Sulfur-hydrophobic self-cleaning porous nanosheet array electrocatalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of electrocatalytic materials and clean energy, and discloses a sulfur-hydrophobic self-cleaning porous nanosheet array electrocatalyst as well as a preparation method and application thereof. The method comprises the following steps: (1) substrate pretreatment: carrying out ultrasonic cleaning on ferrocobalt foam by using acetone, ethanol and deionized water in sequence, blow-drying, and carrying out double-sided etching treatment by using a DBD plasma technology to obtain a PCFF; (2) electro-deposition of a copper layer: performing constant-potential electro-deposition of copper on the surface of the PCFF to obtain a CuCoFe / PCFF alloy precursor; and (3) hydrothermal vulcanization: performing vulcanization treatment on the CuCoFe / PCFF alloy precursor in a hydrothermal environment containing a sulfur source to obtain the CuCoFeS / PCFF electrode. The problems that an SOR electrode is prone to being passivated by sulfur and short in service life are solved, the low-cost and high-activity non-noble metal electrode preparation method is provided, and an electrode structure which can still keep stability under high current density is achieved.

Description

Technical Field

[0001] This invention relates to the fields of electrocatalytic materials and clean energy technology, and more specifically to a method for preparing a sulfur-repellent self-cleaning electrode for sulfur oxidation reaction (SOR), and the application of the electrode in a coupling system for hydrogen production by water electrolysis, sulfur-containing wastewater treatment and seawater desalination. Background Technology

[0002] Traditional water electrolysis for hydrogen production is limited by the high overpotential of the oxygen evolution reaction (OER) at the anolyte and its dependence on freshwater resources. Furthermore, seawater electrolysis suffers from problems such as the chlorination oxidation reaction (CIOR). In recent years, to reduce energy consumption and achieve the resource-based conversion of sulfur pollutants, sulfur oxidation reaction (SOR)-assisted electrolysis for hydrogen production has been developed. However, during the SOR process, sulfur intermediates easily deposit on the electrode surface and form a passivation layer, leading to deactivation of active sites and a decline in electrode performance. While some sulfur-resistant catalysts have been studied, they generally suffer from insufficient sulfur-repellent properties, complex preparation processes, and poor long-term stability. Specifically:

[0003] 1. Existing electrodes used for SOR are susceptible to passivation due to sulfur species deposition, resulting in rapid activity decay and short service life; 2. Existing electrode preparation methods mostly rely on precious metals or complex multi-step synthesis, which are costly and cumbersome. 3. Existing catalysts lack stability at high current densities, making it difficult to meet the requirements of industrial applications; 4. There is a lack of three-dimensional porous self-supporting electrodes that combine high activity, high sulfur repellency, and structural stability.

[0004] Therefore, developing a sulfur-repellent catalyst with good sulfur-repellent properties, simple process, and long life is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a sulfur-repellent self-cleaning porous nanosheet array electrocatalyst, its preparation method and application, which solves the problems of SOR electrode being easily passivated by sulfur and having a short lifespan, provides a low-cost, high-activity non-noble metal electrode preparation method, and realizes an electrode structure that can still maintain stability under high current density.

[0006] One objective of this invention is to provide a method for preparing a sulfur-repellent, self-cleaning porous nanosheet array electrocatalyst, the specific steps of which are as follows: (1) Substrate pretreatment: The cut cobalt-iron foam (Co:Fe=8:2) was ultrasonically cleaned with acetone, ethanol and deionized water in sequence, dried and then subjected to double-sided etching treatment by DBD plasma technology to obtain plasma-etched cobalt-iron foam (PCFF). (2) Electrodeposited copper layer: Copper is electrodeposited on the PCFF surface at a constant potential to obtain CuCoFe / PCFF alloy precursor; (3) Hydrothermal sulfidation: The CuCoFe / PCFF alloy precursor is subjected to sulfidation treatment in a hydrothermal environment containing sulfur source (0.1M Na2S·9H2O) to obtain CuCoFeS / PCFF electrode.

[0007] Preferably, in step (1), the double-sided etching process is performed by treating both sides of the cobalt-iron foam with a power of 60 W for 5-25 minutes.

