A chlorine-corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode and its preparation method and application

Abstract

The present invention discloses a modified ferric oxyhydroxide / sulfide hierarchical oxygen evolution electrode resistant to chlorine corrosion, and its preparation method and application. The present invention uses a pretreated nickel mesh (NM) as a substrate, directly grows a nickel sulfide (Ni3S2) nanosheet array on the substrate surface by a hydrothermal method, and then in situ grows a modified ferric oxyhydroxide-based (Ta‑FeOOH) catalyst with a nanosheet cluster morphology on the nickel sulfide surface by an etching method, thereby constructing a hierarchical oxygen evolution electrode. The Ta‑FeOOH / Ni3S2 / NM electrode prepared by this method effectively regulates the electronic structure inside the catalyst through multi-level interface design and element doping strategy, thereby improving the oxygen evolution performance of the electrode. At the same time, the composite structure of FeOOH / Ni3S2 induces the reaction of chloride ions Cl by the reasonable introduction of anion intercalation. ‑ The like-charge repulsion reduces the corrosion and oxidation of chloride ions at the oxygen evolution active sites, demonstrating the excellent chloride corrosion resistance of the oxygen evolution electrode and providing strong support for the development of seawater electrolysis technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysis, and in particular relates to a chlorine-corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode, a preparation method and an application thereof. Background Art

[0002] As a clean and efficient energy carrier, hydrogen energy has significant advantages in promoting deep decarbonization of the energy system. Among them, green hydrogen generated by water electrolysis technology using renewable energy is regarded as an ideal way to produce hydrogen energy. Compared with the traditional water electrolysis process, seawater electrolysis for hydrogen production has the unique advantages of abundant resources and no reliance on scarce fresh water resources, as well as high hydrogen production efficiency and controllable reaction conditions under alkaline conditions, providing a highly promising option for large-scale production of green hydrogen. However, in the process of hydrogen production by seawater electrolysis, the oxygen evolution reaction occurring on the anode involves a four-electron transfer mechanism, which results in a relatively slow reaction kinetics process, becoming one of the key factors restricting the overall hydrogen production efficiency. In addition, the high concentration of chloride ions (Cl - ) not only triggers a chlorine oxidation side reaction at the anode, reducing the efficiency of the oxygen evolution reaction, but also causes severe corrosion of the electrode material, leading to increased voltage and even electrode damage, affecting the water electrolysis reaction. Therefore, it is particularly important to develop highly active and stable seawater electrolytic oxygen evolution electrodes.

[0003] Although anode electrodes based on noble metals such as Ir and Ru and their oxides exhibit excellent activity in the oxygen evolution reaction (OER), their large-scale industrial application is limited by the scarcity and high cost of precious metal resources. Given the abundance of transition metal-based catalysts in the Earth's crust and their easily tunable physical and chemical properties, developing transition metal-based OER electrodes that combine chloride corrosion resistance with high activity and stability has become a key research direction in seawater electrolysis for hydrogen production.

[0004] Studies have shown that by constructing a hierarchical structure and implementing a synergistic strategy of element doping, the utilization rate of catalytic active sites can be effectively improved, space charge migration can be promoted, and the energy barrier of the oxygen evolution reaction can be reduced, effectively driving the efficient electrolysis of seawater. Among them, transition metal hydroxide oxides (TMOOHs) can not only improve the oxygen evolution activity, but also give the catalyst excellent resistance to chloride corrosion. In addition, transition metal sulfides have been shown to reconstruct under strong electrochemical oxidation conditions, and the corresponding polyatomic anion sulfate SO4 will be formed under the application of bias during the anodic oxygen evolution process. 2-, migrate and insert into the hierarchical nanostructure to form anion intercalation. The presence of this anion intercalation can effectively inhibit the adsorption of chloride ions on the electrode surface through like-charge repulsion, thereby reducing the corrosion of chloride ions on the catalyst activity. However, the current exploration of the corrosion resistance of catalysts and green, scalable synthesis methods is still insufficient, which makes it difficult to meet the urgent needs of the future development of direct seawater electrolysis technology. Therefore, the development of practical anode catalysts that can efficiently evolve oxygen in seawater environments and have chloride corrosion resistance has become a key direction of current research. Summary of the Invention

[0005] Based on the above background, the purpose of the present invention is to provide a chlorine-corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode and its preparation method and application, which not only has excellent electrocatalytic oxygen evolution performance and stability under alkaline high current conditions, but also exhibits excellent chlorine corrosion resistance in alkaline brine, which is beneficial to the future development of seawater electrolysis.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a chlorine-corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode comprises the following steps:

