CoSeO3 / NF electrode material for SOR and HER reaction and preparation method thereof

Abstract

The present application relates to the technical field of electrocatalysis, in particular to a CoSeO3 / NF electrode material for SOR and HER reactions and a preparation method thereof.A bifunctional catalyst with SOR and HER electrocatalytic activity is high in overvoltage and poor in catalytic activity.In view of the above technical problems, the present application provides a CoSeO3 / NF electrode material for SOR and HER reactions, which is in-situ synthesized into a catalyst with a urchin-like structure of CoSeO3 microlayer on a three-dimensional porous nickel foam substrate through a simple one-step hydrothermal method.The special structure of the catalyst greatly increases the number of active sites on the catalyst surface and provides more abundant electron transport paths, thereby effectively improving the mass transfer efficiency.The catalyst exhibits high catalytic activity for SOR and HER reactions and has good application prospects in sulfur recovery and efficient hydrogen regeneration.

Description

Technical Field

[0001] This invention relates to the field of electrocatalysis technology, specifically to a CoSeO3 / NF electrode material for SOR and HER reactions and its preparation method. Background Technology

[0002] Sulfur is a valuable commodity with wide applications across various industries, including chemicals, agrochemicals, rubber, cosmetics, fertilizers, and pharmaceuticals. It is also a major precursor to sulfuric acid, considered a crucial chemical in the global economy. However, with the increasing number of pharmaceutical and chemical companies, and the rapid development of industries such as coking, petroleum, and leather tanning, sulfides are widely present in industrial wastewater and exhaust gases. These sulfur-containing wastes cause significant pollution to the atmosphere and water resources, exhibiting not only foul odors, toxicity, and corrosiveness, but also severe impacts on people's lives and industrial production. Therefore, researching and developing technologies for the recycling and utilization of sulfur-containing waste is particularly urgent.

[0003] Currently, the recycling processes for sulfur-containing waste include the following types:

[0004] (1) The Claus process involves recovering acidic gases (H2S and CO2) from acidic feedstocks and processing them in a sulfur recovery unit (SRU) to obtain sulfur. However, Salisu Ibrahim et al. (DOI:10.1016 / j.ces.2017.06.050) found that frequent changes in the composition of acidic gases often lead to lean acidic gases (i.e., a higher proportion of CO2). The flame instability caused by lean acidic gases will damage the feed gas in the Claus furnace, resulting in the need to continuously optimize the amount of fuel gas injected into the Claus furnace, which complicates the process and is not conducive to industrial development.

[0005] (2) The SulFerox process simplifies the Claus unit by directly removing hydrogen sulfide from the gas stream and converting it into sulfur, which greatly reduces operating costs. However, Yunbo Wang et al. (DOI:10.3969 / j.issn.1005-8168.2022.04.001) stated that the sulfur recovery rate of the SulFerox process is low and cannot meet the national standards for SO2 emissions.

[0006] (3) LO-CAT process, which is a liquid phase catalytic oxidation sulfur recovery technology using water as a medium and a renewable iron ion complex catalyst. The process is simple, the desulfurization degree is high, and it meets the environmental protection requirements. However, Xu Fan et al. (Fan, X., Wang, X. P., Li, Z. Q., et al. Research on iron ion loss of LO-CAT sulfur recovery process [J]. Large nitrogen fertilizer, 2023, 46(05): 289-295.) reported that the LO-CAT reagent used in the LO-CAT process had abnormal reduction of iron ion content multiple times, and a large amount of reagent needed to be supplemented centrally. In the actual production process, it cannot be used stably for a long time, causing great economic loss.

[0007] Therefore, various industrialized sulfur recovery methods have their own advantages and disadvantages. In order to further improve the sulfide removal technology, we urgently need to develop a new treatment scheme with simple process, mild reaction conditions, low cost, high efficiency and environmental friendliness.

