Ir-loaded nickel-vanadium nitride as well as preparation method and application thereof

Abstract

The invention relates to an Ir-loaded nickel-vanadium nitride and a preparation method and application thereof, the Ir-loaded nickel-vanadium nitride comprises a vanadium modified Ni3N carrier and precious metal Ir loaded on the vanadium modified Ni3N carrier, and the Ir-loaded nickel-vanadium nitride is of a multi-composite structure on the whole. The preparation method of the Ir-loaded nickel-vanadium nitride comprises the steps of hydrothermal reaction, plasma activation treatment, Ir loading, ammoniation and the like. The preparation method comprises the following steps: firstly, modifying a Ni3N carrier, optimizing an electronic structure of Ni3N by utilizing a vanadium element, and improving the adsorption and cracking capability of the Ni3N to water molecules, so that the Ni3N carrier becomes an excellent hydrogen evolution catalyst; then, the hydrogen evolution activity of the catalyst is further improved by loading low-content noble metal Ir on the modified Ni3N carrier; the prepared low-load Ir nickel-vanadium nitride is an alkaline hydrogen evolution catalyst with high catalytic activity, and can reduce hydrogen production energy consumption and cost when being applied to the field of hydrogen production by water electrolysis.

Description

Technical Field

[0001] The present invention relates to the field of electrolyzed water catalysis, and in particular to a nickel vanadium nitride loaded with Ir, a preparation method thereof, and an application thereof. Background Art

[0002] Hydrogen is an important secondary energy source and chemical raw material. However, at present, most industrial hydrogen is still prepared by cracking fossil fuels. In addition, hydrogen production by electrolyzing water can obtain clean hydrogen energy. However, the electrochemical hydrogen production represented by water electrolysis has a yield of less than 4%. High energy consumption and high cost are the main reasons hindering the vigorous development of hydrogen production by electrolyzing water.

[0003] In the hydrogen production by electrolyzing water, the assistance of an electrocatalyst can accelerate the cathodic hydrogen evolution reaction and the anodic oxygen evolution reaction during water electrolysis, thereby reducing the energy consumption of hydrogen production by electrolyzing water. At present, the most efficient hydrogen evolution catalyst is still the Pt-based material. Due to the non-negligible dependence of large-scale hydrogen production by electrolyzing water on noble metal catalysts (such as high-loading Ru, Ir, and Pt-based catalysts), the use of noble metal catalysts has sharply increased the cost of hydrogen production by electrolyzing water.

[0004] The Pt-based catalyst is theoretically the most excellent hydrogen evolution catalyst because it has excellent adsorption performance with the intermediate H* (i.e., active hydrogen), and the Gibbs adsorption free energy is almost close to 0. However, this adsorption performance of the Pt-based catalyst with the intermediate H* can only be observed in the acidic hydrogen evolution system. In the alkaline hydrogen evolution system, since the protons or water and protons participating in the hydrogen evolution reaction are not as extensive as in the acidic system, it is necessary to first realize the adsorption, splitting, and hydroxyl transfer of water molecules on the surface of the Pt-based catalyst to obtain protons. However, in the alkaline hydrogen evolution system, the adsorption of Pt on water molecules and hydroxyls is too strong, so that the active sites are occupied, and it is difficult to realize the subsequent proton transfer process. Therefore, the adsorption performance of the Pt-based catalyst for active hydrogen in the alkaline hydrogen evolution system is often not as good as that in the acidic hydrogen evolution system. Therefore, it is necessary to further improve the hydrophilicity of the Pt-based catalyst in the alkaline hydrogen evolution system and its adsorption energy with the intermediate H*. Summary of the Invention

[0005] In view of this, the present invention provides a nickel vanadium nitride loaded with Ir, a preparation method thereof, and an application thereof. By modifying the Ni3N support and then loading a low content of noble metal Ir thereon, a highly catalytically active alkaline hydrogen evolution catalyst is obtained, which is applied in the field of hydrogen production by electrolyzing water to reduce the hydrogen production energy consumption and cost.

[0006] Specifically, the present invention is realized by the following technical solutions:

[0007] According to a first aspect of the present invention, there is provided an Ir-loaded nickel vanadium nitride, which comprises a vanadium-modified Ni3N support and a noble metal Ir supported on the vanadium-modified Ni3N support.

[0008] In the above-mentioned Ir-loaded nickel vanadium nitride, the Ir-loaded nickel vanadium nitride as a whole presents a multiple composite structure. The Ir-loaded nickel vanadium nitride is a nanosheet composed of particles with a size of 20-50 nm, and the diameter of the nanosheet is 500-1000 nm. Among them, the nanoparticles are caused by the structural transformation of the product before and after ammoniation, that is, from NiV double metal hydroxide to NiV oxynitride.

[0009] In the above-mentioned Ir-loaded nickel vanadium nitride, as an alternative embodiment, the Ir-loaded nickel vanadium nitride comprises elements Ni, V, Ir, O and N. Among them, without considering the nickel foam substrate, the mass loading of Ir accounts for about 2-10% of the mass of the Ir-loaded nickel vanadium nitride, and the molar ratio of Ni to V elements is about 2-4:1, and the molar ratio of Ni to N is about 3:1.

[0010] In the above-mentioned Ir-loaded nickel vanadium nitride, the molar ratio of V element to O element is 1:1.60-1.62.

[0011] The present invention first modifies the Ni3N support, uses vanadium element to optimize the electronic structure of Ni3N, improves its ability to adsorb and crack water molecules, and makes it an excellent hydrogen evolution catalyst. Then, by loading a low content of noble metal Ir on the modified Ni3N support, the hydrogen evolution activity of the catalyst is further improved. Specifically, in the Ir-loaded nickel vanadium nitride according to the present invention, the V element exists in the form of VO x compound, and by forming a composite heterostructure with Ni3N, the surface electronic structure is changed, so that the bonding of the O element in the water molecule is enhanced, and the water adsorption and cracking kinetics of the original catalyst can be improved.

