Super-hydrophilic and strong-sulfur-repellent bifunctional catalyst, and preparation method and application thereof
By synthesizing cobalt-molybdenum co-doped iron selenide electrode materials in situ on NF substrates, the problems of low efficiency caused by bubble interference and hydrophobicity of active sites in HER and SOR processes of electrocatalysts were solved, achieving high efficiency and stability of electrocatalysis.
Patent Information
- Application Number
- CN202411911149.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2044-12-24
AI Technical Summary
Existing electrocatalysts suffer from problems such as active sites being easily disturbed by bubbles, low efficiency due to hydrophobicity, and poor stability in HER and SOR processes, especially in alkaline environments.
Cobalt-molybdenum co-doped iron selenide electrode material was synthesized in situ on an NF substrate using a two-step hydrothermal reduction method. The electronic structure was adjusted by the co-doping strategy and combined with hydrophilic surface treatment to prepare a CoMo-Fe3Se4/NF catalyst.
The catalyst's conductivity and stability were improved, enhancing the electrocatalytic activity of the HER and SOR reactions. It also achieved self-cleaning properties and efficient electrolyte wetting, significantly improving catalytic efficiency.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrocatalyst preparation technology, specifically relating to a superhydrophilic and strongly sulfur-repellent bifunctional catalyst, its preparation method, and its application. Background Technology
[0002] Electrocatalytic water splitting for hydrogen production plays an indispensable role in advancing carbon neutrality. However, the slow kinetics of the traditional oxygen evolution reaction (OER) limit the economic efficiency and widespread application of this technology. To address this, researchers have developed a series of novel methods coupling electro-oxidation reactions with the hydrogen evolution reaction (HER). These electro-oxidation reactions, such as biomass oxidation, urea oxidation, and hydrazine oxidation, are not only thermodynamically more favorable, reducing energy requirements, but also generate economically valuable byproducts. Meanwhile, hydrogen sulfide (H2S), a harmful byproduct of petroleum refining and natural gas extraction, is typically absorbed and converted into sulfides in alkaline environments. Notably, H2S is a high-energy substance that is easily oxidized. Based on this characteristic, the efficient collection of hydrogen can be achieved by combining the ultra-low-energy sulfide oxidation reaction (SOR) with the hydrogen evolution reaction (HER).
[0003] Finding high-performance bifunctional catalysts is one of the major challenges currently facing SOR||HER coupling systems. Although noble metal catalysts exhibit excellent electrocatalytic activity, their high cost greatly limits their broad application prospects. In contrast, transition metal selenides, with their unique layered structure, relatively narrow band gap, special morphology, and low cost, have become potential electrocatalysts in the HER and SOR reaction processes. However, in practical applications, they still face many obstacles, including: (1) In the HER process, the large bubbles generated can interfere with charge transport and mass transfer between the solid and liquid interfaces, leading to a gradual weakening of the catalytic activity of selenides; (2) Some catalyst surfaces exhibit extremely strong hydrophobicity, with water contact angles far exceeding 90°, which may be a key factor in their low HER catalytic efficiency in alkaline environments; (3) Prolonged and intense bubble impacts may cause catalyst detachment, especially for powdered catalysts, which will significantly weaken the stability of the electrocatalyst.
[0004] Therefore, by employing multiple strategies to increase the density and conductivity of active sites, the overall performance of catalysts can be significantly improved. Firstly, heteroatom doping, as an effective method for regulating electronic structure, plays a crucial role in enhancing electrocatalytic performance. While single-element doping can improve catalyst activity to some extent, its improvement potential is relatively limited. In contrast, co-doping technology, especially bimetallic co-doping, can reconfigure the electronic structure through synergistic effects, significantly improving the material's conductivity and greatly enhancing its inherent electrocatalytic activity. Furthermore, selecting conductive materials as substrates for catalyst synthesis is an extremely effective way to achieve high-efficiency catalytic performance. Compared to traditional powdered catalysts, monolithic catalysts not only simplify the electrode preparation process but also concentrate active sites by increasing the loading, while eliminating the use of binders, allowing more active sites to directly participate in the reaction. Uniform dispersion of the catalyst on the support helps optimize charge transport efficiency, while the application of hydrophilic surface treatment technology further improves the catalyst's morphology and microstructure, ensuring its firm adhesion to the substrate, thereby significantly improving system stability and electrocatalytic activity. In summary, these two strategies can be used to design catalysts in a targeted manner, and synthesize a bifunctional electrocatalyst with excellent electrocatalytic performance and good hydrophilicity. Summary of the Invention
[0005] To effectively address the aforementioned issues, this invention employs a two-step hydrothermal reduction method to successfully achieve in-situ synthesis of cobalt-molybdenum co-doped iron selenide electrode materials on an NF substrate. This material not only possesses superhydrophilicity and excellent sulfur-repellent properties, but also exhibits significantly enhanced conductivity and inherent electrocatalytic activity through a synergistic regulation strategy involving bimetallic doping, thereby reshaping its electronic structure. Ultimately, we have successfully prepared a bifunctional transition metal selenide catalyst with excellent catalytic activity.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] 1. A superhydrophilic and strongly sulfur-repellent bifunctional catalyst, wherein the structural unit of the catalyst includes a three-dimensional porous NF substrate and a bimetallic co-doped iron selenide active component grown in situ on the substrate; the bimetallic co-doped iron selenide catalyst is specifically CoMo-Fe3Se4 / NF;
[0008] Furthermore, CoMo-Fe3Se4 / NF is obtained by first synthesizing a layered hydroxide precursor CoMoFe-LDF / NF on NF, followed by a hydrothermal selenization process.
