Preparation method and application of carbon nanotube wound S-doped Se vacancy type NiSe2 electrocatalyst

Abstract

The invention discloses a preparation method and application of a carbon nanotube wound S-doped Se vacancy type NiSe2 electrocatalyst, and belongs to the technical field of catalytic materials. The electrocatalyst material provided by the invention adopts a hydrothermal-solid phase heat treatment combined preparation method, and comprises the following steps: firstly, preparing a carbon nanotube loaded Ni (OH) 2 nanosheet precursor by adopting a hydrothermal reaction, then obtaining a carbon nanotube wound S-doped NiSe2 electrocatalyst by adopting the hydrothermal reaction, and finally, carrying out heat treatment in an inert atmosphere, and introducing Se vacancy. According to the invention, a two-in-one strategy is adopted to design and prepare the carbon nanotube wound S-doped NiSe2 electrocatalyst with rich Se vacancy. The staggered and wound carbon nanotubes provide an integrated conductive network, the introduction of S atoms and Se vacancies improves the oxygen evolution reaction activity of the electrocatalyst, and the electrocatalyst has wide application prospects in the fields of water electrolysis and metal-air batteries.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic materials, and in particular relates to a preparation method and application of a carbon nanotube-wrapped S-doped Se vacancy type NiSe2 electrocatalyst. Background Art

[0002] With the rapid growth of population and the development of industry, the global energy demand has increased rapidly, stimulating social energy consumption and increasing the environmental burden. The global energy supply and the resulting environmental problems are prompting researchers to seek renewable, clean and alternative energy to replace the gradually depleting and polluting fossil fuels. At present, sustainable green energy includes solar energy, tidal energy, wind energy, hydropower and hydrogen energy. Among them, hydrogen, an abundant element on the earth, has a high energy density and is considered to be the most promising alternative to traditional energy.

[0003] Unfortunately, due to the slow kinetics of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), especially the huge energy barrier caused by the four-step proton-coupled electron transfer of OER, an effective catalyst is needed to narrow the gap between the theoretical potential and the actual required potential. Therefore, catalysts play a key role in designing efficient processes and systems to maximize the value of raw materials to meet energy needs and achieve the future sustainable energy and industrial large-scale hydrogen production goals.

[0004] Nowadays, non-precious metal-based catalysts have the highest cost-effectiveness, and more and more people are committed to the development of transition metal-based electrocatalysts, which mainly include transition metal oxides, phosphides, sulfides, selenides and nitrides. Through a series of reasonable means such as doping heteroatoms, constructing heterojunction interfaces and introducing defects or vacancies to optimize electrocatalytic performance, many transition metal-based electrocatalysts have catalytic activities comparable to those of precious metal-based catalysts. However, despite the remarkable results achieved in the above research, non-precious metal catalysts are still limited by insufficient active sites and slow reaction kinetics, which affects their application in the field of water electrolysis. Summary of the invention

[0005] In view of the above-mentioned problems, the present invention provides a method for preparing a carbon nanotube-wrapped S-doped Se vacancy-type NiSe2 electrocatalyst. The electrocatalyst material involved in the present invention adopts a preparation method combining hydrothermal and solid phase heat treatment, and the steps include firstly preparing a carbon nanotube-loaded Ni(OH)2 nanosheet precursor by hydrothermal reaction, then obtaining a carbon nanotube-wrapped S-doped NiSe2 electrocatalyst by hydrothermal reaction, and finally heat treating in an inert atmosphere to introduce Se vacancies.

[0006] The technical solution adopted by the present invention is specifically as follows:

[0007] (1) dissolving carbon nanotubes, nickel salt, urotropine, citrate and polyvinyl pyrrolidone in a deionized water / ethanol mixed solution, mixing them evenly, subjecting them to a hydrothermal reaction at a specific temperature for a certain period of time, and after the reaction, centrifuging, washing and drying to obtain a carbon nanotube-loaded Ni(OH)2 nanosheet precursor;

[0008] (2) dispersing the precursor described in S1 in an aqueous solution containing a sulfur source and a selenium source, transferring the precursor to a high-pressure hydrothermal autoclave, selecting a suitable temperature and time for reaction, and then centrifuging, washing, and drying to obtain a carbon nanotube-wrapped S-doped NiSe2 electrocatalyst;

[0009] (3) The powder obtained in S2 is calcined under an inert atmosphere by selecting and setting a suitable heating rate, calcination temperature and calcination time to obtain a carbon nanotube-wrapped S-doped Se vacancy-type NiSe2 electrocatalyst.

