Preparation method and application of iron-loaded electron-rich black phosphorus nanosheet electrocatalyst

Abstract

The invention belongs to the field of new energy electrocatalytic materials, and particularly relates to a preparation method and application of an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst, S1, tetrabutylammonium bromide and iron salt are dissolved in an acetonitrile solvent to obtain an electrolyte; s2, taking the black phosphorus block as a cathode and a platinum sheet as an anode, immersing the black phosphorus block and the platinum sheet in an electrolyte, and applying voltage by adopting a direct-current power supply to carry out electrochemical intercalation and stripping; and S3, carrying out ultrasonic treatment, washing and vacuum drying on the solution obtained in the step S2 to obtain the iron-loaded electron-rich black phosphorus nanosheet electrocatalyst. The invention also provides an application of the iron-loaded electron-rich black phosphorus nanosheet electrocatalyst prepared by the preparation method in electrocatalytic water desorption and oxygen desorption in an alkaline electrolyte. The catalytic material shows excellent electro-catalytic oxygen evolution activity and good catalytic stability in alkaline electrolyte.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy electrocatalytic materials, and in particular to a preparation method and application of an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst. Background Art

[0002] In the context of the increasingly severe global climate change and carbon emission problems, countries are accelerating the transformation of the energy structure towards low-carbon energy, and the demand for renewable energy technologies is growing exponentially. Hydrogen has the advantages of high energy density (142 MJ / kg), zero carbon emissions during combustion, and strong renewability, and is considered an important direction for future energy transformation. Therefore, hydrogen production by electrolysis of water has received extensive attention as a clean energy technology. The anodic oxygen evolution reaction of electrolysis of water includes four steps of proton-coupled electron transfer elementary steps, and its kinetics is very slow. Noble metal-based catalysts (such as iridium, ruthenium, etc.) have excellent electrocatalytic activity, which can significantly reduce the overpotential of the oxygen evolution reaction, thereby improving the efficiency of electrolysis of water. Although noble metal-based catalysts have good catalytic performance, noble metals are scarce resources and very expensive, making it difficult to meet the demand for large-scale hydrogen production by electrolysis of water. Therefore, developing new non-noble metal-based electrocatalytic oxygen evolution catalysts is the core path to replace the noble metal system and promote the large-scale application of hydrogen production technology by electrolysis of water.

[0003] In recent years, as a new type of two-dimensional material, black phosphorus-based materials have made remarkable progress in the application research in the field of electrocatalysis. Black phosphorus is one of the allotropes of phosphorus, and its unique layered structure (similar to the "armchair" shape) is formed by the sp 3 hybridization of phosphorus atoms, with characteristics such as high carrier mobility, controllable bandgap, and adjustable electronic structure, making it a potential candidate material to replace traditional noble metal catalysts. For example, the Chinese patent document with the publication number CN118577289A discloses a preparation method of single-atom-loaded black phosphorus nanosheets. In this method, metal cations are anchored in black phosphorus nanosheets rich in lone pairs of electrons through cation-π interactions, and then metal single-atom-loaded black phosphorus nanosheets are obtained through heat treatment. The introduction of single atoms significantly improves the environmental stability of black phosphorus nanosheets and at the same time enhances their photoelectrocatalytic performance. For example, the Chinese patent document with the publication number CN114808019A discloses an in-situ preparation method of a transition metal / black phosphorus electrocatalyst. This method uses electrochemistry to exfoliate black phosphorus bulk into black phosphorus and in-situ load transition metals on black phosphorus, enhancing the bifunctional catalytic activity of hydrogen evolution and oxygen evolution of black phosphorus-based materials.

[0004] However, at present, the catalytic activity and stability of black phosphorus-based oxygen evolution catalytic materials still need to be improved urgently. It is necessary to controllably construct the fine structure of black phosphorus-based materials to achieve the directional regulation of the adsorption energy of oxygen-containing active species, thereby enhancing the electrocatalytic oxygen evolution activity of black phosphorus-based catalysts.

[0005] In view of the above problems, the present invention document proposes a preparation method and application of an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst to solve the above-mentioned problems. Summary of the Invention

[0006] The present invention provides a preparation method and application of an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst, which solves the disadvantages of the prior art.

[0007] The present invention provides the following technical solutions:

[0008] A preparation method of an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst, the preparation method comprising the following steps:

[0009] S1. Dissolve tetrabutylammonium bromide and an iron salt in an acetonitrile solvent to obtain an electrolyte solution;

[0010] S2. Use a black phosphorus bulk as the cathode and a platinum sheet as the anode, immerse them in the electrolyte solution, and apply a voltage with a DC power supply for electrochemical intercalation and exfoliation;

[0011] S3. Ultrasonically treat, wash, and vacuum-dry the solution obtained in step S2 to obtain the iron-loaded electron-rich black phosphorus nanosheet electrocatalyst.

