Low-temperature plasma modified efficient hydrogen evolution catalyst

Abstract

The invention discloses a low-temperature plasma modified efficient hydrogen evolution catalyst. The method comprises the following steps: preparing a nano core-shell structure catalyst with uniform size through liquid-phase synthesis and layer-by-layer self-assembly, and introducing vacancies, defects and other unsaturated active sites on the surface of the nano core-shell structure catalyst; and then nitrogen and the like are used as a reaction atmosphere of a plasma chamber, and the surface of the catalyst is treated through a low-temperature plasma technology for catalyst performance regulation and control. The method has the advantages of simple process, low energy consumption, no need of adding extra chemical reagents, environmental friendliness and the like, and has a good application prospect. The preparation and regulation method of the electrocatalyst can be suitable for application of an electrocatalytic efficient hydrogen evolution catalyst. The material regulated and controlled by the plasma has higher current density and lower overpotential in hydrogen evolution reaction, and shows more excellent electrocatalytic activity and stability.

Description

Technical Field

[0001] This invention belongs to the field of plasma technology, specifically relating to a highly efficient hydrogen evolution catalyst with a uniform nano-core-shell structure coupled with low-temperature plasma modification. Background Technology

[0002] It is well understood that the performance of electrocatalysts depends on their surface properties. Plasma is an ionized substance that is generated when sufficient energy is applied to a gaseous medium or gas mixture. The energy sources for plasma generation are diverse, including flames, combustion, heat, discharges (such as plasma jets, sparks, arcs, glow discharges, corona discharges, radio frequencies [RF], and microwaves), dielectric barrier discharges (DBD), and shocks driven by electrical, magnetic, and chemical reactions. As early as the 1990s, plasma technology was favored by researchers as an alternative method for catalyst preparation. Besides direct synthesis, plasma technology has also been widely used in the surface modification of electro-triple catalysts (also known as plasma-enhanced catalyst preparation). Depending on the energy level, the generated plasma can be classified as high-temperature plasma and low-temperature plasma. The plasmas used in laboratory and industrial catalyst preparation and treatment are typically low-temperature plasmas. In low-temperature plasmas, the plasma used for catalyst surface modification usually refers to non-thermal plasmas, also known as cold plasmas or non-equilibrium plasmas. The high-energy ions in plasma have higher chemical reactivity than ions in diffusion-limited thermal reactions, making plasma surface treatment a powerful tool for electrocatalyst modification.

[0003] Modifying the structure and surface of electrocatalysts can yield excellent electrocatalytic activity and efficiency. Among various surface modification strategies, nonthermal plasma technology plays an irreplaceable role due to its advantages such as simple and controllable operation, low pollution, low cost, and ease of large-scale application. Nonthermal plasma treatment is a powerful tool for material surface and structural engineering, primarily beneficial for electrocatalytic reactions involving surface atomic doping or reconstruction, introduction of vacancies or defects, partial surface reduction or oxidation, and increased porosity or roughness. Due to the flexibility of plasma modification, this technology is becoming increasingly popular. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a highly efficient hydrogen evolution catalyst with a uniform nano-core-shell structure coupled with low-temperature plasma modification.

[0005] The purpose of this invention is to propose a highly efficient hydrogen evolution catalyst with a uniform nano-core-shell structure coupled with low-temperature plasma modification.

[0006] Another object of the present invention is to provide a method for preparing manganese-based sulfide electrocatalysts and electrodes based on the above-mentioned low-temperature plasma technology.

[0007] Another object of the present invention is to provide the application of the above-mentioned electrocatalyst in the electrolysis of water to produce hydrogen.

[0008] The objective of this invention is achieved by at least one of the following technical solutions.

[0009] This invention first prepares a manganese-based catalyst using a liquid-phase synthesis method and a SiO2 template method. Then, using nitrogen as the discharge gas in a plasma treatment chamber, the manganese-based catalyst is surface-treated using low-temperature plasma technology to introduce defects onto its surface. Electrodes are fabricated using the plasma-treated material and applied to the cathode of the water electrolysis hydrogen evolution reaction, effectively improving its electrocatalytic performance and stability.

