High-density iodine atom catalyst, preparation method and application thereof

Abstract

The application provides a preparation method of a high-density iodine monatomic catalyst, and comprises the following steps: A) iodizing carbon-coated nickel nanoparticles to obtain a high-density iodine monatomic catalyst. Compared with the prior art, the one-step iodization method of the application obtains a non-metallic iodine monatomic nanomaterial, which can not only avoid a complicated synthesis process, but also more importantly, significantly improves the monatomic loading density of the precursor carbon shell, and the unique non-metallic iodine monatomic regulation is conducive to giving the material excellent electrocatalytic hydrogen production activity and stability, and the process of the application is simple and easy to realize large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and particularly relates to a high-density iodine single-atom catalyst, its preparation method and application. Background Technology

[0002] Hydrogen energy is considered the most ideal new energy source due to its abundant raw materials, convenient storage and transportation, high calorific value, and pollution-free combustion products. Hydrogen production through water electrolysis in an alkaline medium has great potential in industrial hydrogen production and is of great significance in solving global energy shortages and environmental pollution problems.

[0003] Among existing catalysts for the hydrogen evolution reaction (HER) via water electrolysis, noble metal electrocatalysts such as Pt exhibit the highest activity but are expensive. Meanwhile, some single-atom metal catalysts (SACs) have attracted widespread attention due to their high atom utilization efficiency and good reaction selectivity. In particular, non-metallic SACs possess advantages such as low cost, simple synthesis methods, and effective substrate control. As a novel type of functional nanomaterial, their application in electrocatalysis has significant economic and scientific value, making them an emerging research hotspot. Furthermore, how to increase the loading of non-metallic single atoms without forming new phases is crucial for further improving the performance of non-metallic single-atom catalysts. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a high-density iodine single-atom catalyst with high activity and stability, its preparation method and application.

[0005] This invention provides a method for preparing a high-density iodine single-atom catalyst, comprising the following steps:

[0006] A) Carbon-coated nickel nanoparticles were iodized to obtain a high-density iodine single-atom catalyst.

[0007] Preferably, the carbon-coated nickel nanoparticles are prepared according to the following steps:

[0008] S1) An aminocarboxylic acid chelating agent is mixed with triethylamine in a first organic solvent to obtain solution 1;

[0009] The nickel salt was mixed with the second organic solvent to obtain solution 2;

[0010] S2) Mix solution 1 and solution 2, heat to react, and obtain nickel chelate;

[0011] S3) The nickel chelate is annealed to obtain carbon-coated nickel nanoparticles.

[0012] Preferably, the aminocarboxylic acid chelating agent is selected from ethylenediaminetetraacetic acid; the polyamine compound is selected from triethylamine.

[0013] The first organic solvent and the second organic solvent are N,N-dimethylformamide;

[0014] The nickel salt is selected from nickel chloride and / or nickel nitrate;

[0015] The molar ratio of the aminocarboxylic acid chelating agent to the nickel salt is 1:(1-3);

[0016] The molar ratio of the aminocarboxylic acid chelating agent to triethylamine is 1:(2-5).

[0017] Preferably, the heating reaction temperature in step S2) is 60℃~100℃; the heating reaction time is 0.5~3h;

[0018] In step S3), the annealing process is carried out in a protective atmosphere; the annealing temperature is 400℃~600℃; the annealing time is 1~3h; and the heating rate of the annealing process is 1~10℃ / min.

[0019] Preferably, step A) specifically comprises:

[0020] Carbon-coated nickel nanoparticles were placed without contact with an iodine source, and then iodized by heating in a reducing atmosphere to obtain a high-density iodine single-atom catalyst.

[0021] Preferably, the distance between the carbon-coated nickel nanoparticles and the iodine source is 15-25 cm; the iodine source is elemental iodine; the volume concentration of hydrogen in the reducing atmosphere is 10%-30%; the heating rate is 3-5 °C / min; the iodination temperature is 200 °C-300 °C; and the iodination time is 1-2 h.

