A self-breathing anti-fouling cathode, a preparation method thereof, an electrolytic cell and application thereof

Abstract

The application provides a self-breathing anti-fouling cathode, a preparation method thereof, an electrolytic cell and application thereof, and belongs to the technical field of electrochemical electrodes. The preparation method comprises the following steps: mixing a carbon substrate and a catalyst precursor solution, performing first calcination on the mixed solution in a protective atmosphere to obtain an anti-fouling cathode; and performing second calcination on the anti-fouling cathode after spraying a hydrophobic agent on the anti-fouling cathode in an oxygen-containing atmosphere to obtain a self-breathing anti-fouling cathode. The self-breathing anti-fouling cathode can improve the oxygen mass transfer efficiency and inhibit the deposition of Ca 2+ , Mg 2+ and other divalent ions, significantly enhances the hydrogen peroxide generation capacity, and improves the long-term operation stability; on the other hand, the self-breathing anti-fouling cathode has a spatial hydrophobic microenvironment, improves the H2O2 yield without the need of external air ventilation; and the design of the hydrophobic anode reduces the decomposition of H2O2 at the anode, realizes efficient and stable electro-synthesis of H2O2, and is used for pollutant degradation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical electrode, and particularly relates to a self-breathing anti-fouling cathode, a preparation method thereof, an electrolytic tank and application thereof. BACKGROUND

[0002] Hydrogen peroxide (H2O2) is widely used in papermaking, wastewater treatment, medicine, textile and other fields as an excellent oxidant. The traditional anthraquinone method for synthesizing H2O2 in industrial production has complex process, serious pollution and high energy consumption. Based on 2e - transfer path, the driving oxygen reduction reaction (2e - ORR) for preparing H2O2 has the advantages of mild operating conditions, low voltage directly provided by renewable energy, rich oxygen raw materials, high product selectivity and high yield, and is considered as the frontier direction of electrochemical synthesis of H2O2.

[0003] However, the problem of direct anodic oxidation degradation of H2O2 in the membraneless electrolytic tank seriously limits the practical application and efficiency improvement of the technology, so that it is a key challenge to maintain high concentration of H2O2 in the membraneless electrochemical system. In addition, the fouling problem of the electrode surface further restricts the long-term stability, which is mainly caused by the deposition of Ca 2+ , Mg 2+ and other divalent ions in the wastewater and the blocking of active sites caused by the local high alkalinity environment of the cathode, which finally causes significant attenuation of the H2O2 generation efficiency.

[0004] Therefore, how to inhibit the decomposition of H2O2 and alleviate the electrode fouling is a core problem to be solved for realizing efficient and stable electrochemical synthesis of H2O2. SUMMARY

[0005] The present application aims at the deficiencies of the prior art to provide a self-breathing anti-fouling cathode, a preparation method thereof, an electrolytic tank and application thereof.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions.

[0007] The present application provides a preparation method of a self-breathing anti-fouling cathode, comprising the following steps:

[0008] 1) mixing a carbon substrate and a catalyst precursor solution, and performing first calcination on the mixed solution under a protective atmosphere to obtain an anti-fouling cathode;

[0009] 2) performing second calcination on the anti-fouling cathode after spraying a hydrophobic agent in an oxygen-containing atmosphere to obtain a self-breathing anti-fouling cathode;

[0010] The catalyst precursor solution is composed of a catalyst, a conductive agent, a binder solution, a surfactant solution, a scale inhibitor solution and a dispersant; the mass ratio of the catalyst, the conductive agent, the binder solution, the surfactant solution, the scale inhibitor solution and the dispersant is 1:0.25-2:0.1-1.25:0.1-2.4:0.2-2:10-100;

[0011] The hydrophobic agent is polytetrafluoroethylene, methyltrimethoxysilane or polydimethylsiloxane, and the spraying amount of the hydrophobic agent is 0.05-1.0 mg / cm 2 .

[0012] Preferably, the catalyst is prepared by dispersing carbon black in a sodium hydroxide solution for hydrothermal reaction.

[0013] The mass-volume ratio of the carbon black and the sodium hydroxide solution is 1 g:600-900 mL, and the concentration of the sodium hydroxide solution is 0.1-12 mol / L; the temperature of the hydrothermal reaction is 150-200°C, and the time of the hydrothermal reaction is 6-18 h.

[0014] Preferably, the conductive agent is carbon nanotube, carbon black, graphite, graphene or reduced graphene oxide.