[0012] For Ir, although its adsorption energy with the intermediate H* is not as ideal as that of Pt, it has advantages in the adsorption and cracking of water molecules in alkaline electrolyte. In addition, Ir can further improve the adsorption energy of the intermediate H* by interacting with the Ni3N support. Thereby improving the hydrophilicity of the Ni3N support and the adsorption energy of the remaining intermediate H*, and obtaining an Ir-loaded nickel vanadium nitride with excellent electrical conductivity and corrosion resistance.

[0013] For the Ir-loaded nickel vanadium nitride according to the present invention, by adopting the preparation process of a nitride-based three-dimensional electrode with a low noble metal Ir loading, it is expected to reduce the hydrogen production cost.

[0014] According to a second aspect of the present invention, there is provided a method for preparing the above-mentioned Ir-loaded nickel vanadium nitride, and the preparation method includes the following steps:

[0015] 1) Dissolve nickel salt, vanadium salt and urea in water, stir evenly to obtain a vanadium-nickel mixed solution;

[0016] 2) Immerse the foam metal substrate in the vanadium-nickel mixed solution for hydrothermal reaction to obtain a foam metal substrate loaded with NiV double metal hydroxide, that is, a NiV-modified foam metal substrate (that is, grow NiV double metal hydroxide on the foam metal substrate);

[0017] 3) Place the NiV-modified foam metal substrate in a plasma generator, and perform plasma activation treatment on it with Ar gas to obtain a plasma-activated NiV-modified foam metal substrate, so as to generate more vacancies and defects on the surface of the NiV double metal hydroxide for loading single atom clusters;

[0018] 4) Immerse the plasma-activated NiV-modified foam metal substrate with an Ir salt solution to obtain an Ir-loaded NiV-modified foam metal substrate;

[0019] 5) Calcinate the Ir-loaded NiV-modified foam metal substrate at a high temperature in the presence of a reaction gas for ammoniation treatment to obtain the above-mentioned Ir-loaded nickel vanadium nitride, wherein the reaction gas is ammonia gas.

[0020] In the above-mentioned method for preparing the Ir-loaded nickel vanadium nitride, the preparation method further includes pretreatment of the foam metal substrate.

[0021] In the above-mentioned method for preparing the Ir-loaded nickel vanadium nitride, the steps of the pretreatment of the foam metal substrate include: washing the foam metal substrate to obtain a substrate with a clean surface.

[0022] In the above-mentioned method for preparing the Ir-loaded nickel vanadium nitride, the foam metal substrate includes any one of foam nickel, foam nickel cobalt, foam cobalt, foam iron, foam nickel iron, nickel mesh and stainless steel mesh.

[0023] In the above-mentioned method for preparing the Ir-loaded nickel vanadium nitride, the pretreatment of the foam metal substrate includes: cutting a certain size of foam metal, and alternately washing the substrate with water, ethanol, acetone, water, dilute hydrochloric acid (for example, 3 mol / L hydrochloric acid), and water, and set aside after washing.

[0024] In the present invention, the foam metal substrate is pretreated to remove dust, oil and surface oxides on the surface, so as to obtain a foam metal substrate with a clean surface, which is beneficial to loading NiV double metal hydroxide on the surface of the foam metal substrate during the subsequent hydrothermal reaction process.

[0025] In the preparation method of the above-mentioned Ir-loaded nickel vanadium nitride, the foam metal substrate is ultrasonically washed.

[0026] In the preparation method of the above-mentioned Ir-loaded nickel vanadium nitride, after ultrasonically washing the foam metal substrate, it does not need to be dried.

[0027] In the preparation method of the above-mentioned Ir-loaded nickel vanadium nitride, in the step 1), the total concentration of nickel salt and vanadium salt is 35-50 mmol / L according to Ni 2+ and V 3+ .

[0028] In the preparation method of the above-mentioned Ir-loaded nickel vanadium nitride, in the step 1), the molar ratio of nickel salt and vanadium salt is 2:1-4:1 according to Ni 2+ and V 3+ .

[0029] In the preparation method of the above-mentioned Ir-loaded nickel vanadium nitride, in the step 1), the concentration of urea is 60-80 mmol / L.

[0030] In the preparation method of the above-mentioned Ir-loaded nickel vanadium nitride, in the step 1), the nickel salt includes nickel chloride (such as NiCl2·H2O); the vanadium salt includes VCl3.

[0031] In the preparation method of the above-mentioned Ir-loaded nickel vanadium nitride, in the step 2), the reaction temperature of the hydrothermal reaction is 120-140 °C, and the reaction time is 12-24 hours.

[0032] In the preparation method of the above-mentioned Ir-loaded nickel vanadium nitride, the hydrothermal reaction also includes taking out the product generated after the hydrothermal reaction, washing it with water, absolute ethanol and acetone successively for multiple times, and vacuum drying; preferably, the vacuum drying temperature is 50 °C.

[0033] In the preparation method of the above-mentioned Ir-loaded nickel vanadium nitride, in the step 2), the hydrothermal reaction is carried out in a reaction kettle.

[0034] In the preparation method of the above-mentioned Ir-loaded nickel vanadium nitride, in the step 2), after the hydrothermal reaction, the nickel foam needs to be taken out, washed and vacuum dried, preferably vacuum dried at 50 °C.

