Yarn ball-shaped hydrogen evolution catalyst material and preparation method

Abstract

This invention belongs to the field of material preparation technology and specifically discloses a yarn-shaped hydrogen evolution catalyst. The catalyst is a yarn-shaped nanosphere structure with a composition of MS-WS2, where M is Ni, Fe, or Co. The yarn-shaped nanospheres have raised long ridges on the outside of the yarn, and multiple interconnected nanosheets are connected between the long ridges and the yarn. The yarn-shaped nanospheres prepared by this scheme can be used to catalyze hydrogen evolution, solving the problem of small specific surface area and low catalytic efficiency of nanospheres in the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of material preparation, and specifically discloses a method for preparing a yarn ball-shaped hydrogen evolution catalyst. Background Art

[0002] In today's society, with the advancement of science and technology and the rapid development of the world economy, people's demand for energy is increasing, which has prompted researchers to study new energy more urgently. Hydrogen produced by electrocatalytic water decomposition is a green and pollution-free energy source, which is expected to help people solve the energy crisis and environmental problems. At present, due to the high price and scarcity of Pt-based catalysts, the development of cheap, efficient and Pt-replaceable hydrogen evolution catalysts is urgent. Transition-metal chalcogenides (TMCs), such as WS2 and MoS2, are considered to be promising hydrogen evolution catalysts due to their low cost, high earth abundance and good stability. Although WS2 has many advantages, both theoretical and experimental results show that only its edge sites have hydrogen evolution catalytic activity, while the larger basal plane is inert. In order to improve the hydrogen evolution performance of WS2, doping with transition metal Ni, Fe or Co is a conventional means of regulating and modifying the catalyst morphology and structure.

[0003] In the prior art, after doping the transition metal Ni in MoS2 or WS2 nanospheres, Co9S8-Ni3S2@WS2 (XingQian et al., Applied Surface Science 573 (2022) 151606) or MoS2 / NiS core-shell nanospheres (Xien Liu et al., Small, 2019, 15, 1803639) are often formed. It is difficult to form NiS phase and NiS-MoS2 uniform structure. This method requires ionic liquid-assisted growth (Xien Liu et al., Small, 2019, 15, 1803639) and high temperature and a long growth cycle when growing NiS phase, which is complicated to operate. Moreover, the surface of these nanospheres is assembled only by a single layer of nanosheets, and the edge of the exposed nanosheet per unit volume is still limited, which reduces the catalytic efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a yarn ball-shaped hydrogen evolution catalyst, which solves the problem in the prior art that the surface area of ​​nanospheres is small, thereby reducing the catalytic efficiency.

[0005] In order to achieve the above-mentioned purpose, the technical solution of the present invention is as follows: a yarn ball-shaped hydrogen evolution catalyst, the catalyst is a yarn ball-shaped structure with a nanosphere morphology, the catalyst is MS-WS2, M is Ni, the outer side of the wire on the yarn ball-shaped structure has a raised long edge along the length direction, and a plurality of interconnected nanosheets are connected between the long edge and the wire.

[0006] Furthermore, the diameter of the MS-WS2 nanospheres is 0.5-2 μm, the length of the nanosheets is 50-100 nm, and the thickness is 5-20 nm.

[0007] Furthermore, the catalyst can be used for catalytic hydrogen evolution reaction in acidic and alkaline media.

[0008] Furthermore, a method for preparing a yarn ball-shaped hydrogen evolution catalyst comprises the following steps:

[0009] (1) Hydrothermal synthesis reaction: Place the reagents containing W source, S source and nickel acetate into a hydrothermal reactor, dissolve the reagents in water, and heat the reactor to 120-220°C for reaction for 1-8 hours;

[0010] (2) filtering, washing, and drying the solid-liquid mixture obtained after the reaction in step (1) to obtain a NiWS precursor;

[0011] (3) Reducing atmosphere annealing: The NiWS precursor material in step (1) is heated to 100-400°C in a reducing atmosphere of Ar / H2 mixed gas and kept warm for 10-300 minutes to obtain NiS-WS2 nanospheres.

[0012] Furthermore, in step (1), the molar mass ratio of the raw materials W source, S source, and nickel acetate is (1-7): (0.5-1.5): 2; the W source is ammonium metatungstate, and the S source is thioacetamide.

[0013] Furthermore, the heating rate of the hydrothermal synthesis reaction in step (1) is 2-5°C / min, the heating rate of the reducing atmosphere annealing reaction is 2-5°C / min, and the reaction time is 0.5-3h.

