Cobalt-doped nickel ditelluride single crystal with high electro-catalytic hydrogen evolution performance and preparation method of cobalt-doped nickel ditelluride single crystal

Abstract

The invention relates to a cobalt-doped nickel ditelluride single crystal with high electro-catalytic hydrogen evolution performance and a preparation method thereof, and belongs to the technical field of single crystal growth. The chemical general formula of the single crystal is Ni1-xCoxTe2, wherein x is more than or equal to 0 and less than or equal to 1. The preparation method comprises the following steps: mixing high-purity nickel powder, cobalt powder and tellurium powder according to a stoichiometric ratio, sealing in a quartz tube, carrying out heat preservation for 24 hours at 600 DEG C under a vacuum condition, heating to 1000 DEG C, carrying out heat preservation for 48 hours, carrying out solid-phase reaction, slowly cooling to 500 DEG C at a rate of 1.5 DEG C / h, and carrying out water quenching to obtain the cobalt-doped nickel ditelluride single crystal with a large size and a layered structure. The method is simple in process and good in repeatability, and the obtained single crystal is high in quality and suitable for scientific research of materials.

Description

Technical Field

[0001] This invention relates to the field of single crystal growth technology, specifically to a cobalt-doped nickel ditelluride single crystal with high electrocatalytic hydrogen evolution performance and its preparation method. This method achieves controllable preparation of large-size, high-quality single crystals by optimizing the solid-state reaction process. Background Technology

[0002] Single crystals of transition metal dichalcogenides are of significant value in fundamental research due to their layered structure and tunable crystal properties. Nickel ditelluride (NiTe2), a typical layered material, is typically prepared as a single crystal using methods such as chemical vapor deposition (CVD), but these methods suffer from drawbacks such as expensive equipment, complex processes, and small crystal sizes. While solid-state reaction methods offer simpler equipment, they still present challenges in controlling the growth of cobalt-doped NiTe2 single crystals, leading to issues such as uneven crystal size and poor crystal quality. Therefore, developing a simple and highly controllable method for preparing cobalt-doped nickel ditelluride single crystals is of great importance. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a cobalt-doped nickel ditelluride single crystal with high electrocatalytic hydrogen evolution performance and its preparation method. This method achieves controllable preparation of high-quality single crystals by optimizing the raw material ratio, heat treatment process, and cooling process. The technical solution of this invention is as follows: A method for preparing cobalt-doped nickel ditelluride single crystals, comprising the following steps: Step 1: Raw material mixing: Mix high-purity (≥99.99%) nickel powder, cobalt powder and tellurium powder according to the stoichiometric ratio, and grind for 10 minutes until uniform; Step 2: Vacuum sealing: Seal the mixture in a quartz tube and evacuate to a high vacuum (10). -3 Up to 10 -4 Pa); Step 3: Heat treatment: A two-step heat treatment is adopted, first holding at 600℃ for 24 hours, and then raising the temperature to 1000℃ and holding for 48 hours; Step 4: Cooling and crystallization: Slowly cool to 500℃ at a rate of 1.5℃ / h, then quench in water or air cool to room temperature to obtain single crystals.

[0004] The beneficial effects of this invention are: (1) The preparation method is simple, the equipment requirements are low, and it is suitable for large-scale production; (2) By optimizing the heat treatment process, large-size, high-quality single crystals can be obtained. Attached Figure Description

[0005] Figure 1 This is an optical photograph of a cobalt-doped nickel ditelluride single crystal prepared according to an embodiment of the present invention, showing its layered structure and metallic luster.

[0006] Figure 2 The X-ray diffraction pattern of the single crystal in this embodiment of the invention confirms its high crystallinity.

[0007] Figure 3 This is the hydrogen evolution polarization curve of a single crystal under acidic conditions according to an embodiment of the present invention.

[0008] Figure 4 This is the hydrogen evolution polarization curve of a single crystal under alkaline conditions according to an embodiment of the present invention. Detailed Implementation

[0009] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0010] KF1100 muffle furnace: purchased from Boyuntong Company.

[0011] X-ray diffractometer: purchased from Bruker Corporation, USA.

[0012] Electrochemical workstation: purchased from CHI Chemicals, USA.

[0013] raw material: Nickel powder: purchased from Zhongnuo New Materials Co., Ltd., purity 99.99%.

[0014] Cobalt powder: purchased from Zhongnuo New Materials Co., Ltd., with a purity of 99.99%.

[0015] Tellurium powder: purchased from Zhongnuo New Materials Co., Ltd., purity 99.99%. Preparation of Ni with high electrocatalytic hydrogen evolution performance. 0.6 Co 0.4 Te2 single crystal Example 1:

[0016] Step 1: Raw material mixing: Weigh 1.2g of Ni powder (99.99% purity), 0.8g of Co powder and 8.7g of Te powder, and grind and mix them in an alumina mortar for 10 minutes; Step 2: Vacuum sealing: Fill the mixture into a quartz tube and evacuate to 3×10⁻⁶. -4 After sealing (Pa); Step 3: Heat treatment: The quartz tube is placed in a high-temperature furnace and heated to 600℃ at a rate of 5℃ / min, and held at that temperature for 24 hours; then heated to 1000℃ at the same rate and held at that temperature for 48 hours. Step 4: Cooling and crystallization: Cool to 500°C at a rate of 1.5°C / h, remove and water-cool to room temperature to obtain Ni. 0.6 Co 0.4 Te2 single crystal.