[0009] Furthermore, the loading of CoMo-Fe3Se4 on NF was 20–30 mg cm⁻¹. -2 ;
[0010] 2. A method for preparing a superhydrophilic and strongly sulfur-repellent bifunctional catalyst, comprising:
[0011] S1. Synthesis of CoMoFe-LDF / NF precursor: Iron salt, cobalt salt, molybdenum source, urea, and ammonium fluoride are dissolved in deionized water. After stirring, the mixed solution is transferred to a polytetrafluoroethylene container, and pretreated NF is added. The reaction is carried out hydrothermally at 180-230℃ for 5.5-8.5 hours. After the reaction is completed, the mixture is naturally cooled to room temperature. The catalyst is washed 2-3 times with deionized water and anhydrous ethanol, respectively, to obtain the CoMoFe-LDF / NF precursor.
[0012] S2. Synthesis of CoMo-Fe3Se4 / NF: The reducing agent is ultrasonically dissolved in deionized water, and then a selenium source is added. The mixture is stirred until fully dissolved to obtain a mixed solution. The homogeneous mixed solution is transferred to a polytetrafluoroethylene container, and the CoMoFe-LDF / NF precursor synthesized in S1 is added to it. The reaction is carried out hydrothermally at 90-130℃ for 0.5-4.5h. After the reaction is completed, the mixture is naturally cooled to room temperature. The catalyst is washed 2-3 times with deionized water and anhydrous ethanol, respectively, to obtain CoMo-Fe3Se4 / NF.
[0013] In step S1, the pretreatment step of NF is as follows: ultrasonic treatment in 3M HCl solution for 20 to 40 minutes, followed by rinsing three times each with deionized water and anhydrous ethanol, and finally drying the treated sample in a vacuum drying oven at 60°C for subsequent use.
[0014] The molar ratio of molybdenum, cobalt, and iron in molybdenum salts, cobalt salts, and iron salts is 2:4:1 to 6:4:1; further preferred: the molar ratio of iron, cobalt, and molybdenum is 1:4:4; the molar ratio of urea and ammonium fluoride is 1:6 to 1:12; and the molar ratio of iron and urea is 1:3.
[0015] In step S1, the iron salt is one or more of Fe(NO3)2·9H2O, Fe2(SO4)3·9H2O, and FeCl3·6H2O; the cobalt salt is one or more of Co(CH3COO)2·4H2O, Co(NO3)2·6H2O, and CoCl2·6H2O; and the molybdenum source is (NH4)6Mo7O. 24 One or more of the following: ·4H2O, Na2MoO4·2H2O;
[0016] In step S2, the molar ratio of reducing agent to selenium source is 1:1 to 4.5:1; the molar ratio of iron to selenium source is 1:2.7 to 3.0.
[0017] In step S2, the selenium source is one or more of Se, SeO2, and Na2SeO3; the reducing agent is one or more of NaBH4, hydrazine hydrate, ammonia, and urea.
[0018] NF is 1.0cm long, 1.5cm wide, and 0.1cm thick;
[0019] Another objective of this invention is to overcome the limitations of the prior art and propose the application of a superhydrophilic and strongly sulfur-repellent bifunctional catalyst in SOR and HER.
[0020] Beneficial effects of this invention:
[0021] (1) This invention synthesizes a CoMo-Fe3Se4 / NF composite material with superhydrophilicity and strong sulfur-repellent properties on a three-dimensional conductive NF substrate. In the HER process, the continuous and intense bubbles generated tend to adhere to the catalyst surface, which not only hinders charge transport and mass transfer between the solid and liquid interfaces, but may also block active sites and affect catalytic efficiency. However, thanks to the excellent hydrophilicity of CoMo-Fe3Se4 / NF, the wetting degree of the electrolyte on the electrode can be effectively improved, making it easier for hydrogen bubbles to detach from the electrode surface and escape, thereby ensuring a sufficient supply of active sites and significantly improving the efficiency of the HER reaction. At the same time, this invention also has sulfur-repellent properties, which can effectively prevent sulfur elements from adhering to the catalyst surface, thereby achieving the self-cleaning and anti-passivation effects of the electrocatalyst.
