A method for preparing a reactive electrochemical membrane electrode

Abstract

The invention relates to the technical field of electrochemical oxidation and discloses a preparation method of a reactive electrochemical membrane electrode. The method comprises the following steps: mixing Ti4O7 and a pore-forming agent, drying, and pressing to obtain a green body; sintering the green body to obtain a sintered body; boiling the sintered body in water, removing the pore-forming agent, and drying to obtain a porous Ti4O7 electrode; immersing the porous Ti4O7 electrode in a solution containing Ce(NO3)3·6H2O, evaporating the solution, and obtaining a treated electrode; calcining the treated electrode to obtain a CeO2-Ti4O7 electrode; immersing the CeO2-Ti4O7 electrode in an aqueous solution of H2PtCl6·6H2O to obtain a soaked electrode, and performing heat treatment to obtain a Pt / CeO2-Ti4O7 electrode. The electrode has high charge and mass transfer efficiency and reduces energy consumption during electrochemical oxidation.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical oxidation, in particular to a method for preparing a reactive electrochemical membrane electrode. Background Art

[0002] Disinfectant wastewater is a difficult point in current sewage treatment. Electrochemical oxidation technology has the advantages of high integration, easy operation, high treatment effect and no secondary pollution.

[0003] Reactive electrochemical membrane (REM) technology, built on a porous anode in a flow-through mode, can be used to improve the electrooxidation efficiency of organic pollutants. Pollutant electrooxidation occurs in a thin region (less than 1 μm) on or near the anode surface. Therefore, the degradation efficiency of target compounds in parallel-plate batch reactors is often limited by the slow interphase mass transfer from the bulk solution to the reaction zone. REMs, with their three-dimensional porous structure, can significantly increase the mass transfer rate by inducing solution convection through their microporous structure, which also helps to generate more electrooxidation reaction sites.

[0004] Compared to the currently dominant BDD electrode material, Ti4O7 offers similarly excellent electrochemical performance while also offering significant cost advantages. In particular, Ti4O7-based REMs operating in a single filtration process have been widely demonstrated to remove a wide range of organic pollutants, including herbicides, landfill leachate, phenolic compounds, perfluorinated compounds, and antibiotics.

[0005] Due to the influence of electrode resistance and solution impedance, the potential distribution of REM inevitably decays inward along the surface. The depth at which the potential decays to the threshold for ·OH generation is even less than 1% of the depth at which the DET reaction occurs, that is, the DET reaction may play a more important role in the REM treatment of organic pollutants. Titanium suboxide materials with low production costs, especially Ti4O7, can meet the performance requirements of REM treatment. However, the relatively low interfacial charge transfer rate of pure Ti4O7 severely limits its electrooxidation efficiency and generates excessive energy consumption. Therefore, strategies to enhance the interfacial charge transfer of Ti4O7 REM are desirable, especially for surface modification with elemental and / or material loading.

[0006] Ti4O7 modified with carbonaceous materials or MXene can effectively improve the interfacial electron transfer efficiency, electroactive epitopes and adsorption capacity for water pollutants, promoting the electrooxidation process of target compounds. However, the relatively poor structural stability and / or strong anodic polarization of these supported materials during high-temperature sintering, as well as the potential membrane fouling problem with enhanced adsorption capacity, limit the application and promotion of their REM operation. Noble metal loading can circumvent the above problems and achieve effective performance improvements. For example, amorphous palladium clusters have been shown to accelerate the electrooxidation kinetics of perfluorooctanoic acid by enhancing its electron transfer on the Ti4O7 anode. However, the supported metals generally tend to aggregate on the substrate due to their high surface energy, resulting in low atomic utilization and reducing the total surface energy of the system.