[0012] In a possible design, the mass concentration of tetrabutylammonium bromide in the electrolyte solution is 5-15 g / L.

[0013] In a possible design, the mass concentration of the iron salt in the electrolyte solution is 2-14 g / L.

[0014] In a possible design, the voltage for the electrochemical exfoliation process is 5-15 V, and the exfoliation time is 1-3 h.

[0015] In a possible design, the ultrasonic treatment time is 4-6 h, the vacuum drying temperature is 40-70 °C, and the vacuum drying time is 2-4 h.

[0016] An application of an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst as described above, the application of the iron-loaded electron-rich black phosphorus nanosheet electrocatalyst as a working electrode in an alkaline electrolyte for electrocatalytic water splitting oxygen evolution reaction.

[0017] It should be understood that the above general description and the following detailed description are only exemplary and do not limit the present invention.

[0018] The beneficial effects of the present invention are as follows:

[0019] (1) The iron-loaded electron-rich black phosphorus nanosheet electrocatalyst provided by the present invention has both high electrocatalytic activity and stability for water electrolysis oxygen evolution in alkaline electrolyte. For example, when the current density reaches 1000 mA cm -2 , the anodic overpotential is only about 379 mV, and it can maintain no obvious potential change for 24 h, providing the possibility for further improving the development and utilization of hydrogen energy;

[0020] (2) The iron-loaded electron-rich black phosphorus nanosheet electrocatalyst provided by the present invention has a two-dimensional layered structure, a high specific surface area, can effectively expose more reactive sites, enhance charge transport, and is beneficial to the progress of the electrocatalytic oxygen evolution reaction;

[0021] (3) The iron-loaded electron-rich black phosphorus nanosheet provided by the present invention increases the reactive sites and enhances the surface stability by regulating the electronic structure and surface properties of black phosphorus, and finally improves the catalytic activity and stability of the material for electrocatalytic oxygen evolution. Description of the Drawings

[0022] Figure 1 It is a scanning electron microscope image of the Fe / BP material prepared in Example 1 of the preparation method and application of an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst provided by an embodiment of the present invention;

[0023] Figure 2 It is a transmission electron microscope image of the Fe / BP material prepared in Example 1 of the preparation method and application of an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst provided by an embodiment of the present invention;

[0024] Figure 3 It is an X-ray diffraction pattern of the Fe / BP material prepared in Example 1 of the preparation method and application of an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst provided by an embodiment of the present invention;

[0025] Figure 4 It is a polarization curve graph of electrocatalytic oxygen evolution in the application example of the materials prepared in Examples 1-3 and Comparative Example 1 of the preparation method and application of an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst provided by an embodiment of the present invention;

[0026] Figure 5 It is a stability test graph of electrocatalytic oxygen evolution of the Fe / BP material prepared in Example 1 of the preparation method and application of an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst provided by an embodiment of the present invention. Detailed Embodiments

[0027] The embodiments of the present invention will be described below with reference to the accompanying drawings in the embodiments of the present invention.

[0028] In the description of the embodiments of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "connection" and "installation" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. In addition, "communication" can be a direct communication or an indirect communication through an intermediate medium. Among them, "fixing" means that they are connected to each other and the relative positional relationship after connection remains unchanged. The orientation terms mentioned in the embodiments of the present invention, such as "inside", "outside", "top", "bottom", etc., are only references to the direction of the attached drawings. Therefore, the orientation terms used are for better and clearer description and understanding of the embodiments of the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the embodiments of the present invention.

[0029] In the embodiments of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0030] In the embodiments of the present invention, "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0031] The reference to "one embodiment" or "some embodiments" etc. described in this specification means that in one or more embodiments of the present invention, specific features, structures or characteristics described in combination with this embodiment are included. Thus, the statements "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments" etc. that appear in different places in this specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0032] Embodiment 1

[0033] Referring to Figures 1-5 , a preparation method and application of an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst, comprising:

[0034] S1. Weigh 300 mg of tetrabutylammonium bromide solid particles and 324 mg of ferric chloride hexahydrate solid particles, dissolve them in 30 mL of acetonitrile solvent, and ultrasonically treat for 10 min at room temperature until completely dissolved to obtain a yellowish clear electrolyte solution.

[0035] S2. Use black phosphorus bulk as the cathode and a platinum sheet as the anode, immerse them into the electrolyte solution obtained in step S1, and apply a 10 V voltage using a DC power supply for 2 h for electrochemical intercalation and exfoliation.