[0017] The obtained single crystals exhibit a silvery-gray metallic luster and a clear layered structure, such as Figure 1 As shown. X-ray diffraction tests revealed sharp diffraction peaks, indicating high crystallinity, such as... Figure 2 As shown. The electrocatalytic performance of the obtained single crystal was tested: Under acidic conditions (0.5 MH₂SO₄), the single crystal at 10 mA cm⁻¹... -2 The hydrogen evolution overpotential at the current density is 419 mV ( Figure 3 Under alkaline conditions (1 MKOH), the hydrogen evolution overpotential is 362 mV. Figure 4 Stability tests showed that after 40 hours of continuous testing, the single crystal still maintained more than 90% of its catalytic activity.

[0018] Example 2: Step 1: Raw material mixing: Weigh 1.0g of Ni powder (99.99% purity), 1.0g of Co powder, and 9g of Te powder, and grind and mix them in an alumina mortar for 10 minutes; Step 2: Vacuum sealing: Fill the mixture into a quartz tube and evacuate to 3×10⁻⁶. -4 After sealing (Pa); Step 3: Heat treatment: The quartz tube is placed in a high-temperature furnace and heated to 600℃ at a rate of 5℃ / min, and held at that temperature for 24 hours; then heated to 1000℃ at the same rate and held at that temperature for 48 hours. Step 4: Cooling and crystallization: Cool to 500°C at a rate of 1.5°C / h, remove and water-cool to room temperature to obtain Ni. 0.5 Co 0.5 Te2 single crystal.

[0019] Step 1: Raw material mixing: Weigh 0.8g of Ni powder (99.99% purity), 1.2g of Co powder, and 10g of Te powder, and grind and mix them in an alumina mortar for 10 minutes; Step 2: Vacuum sealing: Fill the mixture into a quartz tube and evacuate to 3×10⁻⁶. -4 After sealing (Pa); Step 3: Heat treatment: The quartz tube is placed in a high-temperature furnace and heated to 600℃ at a rate of 5℃ / min, and held at that temperature for 24 hours; then heated to 1000℃ at the same rate and held at that temperature for 48 hours. Step 4: Cooling and crystallization: Cool to 500°C at a rate of 1.5°C / h, remove and water-cool to room temperature to obtain Ni. 0.4 Co 0.6 Te2 single crystal.

[0020] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A cobalt-doped nickel ditelluride single crystal with high electrocatalytic hydrogen evolution performance and its preparation method, characterized by the following steps: include: Step 1, Raw material mixing: Nickel powder, cobalt powder and tellurium powder are mixed in stoichiometric ratio to obtain a mixture; Step 2, Vacuum sealing: Seal the mixture in a quartz tube and use a mechanical pump to create a vacuum; Step 3, Heat treatment: The vacuum-sealed quartz tube is subjected to heating heat treatment and heat preservation heat treatment. Step 4, Cooling and Crystallization: Slowly cool to the preset temperature and then rapidly cool to room temperature to obtain cobalt-doped nickel ditelluride single crystals.

2. The cobalt-doped nickel ditelluride single crystal with high electrocatalytic hydrogen evolution performance and its preparation method according to claim 1, characterized in that: The general chemical formula of the single crystal in step 1 is Ni. 1-x Co x Te2 refers to the stoichiometric ratio of the raw material mixture, specifically the molar ratio of nickel powder, cobalt powder, and tellurium powder as (1-x):x:2, where the value of x ranges from 0 to x and from 1 to 0.

3. The cobalt-doped nickel ditelluride single crystal with high electrocatalytic hydrogen evolution performance and its preparation method according to claim 1, characterized in that: In step 2, the vacuum level drawn by the mechanical pump is 10. -3 Up to 10 -4 Pa.

4. The cobalt-doped nickel ditelluride single crystal with high electrocatalytic hydrogen evolution performance and its preparation method according to claim 1, characterized in that: In step 3, the temperature for the heat treatment is 600℃-1000℃, and the holding time is 24 hours-48 hours.

5. The cobalt-doped nickel ditelluride single crystal with high electrocatalytic hydrogen evolution performance and its preparation method according to claim 1, characterized in that: In step 4, the slow cooling rate for cooling crystallization is 1-2℃ / h. After cooling to 500℃, it is rapidly cooled to room temperature by quenching.

6. The cobalt-doped nickel ditelluride single crystal with high electrocatalytic hydrogen evolution performance and its preparation method according to claim 1, characterized in that: The purity of the nickel powder, cobalt powder, and tellurium powder is not less than 99.99%.

7. The cobalt-doped nickel ditelluride single crystal with high electrocatalytic hydrogen evolution performance and its preparation method according to claim 1, characterized in that: The cobalt-doped nickel ditelluride single crystal has a size of 80-100 mm², a thickness of 100-150 μm, and a layered structure.

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