A metal-oxo acid modified transition metal hydroxide nanometer array electrode and a preparation method and application thereof

Abstract

The application belongs to the technical field of electro-catalytic oxidation, and particularly relates to a metal-oxo salt modified transition metal hydroxide nano-array electrode and a preparation method and application thereof. The nano-array electrode is prepared by a solvothermal reaction of a current collector as a carrier, a transition metal salt, a metal-oxo salt and a precipitator in one step. In the obtained nano-array electrode material, on the one hand, the modified metal-oxo salt can control the electronic structure of the catalytic active center of the electrode, improve the intrinsic catalytic activity of the electrode, and on the other hand, the electrostatic repulsion between the metal-oxo salt and S 2‑ can effectively slow down the sulfur poisoning of the catalyst and improve the poison resistance of the electrode. In addition, the electrode material developed by the application has the advantages of simple, fast, economical and easy-to-scale production process, and has wide application value in the field of electrochemical treatment of sulfur-containing wastewater.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic oxidation technology. More specifically, it relates to a metal oxoate-modified transition metal hydroxide nanoarray electrode, its preparation method, and its application. Background Technology

[0002] Sulfides are among the most common pollutants in water resources. Sulfur-containing wastewater can poison aquatic organisms, and the hydrogen sulfide (H2S) gas formed by microbial sulfate reduction can corrode pipes and chemical reactors when released into the atmosphere. Traditional treatment methods for sulfur-containing wastewater, such as biochemical treatment, direct oxidation, and precipitation (Xu Zhiwei, Wang Xiaomei, Wang Jian, et al. Resource-based treatment of high-concentration sulfur-containing wastewater [J]. Sulfuric Acid Industry, 2022(05):39-43+47.), all require large amounts of chemicals and high energy input, posing safety and significant operating cost issues. Therefore, there is an urgent need to explore a more cost-effective and sustainable method for treating sulfur-containing wastewater.

[0003] Electrocatalytic oxidation technology is a promising method for treating sulfur-containing wastewater due to its clean, efficient, and sustainable characteristics. The catalyst is crucial for the electrocatalytic oxidation treatment of sulfur-containing wastewater. Transition metal hydroxides have been extensively studied due to their economical and simple preparation process and abundant active sites, making them a class of promising catalytic materials for the electrocatalytic oxidation of sulfur-containing wastewater.

[0004] However, such catalysts still suffer from low activity and poor stability, hindering their practical application in the electrocatalytic treatment of sulfur-containing wastewater. For example, Chinese patent application CN106807349A discloses a nano-metal element-modified transition metal hydroxide array catalyst prepared by electrodeposition. The modified catalyst exhibits excellent electrocatalytic hydrogen evolution performance and full water electrolysis performance. However, the electrocatalytic hydrogen evolution performance of this catalyst is achieved using alkaline solutions such as potassium hydroxide solution or neutral media such as phosphate buffer solution. Its effectiveness in treating sulfur-containing wastewater remains unknown. Furthermore, sulfur-containing wastewater differs significantly from the aforementioned media solutions, with a more complex composition. During complex interfacial reactions, the catalyst surface is susceptible to sulfur-containing wastewater saturation. 2- The corrosive and toxic effects of the catalyst cause changes in its structure, ultimately leading to the deactivation of most of the catalyst.

[0005] Therefore, it is of great significance to develop highly active and stable transition metal hydroxides for the electrocatalytic oxidation of sulfur-containing wastewater. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of existing transition metal hydroxides in electrocatalytic sulfide oxidation (SOR) reactions, namely low catalytic activity and poor stability, and to provide a method for preparing a metal oxoacid modified transition metal hydroxide catalyst.

[0007] The purpose of this invention is to provide a metal oxoate-modified transition metal hydroxide catalyst prepared by the aforementioned method.

[0008] Another object of the present invention is to provide the application of the metal oxoate-modified transition metal hydroxide catalyst.

[0009] The above-mentioned objective of this invention is achieved through the following technical solution:

[0010] This invention protects a method for preparing a metal oxoacid-modified transition metal hydroxide catalyst (nanoarray electrode), comprising the following steps:

[0011] Transition metal salts, metal oxoates, and precipitants are added to a solvent and fully dissolved to form a homogeneous mixed solution. A solvothermal reaction is then carried out until the reaction is complete, followed by post-processing to obtain the final product.

[0012] In their extensive preliminary experiments, the inventors discovered that in the aforementioned metal oxophosphate-modified transition metal hydroxide catalysts, the modified metal oxophosphate can modulate the electronic structure of the catalytic center on the catalyst, thereby enhancing the intrinsic catalytic activity of the catalyst; simultaneously, the metal oxophosphate reacts with S... 2- The electrostatic repulsion effectively mitigates sulfur poisoning in the catalyst and enhances its resistance to poisoning. Thanks to the modification with metal oxophosphates, the constructed catalyst material exhibits excellent catalytic activity and stability in the electrocatalytic oxidation of sulfides.

[0013] Furthermore, the temperature of the solvothermal reaction is 80–250°C.