[0014] Furthermore, during the reducing atmosphere annealing treatment, the volume fraction of hydrogen in step (3) is 1%-5%, and the flow rate of the Ar / H2 mixed gas is 5-40 mL / min.

[0015] The working principle and beneficial effects of this technical solution are:

[0016] (1) The NiS-WS2 hydrogen evolution catalyst provided by the present invention has a wool ball-like structure. The raised prismatic stripes on the nanospheres provide growth attachment points for the growth of nanosheets. After the nanosheets grow on the ridges, more surfaces and edges are exposed on the nanospheres of the same volume. When the material of the present invention is used to catalyze the hydrogen evolution reaction, the nanosheets on the nanosphere body and the nanosheets grown on the raised prismatic structure can serve as active sites for the hydrogen evolution catalytic reaction, greatly improving the catalytic activity of the hydrogen evolution catalyst.

[0017] (2) The yarn-shaped hydrogen evolution catalyst provided by the present invention has a uniform morphology and controllable size. The diameter of the nanospheres can be adjusted between 0.5 and 2 μm. The size of the nanosheets that make up the nanospheres is 50-100 nm and the thickness is 5-20 nm. The nanospheres in this solution are smaller than the nanospheres used in the prior art, and the number of nanosheets that make up the nanospheres is also greater than that of traditional nanospheres. This means that for nanospheres of the same mass, the nanospheres in this solution have a larger specific surface area and more edges, and thus have more catalytic active sites.

[0018] (3) The hydrogen evolution catalyst of the present invention forms raised prismatic stripes during the preparation of nanospheres to provide attachment points for the growth of nanosheets. After the nanosheets grow on the ridges, more surfaces and edges are exposed on the nanospheres of the same volume.

[0019] (4) Compared with the traditional method, this scheme does not require a morphology modification step or a sulfurization step. This technology uses a one-step hydrothermal method to form a wool ball structure. The elements of the ball structure are evenly distributed, which provides an effective new method for the preparation of a uniformly distributed two-phase structure hydrogen evolution catalyst.

[0020] (5) This solution addresses the low catalytic activity of transition metal chalcogenides for hydrogen evolution, as well as the complex operations, long reaction times, and high reaction temperatures involved in the preparation of the NiS phase. Transition metal chalcogenide nanospheres prepared by conventional hydrothermal synthesis are mostly assembled from nanosheets, with only the limited exposed nanosheet edges exhibiting catalytic activity. The present invention provides a method for increasing the number of nanosphere edges, thereby significantly increasing the catalytic activity of the nanospheres. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the SEM image of the NiS-WS2 nanospheres obtained in Example 1 of the present invention;

[0022] Figure 2 This is the EDX spectrum of the NiS-WS2 nanospheres obtained in Example 1 of the present invention;

[0023] Figure 3 This is the element distribution mapping of the NiS-WS2 nanospheres obtained in Example 1 of the present invention;

[0024] Figure 4 is the XRD pattern of NiS-WS2 nanospheres obtained in Example 1 of the present invention;

[0025] Figure 5 This is the XPS spectrum of the NiS-WS2 nanospheres obtained in Example 1 of the present invention;

[0026] Figure 6 This is a hydrogen evolution spectrum of NiS-WS2 nanospheres obtained in Example 1 of the present invention in an acidic solution;

[0027] Figure 7 This is a hydrogen evolution spectrum of NiS-WS2 nanospheres obtained in Example 1 of the present invention in an alkaline solution;

[0028] Figure 8 This is the SEM image of the NiS-WS2 nanospheres obtained in Example 2 of the present invention;

[0029] Figure 9 This is the SEM image of the NiS-WS2 nanospheres obtained in Example 3 of the present invention;

[0030] Figure 10 This is the SEM image of the NiS-WS2 nanospheres obtained in Example 4 of the present invention.

[0031] The specific implementation process is as follows:

[0032] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of the present invention. Any product identical or similar to the present invention, derived by anyone under the guidance of the present invention or by combining the features of the present invention with those of other prior arts, falls within the scope of protection of the present invention. Furthermore, the technical features involved in the different embodiments of the present invention described below may be combined with one another as long as they do not conflict with each other.

[0033] Description of the accompanying figures: long edge 1, nanosheet 2.