[0022] (2) This invention synthesizes a layered hydroxide precursor and then successfully prepares a CoMo-Fe3Se4 / NF composite material using a hydrothermal reduction method. This special structural design can uniformly disperse the active components, making the active sites easier to expose and facilitating full contact between the reaction intermediates and the active sites, thereby improving the electrocatalytic efficiency.
[0023] (3) This invention, through Co and Mo co-doping, generates a strong synergistic effect, increasing the active sites of the catalyst, successfully regulating the electronic configuration of Fe3Se4, and enhancing its intrinsic activity, thereby improving the electrocatalytic performance of HER and SOR reactions. Therefore, Co and Mo co-doping opens up a promising method for developing nickel-based selenide electrocatalysts. Attached Figure Description
[0024] Figure 1 The image shows the XRD pattern of CoMo-Fe3Se4 / NF-1 synthesized in Example 1 of this invention.
[0025] Figure 2 The water contact angle of the CoMo-Fe3Se4 / NF-1 catalyst in Example 1 of this invention ( Figure 2 (a) and sulfur contact angle ( Figure 2 (b) Image.
[0026] Figure 3 The linear sweep voltammetry curves are for the catalysts synthesized in the embodiments and comparative examples of this invention. Figure 3 (a) Linear sweep voltammetric curves of HER for CoMo-Fe3Se4 / NF-1, CoMo-Fe3Se4 / NF-2, CoMo-Fe3Se4 / NF-3, Co-Fe3Se4 / NF, and Fe3Se4 / NF; Figure 3 (b) Linear sweep voltammetric curves of SOR for CoMo-Fe3Se4 / NF-1, CoMo-Fe3Se4 / NF-2, CoMo-Fe3Se4 / NF-3, Co-Fe3Se4 / NF, and Fe3Se4 / NF.
[0027] Figure 4 The two-electrode linear sweep voltammetric curves of the catalyst electrode in the SOR||HER coupling system of Example 4 of this invention are shown. Detailed Implementation
[0028] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the embodiments described in this specification are merely for explaining the invention and are not intended to limit the invention. The parameters, proportions, etc., of the embodiments can be selected according to local conditions without substantially affecting the results.
[0029] Example 1
[0030] Prepare CoMo-Fe3Se4 / NF-1 according to the following steps:
[0031] (1) Pretreatment of NF matrix: The cut NF (1.0cm long, 1.5cm wide, and 0.1cm thick) was immersed in 3M hydrochloric acid solution, sonicated for 30min to remove the oxide film on the surface, rinsed three times with deionized water and anhydrous ethanol, and placed in a vacuum drying oven at 60℃ for later use.
[0032] (2) Synthesis of CoMoFe-LDF / NF precursor: Dissolve 1 mmol Fe(NO3)2·9H2O, 4 mmol Co(NO3)2·6H2O, and 4 mmol Na2MoO4·2H2O in 30.00 mL of deionized water and stir for 30 min until a homogeneous solution is obtained. Then add 182 mg urea and 977.6 mg ammonium fluoride and stir until homogeneous. Transfer the mixed solution to a polytetrafluoroethylene container, add pretreated NF, and perform hydrothermal reaction at 200 °C for 6 h. After the reaction is completed, cool naturally to room temperature and wash the catalyst 2 to 3 times with deionized water and anhydrous ethanol respectively to obtain the CoMoFe-LDF / NF precursor.
[0033] (3) Synthesis of CoMo-Fe3Se4 / NF-1: 264 mg NaBH4 was ultrasonically dissolved in 35.00 mL of deionized water, and then 236.22 mg of selenium powder was added. The mixture was stirred for 30 min to dissolve it completely. The homogeneous solution was transferred to a polytetrafluoroethylene container, and the CoMoFe-LDF / NF precursor synthesized in S1 was added. The mixture was hydrothermally reacted at 120 °C for 2 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The catalyst was washed 2 to 3 times with deionized water and anhydrous ethanol, respectively, to obtain CoMo-Fe3Se4 / NF-1.
