Nanorod-shaped Ni / Ni3S2 / VN electro-catalytic material as well as preparation method and application of nanorod-shaped Ni / Ni3S2 / VN electro-catalytic material

Abstract

The invention discloses a nanorod-shaped Ni / Ni3S2 / VN electro-catalytic material and a preparation method and application thereof.The preparation method comprises the steps that firstly, a nickel source is loaded on the surface of bacterial cellulose, and a Ni / Ni3S2 / VN electro-catalytic hydrogen evolution material with the nanorod-shaped morphology is prepared through a solid-phase sintering method; the bacterial cellulose is a pure natural biomass element, has no pollution to the environment, is green and environment-friendly, has a large number of carboxyl functional groups on the surface, can effectively complex free nickel ions in a solution as a template agent, and keeps good catalytic stability after being carbonized into carbon nanofibers, and Ni3S2 and VN are compounded, so that the catalytic performance of the carbon nanofibers is improved. According to the preparation method, a nanorod-shaped heterostructure is formed, part of Ni metal is reduced, all the components have a synergistic effect, the excellent electro-catalytic hydrogen evolution performance is shown in an alkaline environment, the preparation process is green, simple and convenient, and reaction conditions are easy to control.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials, relates to electrocatalytic materials, and specifically relates to a nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material, a preparation method thereof, and an application thereof. Background Art

[0002] The non-renewability and pollution problems of traditional fossil fuels no longer meet the concept of people's demand for clean and sustainable energy. The energy crisis and environmental pollution problems have become issues that the world faces together and needs to be solved hand in hand. As a reliable, green, sustainable, and rich natural resource, hydrogen has come into the view of many scholars and researchers. Hydrogen is the most abundant and cleanest element in nature. It has a higher calorific value than ordinary fuels and is almost three times that of gasoline under the same weight. As an ideal energy carrier, hydrogen can be applied to various fields such as communication, transportation, electricity, construction, and industry. People have studied the electrolytic water hydrogen production technology for more than 200 years. Compared with other hydrogen production methods, the electrolytic water technology has many advantages and is an ideal way to achieve green hydrogen production.

[0003] Although the electrolytic water hydrogen evolution technology has the advantages of being clean, pollution-free, and efficient, the electrocatalytic reaction itself has a relatively high energy barrier and slow kinetic properties, and a large amount of electric energy is required for the hydrogen evolution process. Currently, most commercial electrolytic water catalysts are noble metal-based catalysts such as Pt / C, IrO2, and RuO2. However, for large-scale applications, the scarcity of these catalysts greatly increases the cost and has a negative impact on the environment during the mining and refining processes. The key to reducing its energy consumption is to develop highly efficient electrocatalytic materials for the electrolytic water hydrogen evolution reaction and improve the kinetic properties. For this reason, researchers are committed to exploring cost-effective, abundant, efficient, and stable non-noble metal-based catalyst materials to replace noble metal catalysts.

[0004] Generally speaking, an excellent electrolyzed water catalyst should possess high internal electrical conductivity, abundant surface active sites, and high economic benefits. Due to their unique structural characteristics, transition metal sulfides (TMS) have attracted great interest as potential electrocatalytic materials. In the field of non-noble metal HER electrocatalytic materials, nickel-based catalysts have shown great potential to replace noble metal-based catalysts due to their unique physical and chemical properties, excellent catalytic performance, high abundance, low cost, high conductivity, etc. As a member of the transition metal sulfide family, nickel sulfide (Ni2S3) has become one of the efficient electrocatalytic materials in an alkaline electrolyte environment due to its excellent conductivity and stability. Sulfides generally exhibit a narrower bandgap than phosphides because sulfur (S) atoms have a larger atomic radius and weaker electronegativity than phosphorus (P) atoms, resulting in higher electrical conductivity of the electrocatalytic material. However, the catalytic performance of nickel sulfide (Ni2S3) as an electrolyzed water hydrogen evolution catalyst still has much room for improvement compared to noble metal-based catalysts. The binding energy between Ni and H is relatively large, and the generated H2 molecules are difficult to desorb from the Ni surface, leading to slow HER kinetics during the reaction process. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material, its preparation method and application. The preparation process is green and simple, has excellent alkaline electrocatalytic hydrogen evolution performance, and has good catalytic stability at the same time.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions to achieve:

