A nickel nitride supported Ru atomic catalyst, a preparation method thereof and application as an electrochemical hydrogen evolution reaction catalyst

Abstract

The application provides a nickel nitride supported Ru atomic catalyst, a preparation method thereof and application thereof as an electrochemical hydrogen evolution reaction catalyst. The catalyst is prepared by a hydrothermal reaction method and a chemical vapor deposition method, and comprises a nickel nitride carrier and Ru atoms supported on the nickel nitride carrier. Through electrochemical activity testing, it is found that, compared with a commercial Pt / C catalyst, the nickel nitride supported Ru atomic catalyst has better catalytic performance based on noble metal normalization, higher activity and lower cost, and can realize atomic economic catalytic effect. In addition, through electrochemical stability testing, it is found that, after continuous electrolysis for 100 hours, the activity of the nickel nitride supported Ru atomic catalyst is basically unchanged, and meanwhile, the morphology and phase of the nickel nitride supported Ru atomic catalyst can also be well maintained after the reaction.

Description

Technical Field

[0001] This invention belongs to the fields of materials chemistry and electrocatalysis, specifically relating to a nickel nitride-supported Ru atom catalyst, its preparation method, and its application as a catalyst for the electrochemical hydrogen evolution reaction. Background Technology

[0002] Hydrogen (H2) has a high energy density (142 MJ·kg⁻¹). -1 Hydrogen is a very clean and viable alternative energy source, and its combustion product is only water. Therefore, vigorously developing the proportion of hydrogen energy in the future energy structure is an important way to achieve "carbon peaking" and "carbon neutrality." Currently, hydrogen production through water electrolysis driven by wind and solar power is the most promising method for producing "green hydrogen," but it suffers from high energy consumption and high production costs, especially the high cost of catalysts, which severely limits its application. Therefore, developing inexpensive, efficient, and stable hydrogen evolution catalysts has significant economic and scientific value.

[0003] Currently, platinum-based catalysts are the most active catalysts for hydrogen production through water electrolysis. Their low reserves lead to high prices, hindering large-scale industrial production. Developing efficient and inexpensive catalysts is of greater research significance for hydrogen production through water electrolysis. There are two main research directions for hydrogen production catalysts through water electrolysis: reducing the amount of platinum used in platinum-based catalysts and developing inexpensive and efficient non-platinum-based catalysts. Although significant progress has been made in the research of non-platinum-based catalysts, especially transition metal nitride nanomaterials, whose Pt-like electronic structure endows them with excellent hydrogen adsorption-desorption activity, thus exhibiting good electrocatalytic hydrogen production performance, they still lag far behind platinum-based catalysts in terms of catalytic activity and stability. Furthermore, for electrochemical hydrogen evolution under alkaline conditions, it is necessary to consider not only the catalyst material's hydrogen adsorption activity but, more importantly, its ability to dissociate water molecules. Compared to Pt, Ru has higher water dissociation activity, but Ru is also more expensive. Currently, most research involves loading Ru atoms onto carbon substrates; however, due to the low activity of carbon itself, the overall activity of such composite materials is not high enough. Therefore, there is an urgent need to develop new supports to improve the activity and utilization of noble metal Ru atoms, and to prepare efficient and low-cost electrocatalytic hydrogen production catalysts. Summary of the Invention

[0004] In view of this, the present invention aims to provide a nickel nitride-supported Ru atom catalyst, its preparation method, and its application as a catalyst for the electrochemical hydrogen evolution reaction. The catalyst can be used in the alkaline hydrogen evolution reaction, and compared to commercially available Pt / C (20 wt%), its catalytic performance based on the mass activity of noble metal atoms is greatly improved, while also being inexpensive and exhibiting good stability.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a nickel nitride-supported Ru atom catalyst, comprising a nickel nitride support and Ru atoms supported on the nickel nitride support.

[0007] Preferably, the Ru atoms include Ru monoatoms and / or Ru atom clusters.