[0034] Note: The structure of CoMo-Fe3Se4 / NF-1 in Example 1 was analyzed using X-ray diffraction. Figure 1 As shown, the XRD patterns correspond to the standard card, which fully demonstrates the successful preparation of CoMo-Fe3Se4 / NF-1. Simultaneously, the water contact angle of CoMo-Fe3Se4 / NF-1 was measured. Figure 2 (a)) The water contact angle of CoMo-Fe3Se4 / NF-1 is close to 0°. Water droplets are absorbed as soon as they come into contact with the catalyst surface. CoMo-Fe3Se4 / NF-1 exhibits obvious superhydrophilicity, which is beneficial for the electrolyte to wet the catalyst. This makes it easier for hydrogen bubbles to detach from the electrode surface and escape, ensuring a sufficient supply of active sites and thus enhancing HER activity.
[0035] The method for testing the sulfur contact angle is as follows: First, melt sulfur at 120℃. Simultaneously, fix the sample to be tested on the worktable, ensuring it is horizontal. Then, drop sulfur onto the needle, slowly adjusting the position to allow the sulfur to form a droplet. Next, raise the height of the worktable and slowly move it so that the sample surface and the sulfur droplet gently contact each other. The angle measured at this point is the sulfur contact angle. The testing standard is: a sulfur contact angle greater than 90° indicates sulfur repellency, and less than 90° indicates sulfur affinity. Figure 2(b) is a sulfur contact angle image of CoMo-Fe3Se4 / NF-1 obtained by melting sulfur at 120℃. As can be seen from the figure, the sulfur contact angle of CoMo-Fe3Se4 / NF-1 is 119°, which shows strong sulfur-repellent properties and is beneficial to the catalyst maintaining long-term stability in the SOR process.
[0036] Comparative Example 1
[0037] Prepare Co-Fe3Se4 / NF according to the following steps:
[0038] Preparation of Co-Fe3Se4 / NF catalyst:
[0039] (1) The pretreatment of the NF matrix is the same as in Example 1;
[0040] (2) Synthesis of CoFe-LDF / NF precursor: Dissolve 1 mmol Fe(NO3)2·9H2O and 4 mmol Co(NO3)2·6H2O in 30.00 mL of deionized water and stir for 30 min until a homogeneous solution is obtained. Then add 182 mg urea and 977.6 mg ammonium fluoride and stir until homogeneous. Transfer the mixed solution to a polytetrafluoroethylene container, add the treated NF, and perform a hydrothermal reaction at 200 °C for 6 h. After the reaction is completed, allow it to cool naturally to room temperature. Wash the catalyst 2 to 3 times with deionized water and anhydrous ethanol respectively to obtain the CoFe-LDF / NF precursor.
[0041] (3) Synthesis of Co-Fe3Se4 / NF: 264 mg NaBH4 was ultrasonically dissolved in 35.00 mL of deionized water, and then 236.22 mg selenium powder was added. The mixture was stirred for 30 min to dissolve it completely. The homogeneous solution was transferred to a polytetrafluoroethylene container, and the CoFe-LDF / NF precursor synthesized in S1 was added. The mixture was hydrothermally reacted at 120 °C for 2 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The catalyst was washed 2 to 3 times with deionized water and anhydrous ethanol, respectively, to obtain Co-Fe3Se4 / NF.
[0042] Comparative Example 2
[0043] The Fe3Se4 / NF catalyst was prepared according to the following steps:
[0044] (1) The pretreatment of the NF matrix is the same as in Example 1;
[0045] (2) Synthesis of Fe-LDF / NF precursor: Dissolve 1 mmol Fe(NO3)2·9H2O in 30.00 mL of deionized water and stir for 30 min until a homogeneous solution is obtained. Then add 182 mg urea and 977.6 mg ammonium fluoride to the solution and stir until homogeneous. Transfer the mixed solution to a polytetrafluoroethylene container, add the treated NF, and perform a hydrothermal reaction at 200 °C for 6 h. After the reaction is completed, allow it to cool naturally to room temperature. Wash the catalyst 2 to 3 times with deionized water and anhydrous ethanol respectively to obtain the Fe-LDF / NF precursor.
[0046] (2) Synthesis of Fe3Se4 / NF: 264 mg NaBH4 was ultrasonically dissolved in 35.00 mL of deionized water, and then 236.22 mg of selenium powder was added. The mixture was stirred for 30 min to dissolve it completely. The homogeneous solution was transferred to a polytetrafluoroethylene container, and the Fe-LDF / NF precursor synthesized in S1 was added. The mixture was hydrothermally reacted at 120 °C for 2 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The catalyst was washed 2 to 3 times with deionized water and anhydrous ethanol, respectively, to obtain Fe3Se4 / NF.
[0047] Comparative Example 3
[0048] Mo-Fe3Se4 / NF was prepared according to the following steps:
[0049] (1) The pretreatment of the NF matrix is the same as that in Example 1.