[0007] Therefore, there is an urgent need for a method for preparing a reactive electrochemical membrane electrode to solve the above technical problems. Summary of the Invention

[0008] The present invention aims to solve the technical problems of low charge and mass transfer efficiency of existing Ti4O7 electrodes and high energy consumption and low efficiency of existing electrochemical oxidation technologies, and to provide a method for preparing a reactive electrochemical membrane electrode. A new Ti4O7-based electrode is constructed by a co-loading method of Pt and carrier oxides to improve the electrooxidation efficiency of organic pollutants.

[0009] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0010] A method for preparing a reactive electrochemical membrane electrode comprises the following steps:

[0011] S1, Preparation of porous Ti4O7 electrode:

[0012] Ti4O7 and a pore-forming agent are mixed, dried, and pressed to obtain a green body; the green body is sintered to obtain a sintered body; the sintered body is boiled in water, the pore-forming agent is removed, and then dried to obtain a porous Ti4O7 electrode;

[0013] S2, Preparation of CeO2-Ti4O7 Electrode:

[0014] Immersing the porous Ti4O7 electrode obtained in step S1 in a solution containing Ce(NO3)3·6H2O for a period of time, then evaporating the solution to obtain a treated electrode; calcining the treated electrode to obtain a CeO2-Ti4O7 electrode;

[0015] S3, Preparation of Pt / CeO2-Ti4O7 Electrode:

[0016] The CeO2-Ti4O7 electrode is immersed in an aqueous solution of H2PtCl6·6H2O for a period of time to obtain a soaked electrode; the soaked electrode is dried and then heat-treated to obtain a Pt / CeO2-Ti4O7 electrode.

[0017] Specifically, in the prepared Pt / CeO2-Ti4O7 electrode, the loading amount of Pt is 0.25 to 4.09 wt.% of the mass of Ti4O7.

[0018] Preferably, in step S1, the mass ratio of Ti4O7 to the pore-forming agent is 3:0.5-1.5; the sintering temperature is 1200°C, and the sintering time is 2 hours.

[0019] Preferably, in step S1, the sintering procedure is as follows: the heating rate from room temperature to 1000°C is 10°C / min, the heating rate from 1000°C to 1200°C is 5°C / min, and the temperature is kept at 1200°C for 2 hours; the vacuum degree is kept at 10°C / min during the sintering process. -2 Below Pa.

[0020] Preferably, in step S1, the pore-forming agent is NaCl.

[0021] Specifically, Ti4O7 and the pore-forming agent are wet-mixed in a planetary ball mill; the wet-mixing time is 6 hours.

[0022] Preferably, in step S2, the mass ratio of the porous Ti4O7 electrode to Ce(NO3)3·6H2O is 4.5:0.1-1.

[0023] Preferably, in step S2, the evaporation temperature of the evaporated solution is 70°C; the calcination temperature is 300°C, and the calcination time is 2 hours.

[0024] Specifically, after the porous Ti4O7 electrode is immersed in a solution containing Ce(NO3)3·6H2O, the Ce(NO3)3·6H2O solution immersed in the porous Ti4O7 electrode is placed in a vacuum environment for 30 minutes.

[0025] Preferably, in step S3, the CeO2-Ti4O7 electrode is calculated as Ti4O7, and the amount of H2PtCl6·6H2O used is calculated as Pt, and their mass ratio is 4.5:0.01126~0.1842; the mass volume ratio of the CeO2-Ti4O7 electrode is calculated as Ti4O7 to the aqueous solution of H2PtCl6·6H2O is 4.5:60, and the unit of mass volume is g:mL.

[0026] Specifically, the relative molecular mass of H2PtCl6·6H2O is 517.8, and the relative atomic mass of Pt is 195.1; the amount of H2PtCl6·6H2O used is calculated based on the mass of H2PtCl6·6H2O itself, and the result is: in the step S3, the mass ratio of CeO2-Ti4O7 electrode, calculated as Ti4O7, to H2PtCl6·6H2O is 4.5:0.0299~0.4889.