[0014] Preferably, the current collector is added after a homogeneous mixed solution is formed. Adding the current collector followed by a solvothermal reaction yields a transition metal hydroxide catalyst modified with a metal oxoate and grown in situ within the current collector. This eliminates the need to transfer and immobilize the resulting catalyst onto a conductive support later, allowing the electrocatalytic performance of the catalyst to be fully realized.

[0015] More specifically, as a feasible preferred embodiment, the preparation method of the above-mentioned metal oxoate modified transition metal hydroxide catalyst includes the following steps: adding the transition metal salt, metal oxoate and precipitant into a solvent and dissolving them completely to form a homogeneous mixed solution; adding a current collector to the obtained homogeneous mixed solution; and carrying out a solvothermal reaction at 80-250°C until the reaction is complete; and then performing post-treatment to obtain the catalyst.

[0016] Preferably, the transition metal in the transition metal salt is selected from at least one of Co, Ni, Cu, Mn, Fe, Zn, Al, Sc, Ti, Y, Nb, Cd, Ce, Ga, In, and Ge. When one of these transition metals is selected as the main catalytically active transition metal, other transition metals from the above-mentioned group are selected as dopant metals. Adding a small amount can optimize the electronic structure of the catalytic active center of the resulting catalyst, thereby improving its catalytic activity. Generally, Co, Ni, Cu, Mn, and Fe are common catalytically active transition metals in sulfide oxidation reactions and are the main catalytically active metals, while Zn, Sc, Ti, Y, Nb, Tc, Cd, Ce, Ga, In, and Ge are dopant metals in the transition metal salt, i.e., conventional dopants. Appropriate doping is beneficial for further improving the activity of the resulting catalytic material.

[0017] More preferably, the transition metal in the transition metal salt is selected from at least one of Co, Ni, Cu, Mn, and Fe.

[0018] Preferably, the concentration of the transition metal salt is 0.001–5 mol / L, more preferably 0.05–3 mol / L, specifically 0.05 mol / L, 0.10 mol / L, 0.20 mol / L, 0.30 mol / L, 0.50 mol / L, 1.00 mol / L, 2.00 mol / L, or 3.00 mol / L;

[0019] Preferably, the metal in the metal oxometalate is selected from at least one of Sn, Mo, Cr, W, V, Nb, Ta, Ga, Ge, Sb, and Bi.

[0020] More preferably, the metal in the metal oxometalate is selected from at least one of Sn, Mo, Cr, W, and V.

[0021] Further, the mass concentration ratio of the metal oxoate to the transition metal salt is 1:(1-100), preferably 1:(1-50), specifically 1:1, 1:2, 1:4, 1:5, 1:10, 1:20 or 1:50.

[0022] Preferably, the temperature of the solvothermal reaction is 100–200°C, more preferably 120–180°C.

[0023] Preferably, the reaction takes 1 to 96 hours to complete, more preferably 2 to 30 hours.

[0024] Furthermore, the transition metal salt is one or more of nitrates, acetates, chlorides, carbonates, and sulfates.

[0025] Preferably, the precipitant is one or more of hexamethylenetetramine, sodium hydroxide, potassium hydroxide, urea, ammonia, sodium carbonate, and sodium bicarbonate.

[0026] Preferably, the solvent is one or more of the following: water, methanol, ethanol, propanol, butanol, isopropanol, ethylene glycol, propylene glycol, 1,4-butanediol, 1,2,4-butanetriol, 1,6-hexanediol, pentanediol, glycerol, benzyl alcohol, cyclohexanol, acetone, diethylene glycol, triethylene glycol, acetonitrile, methyl acetate, and ethyl acetate.

[0027] Preferably, the current collector is carbon cloth, carbon paper, or a metal current collector.

[0028] More preferably, the metal current collector is a metal foam, metal foil, metal plate, or metal mesh.

[0029] Furthermore, the metal current collector is selected from any one of Fe, Co, Ni, Zn, Al, Ti, and stainless steel.

[0030] Specifically, the post-processing includes cooling, washing, and drying.

[0031] The washing process involves washing the product with anhydrous ethanol 2 to 5 times.

[0032] The drying process can be carried out at 50-100℃ for 8-20 hours.

[0033] This invention protects the metal oxophosphate-modified transition metal hydroxide catalysts prepared by the aforementioned method.

[0034] This invention protects the application of the metal oxoate-modified transition metal hydroxide catalyst in electrocatalytic sulfide oxidation reactions.

[0035] This invention also protects the application of the metal oxoate-modified transition metal hydroxide catalyst in the treatment of sulfur-containing wastewater.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] This invention utilizes a current collector as a support to obtain a transition metal hydroxide catalyst modified with a metal oxoate via a simple solvothermal reaction. In the resulting catalyst, on the one hand, the modified metal oxoate can modulate the electronic structure of the catalytic center, improving intrinsic catalytic activity; on the other hand, the metal oxoate reacts with S... 2- The electrostatic repulsion effect can effectively mitigate sulfur poisoning of the catalyst and improve catalytic stability. In addition, the catalyst material developed in this invention has a simple, rapid, economical, and easily scaled-up production process, and can be widely applied to electrocatalytic treatment of sulfur-containing wastewater. Attached Figure Description

[0038] Figure 1This is a SEM image of the stannate-modified cobalt hydroxide nanoarray electrode prepared in Example 1.