[0015] The binder solution is one or two of polyvinylidene fluoride solution, polytetrafluoroethylene solution and basic ionomer solution; the mass fraction of the basic ionomer solution is 5-20%, and the mass fraction of the polytetrafluoroethylene solution and the polyvinylidene fluoride solution is independently 10-60%;

[0016] The mass fraction of the surfactant solution is 5-30%, and the surfactant is one or two of polyvinyl alcohol, polyvinylpyrrolidone, sodium dodecyl sulfonate, fatty alcohol polyoxyethylene ether and polyethylene glycol;

[0017] The mass fraction of the scale inhibitor solution is 5-50%, and the scale inhibitor is polyphosphate sodium, organic phosphonate, polyacrylic acid sodium, polyepoxysuccinic acid, polymaleic anhydride or polyaspartic acid;

[0018] The dispersant is composed of water and an organic solvent, and the organic solvent is ethanol, isopropyl alcohol, methanol, glycerol, pentanediol, n-butanol or acetic acid; in the dispersant, the mass fraction of water is 25-80%.

[0019] Preferably, the mixing method in step 1) is ultrasonic, immersion or electrophoretic adsorption; the protective atmosphere is argon or nitrogen; and the oxygen-containing atmosphere in step 2) is high-purity oxygen, air or carbon dioxide.

[0020] Preferably, in the first calcination of step 1) and the second calcination of step 2), the temperature of the calcination is independently 250-500℃, the time of the calcination is independently 0.5-2.5h, and the heating rate to the calcination temperature is independently 2-10℃ / min.

[0021] The application also provides a self-breathing anti-fouling cathode prepared by the preparation method.

[0022] The application also provides an electrolytic cell comprising the self-breathing anti-fouling cathode, which comprises an anode end plate 1, a hydrophobic anode 2, an electrolyte flow-through cavity 4, the self-breathing anti-fouling cathode 5, a hollow current collector 6, and a cathode end plate 7.

[0023] The hydrophobic anode 2 is assembled to the anode end plate 1 through an anode lug mounting hole 11; the self-breathing anti-fouling cathode 5 is quickly engaged with the hollow current collector 6 and is embedded into the cathode end plate 7 through a cathode lug mounting hole 71; the electrolyte flow-through cavity 4 is provided with a reaction through hole communicating the anode end plate 1 and the cathode end plate 7.

[0024] The cathode end plate 7 is of a hollow structure.

[0025] Preferably, the preparation method of the hydrophobic anode is as follows:

[0026] The titanium substrate is sequentially subjected to constant current electrodeposition and first calcination to obtain an anode electrode; the anode electrode is sequentially sprayed with a hydrophobic agent and subjected to second calcination to obtain the hydrophobic anode.

[0027] The electrolyte for the constant current electrodeposition comprises a metal precursor and a solvent, the metal precursor is chloroiridic acid and ruthenium chloride, the molar ratio of the chloroiridic acid and the ruthenium chloride is 1:0.2-3, the solvent is one or two of methanol, ethanol, isopropanol and n-butanol, and the concentration of the metal precursor in the electrolyte is 0.1-0.5mol / L.

[0028] Preferably, the temperature of the constant current electrodeposition is 1-10℃, the current density is 5-50mA / cm 2 , and the time is 10-40min.

[0029] The temperature of the first calcination is 400-500℃, the time is 0.5-2h, the heating rate to the first calcination temperature is 2-10℃ / min, the temperature of the second calcination is 250-500℃, the time is 0.5-2.5h, and the heating rate to the second calcination temperature is 2-10℃ / min.

[0030] The hydrophobic agent is polytetrafluoroethylene, methyltrimethoxysilane or polydimethylsiloxane, and the spraying amount of the hydrophobic agent is 0.05-1.0mg / cm2 .

[0031] The application also provides the use of the electrolytic cell in degrading and removing pollutants in water bodies.

[0032] The beneficial effects of the application are:

[0033] 1) The electrolytic cell of the application adopts a membrane-free design to reduce energy consumption and cost. On the one hand, the self-breathing anti-fouling cathode improves the oxygen mass transfer efficiency and inhibits the deposition of Ca 2+ , Mg 2+ and other divalent ions, significantly enhancing the hydrogen peroxide generation capacity and improving the long-term operation stability. On the other hand, the hydrophobic microenvironment has a space to improve the production of H2O2 without the need for external air ventilation. At the same time, the design of the hydrophobic anode reduces the decomposition of H2O2 at the anode, realizing efficient and stable electro-synthesis of H2O2 for pollutant degradation.