[0035] In the preparation method of the above-mentioned Ir-loaded nickel vanadium nitride, in the step 3), the plasma power is 50-100 W, and the activation time is 5-15 minutes.

[0036] By controlling the power and time of plasma treatment, the present invention controls the concentration of oxygen defects generated on the surface of nickel vanadium oxide, thereby further controlling the Ir loading amount on the surface of the metal foam substrate. Therefore, by reasonably controlling the plasma power and time, it is beneficial to improve the Ir loading effect on the surface of the metal foam substrate.

[0037] In the method for preparing the Ir-loaded nickel vanadium nitride described above, in step 4), the impregnation solution is an ethanol solution of IrCl3, wherein the concentration of IrCl3 is 0.5 - 5 mmol / L.

[0038] The present invention uses an ethanol solution of IrCl3, which is beneficial to improving the solubility of IrCl3 in the solution, thereby facilitating the control of the IrCl3 loading amount on the surface of the metal foam substrate. By increasing the solubility of IrCl3, a small amount of IrCl3 can be used to achieve a high Ir loading amount on the surface of the metal foam substrate, thus reducing the usage amount of the precious metal Ir, avoiding the waste of precious metal Ir raw materials, and further reducing the production cost of the Ir-loaded nickel vanadium nitride.

[0039] In the method for preparing the Ir-loaded nickel vanadium nitride described above, in step 5), the calcination temperature is 300 - 400 °C, the calcination time is 2 - 5 hours, and the heating rate is 5 - 10 °C / minute.

[0040] In the present invention, by controlling the calcination temperature, on the one hand, nickel vanadium hydroxide is converted into a Ni3N and VO x composite structure, and on the other hand, the interaction force between the loaded Ir 3+ and the metal foam substrate is enhanced.

[0041] In the method for preparing the Ir-loaded nickel vanadium nitride described above, step 5) further includes washing and vacuum drying the ammoniated product.

[0042] In the method for preparing the Ir-loaded nickel vanadium nitride described above, step 5) further includes washing and vacuum drying the ammoniated product at a temperature of 50 °C.

[0043] The present invention first uses a hydrothermal synthesis process to grow NiV double metal hydroxide on the metal foam substrate, and then uses Ar plasma to treat the NiV double metal hydroxide to generate more vacancies and defects on its surface (specifically, Ar plasma can extract some oxygen atoms from the material surface to generate oxygen vacancies) for loading single atom clusters; further, the treated overall electrode is immersed in a solution of Ir to load Ir clusters; finally, the electrode sheet is placed in a tubular furnace filled with ammonia gas for calcination to convert the NiV double metal hydroxide substrate into nickel vanadium nitride oxide, and at the same time, the binding force between the loaded Ir clusters and the substrate is enhanced.

[0044] According to the third aspect of the present invention, there is provided an application of the above-mentioned Ir-loaded nickel vanadium nitride as a catalyst or electrode for hydrogen evolution at the cathode in alkaline water electrolysis for hydrogen production.

[0045] In the above application, when the Ir-loaded NiV nitride is used as a catalyst or electrode for hydrogen evolution at the cathode in alkaline water electrolysis for hydrogen production, the overpotential of the hydrogen evolution reaction can be reduced to 14 mV at a current density of 10 mA / cm 2 ².

[0046] In the present invention, the skeleton of the foam metal substrate (for example, nickel foam) is a three-dimensional ordered skeleton, which itself has a macroporous structure. The catalyst loaded on its surface is Ir-containing nickel vanadium nitride nanoparticles, which belong to microporous-mesoporous materials and are arranged in an orderly manner. Therefore, the Ir-loaded nickel vanadium nitride according to the present invention can directly synthesize a three-dimensional ordered structure electrode, avoiding the use of adhesives.

[0047] When the Ir-loaded nickel vanadium nitride according to the present invention is used for alkaline water electrolysis for hydrogen production, it can optimize the adsorption and dissociation of water molecules, improve the adsorption of H* intermediates, reduce the energy barrier, and thus improve the hydrogen evolution effect of the hydrogen evolution reaction at the cathode.

[0048] In the present invention, without conflict, the above technical features can be freely combined to form a new technical solution.

[0049] The above technical solution provided by the embodiment of the present invention has the following advantages compared with the prior art:

[0050] (1) According to the technical solution of the present invention, by modifying the Ni₃N support, a low content of precious metal Ir is loaded on the modified Ni₃N support. The obtained Ir-loaded nickel vanadium nitride as an alkaline hydrogen evolution catalyst has high catalytic activity although the loading amount of precious metal Ir is low, and can reduce the hydrogen production energy consumption and cost when applied in the field of water electrolysis for hydrogen production. That is, according to the technical solution of the present invention, ultra-low loading of Ir can be achieved, and the activity of the obtained alkaline hydrogen evolution catalyst exceeds that of the commercial Pt / C catalyst, thereby realizing cost control of the alkaline hydrogen evolution catalyst;

[0051] (2) VO in the support of the Ir-loaded nickel vanadium nitride according to the present invention x can enhance the hydrophilic property of Ni₃N and enhance the overall water adsorption and dissociation kinetics of the catalyst;

[0052] (3) The Ir-loaded nickel vanadium nitride according to the present invention belongs to microporous-mesoporous materials and is arranged in an orderly manner. This material can directly synthesize a three-dimensional ordered structure electrode, avoiding the use of adhesives. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The accompanying drawings here are incorporated into the specification and form a part of this specification, showing embodiments in accordance with the present invention, and are used together with the specification to explain the principles of the present invention.