[0039] Figure 2 This is a SEM image of the nickel hydroxide nanoarray electrode modified with stannate and molybdate as prepared in Example 2.

[0040] Figure 3 This is a SEM image of the cobalt hydroxide nanoarray electrode modified with vanadate, chromate and tungstate as prepared in Example 3.

[0041] Figure 4 This is a SEM image of the molybdate-modified cobalt manganese hydroxide nanoarray electrode prepared in Example 4.

[0042] Figure 5 This is a SEM image of the copper hydroxide iron nanoarray electrode modified with molybdate and tungstate as prepared in Example 5.

[0043] Figure 6 This is a SEM image of the nickel-iron hydroxide nanoarray electrode modified with tungstate, chromate and stannate as prepared in Example 6.

[0044] Figure 7 This is a SEM image of the molybdate-modified nickel-manganese-iron hydroxide nanoarray electrode prepared in Example 7.

[0045] Figure 8 This is a SEM image of the nickel-copper-iron nanoarray electrode modified with molybdate and vanadate prepared in Example 8.

[0046] Figure 9 The LSV (Linear sweep voltammetry) plots of SOR for Example 1 and Comparative Example 1 nanoarray electrodes at room temperature are shown.

[0047] Figure 10 The graph shows the stability test data of SOR using the chronopotentiometric method at room temperature for Example 1 and Comparative Example 1 nanoarray electrodes.

[0048] Figure 11 The LSV plots of SOR for Example 3 and Comparative Example 2 nanometer array electrodes at room temperature are shown.

[0049] Figure 12 The chart shows the statistical data of SOR stability tests performed at room temperature using the chronopotentiometric method on Example 3 and Comparative Example 2 nanometer array electrodes.

[0050] Figure 13 The LSV plots of SOR for Example 4 and Comparative Example 4 are obtained by performing SOR on a 3-nanometer array electrode at room temperature.

[0051] Figure 14 The chart shows the statistical data of SOR stability tests performed at room temperature using the chronopotentiometric method on Example 4 and Comparative Example 4 with a 3-nanometer array electrode.

[0052] Figure 15 LSV plots of SOR were obtained for Example 5 and Comparative Example 5 using a 4-nanometer array electrode at room temperature.

[0053] Figure 16 The graph shows the statistical data of SOR stability tests performed at room temperature using the chronopotentiometric method on Example 5 and Comparative Example 4 nanometer array electrodes.

[0054] Figure 17 LSV plots of SOR were obtained for Example 7 and Comparative Example 7 using a 5 nm array electrode at room temperature.

[0055] Figure 18 The chart shows the statistical data of SOR stability tests performed at room temperature using a chronopotentiometric method on 5-nanometer array electrodes in Example 7 and Comparative Example. Detailed Implementation

[0056] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0057] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0058] Example 1: Stannate-modified cobalt hydroxide nanoarray electrode (NF / CoOH-Sn)

[0059] The method for preparing the stannate-modified cobalt hydroxide nanoarray electrode includes the following steps:

[0060] S1. Dissolve 0.04 mmol Co(CH3COO)2·4H2O, 0.01 mmol Na2SnO3·6H2O and 1 mmol hexamethylenetetramine in 15 mL of ultrapure water to form a homogeneous mixed solution.

[0061] S2. Place two 1×3cm pieces of cleaned nickel foam (NF) into the mixture, stir for 30 min, then transfer it to a high-pressure reactor with a polytetrafluoroethylene liner and perform a hydrothermal reaction in a 180℃ drying oven for 8 h. After the reaction is complete, allow it to cool naturally. Wash the cooled material three times with anhydrous ethanol and dry it in a drying oven at 80℃ for 12 h to obtain a stannate-modified cobalt hydroxide nanoarray electrode (NF / CoOH-Sn) grown in situ on NF.

[0062] Material characterization:

[0063] The obtained product was characterized by SEM to obtain the material morphology. Figure 1 As can be seen from the figure, there is a uniformly distributed nanosheet structure on the NF current collector.

[0064] Example 2: Nickel hydroxide nanoarray electrode modified with stannate and molybdate (SS / NiOH-SnMo)

[0065] The method for preparing the stannate and molybdate-modified nickel hydroxide nanoarray electrode includes the following steps:

[0066] S1, take 0.2mmol Ni(NO3)2·6H2O, 0.05mmol Na2SnO3·6H2O, 0.05mmol(NH4)6Mo7O 24 • 4H2O and 1.2 mmol sodium hydroxide were dissolved in 15 mL of ethanol to form a homogeneous mixed solution;

[0067] S2. Place two cleaned 1×3cm stainless steel (SS) pieces into the mixture, stir for 30 min, then transfer to a high-pressure reactor with a polytetrafluoroethylene liner and perform a hydrothermal reaction in a 140℃ drying oven for 10 h. After the reaction is completed, allow it to cool naturally. The cooled material is washed three times with anhydrous ethanol and dried in a drying oven at 80℃ for 12 h to obtain a nickel hydroxide nanoarray electrode (SS / NiOH-SnMo) modified with stannate and molybdate grown in situ on SS.

[0068] Material characterization:

[0069] The obtained product was characterized by SEM to obtain the material morphology. Figure 2 As can be seen from the figure, there are uniformly distributed nanosheet structures on the SS current collector.

