutes to form a homogeneous slurry. This slurry was transferred to the lining of a 50 mL high-pressure reactor, sealed, and reacted in an oven at 130 °C for 3 hours. After the reactor cooled naturally to room temperature, the product was centrifuged and washed five times with a 70% ethanol aqueous solution. The resulting solid was dried in a vacuum drying oven at 60 °C for 12 hours and ground to obtain a black precursor powder. This powder was placed in a tube furnace and calcined at 400 °C for 2 hours under air atmosphere at a rate of 5 °C / min, yielding Ni with a hydrothermal temperature of 130 °C. 0.75 Co 2.25 O4 spinel catalyst.

[0028] Comparative Example 5 Ni with a hydrothermal temperature of 170℃ 0.75 Co 2.25 Preparation of O4 catalyst: 23 mL of ethanol and 2 mL of deionized water were added to a 50 mL beaker as solvents. Then, 146 mg of nickel nitrate hexahydrate and 437 mg of cobalt nitrate hexahydrate were weighed and added to the beaker. The mixture was stirred on a magnetic stirrer until completely dissolved. Under vigorous stirring, 2.5 mL of 25% ammonia solution was rapidly added to the solution, which quickly became turbid. Stirring was continued for 10 minutes to form a homogeneous slurry. This slurry was transferred to the lining of a 50 mL high-pressure reactor, sealed, and reacted in an oven at 170 °C for 3 hours. After the reactor cooled naturally to room temperature, the product was centrifuged and washed five times with a 70% ethanol aqueous solution. The resulting solid was dried in a vacuum drying oven at 60 °C for 12 hours and ground to obtain a black precursor powder. This powder was placed in a tube furnace and calcined at 400 °C for 2 hours under air atmosphere at a rate of 5 °C / min, yielding Ni with a hydrothermal temperature of 170 °C. 0.75 Co 2.25 O4 spinel catalyst.

[0029] Comparative Example 6 Ni with a hydrothermal time of 1 hour 0.75 Co 2.25Preparation of O4 catalyst: 23 mL of ethanol and 2 mL of deionized water were added to a 50 mL beaker as solvents. Then, 146 mg of nickel nitrate hexahydrate and 437 mg of cobalt nitrate hexahydrate were weighed and added to the beaker. The mixture was stirred on a magnetic stirrer until completely dissolved. Under vigorous stirring, 2.5 mL of 25% ammonia solution was rapidly added to the solution, which quickly became turbid. Stirring was continued for 10 minutes to form a homogeneous slurry. This slurry was transferred to the lining of a 50 mL high-pressure reactor, sealed, and reacted in an oven at 150 °C for 1 hour. After the reactor cooled naturally to room temperature, the product was centrifuged and washed five times with a 70% ethanol aqueous solution. The resulting solid was dried in a vacuum drying oven at 60 °C for 12 hours and ground to obtain a black precursor powder. This powder was placed in a tube furnace and calcined at 400 °C for 2 hours under air atmosphere at a rate of 5 °C / min, yielding Ni with a hydrothermal time of 1 hour. 0.75 Co 2.25 O4 spinel catalyst.

[0030] Comparative Example 7 Ni with a hydrothermal time of 5 hours 0.75 Co 2.25 Preparation of O4 catalyst: 23 mL of ethanol and 2 mL of deionized water were added to a 50 mL beaker as solvents. Then, 146 mg of nickel nitrate hexahydrate and 437 mg of cobalt nitrate hexahydrate were weighed and added to the beaker. The mixture was stirred on a magnetic stirrer until completely dissolved. Under vigorous stirring, 2.5 mL of 25% ammonia solution was rapidly added to the solution, which quickly became turbid. Stirring was continued for 10 minutes to form a homogeneous slurry. This slurry was transferred to the lining of a 50 mL high-pressure reactor, sealed, and reacted in an oven at 150 °C for 5 hours. After the reactor cooled naturally to room temperature, the product was centrifuged and washed five times with a 70% ethanol aqueous solution. The resulting solid was dried in a vacuum drying oven at 60 °C for 12 hours and ground to obtain a black precursor powder. This powder was placed in a tube furnace and calcined at 400 °C for 2 hours under air atmosphere at a rate of 5 °C / min, yielding Ni with a hydrothermal time of 5 h. 0.75 Co 2.25 O4 spinel catalyst.