[0008] Preferably, in step (2), the constant potential electrodeposition of copper is performed as follows: using PCFF as the working electrode, Hg / Hg2Cl2 as the reference electrode, and platinum wire as the counter electrode, constant potential electrodeposition is carried out in CuCl2·2H2O solution to obtain CuCoFe / PCFF precursor, which is then washed and dried.

[0009] Preferably, the concentration of the CuCl2·2H2O solution is 0.5 mol / L, and the constant potential electrodeposition is performed at -1.2 V for 5-20 s.

[0010] Preferably, in step (3), the sulfidation treatment is: hydrothermal reaction at 120℃-180℃ for 6 h in 0.1 mol / L Na2S solution.

[0011] Furthermore, it also includes post-processing: the multi-sulfide CuCoFeS / PCFF electrode is washed with ethanol and deionized water and dried at low temperature, so that it can be used as a self-supporting electrode.

[0012] Furthermore, the CuCoFeS / PCFF electrode may optionally be loaded with platinum (for the cathode): To improve the hydrogen evolution performance of the cathode, the CuCoFeS / PCFF electrode was immersed in a 1.0 g / L chloroplatinic acid (H2PtCl6) solution for 3 h, and after washing and drying, a Pt-CuCoFeS / PCFF composite electrode was obtained.

[0013] The second objective of this invention is to provide a sulfur-repellent, self-cleaning porous nanosheet array electrocatalyst.

[0014] The third objective of this invention is to provide an application of a sulfur-repellent, self-cleaning porous nanosheet array electrocatalyst, which can be used for: 1. A sulfur oxidation reaction (SOR) electrocatalyst that efficiently converts sulfur-containing pollutants into elemental sulfur; 2. Anode material for low-power water electrolysis hydrogen production systems, which can replace traditional OER electrodes; 3. Chlorine-resistant and sulfur-resistant passivation electrodes in seawater electrolysis hydrogen production systems for efficient hydrogen production; 4. In an integrated system that couples hydrogen production with sulfur-containing wastewater treatment.

[0015] As can be seen from the above technical solution, compared with the prior art, the technical effects achieved by the present invention are as follows: 1. Solved the problem of SOR electrode being susceptible to sulfur passivation and having a short lifespan: By constructing a sulfur-repellent surface (contact angle 129°) and a three-dimensional porous structure, the deposition of sulfur species was effectively suppressed.

[0016] 2. A low-cost, high-activity non-precious metal electrode preparation method is provided: using an inexpensive cobalt-iron foam substrate, combined with a simple electrodeposition-hydrothermal method, avoiding precious metals and complex processes.

[0017] 3. An electrode structure that maintains stability under high current density has been achieved: The self-supporting integrated design and robust interface bonding ensure the mechanical and electrochemical stability of the electrode under high current conditions. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 This is a scanning electron microscope (SEM) image of the CuCoFeS / PCFF catalyst in Example 1.

[0020] Figure 2 The contact angle between the CuCoFeS / PCFF catalyst and the CFF substrate in Example 1 is shown.

[0021] Figure 3 The X-ray diffraction (XRD) pattern of the sulfur product in Example 1 is shown.

[0022] Figure 4 The figures show the catalytic activity of CuCoFeS / PCFF and the comparative catalyst, where a is a comparison of linear sweep voltammetry curves, b is a comparison of catalyst current densities at different potentials, c is the corresponding Tafel slope graph, and d is the corresponding electrochemical impedance spectroscopy graph.

[0023] Figure 5 The graph shows the stability of CuCoFeS / PCFF, where a is 100 mA cm⁻¹. -2 Chronocurrent test plot at current density, b is 500 mA cm⁻¹ -2 Chronocurrent test plot at current density, c = 1000 mA cm⁻¹ -2 Graph of chronocurrent test at current density.

[0024] Figure 6 This is a comparison chart of energy consumption between HER||SOR and HER||OER.

[0025] Figure 7 The graph shows the effect of DBD treatment time on catalyst performance in Example 2, where a is the linear sweep voltammetry curve for different DBD times, b is the corresponding Tafel slope graph, and c is the corresponding electrochemical impedance spectroscopy graph.

[0026] Figure 8 The graph shows the effect of electrodeposition time on catalyst performance in Example 3, where a is the linear sweep voltammetry curve for different electrodeposition times, b is the corresponding Tafel slope graph, and c is the corresponding electrochemical impedance spectroscopy graph.