[0022] The present invention also provides a high-density iodine single-atom catalyst, comprising carbon-coated nickel nanoparticles and iodine atoms supported on the carbon-coated nickel nanoparticles.

[0023] Preferably, the high-density iodine single-atom catalyst has a particle size of 5–10 nm and the iodine atom loading is 4–5 wt%.

[0024] The present invention also provides an application of the above-mentioned high-density iodine single-atom catalyst in electrocatalytic hydrogen production.

[0025] This invention also provides a method for preparing carbon-coated nickel nanoparticles, comprising the following steps:

[0026] S1) An aminocarboxylic acid chelating agent is mixed with triethylamine in a first organic solvent to obtain solution 1;

[0027] The nickel salt was mixed with the second organic solvent to obtain solution 2;

[0028] S2) Mix solution 1 and solution 2, heat to react, and obtain nickel chelate;

[0029] S3) The nickel chelate is annealed to obtain carbon-coated nickel nanoparticles.

[0030] This invention provides a method for preparing a high-density iodine single-atom catalyst, comprising the following steps: A) Iodizing carbon-coated nickel nanoparticles to obtain a high-density iodine single-atom catalyst. Compared with existing technologies, this invention directly obtains non-metallic iodine single-atom nanomaterials through a one-step iodization method. This not only avoids cumbersome synthesis processes but, more importantly, significantly improves the single-atom loading density by constructing a precursor carbon shell. Its unique non-metallic iodine single-atom regulation is beneficial for endowing the material with excellent electrocatalytic hydrogen production activity and stability. Furthermore, this invention has a simple process and is easily achievable for large-scale production.

[0031] Experiments show that the high-density iodine single-atom catalyst prepared in this invention exhibits excellent activity and stability in alkaline HER, with an overpotential of 78 mV @ 10 mA / cm. 2 At 20mA / cm 2 It can remain stable for up to 80 hours at a given current density, showing great promise for future applications. Attached Figure Description

[0032] Figure 1 The image is a scanning electron microscope (SEM) image of I-Ni@C prepared in Example 1 of this invention;

[0033] Figure 2 This is a transmission electron microscope (TEM) image of I-Ni@C prepared in Example 1 of the present invention;

[0034] Figure 3 The image shows the X-ray diffraction (XRD) pattern of I-Ni@C prepared in Example 1 of this invention.

[0035] Figure 4 The high-angle annular dark-field image-scanning transmission electron microscopy (HADDF) photograph of I-Ni@C prepared in Example 1 of the present invention;

[0036] Figure 5 X-ray near-edge absorption structure (XANES) of I-Ni@C prepared in Example 1 of this invention;

[0037] Figure 6 This is a diagram showing the X-ray absorption extension edge of I-Ni@C prepared in Example 1 of the present invention in R space;

[0038] Figure 7 The linear sweep voltammetry curve of I-Ni@C prepared in Example 1 of this invention;

[0039] Figure 8 This is a graph showing the electrochemical stability test of I-Ni@C prepared in Example 1 of this invention;

[0040] Figure 9 The above are linear sweep voltammetry curves of I-Ni@C prepared in Examples 2 to 5 of this invention. Detailed Implementation

[0041] The technical solutions 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.

[0042] This invention provides a method for preparing carbon-coated nickel nanoparticles, comprising the following steps: S1) mixing an aminocarboxylic acid chelating agent with triethylamine in a first organic solvent to obtain solution 1; mixing a nickel salt with a second organic solvent to obtain solution 2; S2) mixing solution 1 and solution 2 and heating to react to obtain a nickel chelate; S3) annealing the nickel chelate to obtain carbon-coated nickel nanoparticles.

[0043] This invention utilizes complexation precipitation and annealing methods to obtain carbon-coated nickel nanoparticles.

[0044] In this invention, there are no special restrictions on the source of any raw materials; they can be commercially available.