[0034] 2) The electrolytic cell with a threaded inner buckle structure design realizes the replacement of the self-breathing anti-fouling cathode, which has significant practical advantages. First, the modular electrode structure allows quick replacement of the inactivated cathode, which greatly shortens the system downtime maintenance time compared to the traditional fixed electrode, ensures the continuity of the process, reduces the operating cost, and does not affect the anode and other components. Second, the electrolytic cell of the application allows flexible matching of the optimal anti-fouling cathode material (such as catalyst loading) according to the water quality characteristics (such as hardness and organic matter content), realizing dynamic optimization of H2O2 yield and pollutant removal efficiency. This innovative design not only improves the economy and adaptability of the system, but also provides a key solution for commercialization. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 Linear sweep voltammetry curve of the self-breathing anti-fouling cathode prepared under different conditions for Example 1 and Comparative Examples 1-2;

[0036] Figure 2 The amount of hydrogen peroxide generated (a), Faraday efficiency (b) and fouling amount (c) of the self-breathing anti-fouling cathode prepared under different conditions for Example 1 and Comparative Examples 1-2 before and after reaction;

[0037] Figure 3 Schematic diagram of the electrolytic cell using the self-breathing anti-fouling cathode prepared in Example 1 for Application Example 1; wherein 1 is an anode end plate, 2 is a hydrophobic anode, 3 is a first gasket, 4 is an electrolyte flow cavity, 5 is a self-breathing anti-fouling cathode, 6 is a hollow current collector, 7 is a cathode end plate, 11 is an anode terminal post mounting hole, 12 is an anode internal thread structure, 31 is a second gasket, 32 is a third gasket, 41 is an electrolyte inlet, 42 is an electrolyte outlet, 43 is an external thread interface, 71 is a cathode terminal post mounting hole, and 72 is a cathode internal thread structure.

[0038] Figure 4 The self-breathing anti-fouling cathode prepared by the method of the present application was used in the electrolytic cell of application examples 1-2, and the hydrogen peroxide production (a), faradic efficiency (b) and pollutant removal (c) were measured after continuous reaction at 100 mA / cm 2 at 100 mA / cm DETAILED DESCRIPTION

[0039] The present application provides a method for preparing a self-breathing anti-fouling cathode, comprising the following steps:

[0040] 1) mixing a carbon substrate and a catalyst precursor solution, and performing first calcination on the mixture under a protective atmosphere to obtain an anti-fouling cathode;

[0041] 2) performing second calcination on the anti-fouling cathode after spraying a hydrophobic agent thereon under an oxygen-containing atmosphere to obtain a self-breathing anti-fouling cathode;

[0042] In step 1), the catalyst precursor solution is composed of a catalyst, a conductive agent, a binder solution, a surfactant solution, an anti-fouling agent solution and a dispersant, and the mass ratio of the catalyst, the conductive agent, the binder solution, the surfactant solution, the anti-fouling agent solution and the dispersant is 1:0.25-2:0.1-1.25:0.1-2.4:0.2-2:10-100.

[0043] In step 2), the hydrophobic agent is polytetrafluoroethylene, methyltrimethoxysilane or polydimethylsiloxane, and the spraying amount of the hydrophobic agent is 0.05-1.0 mg / cm 2 .

[0044] In the present application, the mass ratio of the catalyst, the conductive agent, the binder solution, the surfactant solution, the anti-fouling agent solution and the dispersant is preferably 1:0.5-1.5:0.25-1:0.5-2:0.5-1.5:20-90, further preferably 1:0.8-1.2:0.4-0.9:0.8-1.5:0.75-1.2:30-80, and more preferably 1:1:0.7-0.8:1-1.2:1:50.

[0045] In the present application, the preparation method of the catalyst is preferably as follows: dispersing carbon black in a sodium hydroxide solution to perform hydrothermal reaction.

[0046] The mass-volume ratio of the carbon black and the sodium hydroxide solution is preferably 1g:600-900mL, further preferably 1g:650-850mL, more preferably 1g:700-800mL, and the concentration of the sodium hydroxide solution is preferably 0.1-12mol / L, further preferably 1-10mol / L, more preferably 3-7mol / L; the temperature of the hydrothermal reaction is preferably 150-200℃, further preferably 160-190℃, more preferably 170-180℃, and the time of the hydrothermal reaction is preferably 6-18h, further preferably 8-15h, more preferably 10-12h.

[0047] In the present application, the product of the hydrothermal reaction is preferably cleaned with ethanol until the supernatant is neutral, and then sequentially subjected to suction filtration and drying; the vacuum degree of the suction filtration is preferably 0.07-0.09MPa, further preferably 0.08MPa, the temperature of the drying is preferably 55-65℃, further preferably 60℃, and the time of the drying is preferably 8-16h, further preferably 10-14h, more preferably 12h.