[0008] In recent years, electrochemical oxidation method has gradually attracted the attention of scholars. Electrochemical oxidation method can simultaneously perform electrochemical sulfur oxidation reaction (SOR) and hydrogen evolution reaction (HER) on sulfur-containing wastewater, which can not only convert S elements in sulfur-containing wastewater into sulfur, but also obtain clean energy hydrogen. However, the dual functional catalyst with SOR and HER electrocatalytic activity has high overpotential and low catalytic activity, which needs to be further improved. SUMMARY

[0009] The existing problems are that the electrode material with SOR and HER electrocatalytic activity has high overpotential and low catalytic activity. In view of the above technical problems, the present application provides a CoSeO3 / NF electrode material for SOR and HER reaction, and the preparation method comprises the following steps:

[0010] (1) removing the oxides and impurities on the surface of the porous nickel foam to obtain a nickel foam carrier;

[0011] (2) adding a Co source and a Se source to deionized water, stirring and dispersing uniformly to obtain a dispersion liquid, adding an ammonium salt to the dispersion liquid to adjust the pH of the solution to 1-3 to obtain a catalyst solution;

[0012] (3) completely immersing the nickel foam carrier obtained in step (1) into the catalyst solution obtained in step (2), and placing it in a high-pressure reaction kettle, and hydrothermal reaction at 80-120℃, after the reaction is completed, the reaction product is washed with deionized water and anhydrous ethanol at least twice, and dried to obtain CoSeO3 / NF.

[0013] Preferably, the Co source in step (2) comprises one or a combination of more than two of Co(NO3)2·6H2O, CoCl2·6H2O, Co(CH3COO)2·4H2O, and CoSO4·7H2O.

[0014] Preferably, the Se source in step (2) comprises one or a combination of more than two of SeO, SeO2, and SeO3.

[0015] Preferably, the molar ratio between the Co source and the Se source in step (2) is 4-7:1, and the mass concentration of the Co source in deionized water is 39-48 g / L.

[0016] Preferably, the pH in step (2) is 3.

[0017] Preferably, the ammonium salt in step (2) comprises one or a combination of more than two of NH4F, NH4Cl, NH4NO3, and NH4HCO3.

[0018] Preferably, the hydrothermal reaction time in step (3) is 5-15 h.

[0019] Preferably, the hydrothermal reaction time in step (3) is 10 h.

[0020] Preferably, step (1) is specifically performed according to the following method:

[0021] The porous nickel foam is sequentially immersed in hydrochloric acid, anhydrous ethanol, and deionized water for ultrasonic cleaning for at least 30 min, and then vacuum dried to obtain a nickel foam carrier.

[0022] Preferably, the concentration of the hydrochloric acid in step (1) is 3 mol / L.

[0023] The present application has the following beneficial effects:

[0024] (1) The present application realizes the sulfur recycling and recovery in the sulfur-containing wastewater at the anode by the electrolysis method, in which the sulfide solution is selectively converted into polysulfide or high-valence polysulfide, and then 0.5M H2SO4 is added to the electrolyte to direct the conversion of the polysulfide into sulfur, so that the sulfur in the sulfur-containing wastewater is recovered at the anode, and the whole process does not produce any waste gas emission, which is a kind of "environment-friendly" desulfurization technology.

[0025] (2) The application synthesizes a sea urchin structure composed of radial micro-sheets in situ on a three-dimensional porous nickel foam (NF) substrate through a simple one-step hydrothermal method, wherein the surface of the micro-sheets is assembled with an array of staggered nanosheets, and the sheet-like structure has a nanoscale conductive network connected to each other, which not only enhances the overall structural stability of the material, but also greatly increases the number of active sites and provides rich material transport paths, thereby effectively improving the mass transfer efficiency. In addition, the structure can efficiently induce the accumulation of negative charges, so that the CoSeO3 / NF electrode material exhibits excellent sulfur oxidation reaction and hydrogen evolution reaction performance, and is suitable for sulfur recovery and efficient hydrogen regeneration process. At the same time, the preparation conditions of CoSeO3 / NF are mild, the cost is low, and the raw materials are easy to obtain, which has good industrial production prospect.