[0050] (2) Synthesis of MoFe-LDF / NF precursor: Dissolve 1 mmol Fe(NO3)2·9H2O and 4 mmol Na2MoO4·2H2O in 30.00 mL of deionized water and stir for 30 min until a homogeneous solution is obtained. Then add 182 mg urea and 977.6 mg ammonium fluoride and stir until homogeneous. Transfer the mixed solution to a polytetrafluoroethylene container, add the treated NF, and perform a hydrothermal reaction at 200 °C for 6 h. After the reaction is completed, allow it to cool naturally to room temperature. Wash the catalyst 2 to 3 times with deionized water and anhydrous ethanol respectively to obtain the MoFe-LDF / NF precursor.
[0051] (3) Synthesis of Mo-Fe3Se4 / NF: 264 mg NaBH4 was ultrasonically dissolved in 35.00 mL of deionized water, and then 236.22 mg of selenium powder was added. The mixture was stirred for 30 min to dissolve it completely. The homogeneous solution was transferred to a polytetrafluoroethylene container, and 3 pieces of the MoFe-LDF / NF precursor synthesized in S1 were added. The reaction was carried out hydrothermally at 120 °C for 2 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The catalyst was washed 2 to 3 times with deionized water and anhydrous ethanol, respectively, to obtain Mo-Fe3Se4 / NF.
[0052] Example 2
[0053] The difference between Example 2 and Example 1 is that step (3) is a hydrothermal reaction at 120°C for 1 hour, while the other operations are the same as in Example 1.
[0054] Prepare CoMo-Fe3Se4 / NF-2 according to the following steps:
[0055] (1) Pretreatment of NF matrix: The cut NF was immersed in 3M hydrochloric acid solution, sonicated for 30 min to remove the oxide film on the surface, rinsed three times with deionized water and anhydrous ethanol, and placed in a vacuum drying oven at 60℃ for later use.
[0056] (2) Synthesis of CoMoFe-LDF / NF precursor: Dissolve 1 mmol Fe(NO3)2·9H2O, 4 mmol Co(NO3)2·6H2O, and 4 mmol Na2MoO4·2H2O in 30.00 mL of deionized water and stir for 30 min until a homogeneous solution is obtained. Then add 182 mg urea and 977.6 mg ammonium fluoride and stir until homogeneous. Transfer the mixed solution to a polytetrafluoroethylene container, add the treated NF, and perform a hydrothermal reaction at 200 °C for 6 h. After the reaction is completed, allow it to cool naturally to room temperature. Wash the catalyst 2 to 3 times with deionized water and anhydrous ethanol respectively to obtain the CoMoFe-LDF / NF precursor.
[0057] (3) Synthesis of CoMo-Fe3Se4 / NF-2: 264 mg NaBH4 was ultrasonically dissolved in 35.00 mL of deionized water, and then 236.22 mg of selenium powder was added. The mixture was stirred for 30 min to dissolve it completely. The homogeneous solution was transferred to a polytetrafluoroethylene container, and the CoMoFe-LDF / NF precursor synthesized in S1 was added. The mixture was hydrothermally reacted at 120 °C for 1 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The catalyst was washed 2 to 3 times with deionized water and anhydrous ethanol, respectively, to obtain CoMo-Fe3Se4 / NF-2.
[0058] Example 3
[0059] The difference between Example 3 and Example 1 is that step (3) is a hydrothermal reaction at 120°C for 3 hours, while the other operations are the same as in Example 1.
[0060] Prepare CoMo-Fe3Se4 / NF-3 according to the following steps:
[0061] (1) Pretreatment of NF matrix: The cut NF was immersed in 3M hydrochloric acid solution, sonicated for 30 min to remove the oxide film on the surface, rinsed three times with deionized water and anhydrous ethanol, and placed in a vacuum drying oven at 60℃ for later use.
[0062] (2) Synthesis of CoMoFe-LDF / NF precursor: Dissolve 1 mmol Fe(NO3)2·9H2O, 4 mmol Co(NO3)2·6H2O, and 4 mmol Na2MoO4·2H2O in 30.00 mL of deionized water and stir for 30 min until a homogeneous solution is obtained. Then add 182 mg urea and 977.6 mg ammonium fluoride and stir until homogeneous. Transfer the mixed solution to a polytetrafluoroethylene container, add the treated NF, and perform a hydrothermal reaction at 200 °C for 6 h. After the reaction is completed, allow it to cool naturally to room temperature. Wash the catalyst 2 to 3 times with deionized water and anhydrous ethanol respectively to obtain the CoMoFe-LDF / NF precursor.