[0036] S3. Ultrasonically treat the solution obtained in step S2 (100 W, 6 h), wash it multiple times with ethanol, and dry it in a vacuum oven at 50 °C for 4 h to obtain an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst (Fe / BP).

[0037] Figure 1 This is the scanning electron microscopy image of the iron-loaded electron-rich black phosphorus nanosheet electrocatalyst prepared in this example. Figure 2 This is the transmission electron microscopy image of the iron-loaded electron-rich black phosphorus nanosheet electrocatalyst prepared in this example. As can be seen from Figures 1-2 it, the obtained electrocatalyst has a two-dimensional nanosheet morphology. The X-ray diffraction pattern of the iron-loaded electron-rich black phosphorus nanosheet electrocatalyst prepared in this example is as shown in Figure 3 which, the peaks at 17.1°, 26.5°, 34.4° and 52.5° correspond to the (020), (021), (040) and (060) crystal planes of black phosphorus respectively.

[0038] Example 2

[0039] Follow the process of Example 1, with the difference that: the addition amount of ferric chloride hexahydrate when preparing the electrolyte in step S1 is 81 mg, and an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst is prepared.

[0040] Example 3

[0041] Follow the process of Example 1, with the difference that: the addition amount of ferric chloride hexahydrate when preparing the electrolyte in step S1 is 162 mg, and an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst is prepared.

[0042] Example 4

[0043] Follow the process of Example 1, with the difference that: the addition amount of ferric chloride hexahydrate when preparing the electrolyte in step S1 is 405 mg, and an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst is prepared.

[0044] Comparative Example 1

[0045] Follow the process of Example 1, with the difference that: ferric chloride hexahydrate is not added when preparing the electrolyte in step S1, and a black phosphorus nanosheet material (BP) is prepared.

[0046] Application Example

[0047] (1) Using a three - electrode system, the electrocatalysts prepared in Examples 1 - 4 or Comparative Example 1 were coated on nickel foam as the working electrode, the counter electrode was a carbon rod, the reference electrode was a Hg / HgO electrode, and the electrolyte was 1M KOH;

[0048] (2) Using a Shanghai Chenhua CHI 760E electrochemical workstation, nitrogen was bubbled through the electrolyte for 20 min before testing. Using the CV program, the test range was 0.924 - 1.924 V vs. reversible hydrogen electrode (RHE), and the scan rate was 100 mV s -1 , and it was cycled 20 times to make the catalytic material reach a stable state. Linear sweep voltammetry (LSV) tests were performed on the electrocatalysts of Examples 1 - 4 and Comparative Example 1. After CV activation, the program was switched to the LSV program. The test range was 0.924 - 2.425 V vs. RHE, the scan rate was 5 mV / s, and the overpotential was the difference between 1.23 V relative to the reversible hydrogen electrode and the measured potential at different current densities. The polarization curves of the electrocatalysts provided by Examples 1 - 4 and Comparative Example 1 for electrocatalytic oxygen evolution in 1M KOH solution are as Figure 4 shown. It can be seen from Figure 4 that in the alkaline electrolyte, the iron - loaded electron - rich black phosphorus nanosheet electrocatalyst (Fe / BP) prepared in Example 1 has good electrocatalytic hydrogen evolution activity. The current density of the electrocatalyst in Example 1 reached 1000 mA cm -2 with an overpotential of only 379 mV, and its catalytic performance is significantly better than that of the black phosphorus nanosheet material (BP).

[0049] The stability test was carried out on the electrode material prepared in Example 1

[0050] After CV activation, the program was switched to the ISTEP program, the current was set to 1 A, and the time was set to 86400 s. As Figure 5 shown, the potential of the iron - loaded electron - rich black phosphorus nanosheet electrocatalyst (Fe / BP) did not change much with time, demonstrating its excellent catalytic stability.

[0051] The working principle and usage process of this technical solution are as follows: Utilizing the migration of tetrabutylammonium ions under the electric field, intercalating into the interlayer of black phosphorus bulk and expanding it, followed by electrochemical exfoliation. At the same time, iron ions also migrate to black phosphorus due to the action of the electric field and undergo covalent coordination with phosphorus atoms to be in - situ loaded on black phosphorus nanosheets, finally obtaining the iron - loaded electron - rich black phosphorus nanosheet electrocatalyst.

[0052] The electrocatalyst has a two-dimensional nanosheet morphology, which can expose more catalytic active sites. Moreover, the abundant iron-phosphorus covalent interaction can effectively optimize the electronic structure of the black phosphorus material, resulting in an iron-loaded electron-rich black phosphorus material. This optimizes the adsorption energy of the catalytic active sites for the key oxygen-containing intermediates during the oxygen evolution process, ultimately enhancing the electrocatalytic oxygen evolution activity of the material.