[0010] The present invention provides a method for preparing a highly efficient hydrogen evolution catalyst with a uniform nano-core-shell structure coupled with low-temperature plasma modification, comprising the following steps: (1) Mix anhydrous ethanol, ammonia and water evenly, then add tetraethyl orthosilicate to react and obtain template SiO2; (2) The template SiO2 was dissolved in ethanol and ultrasonically dispersed, and the thioacetamide was completely dissolved in water. Then the template SiO2 and thioacetamide were mixed evenly, and acetate was added. The mixture was heated to obtain the template catalyst. (3) Disperse the template catalyst described in step (2) in anhydrous ethanol, add 1M NaOH and stir to obtain a manganese-based catalyst; (4) Grind the manganese-based catalyst described in step (3) and place it evenly into the plasma treatment chamber. Introduce the reaction gas and perform plasma treatment to obtain the hydrogen evolution electrocatalyst with low-temperature plasma regulation performance.

[0011] (5) Plasma technology treatment: The catalyst described in step (4) is ground and then placed evenly on a plasma treatment platform (quartz plate). Reaction gas is introduced and plasma treatment is performed to obtain the hydrogen evolution electrocatalyst with low-temperature plasma-regulated performance.

[0012] Further, in step (1), according to the mass parts, anhydrous ethanol is 120 parts, water is 50 parts, ammonia is 20 parts, and tetraethyl orthosilicate is 10 parts; in step (2), the heating reaction temperature is 60°C and the heating reaction time is 12h.

[0013] Furthermore, the reaction gas in step (4) is nitrogen, and the gas flow rate in the reactor in step (4) is 30 sccm.

[0014] Furthermore, the discharge power of the plasma treatment in step (4) is 80W, the plasma treatment time is 30s, and the plasma treatment temperature is 20-30℃.

[0015] Preferably, before introducing the reaction gas in step (4), the reactor is evacuated for more than 20 minutes to ensure that no other gas remains.

[0016] In step (4), after plasma treatment, the catalyst obtained is a manganese sulfide catalyst material rich in vacancies and defects.

[0017] This invention provides a highly efficient hydrogen evolution catalyst with a uniform nano-core-shell structure coupled with low-temperature plasma modification, prepared by the above-described method.

[0018] The application of the hydrogen evolution electrocatalyst with a uniform nano-core-shell structure coupled with low-temperature plasma modification provided by this invention in the electrolysis of water for hydrogen evolution includes the following steps: (1) Electrode material preparation: The hydrogen evolution electrocatalyst with low-temperature plasma regulation performance is added to a solvent and dispersed evenly to obtain catalyst ink. Then, the catalyst ink is drop-coated onto a glassy carbon disk electrode to obtain an electrode material containing the catalyst. (2) Using the catalyst-containing electrode material described in step (1) as the working electrode, a platinum mesh as the counter electrode, Hg / HgO as the reference electrode, and potassium hydroxide as the electrolyte, perform the water electrolysis and hydrogen evolution reaction.

[0019] Further, the solvent in step (1) is a mixture of ethanol and Nafion solution, wherein the volume ratio of ethanol to Nafion solution is 800:200; and the concentration of Nafion solution is 20 ± 0.5 wt%. Preferably, the concentration of the Nafion solution is 20 wt%.

[0020] Furthermore, the concentration of the hydrogen evolution electrocatalyst with low-temperature plasma-modulated performance in the solvent is 5 mg / mL.

[0021] Furthermore, the glassy carbon disk electrode in step (1) is a 3mm glassy carbon disk electrode; Further, the method of uniform dispersion in step (1) is ultrasonic dispersion treatment, and the ultrasonic dispersion treatment time is 0.5h.

[0022] Furthermore, the concentration of the potassium hydroxide electrolyte in step (2) is 1 mol / L.

[0023] The low-temperature plasma treatment technology involved in this invention has advantages such as simple process, low energy consumption, no need to add additional chemical reagents, and environmental friendliness. This technology can flexibly and controllably adjust the properties of materials, has the advantages of strong universality and good application prospects, and is expected to become an important technical means for catalyst and semiconductor surface modification.

[0024] The highly efficient hydrogen evolution catalyst with a uniform nanostructure coupled with low-temperature plasma modification provided by this invention can be effectively applied to the hydrogen evolution reaction in water electrolysis. After treatment, the material surface is modified and defect-controlled, introducing a large number of vacancies, increasing active sites, improving hydrophilicity, and enhancing surface state concentration. These modified properties effectively promote charge transfer at the catalyst / solution interface, exhibiting higher current density, lower overpotential, and higher stability in the hydrogen evolution reaction in water electrolysis, demonstrating superior catalytic activity and stability. Therefore, the technology provided by this invention has very broad application prospects.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The preparation method provided by the present invention uses low-temperature plasma technology to regulate manganese-based sulfides. The process is simple, the preparation cycle is short, the material cost is low, the energy consumption is small, and no other chemical reagents are introduced, thus avoiding secondary pollution.