[0034] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0035] Example 1

[0036] This embodiment provides a method for preparing a yarn-shaped NiS-WS2 hydrogen evolution catalyst, which is obtained by the following preparation steps:

[0037] (1) Prepare the precursor solution by accurately weighing 4 g of thioacetamide, 0.25 g of ammonium metatungstate, 1.4 g of oxalic acid, and 0.45 g of nickel acetate, then add 30 ml of distilled water and stir in a 60 ° C water bath for 2 h until completely dissolved;

[0038] (2) Add 30 ml of the prepared precursor solution to the reactor, tighten the seal, place the reactor in a constant temperature drying oven, set the temperature to 200 ° C and keep it warm for 7 hours. After the temperature in the constant temperature drying oven drops to room temperature, centrifuge to separate the solid product, wash it with deionized water and anhydrous ethanol several times by centrifugation, and dry it at room temperature to obtain a Ni-doped sample;

[0039] (3) The dried sample was placed in a quartz boat and annealed in an Ar / H2 mixed gas with a hydrogen content of 5% at a flow rate of 40 mL / min. The sample was kept at 400°C for 3 h and then cooled naturally to room temperature to obtain a wooly ball-shaped NiS-WS2 product.

[0040] Example 2

[0041] This embodiment provides a method for preparing a yarn-shaped NiS-WS2 hydrogen evolution catalyst, which is obtained by the following preparation steps:

[0042] (1) Prepare the precursor solution by accurately weighing 4 g of thioacetamide, 0.25 g of ammonium metatungstate, 1.4 g of oxalic acid, and 0.15 g of nickel acetate, then add 30 ml of distilled water and stir in a 60 ° C water bath for 2 h until completely dissolved.

[0043] (2) Add 30 ml of the prepared precursor solution to the reactor, tighten the seal, place the reactor in a constant temperature drying oven, set the temperature to 200 ° C and keep it warm for 7 hours. After the temperature in the constant temperature drying oven drops to room temperature, centrifuge to separate the solid product, wash it with deionized water and anhydrous ethanol several times by centrifugation, and dry it at room temperature to obtain a Ni-doped sample;

[0044] (3) The dried sample was placed in a quartz boat and annealed in an Ar / H2 mixed gas with a hydrogen content of 5% at a flow rate of 40 mL / min. The sample was kept at 400°C for 3 h and then cooled naturally to room temperature to obtain a wooly ball-shaped NiS-WS2 product.

[0045] Example 3

[0046] This embodiment provides a method for preparing a yarn-shaped NiS-WS2 hydrogen evolution catalyst, which is obtained by the following preparation steps:

[0047] (1) Prepare the precursor solution by accurately weighing 4 g of thioacetamide, 0.25 g of ammonium metatungstate, 1.4 g of oxalic acid, and 0.3 g of nickel acetate, then add 30 ml of distilled water and stir in a 60 ° C water bath for 2 h until completely dissolved;

[0048] (2) Add 30 ml of the prepared precursor solution to the reactor, tighten the seal, place the reactor in a constant temperature drying oven, set the temperature to 200 ° C and keep it warm for 7 hours. After the temperature in the constant temperature drying oven drops to room temperature, centrifuge to separate the solid product, wash it with deionized water and anhydrous ethanol several times by centrifugation, and dry it at room temperature to obtain a Ni-doped sample;

[0049] (3) The dried sample was placed in a quartz boat and annealed in an Ar / H2 mixed gas with a hydrogen content of 5% at a flow rate of 40 mL / min. The sample was kept at 400°C for 3 h and then cooled naturally to room temperature to obtain a wooly ball-shaped NiS-WS2 product.

[0050] Example 4

[0051] This embodiment provides a method for preparing a yarn-shaped NiS-WS2 hydrogen evolution catalyst, which is obtained by the following preparation steps:

[0052] (1) Prepare the precursor solution by accurately weighing 4 g of thioacetamide, 0.25 g of ammonium metatungstate, 1.4 g of oxalic acid, and 0.6 g of nickel acetate, then add 30 ml of distilled water and stir in a 60 ° C water bath for 2 h until completely dissolved.

[0053] (2) Add 30 ml of the prepared precursor solution to the reactor, tighten the seal, place the reactor in a constant temperature drying oven, set the temperature to 200 ° C and keep it warm for 7 hours. After the temperature in the constant temperature drying oven drops to room temperature, centrifuge to separate the solid product, wash it with deionized water and anhydrous ethanol several times by centrifugation, and dry it at room temperature to obtain a Ni-doped sample;

[0054] (3) The dried sample was placed in a quartz boat and annealed in an Ar / H2 mixed gas with a hydrogen content of 5% at a flow rate of 40 mL / min. The sample was kept at 400°C for 3 h and then cooled naturally to room temperature to obtain a wooly ball-shaped NiS-WS2 product.