[0026] (3) SeO3 in CoSeO3 2- has a synergistic effect with the transition metal element Co, and SeO3 2- can effectively adjust the electronic state of Co sites, thereby reducing the energy barrier of hydrogen evolution reaction, optimizing the free energy of hydrogen adsorption, making protons (H + ) more easily captured, and thus promoting excellent electrocatalytic activity. In addition, the three-dimensional structure constructed by nanosheets can not only shorten the diffusion path of ions, but also reduce the self-aggregation phenomenon of low-dimensional nanomaterials, which together ensure the stability and high efficiency of the catalyst during long-term use.

[0027] (4) The application finds that, during the preparation of CoSeO3 / NF by the hydrothermal method, the hydrothermal time has a significant effect on the catalytic activity and selectivity of the catalyst. The research results show that, for the preparation process of the application, the performance of CoSeO3 / NF-1 synthesized by low-temperature hydrothermal reaction of CoSeO3 / NF for 10h is better than that of CoSeO3 / NF-2 and CoSeO3 / NF-3 electrode materials synthesized by hydrothermal reaction for 5h and 15h. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 : SEM diagram of CoSeO3 / NF-1.

[0029] Figure 2 : XRD diagram of CoSeO3 / NF-1.

[0030] Figure 3 : Linear sweep voltammetry scan curve diagram of CoSeO3 / NF-1, CoSeO3 / NF-2, CoSeO3 / NF-3, CoSeO3 / NF-4 and CoSe2 / NF-1.

[0031] Figure 4: LSV comparison chart of CoSeO3 / NF-1 in HER||SOR, HER||OER coupling system respectively.

[0032] Figure 5 : Chronoamperometry curve of CoSeO3 / NF-1 in HER||SOR, HER||OER coupling system respectively. DETAILED DESCRIPTION

[0033] The application will be described in detail below with reference to the examples. It should be understood that the following examples are only illustrative of the embodiments of the application, but not a limitation on the scope of the application.

[0034] The foam nickel in the following examples of the application is a porous foam nickel, which is purchased from Xingzhenghong Technology Co., Ltd., and the item number is XZH202201N.

[0035] Example 1

[0036] A CoSeO3 / NF electrode material for SOR and HER reactions, the preparation method is as follows:

[0037] (1) The porous foam nickel is cut into a sample with a thickness of 0.1 cm, a length of 1.5 cm, and a width of 1 cm, and then sequentially immersed in 3 mol / L hydrochloric acid, anhydrous ethanol, and deionized water for ultrasonic cleaning for 30 min, and then vacuum dried to obtain a foam nickel carrier;

[0038] (2) 2.00 g of CoCl2·6H2O and 0.16 g of SeO2 are added to 50 mL of deionized water, stirred and dispersed uniformly to obtain a dispersion liquid, and NH4HCO3 is added to the dispersion liquid to adjust the pH of the solution to 3 to obtain a catalyst solution;

[0039] (3) The foam nickel carrier obtained in step (1) is completely immersed in the catalyst solution obtained in step (2), and placed in a high-pressure reaction kettle, and hydrothermal reaction is carried out at 90℃ for 10 h, after the reaction is completed, it is naturally cooled to room temperature, the reaction product is sequentially washed with deionized water and anhydrous ethanol for 2 times, and finally dried at 60℃ to obtain CoSeO3 / NF-1.

[0040] The CoSeO3 / NF-1 electrode material prepared in this example is characterized by scanning electron microscopy. As shown in the scanning electron micrograph of the CoSeO3 / NF-1 electrode material prepared in this example in the specification Figure 1As shown, after hydrothermal synthesis, the catalyst CoSeO3 / NF-1 presents a unique urchin-like structure, which is composed of radially arranged microscale sheet layers. These microscale sheet layers are decorated with interwoven nanosheet arrays, exhibiting a fine hierarchical structure. This nanonetwork structure can significantly increase the exposure of active sites, thus effectively promoting the electrocatalytic process. In addition, it can be seen that the thickness of the microscale sheet layers is 4 μm.

