Nickel oxide-based iron-iridium double-electrodeposition catalyst, preparation method and application thereof

Abstract

The application discloses a nickel oxide-based iron-iridium double-electrodeposition catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalytic materials. ‑ The nickel oxide material is prepared into a nickel oxide working electrode, a mixed solution of an iron precursor, an iridium precursor and OH ‑ is used as an electrolyte, and iron-iridium bimetal is deposited on the nickel oxide working electrode through electrochemical deposition, so as to obtain the nickel oxide-based iron-iridium double-electrodeposition catalyst. The preparation method provided by the application realizes the multi-scale dispersion of iron and iridium two metal elements on the surface of the nickel oxide carrier, and the multi-scale structure not only provides rich catalytic active sites, so that the catalyst can more efficiently adsorb and activate reactants in a reaction process, but also significantly enhances the electron transfer efficiency, thereby improving the catalytic activity of the catalyst. In addition, the synergistic effect of iron and iridium optimizes the electronic structure of the catalyst, and further improves the catalytic performance of the catalyst.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically to a nickel oxide-based iron-iridium dual electrodeposition catalyst, its preparation method, and its application. Background Technology

[0002] Electrolysis of water to produce hydrogen is a highly efficient and clean energy conversion technology that converts electrical energy into chemical energy, providing crucial support for achieving a carbon-neutral energy structure transition. The oxygen evolution reaction (OER), the anodic reaction in water electrolysis, involves the generation of oxygen and is a key step in achieving efficient water electrolysis. Highly efficient and stable electrocatalysts are crucial for the large-scale application of OER technology because they can significantly reduce the overpotential of the reaction and improve the reaction rate and stability. Nickel-based materials, due to their lattice oxygen mechanism, exhibit unique dynamic structural changes in the water electrolysis reaction, forming surfaces rich in oxygen vacancies and active sites. They also possess good conductivity, stability, and low cost, making them ideal carriers for constructing highly efficient electrocatalysts.

[0003] In electrocatalytic reactions, the electronic and geometric structures of the catalytic interface significantly influence catalytic activity and selectivity. Current chemical synthesis methods face numerous challenges in preparing these multi-scale catalytic interfaces. Traditional methods struggle to achieve continuous control over the interface size, involve complex reaction conditions, and result in catalysts with insufficient active sites, leading to poor catalytic performance and stability. The high surface energy of metal species facilitates the aggregation of metal sites, thus hindering effective charge transfer and consequently reducing catalytic efficiency. Summary of the Invention

[0004] This invention provides a nickel oxide-based iron-iridium double electrodeposition catalyst, its preparation method, and its application. It effectively solves the technical problems of insufficient reactive sites in catalysts prepared by existing synthesis methods, resulting in poor catalytic performance and stability; and the problem of metal site aggregation affecting effective charge transfer, thereby reducing catalytic efficiency. At the same time, it provides a nickel oxide-based iron-iridium double electrodeposition catalyst with high catalytic activity and excellent catalytic stability.

[0005] The first objective of this invention is to provide a method for preparing a nickel oxide-based iron-iridium dual electrodeposition catalyst, comprising the following steps:

[0006] Using DL-α-alanine as a ligand, with Ni 2+ The source forms a Ni-alanine complex, which is then pyrolyzed in air at 550℃~620℃ to decompose the complex in the Ni-alanine complex and obtain nickel oxide material.

[0007] The nickel oxide material was prepared as a nickel oxide working electrode, using an iron precursor, an iridium precursor, and OH. －The mixed solution of the source is used as the electrolyte. Through electrochemical deposition, an iron-iridium bimetal is deposited on the nickel oxide working electrode to obtain a nickel oxide-based iron-iridium bimetallic electrodeposition catalyst.

[0008] In the electrolyte, the molar ratio of iridium precursor to iron precursor is 1:0.2~2.

[0009] In a preferred embodiment, the molar ratio of iridium precursor to iron precursor in the electrolyte is 1:1.

[0010] In a preferred embodiment, the electrochemical deposition employs a chronoamperometry method with a voltage of 5V~7V and a deposition time of 8000s~12000s. More preferably, the electrochemical deposition employs a chronoamperometry method with a voltage of 6V and a deposition time of 10000s.

[0011] As a preferred embodiment, the nickel oxide working electrode is electrochemically activated before electrochemical deposition, specifically by using a standard three-electrode electrode to deposit OH- ions. － In the solution, short pulses of cathode potential of -2V to -1.5V (0.5s to 1.5s) and short pulses of anode potential of 1.5V to 2V (0.5s to 1.5s) are sequentially applied to the nickel oxide working electrode. More preferably, a short pulse of cathode potential of -2V (1s) and a short pulse of anode potential of 2V (1s) are sequentially applied to the nickel oxide working electrode.

[0012] In a preferred embodiment, one cycle consists of one short pulse at the cathode potential and one short pulse at the anode potential, and the cycle is repeated 40 to 60 times. More preferably, the cycle is repeated 50 times.

[0013] In a preferred embodiment, the nickel oxide working electrode is prepared by ultrasonically mixing the nickel oxide material, ethanol, and Nafion, and then drop-coating the mixture onto carbon paper to obtain a nickel oxide material loading of 0.8 mg / cm³. 2 ~2.3mg / cm 2 A nickel oxide working electrode. More preferably, the nickel oxide material, ethanol, and Nafion are ultrasonically mixed and drop-coated onto carbon paper to obtain a nickel oxide material loading of 1 mg / cm³. 2 Nickel oxide working electrode.

[0014] As a preferred embodiment, the Ni 2+ The molar ratio of the source to DL-α-alanine is 1:4~5.

[0015] In a preferred embodiment, the pyrolysis time is 1.5 h to 3 h. More preferably, the pyrolysis time is 2 h.

[0016] A second objective of this invention is to provide a nickel oxide-based iron-iridium dual electrodeposition catalyst, prepared using any of the methods described above.