[0054] Figure 1 It is a scanning electron microscope (SEM) image of the Ir-loaded NiV oxynitride electrode prepared in Preparation Example 1 of the present invention;

[0055] Figure 2 It is an EDS image of the Ir-loaded NiV oxynitride electrode prepared in Preparation Example 1 of the present invention;

[0056] Figure 3 It is an SEM image of the NiV double metal hydroxide in Preparation Example 1 of the present invention;

[0057] Figure 4 It is a hydrogen evolution polarization curve of the Ir-loaded NiV oxynitride electrode prepared in Preparation Example 1 of the present invention and a commercial noble metal catalyst in 1.0 mol / L KOH (using Ni foam as the substrate with internal resistance compensation). Detailed Embodiments

[0058] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0059] According to some embodiments of the first aspect of the present invention, there is provided an Ir-loaded nickel vanadium nitride, wherein the Ir-loaded nickel vanadium nitride includes a vanadium-modified Ni3N support and a noble metal Ir supported on the vanadium-modified Ni3N support.

[0060] According to some embodiments of the first aspect of the present invention, the Ir-loaded nickel vanadium nitride as a whole presents a multiple composite structure. The Ir-loaded nickel vanadium nitride is a nanosheet composed of particles with a size of 20 - 50 nm, and the diameter of the nanosheet is 500 - 1000 nm; wherein, the nanoparticles are caused by the structural transformation of the product before and after ammoniation, that is, from NiV double metal hydroxide to NiV oxynitride.

[0061] According to some embodiments of the first aspect of the present invention, as an alternative implementation, the Ir-loaded nickel vanadium nitride comprises Ni, V, Ir, O and N elements. Among them, without considering the nickel foam substrate, the mass loading of Ir accounts for about 2-10% of the mass of the Ir-loaded nickel vanadium nitride (for example, 3%, 5%, 7%, 8% or 9%), and the molar ratio of Ni to V elements is about 2-4:1 (for example, 2.5:1, 2.8:1, 3:1 or 3.5:1).

[0062] According to some embodiments of the first aspect of the present invention, the molar ratio of V element to O element is 1:1.60-1.62 (for example, 1:1.61).

[0063] According to some embodiments of the second aspect of the present invention, a method for preparing Ir-loaded nickel vanadium nitride is provided. The preparation method comprises the following steps:

[0064] 1) Dissolve nickel salt, vanadium salt and urea in water, stir evenly to obtain a vanadium-nickel mixed solution;

[0065] 2) Immerse the foam metal substrate in the vanadium-nickel mixed solution for hydrothermal reaction to obtain a foam metal substrate loaded with NiV double metal hydroxide, that is, a NiV-modified foam metal substrate (that is, grow NiV double metal hydroxide on the foam metal substrate);

[0066] 3) Place the NiV-modified foam metal substrate in a plasma generator, and perform plasma activation treatment on it with Ar gas to obtain a plasma-activated NiV-modified foam metal substrate, so as to generate more vacancies and defects on the surface of the NiV double metal hydroxide for loading single atom clusters;

[0067] 4) Impregnate the plasma-activated NiV-modified foam metal substrate with an Ir salt solution to obtain an Ir-loaded NiV-modified foam metal substrate;

[0068] 5) Calcinate the Ir-loaded NiV-modified foam metal substrate at high temperature in the presence of a reaction gas for ammoniation treatment to obtain the Ir-loaded nickel vanadium nitride, wherein the reaction gas is ammonia gas.

[0069] According to some embodiments of the second aspect of the present invention, the preparation method further comprises the pretreatment of the foam metal substrate.

[0070] According to some embodiments of the second aspect of the present invention, the steps of the pretreatment of the foam metal substrate include: washing the foam metal substrate to obtain a substrate with a clean surface.

[0071] According to some embodiments of the second aspect of the present invention, the foam metal substrate includes any one of nickel foam, nickel-cobalt foam, cobalt foam, iron foam, nickel-iron foam, nickel mesh, and stainless steel mesh.

[0072] According to some embodiments of the second aspect of the present invention, in the step 1), the nickel salt and the vanadium salt are in a total concentration of Ni 2+ and V 3 + of 35 to 50 mmol / L (for example, 40 mmol / L, 45 mmol / L, or 48 mmol / L).

[0073] According to some embodiments of the second aspect of the present invention, in the step 1), the nickel salt and the vanadium salt are in a molar ratio of Ni 2+ and V 3 + of 2:1 to 4:1 (for example, 2:1, 2.2:1, 2.5:1, 3:1, 3.5:1, or 3.8:1).

[0074] According to some embodiments of the second aspect of the present invention, in the step 1), the urea concentration is 60 to 80 mmol / L (for example, 62 mmol / L, 65 mmol / L, 70 mmol / L, 75 mmol / L, or 78 mmol / L).

[0075] In the above method for preparing the Ir-loaded nickel vanadium nitride, in the step 1), the nickel salt includes nickel chloride (such as NiCl2·H2O); the vanadium salt includes VCl3.

[0076] According to some embodiments of the second aspect of the present invention, in the step 2), the reaction temperature of the hydrothermal reaction is 120 to 140 °C (for example, 120 °C, 130 °C, or 140 °C), and the reaction time is 12 to 24 hours (for example, 13 hours, 15 hours, 18 hours, 20 hours, or 22 hours).

[0077] According to some embodiments of the second aspect of the present invention, the hydrothermal reaction further includes taking out the product generated after the hydrothermal reaction, washing it with water, absolute ethanol, and acetone successively for multiple times, and drying it under vacuum; preferably, the vacuum drying temperature is 50 °C.

[0078] According to some embodiments of the second aspect of the present invention, in the step 2), the hydrothermal reaction is carried out in a reaction kettle.

[0079] According to some embodiments of the second aspect of the present invention, in the step 2), after the hydrothermal reaction, the nickel foam needs to be taken out, washed, and dried under vacuum, preferably dried under vacuum at 50 °C.