[0008] (1) After ultrasonic cleaning, the nickel mesh was blown dry in a nitrogen stream to remove oil and oxides on the surface;

[0009] (2) dissolving thiourea in deionized water to obtain a reaction solution, placing the nickel mesh NM in the inner tank of a hydrothermal kettle, adding the pre-mixed thiourea solution dropwise, and heating the hydrothermal kettle to perform a hydrothermal reaction to obtain a nickel sulfide Ni3S2 nanosheet catalyst;

[0010] (3) Sodium chloride NaCl, ferric chloride FeCl3, sodium thiosulfate Na2S2O3 and / or tantalum pentachloride TaCl5 are dissolved in deionized water to prepare an etching solution, the nickel mesh-supported nickel sulfide nanosheets prepared in step (2) are immersed in the etching solution for etching, and the obtained electrode is washed with deionized water and dried by nitrogen N2 to obtain a nickel mesh-supported modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode.

[0011] Furthermore, in step (1), the nickel mesh is ultrasonically cleaned in ethanol, acetone, 1 M hydrochloric acid solution and deionized water for 15 minutes each.

[0012] Furthermore, in step (2), the reaction solution is a 2.5-25 mM thiourea solution.

[0013] Furthermore, in the step (2), the hydrothermal reactor is fully reacted at 100-130°C for 10-14 hours.

[0014] Furthermore, in step (3), the etching solution is a solution containing 1-1.5 M NaCl, 2 mM Na2S2O3, 1 mMFeCl3 and 0-0.02 mM TaCl5.

[0015] Furthermore, in the step (3), the nickel mesh loaded with nickel sulfide nanosheets is etched at 40° C. for 8-15 hours to obtain a chlorine-corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode.

[0016] The present invention also provides a chlorine-corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode prepared by the above preparation method.

[0017] The present invention also provides a chlorine corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode for use in electrocatalytic oxygen evolution reaction and seawater electrolysis to produce hydrogen.

[0018] This study uses a two-step hydrothermal-etching method under mild reaction conditions to construct a hierarchical oxygen evolution electrode composed of sulfide Ni3S2 nanosheets and tantalum-doped iron oxyhydroxide (FeOOH) nanosheet clusters on a nickel mesh substrate. Through the construction of a multi-level interface and heteroatom doping, the electrode not only significantly enhances its intrinsic catalytic activity but also exhibits excellent resistance to chlorine corrosion.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The present invention uses a nickel mesh with high mechanical strength as a substrate and constructs a self-supporting three-dimensional hierarchical structure electrode through in-situ growth. The hydrophilic nanosheet clusters in this structure have pores of different sizes, which helps the effective diffusion of the electrolyte and promotes the rapid release of bubbles when operating at high current density. In addition, the multi-scale pores of the electrode can effectively disperse the voltage and reduce the formation of local hot spots, thereby effectively improving the stability and industrial life of the catalyst.

[0021] (2) The hierarchical structure electrode prepared by the present invention not only provides a large surface area and high-density active sites, but also ensures a strong bonding force between the active material and the substrate, reduces the contact resistance of charge transfer, and ensures rapid mass transfer in the solid-gas-liquid three-phase reaction; at the same time, the local optimization of electron distribution caused by element doping reduces the energy barrier of the catalytic reaction, allowing the electrode to achieve efficient oxygen evolution catalytic reaction at a lower overpotential.

[0022] (3) The chlorine corrosion resistance of the hierarchical oxygen evolution electrode of the present invention is due to the polyatomic SO4 generated by the reconstruction of nickel sulfide in the catalyst intermediate layer. 2- Anion intercalation not only activates the oxygen evolution ability of the FeOOH active layer, but also effectively prevents the anion Cl- Deep corrosion resistance, achieving excellent oxygen evolution stability in seawater. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to fully elaborate on the characteristics, objectives and advantages of the present invention, the specific embodiments of the present invention will be introduced and explained in more detail below in conjunction with the relevant drawings.

[0024] Figure 1 This is a scanning electron microscope image of the catalyst on the electrode surface prepared in Examples 1-4.

[0025] Figure 2 This is the XPS overall spectrum of the electrode surface catalyst prepared in Examples 1-3.

[0026] Figure 3 This is a high-magnification spectrum of the electrode surface catalyst prepared in Example 1-3.