[0027] Preferably, in step S3, the heat treatment time is 2 hours, the heat treatment temperature is 500°C, and the vacuum degree during the heat treatment is less than 10 -2 Pa.

[0028] Specifically, after the CeO2-Ti4O7 electrode is immersed in the H2PtCl6·6H2O aqueous solution, the H2PtCl6·6H2O aqueous solution in which the CeO2-Ti4O7 electrode is immersed is placed in a vacuum environment for 30 minutes to allow the solution to enter the interior of the electrode.

[0029] Specifically, the following steps are included:

[0030] S1, Preparation of porous Ti4O7 electrode:

[0031] First, 4.5g of Ti4O7 powder and 0.75-2.25g of pore-forming agent NaCl were wet-mixed in a planetary ball mill for 6h, and then dried and pressed (10Mpa) to obtain a green body with a diameter of 30mm. The green body was then sintered in a vacuum sintering furnace to obtain a sintered body; the sintering procedure was: heating rate from room temperature to 1000℃ at 10℃ / min, heating rate from 1000℃ to 1200℃ at 5℃ / min and holding at 1200℃ for 2 hours. The vacuum degree was maintained at 10 -2 The obtained sintered body was boiled in boiling water for 5 hours to remove residual NaCl, and then dried to obtain a porous Ti4O7 electrode.

[0032] S2, Preparation of CeO2-Ti4O7 Electrode:

[0033] The porous Ti4O7 electrode prepared in step S1 was immersed in a solution containing 0.1-1 g of Ce(NO3)3·6H2O. Subsequently, the solution and the electrode were kept under vacuum conditions for 30 minutes, and then the solution was evaporated at 70°C. The treated electrode was then placed in a muffle furnace and calcined at 300°C for 2 hours (heating rate of 5°C / min) to obtain a CeO2-Ti4O7 electrode.

[0034] S3, Preparation of Pt / CeO2-Ti4O7 Electrode:

[0035] Take 1g of H2PtCl6·6H2O and dissolve it in 100mL of deionized water. Then take 2.99~48.89mL (based on the mass fraction of Pt in Ti4O7 being 0.25~4.09wt.%) of the liquid and dilute it to 60mL. Then immerse CeO2-Ti4O7 in the solutions with different Pt contents. Keep it under vacuum for 30 minutes to allow the solution to enter the interior of the electrode. Then, dry the electrode at 70℃. Then, at less than 10 -2 The electrode was heat-treated at 500 °C for 2 h under a vacuum of 1.5 Pa to obtain a Pt / CeO2-Ti4O7 electrode.

[0036] Working principle:

[0037] Strong metal-support interactions can modulate the chemical potential of electrode materials. The interfacial structure determines the electrooxidation efficiency, and the rational design and introduction of well-distributed and dense metal monomers on the Ti4O7 electrode surface using such supports remains challenging. Pt nanoclusters and even single Pt atoms have been used to prepare heterogeneous catalysts to achieve high catalytic activity through faster charge transfer. A typical example is that Pt clusters of different sizes stabilized on high-surface-area supports increase the activity of propane oxidative dehydrogenation by 40-100 times. Therefore, the strong interaction between Pt atoms and supported oxides prevents the aggregation of Pt atoms to promote the electrooxidation efficiency of Ti4O7 REM.

[0038] The key point of this invention is to utilize the anchoring effect of CeO2 on Pt, so that Pt can be evenly and densely distributed on the Ti4O7 electrode. In addition, the addition of CeO2 can promote electron transfer from Pt to the Ti4O7 substrate material, thereby increasing the charge and mass transfer efficiency of the composite electrode.