[0008] Preferably, the Ru atom content in the catalyst is 0.08–1 at%.

[0009] Secondly, the present invention provides a method for preparing the above-mentioned catalyst, comprising the following steps:

[0010] The nickel salt, basic regulator, ruthenium salt and solvent are mixed and subjected to a hydrothermal reaction to obtain an intermediate. The intermediate is then subjected to nitriding treatment to obtain the catalyst.

[0011] Preferably, the nickel salt is selected from one or more of nickel nitrate, nickel chloride, or nickel sulfate.

[0012] Preferably, the alkalinity regulator is selected from urea and / or ammonium fluoride.

[0013] Preferably, the ruthenium salt is selected from ruthenium acetylacetonate and / or ruthenium chloride.

[0014] Preferably, the solvent is selected from water.

[0015] Preferably, the mass ratio of the nickel salt, alkaline regulator, ruthenium salt, and solvent is (580–582):(660–662):(1–5):40.

[0016] Preferably, the hydrothermal reaction is carried out at a temperature of 100–150°C for 4–10 hours.

[0017] Preferably, the nitrogen source for the nitriding treatment is selected from any one or more of urea, ammonia, or nitrogen.

[0018] Preferably, the nitriding treatment is performed at a temperature of 300–400°C for 1–3 hours.

[0019] Thirdly, the present invention provides a working electrode for electrocatalytic hydrogen production, comprising a conductive substrate and a catalyst composited with the conductive substrate, wherein the catalyst is the catalyst involved in the above-mentioned technical solution.

[0020] Preferably, the conductive substrate is selected from one or more of nickel foam, carbon cloth, or carbon paper.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention prepares a self-supporting nickel nitride-supported Ru atom catalyst using hydrothermal reaction and chemical vapor deposition. The Ru atoms include Ru single atoms and / or Ru atom clusters, achieving control over the local environment of Ru atoms. The nickel nitride-supported Ru atom catalyst can be directly supported on a conductive substrate and used as an electrode in an electrolytic cell, avoiding problems such as slow diffusion rate and poor conductivity caused by the use of binders, while also simplifying the electrode fabrication process. Electrochemical activity tests show that, compared with commercial Pt / C catalysts, the nickel nitride-supported Ru atom catalyst provided by this invention exhibits better catalytic performance based on noble metal normalization, higher activity, and lower cost, achieving atom-economical catalytic effects. Furthermore, electrochemical stability tests show that the activity of the nickel nitride-supported Ru atom catalyst provided by this invention remains essentially unchanged after 100 hours of continuous electrolysis, and its morphology and phase are also well preserved after the reaction. Attached Figure Description

[0023] Figure 1 The X-ray diffraction pattern of the working electrode prepared in Example 1 of this invention;

[0024] Figure 2 This is a SEM image of the working electrode prepared in Example 1 of the present invention;

[0025] Figure 3 The R-space distribution diagram of the EXAFS signal of the Fourier transform of the working electrode prepared in Embodiment 1 of the present invention;

[0026] Figure 4 A comparison of linear sweep voltammetry curves of the working electrode prepared in Example 1 of this invention and a commercial Pt / C catalyst as the working electrode;

[0027] Figure 5 This is a comparison chart of the stability test results of the working electrode prepared in Example 1 of the present invention and a commercial Pt / C catalyst as the working electrode;

[0028] Figure 6 The above are comparison graphs of linear scanning voltammetry curves of the working electrodes prepared in Examples 1-3 of this invention. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] To address the issues of high cost of platinum-based water electrolysis catalysts and the need to improve the catalytic activity and stability of non-platinum-based water electrolysis catalysts in existing technologies, this invention provides a nickel nitride-supported Ru atom catalyst, comprising a nickel nitride support and Ru atoms supported on the nickel nitride support. Studies have shown that the catalyst contains Ru-N, Ru-Ni, and Ru-Ru bonds, indicating that the Ru atoms include Ru single atoms and / or Ru atom clusters, preferably including both Ru single atoms and Ru atom clusters. Compared to a single Ru single atom or Ru atom cluster, the mixed existence of Ru single atoms and clusters reduces charge transfer impedance, resulting in a catalyst with superior catalytic performance. In this invention, studies have shown that when the Ru atom content in the nickel nitride-supported Ru atom catalyst is 0.08–1 at%, the catalyst has a low overpotential, resulting in good catalytic performance. In some embodiments of this invention, the Ru atom content in the catalyst is preferably 0.09–0.8 at%, more preferably 0.09–0.6 at%, and most preferably 0.19 at%.