[0045] An aminocarboxylic acid chelating agent is mixed with triethylamine in a first organic solvent to obtain solution 1; the aminocarboxylic acid chelating agent preferably includes, but is not limited to, ethylenediaminetetraacetic acid; the molar ratio of the aminocarboxylic acid chelating agent to triethylamine is preferably 1:(2-5), more preferably 1:(3-4), and even more preferably 1:3.5; the first organic solvent is preferably N,N-dimethylformamide (DMF); the mixing is preferably carried out under heating conditions; the heating temperature is preferably 60℃-100℃, more preferably 70℃-90℃, even more preferably 75℃-85℃, and most preferably 80℃; the concentration of the aminocarboxylic acid chelating agent in solution 1 is preferably 0.01-0.1 mol / L, more preferably 0.03-0.08 mol / L, and even more preferably 0.06-0.07 mol / L.

[0046] The nickel salt is mixed with a second organic solvent to obtain solution 2; the nickel salt can be any inorganic nickel salt known to those skilled in the art, and there are no special restrictions. In this invention, nickel chloride and / or nickel nitrate are preferred; the second organic solvent is preferably N,N-dimethylformamide; the mixing is preferably carried out at room temperature.

[0047] The solutions 1 and 2 are mixed and heated to react. The molar ratio of the aminocarboxylic acid chelating agent to the nickel salt is preferably 1:(1-3), more preferably 1:(1.5-2.5), and even more preferably 1:2. The temperature of the heating reaction is preferably 60℃-100℃, more preferably 70℃-90℃, even more preferably 75℃-85℃, and most preferably 80℃. The heating reaction time is preferably 0.5-3h, more preferably 0.5-2h, and even more preferably 1h.

[0048] After heating and reaction, the product is preferably centrifuged, washed, and dried to obtain a nickel chelate. The washing is preferably done with DMF. The drying is preferably done under vacuum. The drying temperature is preferably 60℃~100℃, more preferably 70℃~90℃, even more preferably 75℃~85℃, and most preferably 80℃. The drying time is preferably 8~15h, more preferably 10~14h, and even more preferably 12h.

[0049] The nickel chelate is annealed to obtain carbon-coated nickel nanoparticles. The annealing is preferably performed in a protective atmosphere. Any protective atmosphere known to those skilled in the art is acceptable and is not particularly limited; in this invention, argon is preferred. The annealing temperature is preferably 400℃~600℃, more preferably 450℃~550℃, and even more preferably 500℃. The annealing time is preferably 1~3h, more preferably 1.5~2.5h, and even more preferably 2h (in this invention, unless otherwise specified, the annealing time refers to the holding time). The heating rate of the annealing is preferably 1~10℃ / min, more preferably 3~7℃ / min, and even more preferably 3~5℃ / min.

[0050] The present invention also provides a method for preparing a high-density iodine single-atom catalyst, comprising the following steps: A) iodizing carbon-coated nickel nanoparticles to obtain a high-density iodine single-atom catalyst.

[0051] This invention uses carbon-coated nickel nanoparticles as a precursor and employs a solid-phase thermal diffusion method to obtain a high-density iodine single-atom catalyst with uniform morphology.

[0052] The preparation method of the carbon-coated nickel nanoparticles is the same as described above, and will not be repeated here.

[0053] The iodine source for iodization is preferably elemental iodine; the mass ratio of the carbon-coated nickel nanoparticles to the iodine source is preferably (3-1):1, more preferably (2.5-2):1; the iodization is preferably carried out in a reducing atmosphere; the reducing atmosphere is preferably a mixture of a protective atmosphere and hydrogen; the protective atmosphere is preferably argon; the volume concentration of hydrogen in the reducing atmosphere is 10%-30%, more preferably 15%-25%, and even more preferably 20%; the heating rate is preferably 3-5℃ / min; the iodization temperature is preferably 200℃-300℃; and the iodization time is preferably 1-2 hours.