[0039] Beneficial Effects: The present invention utilizes the anchoring effect of CeO2 on Pt, enabling a uniform and dense distribution of Pt on the Ti4O7 electrode. The addition of CeO2 promotes electron transfer from Pt to the Ti4O7 substrate, thereby increasing the charge and mass transfer efficiency of the composite electrode. The resulting Pt / CeO2-Ti4O7 electrode exhibits high charge and mass transfer efficiency, reducing energy consumption during electrochemical oxidation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The degradation effects of Ti4O7 electrode and 0.25Pt / CeO2-Ti4O7 electrode on DCP in batch mode;

[0041] Figure 2 The degradation effects of Ti4O7 electrode and 0.25Pt / CeO2-Ti4O7 electrode on DCP under REM mode;

[0042] Figure 3 The degradation effects of Ti4O7 electrode and 0.5Pt / CeO2-Ti4O7 electrode on DCP in batch mode;

[0043] Figure 4 The degradation effects of Ti4O7 electrode and 0.5Pt / CeO2-Ti4O7 electrode on DCP under REM mode;

[0044] Figure 5 The degradation effects of Ti4O7 electrode and 1Pt / CeO2-Ti4O7 electrode on DCP in batch mode;

[0045] Figure 6 This is the degradation effect of Ti4O7 electrode and 1Pt / CeO2-Ti4O7 electrode on DCP under REM mode. DETAILED DESCRIPTION

[0046] The present invention will be further described below with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are intended to explain the present invention but are not intended to limit the present invention.

[0047] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0048] There is no particular limitation on the purity of all raw materials in the present invention, and the present invention preferably adopts conventional purity used in the art.

[0049] The devices used in the present invention are not particularly limited and can be devices commonly used in the art.

[0050] Example 1

[0051] A method for preparing a reactive electrochemical membrane electrode comprises the following steps:

[0052] First, 4.5 g of Ti4O7 powder and 1.5 g of pore former NaCl were wet-mixed in a planetary ball mill for 6 h, and then dried and pressed (10 MPa) to obtain a green body with a diameter of 30 mm. The green body was then sintered in a vacuum sintering furnace with the following sintering procedures: heating from room temperature to 1000 ° C at a rate of 10 ° C / min, heating from 1000 ° C to 1200 ° C at a rate of 5 ° C / min and holding at 1200 ° C for 2 hours; vacuum was maintained at 10 -2 The sintered body was boiled in boiling water for 5 hours to remove residual NaCl, and then dried to obtain a Ti4O7 electrode.

[0053] The prepared Ti4O7 electrode was immersed in a solution containing 0.5975 g of Ce(NO3)3·6H2O. Subsequently, the solution and the electrode were kept under vacuum conditions for 30 minutes, and then the solution was evaporated at 70°C. The treated electrode was then placed in a muffle furnace and calcined at 300°C for 2 hours (heating rate of 5°C / min) to obtain a CeO2-Ti4O7 electrode.

[0054] Dissolve 1g of H2PtCl6·6H2O in 100mL of deionized water. Then dilute 2.99mL (based on the mass fraction of Pt in Ti4O7, a Pt loading of 0.25wt.%) of the solution to 60mL. Immerse CeO2-Ti4O7 in the solution separately. Maintain vacuum conditions for 30 minutes to allow the solution to penetrate the interior of the electrode. Then, dry the electrode at 70°C. -2 Pa vacuum, the electrode was heat treated at 500 ° C for 2 hours to obtain a Pt / CeO2-Ti4O7 electrode, which was recorded as 0.25Pt / CeO2-Ti4O7 electrode (0.25 means the mass fraction of Pt in Ti4O7 is 0.25wt%).

[0055] The 0.25Pt / CeO2-Ti4O7 electrode was used to degrade DCP. The results of the Batch system and REM system are shown in Figure 2. Figure 1 、 Figure 2 Parameters: Batch mode (current density: 5mA cm -2 , electrolyte solution: 50 mM NaH2PO4, cathode-anode distance 2 cm, room temperature); in REM mode (current density: 1-5 mA cm -2 , electrolyte solution: 50 mM NaH2PO4, distance between cathode and anode 2 cm, room temperature).