[0041] As shown in the description accompanying drawings Figure 2 As shown, the XRD pattern of the catalyst CoSeO3 / NF-1 shows that CoSeO3 particles are successfully loaded on the surface of the nickel foam.

[0042] Example 2 is the same as Example 1, except that the hydrothermal time in Example 2 is 5 h. The obtained catalyst is recorded as CoSeO3 / NF-2.

[0043] Example 3 is the same as Example 1, except that the hydrothermal time in Example 3 is 15 h. The obtained catalyst is recorded as CoSeO3 / NF-3.

[0044] Comparative Example 1

[0045] The preparation method of the CoSe2 / NF catalyst is as follows:

[0046] (1) The porous nickel foam was cut into a sample with a thickness of 0.1 cm, a length of 1.5 cm, and a width of 1 cm, and then sequentially immersed in 3 mol / L hydrochloric acid, anhydrous ethanol, and deionized water for ultrasonic cleaning for 30 min, followed by vacuum drying to obtain a nickel foam carrier;

[0047] (2) Synthesis of Co(OH)2 / NF precursor: 50 mL of deionized water was measured in a graduated cylinder and placed in a polytetrafluoroethylene reaction kettle. 2.00 g of CoCl2·6H2O, 0.46 g of NH4F, and 1.21 g of urea were accurately weighed on an analytical balance and placed in the above reaction kettle. A clean magnet was added to stir the solution uniformly. The nickel foam carrier was taken out with tweezers and immersed horizontally in the solution. Then, hydrothermal reaction was carried out at 120°C for 6 h. After the reaction was completed, the catalyst sample was naturally cooled to room temperature. The sample was sequentially washed with deionized water and anhydrous ethanol twice to remove surface residues. Finally, it was dried at 60°C to obtain Co(OH)2 / NF.

[0048] (3) Synthesis of Co(OH)2 / NF precursor: 0.4 g of selenium powder was placed in the upstream of the quartz boat, and the Co(OH)2 / NF obtained in step (2) was placed in the downstream of the quartz boat. The quartz boat was placed in a tube furnace and calcined in air at 450°C for 1 h. It was naturally cooled to room temperature to obtain CoSe2 / NF.

[0049] Comparative Example 2 was the same as Example 1, except that the pH in Comparative Example 2 Step (2) was 5. The catalyst obtained was denoted as CoSeO3 / NF-4.

[0050] Comparative Example 3 was the same as Example 1, except that the hydrothermal temperature in Comparative Example 3 Step (3) was 80°C.

[0051] Comparative Example 4 was the same as Example 1, except that the hydrothermal temperature in Comparative Example 4 Step (3) was 120°C.

[0052] Performance Test

[0053] The performance of the catalysts was evaluated by linear sweep voltammetry using a three-electrode system. The hydrogen evolution reaction (HER) activity was tested in 1.0 M aqueous NaOH solution, and the SOR activity was tested in a mixed solution containing NaOH and Na2S (a mixed solution formed by dissolving 1 mol of NaOH and 1 mol of Na2S solids in 1 L of deionized water). The results are shown in the figures and Table 1. Figure 3 (a corresponds to the linear sweep voltammetry plot of HER, and b corresponds to the linear sweep voltammetry plot of SOR) and Table 1.

[0054] HER reaction: The working electrode was the catalyst obtained in Examples 1-3 and Comparative Examples 1-4, respectively, while a platinum electrode was used as the counter electrode, and Ag / AgCl was used as the reference electrode. Linear sweep voltammetry was performed for HER at a scan rate of 5 mV / s in the voltage range of 1.0-1.6 V (vs. Ag / AgCl).