[0010] Wherein, in step (1), the nickel salt includes but is not limited to one or more of nickel nitrate, nickel sulfate, nickel chloride and nickel acetate, and its concentration is 5 to 50 mmol L -1 ; Hydrothermal temperature is 90~150℃; Hydrothermal time is 5~12h.

[0011] Wherein, in step (2), the sulfur source includes but is not limited to sodium thiosulfate, sodium sulfite, thiourea, sodium sulfide, thioacetamide, etc.; the selenium source includes but is not limited to sodium selenate, sodium selenide, selenourea, sodium selenite, sodium selenide, etc.; the sulfur source concentration is 10 to 100 mmol L -1 ; Selenium source concentration is 10~100mmol L -1 ; Hydrothermal temperature is 100-200℃; Hydrothermal time is 10-48h.

[0012] Wherein, in step (3), the inert atmosphere includes nitrogen, argon, and helium; the heating rate is 1 to 20°C min -1 ; The target temperature is 250~450℃; The insulation time is 0.5~6h.

[0013] Another aspect of the present invention provides a carbon nanotube-wrapped S-doped Se vacancy-type NiSe2 electrocatalyst prepared by the above-mentioned preparation method.

[0014] The present invention also provides the use of the above-mentioned carbon nanotube-wrapped S-doped Se vacancy type NiSe2 electrocatalyst in water electrolysis or metal-air batteries.

[0015] The beneficial effects of the present invention compared with the prior art are as follows:

[0016] The stability of the OER activity of the carbon nanotube-wrapped S-doped Se vacancy-type NiSe2 electrocatalyst under alkaline conditions is superior to that of commercial noble metal catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention, the drawings related to the embodiments are briefly introduced below.

[0018] Figure 1 The XRD patterns of the samples prepared in Example 1, Comparative Example 1 and Comparative Example 2 are shown in FIG.

[0019] Figure 2 SEM images of samples prepared in Example 1 (Figure c), Comparative Example 1 (Figure b) and Comparative Example 2 (Figure a).

[0020] Figure 3 This is the OER performance LSV curve obtained in Example 2.

[0021] Figure 4 The LSV curve and stability curve of the full water electrolysis obtained in Example 2. DETAILED DESCRIPTION

[0022] The present invention is described in detail below in conjunction with embodiments, but the embodiments of the present invention are not limited thereto. Obviously, the embodiments described below are only partial embodiments of the present invention. For those skilled in the art, other similar embodiments obtained without creative work all fall within the protection scope of the present invention.

[0023] Embodiment 1:

[0024] (1) Add 40 mg of PVP to a 10 ml ethanol / 40 ml water mixture, add 40 mg of carbon nanotubes after dissolving, and disperse evenly by ultrasonication for 2 hours. Add nickel nitrate (0.3 mmol, 0.0872 g) and stir for 5 min. Add urotropine (0.5 mmol, 0.0701 g) and sodium citrate (0.05 mmol, 0.0147 g) and stir for 10 min. Hydrothermally react at 90 °C for 6 h, and cool to room temperature. Centrifuge (wash 3 times with ethanol, 10000 r / 10 min), and vacuum dry at 70 °C for 12 h.

[0025] (2) Add 30 mg of the above product to 20 ml of water, stir for 3 h, and sonicate for 2 h to disperse evenly. Add 60 mg of sodium thiosulfate and sonicate until all solids are dissolved. Pass nitrogen through the above solution for 30 min. Add 1.5 ml of sodium hydride selenide dropwise. Heat the autoclave at 150 ° C for 36 h and cool to room temperature. Centrifuge, wash with water 3 times and ethanol 3 times. Dry in a vacuum oven at 80 ° C for 12 h to obtain S-NiSe2 / CNTs.

[0026] (3) The above samples were placed in a tube furnace and heat treated at 450 °C for 0.5 h in a nitrogen atmosphere with a heating rate of 10 °C min -1After cooling to room temperature, a black powder (S-NiSe2-V Se / CNTs).