[0027] Figure 9 The graph shows the effect of hydrothermal temperature on the catalyst performance in Example 4, where a is the linear sweep voltammetry curve at different hydrothermal temperatures, b is the corresponding Tafel slope graph, and c is the corresponding electrochemical impedance spectroscopy graph. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: A method for preparing a sulfur-repellent, self-cleaning porous nanosheet array electrocatalyst 1. Pretreatment: After cutting the cobalt-iron foam, it was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water for 10 minutes each, dried, and placed in a DBD plasma device. Both sides of the foam were treated with 60W power (40V, 1.5A) for 20 minutes each to obtain PCFF. SEM characterization showed that the treated surface formed a large number of microcracks and pores, significantly enhancing the specific surface area and bonding sites.

[0030] 2. Electrodeposition of copper: Using the treated polycarbonate foam (PCFF) as the working electrode, Hg / Hg2Cl2 as the reference electrode, and platinum wire as the counter electrode, a constant potential (-1.2 V vs. Hg / Hg2Cl2) electrodeposition was performed for 10 seconds in a 0.5 mol / L CuCl2·2H2O solution to form a CuCoFe / PCFF precursor, which was then washed and dried.

[0031] 3. Hydrothermal sulfidation: The precursor and 0.1 mol / L Na₂S solution were placed in an autoclave and hydrothermally reacted at 120°C for 6 hours. After natural cooling, a CuCoFeS / PCFF electrode was obtained, forming a three-dimensional porous nanoflower-like multi-element sulfide (CuCoFeS / PCFF) structure, as shown below. Figure 1 As shown.

[0032] Performance testing: 1. Sulfur-repellent surface design (excellent sulfur-repellent self-cleaning performance): Using molten sulfur powder as test droplets, the sulfur contact angle on the surfaces of different catalysts was measured. The sulfur contact angle test results show (e.g.) Figure 2 The CuCoFeS / PCFF electrode exhibits a sulfur contact angle as high as 129°, while the unmodified cobalt-iron foam substrate has a contact angle of only 61°, demonstrating its excellent sulfur-repellent ability and its ability to physically inhibit the formation of passivation layers.

[0033] This high sulfur-repellent property can effectively inhibit the excessive adsorption and deposition of polysulfide intermediates on the electrode surface, which is the key to achieving the self-cleaning function.

[0034] 2. Integrated structure: The electrode is a self-supporting structure that does not require adhesives. The active layer is firmly bonded to the substrate, making it suitable for high current density operation.

[0035] 3. High activity and stability: Activity: 100 mA·cm⁻¹ in a 1 M Na₂S + 1 M NaOH electrolyte. -2 The current density requires only a 0.295 V overpotential, and the Tafel slope is 30 mV·dec. -1 It has a charge transfer resistance as low as 0.182 Ω, which is superior to the noble metal RuO2 benchmark catalyst.

[0036] See Figure 4 Using a standard three-electrode system, in a solution containing 1 mol L... -1 1 mol L of Na2S -1 The tests were conducted in NaOH electrolyte. Figure a shows the linear sweep voltammetry curves after iR compensation, indicating that CuCoFeS / PCFF exhibits better SOR activity, outperforming the prepared CuCoFeS / CFF, CuCoS / PCF, CuFeS / PFF, RuO2 / CFF, and the original CFF. Specifically, CuCoFeS / CFF achieves 100 mA cm⁻¹ at an overpotential of only 0.295 V vs. RHE. -2 The current density is significantly higher than that of noble metal RuO2 / CFF (0.301 V vs. RHE) and CFF (0.613 V vs. RHE).

[0037] Figure b shows a comparison of the specific current densities that the catalyst can achieve at different potentials, indicating that the CuCoFeS / PCFF catalyst can operate at high current densities, laying the foundation for industrial applications.

[0038] Figure c shows that the Tafel slope of CuCoFeS / PCFF is the smallest (30mV dec). -1 This indicates that it has superior electrocatalytic reaction kinetics.

[0039] As shown in Figure d, CuCoFeS / PCFF has the lowest charge transfer resistance (Rct = 0.182 Ω), which indicates that the material has a higher charge transfer rate during electrocatalysis.

[0040] Stability: To verify the long-term operational stability of the catalyst, continuous chronoamperometry was performed in a standard three-electrode system with a 1 mol L⁻¹ electrolyte. -1 NaOH + 2 mol L -1 Na2S.