[0063] (3) Synthesis of CoMo-Fe3Se4 / NF-3: 264 mg NaBH4 was ultrasonically dissolved in 35.00 mL of deionized water, and then 236.22 mg of selenium powder was added. The mixture was stirred for 30 min to dissolve it completely. The homogeneous solution was transferred to a polytetrafluoroethylene container, and the CoMoFe-LDF / NF precursor synthesized in S1 was added. The mixture was subjected to hydrothermal reaction at 120 °C for 3 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The catalyst was washed 2 to 3 times with deionized water and anhydrous ethanol, respectively, to obtain CoMo-Fe3Se4 / NF-3.
[0064] Example 4
[0065] The difference between Example 4 and Example 1 is that 4 mmol Co(NO3)2·6H2O is replaced with 3 mmol Na2MoO4·2H2O, while the other operations are the same as in Example 1.
[0066] Prepare CoMo-Fe3Se4 / NF-4 according to the following steps:
[0067] (1) Pretreatment of NF matrix: The cut NF was immersed in 3M hydrochloric acid solution, sonicated for 30 min to remove the oxide film on the surface, rinsed three times with deionized water and anhydrous ethanol, and placed in a vacuum drying oven at 60℃ for later use.
[0068] (2) Synthesis of CoMoFe-LDF / NF precursor: Dissolve 1 mmol Fe(NO3)2·9H2O, 4 mmol Co(NO3)2·6H2O, and 3 mmol Na2MoO4·2H2O in 30.00 mL of deionized water and stir for 30 min until a homogeneous solution is obtained. Then add 182 mg urea and 977.6 mg ammonium fluoride and stir until homogeneous. Transfer the mixed solution to a polytetrafluoroethylene container, add the treated NF, and perform a hydrothermal reaction at 200 °C for 6 h. After the reaction is completed, allow it to cool naturally to room temperature. Wash the catalyst 2 to 3 times with deionized water and anhydrous ethanol respectively to obtain the CoMoFe-LDF / NF precursor.
[0069] (3) Synthesis of CoMo-Fe3Se4 / NF-4: 264 mg NaBH4 was ultrasonically dissolved in 35.00 mL of deionized water, and then 236.22 mg of selenium powder was added. The mixture was stirred for 30 min to dissolve it completely. The homogeneous solution was transferred to a polytetrafluoroethylene container, and the CoMoFe-LDF / NF precursor synthesized in S1 was added. The mixture was hydrothermally reacted at 120 °C for 2 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The catalyst was washed 2 to 3 times with deionized water and anhydrous ethanol, respectively, to obtain CoMo-Fe3Se4 / NF-4.
[0070] Example 5
[0071] The difference between Example 5 and Example 1 is that 4 mmol Co(NO3)2·6H2O is replaced with 5 mmol Na2MoO4·2H2O, while the other operations are the same as in Example 1.
[0072] Prepare CoMo-Fe3Se4 / NF-5 according to the following steps:
[0073] (1) Pretreatment of NF matrix: The cut NF was immersed in 3M hydrochloric acid solution, sonicated for 30 min to remove the oxide film on the surface, rinsed three times with deionized water and anhydrous ethanol, and placed in a vacuum drying oven at 60℃ for later use.
[0074] (2) Synthesis of CoMoFe-LDF / NF precursor: Dissolve 1 mmol Fe(NO3)2·9H2O, 4 mmol Co(NO3)2·6H2O, and 5 mmol Na2MoO4·2H2O in 30.00 mL of deionized water and stir for 30 min until a homogeneous solution is obtained. Then add 182 mg urea and 977.6 mg ammonium fluoride and stir until homogeneous. Transfer the mixed solution to a polytetrafluoroethylene container, add the treated NF, and perform a hydrothermal reaction at 200 °C for 6 h. After the reaction is completed, allow it to cool naturally to room temperature. Wash the catalyst 2 to 3 times with deionized water and anhydrous ethanol respectively to obtain the CoMoFe-LDF / NF precursor.
[0075] (3) Synthesis of CoMo-Fe3Se4 / NF-5: 264 mg NaBH4 was ultrasonically dissolved in 35.00 mL of deionized water, and then 236.22 mg of selenium powder was added. The mixture was stirred for 30 min to dissolve it completely. The homogeneous solution was transferred to a polytetrafluoroethylene container, and the CoMoFe-LDF / NF precursor synthesized in S1 was added. The mixture was hydrothermally reacted at 120 °C for 2 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The catalyst was washed 2 to 3 times with deionized water and anhydrous ethanol, respectively, to obtain CoMo-Fe3Se4 / NF-5.