[0017] A third objective of this invention is to provide an application of the above-mentioned nickel oxide-based iron-iridium double electrodeposition catalyst in catalytic water electrolysis.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] This invention provides a method for preparing a nickel oxide-based iron-iridium dual electrodeposition catalyst, using DL-α-alanine as a ligand and Ni 2+ A Ni-alanine complex is formed from the source and then pyrolyzed in air at 550℃~620℃ to decompose the complex in the Ni-alanine complex, yielding a nickel oxide material. This nickel oxide material is then used to prepare a nickel oxide working electrode, using an iron precursor, an iridium precursor, and OH... - The mixed solution of the source is used as the electrolyte. Through electrochemical deposition, an iron-iridium bimetallic compound is deposited on the nickel oxide working electrode to obtain a nickel oxide-based iron-iridium bimetallic electrodeposition catalyst. The preparation method provided by this invention achieves multi-scale dispersion of iron and iridium on the surface of a nickel oxide support. By adjusting the amounts of iron and iridium precursors, multi-scale construction of different metal catalytic interfaces can be achieved. This multi-scale structure not only provides abundant catalytic active sites, enabling the catalyst to more efficiently adsorb and activate reactants during the reaction, but also significantly enhances electron transfer efficiency, thereby improving the catalyst's catalytic activity. Furthermore, the synergistic effect of iron and iridium optimizes the electronic structure of the catalyst, further enhancing its catalytic performance.

[0020] The nickel oxide-based iron-iridium dual electrodeposition catalyst provided by this invention possesses a high specific surface area, thanks to surface defects introduced by applying a pulse to nickel oxide. These defects promote the formation of a rich porous structure on the nickel oxide support. This porous structure not only increases the specific surface area of ​​the catalyst but also significantly enhances its adsorption capacity for reactants, thereby improving catalytic activity. Furthermore, the coordination environment of iron and iridium allows for efficient charge transfer, enabling the catalyst to optimize its electronic structure, thus exhibiting higher efficiency and stability in electrocatalytic reactions.

[0021] The method for preparing nickel oxide-based iron-iridium dual electrodeposition catalysts provided by this invention controls the concentration of the metal precursor and the electrochemical deposition time to adjust the form of metal deposition on nickel oxide, thereby preparing a multi-scale deposition catalytic interface ranging from isolated single atoms, atomic clusters to nanoparticles.

[0022] The preparation method of this invention is universal and applicable to various metal elements. It allows for precise control of the catalytic interface scale through precise regulation of electrochemical deposition conditions. Therefore, the catalyst prepared by this invention can promote activities related to the electrocatalytic splitting of water, thereby improving the catalyst's catalytic activity. Furthermore, the preparation method of this invention is simple to operate, requires minimal equipment, and offers highly controllable operation, further improving the catalyst yield ratio. It is very suitable for large-scale production and has significant value. Attached Figure Description

[0023] Figure 1 The images shown are aberration-corrected high-angle annular dark-field scanning transmission electron microscope images of the nickel oxide-based iron-iridium double electrodeposition catalyst prepared in Example 1 of this invention. In the images, (a) is at 50 nm, (b) is at 500 nm, (c) is the distribution map of Ir, (d) is the distribution map of O, and (e) is the distribution map of Ni.

[0024] Figure 2 The linear sweep voltammetry curves of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 of this invention for the OER reaction are shown below, wherein NiO x For Comparative Example 1, NiO x -Fe is used in comparative example 2, NiO x -Ir is for comparative example 3, NiO x -IrFe is from Example 1, NiO x -IrFe 0.2 Example 2, NiO x -IrFe2 is from Example 3.

[0025] Figure 3 The catalysts prepared for Examples 1-2 and Comparative Examples 1-3 of this invention were subjected to an ampere reaction at 10 mA·cm⁻¹. -2 The overpotential diagram required for the OER reaction in electrocatalytic water splitting, where NiO... x For Comparative Example 1, NiO x -Fe is used in comparative example 2, NiO x -Ir is for comparative example 3, NiO x -IrFe is from Example 1, NiO x -IrFe 0.2 Example 2.

[0026] Figure 4 This is a Tafel slope diagram of the OER reaction of the catalysts prepared in Examples 1-2 and Comparative Examples 1-3 of this invention for electrocatalytic water splitting, wherein NiO x For Comparative Example 1, NiO x -Fe is used in comparative example 2, NiO x-Ir is for comparative example 3, NiO x -IrFe is from Example 1, NiO x -IrFe 0.2 Example 2.

[0027] Figure 5 The electrochemically active surface area diagrams obtained by cyclic voltammetry for the OER reaction of the catalysts prepared in Examples 1-2 and Comparative Examples 1-3 of this invention during the electrocatalytic water splitting process are shown in the figure. NiO x For Comparative Example 1, NiO x -Fe is used in comparative example 2, NiO x -Ir is for comparative example 3, NiO x -IrFe is from Example 1, NiO x -IrFe 0.2 Example 2.

[0028] Figure 6 The catalysts prepared for Examples 1-2 and Comparative Examples 1-3 of this invention were subjected to an ampere reaction at 10 mA·cm⁻¹. -2 Stability test results of the OER reaction during electrocatalytic water splitting, where NiO... x For Comparative Example 1, NiO x -Fe is used in comparative example 2, NiO x -Ir is for comparative example 3, NiO x -IrFe is from Example 1, NiO x -IrFe 0.2 Example 2. Detailed Implementation

[0029] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention is further described below with reference to specific embodiments. However, the embodiments are not intended to limit the invention. Unless otherwise specified, the following test methods and detection methods are conventional methods; unless otherwise specified, the reagents and raw materials are commercially available.

[0030] Existing chemical synthesis methods for catalysts suffer from difficulties in continuously controlling the catalytic interface size, complex reaction conditions, insufficient active sites, and poor catalytic performance and stability. The high surface energy of metal species leads to the easy aggregation of metal sites, thus affecting effective charge transfer and reducing catalytic efficiency. To address these technical problems, this invention provides a nickel oxide-based iron-iridium dual electrodeposition catalyst, its preparation method, and its applications.

[0031] The technical solution of the present invention will be described in detail below.

[0032] This invention provides a method for preparing a nickel oxide-based iron-iridium dual electrodeposition catalyst, comprising the following steps:

[0033] S1, with DL-α-alanine as a ligand, reacts with Ni 2+ The source forms a Ni-alanine complex, which is then pyrolyzed in air at 550℃~620℃ to decompose the complex in the Ni-alanine complex and obtain nickel oxide material.