[0031] This invention provides a catalyst for hydrogen production via water electrolysis. It uses nickel nitride as a support to load Ru atoms onto a conductive substrate, allowing it to be directly used as the working electrode in an electrolyzer. Alkaline electrocatalytic hydrogen production performance testing revealed that, at high current densities, the overpotential of the catalyst provided by this invention is close to that of commercially available Pt / C catalysts, but the amount of precious metal used is reduced by nearly 100 times, indicating better catalytic performance, higher economic efficiency, and better stability. After 100 hours of continuous electrolysis, the activity remains essentially unchanged.

[0032] The nickel nitride-supported Ru atom catalyst provided by this invention is prepared by hydrothermal reaction and chemical vapor deposition, specifically including the following experimental steps:

[0033] The nickel salt, basic regulator, ruthenium salt and solvent are mixed and subjected to a hydrothermal reaction to obtain an intermediate. The intermediate is then subjected to nitriding treatment to obtain the catalyst.

[0034] According to the present invention, a nickel salt, an alkaline regulator, a ruthenium salt, and a solvent are first mixed and subjected to a hydrothermal reaction to obtain an intermediate. In this invention, the nickel salt is selected from any one or more of nickel nitrate, nickel chloride, or nickel sulfate; the alkaline regulator is selected from urea and / or ammonium fluoride; the ruthenium salt is selected from ruthenium acetylacetonate and / or ruthenium chloride; and the solvent is selected from water. In some embodiments of the present invention, the concentration of the nickel salt in the mixed solution composed of the nickel salt, the alkaline regulator, the ruthenium salt, and the solvent is 0.02–0.08 mol / L, preferably 0.05–0.06 mol / L. The concentration of the ruthenium salt in the mixed solution composed of the nickel salt, the alkaline regulator, the ruthenium salt, and the solvent is 0.03–0.8 mol / L, preferably 0.05–0.5 mol / L. In some embodiments of the present invention, the nickel salt, alkaline regulator, ruthenium salt and solvent are preferably added to a hydrothermal reactor in a mass ratio of (580-582):(660-662):(1-5):40, and reacted at 100-150°C for 4-10 hours to obtain an intermediate.

[0035] After obtaining the intermediate, it is subjected to nitriding to obtain the nickel nitride-supported Ru atom catalyst. In some embodiments of the present invention, the intermediate is preferably washed and dried. The washing agent is selected from water and / or anhydrous ethanol, and the washing is performed 3 to 10 times. The drying is carried out in a conventional instrument at a temperature of 40 to 60°C. Then, the dried intermediate is subjected to nitriding. In some embodiments of the present invention, the nitriding is carried out in a tube furnace at 300 to 400°C for 1 to 3 hours, and the nitrogen source for the nitriding is selected from any one or more of urea, ammonia, or nitrogen.

[0036] The preparation method of the nickel nitride-supported Ru atom catalyst provided by the present invention is simple and easy to operate, and can achieve the control of the local environment of Ru atoms, which is conducive to industrial production.

[0037] The present invention also provides a working electrode for electrocatalytic hydrogen production, comprising a conductive substrate and a catalyst composited with the conductive substrate, wherein the catalyst is the catalyst involved in the above-described technical solutions. In some embodiments of the present invention, the conductive substrate is selected from any one or more of nickel foam, carbon cloth, or carbon paper.

