A method for preparing a cathode electrode for electrocatalytic reduction of chlorate and applications thereof
By using a cathode electrode with a Pd/C catalyst loaded on molybdenum foil, the problems of high energy consumption, numerous byproducts, and poor safety in the chlorate reduction process were solved, achieving efficient and economical selective reduction of chlorate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TAIYUAN UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2025-02-28
- Publication Date
- 2026-05-29
AI Technical Summary
Existing technologies for chlorate reduction suffer from high energy consumption, byproduct generation, high cost, and poor safety, especially when using precious metal catalysts and hydrogen environments.
Using molybdenum foil as the substrate material and supporting a Pd/C catalyst, a non-noble metal cathode electrode was prepared by utilizing the hydrogenation activation effect of Pd and the redox properties of polyvalent Mo species for the electrocatalytic reduction of chlorate.
It reduces costs, improves safety, reduces hydrogen evolution side reactions, and achieves selective reduction and efficient and stable catalysis of chlorate.
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Figure CN120024969B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of chlorate treatment technology, specifically relating to a method for preparing a cathode electrode for electrocatalytic reduction of chlorate and its application. Background Technology
[0002] Chlorate, a byproduct of industrial processes such as chlor-alkali production and electrochemical disinfectant preparation, is extremely persistent in aquatic environments and difficult to degrade naturally. Traditional chlorate reduction methods include chemical reduction, biological reduction, and electrochemical reduction.
[0003] Chemical reduction method: using reducing agents such as sulfites (SO3) 2- ), sulfides (S 2- ) or iron (Fe 2+ The reduction of chlorate to chloride ions is often achieved by adding an excessive amount of reducing agent, which produces reduction byproducts such as sulfates and sulfides. Furthermore, some reducing agents are toxic or corrosive, and improper handling may cause harm to the environment.
[0004] Bioreduction: This method utilizes specific microorganisms to reduce chlorate to chloride ions under anaerobic conditions. However, the bioreduction method has disadvantages such as long reaction time and large reactor footprint because the metabolism and reproduction of microorganisms require time. Furthermore, the microorganisms are sensitive to environmental conditions, requiring strict control of reaction conditions.
[0005] Electrochemical reduction method: By applying an external voltage, chlorate is reduced to chloride ions at the electrode surface. This method offers controllable conditions, but the presence of hydrogen evolution side reactions leads to increased energy consumption.
[0006] In recent years, the catalytic reduction of chlorate has attracted much attention. A Plá-Hernández, F Rey, AEPalomares. Pt-zeolites as active catalysts for the removal of chlorate in water by hydrogenation reactions[J]. Catalysis Today, 2024, 429: 114461, utilizes the synergistic effect of numerous acidic sites in zeolites and platinum to achieve the simultaneous reduction of chlorate and bromate; Sikora E, Karacs G, Kocserha BVL, et al. Hydrogenation of chlorate ions by commercialcarbon supported palladium catalysts-a comparative study[J]. Reactionkinetics, mechanisms and catalysis, 2020, 131(1):129-137, points out that under acidic conditions, combining Pd, Ru, and Rh with activated carbon supports can serve as potential catalysts for the reduction of chlorate and perchlorate; Gao J, Xie S, Liu F. Preparation and Synergy of Supported Ru~O and Pd~O for Rapid Chlorate Reduction at pH 7 [J]. Environmental Science & Technology: ES&T, 2023, using a Ru-Pd / C catalyst to reduce 100 mM chlorate under 1 atm hydrogen and 20 °C. However, chlorate reduction based on hydrogenation usually requires a noble metal as the active site and the reaction must occur in a hydrogen environment.