[0034] S2, the nickel oxide material is prepared as a nickel oxide working electrode, using an iron precursor, an iridium precursor, and OH... - The mixed solution of the source is used as the electrolyte. Through electrochemical deposition, an iron-iridium bimetal is deposited on the nickel oxide working electrode to obtain a nickel oxide-based iron-iridium bimetallic electrodeposition catalyst.

[0035] In the electrolyte, the molar ratio of iridium precursor to iron precursor is 1:0.2~2.

[0036] In the above technical solution, an iron-iridium bimetallic compound is deposited on the nickel oxide working electrode via electrochemical deposition. By adjusting the amounts of iron and iridium precursors, a multi-scale construction of different metal catalytic interfaces can be achieved. This multi-scale structure not only provides abundant catalytic active sites, enabling the catalyst to more efficiently adsorb and activate reactants during the reaction, but also significantly enhances electron transfer efficiency, thereby improving the catalyst's catalytic activity. Furthermore, the coordination environment of iron and iridium allows for effective charge transfer, which enables the catalyst to optimize its electronic structure, resulting in higher efficiency and stability in electrocatalytic reactions, further enhancing its catalytic performance.

[0037] Regarding the molar ratio of iridium to iron precursors, when the ratio is within the range of 1:0.2 to 2, the improved catalyst performance stems from the synergistic effect of the two. When the molar ratio of iron precursor is below 0.2, the iron content is insufficient, making it difficult to form an effective two-site synergy, resulting in limited improvement in catalytic activity and insignificant improvement in stability; iron only partially modifies the electronic structure of iridium. Conversely, when the molar ratio of iron precursor exceeds 2, excess iron forms an oxide film covering the active sites, reducing the exposed area, hindering iridium dispersion, altering the reaction pathway, weakening the dominant role of iridium, and leading to a decrease in catalytic efficiency. Only within the range of 1:0.2 to 2 can the contribution of iron to stability and iridium to activity be balanced, allowing the catalyst to achieve optimal performance in terms of overpotential and stability.

[0038] To further improve the catalytic performance of the catalyst, the molar ratio of iron precursor to iridium precursor in the electrolyte is 1:1. This 1:1 molar ratio is achieved by optimizing Ni... 3+Concentration, metal coordination environment, and interface scale can achieve a synergistic improvement in catalytic activity, kinetics, and stability. However, when the molar ratio is 1:0.2 or 1:2, the synergistic effect is slightly unbalanced due to insufficient or excessive single component, resulting in inferior performance.

[0039] To balance the activity and stability of the catalyst, the electrochemical deposition employs a chronoamperometry method with a voltage of 5V~7V and a deposition time of 8000s~12000s. More preferably, the electrochemical deposition uses a chronoamperometry method with a voltage of 6V and a deposition time of 10000s. In electrochemical deposition, voltage and time are the core parameters for controlling the catalytic interface. If the voltage is below 5V and the deposition time is less than 8000s, the driving force for metal ion reduction is insufficient, the deposition amount is significantly reduced, the active site density is low, and the active sites tend to exist in single-atom form, lacking cluster / nanoparticle synergy, resulting in weak metal-support interaction and poor stability. Conversely, when the voltage is above 7V and the deposition time is greater than 12000s, the metal ion reduction is too rapid, easily agglomerating to form nanoparticles covering the active sites, destroying the defective structure of the support, and Ni 3+ As the concentration decreases, side reactions intensify, and the catalyst activity and stability deteriorate simultaneously.

[0040] To achieve multi-scale catalytic interface regulation, the nickel oxide working electrode is electrochemically activated before electrochemical deposition. Specifically, a standard three-electrode system is used to deposit OH-containing... － In the solution, short pulses of cathode potential (0.5s~1.5s, -2V~-1.5V) and short pulses of anode potential (0.5s~1.5s, 1.5V~2V) are sequentially applied to the nickel oxide working electrode. More preferably, a short pulse of cathode potential (1s, -2V) and a short pulse of anode potential (1s, 2V) are sequentially applied to the nickel oxide working electrode. Pulse activation is achieved through electrochemical reconstruction in NiO. x Introducing high-density defects and active sites into the surface lays the foundation for uniform deposition of metal atoms and strong MSI formation, which is a core prerequisite for achieving multi-scale catalytic interface regulation. Deviations from this parameter range will lead to insufficient defects or damage to the support structure, thereby affecting the metal deposition quality and catalytic performance.

[0041] In a preferred embodiment, one short pulse at the cathode potential and one short pulse at the anode potential constitute one cycle, and the cycle is repeated 40 to 60 times. More preferably, the cycle is repeated 50 times. If the number of repetitions is less than 40, the pulse cycle count will be insufficient to fully penetrate NiO. x Surface-constructed defect structures. This leads to surface oxygen vacancies and nitrogen deposits. 3+A low number of active sites hinders the anchoring of subsequent metal atoms, resulting in insufficient and uneven metal deposition, low catalyst active site density, and limited improvement in catalytic performance. Furthermore, when the number of repetitions exceeds 60, excessive pulse activation can negatively impact NiO. x Damage to the crystal lattice structure can cause lattice collapse, affecting the conductivity and stability of the support. It can also lead to excessive generation of surface defects, which in turn damages the interface structure, reduces the uniformity of metal deposition, and consequently has an adverse effect on the activity and stability of the catalyst.

[0042] In a preferred embodiment, the nickel oxide working electrode is prepared by ultrasonically mixing the nickel oxide material, ethanol, and Nafion, and then drop-coating the mixture onto carbon paper to obtain a nickel oxide material loading of 0.8 mg / cm³. 2 ~2.3mg / cm 2 A nickel oxide working electrode. More preferably, the nickel oxide material, ethanol, and Nafion are ultrasonically mixed and drop-coated onto carbon paper to obtain a nickel oxide material loading of 1 mg / cm³. 2 The nickel oxide working electrode. When the loading is 1 mg / cm³... 2 At that time, NiO x Uniformly distributed on the surface of carbon paper ensures sufficient active sites, such as Ni. 3+ Oxygen vacancies can participate in electrocatalytic reactions, while avoiding the obstruction of ion diffusion or the aggregation and covering of sites due to excessive loading, and are easy to replicate in experiments.