[0053] The iron salt described in step S1 is a soluble salt, selected from ferric chloride, ferric nitrate, ferric sulfate and their hydrates, etc. Preferably, the iron salt is ferric chloride hexahydrate.

[0054] In step S1, the mass concentration of the iron salt is 2-14 g / L, and the mass concentration of tetrabutylammonium bromide is 5-15 g / L. If the concentration of the iron salt is too low, the iron loading amount is too small, and the regulation effect on the black phosphorus material is limited; if the concentration of the iron salt is too high, the iron sites will agglomerate, resulting in low utilization rate of the active sites. If the concentration of tetrabutylammonium bromide is too low, the black phosphorus bulk cannot be exfoliated, and if the concentration is too high, the exfoliation speed is too fast, which will cause the nanosheets to rupture.

[0055] In step S2, the voltage of the electrochemical exfoliation process is 5-15 V, and the exfoliation time is 1-3 h. Applying too low a voltage cannot exfoliate the black phosphorus bulk, and applying too high a voltage will cause the nanosheets to rupture.

[0056] In step S3, the ultrasonic treatment time is 4-6 h, the vacuum drying time is 2-4 h, and the drying temperature is 40-70 °C. Too high a drying temperature will cause the black phosphorus material to decompose or re-agglomerate, affecting the catalytic activity.

[0057] The present invention also provides an iron-loaded electron-rich black phosphorus nanosheet electrocatalyst (Fe / BP) prepared by the above preparation method. The iron-loaded electron-rich black phosphorus nanosheet electrocatalyst has a two-dimensional nanosheet layered structure.

[0058] The iron-loaded electron-rich black phosphorus nanosheet electrocatalyst provided by the present invention can be used as a catalytic material in the application of the oxygen evolution reaction at the anode of water electrolysis in an alkaline electrolyte.

[0059] In the oxygen evolution reaction at the anode of water electrolysis, a three-electrode system is adopted. Specifically, a Hg / HgO electrode is used as the reference electrode, a carbon rod is used as the counter electrode, the iron-loaded electron-rich black phosphorus nanosheet electrocatalyst provided by the present invention is used as the working electrode, and a 1 M KOH solution is used as the electrolyte.

[0060] Aiming at the problem of limited electrocatalytic activity of black phosphorus-based materials in the prior art, the present invention prepares the above-mentioned iron-loaded electron-rich black phosphorus nanosheet electrocatalyst through an electrochemical exfoliation and in-situ loading strategy, which can rationally design the fine structure of the black phosphorus material through iron-phosphorus covalent bonding, thereby effectively optimizing its electronic structure. The iron-loaded electron-rich black phosphorus nanosheet electrocatalyst provided by the present invention has abundant electron-rich phosphorus species, optimizes the adsorption energy of the material for oxygen-containing intermediate species, and finally improves the electrocatalytic oxygen evolution reaction activity of the material.

[0061] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention; without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for preparing an iron-supported electron-rich black phosphorus nanosheet electrocatalyst, characterized in that: The preparation method comprises the following steps: S1, dissolving tetrabutylammonium bromide and iron salt in acetonitrile solvent to obtain an electrolyte; S2, using the black phosphorus block as the cathode and the platinum sheet as the anode, immersing them in an electrolyte and applying voltage with a DC power supply for electrochemical intercalation and stripping; S3, subjecting the solution obtained in step S2 to ultrasonic treatment, washing, and vacuum drying to obtain the iron-supported electron-rich black phosphorus nanosheet electrocatalyst.

2. The preparation method and application of an iron-supported electron-rich black phosphorus nanosheet electrocatalyst according to claim 1, characterized in that: The mass concentration of tetrabutylammonium bromide in the electrolyte is 5 to 15 g / L.

3. The preparation method and application of an iron-supported electron-rich black phosphorus nanosheet electrocatalyst according to claim 1, characterized in that: The mass concentration of the iron salt in the electrolyte is 2-14 g / L.

4. The preparation method and application of an iron-supported electron-rich black phosphorus nanosheet electrocatalyst according to claim 1, characterized in that: The voltage of the electrochemical stripping process is 5 to 15 V, and the stripping time is 1 to 3 hours.

5. The preparation method and application of an iron-supported electron-rich black phosphorus nanosheet electrocatalyst according to claim 1, characterized in that: The ultrasonic treatment time is 4 to 6 hours, the vacuum drying temperature is 40 to 70° C., and the vacuum drying time is 2 to 4 hours.

6. An application of an iron-supported electron-rich black phosphorus nanosheet electrocatalyst as claimed in any one of claims 1 to 5, characterized in that: The iron-loaded electron-rich black phosphorus nanosheet electrocatalyst is used for electrocatalyzing water-oxygen separation reaction in alkaline electrolyte.

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