[0055] SOR reaction: The working electrode was the catalyst obtained in Examples 1-3 and Comparative Examples 1-4, respectively, while a platinum electrode was used as the counter electrode, and Ag / AgCl was used as the reference electrode. Linear sweep voltammetry was performed for SOR at a scan rate of 5 mV / s in the voltage range of -0.2-1.0 V (vs. Ag / AgCl).

[0056] Table 1

[0057]

[0058] From Table 1, the hydrogen evolution and sulfur oxidation reaction performance of CoSeO3 / NF is far superior to that of CoSe2 / NF, because compared with CoSe2, the urchin-like morphology assembled by nanosheet arrays of CoSeO3 / NF can maximize the exposure of active sites, significantly enhance the electronic conductivity, maximize the hydrogen evolution adsorption energy, and improve the charge transfer capability, thereby exhibiting excellent electrochemical activity. At the same time, the reaction time, the pH and temperature of the reaction also have a great influence on the performance of the catalyst, and the performance of CoSeO3 / NF-1 synthesized by low-temperature hydrothermal reaction for 10h is superior to that of CoSeO3 / NF-2 and CoSeO3 / NF-3 electrode materials synthesized by hydrothermal reaction for 5h and 15h, and the performance of CoSeO3 / NF-1 synthesized at pH = 3 is also superior to that of CoSeO3 / NF-4 synthesized at pH = 5, and compared with the hydrothermal reaction temperature of 80℃ and 120℃, the CoSeO3 / NF-1 synthesized by setting the reaction temperature to 90℃ exhibits better catalytic performance. In summary, the CoSeO3 / NF-1 electrode material synthesized by the application exhibits more significant advantages in the field of hydrogen regeneration and integrated recovery of sulfur.

[0059] Application Example 1

[0060] (1) Performance of HER||SOR coupling system: CoSeO3 / NF-1 was used as the cathode electrode and anode electrode of the H-type electrolytic cell, respectively, to construct a two-electrode system for testing. The cathode chamber electrolyte was 1.0M NaOH aqueous solution, the anode chamber electrolyte was a mixed solution formed by dissolving 1mol NaOH and 1mol Na2S solids in 1L deionized water, and the separator was a cation membrane (DUPONT, Nafion 117) which provided a channel for the transport of Na+ ions to maintain ionic charge balance and divide the anode / cathode area. Linear sweep voltammetry test was carried out at a voltage of 0-2.5V, and the test results were compensated by 90% infrared. +

[0061] (2) Performance of HER||OER coupling system: The test was carried out on CHI660E electrochemical workstation, and CoSeO3 / NF-1 electrode material obtained in Example 1 was used as the working electrode, and platinum electrode was used as the counter electrode. The cathode and anode electrolyte were both 1.00M NaOH aqueous solution. Linear sweep voltammetry (LSV) curve test was carried out at a scan rate of 5mV·s -1

[0062] Description Figure 4 ​​(a) is the LSV test comparison chart of HER||SOR and HER||OER coupling system, the results show that at the current density of 100 mA cm-2, the HER||SOR coupling system only needs 0.624 V voltage to reach the corresponding current density, while the HER||OER system needs 1.722 V voltage, and the energy consumption is much higher than that of the HER||SOR system. -2 -2 S S -1 -1 Therefore, it can be seen that the CoSeO3 / NF-1 can successfully prepare sulfur from sulfur-containing wastewater.