[0043] As a preferred embodiment, the Ni 2+ The molar ratio of nickel ions to DL-α-alanine is 1:4~5. When preparing the complex, if the amount of DL-α-alanine is insufficient, i.e., less than the specified amount of 4, the nickel ion coordination will be unsaturated, and NiO will... x Ni has few lattice defects 3+ The low proportion of DL-α-alanine results in weak *OH adsorption capacity, increased OER overpotential, and easy agglomeration of metal deposits. If the molar ratio of DL-α-alanine is greater than the limit of 5, alanine is in excess, and residual carbon covers NiO after calcination. x On the surface, conductivity decreases, OER overpotential increases, stability decreases, and electrochemical deposition uniformity is also compromised. This range allows for a balance between coordination saturation and defect control, achieving performance optimization.

[0044] In a preferred embodiment, the pyrolysis time is 1.5 h to 3 h. More preferably, the pyrolysis time is 2 h. If the pyrolysis time is less than 1.5 h, the Ni-alanine complex decomposes incompletely, leaving residual organic ligands, which leads to NiO... x Incomplete crystal transformation. Furthermore, a pyrolysis time exceeding 3 hours will cause NiO to... xExcessive grain growth reduces the specific surface area, significantly decreasing the catalyst's activity and stability.

[0045] The invention will now be described in detail through the following embodiments and comparative examples.

[0046] Example 1

[0047] A method for preparing a nickel oxide-based iron-iridium dual electrodeposition catalyst includes the following steps:

[0048] S1. Weigh 2.5 mmol (0.622 g) of Ni(CH3COO)2·4H2O and 11.2 mmol (89.09 g) of DL-α-alanine into a beaker according to a molar ratio of nickel acetate tetrahydrate to DL-α-alanine of 1:4.5. Add 10 mL of deionized water and stir at 750 rpm for 10 min. Add 140 mL of anhydrous ethanol and continue stirring at 750 rpm for 5 min to form a blue suspension. Centrifuge and wash the solid twice with deionized water and twice with ethanol. Collect the sediment and dry it overnight in air at 60 °C. After drying, allow it to cool naturally to room temperature. Remove the dried sample and grind it into powder in an agate mortar for 15 min. Place the powder in a quartz boat and then place it in a tube furnace at a flow rate of 200 mL / min. -1 In air atmosphere, at 1℃·min -1 The temperature is rapidly increased to 600℃, held at that temperature for 2 hours, and then allowed to cool naturally to obtain a nickel oxide material, denoted as NiO. x powder.

[0049] S2, weigh 0.25 mg NiO according to the ratio of 1 mg: 200 µL: 10 µL. x NiO powder, 50 µL of anhydrous ethanol, and 2.5 µL of Nafion were dispersed in a centrifuge tube by sonication for 0.75 h. The dispersion was then evenly distributed using a pipette onto 0.5 cm × 0.5 cm carbon paper coated with a microporous carbon layer. The mixture was then allowed to dry overnight in air to obtain NiO. x The powder loading was 1.0 mg·cm³. -2 The nickel oxide working electrode, denoted as NiO x Electrode sheet.

[0050] S3 employs a standard three-electrode system, using a carbon rod as the counter electrode, an Hg / HgO electrode as the reference electrode, and NiO... x The electrode plate serves as the working electrode. The working electrode is activated by pulsed potential in a 1M potassium hydroxide solution by sequentially applying a -2V cathode potential short pulse for 1 second, followed by a 2V anode potential short pulse for 1 second, and repeating this process 50 times for NiO. xBy introducing surface defects into the electrode sheet, an activated nickel oxide working electrode is obtained.

[0051] S4, a mixed solution containing 1M potassium hydroxide, 100µM Fe(NO3)3·9H2O, and 100µM IrCl4·xH2O was prepared as the electrolyte. Electrochemical deposition was performed on the activated nickel oxide working electrode at 6V for 10000s to obtain a nickel oxide-based iron-iridium dual electrodeposition catalyst, denoted as NiO. x -IrFe.

[0052] Example 2

[0053] A method for preparing a nickel oxide-based iron-iridium dual electrodeposition catalyst includes the following steps:

[0054] S1. Weigh 2.5 mmol (0.622 g) of Ni(CH3COO)2·4H2O and 11.2 mmol (89.09 g) of DL-α-alanine into a beaker according to a molar ratio of nickel acetate tetrahydrate to DL-α-alanine of 1:4.5. Add 10 mL of deionized water and stir at 750 rpm for 10 min. Add 140 mL of anhydrous ethanol and continue stirring at 750 rpm for 5 min to form a blue suspension. Centrifuge and wash the solid twice with deionized water and twice with ethanol. Collect the sediment and dry it overnight in air at 60 °C. After drying, allow it to cool naturally to room temperature. Remove the dried sample and grind it into powder in an agate mortar for 15 min. Place the powder in a quartz boat and then place it in a tube furnace at a flow rate of 200 mL / min. -1 In air atmosphere, at 1℃·min -1 The temperature is rapidly increased to 600℃, held at that temperature for 2 hours, and then allowed to cool naturally to obtain a nickel oxide material, denoted as NiO. x powder.

[0055] S2, weigh 0.25 mg NiO according to the ratio of 1 mg: 200 µL: 10 µL. x NiO powder, 50 µL of anhydrous ethanol, and 2.5 µL of Nafion were dispersed in a centrifuge tube by sonication for 0.75 h. The dispersion was then evenly distributed using a pipette onto 0.5 cm × 0.5 cm carbon paper coated with a microporous carbon layer. The mixture was then allowed to dry overnight in air to obtain NiO. x The powder loading was 1.0 mg·cm³. -2 The nickel oxide working electrode, denoted as NiO x Electrode sheet.