[0070] Example 3: Vanadate, chromate, and tungstate-modified cobalt hydroxide nanoarray electrode (CC / CoOH-VCrW)

[0071] The method for preparing the vanadate, chromate, and tungstate-modified cobalt hydroxide nanoarray electrode includes the following steps:

[0072] S1, Take 2.9 mmol CoCl2·6H2O, 0.03 mmol Na2CrO4, and 0.02 mmol (NH4). 10 H2(W2O7)6, 0.05 mmol NH4VO3 and 3 mmol potassium hydroxide were dissolved in a mixed solvent of 10 mL acetonitrile and 20 mL isopropanol to form a homogeneous mixed solution;

[0073] S2. Place two cleaned 1×3cm carbon cloth (CC) pieces into it, stir for 30 min, then transfer to a high-pressure reactor with a polytetrafluoroethylene liner and carry out hydrothermal reaction in a 120℃ forced-air drying oven for 8 h. After the reaction is completed, allow it to cool naturally. The cooled material is washed three times with anhydrous ethanol and dried in a forced-air drying oven at 60℃ for 12 h to obtain a cobalt hydroxide nanoarray electrode (CC / CoOH-VCrW) modified with vanadate, chromate and tungstate grown in situ on CC.

[0074] Material characterization:

[0075] The obtained product was characterized by SEM to obtain the material morphology. Figure 3 As can be seen from the figure, there is a uniformly distributed nanosheet array structure on the CC current collector.

[0076] Example 4: Molybdate-modified cobalt-manganese hydroxide nanoarray electrode (IF / CoMnOH-Mo)

[0077] The preparation method of the molybdate-modified cobalt manganese hydroxide nanoarray electrode includes the following steps:

[0078] S1, take 0.4mmol Co(NO3)2·6H2O, 0.05mmol MnCl2.4H2O, 0.05mmol(NH4)6Mo7O 24 • 4H2O and 1 mmol of urea are dissolved in 15 mL of ethyl acetate to form a homogeneous mixed solution;

[0079] S2. Place two 1×3cm pieces of foamed iron (IF) that have been washed clean into the reactor and stir for 30 minutes. Then, transfer the mixture to a high-pressure reactor with a polytetrafluoroethylene liner and perform a hydrothermal reaction in a 120°C oven for 8 hours. After the reaction is completed, allow the material to cool naturally. Wash the cooled material three times with anhydrous ethanol and dry it in a 60°C oven for 12 hours to obtain a molybdate-modified cobalt manganese hydroxide nanoarray electrode (IF / CoMnOH-Mo) grown in situ on the IF.

[0080] Material characterization:

[0081] The obtained product was characterized by SEM to obtain the material morphology. Figure 4 As can be seen from the figure, there is a uniformly distributed array of nanorods on the IF current collector.

[0082] Example 5: Molybdate and tungstate-modified copper hydroxide iron nanoarray electrode (TP / CuFeOH-MoW)

[0083] The preparation method of the molybdate and tungstate modified copper hydroxide iron nanoarray electrode includes the following steps:

[0084] S1, take 1.0mmol CuSO4·5H2O, 0.5mmol Fe(NO3)3·9H2O, 0.25mmol(NH4)6Mo7O 24 • 4H₂O, 0.25 mmol (NH₄) 10 H2(W2O7)6 and 2 mmol of sodium carbonate were dissolved in 10 mL of ethylene glycol and 20 mL of glycerol and a mixed solvent to form a homogeneous mixed solution;

[0085] S2. Place two 1×3cm titanium plates (TP) that have been washed clean into the reactor and stir for 30 minutes. Then, transfer the mixture to a high-pressure reactor with a polytetrafluoroethylene liner and perform a hydrothermal reaction in a 120°C oven for 12 hours. After the reaction is completed, allow the mixture to cool naturally. Wash the cooled material three times with anhydrous ethanol and dry it in a 60°C oven for 12 hours to obtain a copper hydroxide iron nanoarray electrode (TP / CuFeOH-MoW) modified with molybdate and tungstate grown in situ on TP.

[0086] Material characterization:

[0087] The obtained product was characterized by SEM to obtain the material morphology. Figure 5 As can be seen from the figure, there is a uniformly distributed nanosheet array structure on the TP current collector.

[0088] Example 6: Nickel-iron hydroxide nanoarray electrode modified with tungstate, chromate, and stannate (NF / NiFeOH-WCrSn)

[0089] The preparation method of the nickel-iron hydroxide nanoarray electrode modified with tungstate, chromate and stannate includes the following steps:

[0090] S1, take 0.6mmol NiCl2.6H2O, 0.1mmol Fe(NO3)3·9H2O, 0.1mmol(NH4) 10 H2(W2O7)6, 0.1 mmol Na2CrO4, 0.1 mmol Na2SnO3·6H2O and 4 mmol sodium bicarbonate were dissolved in 15 mL of acetone to form a homogeneous mixed solution.