[0076] Note: Performance evaluation of catalysts HER and SOR: The performance of the catalysts was evaluated using linear sweep voltammetry. A three-electrode system was used. The hydrogen evolution reaction (HER) activity was tested in a 1.0 M NaOH solution, and the SOR activity was tested in a mixed solution containing NaOH and Na₂S (a mixture of 1 mol NaOH and 1 mol Na₂S solid dissolved in 1 L of deionized water). A platinum electrode was used as the counter electrode, Ag / AgCl as the reference electrode, and the catalysts synthesized in the examples and comparative examples as the working electrodes. Linear sweep voltammetry for HER was performed within a voltage range of 1.0–1.6 V (relative to Ag / AgCl) at a scan rate of 5 mV / s, and linear sweep voltammetry for SOR was performed within a voltage range of -0.2–-1.0 V (relative to Ag / AgCl) at a scan rate of 5 mV / s. The results are as follows: Figure 2 (ab) and Table 1 are shown.
[0077] Table 1. Different catalysts at 100 mA·cm -2 Comparison of overpotentials of SOR and HER at current densities
[0078]
[0079] Table 1 shows that single-phase Fe3Se4 / NF exhibits poor electrocatalytic activity. Introducing Co-Fe3Se4 / NF with a single element results in better activity. Introducing a bimetallic element, CoMo-Fe3Se4 / NF-1 shows the best catalytic activity. This is because single doping has certain limitations, while co-doping can improve electrocatalytic performance by adjusting the electronic structure and generating a strong synergistic effect. Simultaneously, the hydrothermal reaction time also significantly affects the catalyst's performance. The results show that CoMo-Fe3Se4 / NF-1 synthesized in the second hydrothermal reaction (2 hours) exhibits the best electrocatalytic activity. Finally, the Mo content also affects the catalyst's performance. The results show that when the Mo content is 4 mmol, the synthesized CoMo-Fe3Se4 / NF-1 exhibits the best electrocatalytic activity. This invention successfully modulates the electronic configuration of Fe3Se4 with Co and Mo elements and enhances its intrinsic activity, opening a promising method for developing iron-based selenide electrocatalysts.
[0080] Example 6
[0081] (1) Performance of the HER||SOR coupling system: CoMo-Fe3Se4 / NF-1 was used as the cathode and anode electrodes of an H-type electrolytic cell, respectively, to construct a two-electrode system for testing. The electrolyte in the cathode chamber was a 1.0M NaOH aqueous solution, and the electrolyte in the anode chamber was a mixed solution formed by dissolving 1 mol NaOH and 1 mol Na2S solid in 1L deionized water. The membrane was a cation exchange membrane (DuPont, Nafion 117), containing Na... + Ion transport provides channels to maintain ion charge balance and delineate the anodic / cathode regions. Linear scan voltammetry is performed at a voltage of 0-2.5V, and the test results are compensated for 90% infrared radiation.
[0082] (2) Performance testing of the HER||OER coupling system: Tests were conducted on a CHI660E electrochemical workstation. The CoMo-Fe3Se4 / NF-1 electrode material obtained in Example 1 was used as the working electrode, and a platinum electrode was used as the counter electrode. The cathode and anolyte were both 1.00M NaOH aqueous solution. The tests were performed in the range of 1.2–2.0 V (relative to Ag / AgCl) at 5 mV·s⁻¹. -1 The linear sweep current-voltage (LSV) curve was tested at a certain sweep speed, and the final LSV curve was obtained by applying 90% impedance compensation.
[0083] illustrate: Figure 4 This is a comparison of the LSVs of the SOR||HER and OER||HER coupled systems in a two-electrode system. The figure shows that at 100 mA cm⁻¹... -2At the given current density, the SOR||HER coupling system requires only 0.676V to achieve the corresponding current density, while the OER||HER system requires 1.719V. This shows that the energy consumption for hydrogen production by the SOR||HER system is much lower than the energy consumption required for hydrogen production by water electrolysis.
[0084] In summary, the CoMo-Fe3Se4 / NF-1 bifunctional catalyst synthesized in this invention exhibits excellent HER and SOR performance and can successfully drive the SOR||HER coupling system, which makes this invention show great potential and development prospects in the fields of hydrogen production and desulfurization.