[0031] Comparative Example 8 Mn 0.5 Co 2.5Preparation of O4 catalyst: 23 mL of ethanol and 2 mL of deionized water were added to a 50 mL beaker as solvents. Then, 84 mg of manganese nitrate tetrahydrate and 485 mg of cobalt nitrate hexahydrate were weighed and added. The mixture was stirred on a magnetic stirrer until completely dissolved. Under vigorous stirring, 2.5 mL of 25% ammonia solution was rapidly added to the solution, which quickly became turbid. Stirring was continued for 10 minutes to form a homogeneous slurry. This slurry was transferred to the lining of a 50 mL high-pressure reactor, sealed, and reacted in an oven at 150 °C for 3 hours. After the reactor cooled naturally to room temperature, the product was centrifuged and washed five times with a 70% ethanol aqueous solution. The resulting solid was dried in a vacuum drying oven at 60 °C for 12 hours and ground to obtain a black precursor powder. This powder was placed in a tube furnace and calcined at 400 °C for 2 hours under air atmosphere at a rate of 5 °C / min to obtain Mn. 0.5 Co 2.5 O4 spinel catalyst.

[0032] Comparative Example 9 Fe 0.5 Co 2.5 Preparation of O4 catalyst: 23 mL of ethanol and 2 mL of deionized water were added to a 50 mL beaker as solvents. Then, 135 mg of ferric nitrate nonahydrate and 485 mg of cobalt nitrate hexahydrate were weighed and added. The mixture was stirred on a magnetic stirrer until completely dissolved. Under vigorous stirring, 2.5 mL of 25% ammonia solution was rapidly added to the solution, which quickly became turbid. Stirring was continued for 10 minutes to form a homogeneous slurry. This slurry was transferred to the lining of a 50 mL high-pressure reactor, sealed, and reacted in an oven at 150 °C for 3 hours. After the reactor cooled naturally to room temperature, the product was centrifuged and washed five times with a 70% ethanol aqueous solution. The resulting solid was dried in a vacuum drying oven at 60 °C for 12 hours and ground to obtain a black precursor powder. This powder was placed in a tube furnace and calcined at 400 °C for 2 hours under air atmosphere at a rate of 5 °C / min to obtain Fe. 0.5 Co 2.5 O4 spinel catalyst.

[0033] Comparative Example 10 Cu 0.5 Co 2.5Preparation of O4 catalyst: 23 mL of ethanol and 2 mL of deionized water were added to a 50 mL beaker as solvents. Then, 81 mg of copper nitrate trihydrate and 485 mg of cobalt nitrate hexahydrate were weighed and added. The mixture was stirred on a magnetic stirrer until completely dissolved. Under vigorous stirring, 2.5 mL of 25% ammonia water was rapidly added to the solution, which quickly became turbid. Stirring was continued for 10 minutes to form a homogeneous slurry. This slurry was transferred to the lining of a 50 mL high-pressure reactor, sealed, and reacted in an oven at 150 °C for 3 hours. After the reactor cooled naturally to room temperature, the product was centrifuged and washed five times with a 70% ethanol aqueous solution. The resulting solid was dried in a vacuum drying oven at 60 °C for 12 hours and ground to obtain a black precursor powder. This powder was placed in a tube furnace and calcined at 400 °C for 2 hours under air atmosphere at a rate of 5 °C / min to obtain Cu. 0.5 Co 2.5 O4 spinel catalyst.