[0091] S2. Place two 1×3cm pieces of NF that have been washed clean into the reactor and stir for 30 minutes. Then, transfer the mixture to a high-pressure reactor with a polytetrafluoroethylene liner and perform a hydrothermal reaction in a 120°C oven for 12 hours. After the reaction is completed, allow the material to cool naturally. Wash the cooled material three times with anhydrous ethanol and dry it in a 60°C oven for 12 hours to obtain a nickel-iron hydroxide nanoarray electrode (NF / NiFeOH-WCrSn) modified with tungstate, chromate and stannate grown in situ on NF.

[0092] Material characterization:

[0093] The obtained product was characterized by SEM to obtain the material morphology. Figure 6 As can be seen from the figure, there is a uniformly distributed nanosheet array structure on the NF current collector.

[0094] Example 7: Molybdate-modified nickel-manganese-iron hydroxide nanoarray electrode (CC / NiMnFeOH-Mo)

[0095] The preparation method of the molybdate-modified nickel-manganese-iron hydroxide nanoarray electrode includes the following steps:

[0096] S1, take 0.05mmol Ni(NO3)2·6H2O, 0.03mmol Mn(NO3)2, 0.01mmol FeCl3·6H2O, 0.01mmol (NH4)6Mo7O 24 • 4H2O and 1 mmol of hexamethylenetetramine were dissolved in 15 mL of methanol to form a homogeneous mixed solution;

[0097] S2. Place two cleaned 1×3cm carbon cloth (CC) pieces into it, stir for 30 min, then transfer to a high-pressure reactor with a polytetrafluoroethylene liner and carry out hydrothermal reaction in a 120℃ forced-air drying oven for 8 h. After the reaction is completed, allow it to cool naturally. The cooled material is washed three times with anhydrous ethanol and dried in a forced-air drying oven at 60℃ for 12 h to obtain a molybdate-modified nickel manganese iron hydroxide nanoarray electrode (CC / NiMnFeOH-Mo) grown in situ on NF.

[0098] Material characterization:

[0099] The obtained product was characterized by SEM to obtain the material morphology. Figure 7 As can be seen from the figure, there is a uniformly distributed nanosheet array structure on the CC current collector.

[0100] Example 8: Molybdate and vanadate modified nickel-copper-iron hydroxide nanoarray electrode (TM / NiCuFeOH-MoV)

[0101] The preparation method of the molybdate and vanadate-modified nickel-copper-iron hydroxide nanoarray electrode includes the following steps:

[0102] S1, take 0.2mmol Ni(CH3COO)2·4H2O, 0.2mmol Cu(NO3)2·3H2O, 0.05mmol FeCl3·6H2O, 0.025mmol (NH4)6Mo7O 24 • 4H2O, 0.025 mmol NH4VO3 and 1 mmol hexamethylenetetramine were dissolved in a mixed solvent of 10 mL ultrapure water and 5 mL ethanol to form a homogeneous mixed solution;

[0103] S2. Place two cleaned 1×3cm titanium mesh (TM) pieces into it, stir for 30 min, then transfer to a high-pressure reactor with a polytetrafluoroethylene liner and carry out hydrothermal reaction in a 120℃ drying oven for 8 h. After the reaction is completed, allow it to cool naturally. The cooled material is washed three times with anhydrous ethanol and dried in a 60℃ drying oven for 12 h to obtain a molybdate and vanadate modified nickel-copper-iron hydroxide nanoarray electrode (TM / NiCuFeOH-MoV) grown in situ on TM.

[0104] Material characterization:

[0105] The obtained product was characterized by SEM to obtain the material morphology. Figure 8 As can be seen from the figure, there is a uniformly distributed nanosheet array structure on the TM current collector.

[0106] Comparative Example 1: Cobalt hydroxide nanoarray electrode (NF / CoOH)

[0107] Compared with Example 1, Comparative Example 1 differs in that it was not modified with stannate.

[0108] Specifically, the preparation method of the cobalt hydroxide nanoarray electrode includes the following steps:

[0109] S1. Dissolve 0.05 mmol Co(CH3COO)2·4H2O and 1 mmol hexamethylenetetramine in 15 mL of ultrapure water to form a homogeneous mixed solution;

[0110] S2. Place two 1×3cm NF pieces that have been washed clean into the reactor and stir for 30 minutes. Then, transfer the mixture to a high-pressure reactor with a polytetrafluoroethylene liner and perform a hydrothermal reaction in a 180°C oven for 8 hours. After the reaction is completed, allow the mixture to cool naturally. Wash the cooled material three times with anhydrous ethanol and dry it in an 80°C oven for 12 hours to obtain a cobalt hydroxide nanoarray electrode (NF / CoOH) grown in situ on NF.

[0111] Comparative Example 2: Cobalt-iron hydroxide nanoarray electrode (CC / CoOH)

[0112] Compared with Example 3, Comparative Example 2 differs in that it was not modified with vanadate, chromate and tungstate.

[0113] Specifically, the preparation method of the cobalt hydroxide nanoarray electrode includes the following steps:

[0114] S1. Dissolve 3.0 mmol CoCl2·6H2O and 3 mmol potassium hydroxide in a mixed solvent of 10 mL acetonitrile and 20 mL isopropanol to form a homogeneous mixed solution;

[0115] S2. Place two 1×3cm carbon cloth (CC) pieces that have been washed clean into the container, stir for 30 minutes, and then transfer them to a high-pressure reactor with a polytetrafluoroethylene liner. Perform a hydrothermal reaction in a 120℃ drying oven for 8 hours. After the reaction is completed, allow it to cool naturally. Wash the cooled material three times with anhydrous ethanol and dry it in a 60℃ drying oven for 12 hours to obtain a cobalt hydroxide nanoarray electrode (CC / CoOH) grown in situ on CC.