[0038] To further illustrate the present invention, the following embodiments provide a detailed description. The experimental materials used in the following embodiments of the present invention can be purchased commercially or prepared using conventional methods well-known to those skilled in the art.

[0039] Example 1

[0040] This embodiment provides a working electrode for an electrocatalytic hydrogen production catalyst, the preparation method of which is as follows:

[0041] Weigh 0.29079 g of nickel nitrate and dissolve it in 20 mL of deionized water to form a homogeneous solution. Then add 0.2643 g of urea and 0.0667 g of ammonium fluoride and stir for 0.5 h to form a homogeneous solution. Finally, add 0.5 mg of RuCl3. Transfer the prepared solution to a 25 mL polytetrafluoroethylene hydrothermal reactor. Place a 2 cm × 3 cm piece of hydrophilic carbon in the reactor. Place it in a stainless steel reactor shell, tighten the lid, and react in an oven at 120 °C for 9 h to obtain a ruthenium-doped nickel hydroxide precursor grown on carbon cloth. Shake and clean the carbon cloth, then dry it in a vacuum drying oven at 60 °C. Nitride it in a tube furnace at 400 °C for 2 h using ammonia as the carrier gas and nitrogen source to obtain the working electrode of the electrocatalytic hydrogen production catalyst.

[0042] Inductively coupled plasma atomic absorption spectrometry was performed on the working electrode of the obtained electrocatalytic hydrogen production catalyst. The atomic ratio of Ru in the catalyst was calculated to be 0.19 at%.

[0043] X-ray diffraction tests were performed on the working electrode and nickel nitride of the obtained electrocatalytic hydrogen production catalyst, and the resulting spectra are shown below. Figure 1 As shown, the catalyst has the same structure as hexagonal nickel nitride crystals.

[0044] SEM analysis was performed on the working electrode of the obtained electrocatalytic hydrogen production catalyst, and the images are as follows: Figure 2 As shown, the catalyst has a layered structure.

[0045] The local structure of ruthenium in the working electrode of the obtained electrocatalytic hydrogen production catalyst was analyzed, and the results are as follows: Figure 3 As shown, Ru-N, Ru-Ni, and Ru-Ru bonds exist in the catalyst, indicating that ruthenium exists in the catalyst in the form of single atoms and clusters.

[0046] The alkaline electrocatalytic hydrogen production performance of the working electrode of the obtained electrocatalytic hydrogen production catalyst was tested, and the specific method is as follows:

[0047] Electrochemical data were collected using a CHI660e electrochemical workstation. A three-electrode electrolytic cell was used for testing. The working electrode was the electrocatalyst for hydrogen production prepared above, the reference electrode was an Ag / AgCl electrode, the counter electrode was a carbon rod electrode, and the electrolyte was a 1.0 M KOH solution.

[0048] Activity test: linear sweep voltammetry curve, scan rate 5mV / s;

[0049] Stability testing: Timing potential analysis, with a current density of 10 mA / cm². 2 The test lasted for 100 hours, and the voltage curve under constant current density was recorded for 100 consecutive hours.

[0050] Activity test results as follows Figure 4 As shown, the linear sweep voltammetry curve results based on area normalization indicate that at a current density of 10 mA / cm², -2 At that time, the overpotential of the ruthenium single-atom / cluster catalyst supported on nickel nitride nanosheets was very close to that of commercial Pt / C (20 wt%).

[0051] Stability test results are as follows Figure 5 As shown, the ruthenium single-atom / cluster catalyst supported on nickel nitride nanosheets exhibits higher stability than Pt / C.

[0052] In summary, the ruthenium single-atom / cluster catalyst (Ru-Ni3N) supported on nickel nitride nanosheets prepared in this invention exhibits superior activity and stability compared to currently commercially available Pt / C catalysts for alkaline electrocatalytic hydrogen production.

[0053] Example 2

[0054] This embodiment provides a working electrode for an electrocatalytic hydrogen production catalyst. Compared with Example 1, the only difference is that the amount of RuCl3 added is 0.125 mg, while the other parameters and steps are the same as in Example 1.