[0056] Example 2

[0057] A method for preparing a reactive electrochemical membrane electrode comprises the following steps:

[0058] First, 4.5 g of Ti4O7 powder and 1.5 g of pore former NaCl were wet-mixed in a planetary ball mill for 6 h, and then dried and pressed (10 MPa) to obtain a green body with a diameter of 30 mm. The green body was then sintered in a vacuum sintering furnace with the following sintering program: heating from room temperature to 1000 ° C at a rate of 10 ° C / min, heating from 1000 ° C to 1200 ° C at a rate of 5 ° C / min and holding at 1200 ° C for 2 hours. The vacuum degree was maintained at 10 -2 The sintered body was boiled in boiling water for 5 hours to remove residual NaCl, and then dried to obtain a Ti4O7 electrode.

[0059] The prepared Ti4O7 electrode was immersed in a solution containing 0.5975 g of Ce(NO3)3·6H2O. Subsequently, the solution and the electrode were kept under vacuum conditions for 30 minutes, and then the solution was evaporated at 70°C. The treated electrode was then placed in a muffle furnace and calcined at 300°C for 2 hours (heating rate of 5°C / min) to obtain a CeO2-Ti4O7 electrode.

[0060] Dissolve 1g of H2PtCl6·6H2O in 100mL of deionized water. Then, dilute 5.97mL (0.5wt.% Pt loading based on the mass fraction of Pt in Ti4O7) to 60mL. Immerse CeO2-Ti4O7 in the solution. Maintain vacuum for 30 minutes to allow the solution to penetrate the interior of the electrode. Then, dry the electrode at 70°C. - 2 Pa vacuum, the electrode was heat treated at 500 ° C for 2 hours to obtain a Pt / CeO2-Ti4O7 electrode, which was recorded as 0.5Pt / CeO2-Ti4O7 electrode (0.5 means the mass fraction of Pt in Ti4O7 is 0.5wt%).

[0061] The 0.5Pt / CeO2-Ti4O7 electrode was used to degrade DCP. The results of the Batch system and REM system are shown in Figure 2. Figure 3 、 Figure 4 Parameters: Batch mode (current density: 5mA cm -2 , electrolyte solution: 50 mM NaH2PO4, distance between cathode and anode 2 cm, room temperature); in REM mode (current density: 1-5 mA cm -2 , electrolyte solution: 50 mM NaH2PO4, distance between cathode and anode 2 cm, room temperature).

[0062] Example 3

[0063] A method for preparing a reactive electrochemical membrane electrode comprises the following steps:

[0064] First, 4.5 g of Ti4O7 powder and 1.5 g of pore former NaCl were wet-mixed in a planetary ball mill for 6 h, and then dried and pressed (10 MPa) to obtain a green body with a diameter of 30 mm. The green body was then sintered in a vacuum sintering furnace with the following sintering program: heating from room temperature to 1000 ° C at a rate of 10 ° C / min, heating from 1000 ° C to 1200 ° C at a rate of 5 ° C / min and holding at 1200 ° C for 2 hours. The vacuum degree was maintained at 10 -2The sintered body was boiled in boiling water for 5 hours to remove residual NaCl, and then dried to obtain a Ti4O7 electrode.

[0065] The prepared Ti4O7 electrode was immersed in a solution containing 0.5975 g of Ce(NO3)3·6H2O. Subsequently, the solution and the electrode were kept under vacuum conditions for 30 minutes, and then the solution was evaporated at 70°C. The treated electrode was then placed in a muffle furnace and calcined at 300°C for 2 hours (heating rate of 5°C / min) to obtain a CeO2-Ti4O7 electrode.