[0027] Example 2

[0028] In the electrolysis of water in this embodiment, the prepared material is dispersed in ethanol to prepare a dispersion, and the dispersion is then coated on the carbon cloth; the electrolyte is a 1M KOH aqueous solution.

[0029] Comparative Example 1:

[0030] The experiment of this embodiment is the same as that of embodiment 1, except that the heat treatment in step (3) is not performed.

[0031] Comparative Example 2:

[0032] The experiments of this embodiment and comparative example 1 are the same, except that sodium thiosulfate is not added during the hydrothermal process.

[0033] Figure 1 The XRD patterns of the samples prepared in Example 1, Comparative Example 1 and Comparative Example 2 are shown in FIG.

[0034] Figure 2 SEM images of samples prepared in Example 1 (Figure c), Comparative Example 1 (Figure b) and Comparative Example 2 (Figure a).

[0035] Figure 3 This is the OER performance LSV curve obtained in Example 2.

[0036] Figure 4 The LSV curve and stability curve of the full water electrolysis obtained in Example 2.

[0037] It should be noted that the above embodiments are only for further illustrating the content of the present invention and should not be construed as limiting the present invention. Without departing from the spirit and essence of the present invention, modifications or substitutions made to the methods, steps or conditions of the present invention all fall within the scope of the present invention.

Claims

1. A carbon nanotube-wrapped S-doped Se vacancy type NiSe2 electrocatalyst, characterized in that: The carbon nanotubes in the catalyst are intertwined to form an integrated conductive network.

2. A carbon nanotube-wrapped S-doped Se vacancy type NiSe2 electrocatalyst, characterized in that: The catalyst NiSe2 is doped with S atoms.

3. A carbon nanotube-wrapped S-doped Se vacancy type NiSe2 electrocatalyst, characterized in that: There are abundant Se vacancies in the catalyst NiSe2.

4. A method for preparing a carbon nanotube-wrapped S-doped Se vacancy type NiSe2 electrocatalyst as claimed in claims 1, 2 and 3, characterized in that The following steps are involved: S1: dissolving carbon nanotubes, nickel salt, urotropine, citrate and polyvinyl pyrrolidone in a deionized water / ethanol mixed solution, mixing evenly, and subjecting to hydrothermal reaction at a specific temperature for a certain period of time. After the reaction, centrifuging, washing and drying are performed to obtain a carbon nanotube-loaded Ni(OH)2 nanosheet precursor; S2: dispersing the precursor described in S1 in an aqueous solution containing a sulfur source and a selenium source, and then transferring it to a high-pressure hydrothermal autoclave to select a suitable temperature and time for reaction, and then centrifuging, washing, and drying to obtain a carbon nanotube-wrapped S-doped NiSe2 electrocatalyst; S3: The powder obtained in S2 is calcined under an inert atmosphere by selecting and setting a suitable heating rate, calcination temperature and calcination time to obtain a carbon nanotube-wrapped S-doped Se vacancy-type NiSe2 electrocatalyst.

5. The preparation method according to claim 4, characterized in that: In step S1, the nickel salt includes but is not limited to one or more of nickel nitrate, nickel sulfate, nickel chloride and nickel acetate, and its concentration is 5 to 50 mmol L -1 ; Hydrothermal temperature is 90~150℃; Hydrothermal time is 5~12h.

6. The preparation method according to claim 4, characterized in that: In step S2, the sulfur source includes but is not limited to sodium thiosulfate, sodium sulfite, thiourea, sodium sulfide, thioacetamide, etc.; the selenium source includes but is not limited to sodium selenate, sodium selenide, selenourea, sodium selenite, sodium selenide, etc.; the sulfur source concentration is 10 to 100 mmol L -1 ; Selenium source concentration is 10~100mmol L -1 ; Hydrothermal temperature is 100-200℃; Hydrothermal time is 10-48h.

7. The preparation method according to claim 4, characterized in that: In step S3, the inert atmosphere includes nitrogen, argon, and helium; the heating rate is 1-20°C min -1 ; The target temperature is 250~450℃; The insulation time is 0.5~6h.

8. The carbon nanotube-entangled S-doped Se vacancy-type NiSe2 electrocatalyst prepared by the preparation method according to any one of claims 4 to 7.

9. Use of the carbon nanotube-wrapped S-doped Se vacancy-type NiSe2 electrocatalyst according to claim 8 in water electrolysis and metal-air batteries.

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