[0034] Comparative Example 11 Zn 0.5 Co 2.5 Preparation of O4 catalyst: 23 mL of ethanol and 2 mL of deionized water were added to a 50 mL beaker as solvents. Then, 99 mg of copper nitrate trihydrate and 485 mg of cobalt nitrate hexahydrate were weighed and added. The mixture was stirred on a magnetic stirrer until completely dissolved. Under vigorous stirring, 2.5 mL of 25% ammonia solution was rapidly added to the solution, which quickly became turbid. Stirring was continued for 10 minutes to form a homogeneous slurry. This slurry was transferred to the lining of a 50 mL high-pressure reactor, sealed, and reacted in an oven at 150 °C for 3 hours. After the reactor cooled naturally to room temperature, the product was centrifuged and washed five times with a 70% ethanol aqueous solution. The resulting solid was dried in a vacuum drying oven at 60 °C for 12 hours and ground to obtain a black precursor powder. This powder was placed in a tube furnace and calcined at 400 °C for 2 hours under air atmosphere at a rate of 5 °C / min to obtain Zn. 0.5 Co 2.5 O4 spinel catalyst.

[0035] The activity and chlorine selectivity of the spinel catalysts prepared in Comparative Examples 1 and 1-11 are shown in Table 1.

[0036] Table 1. Activity and Cl2 selectivity of the spinel catalysts prepared in Example 1 and Comparative Examples 1-11

[0037] Table 1 is a summary table of the activity and Cl2 selectivity of the catalysts prepared in Example 1 and Comparative Examples 1-11, η 10 This indicates that the catalyst's current density reaches 10 mA·cm⁻¹. -2The lowest required overpotential and voltage indicate the best chlorine evolution activity. Example 1 showed the best performance with an overpotential of 88 mV, and also exhibited the highest Cl2 selectivity of 96.5%, demonstrating optimal chlorine evolution. Furthermore, Table 1 clearly shows that reaction temperature, reaction time, specific dopant elements, and doping amounts all significantly affect the activity and chlorine selectivity of the spinel catalyst.

[0038] Finally, it should be noted that the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make further changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0039] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various changes and improvements without departing from the concept of the technical solution of this application, and these all fall within the scope of protection of this application.

Claims

1. A spinel-type catalyst for electrocatalytic production of chlorine, characterized in that, The catalyst is a nickel-doped cobalt spinel oxide, with a general chemical formula of Ni x Co 3-x O4, wherein x is in the range of 0.4-0.6, the crystal structure belongs to a cubic spinel structure, nickel ions selectively occupy octahedral sites in the spinel lattice, and partially replace original Co 3+ ions.

2. The spinel catalyst of claim 1, wherein the spinel catalyst has a spinel structure. x is 0.

5.

3. The method for producing a spinel catalyst according to claim 1 or 2, characterized by, The method comprises the following steps: (1) Dissolve nickel nitrate and cobalt nitrate in a mixed solvent of ethanol and deionized water according to the general formula of claim 1 or 2, and after complete dissolution, quickly add ammonia water to the solution under vigorous stirring, continue stirring for 5-20 minutes after the solution turns turbid to form a uniform slurry; (2) Transfer the slurry obtained in step (1) into a high-pressure reaction kettle, seal it and place it in an oven for hydrothermal reaction at 140-160°C for 3-5 hours; (3) After the reaction kettle is naturally cooled to room temperature, centrifugal separation, washing, drying and grinding are performed on the product in the reaction kettle to obtain a black precursor powder; (4) The black precursor powder was placed in a tube furnace, calcined at 300-500°C for 2 hours under air atmosphere with a heating rate of 5°C / min, to obtain nickel-doped cobalt spinel oxide Ni x Co 3-x O4.

4. The production method according to claim 3, wherein The molar ratio of nickel nitrate to cobalt nitrate in step (1) is 1:

5.

5. The production method according to claim 3, wherein The volume ratio of ethanol to deionized water in step (1) is 10-20:

1.

6. The production method according to claim 3, wherein The concentration of ammonia water in step (1) is 25wt%, and the amount is 10-20% of the total volume of the reaction system.

7. Use of the spinel-type catalyst of claim 1 or 2 as an electrocatalyst in the electrocatalytic preparation of chlorine.

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