[0055] Example 5

[0056] This embodiment provides a method for preparing a yarn-shaped NiS-WS2 hydrogen evolution catalyst, which is obtained by the following preparation steps:

[0057] (1) Prepare the precursor solution by accurately weighing 4 g of thioacetamide, 0.15 g of ammonium metatungstate, 1.4 g of oxalic acid, and 0.45 g of nickel acetate, then add 30 ml of distilled water and stir in a 60 ° C water bath for 2 h until completely dissolved.

[0058] (2) Add 30 ml of the prepared precursor solution to the reactor, tighten the seal, place the reactor in a constant temperature drying oven, set the temperature to 200 ° C and keep it warm for 7 hours. After the temperature in the constant temperature drying oven drops to room temperature, centrifuge to separate the solid product, wash it with deionized water and anhydrous ethanol several times by centrifugation, and dry it at room temperature to obtain a Ni-doped sample;

[0059] (3) The dried sample was placed in a quartz boat and annealed in an Ar / H2 mixed gas with a hydrogen content of 5% at a flow rate of 40 mL / min. The sample was kept at 400°C for 3 h and then cooled naturally to room temperature to obtain a wooly ball-shaped NiS-WS2 product.

[0060] Example 6

[0061] This embodiment provides a method for preparing a yarn-shaped NiS-WS2 hydrogen evolution catalyst, which is obtained by the following preparation steps:

[0062] (1) Prepare the precursor solution by accurately weighing 4 g of thioacetamide, 0.25 g of ammonium metatungstate, 1.4 g of oxalic acid, and 0.45 g of nickel acetate, then add 30 ml of distilled water and stir in a 60 ° C water bath for 2 h until completely dissolved;

[0063] (2) Add 30 ml of the prepared precursor solution to the reactor, tighten the seal, place the reactor in a constant temperature drying oven, set the temperature to 200 ° C and keep it warm for 7 hours. After the temperature in the constant temperature drying oven drops to room temperature, centrifuge to separate the solid product, wash it with deionized water and anhydrous ethanol several times by centrifugation, and dry it at room temperature to obtain a Ni-doped sample;

[0064] (3) The dried sample was placed in a quartz boat and annealed in an Ar / H2 mixed gas with a hydrogen content of 5% at a flow rate of 40 mL / min. The sample was kept at 300°C for 4 h and then cooled naturally to room temperature to obtain a wooly ball-shaped NiS-WS2 product.

[0065] Performance test evaluation

[0066] This section only tests samples provided in some embodiments. Other samples also have the same or similar physical and chemical properties, which will not be described in detail here.

[0067] Combine Figure 1 As shown in the figure, the catalyst prepared in this scheme is a woolly spherical structure with a nanosphere morphology. The catalyst is MS-WS2, where M is Ni. The outer edges of the yarn spheres have raised long ridges 1 along their lengths, and multiple interconnected nanosheets 2 connect the ridges to the yarns. The diameter of the MS-WS2 nanospheres is 0.5-2 μm, and the nanosheets are 50-100 nm long and 5-20 nm thick. The catalyst can be used to catalyze hydrogen evolution reactions in acidic or alkaline media.

[0068] 1. Morphology and structure detection

[0069] The morphology of the nanospheres prepared in Examples 1-4 was tested using a scanning electron microscope (SEM). Figure 1 and Figure 8-10 The SEM images of the NiS-WS2 nanospheres obtained in Examples 1-4 are given respectively. It can be seen from the figures that the nanospheres prepared in Examples 1-4 of the present invention are wool ball-like structures with a diameter of 1.4-1.7 μm. The size of the nanosheets on the surface of the nanospheres is 50-70 nm and the thickness is 10-15 nm.

[0070] The elemental composition and content of the NiS-WS2 nanospheres prepared in Example 1 were tested using X-ray energy dispersive spectroscopy (EDX). Figure 2 The EDX spectrum of NiS-WS2 nanospheres obtained in Example 1 is given. Figure 3 The element distribution mapping spectrum of the NiS-WS2 nanospheres obtained in Example 1 is given. It is detected that the NiS-WS2 nanospheres prepared in Example 1 contain Ni, W and S elements, and the specific molar ratio of each element is 6:1:2.