[0027] Figure 4 These are the oxygen evolution polarization curves of the electrodes prepared in Examples 1-3 and a commercial nickel mesh electrode in 1 M KOH solution.

[0028] Figure 5 These are stability test curves of the electrode prepared in Example 1 in 1 M KOH solution and 1 M KOH+0.5 M NaCl solution, respectively. DETAILED DESCRIPTION

[0029] The following will further elaborate on the technical solutions in the embodiments of the present invention with reference to the accompanying drawings. The embodiments described herein are merely illustrative and do not represent all possible implementations of the present invention. The scope of protection of the present invention is not limited to these examples, but has a broader scope of application.

[0030] Example 1

[0031] (1) Cut the nickel mesh into 1×2 cm 2 The small pieces were then ultrasonically cleaned in ethanol, acetone, 1 M hydrochloric acid solution and deionized water for 15 minutes each, and then blown to dryness in a nitrogen stream to remove surface oil and oxides.

[0032] (2) Mix 0.25 mmol of thiourea with 40 mL of deionized water to prepare a 6.25 mM thiourea reaction solution. Place the nickel mesh NM sheet in the inner container of the hydrothermal reactor and slowly add the pre-mixed thiourea solution dropwise to ensure that it evenly covers the entire surface. The hydrothermal reaction is set at 120°C for 12 hours. After cooling, the nickel mesh-supported nickel sulfide Ni3S2 / NM catalyst is obtained.

[0033] (3) Weigh NaCl, FeCl3, Na2S2O3 and TaCl5 to prepare an etching solution with a concentration of 1.25 M NaCl, 2 mM Na2S2O3, 1 mM FeCl3 and 0.1 mM TaCl5. Immerse the nickel mesh loaded with nickel sulfide Ni3S2 / NM catalyst in the etching solution (immersion area of ​​1 × 1 cm 2 ), and etched at a reaction temperature of 40°C for 12 h to obtain a nickel mesh-supported modified iron oxyhydroxide / sulfide Ta-FeOOH / Ni3S2 / NM electrode.

[0034] Example 2

[0035] (1) Cut the nickel mesh into 1×2 cm 2 The small pieces were then ultrasonically cleaned in ethanol, acetone, 1 M hydrochloric acid solution and deionized water for 15 minutes each, and then blown to dryness in a nitrogen stream to remove surface oil and oxides.

[0036] (2) Mix 0.25 mmol of thiourea with 40 mL of deionized water to prepare a 6.25 mM thiourea reaction solution. Place the nickel mesh NM sheet in the inner container of the hydrothermal reactor and slowly add the pre-mixed thiourea solution dropwise to ensure that it evenly covers the entire surface. The hydrothermal reaction is set at 120°C for 12 hours. After cooling, the nickel mesh-supported nickel sulfide Ni3S2 / NM catalyst is obtained.

[0037] (3) Weigh NaCl, FeCl3 and Na2S2O3 to prepare an etching solution with a concentration of 1.25 M NaCl, 2 mM Na2S2O3 and 1 mMFeCl3. Immerse the nickel mesh loaded with nickel sulfide Ni3S2 / NM catalyst in the etching solution (immersion area of ​​1 × 1 cm 2 ), and etched at a reaction temperature of 40°C for 12 hours to obtain a nickel mesh-supported iron oxyhydroxide / sulfide FeOOH / Ni3S2 / NM electrode.

[0038] Example 3

[0039] (1) Cut the nickel mesh into 1×2 cm 2 The small pieces were then ultrasonically cleaned in ethanol, acetone, 1 M hydrochloric acid solution and deionized water for 15 minutes each, and then blown to dryness in a nitrogen stream to remove surface oil and oxides.

[0040] (2) Mix 0.5 mmol of thiourea with 40 mL of deionized water to prepare a 12.5 mM thiourea reaction solution. Place the nickel mesh NM sheet in the inner container of the hydrothermal reactor and slowly add the pre-mixed thiourea solution dropwise to ensure that it evenly covers the entire surface. The hydrothermal reaction is set at 130°C for 10 hours. After cooling, the nickel mesh-supported nickel sulfide Ni3S2 / NM catalyst is obtained.

[0041] Example 4

[0042] (1) Cut the nickel mesh into 1×2 cm 2 The small pieces were then ultrasonically cleaned in ethanol, acetone, 1 M hydrochloric acid solution and deionized water for 15 minutes each, and then blown to dryness in a nitrogen stream to remove surface oil and oxides.