[0056] S3 employs a standard three-electrode system, using a carbon rod as the counter electrode, an Hg / HgO electrode as the reference electrode, and NiO... xThe electrode plate serves as the working electrode. The working electrode is activated by pulsed potential in a 1M potassium hydroxide solution by sequentially applying a -2V cathode potential short pulse for 1 second, followed by a 2V anode potential short pulse for 1 second, and repeating this process 50 times for NiO. x By introducing surface defects into the electrode sheet, an activated nickel oxide working electrode is obtained.

[0057] S4, a mixed solution containing 1M potassium hydroxide, 20µM Fe(NO3)3·9H2O, and 100µM IrCl4·xH2O was prepared as the electrolyte. Electrochemical deposition was performed on the activated nickel oxide working electrode at 6V for 10000s to obtain a nickel oxide-based iron-iridium dual electrodeposition catalyst, denoted as NiO. x -IrFe 0.2 .

[0058] Example 3

[0059] A method for preparing a nickel oxide-based iron-iridium dual electrodeposition catalyst includes the following steps:

[0060] S1. Weigh 2.5 mmol (0.622 g) of Ni(CH3COO)2·4H2O and 11.2 mmol (89.09 g) of DL-α-alanine into a beaker according to a molar ratio of nickel acetate tetrahydrate to DL-α-alanine of 1:4.5. Add 10 mL of deionized water and stir at 750 rpm for 10 min. Add 140 mL of anhydrous ethanol and continue stirring at 750 rpm for 5 min to form a blue suspension. Centrifuge and wash the solid twice with deionized water and twice with ethanol. Collect the sediment and dry it overnight in air at 60 °C. After drying, allow it to cool naturally to room temperature. Remove the dried sample and grind it into powder in an agate mortar for 15 min. Place the powder in a quartz boat and then place it in a tube furnace at a flow rate of 200 mL / min. -1 In air atmosphere, at 1℃·min -1 The temperature is rapidly increased to 600℃, held at that temperature for 2 hours, and then allowed to cool naturally to obtain a nickel oxide material, denoted as NiO. x powder.

[0061] S2, weigh 0.25 mg NiO according to the ratio of 1 mg: 200 µL: 10 µL. x NiO powder, 50 µL of anhydrous ethanol, and 2.5 µL of Nafion were dispersed in a centrifuge tube by sonication for 0.75 h. The dispersion was then evenly distributed using a pipette onto 0.5 cm × 0.5 cm carbon paper coated with a microporous carbon layer. The mixture was then allowed to dry overnight in air to obtain NiO. x The powder loading was 1.0 mg·cm³. -2The nickel oxide working electrode, denoted as NiO x Electrode sheet.

[0062] S3 employs a standard three-electrode system, using a carbon rod as the counter electrode, an Hg / HgO electrode as the reference electrode, and NiO... x The electrode plate serves as the working electrode. The working electrode is activated by pulsed potential in a 1M potassium hydroxide solution by sequentially applying a -2V cathode potential short pulse for 1 second, followed by a 2V anode potential short pulse for 1 second, and repeating this process 50 times for NiO. x By introducing surface defects into the electrode sheet, an activated nickel oxide working electrode is obtained.

[0063] S4, a mixed solution containing 1M potassium hydroxide, 200µM Fe(NO3)3·9H2O, and 100µM IrCl4·xH2O was prepared as the electrolyte. Electrochemical deposition was performed on the activated nickel oxide working electrode at 6V for 10000s to obtain a nickel oxide-based iron-iridium dual electrodeposition catalyst, denoted as NiO. x -IrFe2.

[0064] Example 4

[0065] A method for preparing a nickel oxide-based iron-iridium dual electrodeposition catalyst includes the following steps:

[0066] S1. Weigh 2.5 mmol (0.622 g) of Ni(CH3COO)2·4H2O and 11.2 mmol (89.09 g) of DL-α-alanine into a beaker according to a molar ratio of nickel acetate tetrahydrate to DL-α-alanine of 1:4.5. Add 10 mL of deionized water and stir at 750 rpm for 10 min. Add 140 mL of anhydrous ethanol and continue stirring at 750 rpm for 5 min to form a blue suspension. Centrifuge and wash the solid twice with deionized water and twice with ethanol. Collect the sediment and dry it overnight in air at 60 °C. After drying, allow it to cool naturally to room temperature. Remove the dried sample and grind it into powder in an agate mortar for 15 min. Place the powder in a quartz boat and then place it in a tube furnace at a flow rate of 200 mL / min. -1 In air atmosphere, at 1℃·min -1 The temperature is rapidly increased to 600℃, held at that temperature for 2 hours, and then allowed to cool naturally to obtain a nickel oxide material, denoted as NiO. x powder.

[0067] S2, weigh 0.25 mg NiO according to the ratio of 1 mg: 200 µL: 10 µL. xNiO powder, 50 µL of anhydrous ethanol, and 2.5 µL of Nafion were dispersed in a centrifuge tube by sonication for 0.75 h. The dispersion was then evenly distributed using a pipette onto 0.5 cm × 0.5 cm carbon paper coated with a microporous carbon layer. The mixture was then allowed to dry overnight in air to obtain NiO. x The powder loading was 1.0 mg·cm³. -2 The nickel oxide working electrode, denoted as NiO x Electrode sheet.

[0068] S3 employs a standard three-electrode system, using a carbon rod as the counter electrode, an Hg / HgO electrode as the reference electrode, and NiO... x The electrode plate serves as the working electrode. The working electrode is activated by pulsed potential in a 1M potassium hydroxide solution by sequentially applying a -2V cathode potential short pulse for 1 second, followed by a 2V anode potential short pulse for 1 second, and repeating this process 50 times for NiO. x By introducing surface defects into the electrode sheet, an activated nickel oxide working electrode is obtained.

[0069] S4. A mixed solution containing 1M potassium hydroxide, 40µM Fe(NO3)3·9H2O and 100µM IrCl4·xH2O was prepared as an electrolyte. Electrochemical deposition was performed on the activated nickel oxide working electrode for 10000s at a voltage of 6V to obtain a nickel oxide-based iron-iridium double electrodeposition catalyst.