[0116] Comparative Example 3: Cobalt-manganese hydroxide nanoarray electrode (IF / CoMnOH)

[0117] Compared with Example 4, Comparative Example 3 differs in that it was not modified with molybdate.

[0118] Specifically, the preparation method of the cobalt manganese hydroxide nanoarray electrode includes the following steps:

[0119] S1. Dissolve 0.45 mmol Co(NO3)2·6H2O, 0.05 mmol MnCl2·4H2O and 1 mmol urea in 15 mL of ethyl acetate to form a homogeneous mixed solution;

[0120] S2. Place two 1×3cm pieces of foamed iron (IF) that have been washed clean into the reactor and stir for 30 minutes. Then, transfer the mixture to a high-pressure reactor with a polytetrafluoroethylene liner and perform a hydrothermal reaction in a 120°C oven for 8 hours. After the reaction is complete, allow the material to cool naturally. Wash the cooled material three times with anhydrous ethanol and dry it in a 60°C oven for 12 hours to obtain a cobalt manganese hydroxide nanoarray electrode (IF / CoMnOH) grown in situ on the IF.

[0121] Comparative Example 4: Copper hydroxide iron nanoarray electrode (TP / CuFeOH)

[0122] Compared with Example 5, Comparative Example 4 differs in that it was not modified with molybdate and tungstate.

[0123] Specifically, the preparation method of the copper hydroxide iron nanoarray electrode includes the following steps:

[0124] S1. Dissolve 1.0 mmol CuSO4·5H2O, 0.1 mmol Fe(NO3)3·9H2O and 2 mmol sodium carbonate in 10 mL ethylene glycol and 20 mL glycerol and mixed solvent to form a homogeneous mixed solution;

[0125] S2. Place two 1×3cm titanium plates (TP) that have been washed clean into the reactor. Stir for 30 minutes, then transfer the mixture to a high-pressure reactor with a polytetrafluoroethylene liner. Perform a hydrothermal reaction in a 120°C oven for 12 hours. After the reaction is complete, allow the material to cool naturally. Wash the cooled material three times with anhydrous ethanol and dry it in a 60°C oven for 12 hours to obtain a copper hydroxide iron nanoarray electrode (TP / CuFeOH) grown in situ on TP.

[0126] Comparative Example 5: Nickel-manganese-iron hydroxide nanoarray electrode (CC / NiMnFeOH)

[0127] Compared with Example 7, Comparative Example 5 differs in that it was not modified with molybdate.

[0128] Specifically, the preparation method of the nickel-manganese-iron hydroxide nanoarray electrode includes the following steps:

[0129] S1. Dissolve 0.06 mmol Ni(NO3)2·6H2O, 0.03 mmol Mn(NO3)2, 0.01 mmol FeCl3·6H2O and 1 mmol hexamethylenetetramine in 15 mL of methanol to form a homogeneous mixed solution.

[0130] S2. Place two 1×3cm carbon cloth (CC) pieces that have been washed clean into the container, stir for 30 minutes, and then transfer them to a high-pressure reactor with a polytetrafluoroethylene liner. Perform a hydrothermal reaction in a 120℃ drying oven for 8 hours. After the reaction is completed, allow it to cool naturally. Wash the cooled material three times with anhydrous ethanol and dry it in a 60℃ drying oven for 12 hours to obtain a nickel-manganese-iron hydroxide nanoarray electrode (CC / NiMnFeOH) grown in situ on CC.

[0131] Performance test object

[0132] The following examples, namely Examples 1, 3, 4, 5, 7 and Comparative Examples 1 to 5, are used to measure the activity and stability of the prepared nanoelectrode materials in the electrocatalytic oxidation of sulfides at room temperature. The results of other examples are similar to those of Examples 1, 3, 4, 5, and 7.

[0133] Application Example 1: Performance Testing of Electrocatalytic Sulfide Oxidation (SOR)

[0134] Electrochemical measurements were performed using a computer-controlled electrochemical workstation (Autolab, PGSTAT302N) with a standard three-electrode system. The performance index for evaluating the activity of the electrocatalytic material was a current density reaching 100 mA cm⁻¹. -2 Required voltage (E) 100) The lower the voltage value (or the faster the current density rises), the better the electrocatalytic activity; Method for evaluating the stability of electrocatalytic materials: The change of voltage with time under a constant current (0.10 A), that is, chronopotentiometry (CP). The smaller the amplitude of the voltage change with time, the better the electrocatalytic stability.