[0043] (2) Mix 0.25 mmol of thiourea with 40 mL of deionized water to prepare a 6.25 mM thiourea reaction solution. Place the nickel mesh NM sheet in the inner container of the hydrothermal reactor and slowly add the pre-mixed thiourea solution dropwise to ensure that it evenly covers the entire surface. The hydrothermal reaction is set at 120°C for 12 hours. After cooling, the nickel mesh-supported nickel sulfide Ni3S2 / NM catalyst is obtained.

[0044] (3) Weigh NaCl, FeCl3, Na2S2O3 and TaCl5 to prepare an etching solution with a concentration of 1.25 M NaCl, 2 mM Na2S2O3, 1 mM FeCl3 and 0.2 mM TaCl5. Immerse the nickel mesh loaded with nickel sulfide Ni3S2 / NM catalyst in the etching solution (immersion area of ​​1 × 1 cm 2 ), and etched at a reaction temperature of 40°C for 12 h to obtain a nickel mesh-supported modified iron oxyhydroxide / sulfide Ta-FeOOH / Ni3S2 / NM electrode.

[0045] The catalysts prepared in Examples 1-4 above were characterized by morphology, structure and chemical properties.

[0046] Figure 1 The scanning electron microscope images of the electrode surface catalysts prepared in Examples 1-4 are shown respectively. Figure 1 In a), Ni3S2 nanosheets are uniformly grown on the nickel mesh substrate. This sheet structure can serve as an active layer and also provide an effective pore structure channel for the rapid diffusion of electrolyte. Example 2 ( Figure 1 In b), thinner and flower-like FeOOH nanosheet clusters can be observed on the surface of Ni3S2 nanosheets. This hierarchical structure not only enhances the interaction between oxyhydroxides and sulfides, but also increases the active surface area, providing more catalytic active sites. Figure 1 In (c), it can be found that the introduction of an appropriate amount of Ta atoms promotes the formation of denser nanosheet clusters. This hierarchical structure can consolidate the interaction between oxyhydroxides and sulfides and provide a larger active surface and more catalytic active sites. Figure 1 In (d), it can be found that excessive Ta atom doping causes the catalyst surface to become rough, and may even lead to a decrease in the mechanical strength of the catalyst and a fragile structure.

[0047] Figure 2 This is the XPS total spectrum of Examples 1-3. Through full spectrum analysis, the presence of Ni, Fe, Ta, O, and S in Example 1, Ni, Fe, O, and S in Example 2, and Ni, O, and S in Example 3 were verified respectively.

[0048] Figure 3 The high-resolution spectrum of Ni 2p at 855.2 eV (Ni 2p 3 / 2 ) and 872.8 eV (Ni 2p 1 / 2 ) corresponds to the two spin-orbit peaks near Ni 2+ . S 2- S 2p 3 / 2 and S 2p 1 / 2 The characteristic peaks of SO4 are located at 161.6 eV and 162.9 eV, while the characteristic peak at 167.4 eV corresponds to SO4 2- SO4 2- The existence of FeOOH is due to surface oxidation, which can effectively activate the FeOOH active layer in the anode reaction of seawater electrolysis and prevent Cl - The aggregation on the hierarchical structure surface improves the electrode's resistance to chloride corrosion. The characteristic peaks of Fe 2p at 711.5 eV and 724.2 eV correspond to Fe 3+ 2p 3 / 2 and Fe 3+ 2p 1 / 2 Comparing the Ni 2p, Fe 2p, and S 2p spectra of Examples 1-3 reveals that with the construction of the hierarchical nanosheet interface and the introduction of Ta, the binding energy of Ni and S shifts toward a negative direction, while Fe 2p shifts toward a higher binding energy. This demonstrates that the synergistic effect of interface optimization coupled with element doping can effectively promote electron transfer and enhance the intrinsic conductivity of the catalyst.

[0049] The electrocatalytic oxygen evolution performance of the electrodes and nickel mesh prepared in Examples 1-3 was tested in a three-electrode system using an electrochemical workstation. 1 M KOH alkaline solution was used as the electrolyte, a graphite rod was used as the counter electrode, and a Hg / HgO electrode was used as the reference electrode. The catalyst prepared in Examples 1-4 had an area of ​​1 cm 2The electrode was used as the working electrode for testing. The potentials of all electrodes were iR compensated and converted to reversible hydrogen electrode (RHE) potentials according to the Nernst equation. The polarization curve scan rate was set to 5 mV s -1 .