[0007] A preparation method of a nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material, comprising the following steps:

[0008] Step 1: Take 0.1 - 0.5 mmol of nickel sulfate, 0.5 - 1.0 g of bacterial cellulose, 0.05 - 0.01 mmol of polytetrafluoroethylene, add them to 150 - 300 ml of deionized water, stir at 60 °C for 6 - 12 hours, centrifuge to separate the solid, wash and freeze-dry to obtain a powder;

[0009] Step 2: Take 200 - 500 mg of the powder prepared in Step 1, 0.01 - 0.05 mmol of sodium metavanadate, 0.4 - 1.2 mmol of glucose, 0.1 - 0.6 mmol of sodium thiosulfate, grind and mix them evenly, place them in a magnetic boat, transfer them to a tubular furnace, and under an argon atmosphere, heat from room temperature to 700 - 900 °C at a heating rate of 5 - 10 °C / min, keep warm for 2 - 4 h, and then naturally cool to room temperature. Grind the calcined powder in a mortar until there is no particle feeling to obtain the Ni / Ni3S2 / VN electrocatalytic material.

[0010] The present invention also has the following technical features:

[0011] Preferably, the molecular weight range of the polytetrafluoroethylene described in step one is 2×10 6 ~6×10 6 g / mol.

[0012] Preferably, the centrifugation speed described in step one is 6000 - 10000 rpm.

[0013] Preferably, the washing described in step one is to wash alternately with deionized water and ethanol for 3 - 5 times.

[0014] Preferably, the grinding described in step two is to grind with a mortar for 30 min.

[0015] The present invention also protects a nanorod - shaped Ni / Ni3S2 / VN electrocatalytic material prepared by the method as described above and its application in hydrogen production by electrolyzing water.

[0016] Compared with the prior art, the present invention has the following technical effects:

[0017] For the Ni / Ni3S2 / VN electrocatalytic hydrogen evolution material prepared by the present invention, Ni3S2 and VN are compounded to form a heterostructure, and multiple heterointerfaces are integrated in the material. The inherent electronic structure of Ni3S2 is optimized by the unique interfacial coupling synergy, the distribution of the electron cloud of the active center is changed, the dissociation and desorption of H2 molecules are promoted, and its catalytic performance is improved; on the other hand, the material prepared by the present invention presents a microstructure composed of nanorods. The highly open hierarchical nanowire network structure with high - activity sites exposed can greatly increase the close - contact specific surface area between the catalyst and the electrolyte, improve the charge - transfer efficiency of the material, and more easily release the evolved gas during the HER catalytic process; secondly, under the action of the carbon source, part of the Ni metal is reduced in the present invention. From the perspective of the electronic structure level, the Ni metal single - atom can optimize the surface structure of the electrocatalytic material, not only change the morphology of the catalyst, but also further optimize the electronic structure of Ni3S2, further affecting the binding energy of hydrogen / oxygen intermediates during the water - splitting process. The two - component synergistic effect shows excellent electrocatalytic hydrogen evolution performance in an alkaline environment.

[0018] The preparation process of the present invention is green and simple, the reaction conditions are easy to control. Bacterial cellulose, as a pure natural biotin, is environmentally friendly and pollution - free. It has a large number of carboxyl functional groups on its surface. As a template agent, it can effectively complex the free nickel ions in the solution, and maintain its nanorod - shaped structure after carbonization into carbon nanofibers, which can enhance the conductivity of the catalytic material and has good catalytic stability. Description of the Drawings

[0019] Figure 1XRD pattern of the Ni / Ni3S2 / VN electrocatalytic material prepared in Example 1;

[0020] Figure 2 Linear sweep voltammetry test curve (LSV) of the Ni / Ni3S2 / VN electrocatalytic material prepared in Example 1 in a traditional three-electrode system;

[0021] Figure 3 Scanning electron microscope (SEM) image of the Ni / Ni3S2 / VN electrocatalytic material prepared in Example 1. Detailed implementation manners

[0022] The following further elaborates on the specific content of the present invention in conjunction with examples.