[0070] Example 5

[0071] A method for preparing a nickel oxide-based iron-iridium dual electrodeposition catalyst includes the following steps:

[0072] S1. Weigh 2.5 mmol (0.622 g) of Ni(CH3COO)2·4H2O and 11.2 mmol (89.09 g) of DL-α-alanine into a beaker according to a molar ratio of nickel acetate tetrahydrate to DL-α-alanine of 1:4.5. Add 10 mL of deionized water and stir at 750 rpm for 10 min. Add 140 mL of anhydrous ethanol and continue stirring at 750 rpm for 5 min to form a blue suspension. Centrifuge and wash the solid twice with deionized water and twice with ethanol. Collect the sediment and dry it overnight in air at 60 °C. After drying, allow it to cool naturally to room temperature. Remove the dried sample and grind it into powder in an agate mortar for 15 min. Place the powder in a quartz boat and then place it in a tube furnace at a flow rate of 200 mL / min. -1 In air atmosphere, at 1℃·min -1 The temperature is rapidly increased to 600℃, held at that temperature for 2 hours, and then allowed to cool naturally to obtain a nickel oxide material, denoted as NiO. x powder.

[0073] S2, weigh 0.25 mg NiO according to the ratio of 1 mg: 200 µL: 10 µL. x NiO powder, 50 µL of anhydrous ethanol, and 2.5 µL of Nafion were dispersed in a centrifuge tube by sonication for 0.75 h. The dispersion was then evenly distributed using a pipette onto 0.5 cm × 0.5 cm carbon paper coated with a microporous carbon layer. The mixture was then allowed to dry overnight in air to obtain NiO. x The powder loading was 1.0 mg·cm³. -2 The nickel oxide working electrode, denoted as NiO x Electrode sheet.

[0074] S3 employs a standard three-electrode system, using a carbon rod as the counter electrode, an Hg / HgO electrode as the reference electrode, and NiO... x The electrode plate serves as the working electrode. The working electrode is activated by pulsed potential in a 1M potassium hydroxide solution by sequentially applying a -2V cathode potential short pulse for 1 second, followed by a 2V anode potential short pulse for 1 second, and repeating this process 50 times for NiO. x By introducing surface defects into the electrode sheet, an activated nickel oxide working electrode is obtained.

[0075] S4. A mixed solution containing 1M potassium hydroxide, 80µM Fe(NO3)3·9H2O and 100µM IrCl4·xH2O was prepared as an electrolyte. Electrochemical deposition was performed on the activated nickel oxide working electrode for 10000s at a voltage of 6V to obtain a nickel oxide-based iron-iridium double electrodeposition catalyst.

[0076] To further illustrate the technical effects of the present invention, a comparative example is also provided, as follows:

[0077] Comparative Example 1

[0078] A method for preparing a nickel oxide catalyst includes the following steps:

[0079] S1. Weigh 2.5 mmol (0.622 g) of Ni(CH3COO)2·4H2O and 11.2 mmol (89.09 g) of DL-α-alanine into a beaker according to a molar ratio of nickel acetate tetrahydrate to DL-α-alanine of 1:4.5. Add 10 mL of deionized water and stir at 750 rpm for 10 min. Add 140 mL of anhydrous ethanol and continue stirring at 750 rpm for 5 min to form a blue suspension. Centrifuge and wash the solid twice with deionized water and twice with ethanol. Collect the sediment and dry it overnight in air at 60 °C. After drying, allow it to cool naturally to room temperature. Remove the dried sample and grind it into powder in an agate mortar for 15 min. Place the powder in a quartz boat and then place it in a tube furnace at a flow rate of 200 mL / min. -1 In air atmosphere, at 1℃·min -1 The temperature is rapidly increased to 600℃, held at that temperature for 2 hours, and then allowed to cool naturally to obtain a nickel oxide material, denoted as NiO. x powder.

[0080] S2, weigh 0.25 mg NiO according to the ratio of 1 mg: 200 µL: 10 µL. x NiO powder, 50 µL of anhydrous ethanol, and 2.5 µL of Nafion were dispersed in a centrifuge tube by sonication for 0.75 h. The dispersion was then evenly distributed using a pipette onto 0.5 cm × 0.5 cm carbon paper coated with a microporous carbon layer. The mixture was then allowed to dry overnight in air to obtain NiO. x The powder loading was 1.0 mg·cm³. -2 The nickel oxide working electrode, denoted as NiO x Electrode sheet, i.e., nickel oxide catalyst.

[0081] Comparative Example 2

[0082] A method for preparing a nickel oxide-based iron electrodeposition catalyst includes the following steps:

[0083] S1. Weigh 2.5 mmol (0.622 g) of Ni(CH3COO)2·4H2O and 11.2 mmol (89.09 g) of DL-α-alanine into a beaker according to a molar ratio of nickel acetate tetrahydrate to DL-α-alanine of 1:4.5. Add 10 mL of deionized water and stir at 750 rpm for 10 min. Add 140 mL of anhydrous ethanol and continue stirring at 750 rpm for 5 min to form a blue suspension. Centrifuge and wash the solid twice with deionized water and twice with ethanol. Collect the sediment and dry it overnight in air at 60 °C. After drying, allow it to cool naturally to room temperature. Remove the dried sample and grind it into powder in an agate mortar for 15 min. Place the powder in a quartz boat and then place it in a tube furnace at a flow rate of 200 mL / min. -1 In air atmosphere, at 1℃·min -1 The temperature is rapidly increased to 600℃, held at that temperature for 2 hours, and then allowed to cool naturally to obtain a nickel oxide material, denoted as NiO. x powder.

[0084] S2, weigh 0.25 mg NiO according to the ratio of 1 mg: 200 µL: 10 µL. x NiO powder, 50 µL of anhydrous ethanol, and 2.5 µL of Nafion were dispersed in a centrifuge tube by sonication for 0.75 h. The dispersion was then evenly distributed using a pipette onto 0.5 cm × 0.5 cm carbon paper coated with a microporous carbon layer. The mixture was then allowed to dry overnight in air to obtain NiO. x The powder loading was 1.0 mg·cm³. -2 The nickel oxide working electrode, denoted as NiO x Electrode sheet.