[0055] Inductively coupled plasma atomic absorption spectrometry was performed on the working electrode of the obtained electrocatalytic hydrogen production catalyst. The calculated atomic content of Ru in the catalyst was 0.09 at%.

[0056] Example 3

[0057] This embodiment provides a working electrode for an electrocatalytic hydrogen production catalyst. Compared with Example 1, the only difference is that the amount of RuCl3 added is 2.5 mg, while the other parameters and steps are the same as in Example 1.

[0058] Inductively coupled plasma atomic absorption spectrometry was performed on the working electrode of the obtained electrocatalytic hydrogen production catalyst. The calculated atomic content of Ru in the catalyst was 0.60 at%.

[0059] Referring to the alkaline electrocatalytic hydrogen production performance testing method in Example 1, the working electrodes obtained in Examples 2 and 3 were tested, and the results were compared with those of the working electrode obtained in Example 1. The results are as follows: Figure 6As shown, the catalyst activity reached its optimum when the Ru content was 0.19 at%, and further increasing the Ru content did not significantly improve the catalytic performance. Specifically, when the Ru content was 0.09 at% (Example 2), the catalyst activity was optimal at a current density of 10 mA / cm². 2 and 50mA / cm 2 At these values, the overpotentials were 164 mV and 230 mV, respectively. When the Ru content was 0.60 at% (Example 3), the overpotential was 10 mA / cm². 2 and 50mA / cm 2 The overpotentials are 55mV and 111mV, respectively.

[0060] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A nickel nitride supported Ru atomic catalyst, characterized in that, The Ru atom includes Ru monatomic and / or Ru atomic cluster. The preparation method of the catalyst comprises the following steps: mixing a nickel salt, an alkaline regulator, a ruthenium salt and a solvent, and then performing hydrothermal reaction to obtain an intermediate, and then performing nitriding treatment on the intermediate to obtain the catalyst; The mass ratio of the nickel salt, the alkaline regulator, the ruthenium salt and the solvent is (580-582):(660-662):(1-5):

40. The catalyst contains Ru-N, Ru-Ni and Ru-Ru bonds. The content of the Ru atom in the catalyst is 0.19 at%.

2. The catalyst according to claim 1, characterized in that, The Ru atom includes Ru monatomic and / or Ru atomic cluster.

3. The method of preparing a catalyst according to claim 1 or 2, characterized in that, The preparation method comprises the following steps: mixing a nickel salt, an alkaline regulator, a ruthenium salt and a solvent, and then performing hydrothermal reaction to obtain an intermediate, and then performing nitriding treatment on the intermediate to obtain the catalyst.

4. The production method according to claim 3, characterized by, The nickel salt is selected from any one or more of nickel nitrate, nickel chloride or nickel sulfate; The alkaline regulator is selected from urea and / or ammonium fluoride; The ruthenium salt is selected from ruthenium acetylacetonate and / or ruthenium chloride; The solvent is selected from water.

5. The preparation method according to claim 3, characterized in that, The mass ratio of the nickel salt, the alkaline regulator, the ruthenium salt and the solvent is (580-582):(660-662):(1-5):

40.

6. The preparation method according to claim 3, characterized in that, The temperature of the hydrothermal reaction is 100-150 DEG C, and the time is 4-10 h.

7. The preparation method according to claim 3, characterized in that, The nitrogen source of the nitriding treatment is selected from any one or more of urea, ammonia or nitrogen; The temperature of the nitriding treatment is 300-400 DEG C, and the time is 1-3 h.

8. A working electrode for electrocatalytic hydrogen generation, characterized in that, The catalyst is the catalyst of claim 1 or 2 or the catalyst prepared according to the preparation method of any one of claims 3-7.

9. The working electrode of claim 8, wherein, The conductive substrate is selected from any one or more of nickel foam, carbon cloth or carbon paper.

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