[0026] (2) The preparation method provided by the present invention has a wide range of applications, and the raw materials used have been mass-produced, are widely available, and are inexpensive.

[0027] (3) In the preparation method provided by the present invention, the defect concentration on the surface of the transition metal sulfide material can be easily controlled by controlling the reaction gas atmosphere, plasma treatment power and treatment time through low temperature plasma treatment.

[0028] (4) In the preparation method provided by the present invention, the manganese sulfide material after being controlled by low temperature plasma technology has higher current density, lower overpotential and higher stability in the hydrogen evolution reaction of water electrolysis. Attached Figure Description

[0029] Figure 1 The image shows a scanning electron microscope (SEM) image of the catalyst obtained in step (1) of Example 1 before and after 30 s of low-temperature plasma treatment. Figure 2 The image is a high-resolution transmission electron microscope (HRTEM) image of the copper-based catalyst obtained in step (1) of Example 1 after being subjected to low-temperature plasma treatment for 30 s. Figure 3 The images show the X-ray diffraction (XRD) patterns of the catalyst materials obtained in Example 1 and Example 2. Figure 4 The images show the electron paramagnetic resonance (EPR) diagrams of the catalyst material obtained in Example 2 and the catalyst material obtained in Comparative Example 1. Figure 5 The polarization curves of the catalyst materials obtained in Example 1 and Example 2 for the hydrogen evolution reaction are shown. Figure 6 Tafel curves of the catalyst materials obtained in Example 1 and Example 2 for the hydrogen evolution reaction; Figure 7 The electrochemical active area diagrams are for the catalyst materials obtained in Example 1 and Example 2. Figure 8 The electrochemical stability diagrams are for the catalyst materials obtained in Example 1 and Example 2. Detailed Implementation

[0030] The following examples further illustrate specific implementations of the present invention, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described in detail below are implementations or understandings that can be achieved or understood by those skilled in the art with reference to existing technology. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] Example 1 A method for preparing a hydrogen evolution electrocatalyst with low-temperature plasma-modulated performance includes the following steps: (1) Mix anhydrous ethanol, ammonia and water evenly, then add tetraethyl orthosilicate to react and obtain template SiO2; dissolve template SiO2 in ethanol and disperse it ultrasonically, and completely dissolve thioacetamide in water, then mix template SiO2 and thioacetamide evenly, then add manganese acetate and cobalt acetate, and heat to react and obtain template catalyst; disperse template catalyst in anhydrous ethanol, add 1M NaOH and stir to obtain manganese-based catalyst.

[0032] (2) Low-temperature plasma technology treatment: The catalyst obtained in step (1) is ground and uniformly placed in the plasma treatment chamber, nitrogen gas is introduced, and plasma treatment is carried out. The plasma treatment power is 80W and the plasma treatment time is 10s to obtain the electrocatalyst with low-temperature plasma regulation performance.

[0033] (3) Disperse 5 mg of the hydrogen evolution electrocatalyst with low-temperature plasma-controlled performance in 1 mL of solvent and ultrasonically disperse it evenly to obtain catalyst ink; the solvent is a mixture of 800 μL ethanol and 200 μL Nafion solution; the mass percentage concentration of the Nafion solution is 20 wt%; take 10 μL of the catalyst ink and drop it onto a glassy carbon disk electrode (3 mm) to obtain catalyst electrode material, labeled as N2-10 (corresponding to a plasma treatment time of 10 s).

[0034] Comparative Example 1 A method for preparing an electrocatalyst includes the following steps: (1) Mix anhydrous ethanol, ammonia and water evenly, then add tetraethyl orthosilicate to react and obtain template SiO2; dissolve template SiO2 in ethanol and disperse it ultrasonically, and completely dissolve thioacetamide in water, then mix template SiO2 and thioacetamide evenly, then add manganese acetate and cobalt acetate, and heat to react and obtain template catalyst; disperse template catalyst in anhydrous ethanol, add 1M NaOH and stir to obtain manganese-based catalyst.