[0007] Electrocatalytic reduction is a feasible alternative. Wei H, Yancai Y, Lizhi Z. Advances in Electrochemical Reductive Removal of Oxyanions in Water[J]. Acta Chimica Sinica, 2023, 81(8): 979 points out that in acidic media, under the influence of applied current, metal ions have high hydrogen evolution activity at the cathode, which helps to reduce oxygen-containing compounds at the cathode. Bibo Xu, Yunbo Zhai, Wei Chen, et al. Perchlorate catalysis reduction by benzalkonium chloride immobilized biomasscarbon supported Re-Pd bimetallic cluster particle electrode[J]. Chemical Engineering Journal, 2018. This study achieves the catalytic reduction of perchlorate by immobilizing Re-Pd bimetallic cluster particles on biomass carbon. Yao F, Zhong Y, Yang Q, et al. Effective adsorption / electrocatalytic degradation of perchlorate using Pd / Pt supported on N-doped activated carbon fiber cathode[J]. Journal of hazardous materials, 2016, 323(B). This study utilizes Pd / Pt supported on nitrogen-doped activated carbon fiber cathode to achieve effective adsorption / electrocatalytic degradation of perchlorate. However, in the indirect reduction of electrode surface contaminants by highly reducing H (H*) atoms generated from noble metal ions, energy consumption increases, and a large number of byproducts are produced, reducing electron utilization efficiency. Therefore, efficient utilization of H* and direct catalytic reduction on the electrode surface are key to improving reaction efficiency and reducing energy consumption. Summary of the Invention
[0008] To address the aforementioned problems, this invention provides a method for preparing a cathode electrode for the electrocatalytic reduction of chlorate and its application. Leveraging the superior redox capabilities of transition metals, the electrocatalytic reduction of chlorate is achieved using non-noble metals. This system utilizes molybdenum foil as the substrate material and supports Pd / C. Through the hydrogenation activation of Pd and the excellent redox properties of polyvalent Mo species, the electrocatalytic reduction of chlorate is effectively realized.
[0009] The present invention adopts the following technical solution:
[0010] A method for preparing a cathode electrode for the electrocatalytic reduction of chlorate includes the following steps:
[0011] S1. Cut the high-purity molybdenum foil into 50 mm × 25 mm × 0.2 mm sheets, place them in anhydrous ethanol and sonicate for 10 min, then place them in ultrapure water and sonicate for 10 min to remove surface organic matter and impurities.
[0012] S2. Prepare a 1 mol / L phosphoric acid solution in a 250 mL volumetric flask. Weigh 0.4625 g of ammonium fluoride and add it to the phosphoric acid solution. Stir until homogeneous. This solution will be used as the electrolyte in this experiment.
[0013] S3. Take 200 mL of electrolyte and pour it into the electrolytic cell. Use high-purity molybdenum foil as the working electrode and Pt sheet as the counter electrode. Make the distance between the two electrodes 1.5 cm and ensure that they are in full contact with the electrolyte at the same time. Apply a voltage of 0.3 V using a constant voltage power supply for 15 min.
[0014] S4. After the reaction is complete, the anode is removed, washed with ethanol, and then vacuum dried at 45°C for 12 hours to obtain MoO2 grown on molybdenum foil. X Oxide layer, denoted as MoO X / MF;
[0015] S5. Disperse 10 mg of 10% Pd / C in 950 μl of isopropanol, add 50 μl of Nafion solution, sonicate for 20 min to form black ink, and uniformly drop it onto MoO2. X Pd / C-MoO was obtained by vacuum drying at 45 °C for 12 h on / MF. X / MF electrode.
[0016] A cathode electrode is used for the electrocatalytic reduction of chlorate.
[0017] A method for using a cathode electrode for the electrocatalytic reduction of chlorate includes the following steps:
[0018] S1. In the split-cell electrochemical reactor, the reactor is divided into a cathode cell and an anode cell by a proton exchange membrane, wherein the cathode cell is 400 mL and the anode cell is 200 mL.
[0019] S2, The anode is an iridium-tantalum / titanium electrode, and the cathode is a Pd / C-MoO electrode. X / MF electrode, with an effective area of 10 cm² for both anode and cathode. 2 The geometric surface area is 10 cm². 2 The distance between the anode and cathode is 20mm;
[0020] S3. Add 170 mL of ultrapure water to the anode tank and 340 mL of 1 mM chlorate solution to the cathode tank. Then, add 1 M H2SO4 dropwise to adjust the pH of the solution to below 2. Stir with a magnetic stirrer until the solution is evenly distributed. The experiment is carried out under an external constant pressure of 3-6 V.