[0080] According to some embodiments of the second aspect of the present invention, in step 3), the plasma power is 50-100 W (for example, 60 W, 70 W, 80 W or 90 W), and the activation time is 5-15 minutes (for example, 7 minutes, 10 minutes or 13 minutes).

[0081] By controlling the power and time of plasma treatment, the present invention controls the concentration of oxygen defects generated on the surface of nickel vanadium oxide, thereby further controlling the Ir loading amount on the surface of the foam metal substrate. Therefore, by reasonably controlling the plasma power and time, it is beneficial to improve the Ir loading effect on the surface of the foam metal substrate.

[0082] According to some embodiments of the second aspect of the present invention, in step 4), the impregnation solution is an ethanol solution of IrCl3, wherein the concentration of IrCl3 is 0.5-5 mmol / L (1 mmol / L, 1.5 mmol / L, 2 mmol / L, 3 mmol / L, 4 mmol / L or 4.5 mmol / L).

[0083] The present invention uses an ethanol solution of IrCl3, which is beneficial to improving the solubility of IrCl3 in the solution, thereby facilitating the control of the IrCl3 loading amount on the surface of the foam metal substrate. By increasing the solubility of IrCl3, a small amount of IrCl3 can be used to achieve a high Ir loading amount on the surface of the foam metal substrate, thereby reducing the usage amount of the precious metal Ir, avoiding the waste of precious metal Ir raw materials, and further reducing the production cost of the Ir-loaded nickel vanadium nitride.

[0084] According to some embodiments of the second aspect of the present invention, in step 5), the calcination temperature is 300-400 °C (for example, 300 °C, 350 °C, 380 °C or 400 °C), the calcination time is 2-5 hours (for example, 2.5 h, 3 h, 4 h or 4.5 h), and the heating rate is 5-10 °C / minute (for example, 8 °C / minute or 10 °C / minute).

[0085] In the present invention, by controlling the calcination temperature, on the one hand, nickel vanadium hydroxide is converted into a Ni3N and VO x composite structure, and on the other hand, the interaction force between the loaded Ir 3+ and the foam metal substrate is enhanced.

[0086] According to some embodiments of the second aspect of the present invention, step 5) further includes washing and vacuum drying the ammoniated product.

[0087] According to some embodiments of the second aspect of the present invention, a method for preparing an Ir-loaded nickel vanadium nitride is provided, and the preparation method includes the following steps:

[0088] S1) The foam metal substrate is ultrasonically washed alternately with water, ethanol, acetone, water, 3 mol / L dilute hydrochloric acid, and water for 5 minutes without drying.

[0089] S2) Nickel salts (e.g., NiCl6·H2O), vanadium salts (e.g., VCl3), and urea are dissolved in water and stirred evenly to obtain a vanadium-nickel mixed solution. Among them, the total concentration of Ni 2+ and V 3+ is 35 - 50 mmol / L, the molar ratio of Ni 2+ and V 3+ is between 2:1 and 4:1, and the urea concentration is between 60 - 80 mmol / L.

[0090] S3) The foam metal substrate is immersed in the vanadium-nickel mixed solution and subjected to hydrothermal reaction in a reaction kettle to obtain a foam metal substrate loaded with NiV double metal hydroxide, that is, a NiV-modified foam metal substrate (i.e., growing NiV double metal hydroxide on the foam metal substrate). Among them, the reaction temperature is 120 - 140 °C, and the reaction time is 12 - 24 hours.

[0091] S4) The NiV-modified foam metal substrate is placed in a plasma generator and subjected to plasma activation treatment with Ar gas to obtain a plasma-activated NiV-modified foam metal substrate, making more vacancies and defects generated on the surface of the NiV double metal hydroxide for loading single-atom clusters. Among them, the power is 50 - 100 W, and the activation time is 5 - 15 minutes.

[0092] S5) The plasma-activated NiV-modified foam metal substrate is impregnated with an Ir salt solution (e.g., an ethanol solution of IrCl3) to obtain an Ir-loaded NiV-modified foam metal substrate. The concentration of the ethanol solution of IrCl3 is 0.5 - 5 mmol / L.

[0093] S6) Using ammonia gas as the reaction gas, the Ir-loaded NiV-modified foam metal substrate is calcined at high temperature to obtain the loaded Ir nickel vanadium nitride. The calcination temperature is 300 - 400 °C, the time is 3 hours, and the heating rate is 5 - 10 °C / minute.

[0094] Some embodiments according to the third aspect of the present invention provide an application of the above-mentioned loaded Ir nickel vanadium nitride as a catalyst or electrode for cathodic hydrogen evolution in alkaline water electrolysis for hydrogen production.

[0095] Some embodiments according to the third aspect of the present invention, when the loaded Ir NiV nitride is used as a catalyst or electrode for cathodic hydrogen evolution in alkaline water electrolysis for hydrogen production, the overpotential of the hydrogen evolution reaction can be reduced to 14 mV at a current density of 10 mA / cm 2 2.

[0096] In the present invention, the skeleton of the foam metal substrate (e.g., nickel foam) is a three-dimensional ordered skeleton, which is a macroporous structure itself. The catalyst supported on its surface is Ir-containing nickel vanadium nitride nanoparticles, belonging to microporous-mesoporous materials and arranged in an orderly manner. Therefore, according to the present invention, the Ir-supported nickel vanadium nitride can directly synthesize a three-dimensional ordered structure electrode, avoiding the use of adhesives.

[0097] When the Ir-supported nickel vanadium nitride according to the present invention is used for alkaline water electrolysis to produce hydrogen, it can optimize the adsorption and dissociation of water molecules, improve the adsorption of H* intermediates, and reduce the energy barrier, thereby improving the hydrogen evolution effect of the cathodic hydrogen evolution reaction.