[0035] (2) Disperse 5 mg of the hydrogen evolution electrocatalyst in 1 mL of solvent and ultrasonically disperse it evenly to obtain catalyst ink; the solvent is a mixture of 800 μL ethanol and 200 μL Nafion solution; the mass percentage concentration of the Nafion solution is 20 wt%; take 10 μL of the catalyst ink and drop it onto the glassy carbon disk electrode (3 mm) to obtain catalyst electrode material, and mark the blank control group.

[0036] Example 2 A method for preparing a hydrogen evolution electrocatalyst with performance modulated by low-temperature argon plasma includes the following steps: (1) Mix anhydrous ethanol, ammonia and water evenly, then add tetraethyl orthosilicate to react and obtain template SiO2; dissolve template SiO2 in ethanol and disperse it ultrasonically, and completely dissolve thioacetamide in water, then mix template SiO2 and thioacetamide evenly, then add manganese acetate and cobalt acetate, and heat to react and obtain template catalyst; disperse template catalyst in anhydrous ethanol, add 1M NaOH and stir to obtain manganese-based catalyst.

[0037] (2) Low-temperature plasma technology treatment: The catalyst obtained in step (1) is ground and uniformly placed in the plasma treatment chamber. Argon gas is introduced to carry out plasma treatment. The pressure of the low-temperature plasma chamber is atmospheric pressure, the power of plasma treatment is 80W, and the plasma treatment time is 10s and 30s respectively, to obtain an electrocatalyst whose performance is regulated by argon plasma.

[0038] (3) 5 mg of the hydrogen evolution electrocatalyst with low-temperature plasma-controlled performance was dispersed in 1 mL of solvent and ultrasonically dispersed to obtain catalyst ink; the solvent was a mixture of 800 μL ethanol and 200 μL Nafion solution; the mass percentage concentration of the Nafion solution was 20 wt%; 10 μL of the catalyst ink was drop-coated onto a glassy carbon disk electrode (3 mm) to obtain catalyst electrode materials, which were labeled as Ar-10 and Ar-30 respectively (corresponding to plasma treatment times of 10 s and 30 s respectively).

[0039] Effect verification The scanning electron microscope (SEM) images of the catalyst obtained in step (1) of Example 1 before and after 30 s of low-temperature plasma treatment are shown below. Figure 1 As shown, the obtained sample consists of nanoparticles with an average particle size of approximately 500 nm, and there is no significant structural difference between the sample before and after plasma treatment.

[0040] The high-resolution transmission electron microscope (HRTEM) image of the catalyst obtained in step (1) of Example 1 after being subjected to low-temperature plasma treatment for 30 s is shown below. Figure 2 As shown, the lattice spacing of the obtained sample is 0.303 nm, corresponding to the (101) crystal plane of MnS.

[0041] The X-ray diffraction (XRD) pattern of the catalyst material obtained in Example 1 is shown below. Figure 3 As shown, the spectrum of the sample obtained in the example was found to be consistent with that of MnS (PDF NO.88-2223), with no impurities, and the sample after plasma treatment did not show obvious changes in crystal structure.

[0042] The electron paramagnetic resonance (EPR) images of the catalyst materials obtained in Example 1 and Comparative Example 1 are shown below. Figure 5 As shown, the signal intensity (g=2.003) of the samples obtained in Examples and Comparative Example 1 increased by 65% ​​compared with that of the sample in Comparative Example 1, indicating an enhancement of the material vacancy concentration.

[0043] The catalyst electrode materials obtained in this embodiment, before and after low-temperature plasma technology modulation, were used in the hydrogen evolution reaction of water electrolysis. The test conditions were as follows: the experiment used a CHI660E electrochemical workstation from Shanghai Chenhua, with a standard three-electrode system as the test system. The catalyst electrode materials of Example 1 and Comparative Example 1 were used as working electrodes, respectively, with a platinum mesh as the counter electrode, saturated Ag / AgCl as the reference electrode, and 1M KOH solution as the electrolyte. The polarization curves were measured at room temperature at a scan rate of 5 mV / s. The polarization curves of the catalyst obtained in Example 1 and the comparative example are shown below. Figure 6As shown, the overpotential of the plasma-controlled catalyst provided in this embodiment of the invention for the hydrogen evolution reaction is significantly lower than that of the original untreated catalyst material in Comparative Example 1.

[0044] The polarization curves of the catalyst electrode materials obtained in Example 1 and Example 2 for the hydrogen evolution reaction are as follows: Figure 6 As shown, the overpotential of the plasma-modified catalyst provided by this invention can be reduced by 10% to 50% compared with samples treated under other atmospheres and for different times, indicating that the catalytic activity of the material is effectively improved after plasma modification.