[0050] For the oxygen evolution catalyst, the current density is 100 mA cm -2 and 500 mA cm -2 The corresponding overpotential is an important indicator for judging the performance of the catalyst and the feasibility of industrial application. Figure 4 From the polarization curves, we can see that for the commercial nickel mesh electrode (Ni / NM), 100 mA cm -2 The corresponding overpotential is 430 mV. After the nickel sulfide intermediate layer is introduced, the overpotential of Example 3 is reduced. After further multi-level interface optimization, Example 2 shows an excellent overpotential (100 mA cm -2 247 mV; 500 mA cm -2 After introducing the appropriate Ta element to coordinately regulate the electronic structure, Example 1 exhibited the best oxygen evolution performance (100 mA cm -2 230 mV; 500 mA cm -2 is 283 mV).

[0051] In order to test the stability of the oxygen evolution electrode of Example 1 at a high current density, a current density of 500 mA cm-2 was used in a 1 M KOH electrolyte. -2 Furthermore, in order to test the chlorine corrosion resistance of the electrode of Example 1 in seawater, 1 M KOH + 0.5 M NaCl and a current density of 500 mA cm -2 Simulated alkaline seawater electrolysis was carried out under conditions to explore its chlorine corrosion resistance.

[0052] Figure 5 The stability test diagrams of Example 1 in 1 M KOH solution and 1 M KOH + 0.5 M NaCl saline solution were tested at 500 mA cm -2 The results show that Example 1 has good stability under current density of 500 mA cm -2 Driven by current density, the performance did not change significantly in 1 M KOH solution for 360 hours. In 1 M KOH + 0.5 M NaCl saline solution, the voltage of Example 1 did not change significantly after 200 hours.

[0053] It should be understood that the above embodiments are merely examples for clearly illustrating the present invention and are not limited to the above specific implementation methods. Within the framework of the claims, those skilled in the art may adjust or make equivalent transformations to these features and embodiments without changing the essence of the present invention. The specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. All equivalent changes and modifications made in accordance with the scope of protection of the patent application of the present invention shall be deemed to fall within the scope of protection of the present invention.

Claims

1. A method for preparing a chlorine-corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode, characterized in that: The following steps are involved: (1) After ultrasonic cleaning, the nickel mesh was blown dry in a nitrogen stream to remove oil and oxides on the surface; (2) dissolving thiourea in deionized water to obtain a reaction solution, placing a nickel mesh in the inner tank of a hydrothermal kettle, dropping the pre-mixed thiourea solution, heating the hydrothermal kettle for hydrothermal reaction to obtain nickel sulfide Ni3S2 nanosheet catalyst; (3) dissolving sodium chloride, ferric chloride, sodium thiosulfate and tantalum pentachloride in deionized water to prepare an etching solution, immersing the nickel mesh-supported nickel sulfide nanosheets prepared in step (2) in the etching solution for etching, and washing the obtained electrode with deionized water and drying it with nitrogen purge to obtain a nickel mesh-supported modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode; In step (3), the etching solution is a solution containing 1-1.5 M NaCl, 2 mM Na2S2O3, 1 mMFeCl3 and 0.1-0.2 mMTaCl5.

2. The method for preparing a chlorine corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode according to claim 1, characterized in that: In step (1), the nickel mesh was ultrasonically cleaned in ethanol, acetone, 1 M hydrochloric acid solution and deionized water for 15 minutes each.

3. The method for preparing a chlorine corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode according to claim 1, characterized in that: In step (2), the reaction solution is a thiourea solution with a concentration of 2.5-25 mM.

4. The method for preparing a chlorine corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode according to claim 1, characterized in that: In step (2), the hydrothermal reactor is fully reacted at 100-130°C for 10-14 hours.

5. The method for preparing a chlorine corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode according to claim 1, characterized in that: In step (3), the nickel mesh loaded with nickel sulfide nanosheets is etched at 40° C. for 8-15 hours to obtain a modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode that is resistant to chlorine corrosion.

6. A chlorine-corrosion-resistant modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode prepared according to the preparation method according to any one of claims 1 to 5.

7. Use of the modified iron oxyhydroxide / sulfide hierarchical structure oxygen evolution electrode resistant to chlorine corrosion as claimed in claim 6 in electrocatalytic oxygen evolution reaction and hydrogen production by seawater electrolysis.

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