[0054] In this invention, this step is preferably specifically as follows: placing carbon-coated nickel nanoparticles without contacting an iodine source, and then heating in a reducing atmosphere to perform iodination, thereby obtaining a high-density iodine single-atom catalyst. The distance between the carbon-coated nickel nanoparticles and the iodine source is preferably 15-25 cm, more preferably 15-20 cm; the iodination is preferably carried out in a quartz tube; and the iodine source is preferably placed at the upper end.

[0055] This invention directly obtains non-metallic iodine single-atom nanomaterials through a one-step iodination method. This not only avoids the cumbersome synthesis process, but more importantly, it significantly improves the single-atom loading density by constructing a precursor carbon shell. Its unique non-metallic iodine single-atom regulation is beneficial to endowing the material with excellent electrocatalytic hydrogen production activity and stability.

[0056] The present invention also provides a high-density iodine single-atom catalyst, comprising carbon-coated nickel nanoparticles and iodine atoms supported on the carbon-coated nickel nanoparticles.

[0057] According to the present invention, the particle size of the high-density iodine single-atom catalyst is preferably 5-10 nm.

[0058] According to the present invention, the loading of iodine atoms in the high-density iodine single-atom catalyst is preferably 4-5 wt%, more preferably 4.5-5 wt%, and even more preferably 4.6 wt%.

[0059] The present invention also provides an application of the above-mentioned high-density iodine single-atom catalyst in electrocatalytic hydrogen production.

[0060] In this invention, the electrocatalytic hydrogen production is preferably alkaline electrocatalytic hydrogen production; the alkaline medium used for alkaline electrocatalytic hydrogen production is preferably an aqueous solution of alkali metal hydroxide; the aqueous solution of alkali metal hydroxide is preferably an aqueous solution of potassium hydroxide and / or an aqueous solution of sodium hydroxide; the concentration of the aqueous solution of alkali metal hydroxide is preferably 0.5 to 2 mol / L, more preferably 1 to 1.5 mol / L.

[0061] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, provides a high-density iodine single-atom catalyst, its preparation method, and its applications.

[0062] All reagents used in the following examples are commercially available.

[0063] Example 1

[0064] a. First, prepare the EDTA-Ni complex: Add 0.002 mol of ethylenediaminetetraacetic acid (EDTA) and 1.0 ml of triethylamine to 30.0 ml of N,N-dimethylformamide (DMF), and stir on an 80°C stirrer until completely dissolved; this solution is named Solution 1. Add 0.004 mol of Ni(NO3)2·6H2O to 20.0 ml of DMF, and stir at room temperature until completely dissolved; this solution is named Solution 2. Then, mix Solution 1 and Solution 2, and stir on an 80°C stirrer for 1 h to obtain a suspension. Centrifuge the suspension to obtain a precipitate, wash three times with DMF, and finally dry in a vacuum at 80°C for 12 h. The resulting pale blue powder is the EDTA-Ni complex.

[0065] b. Annealing is performed using the EDTA-Ni described above. During annealing, a quartz tube is used, with the EDTA-Ni placed in the middle of the quartz tube. The annealing is carried out in an argon gas atmosphere, with a heating rate of 5℃ / min, until the temperature reaches 500℃ and is maintained for 2 hours, thereby obtaining the desired carbon-coated nickel nanoparticles (Ni@C).

[0066] c. After obtaining the desired crude carbon-coated nickel nanoparticle material, this embodiment of the invention further prepares a non-metallic iodine single-atom catalyst I-Ni@C. The specific method includes: using atomic thermal diffusion, Ni@C and elemental iodine (I2) in a mass ratio of 2:1 are placed in the middle of a quartz tube and at an appropriate position at the gas inlet, respectively, with a distance of 15 cm between them. Preferably, a 20% Ar / H2 mixed gas is continuously introduced. After 30 minutes, the temperature is programmed to rise to 200°C at a rate of 5°C / min. After stabilization, the temperature is maintained for 1 hour. After cooling, an I-Ni@C electrocatalyst that can be used for alkaline water electrolysis to produce hydrogen is obtained.