[0021] The beneficial effects of this invention are as follows:
[0022] First, the use of non-precious metals significantly reduces costs and improves the economics of the technology. Second, it avoids the dangerous operation of adding hydrogen gas during the hydrogenation of precious metals, thus significantly improving safety. Third, the new catalytic system reduces the occurrence of hydrogen evolution side reactions and achieves selective reduction of chlorate, ensuring the stability and efficiency of catalytic reduction. Attached Figure Description
[0023] Figure 1 This is a flowchart illustrating the preparation process of the cathode electrode of the present invention;
[0024] Figure 2 This is a schematic diagram of the apparatus for the electrocatalytic reduction of chlorate using the cathode electrode of the present invention;
[0025] Figure 3 The reduction rate curves of chlorate under different reduction voltages are shown.
[0026] Figure 4 The graph shows the reduction rate of chlorate under different pH conditions.
[0027] Figure 5 The graph shows the reduction rate of chlorate at different chlorate solution concentrations.
[0028] Figure 6 The reduction curve of chlorate is shown under the conditions of pH 2.0, reduction voltage 3 V, and reduction current 12 mA.
[0029] Figure 7 Pd / C-MoO X / MF pair Selective reduction curve;
[0030] Wherein: 1-molybdenum foil; 2-electrolytic cell; 3-magnetic stirrer; 4-electrochemical workstation; 5-pipette; 6-vacuum drying oven. Detailed Implementation
[0031] To make the objectives, technical solutions, and advantages of this invention clearer, specific embodiments of the invention are described in detail, but are not limited thereto. Unless otherwise specified, the raw materials used in the embodiments are all commercially available products; and unless otherwise specified, the methods used are methods commonly used in the art.
[0032] A method for preparing a cathode electrode for the electrocatalytic reduction of chlorate includes the following steps:
[0033] S1. Cut the high-purity molybdenum foil into 50 mm × 25 mm × 0.2 mm sheets, place them in anhydrous ethanol and sonicate for 10 min, then place them in ultrapure water and sonicate for 10 min to remove surface organic matter and impurities.
[0034] S2. Prepare a 1 mol / L phosphoric acid solution in a 250 mL volumetric flask. Weigh 0.4625 g of ammonium fluoride and add it to the phosphoric acid solution. Stir until homogeneous. This solution will be used as the electrolyte in this experiment.
[0035] S3. Take 200 mL of electrolyte and pour it into the electrolytic cell. Use high-purity molybdenum foil as the working electrode and Pt sheet as the counter electrode. Make the distance between the two electrodes 1.5 cm and ensure that they are in full contact with the electrolyte at the same time. Apply a voltage of 0.3 V using a constant voltage power supply for 15 min.
[0036] S4. After the reaction is complete, the anode is removed, washed with ethanol, and then vacuum dried at 45°C for 12 hours to obtain MoO2 grown on molybdenum foil. X Oxide layer, denoted as MoO X / MF;
[0037] S5. Disperse 10 mg of 10% Pd / C in 950 μl of isopropanol, add 50 μl of Nafion solution, sonicate for 20 min to form black ink, and uniformly drop it onto MoO2. X Pd / C-MoO was obtained by vacuum drying at 45 °C for 12 h on / MF. X / MF electrode.
[0038] Example 1
[0039] A method for electrocatalytic reduction of chlorate using a cathode electrode was conducted under different reduction voltage conditions. The reduction voltages were 2V, 3V, 4V, 5V, 6V and 8V, respectively. The reduction experiment was carried out for 36 hours in separate tanks with an initial molar concentration of chlorate of 1mM and an initial pH of 2. Figure 3 The relationship between different voltages and reduction rates was investigated, and the results showed that when Pd / C-MoO X When the reduction voltage of the / MF electrode was reduced from 8V to 3V, the chlorate reduction rate increased from 78.71% to 98.24%; when the voltage was further reduced to 2V, the reduction efficiency decreased to 87.16%.