[0085] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A superhydrophilic and strongly sulfur-repellent bifunctional catalyst, characterized in that: The catalyst includes a three-dimensional porous NF substrate and a bimetallic co-doped iron selenide active component grown in situ on the NF substrate, specifically CoMo-Fe3Se4 / NF; The catalyst is prepared as follows: S1. Synthesis of CoMoFe-LDF / NF precursor: Iron salt, cobalt salt, molybdenum salt, urea, and ammonium fluoride are dissolved in water. After stirring, the mixed solution is transferred to a polytetrafluoroethylene container, and pretreated NF is added. The mixture is then subjected to hydrothermal reaction at 180-230℃ for 5.5-8.5 h. After the reaction is completed, the mixture is cooled and rinsed to obtain the CoMoFe-LDF / NF precursor. The molar ratio of molybdenum, cobalt, and iron in the molybdenum salt, cobalt salt, and iron salt is 2:4:1 to 6:4:
1. The iron salt is Fe(NO3)2·9H2O. S2. Synthesis of CoMo-Fe3Se4 / NF: The reducing agent is ultrasonically dissolved in deionized water, and then a selenium source is added. The mixture is stirred until fully dissolved to obtain a mixed solution. The homogeneous mixed solution is transferred to a polytetrafluoroethylene container, and the CoMoFe-LDF / NF precursor synthesized in S1 is added. The mixture is subjected to hydrothermal reaction at 90-130℃ for 0.5-4.5 h. After the reaction is completed, the mixture is cooled to room temperature and washed to obtain CoMo-Fe3Se4 / NF.
2. The preparation method of the superhydrophilic and strongly sulfur-repellent bifunctional catalyst as described in claim 1, characterized in that: S1. Synthesis of CoMoFe-LDF / NF precursor: Iron salt, cobalt salt, molybdenum salt, urea, and ammonium fluoride are dissolved in water. After stirring, the mixed solution is transferred to a polytetrafluoroethylene container, and pretreated NF is added. The mixture is then subjected to hydrothermal reaction at 180-230℃ for 5.5-8.5 h. After the reaction is completed, the mixture is cooled and rinsed to obtain the CoMoFe-LDF / NF precursor. The molar ratio of molybdenum, cobalt, and iron in the molybdenum salt, cobalt salt, and iron salt is 2:4:1 to 6:4:
1. The iron salt is Fe(NO3)2·9H2O. S2. Synthesis of CoMo-Fe3Se4 / NF: The reducing agent is ultrasonically dissolved in deionized water, and then a selenium source is added. The mixture is stirred until fully dissolved to obtain a mixed solution. The homogeneous mixed solution is transferred to a polytetrafluoroethylene container, and the CoMoFe-LDF / NF precursor synthesized in S1 is added. The mixture is subjected to hydrothermal reaction at 90-130℃ for 0.5-4.5 h. After the reaction is completed, the mixture is cooled to room temperature and washed to obtain CoMo-Fe3Se4 / NF.
3. The preparation method of the superhydrophilic and strongly sulfur-repellent bifunctional catalyst as described in claim 2, characterized in that: In step S1, the pretreatment steps for NF are as follows: the NF substrate is sonicated in HCl solution for 20-40 minutes, then rinsed with deionized water and anhydrous ethanol respectively, and finally, the treated sample is vacuum dried.
4. The preparation method of the superhydrophilic and strongly sulfur-repellent bifunctional catalyst as described in claim 2, characterized in that: The molar ratio of urea to ammonium fluoride is 1:6 to 1:12; the molar ratio of iron to urea is 1:
3.
5. The preparation method of the superhydrophilic and strongly sulfur-repellent bifunctional catalyst as described in claim 2, characterized in that: The molar ratio of iron, cobalt, and molybdenum in the molybdenum salt, cobalt salt, and iron salt is 1:4:
4.
6. The preparation method of the superhydrophilic and strongly sulfur-repellent bifunctional catalyst as described in claim 2, characterized in that: In step S2, the molar ratio of reducing agent to selenium source is 1:1 to 4.5:1; the molar ratio of iron to selenium source is 1:2.7 to 3.
0.
7. The preparation method of the superhydrophilic and strongly sulfur-repellent bifunctional catalyst as described in claim 2, characterized in that: The cobalt salt is one or more of Co(CH3COO)2·4H2O, Co(NO3)2·6H2O, and CoCl2·6H2O; the molybdenum salt is (NH4)6Mo7O. 24 One or more of ·4H2O and Na2MoO4·2H2O.
8. The preparation method of the superhydrophilic and strongly sulfur-repellent bifunctional catalyst as described in claim 2, characterized in that: The selenium source is one or more of Se, SeO2, and Na2SeO3; the reducing agent is one or more of NaBH4, hydrazine hydrate, ammonia, and urea.
9. The application of the superhydrophilic and strongly sulfur-repellent bifunctional catalyst prepared by the method according to any one of claims 2-8, characterized in that, Application of superhydrophilic and sulfur-repellent bifunctional catalysts in electrocatalytic hydrogen evolution reaction and / or electrocatalytic sulfur ion oxidation reaction.