[0067] d. The obtained I-Ni@C was characterized in terms of morphology and its electrochemical performance was tested. Specifically, the obtained electrocatalyst I-Ni@C was placed in a 1.0 M KOH solution, and its electrochemical performance was tested at the laboratory level using an electrochemical workstation (CHI760E).

[0068] Figure 1 The image shown is a scanning electron microscope (SEM) image of I-Ni@C prepared in Example 1. The SEM image shows that I-Ni@C consists of nanoparticles with a diameter in the range of 5 to 10 nm.

[0069] Figure 2The image shown is a transmission electron microscope (TEM) image of I-Ni@C prepared in Example 1. The TEM image confirms the core-shell structure of this nanoparticle. Measurement of the interplanar spacing further confirms that the core of this core-shell structure is Ni and the shell is C. No other obviously aggregated nanoparticles were found, indicating that I has good dispersion.

[0070] Figure 3 The image shows the X-ray diffraction (XRD) pattern of I-Ni@C prepared in Example 1. The XRD pattern visually indicates that the main phase of the obtained catalyst is Ni, with no phase related to I, and further demonstrates the atomic-level dispersion of I.

[0071] Figure 4 The image shown is a high-angle annular dark-field image-scanning transmission electron microscopy (HADDF) photograph of I-Ni@C prepared in Example 1, where the bright spots marked by red circles represent iodine single atoms.

[0072] Figure 5 and Figure 6 The results are X-ray absorption fine structure (XAFS) spectra of I-Ni@C prepared in Example 1. X-ray absorption fine structure (XAFS) confirms that no II bonds are formed in the obtained catalyst I-Ni@C. Figure 5 This is a diagram of the near-edge absorption structure (XANES) of X-rays. Figure 6 The X-ray absorption extension edge is shown in R-space.

[0073] Figure 7 The linear sweep voltammetry curve of I-Ni@C prepared in Example 1 is shown in the figure. Compared with the control sample and the noble metal Pt, I-Ni@C exhibits a voltage of 78 mV@10 mA / cm². 2 Its excellent overpotential is similar to that of noble metal Pt catalysts.

[0074] Figure 8 The image shows the electrochemical stability test curve of I-Ni@C prepared in Example 1. In this experiment, it was placed in an alkaline electrolyte (1.0 M KOH) at 20 mA / cm². 2 Electrolysis was performed continuously for 80 hours at the specified current density without significant performance degradation, far exceeding a series of comparative samples and precious metal Pt catalysts.

[0075] Comparative Example 1

[0076] Preparation of Ni nanoparticles: 0.003 mol of NiCl2·6H2O was added to 40.0 ml of N,N-dimethylformamide (DMF), stirred until fully dissolved, and then transferred to a reaction vessel. The mixture was kept at 160 °C for 12 h. After the reaction vessel cooled to room temperature, the suspension was centrifuged to obtain the precipitate, which was washed three times with water and ethanol respectively. Finally, it was dried in a vacuum at 60 °C for 12 h.

[0077] The difference between this comparative example and Example 1 is that the precursor for thermal diffusion is replaced by Ni instead of Ni@C; otherwise, it is the same as Example 1, and the resulting product is denoted as I-Ni.

[0078] Example 2

[0079] The difference between this embodiment and Example 1 is that the mass of iodine is replaced with 100 mg; otherwise, they are the same as in Example 1.

[0080] Example 3

[0081] The difference between this embodiment and Embodiment 1 is that the position of elemental iodine is adjusted to 20 cm away from the crude carbon tube; otherwise, it is the same as Embodiment 1.

[0082] Example 4

[0083] The difference between this embodiment and Embodiment 1 is that a mixed gas atmosphere of 5% Ar / H2 is introduced; otherwise, it is the same as Embodiment 1.

[0084] Example 5

[0085] The difference between this embodiment and Embodiment 1 is that in step c, the temperature is increased to 300°C at a rate of 3°C / min and maintained at this temperature for 2 hours; otherwise, it is the same as Embodiment 1.