[0071] The structure of the NiS-WS2 nanospheres prepared in Example 1 was characterized by X-ray diffractometer (XRD). Figure 4 The XRD patterns of the NiS-WS2 nanospheres obtained in Example 1 are given; after comparison, all the patterns are consistent with the peak shapes of the WS2 standard card (JCPDS35-0651) and the NiS standard card library (labeled: JCPDS12-0041 and JCPDS02-1280), indicating that the nanospheres prepared in the above example are NiS-WS2 mixed phases.

[0072] The structure and valence state of the NiS-WS2 nanospheres prepared in Example 1 were detected using X-ray photoelectron spectroscopy (XPS). Figure 5 The XPS spectrum of the NiS-WS2 nanospheres obtained in Example 1 is given; after comparison, the NiS-WS2 nanospheres prepared in Example 1 contain W, Ni, S, and O elements, the W element contains +4 and +6 valences, the Ni element contains 0 and +2 valences, and the S element contains -2 and +6 valences.

[0073] In summary, the NiS-WS2 nanospheres prepared by the technical solution provided by the present invention not only have uniform morphology but also have controllable size, and their diameters are regulated between 0.5-2 μm.

[0074] 2. Catalytic performance

[0075] The hydrogen evolution catalytic performance of the NiS-WS2 nanospheres prepared in Example 1 was characterized using an electrochemical workstation three-electrode system. Figure 6 and Figure 7 The hydrogen evolution polarization curves of the NiS-WS2 nanospheres obtained in Example 1 in an acidic medium (0.5M H2SO4 solution) and an alkaline medium (1M KOH solution) are shown. By comparison, the NiS-WS2 nanospheres obtained in Example 1 have catalytic performance superior to that of single-component WS2 and NiS in both acidic and alkaline media. It can be seen that the NiS-WS2 nanospheres prepared by the technical solution provided by the present invention are a highly efficient hydrogen evolution catalyst.

[0076] Obviously, the above description is merely an embodiment of the present invention, and the commonly known specific structures and characteristics of the scheme are not described in detail here. It should be noted that those skilled in the art can make a number of variations and improvements without departing from the structure of the present invention, and these should also be considered as the scope of protection of the present invention, and these will not affect the effectiveness of the implementation of the present invention and the practical application of the patent.

Claims

1. A yarn ball-shaped hydrogen evolution catalyst, characterized in that: The catalyst is a wool ball structure with a nanosphere morphology. The catalyst is MS-WS2, M is Ni, and the outer side of the line on the wool ball structure has a protruding long edge along the length direction. A plurality of interconnected nanosheets are connected between the long edge and the line.

2. A yarn ball-shaped hydrogen evolution catalyst according to claim 1, characterized in that: The diameter of the MS-WS2 nanosphere is 0.5-2 μm, the length of the nanosheet is 50-100 nm, and the thickness is 5-20 nm.

3. A yarn ball-shaped hydrogen evolution catalyst according to any one of claims 1-2, characterized in that: The catalyst can be used for catalytic hydrogen evolution reaction in acidic and alkaline media.

4. A method for preparing a yarn ball-shaped hydrogen evolution catalyst according to any one of claims 1 to 2, characterized in that: The following steps are involved: (1) Hydrothermal synthesis reaction: Place the reagents containing W source, S source and nickel acetate into a hydrothermal reactor, dissolve the reagents in water, and heat the reactor to 120-220°C for reaction for 1-8 hours; (2) filtering, washing, and drying the solid-liquid mixture obtained after the reaction in step (1) to obtain a NiWS precursor; (3) Reducing atmosphere annealing: The NiWS precursor material in step (1) is heated to 100-400°C in a reducing atmosphere of Ar / H2 mixed gas and kept warm for 10-300 minutes to obtain NiS-WS2 nanospheres.

5. The method for preparing a yarn ball-shaped hydrogen evolution catalyst according to claim 4, wherein: In step (1), the molar mass ratio of the raw materials W source, S source and nickel acetate is (1-7): (0.5-1.5): 2; the W source is ammonium metatungstate, and the S source is thioacetamide.

6. The method for preparing a yarn ball-shaped hydrogen evolution catalyst according to claim 5, wherein: The heating rate of the hydrothermal synthesis reaction in step (1) is 2-5°C / min, the heating rate of the reducing atmosphere annealing reaction is 2-5°C / min, and the reaction time is 0.5-3h.

7. The method for preparing a yarn ball-shaped hydrogen evolution catalyst according to claim 6, wherein: The volume fraction of hydrogen in step (3) is 1%-5%, and the flow rate of the Ar / H2 mixed gas is 5-40 mL / min.

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