[0085] S3 employs a standard three-electrode system, using a carbon rod as the counter electrode, an Hg / HgO electrode as the reference electrode, and NiO... x The electrode plate serves as the working electrode. The working electrode is activated by pulsed potential in a 1M potassium hydroxide solution by sequentially applying a -2V cathode potential short pulse for 1 second, followed by a 2V anode potential short pulse for 1 second, and repeating this process 50 times for NiO. x By introducing surface defects into the electrode sheet, an activated nickel oxide working electrode is obtained.

[0086] S4, a mixed solution containing 1M potassium hydroxide and 100µM Fe(NO3)3·9H2O was prepared as the electrolyte. Electrochemical deposition was performed on the activated nickel oxide working electrode at 6V for 10000s to obtain a nickel oxide-based iron electrodeposition catalyst, denoted as NiO. x -Fe.

[0087] Comparative Example 3

[0088] A method for preparing a nickel oxide-based iridium electrodeposition catalyst includes the following steps:

[0089] S1. Weigh 2.5 mmol (0.622 g) of Ni(CH3COO)2·4H2O and 11.2 mmol (89.09 g) of DL-α-alanine into a beaker according to a molar ratio of nickel acetate tetrahydrate to DL-α-alanine of 1:4.5. Add 10 mL of deionized water and stir at 750 rpm for 10 min. Add 140 mL of anhydrous ethanol and continue stirring at 750 rpm for 5 min to form a blue suspension. Centrifuge and wash the solid twice with deionized water and twice with ethanol. Collect the sediment and dry it overnight in air at 60 °C. After drying, allow it to cool naturally to room temperature. Remove the dried sample and grind it into powder in an agate mortar for 15 min. Place the powder in a quartz boat and then place it in a tube furnace at a flow rate of 200 mL / min. -1 In air atmosphere, at 1℃·min -1 The temperature is rapidly increased to 600℃, held at that temperature for 2 hours, and then allowed to cool naturally to obtain a nickel oxide material, denoted as NiO. x powder.

[0090] S2, weigh 0.25 mg NiO according to the ratio of 1 mg: 200 µL: 10 µL. x NiO powder, 50 µL of anhydrous ethanol, and 2.5 µL of Nafion were dispersed in a centrifuge tube by sonication for 0.75 h. The dispersion was then evenly distributed using a pipette onto 0.5 cm × 0.5 cm carbon paper coated with a microporous carbon layer. The mixture was then allowed to dry overnight in air to obtain NiO. x The powder loading was 1.0 mg·cm³. -2 The nickel oxide working electrode, denoted as NiO x Electrode sheet.

[0091] S3 employs a standard three-electrode system, using a carbon rod as the counter electrode, an Hg / HgO electrode as the reference electrode, and NiO... x The electrode plate serves as the working electrode. The working electrode is activated by pulsed potential in a 1M potassium hydroxide solution by sequentially applying a -2V cathode potential short pulse for 1 second, followed by a 2V anode potential short pulse for 1 second, and repeating this process 50 times for NiO. x By introducing surface defects into the electrode sheet, an activated nickel oxide working electrode is obtained.

[0092] S4, a mixed solution containing 1M potassium hydroxide and 100µM IrCl4·xH2O was prepared as the electrolyte. Electrochemical deposition was performed on the activated nickel oxide working electrode at 6V for 10000s to obtain a nickel oxide-based iridium electrodeposition catalyst, denoted as NiO.x -Ir.

[0093] The performance of the catalysts prepared in the above embodiments and comparative examples was tested, and the results are as follows.

[0094] Figure 1 The images show aberration-corrected high-angle annular dark-field scanning transmission electron microscope (STEM) images of the nickel oxide-based iron-iridium dual electrodeposition catalyst prepared in Example 1 of this invention. As shown in Figures (a) and (b), Fe and Ir are uniformly distributed in NiO in the form of nanoclusters and a small number of single atoms. x An iron oxide film was grown on the substrate and on the outer side of the substrate. Figure 1 Figures (c) to (e) visually illustrate the effects of Ir, O, and Ni elements on NiO. x Uniformly distributed on the substrate, the multi-scale site distribution on the surface increases the active surface area of ​​the catalyst, allowing more reactants to contact the active sites and thus improving catalytic efficiency. Furthermore, the coexistence of single atoms and nanoclusters produces a synergistic effect, further enhancing catalytic performance. NiO x The substrate provides stable support for the metal sites, while the introduction of the metal sites also alters the NiO content. x The surface electronic structure enhances catalytic performance.

[0095] Figure 2 Linear sweep voltammetry curves of the catalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 3 of this invention for the OER reaction. Figure 3 The catalysts prepared for Examples 1-2 and Comparative Examples 1-3 of this invention were subjected to an ampere reaction at 10 mA·cm⁻¹. -2 The overpotential required for the OER reaction in the electrocatalytic splitting of water. Figure 2 and Figure 3 As shown, NiO x An overpotential of 320mV is required to reach 10mA·cm. -2 The current density was [not specified]. However, after introducing Ir single atoms, the overpotential decreased significantly, to 197 mV and 254 mV, respectively. [The last part, "NiO," appears to be incomplete and possibly refers to a different topic. It likely refers to a different topic.] x -IrFe 0.2 and NiO x The overpotentials of -IrFe are 198 mV and 201 mV, respectively, compared with NiO. x The Ir content is similar. This indicates that the synergistic introduction of Fe and Ir significantly reduces the potential required for the OER reaction, and Example 2 maintains high efficiency even at low iron precursor concentrations, confirming the dual advantages of this catalyst system in terms of stability and catalytic efficiency. NiO x - The overpotential of Fe reached 254 mV, higher than that of Examples 1 and 2 of bimetallic co-deposition, highlighting the insufficient activity of Fe electrodeposition alone in the OER reaction; NiOx The Ir overpotential is 197 mV, which is comparable to the performance of the example. However, from a cost-effectiveness perspective, the pure Ir electrodeposition catalyst is significantly inferior to the Fe and Ir co-deposition system. Looking at the overall trend of the curves, the catalyst in the example shows a significantly lower onset potential, meaning it can trigger the OER reaction at a lower potential. In the high potential range, the current density rises rapidly, exhibiting strong reaction kinetics. In contrast, the pure NiO... x The catalyst exhibits a slow increase in current density at high potentials, reflecting its poor reaction kinetics.