[0086] The electrocatalysts I-Ni@C prepared in Examples 2-5 were placed in 1.0 M KOH solution, and their electrochemical performance was tested at the laboratory level using an electrochemical workstation (CHI760E). The linear sweep voltammetry curves were obtained, as shown below. Figure 9 As shown.

[0087] Due to limitations in diffusion amount, diffusion path, diffusion gas atmosphere, and diffusion kinetics, the experimental results obtained in Comparative Example 1 and Examples 2-5 above showed a decrease in performance compared to the preferred conditions in Example 1.

[0088] As demonstrated by the above embodiments, the nickel nanoparticles directly coated with a carbon iodide shell of the present invention yield a non-metallic iodine single-atom catalyst (I-Ni@C). Compared to I-Ni obtained directly from nickel nanoparticles with carbon iodide shell, I-Ni@C exhibits approximately twice the single-atom loading density, proving the universality of the solid-phase thermal diffusion method and demonstrating that the construction of the precursor carbon shell significantly improves the single-atom loading density. The obtained I-Ni@C exhibits excellent activity and stability in alkaline HER, with an overpotential of 78 mV@10 mA / cm². 2 At 20mA / cm 2It can remain stable for up to 80 hours at a given current density. The electrocatalyst prepared in this invention has the advantages of simple and economical synthesis and excellent performance, which is of great significance for the design and application of non-metallic single-atom catalysts and has great application prospects.

[0089] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various modifications to these embodiments without departing from the technical principles of the present invention, and these modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-density iodine single-atom catalyst, characterized in that, Includes the following steps: Carbon-coated nickel nanoparticles were placed without contact with an iodine source, and then iodized by heating in a reducing atmosphere to obtain a high-density iodine single-atom catalyst. The mass ratio of the carbon-coated nickel nanoparticles to the iodine source is (3~1):1; The distance between the carbon-coated nickel nanoparticles and the iodine source is 15-25 cm; the iodine source is elemental iodine; the volume concentration of hydrogen in the reducing atmosphere is 10%-30%; the heating rate is 3-5℃ / min; the iodination temperature is 200℃-300℃; and the iodination time is 1-2 h.

2. The preparation method according to claim 1, characterized in that, The carbon-coated nickel nanoparticles were prepared according to the following steps: S1) Ethylenediaminetetraacetic acid and triethylamine are mixed in a first organic solvent to obtain solution 1; The nickel salt was mixed with the second organic solvent to obtain solution 2; S2) Mix solution 1 and solution 2, heat to react, and obtain nickel chelate; S3) The nickel chelate is annealed to obtain carbon-coated nickel nanoparticles.

3. The preparation method according to claim 2, characterized in that, The first organic solvent and the second organic solvent are N,N-dimethylformamide; The nickel salt is selected from nickel chloride and / or nickel nitrate; The molar ratio of ethylenediaminetetraacetic acid to nickel salt is 1:(1~3); The molar ratio of ethylenediaminetetraacetic acid to triethylamine is 1:(2~5).

4. The preparation method according to claim 2, characterized in that, The heating temperature in step S2) is 60℃~100℃; the heating time is 0.5~3 h. In step S3), the annealing process is carried out in a protective atmosphere; the annealing temperature is 400℃~600℃; the annealing time is 1~3 h; and the heating rate of the annealing process is 1~10℃ / min.

5. A high-density iodine single-atom catalyst prepared by the method of claim 1, characterized in that, This includes carbon-coated nickel nanoparticles and iodine atoms loaded on the carbon-coated nickel nanoparticles.

6. The high-density iodine single-atom catalyst according to claim 5, characterized in that, The high-density iodine single-atom catalyst has a particle size of 5-10 nm and an iodine atom loading of 4-5 wt%.

7. The application of the high-density iodine single-atom catalyst prepared by any one of claims 1 to 4 or the high-density iodine single-atom catalyst according to claim 5 or 6 in electrocatalytic hydrogen production.

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