[0098] Preparation Example 1

[0099] This example provides a preparation method of Ir-supported nickel vanadium nitride, and the preparation method includes the following steps:

[0100] S1) Cut a 1*1 cm 2 nickel foam, and alternately wash it with water, ethanol, acetone, water, 3 mol / L dilute hydrochloric acid, and water by ultrasonic wave for 5 minutes each. The washed nickel foam is reserved for later use;

[0101] S2) Take 0.12 g of NiCl2·6H2O (0.50 mmol), 0.04 g of VCl3 (0.25 mmol), and 0.075 g of urea (1.25 mmol) and dissolve them in 20 mL of deionized water, and stir evenly;

[0102] S3) Immerse the nickel foam washed in step S1 in the vanadium-nickel mixed solution prepared in step S2, transfer it to a 50 mL hydrothermal reaction kettle, and react at 120 °C for 12 hours; after the reaction, take out the nickel foam, wash it with water, absolute ethanol, and acetone for multiple times, and dry it in vacuum at 50 °C; obtain nickel foam supported NiV double metal hydroxide;

[0103] S4) Place the nickel foam supported NiV double metal hydroxide in step S3 in a plasma generator, introduce Ar gas, and activate it by plasma treatment for 5 minutes, where the plasma power is 50 W;

[0104] S5) Take out the nickel foam supported NiV double metal hydroxide activated in step S4, place it in an ethanol solution of 0.5 mmol / L IrCl3, soak it for 12 hours, then take it out and dry it in vacuum to obtain an Ir-supported NiV modified foam metal substrate;

[0105] S6) The electrode sheet after the treatment in step S5 (i.e., the Ir-loaded NiV modified foam metal substrate) is placed in a tube furnace at 360 °C and calcined for 3 hours, and pure ammonia gas is introduced as the reaction gas; after natural cooling, the ammoniaated electrode sheet is taken out, washed with water, and dried in vacuum at 50 °C to obtain an electrode sheet loaded with Ir nickel vanadium nitride.

[0106] Cut a piece of the above-mentioned electrode sheet loaded with Ir nickel vanadium nitride with a size of about 4*4 mm 2 sized electrode sheet for SEM-EDS characterization, and use SEM to observe the morphological characteristics of the precursor NiV double metal hydroxide. The results are as Figures 1 - 3 shown.

[0107] As Figure 1 shown, according to the scanning electron microscope (SEM) photo of the Ir-loaded NiV nitride electrode prepared in Example 1, it can be seen that the Ir-NiV nitride as a whole presents a multi-composite structure, which is composed of nanosheets composed of particles with a size of about 20-50 nm, and the diameter of the nanosheets is about 500-1000 nm, which inherits the morphological characteristics of the precursor NiV double metal hydroxide (as Figure 3 shown). Therefore, the nanoparticles are caused by the transformation of the product structure during the ammoniation process, that is, from NiV double metal hydroxide to NiV nitride oxide.

[0108] As Figure 2 shown, the electrode sample of Ir-loaded NiV nitride prepared in Example 1 contains elements Ni, V, Ir, O, and N, among which the mass loading of Ir accounts for about 4.77% (excluding the nickel foam substrate), and the molar ratio of Ni to N is about 3.1:1, corresponding to the Ni3N component therein, and the remaining part is mainly provided by VOx, where x = the atomic percentage content of O atoms / the atomic percentage content of V atoms = 1.6.

[0109] Application Example 1

[0110] This example provides the application of Ir-loaded nickel vanadium nitride. Specifically, the electrode sheet of Ir-loaded nickel vanadium nitride obtained in Preparation Example 1 is cut into a size of 0.5*1 cm 2 sized, in a three-electrode system, using 1.0 mol / L KOH as the electrolyte, Ag / AgCl as the reference electrode, and a carbon rod as the counter electrode to test the electrocatalytic hydrogen evolution performance of the catalyst. The results are as Figure 4 shown.

[0111] As Figure 4As shown, the hydrogen evolution polarization curve of the Ir-loaded NiV nitride electrode (abbreviation: Ir-NiV nitride) prepared according to Preparation Example 1 in 1.0 mol / L KOH (wherein, Ni foam is used as the substrate and there is internal resistance compensation). It can be seen that the overpotential corresponding to the Ir-loaded NiV nitride at a current density of 10 mA / cm 2 is only 14 mV.

[0112] Preparation Example 2

[0113] This example provides a method for preparing an Ir-loaded nickel vanadium nitride. The preparation method includes the following steps:

[0114] S1) Cut a 3*3 cm 2 nickel foam, and ultrasonically wash it alternately with water, ethanol, acetone, water, 3 mol / L dilute hydrochloric acid, and water for 5 minutes each. The washed nickel foam is reserved;

[0115] S2) Take 0.43 g of NiCl6·6H2O (1.8 mmol), 0.07 g of VCl3 (0.45 mmol), and 0.225 g of urea (3.75 mmol), dissolve them in 60 mL of deionized water, and stir evenly;

[0116] S3) Immerse the nickel foam washed in step S1 in the vanadium-nickel mixed solution prepared in step S2, transfer it to a 50 mL hydrothermal reaction kettle, and react at 140 °C for 12 hours; after the reaction, take out the nickel foam, wash it with water, absolute ethanol, and acetone multiple times, and dry it in vacuum at 50 °C; obtain nickel foam loaded with NiV double metal hydroxide;

[0117] S4) Place the nickel foam loaded with NiV double metal hydroxide in step S3 in a plasma generator, introduce Ar gas, and activate it by plasma treatment for 10 minutes. The plasma power is 80 W;

[0118] S5) Take out the nickel foam loaded with NiV double metal hydroxide activated in step S4, place it in an ethanol solution of 1 mmol / L IrCl3, soak it for 12 hours, then take it out and dry it in vacuum to obtain an Ir-loaded NiV modified foam metal substrate;

[0119] S6) Place the electrode sheet processed in step S5 (i.e., the Ir-loaded NiV modified foam metal substrate) in a tubular furnace at 380 °C and calcine it for 3 hours, introducing pure ammonia gas as the reaction gas; after natural cooling, take out the ammoniated electrode sheet, wash it with water, and dry it in vacuum at 50 °C to obtain an electrode sheet of Ir-loaded nickel vanadium nitride.