[0041] See Figure 5 Figure a shows the CuCoFeS / PCFF electrode at 100 mA·cm⁻¹ -2 After continuous operation for over 300 hours, Figure b shows the CuCoFeS / PCFF electrode at 500 mA·cm⁻¹. -2 After continuous operation for over 400 hours, Figure c shows the CuCoFeS / PCFF electrode at 1000 mA·cm⁻¹. -2 The catalyst operated continuously for over 200 hours. After replacing the electrolyte periodically, the current density quickly recovered to its original level, indicating that the catalyst bulk structure remained intact and its performance remained stable. After 5000 CV cycles, the LSV curves almost overlapped. Characterization by SEM, XRD, and XPS showed that the catalyst bulk structure remained intact after the reaction.

[0042] 4. Low-energy hydrogen production: A HER||SOR coupling system is constructed by combining CuCoFeS / PCFF (anode) and Pt-CuCoFeS / PCFF (cathode), requiring only 1.252 V cell voltage to achieve 1000 mA·cm⁻¹ hydrogen production. -2 Its high current density is far lower than that of the traditional HER||OER system (2.335 V). See Figure 6 Energy consumption calculations show that at 1000 mA·cm -2 The high current density production of 1 kg of hydrogen consumes only 2.99 kW·h of electricity, which is 46.4% lower than that of the traditional system.

[0043] 5. Seawater adaptability: The coupling system operates well in alkaline seawater. The low potential advantage of SOR effectively avoids the occurrence of chlorine oxidation side reaction (CLOR), and achieves stable hydrogen production resistant to chlorine corrosion.

[0044] 6. Simple preparation process: The three-step method of "plasma etching + electrodeposition + hydrothermal sulfidation" is adopted. The process is simple, does not require precious metals or complex equipment, and is suitable for large-scale preparation.

[0045] 7. Resource recovery of sulfur products: After electrolysis, acidification of the anolyte (e.g., adding concentrated H2SO4 to pH=1) can recover elemental sulfur powder, which XRD confirms as S8 (e.g., ...). Figure 3 This has enabled the resource-based transformation of sulfur pollutants.

[0046] Example 2 optimizes the DBD processing conditions (60W power, 20min time). The remaining operating conditions are the same as in Example 1.

[0047] See Figure 7 The electrolyte used is 1 mol L. -1 NaOH + 1 mol L -1 Using a standard three-electrode system of Na₂S, the SOR performance of the catalyst was tested under different DBD (degradation by dispersive oxidation) times. Comparative experiments showed that increasing the treatment time from 5 min to 25 min resulted in a performance level of 100 mA·cm⁻¹. -2 The overpotential gradually decreased (from 543 mV to 486 mV and then to 446 mV). Although the sample treated for 25 min showed good performance at j... 100 The sample treated for 20 min exhibited the lowest overpotential, but the sample treated for 20 min showed the smallest Tafel slope (43 mV·dec). -1 It also exhibits lower charge transfer resistance. Furthermore, electrodeposition of copper on catalysts treated with different DBD times revealed that samples treated with DBD for 20 min showed higher copper deposition rates. 100 The lowest overpotential was observed (301 mV). Considering both kinetics and energy consumption, 20 min was the optimal time.

[0048] Example 3 optimizes electrodeposition conditions (-1.2V vs. Hg / Hg2Cl2, deposition time 10s). The remaining operating conditions are the same as in Example 1.

[0049] See Figure 8 The electrolyte used is 1 mol L. -1 NaOH + 1 mol L -1 Using a standard three-electrode system of Na2S, the SOR performance of catalysts treated with different electrodeposition times was tested. Optimization experiments with deposition time showed that samples deposited for 10 s and 15 s exhibited better performance in terms of deposition time.100 The overpotentials were similar (~301 mV), but the Tafel slope of the 10s sample was (69 mV·dec). -1 The nanoflower structure formed at a deposition voltage of -1.2V is more uniform and open than the thick stacked structure formed at -1.35V and -1.5V.

[0050] Example 4 optimized the hydrothermal conditions (120℃, reaction time 6h, Na2S concentration 0.1M). The remaining operating conditions are the same as in Example 1.