[0135] The electrocatalytic activity and stability of the samples were studied in a three-electrode system with the array electrode (cut into 1×1 cm 2 ) prepared in the examples or comparative examples as the working electrode, a carbon rod as the counter electrode, and a Hg / HgO (immersed in 1.0 M KOH solution) electrode as the reference electrode. The electrocatalytic activity test was carried out by scanning the catalyst for activation through CV (-0.90~0 V vs. Hg / HgO) in a sulfide electrolyte (1 M NaOH + 1 M Na2S, pH = 13.74) under stirring. After the CV scan results were stable, the LSV curve (-0.90~0 V vs. Hg / HgO) was tested, and 95% iR compensation was performed on the LSV curve. The electrocatalytic stability test was carried out by scanning the catalyst for activation through CV (-0.90~0 V vs. Hg / HgO) in a sulfide electrolyte (1 M NaOH + 1 M Na2S, pH = 13.74) under stirring. After the CV scan results were stable, chronopotentiometry stability test was carried out at a current density of 100 mA cm -2 . During the test process, it was ensured that the electrolyte solution contained sufficient sulfide, and the solution was changed every 36 h. According to the formula E(RHE) = E(Hg / HgO) + 0.0977 + 0.05916×pH, the potential value E(RHE) was converted from E(Hg / HgO).

[0136] The SOR activity and stability tests were carried out on the tinate-modified cobalt hydroxide nanorod array electrode (NF / CoOH-Sn) of Example 1 and the cobalt hydroxide nanorod array electrode (NF / CoOH) of Comparative Example 1. The results are shown in Figure 9 and Figure 10 ;

[0137] It can be seen from Figure 9 that for the activity of SOR, compared with NF / CoOH, NF / CoOH-Sn has a smaller E 100 , E 100 vs. RHE are NF / CoOH-Sn (0.402 V) < NF / CoOH (0.625 V) respectively. It can be seen from Figure 10 that for the stability of SOR, NF / CoOH-Sn at 100 mA cm -2It can operate stably for at least 108 h (only measured up to 108 h) under a current density of [specific value], while the performance of NF / CoOH significantly decreases after 36 h of operation. As time increases, the voltage values of both NF / CoOH-Sn and NF / CoOH increase, but the voltage value of NF / CoOH increases faster. After replacing the sulfide-containing electrolyte solution, the voltage value of NF / CoOH-Sn can recover to the previous level, while that of NF / CoOH cannot, indicating the excellent stability of NF / CoOH-Sn. Therefore, compared with the cobalt hydroxide nanorod array electrode, the stannate-modified cobalt hydroxide nanorod array electrode has more excellent activity and stability in SOR.

[0138] Performance test of electrocatalytic sulfide oxidation reaction (SOR) in Application Example 2

[0139] The SOR activity and stability tests were carried out on the cobalt hydroxide nanorod array electrode modified with vanadate, chromate and tungstate (CC / CoOH-VCrW) in Example 3 and the cobalt hydroxide nanorod array electrode (CC / CoOH) in Comparative Example 2. The test method was the same as that in Application Example 1, and the results are shown in Figure 11 and Figure 12 ;

[0140] It can be seen from Figure 11 that for the activity of SOR, compared with CC / CoOH, CC / CoOH-VCrW has a smaller E 100 and E 100 vs. RHE are CC / CoOH-VCrW (0.423 V) < CC / CoOH (0.548 V) respectively. It can be seen from Figure 12 that for the stability of SOR, CC / CoOH-VCrW can operate stably for at least 108 h under a current density of 100 mA cm -2 while the performance of CC / CoOH significantly decreases after 36 h of operation. As time increases, the voltage values of both CC / CoOH-VCrW and CC / CoOH increase, but the voltage value of CC / CoOH increases faster. After replacing the sulfide-containing electrolyte solution, the voltage value of CC / CoOH-VCrW can recover to the previous level, while that of NF / CoOH cannot, indicating the excellent stability of CC / CoOH-VCrW. Therefore, compared with the cobalt hydroxide nanorod array electrode, the cobalt hydroxide nanorod array electrode modified with vanadate, chromate and tungstate has more excellent activity and stability in SOR.

[0141] Performance test of electrocatalytic sulfide oxidation reaction (SOR) in Application Example 3

[0142] The SOR activity and stability tests were carried out on the molybdate-modified cobalt manganese hydroxide nanorod array electrode (IF / CoMnOH-Mo) of Example 4 and the cobalt manganese hydroxide nanorod array electrode (IF / CoMnOH) of Comparative Example 3. The test method was the same as that of Application Example 1, and the results are shown in Figure 13 and Figure 14 ;

[0143] It can be seen from Figure 13 that for the activity of SOR, compared with IF / CoMnOH, IF / CoMnOH-Mo has a smaller E 100 and E 100 vs. RHE are IF / CoMnOH-Mo (0.413 V) < IF / CoMnOH (0.762 V) respectively. It can be seen from Figure 14 that for the stability of SOR, IF / CoMnOH-Mo can stably operate for at least 108 h at a current density of 100 mA cm -2 , while the performance of IF / CoMnOH decreases significantly after operating for 36 h. As time increases, the voltage values of both IF / CoMnOH-Mo and IF / CoMnOH increase, but the voltage value of IF / CoMnOH increases faster. After replacing the sulfide-containing electrolyte solution, the voltage value of IF / CoMnOH-Mo can recover to the previous level, while the voltage value of IF / CoMnOH cannot. It can be seen that IF / CoMnOH-Mo has excellent stability. Therefore, compared with the cobalt manganese hydroxide nanorod array electrode, the molybdate-modified cobalt manganese hydroxide nanorod array electrode has more excellent activity and stability in SOR.