[0096] Figure 4 This is a Tafel slope diagram of the OER reaction in the electrocatalytic water splitting of the catalysts prepared in Examples 1-2 and Comparative Examples 1-3 of this invention. Figure 4 It can be seen that pure NiO x The Tafel slope of the catalyst is 78.96 mV·dec. -1 NiO deposited by a single metal x -Ir、NiO x The Tafel slopes for -Fe are 57.46 mV·dec. -1 and 72.08mV·dec -1 Compared to pure NiO x The decrease indicates that the introduction of Ir or Fe improved the reaction kinetics to some extent. Further examination reveals that the bimetallic deposited NiO... x -IrFe 0.2 and NiO x -IrFe has a lower Tafel slope, at 53.06 mV·dec. -1 and 51.37mV·dec -1 Significantly lower than single-metal modified and pure NiO x Catalyst. This indicates that the synergistic deposition of Ir and Fe, compared to single-metal deposition, is more effective in reducing reaction kinetics and accelerating the charge transfer process. Among them, NiO... x -IrFe exhibits the smallest Tafel slope, meaning it has optimal reaction kinetics in the oxygen evolution reaction and can promote the reaction at a faster rate.

[0097] Figure 5 Electrochemically active surface area diagrams obtained by cyclic voltammetry for the OER reaction of water electrocatalytic splitting using catalysts prepared in Examples 1-2 and Comparative Examples 1-3 of this invention. Figure 5 It can be seen that in bimetallic deposition catalysts, NiO x -IrFe 0.2 and NiO x -IrFe C a The values ​​were 41.00 mF·cm.-2 and 28.16 mF·cm -2 Although lower than NiO x -Ir, but still much higher than pure NiO. x With NiO x -Fe, confirming that co-deposition of Fe and Ir can effectively increase the number of active sites. A larger ECSA indicates that more active sites, such as Ni, are exposed on the catalyst surface. 3+ Oxygen vacancies and other features provide ample catalytic active sites for the OER reaction. Simultaneously, the high electrochemical active surface area corresponds to a large double-layer capacitance, reflecting excellent interfacial charge storage and transfer efficiency, which accelerates the kinetics of *OH adsorption and OO bond formation, thereby enhancing the activity and stability of the catalytic reaction.

[0098] Figure 6 The catalysts prepared for Examples 1-2 and Comparative Examples 1-3 of this invention were subjected to an ampere reaction at 10 mA·cm⁻¹. -2 Stability test graphs for the OER reaction in electrocatalytic water splitting are shown, assessed by measuring the time required for a 100 mV increase in potential. Figure 6 It can be seen that pure NiO x It only takes 50 hours for the potential of NiO to rise by 100mV. x -IrFe 0.2 and NiO x -IrFe requires 232 h and 261 h respectively to increase its potential by 100 mV, especially NiO. x -IrFe is more stable than pure NiO x The more than five-fold increase highlights the crucial role of the synergistic effect of the iron-iridium dual-site deposition in suppressing catalyst degradation. This result demonstrates that the iron-iridium dual-deposition catalyst can maintain high catalytic performance over long periods of operation, making it suitable for continuous operation in practical applications. Excellent stability also indicates that the catalyst possesses good resistance to corrosion and poisoning, remaining stable in complex electrolyte environments.

[0099] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a nickel oxide-based iron-iridium dual electrodeposition catalyst, characterized in that, Includes the following steps: Using DL-α-alanine as a ligand, with Ni 2+ The source forms a Ni-alanine complex, which is then pyrolyzed at 550℃~620℃ in air to decompose the complex in the Ni-alanine complex and obtain nickel oxide material. The nickel oxide material was prepared as a nickel oxide working electrode, using an iron precursor, an iridium precursor, and OH. - The mixed solution of the source is used as the electrolyte. Through electrochemical deposition, iron-iridium bimetal is deposited on the nickel oxide working electrode to obtain a nickel oxide-based iron-iridium bimetallic electrodeposition catalyst. In the electrolyte, the molar ratio of iridium precursor to iron precursor is 1:0.2~2; Prior to electrochemical deposition, the nickel oxide working electrode is electrochemically activated, specifically by using a standard three-electrode electrode to deposit OH- ions. － In the solution, short pulses of cathode potential of 0.5s~1.5s and -2V~-1.5V and short pulses of anode potential of 0.5s~1.5s and 1.5V~2V are sequentially applied to the nickel oxide working electrode. The electrochemical deposition was performed using a chronoamperometry method with a voltage of 5V~7V and a deposition time of 8000s~12000s.

2. The preparation method of the nickel oxide-based iron-iridium dual electrodeposition catalyst according to claim 1, characterized in that, In the electrolyte, the molar ratio of iridium precursor to iron precursor is 1:

1.

3. The preparation method of the nickel oxide-based iron-iridium dual electrodeposition catalyst according to claim 1, characterized in that, One cycle consists of one short pulse at the cathode potential and one short pulse at the anode potential, and the cycle is repeated 40 to 60 times.

4. The method for preparing the nickel oxide-based iron-iridium dual electrodeposition catalyst according to claim 1, characterized in that, The nickel oxide working electrode is prepared by ultrasonically mixing the nickel oxide material, ethanol, and Nafion, and then drop-coating the mixture onto carbon paper to obtain a nickel oxide material loading of 0.8 mg / cm³. 2 ~2.3mg / cm 2 Nickel oxide working electrode.

5. The method for preparing the nickel oxide-based iron-iridium dual electrodeposition catalyst according to claim 1, characterized in that, The Ni 2+ The molar ratio of the source to DL-α-alanine is 1:4~5.

6. The method for preparing the nickel oxide-based iron-iridium dual electrodeposition catalyst according to claim 1, characterized in that, The pyrolysis time is 1.5h to 3h.

7. A nickel oxide-based iron-iridium dual electrodeposition catalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the nickel oxide-based iron-iridium double electrodeposition catalyst according to claim 7 in catalytic water electrolysis.

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