[0066] Dissolve 1g of H2PtCl6·6H2O in 100mL of deionized water. Then dilute 11.95mL (based on the mass fraction of Pt in Ti4O7, 1wt.% Pt loading) of the solution to 60mL. Immerse CeO2-Ti4O7 in the solution. Maintain vacuum for 30 minutes to allow the solution to penetrate the interior of the electrode. Then, dry the electrode at 70°C. - 2 Pa vacuum, the electrode was heat treated at 500 ° C for 2 hours to obtain a Pt / CeO2-Ti4O7 electrode, which was recorded as 1Pt / CeO2-Ti4O7 electrode (1 means the mass fraction of Pt in Ti4O7 is 1wt%).

[0067] The 1Pt / CeO2-Ti4O7 electrode was used to degrade DCP. The results of the Batch system and REM system are shown in Figure 2. Figure 5 、 Figure 6 Parameters: Batch mode (current density: 5mA cm -2 , electrolyte solution: 50 mM NaH2PO4, distance between cathode and anode 2 cm, room temperature); in REM mode (current density: 1-5 mA cm -2 , electrolyte solution: 50 mM NaH2PO4, distance between cathode and anode 2 cm, room temperature).

[0068] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. Any technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a reactive electrochemical membrane electrode, characterized in that: The following steps are involved: S1, Preparation of porous Ti4O7 electrode: Ti4O7 and a pore-forming agent are mixed, dried, and pressed to obtain a green body; the green body is sintered to obtain a sintered body; the sintered body is boiled in water, the pore-forming agent is removed, and then dried to obtain a porous Ti4O7 electrode; S2, Preparation of CeO2-Ti4O7 Electrode: Immersing the porous Ti4O7 electrode obtained in step S1 in a solution containing Ce(NO3)3·6H2O for a period of time, then evaporating the solution to obtain a treated electrode; calcining the treated electrode to obtain a CeO2-Ti4O7 electrode; S3, Preparation of Pt / CeO2-Ti4O7 Electrode: The CeO2-Ti4O7 electrode is immersed in an aqueous solution of H2PtCl6·6H2O for a period of time to obtain a soaked electrode; the soaked electrode is dried and then heat-treated to obtain a Pt / CeO2-Ti4O7 electrode.

2. The method for preparing a reactive electrochemical membrane electrode according to claim 1, wherein: In step S1, the mass ratio of Ti4O7 to the pore-forming agent is 3:0.5-1.5; the sintering temperature is 1200°C, and the sintering time is 2 hours.

3. The method for preparing a reactive electrochemical membrane electrode according to claim 1, wherein: In step S1, the sintering procedure is as follows: the heating rate from room temperature to 1000°C is 10°C / min, the heating rate from 1000°C to 1200°C is 5°C / min, and the temperature is kept at 1200°C for 2 hours; the vacuum degree is kept at 10°C / min during the sintering process. -2 Below Pa.

4. The method for preparing a reactive electrochemical membrane electrode according to claim 1, wherein: In the step S1, the pore-forming agent is NaCl.

5. The method for preparing a reactive electrochemical membrane electrode according to claim 1, wherein: In the step S2, the mass ratio of the porous Ti4O7 electrode to Ce(NO3)3·6H2O is 4.5:0.1-1.

6. The method for preparing a reactive electrochemical membrane electrode according to claim 1, wherein: In the step S2, the evaporation temperature of the evaporated solution is 70°C; the calcination temperature is 300°C, and the calcination time is 2 hours.

7. The method for preparing a reactive electrochemical membrane electrode according to claim 1, wherein: In step S3, the CeO2-Ti4O7 electrode is calculated as Ti4O7, and the H2PtCl6·6H2O is used as Pt, with a mass ratio of 4.5:0.01126-0.1842; the mass volume ratio of the CeO2-Ti4O7 electrode is calculated as Ti4O7 to the H2PtCl6·6H2O aqueous solution is 4.5:60, and the unit of mass volume is g:mL.

8. The method for preparing a reactive electrochemical membrane electrode according to claim 1, wherein: In step S3, the heat treatment time is 2 hours, the heat treatment temperature is 500°C, and the vacuum degree during the heat treatment is less than 10 -2 Pa.

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