[0144] Performance test of electrocatalytic sulfide oxidation reaction (SOR) in Application Example 4

[0145] The SOR activity and stability tests were carried out on the molybdate- and tungstate-modified copper iron hydroxide nanorod array electrode (TP / CuFeOH-MoW) of Example 5 and the copper iron hydroxide nanorod array electrode (TP / CuFeOH) of Comparative Example 4. The test method was the same as that of Application Example 1, and the results are shown in Figure 15 and Figure 16 ;

[0146] It can be seen from Figure 15 that for the activity of SOR, compared with TP / CuFeOH, TP / CuFeOH-MoW has a smaller E 100 and E 100 vs. RHE are TP / CuFeOH-MoW (0.481 V) < TP / CuFeOH (0.683 V) respectively. It can be seen from Figure 16 that for the stability of SOR, TP / CuFeOH-MoW can stably operate at 100 mA cm -2It can operate stably for at least 108 h under a current density of [value], while the performance of TP / CuFeOH significantly decreases after 36 h of operation. As time increases, the voltage values of both TP / CuFeOH-MoW and TP / CuFeOH increase, but the voltage value of TP / CuFeOH increases faster. After replacing the sulfide-containing electrolyte solution, the voltage value of TP / CuFeOH-MoW can recover to the previous level, while that of TP / CuFeOH cannot, indicating the excellent stability of TP / CuFeOH-MoW. Therefore, compared with the copper iron hydroxide nanorarray electrode, the copper iron hydroxide nanorarray electrode modified with molybdate and tungstate has more excellent activity and stability in SOR.

[0147] Performance test of electrocatalytic sulfide oxidation reaction (SOR) in Application Example 5

[0148] The SOR activity and stability tests were carried out on the molybdate-modified nickel manganese iron hydroxide nanorarray electrode (CC / NiMnFeOH-Mo) in Example 7 and the nickel manganese iron hydroxide nanorarray electrode (CC / NiMnFeOH) in Comparative Example 5. The test method was the same as that in Application Example 1, and the results are shown in Figure 17 and Figure 18 ;

[0149] From Figure 17 It can be seen that for the activity of SOR, compared with CC / NiMnFeOH, CC / NiMnFeOH-Mo has a smaller E 100 E 100 vs. RHE are CC / NiMnFeOH-Mo (0.319 V) < CC / NiMnFeOH (0.431 V) respectively. From Figure 18 It can be seen that for the stability of SOR, CC / NiMnFeOH-Mo can operate stably for at least 108 h under a current density of 100 mA cm -2 while the performance of CC / NiMnFeOH significantly decreases after 36 h of operation. As time increases, the voltage values of both CC / NiMnFeOH-Mo and CC / NiMnFeOH increase, but the voltage value of CC / NiMnFeOH increases faster. After replacing the sulfide-containing electrolyte solution, the voltage value of CC / NiMnFeOH-Mo can recover to the previous level, while that of CC / NiMnFeOH cannot, indicating the excellent stability of CC / NiMnFeOH-Mo. Therefore, compared with the nickel manganese iron hydroxide nanorarray electrode, the molybdate-modified nickel manganese iron hydroxide nanorarray electrode has more excellent activity and stability in SOR.

[0150] In summary, the nanoarray electrodes obtained in the examples exhibit superior electrocatalytic SOR activity and stability compared to the corresponding nanoarray electrodes. Therefore, the metal oxoate-modified transition metal hydroxide nanoarray electrodes prepared in this invention have significant application value in SOR and can be widely applied to the electrocatalysis of sulfur-containing wastewater.

[0151] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. The application of metal oxophosphate-modified transition metal hydroxide catalysts in the treatment of sulfur-containing wastewater, characterized in that, The preparation method of the metal oxoate-modified transition metal hydroxide catalyst includes the following steps: The transition metal salt, metal oxometalate, and precipitant are added to a solvent and fully dissolved to form a homogeneous mixed solution. Then, a solvothermal reaction is carried out until the reaction is complete. After post-processing, the product is obtained. The mass concentration ratio of the metal oxophosphate to the transition metal salt is 1:(1-100); After a homogeneous mixed solution is formed, add the current collector; The transition metal in the transition metal salt is selected from at least one of Co, Ni, Cu, Mn, and Fe; The metal in the metal oxometalate is selected from at least one of Sn, Mo, Cr, W, and V.

2. The application according to claim 1, characterized in that, The temperature of the solvothermal reaction is 80~250 ℃.

3. The application according to claim 1, characterized in that, The precipitant is one or more of hexamethylenetetramine, sodium hydroxide, potassium hydroxide, urea, ammonia, sodium carbonate, and sodium bicarbonate.

4. The application according to claim 1, characterized in that, The solvent is one or more of the following: water, methanol, ethanol, propanol, butanol, isopropanol, ethylene glycol, propylene glycol, 1,4-butanediol, 1,2,4-butanetriol, 1,6-hexanediol, pentanediol, glycerol, benzyl alcohol, cyclohexanol, acetone, diethylene glycol, triethylene glycol, acetonitrile, methyl acetate, and ethyl acetate.

5. The application according to claim 1, characterized in that, The current collector is made of carbon cloth, carbon paper, or metal.

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