[0063] (3) Sulfur oxidation recovery and sulfur Faraday efficiency: i-t test was carried out on the HER||SOR double electrode system under the application of 100 mA·cm-2current density, and then 0.5 M H2SO4 aqueous solution was added to the electrolyte in the anode chamber after the reaction, so that the pH of the electrolyte was 1, and sulfur was obtained, and the Faraday efficiency (FE) of sulfur was calculated according to the recovery mass of sulfur, and the Faraday efficiency of HER||SOR is shown in the accompanying drawings of the specification. Figure 4

[0064] Application Example 2

[0065] Catalytic activity stability test: the test was carried out by chronoamperometry (i-t), and the results are shown in the accompanying drawings of the specification, and the working current of-0.1 A and 0.1 A was applied to two identical CoSeO3 / NF-1 respectively, and the electrolyte was replaced every 24 h, and the catalytic activity stability of the catalyst in the HER and SOR reaction processes was tested respectively. Figure 5

[0066] Figure 5 (a) is the catalytic activity stability of CoSeO3 / NF-1 in the HER reaction process, Figure 5 (b) is the catalytic activity stability of CoSeO3 / NF-1 in the SOR reaction process. The results show that after each continuous operation for 24 h, the current density of CoSeO3 / NF-1 shows a downward trend, but the current density is recovered after replacing the electrolyte, and after 240 h of durability test, the current density generated by CoSeO3 / NF-1 in the HER and SOR reaction processes does not show obvious attenuation, which proves that CoSeO3 / NF-1 has excellent electrocatalytic durability.

[0067] ​​​​​​​In summary, the CoSeO3 / NF-1 bifunctional catalyst obtained by the application has significant advantages in hydrogen regeneration and integrated recovery of sulfur, which not only helps to more accurately regulate the supply and demand balance of sulfur, but also provides new possibilities for promoting sustainable development.

[0068] The above is based on the ideal embodiment of the application, and the above description can be varied and modified without deviating from the technical idea of the application. The technical scope of the application is not limited to the content of the specification, and must be determined by the scope of the claims.

Claims

1. A CoSeO3 / NF electrode material for SOR and HER reactions in a HER||SOR coupling system, characterized in that, The preparation method of the CoSeO3 / NF electrode material comprises the following steps: (1) removing oxides and impurities on the surface of the porous nickel foam to obtain a nickel foam carrier; (2) adding a Co source and a Se source into deionized water, stirring and uniformly dispersing to obtain a dispersion liquid, adding an ammonium salt into the dispersion liquid to adjust the pH of the solution to 1-3, and obtaining a catalyst solution; (3) completely immersing the nickel foam carrier obtained in step (1) into the catalyst solution obtained in step (2), placing the catalyst solution into a high-pressure reaction kettle, and performing hydrothermal reaction at 80-120℃, after the reaction is completed, washing the reaction product with deionized water and anhydrous ethanol for at least 2 times in sequence, and drying to obtain CoSeO3 / NF; The Co source in step (2) comprises one or more than two combinations of Co(NO3)2·6H2O, CoCl2·6H2O, Co(CH3COO)2·4H2O and CoSO4·7H2O; The Se source in step (2) comprises one or more than two combinations of SeO, SeO2 and SeO3; The molar ratio between the Co source and the Se source in step (2) is 4-7:1, and the mass concentration of the Co source in the deionized water is 39-48g / L; The ammonium salt in step (2) comprises one or more than two combinations of NH4F, NH4Cl, NH4NO3 and NH4HCO3; The hydrothermal reaction time in step (3) is 5-15h.

2. The CoSeO3 / NF electrode material for SOR and HER according to claim 1 is applied in a HER||SOR coupling system, characterized in that, The pH in step (2) is 3.

3. The CoSeO3 / NF electrode material for SOR and HER according to claim 1 in a HER||SOR coupling system, characterized in that, The hydrothermal reaction time in step (3) is 10h.

4. The CoSeO3 / NF electrode material for SOR and HER according to claim 1 in an HER||SOR coupling system, characterized in that, Step (1) is specifically performed as follows: The porous nickel foam is sequentially immersed into hydrochloric acid, anhydrous ethanol and deionized water for ultrasonic cleaning for at least 30min, and then vacuum drying is performed to obtain the nickel foam carrier.

5. The CoSeO3 / NF electrode material for SOR and HER according to claim 4 is applied in a HER||SOR coupling system, characterized in that, The concentration of the hydrochloric acid in step (1) is 3mol / L.

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