[0120] Cut the above-mentioned electrode sheet of Ir-loaded nickel vanadium nitride into about 4*4 mm 2Large and small electrode sheets were subjected to SEM-EDS characterization. The results showed that the Ir-loaded NiV oxynitride electrode prepared in this example had similar characteristics to the Ir-loaded NiV oxynitride electrode prepared in Example 1, that is, the Ir-NiV nitride as a whole presented a multiple composite structure, which was a nanosheet composed of particles with a diameter of about 20-50 nm, and the diameter of the nanosheet was about 500-1000 nm, inheriting the morphological characteristics of the precursor NiV double metal hydroxide. Therefore, the nanoparticles were caused by the transformation of the product structure during the ammoniation process, that is, from NiV double metal hydroxide to NiV oxynitride.

[0121] Preparation Example 3

[0122] This example provides a method for preparing an Ir-loaded nickel vanadium nitride, and the preparation method includes the following steps:

[0123] S1) Cut a 4*8 cm 2 nickel foam, and alternately wash it ultrasonically with water, ethanol, acetone, water, 3 mol / L dilute hydrochloric acid, and water for 5 minutes each. The washed nickel foam is reserved for use;

[0124] S2) Dissolve 0.95 g of NiCl6·6H2O (4 mmol), 0.31 g of VCl3 (2 mmol), and 1.2 g of urea (20 mmol) in 160 mL of deionized water and stir evenly;

[0125] S3) Immerse the nickel foam washed in step S1 in the vanadium-nickel mixed solution prepared in step S2, transfer it to a 200 mL hydrothermal reaction kettle, and react at 120 °C for 24 hours; after the reaction, take out the nickel foam, wash it with water, absolute ethanol, and acetone successively for multiple times, and dry it in vacuum at 50 °C; obtain nickel foam loaded with NiV double metal hydroxide;

[0126] S4) Place the nickel foam loaded with NiV double metal hydroxide in step S3 in a plasma generator, introduce Ar gas, and activate it by plasma treatment for 15 minutes. The plasma power is 100 W;

[0127] S5) Take out the nickel foam loaded with NiV double metal hydroxide activated in step S4, place it in an ethanol solution of 2 mmol / L IrCl3, soak it for 24 hours, then take it out and dry it in vacuum to obtain an Ir-loaded NiV modified foam metal substrate;

[0128] S6) Place the electrode sheet (i.e., the Ir-loaded NiV modified foam metal substrate) treated in step S5 in a tube furnace at 380 °C and calcine it for 3 hours, introducing pure ammonia gas as the reaction gas; after natural cooling, take out the ammoniated electrode sheet, wash it with water, and dry it in vacuum at 50 °C to obtain an electrode sheet of Ir-loaded nickel vanadium nitride.

[0129] Cut out an electrode sheet of the above-mentioned Ir-loaded nickel vanadium nitride with a size of about 4×4 mm 2 electrode sheet, and conduct SEM-EDS characterization. The results show that the Ir-loaded NiV oxynitride electrode prepared in this example has similar characteristics to the Ir-loaded NiV oxynitride electrode prepared in Example 1, that is, the Ir-NiV oxynitride as a whole presents a multiple composite structure, which is a nanosheet composed of particles with a size of about 20-50 nm, and the diameter of the nanosheet is about 500-1000 nm, inheriting the morphological characteristics of the precursor NiV double metal hydroxide. Therefore, the nanoparticles are caused by the transformation of the product structure during the ammoniation process, that is, from NiV double metal hydroxide to NiV oxynitride.

[0130] Prepare Comparative Example 1

[0131] This comparative example provides a method for preparing nickel vanadium nitride, which is different from Example 1 in that in step S5 of this comparative example, an ethanol solution is used instead of the ethanol solution of 0.5 mmol / L IrCl3, that is, the prepared nickel vanadium nitride electrode sheet in this comparative example is not loaded with Ir, abbreviated as NiV oxynitride.

[0132] Apply Comparative Example 1

[0133] This application comparative example provides an application of nickel vanadium nitride. Specifically, cut the electrode sheet prepared in Comparative Example 1 into 0.5×1 cm 2 size, in a three-electrode system, using 1.0 mol / L KOH as the electrolyte, Ag / AgCl as the reference electrode, and a carbon rod as the counter electrode, test the electrocatalytic hydrogen evolution performance of the catalyst, and the results are shown in Figure 4 NiV oxynitride in.

[0134] Apply Comparative Example 2

[0135] This application comparative example uses a commercial 20% Pt / C catalyst as the electrode sheet (abbreviated as 20% Pt / C), cut the electrode sheet into 0.5×1 cm 2 size, in a three-electrode system, using 1.0 mol / L KOH as the electrolyte, Ag / AgCl as the reference electrode, and a carbon rod as the counter electrode, test the electrocatalytic hydrogen evolution performance of the catalyst, and the results are as shown in Figure 4 shown in.