[0023] In the following examples, the molecular weight range of the polytetrafluoroethylene used is 2×10 6 ~6×10 6 g / mol

[0024] Example 1

[0025] This example provides a method for preparing a nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material, including the following steps:

[0026] Step 1: Take 0.1 mmol of nickel sulfate, 1.0 g of bacterial cellulose, 0.05 mmol of polytetrafluoroethylene, add them to 300 ml of deionized water, stir at 60 °C for 12 hours, perform solid-liquid separation on solution A using a centrifugal device, set the rotation speed to 10000 rpm, separate the solid, wash it 3 times alternately with deionized water and ethanol, and obtain a powder after freeze-drying;

[0027] Step 2: Take 200 mg of the powder prepared in Step 1, 0.05 mmol of sodium metavanadate, 0.7 mmol of glucose, 0.3 mmol of sodium thiosulfate, mix them evenly by grinding in a mortar for 30 min, place them in a magnetic boat, transfer them to a tubular furnace, under an argon atmosphere, heat from room temperature to 900 °C at a heating rate of 10 °C / min, hold for 2 h, and then cool naturally to room temperature. Grind the calcined powder in a mortar for 30 min until there is no particle feeling to obtain the Ni / Ni3S2 / VN electrocatalytic material.

[0028] Figure 1 XRD pattern of the Ni / Ni3S2 / VN electrocatalytic material prepared in Example 1; as Figure 1As shown, the characteristic peaks at 21.755°, 31.101°, 37.795°, 38.276°, 44.349°, 49.725°, 50.112°, 54.612°, 55.155°, 55.335°, 64.191°, 64.848°, 68.326°, 68.963°, 68.963°, 69.280°, 73.044°, 73.509°, 76.963°, 77.571°, 77.874° correspond to the (1 0 0), (-1 1 0), (1 1 1), (1 -11), (2 0 0), (2 1 0), (2 -1 0), (2 1 1), (2 -1 1), (1 -2 1), (2 2 0), (2 -2 0), (2 21), (3 0 0), (2 -2 1), (3 1 0), (3 -1 0), (3 1 1), (3 -11), (1 -3 1) crystal planes of Ni3S2 (PDF#85-1802); the characteristic peaks at 44.604°, 51.977°, 76.588° correspond to the (1 1 1), (2 0 0), (2 2 0) crystal planes of Ni (PDF#70-0989); the peaks located at 37.6°, 43.7°, 63.5° and 76.2° are attributed to the (1 1 1), (2 00), (2 2 0) and (3 1 1) crystal planes of VN (JCPDS card number 35-0768); indicating the successful preparation of the Ni / Ni3S2 / VN electrocatalytic material.

[0029] Figure 2 Figure (LSV) of the linear voltammetry scan test for the Ni / Ni3S2 / VN electrocatalytic material prepared in Example 1 in a traditional three-electrode system; 1M KOH solution serves as the buffer, and the curve is corrected by 85% of IR to eliminate the influence of solution resistance on the catalytic performance test. From Figure 2 it can be read that to achieve a current density of 10 mA / cm 2 (η10), 100 mA / cm 2 (η100), the overpotentials for electrocatalytic water splitting only require 145 mV and 390 mV respectively.

[0030] Figure 3 Figure of the scanning electron microscope (SEM) of the Ni / Ni3S2 / VN electrocatalytic material prepared in Example 1. From Figure 3 it can be seen that the material is composed of stacked nanorods, which greatly increases the specific surface area of the sample, can significantly enhance the hydrogen evolution reaction efficiency, and plays a promoting role in reducing the overpotential of electrocatalytic water splitting for hydrogen evolution.

[0031] Example 2

[0032] This embodiment provides a method for preparing a nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material, which includes the following steps:

[0033] Step 1: Take 0.3 mmol of nickel sulfate, 0.8 g of bacterial cellulose, and 0.08 mmol of polytetrafluoroethylene, add them to 200 ml of deionized water, stir at 60 °C for 8 hours, use a centrifuge to perform solid-liquid separation on solution A, set the rotation speed to 7000 rpm, separate the solid, wash it 5 times alternately with deionized water and ethanol, and freeze-dry to obtain a powder.