[0051] See Figure 9 The electrolyte used is 1 mol L. -1 NaOH + 1 mol L -1 The SOR performance of catalysts prepared under different hydrothermal temperatures using a standard three-electrode system of Na2S was tested. System optimization results showed that the catalyst prepared under these conditions had the lowest overpotential (295 mV @ j). 100 ) and the minimum Tafel slope (30 mV·dec) -1 Excessive temperature (150℃, 180℃) or prolonged time (9h) both lead to performance degradation. Optimized sulfur source concentration showed that 0.1M yielded the best performance; excessively high concentrations may affect morphology and kinetics.

[0052] The electrode of this invention can also serve as a bifunctional electrode for sulfur oxidation and hydrogen evolution reactions, constructing membrane-free or membrane electrode assembly (MEA) systems. An MEA device has been experimentally constructed at 1 A·cm⁻¹. -2 It ran stably for 144 hours.

[0053] This invention can be extended to other transition metal sulfide systems, such as preparing CuCoNiS, CuFeMnS and other multi-component sulfides by adjusting the metal salt in the electrodeposition or sulfidation steps, all of which are within the scope of protection of this invention.

[0054] The electrode of this invention is suitable for continuous flow electrolyzer systems and can be coupled with renewable energy sources such as photovoltaic and wind power to achieve simultaneous recovery of green hydrogen and sulfur resources.

[0055] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a sulfur-repellent, self-cleaning porous nanosheet array electrocatalyst, characterized in that, The specific steps are as follows: (1) Substrate pretreatment: Cobalt iron foam was ultrasonically cleaned with acetone, ethanol and deionized water in sequence, dried and then etched on both sides by DBD plasma technology to obtain PCFF; (2) Electrodeposited copper layer: Copper is electrodeposited on the PCFF surface at a constant potential to obtain CuCoFe / PCFF alloy precursor; (3) Hydrothermal sulfidation: The CuCoFe / PCFF alloy precursor is sulfided in a hydrothermal environment containing a sulfur source to obtain CuCoFeS / PCFF electrode.

2. The method for preparing a sulfur-repellent self-cleaning porous nanosheet array electrocatalyst according to claim 1, characterized in that, In step (1), the double-sided etching process is performed by treating both sides of the cobalt-iron foam with a power of 60 W for 5-25 minutes.

3. The method for preparing a sulfur-repellent self-cleaning porous nanosheet array electrocatalyst according to claim 1, characterized in that, In step (2), the constant potential electrodeposition of copper is performed as follows: using PCFF as the working electrode, Hg / Hg2Cl2 as the reference electrode, and platinum wire as the counter electrode, constant potential electrodeposition is carried out in CuCl2·2H2O solution to obtain CuCoFe / PCFF precursor.

4. The method for preparing a sulfur-repellent self-cleaning porous nanosheet array electrocatalyst according to claim 3, characterized in that, The concentration of the CuCl2·2H2O solution is 0.5 mol / L, and the constant potential electrodeposition is performed at -1.2 V for 5-20 s.

5. The method for preparing a sulfur-repellent self-cleaning porous nanosheet array electrocatalyst according to claim 1, characterized in that, In step (3), the sulfidation treatment is carried out by hydrothermal reaction at 120℃-180℃ for 6 h in a 0.1 mol / L Na2S solution.

6. The method for preparing a sulfur-repellent self-cleaning porous nanosheet array electrocatalyst according to claim 1, characterized in that, It also includes post-processing: the CuCoFeS / PCFF electrode is washed with ethanol and deionized water and dried at low temperature.

7. The method for preparing a sulfur-repellent self-cleaning porous nanosheet array electrocatalyst according to claim 1, characterized in that, It also includes platinum loading: the CuCoFeS / PCFF electrode is immersed in chloroplatinic acid solution, washed and dried to obtain a Pt-CuCoFeS / PCFF composite electrode.

8. The method for preparing a sulfur-repellent self-cleaning porous nanosheet array electrocatalyst according to claim 7, characterized in that, The concentration of the chloroplatinic acid solution is 1.0 g / L, and the immersion time is 3 hours.

9. The sulfur-repellent self-cleaning porous nanosheet array electrocatalyst obtained by any one of the preparation methods described in claims 1-8.

10. The application of the sulfur-repellent self-cleaning porous nanosheet array electrocatalyst according to claim 9.

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