[0136] As shown in Figure 4As shown, the hydrogen evolution polarization curves of the Ir-loaded NiV oxide electrode (abbreviation: Ir-NiV oxide) prepared according to Preparation Example 1 and a commercial noble metal catalyst in 1.0 mol / L KOH (wherein Ni foam is used as the substrate and there is internal resistance compensation). It can be seen that the performance of the Ir-loaded NiV oxide is stronger than that of the control group without Ir. Its overpotential corresponding to a current density of 10 mA / cm 2 is only 14 mV, even exceeding that of the commercial 20% Pt / C catalyst (requiring an overpotential of 22 mV).

[0137] Therefore, the Ir-loaded NiV oxide electrode prepared in this example has excellent electrocatalytic hydrogen evolution performance in the process of alkaline electrolytic water hydrogen production.

Claims

1. A nickel vanadium nitride loaded with Ir, characterized in that, The Ir-loaded nickel vanadium nitride includes a vanadium-modified Ni3N support and a noble metal Ir supported on the vanadium-modified Ni3N support.

2. The Ir-loaded nickel vanadium nitride according to claim 1, wherein The Ir-loaded nickel vanadium nitride as a whole presents a multiple composite structure. The Ir-loaded nickel vanadium nitride is a nanosheet composed of nanoparticles with a size of 20-50 nm, and the diameter of the nanosheet is 500-1000 nm.

3. The Ir-loaded nickel vanadium nitride according to claim 2, wherein The nanoparticles are caused by the structural transformation of the product before and after ammoniation, that is, from NiV double metal hydroxide to NiV oxynitride.

4. The Ir-loaded nickel vanadium nitride according to claim 1, characterized in that, The Ir-loaded nickel vanadium nitride includes elements Ni, V, Ir, O and N. Among them, without considering the nickel foam substrate, the mass loading of Ir accounts for about 4.77% of the mass of the Ir-loaded nickel vanadium nitride. The total mass content of V element and O element is 26.66%, and the total mass content of N and Ni elements is 68.54%. The molar ratio of Ni to N is about 2.9-3.2:

1.

5. The Ir-loaded nickel vanadium nitride according to claim 4, characterized in that, The molar ratio of V element and O element is 1:1.60-1.

62.

6. A method for preparing Ir-loaded nickel vanadium nitride according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: 1) Dissolve nickel salt, vanadium salt and urea in water and stir evenly to obtain a vanadium-nickel mixed solution; 2) Immerse the foam metal substrate in the vanadium-nickel mixed solution for hydrothermal reaction to obtain a foam metal substrate loaded with NiV double metal hydroxide; 3) Place the NiV-modified foam metal substrate in a plasma generator and perform plasma activation treatment on it with Ar gas to obtain a plasma-activated NiV-modified foam metal substrate, so as to generate more vacancies and defects on the surface of the NiV double metal hydroxide for loading single atom clusters; 4) Impregnate the plasma-activated NiV-modified foam metal substrate with an Ir salt solution to obtain an Ir-loaded NiV-modified foam metal substrate; 5) Calcinate the Ir-loaded NiV-modified foam metal substrate at a high temperature in the presence of a reaction gas for ammoniation treatment to obtain the Ir-loaded nickel vanadium nitride.

7. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 6, characterized in that, The preparation method also includes the pretreatment of the foam metal substrate: wash the foam metal substrate to obtain a substrate with a clean surface; the foam metal substrate includes any one of nickel foam, nickel-cobalt foam, cobalt foam, iron foam, nickel-iron foam, nickel mesh and stainless steel mesh.

8. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 7, characterized in that, The pretreatment of the foam metal substrate includes: cutting a certain size of the foam metal substrate, and alternately washing the foam metal substrate with water, ethanol, acetone, water, dilute hydrochloric acid and water, and then set aside after washing.

9. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 8, wherein, In the pretreatment of the foam metal substrate, ultrasonic washing is performed on the foam metal substrate.

10. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 6, characterized in that, In the step 1), the nickel salt and the vanadium salt are in a total concentration of Ni 2+ and V 3+ of 35 to 50 mmol / L.

11. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 6, characterized in that, In the said step 1), the nickel salt and the vanadium salt are in a molar ratio of Ni 2+ and V 3+ of 2:1 to 4:

1.

12. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 6, characterized in that, In the step 1), the concentration of urea is 60-80 mmol / L.

13. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 6, characterized in that, In the step 1), the nickel salt includes nickel chloride, and the vanadium salt includes VCl3.

14. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 6, characterized in that, In the step 2), the reaction temperature of the hydrothermal reaction is 120-140 °C, and the reaction time is 12-24 hours.

15. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 6, characterized in that, The hydrothermal reaction also includes taking out the product generated after the hydrothermal reaction, washing it with water, absolute ethanol and acetone successively for multiple times, and drying it in vacuum.

16. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 6, characterized in that, In the step 3), the plasma power is 50-100 W, and the activation time is 5-15 minutes.

17. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 6, characterized in that, In the step 4), the impregnation solution is an ethanol solution of IrCl3, wherein the concentration of IrCl3 is 0.5 to 5 mmol / L.

18. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 6, characterized in that, In the step 5), the calcination temperature is 300 to 400 °C, the calcination time is 3 hours, and the heating rate is 5 to 10 °C / min; the reaction gas is ammonia gas.

19. The preparation method of the Ir-loaded nickel vanadium nitride according to claim 6, characterized in that, The step 5) further includes washing the ammoniated product and drying it under vacuum.

20. Use of the Ir-loaded nickel vanadium nitride according to any one of claims 1-5 as a cathode hydrogen evolution catalyst or electrode in alkaline water electrolysis for hydrogen production.

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