[0034] Step 2: Take 500 mg of the powder prepared in Step 1, 0.03 mmol of sodium metavanadate, 0.4 mmol of glucose, and 0.1 mmol of sodium thiosulfate, grind them evenly with a mortar for 30 min, place them in a magnetic boat, transfer them to a tube furnace, under an argon atmosphere, heat from room temperature to 800 °C at a heating rate of 5 °C / min, hold for 3 h, and then naturally cool to room temperature. Grind the calcined powder in a mortar for 30 min until there is no granular feeling to obtain the Ni / Ni3S2 / VN electrocatalytic material.

[0035] Example 3

[0036] This embodiment provides a method for preparing a nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material, which includes the following steps:

[0037] Step 1: Take 0.5 mmol of nickel sulfate, 0.5 g of bacterial cellulose, and 0.01 mmol of polytetrafluoroethylene, add them to 150 ml of deionized water, stir at 60 °C for 6 hours, use a centrifuge to perform solid-liquid separation on solution A, set the rotation speed to 8000 rpm, separate the solid, wash it 4 times alternately with deionized water and ethanol, and freeze-dry to obtain a powder.

[0038] Step 2: Take 300 mg of the powder prepared in Step 1, 0.01 mmol of sodium metavanadate, 1.2 mmol of glucose, and 0.6 mmol of sodium thiosulfate, grind them evenly with a mortar for 30 min, place them in a magnetic boat, transfer them to a tube furnace, under an argon atmosphere, heat from room temperature to 700 °C at a heating rate of 8 °C / min, hold for 4 h, and then naturally cool to room temperature. Grind the calcined powder in a mortar for 30 min until there is no granular feeling to obtain the Ni / Ni3S2 / VN electrocatalytic material.

[0039] Those of ordinary skill in the art will realize that the embodiments described herein are provided to assist the reader in understanding the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations that do not depart from the essence of the present invention based on these technical revelations disclosed in the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A preparation method of a nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material, characterized in that, It includes the following steps: Step 1: Take 0.1 - 0.5 mmol of nickel sulfate, 0.5 - 1.0 g of bacterial cellulose, and 0.05 - 0.01 mmol of polytetrafluoroethylene, add them to 150 - 300 ml of deionized water, stir at 60 °C for 6 - 12 hours, centrifuge to separate the solid, wash and freeze-dry to obtain a powder; Step 2: Take 200 - 500 mg of the powder prepared in Step 1, 0.01 - 0.05 mmol of sodium metavanadate, 0.4 - 1.2 mmol of glucose, and 0.1 - 0.6 mmol of sodium thiosulfate, grind and mix them evenly, place them in a magnetic boat, transfer to a tubular furnace, under an argon atmosphere, heat from room temperature to 700 - 900 °C at a heating rate of 5 - 10 °C / min, hold for 2 - 4 h, and then cool naturally to room temperature. Grind the calcined powder in a mortar until there is no particle feeling to obtain the Ni / Ni3S2 / VN electrocatalytic material.

2. The preparation method of the nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material according to claim 1, characterized in that, The molecular weight range of the polytetrafluoroethylene described in Step 1 is 2×10 6 ~6×10 6 g / mol.

3. The preparation method of the nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material according to claim 1, characterized in that, The centrifugation speed in Step 1 is 6000 - 10000 rpm.

4. The preparation method of the nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material according to claim 1, characterized in that, The washing in Step 1 is to wash alternately with deionized water and ethanol for 3 - 5 times.

5. The preparation method of the nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material according to claim 1, characterized in that, The grinding in Step 2 is to grind with a mortar for 30 min.

6. A nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material prepared by the method according to any one of claims 1 to 5.

7. An application of the nanorod-shaped Ni / Ni3S2 / VN electrocatalytic material according to claim 6 in hydrogen production by electrolyzing water.

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