[0040] Example 2
[0041] A method for the electrocatalytic reduction of chlorate using a cathode electrode was conducted under different pH conditions of chlorate solutions. A 36-hour reduction experiment was performed using a separate tank at an initial chlorate molar concentration of 1 mM, pH values ranging from 1 to 4, and a reduction voltage of 3 V. The results are as follows: Figure 4 As shown, the chlorate reduction rate is as high as 98.24% when the pH is 2, decreases to 91.04% when the pH is 1, and is only 3.95% when the pH is increased to 4.
[0042] Example 3
[0043] A method for the electrocatalytic reduction of chlorate using a cathode electrode is carried out under different chlorate solution concentrations, with chlorate solution concentrations ranging from 0.5 to 50 mM, pH 2, and a reduction voltage of 3 V. Figure 5 As shown, during the 36-hour electrolysis process, the absolute removal rates of chlorate solutions at 0.5, 1, 10, and 50 mM were 99.19%, 98.24%, 83.94%, and 55.31%, respectively.
[0044] Example 4
[0045] like Figure 6 As shown, under the conditions of pH 2.0, reduction voltage 3 V, chlorate concentration 1 mM, and reduction current 12 mA, chlorate can be reduced in Pd / C-MoO₂. X The chloride ions are effectively reduced and completely converted on the / MF electrode, with a reduction rate of up to 98.24%.
[0046] Example 5
[0047] like Figure 7 As shown, under the conditions of a reduction voltage of 3 V, an initial solution pH of 2, and a reduction voltage of 3 V, bromide ions reduced the reduction rate to 91.32%, and chloride ions reduced the reduction rate to 88.89%. When NO3... - The reduction rate is only 81.38% in its presence, which is due to its interaction with ClO3. - This is due to competition for active sites, and NO3... - The fact that it itself is almost completely reduced indicates that Pd / C-MoO X / MF for ClO3 - Selective reduction.
[0048] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims
1. A method for preparing a cathode electrode for the electrocatalytic reduction of chlorate, characterized in that: Includes the following steps: S1. Cut the high-purity molybdenum foil into 50 mm × 25 mm × 0.2 mm sheets, place them in anhydrous ethanol and sonicate for 10 min, then place them in ultrapure water and sonicate for 10 min to remove surface organic matter and impurities. S2. Prepare a 1 mol / L phosphoric acid solution in a 250 mL volumetric flask. Weigh 0.4625 g of ammonium fluoride and add it to the phosphoric acid solution. Stir until homogeneous. This solution will be used as the electrolyte in this experiment. S3. Take 200 mL of electrolyte and pour it into the electrolytic cell. Use high-purity molybdenum foil as the working electrode and Pt sheet as the counter electrode. Make the distance between the two electrodes 1.5 cm and ensure that they are in full contact with the electrolyte at the same time. Apply a voltage of 0.3 V using a constant voltage power supply for 15 min. S4. After the reaction is complete, the anode is removed, washed with ethanol, and then vacuum dried at 45°C for 12 hours to obtain MoO2 grown on molybdenum foil. X Oxide layer, denoted as MoO X / MF; S5. Disperse 10 mg of 10% Pd / C in 950 μl of isopropanol, add 50 μl of Nafion solution, sonicate for 20 min to form black ink, and uniformly drop it onto MoO2. X Pd / C-MoO was obtained by vacuum drying at 45°C for 12 h on / MF. X / MF electrode.
2. A cathode electrode prepared by the method described in claim 1 for electrocatalytic reduction of chlorate, comprising the following steps: S1. In the segmented electrochemical reactor, the reactor is divided into a cathode tank and an anode tank by a proton exchange membrane. The cathode tank is 400 mL, and the anode tank is 200 mL. S2, The anode is an iridium-tantalum / titanium electrode, and the cathode is a Pd / C-MoO electrode. X / MF electrode, with an effective area of 10 cm² for both anode and cathode. 2 The geometric surface area is 10 cm². 2 The distance between the anode and cathode is 20mm; S3. Add 170 mL of ultrapure water to the anode tank and 340 mL of 1 mM chlorate solution to the cathode tank. Then, add 1 M H2SO4 dropwise to adjust the pH of the solution to below 2. Stir with a magnetic stirrer until the solution is evenly distributed. The experiment is carried out under an external constant pressure of 3-6 V.