[0045] The electrochemical activity area curves of the catalyst electrode materials obtained in Example 1 and Example 2 for the hydrogen evolution reaction are shown below. Figure 8 As shown, the slope of the plasma-modified catalyst curve provided by this invention is 2 to 4 times higher than that of samples treated with other atmospheres and times, indicating that the number of active sites can be increased by 200% to 400% after plasma modification.

[0046] Combination Figures 1-8 It is known that plasma modulation is an effective means to improve the electrocatalytic activity of catalysts. This invention employs low-temperature plasma technology to modulate plasma defects in the catalyst, successfully introducing defects onto the material surface. The plasma-modified catalyst obtained in this embodiment exhibits increased vacancy concentration on the surface, enhancing charge transfer at the catalyst / solution interface and demonstrating excellent catalytic performance. Notably, low-temperature plasma technology is simple to operate, requires no additional chemical reagents, does not alter the morphology, structure, or phase of the catalyst material, and is environmentally friendly, making it a viable surface modification technique in the field of catalysis.

Claims

1. This invention discloses a highly efficient hydrogen evolution catalyst with a uniform nano-core-shell structure coupled with low-temperature plasma modification, the preparation method of which includes the following steps: (1) Mix anhydrous ethanol, ammonia and water evenly, then add tetraethyl orthosilicate to react and obtain template SiO2; (2) The template SiO2 was dissolved in ethanol and ultrasonically dispersed, and the thioacetamide was completely dissolved in water. Then the template SiO2 and thioacetamide were mixed evenly, and manganese acetate and cobalt acetate were added. The mixture was heated to carry out the reaction, thereby obtaining the template catalyst. (3) Disperse the template catalyst described in step (2) in anhydrous ethanol, add 1M NaOH and stir to obtain a manganese-based catalyst; (4) Grind the manganese-based catalyst described in step (3) and place it evenly in the plasma treatment chamber. Introduce the reaction gas and perform plasma treatment to obtain the hydrogen evolution electrocatalyst with low-temperature plasma regulation performance.

2. The preparation method according to claim 1, characterized in that, The reaction gas in step (4) is nitrogen. In step (4), the gas flow rate in the reactor is 30 sccm. The discharge power of the plasma treatment in step (4) is 80W. The plasma treatment time is 30s. The plasma treatment temperature is 20-30℃.

3. The application of the high-efficiency hydrogen evolution catalyst with uniform nano-core-shell structure coupled with low-temperature plasma modification as described in claim 1 in hydrogen evolution through water electrolysis, characterized in that... Includes the following steps: (1) The hydrogen evolution electrocatalyst with low-temperature plasma-controlled performance is added to a solvent and dispersed evenly to obtain a catalyst ink. Then, the catalyst ink is drop-coated onto a glassy carbon disk electrode to obtain an electrode material containing the catalyst. In particular, the solvent is a mixture of ethanol and Nafion solution, the volume ratio of ethanol to Nafion solution is 800:200, the concentration of Nafion solution is 20±0.5wt%, and the concentration of the hydrogen evolution electrocatalyst with low-temperature plasma-controlled performance in the solvent is 5mg / mL. (2) Using the catalyst-containing electrode material described in step (1) as the working electrode, a platinum mesh as the counter electrode, Hg / HgO as the reference electrode, and potassium hydroxide as the electrolyte, perform the water electrolysis and hydrogen evolution reaction.

4. The application of the high-efficiency hydrogen evolution catalyst with uniform nano-core-shell structure coupled with low-temperature plasma modification as described in claim 1 in hydrogen evolution through water electrolysis, characterized in that, Includes the following steps: (1) The high-efficiency hydrogen evolution catalyst with uniform nano-core-shell structure coupled with low-temperature plasma modification has a very uniform nanostructure, usually around 350 nm. Its morphology and structure can be observed by scanning electron microscopy, and its lattice can be analyzed by high-resolution spectroscopy of X-ray diffraction and transmission electron microscopy. (2) The performance of the catalyst-containing electrode material described in step (1) was tested by a three-electrode system. The hydrogen evolution overpotential was reduced by 10% to 50% compared with that of the catalyst without plasma treatment and the catalyst with changed plasma control parameters. (3) The electrode material containing the catalyst described in step (1) was subjected to electron spin resonance testing, and its vacancy signal intensity was increased by approximately 65% ​​compared to the catalyst without plasma treatment.

Images