[0048] In the present application, the conductive agent is preferably carbon nanotubes, carbon black, graphite, graphene or reduced graphene oxide;

[0049] The binder solution is preferably one or two of a polyvinylidene fluoride solution, a polytetrafluoroethylene solution and an alkaline ionomer solution; the mass fraction of the alkaline ionomer solution is preferably 5-20%, further preferably 8-16%, more preferably 10-15%, and the mass fraction of the polytetrafluoroethylene solution and the polyvinylidene fluoride solution is independently preferably 10-60%, further preferably 20-50%, more preferably 30-40%;

[0050] The mass fraction of the surfactant solution is preferably 5-30%, further preferably 10-25%, more preferably 15-20%, and the surfactant is preferably one or two of polyvinyl alcohol, polyvinylpyrrolidone, sodium dodecyl sulfonate, fatty alcohol polyoxyethylene ether and polyethylene glycol;

[0051] The mass fraction of the scale inhibitor solution is preferably 5-50%, further preferably 10-45%, more preferably 15-40%, and the scale inhibitor is preferably sodium polyphosphate, organic phosphonate, sodium polyacrylate, polyepoxysuccinic acid, polymaleic anhydride or polyaspartic acid;

[0052] The dispersant is preferably composed of water and an organic solvent, and the organic solvent is preferably ethanol, isopropanol, methanol, glycerol, pentanediol, n-butanol or acetic acid; in the dispersant, the mass fraction of water is preferably 25-80%, further preferably 35-70%, more preferably 45-60%.

[0053] In the present application, the solvent of the binder solution is pure water, the solvent of the surfactant solution is isopropyl alcohol, and the solvent of the scale inhibitor solution is a mixture of pure water and isopropyl alcohol, and the mass ratio of pure water to isopropyl alcohol in the mixture is 2:1.

[0054] In the present application, the molecular weight of polyvinyl alcohol is preferably 31000-50000.

[0055] In the present application, when the binder solution is two kinds, the mass ratio of the first binder solution to the second binder solution is preferably 1-5:1-7, further preferably 1-3:1-3; the basic ionomer in the binder solution is preferably Sustainion®XA-9, Sustainion®XB-7, Sustainion®XC-2 or Fumion FAA-3-SOLUT-10; when the surfactant solution is two kinds, the mass ratio of the first surfactant solution to the second surfactant solution is preferably 1-10:1-10, further preferably 1-9:1-9, more preferably 1-7:1-7.

[0056] In the present application, the mixing method in step 1) is preferably ultrasonic, immersion or electrophoretic adsorption; the protective atmosphere is preferably argon or nitrogen; the oxygen-containing atmosphere in step 2) is preferably high-purity oxygen, air or carbon dioxide.

[0057] In the present application, in the first calcination in step 1) and the second calcination in step 2), the calcination temperature is independently preferably 250-500℃, further preferably 300-450℃, more preferably 350-410℃, the calcination time is independently preferably 0.5-2.5h, further preferably 1-2h, more preferably 1.5h, and the heating rate to the calcination temperature is independently preferably 2-10℃ / min, further preferably 4-8℃ / min, more preferably 5-6℃ / min.

[0058] In the present application, the spraying amount of the hydrophobic agent in step 2) is preferably 0.05-1.0mg / cm 2 , further preferably 0.1-0.8mg / cm 2 , more preferably 0.4-0.6mg / cm 2 .

[0059] The present application also provides a self-breathing anti-fouling cathode prepared by the preparation method.

[0060] The present application also provides an electrolytic cell of the self-breathing anti-fouling cathode, which comprises an anode end plate 1, a hydrophobic anode 2, a first gasket 3, an electrolyte flow cavity 4, a second gasket 31, the self-breathing anti-fouling cathode 5, a hollow current collector 6, a third gasket 32, and a cathode end plate 7.

[0061] The hydrophobic anode 2 is assembled to the anode end plate 1 through the anode terminal mounting hole 11; the self-breathing anti-scaling cathode 5 quickly engages with the hollow current collector 6 and is embedded into the cathode end plate 7 through the cathode terminal mounting hole 71; the electrolyte flow chamber 4 is provided with a reaction through hole connecting the anode end plate 1 and the cathode end plate 7.

[0062] The negative end plate 7 has a hollow structure.

[0063] In this invention, the anode end plate 1 is provided with an anode terminal mounting hole 11 and an anode internal thread structure 12; the cathode end plate 7 is designed with a hollow structure to allow air to pass through, and is correspondingly configured with a cathode terminal mounting hole 71 and a cathode internal thread structure 72; the electrolyte flow chamber 4 is provided with a reaction through hole connecting the anode end plate 1 and the cathode end plate 7, and the reaction through hole continuously pumps the wastewater to be treated into the electrolyte inlet 41 through a peristaltic pump, and discharges the treated wastewater into the outlet 42; the reaction through hole is a circular opening located in the center of the electrolyte flow chamber, and the size of the circular opening is preferably 5~25cm×5~25cm, more preferably 6~20cm×6cm. The length is approximately 20 cm, more preferably 8-18 cm × 8-18 cm, and both sides are provided with external threaded interface structures 43; the electrolyte flow chamber 4 is quickly matched and connected to the cathode internal thread structure 72 on the cathode end plate 7 through the external threaded interface structure 43 via a precisely designed threaded interface structure; similarly, the electrolyte flow chamber 4 is quickly matched and connected to the anode internal thread structure 12 on the anode end plate 1 through the external threaded interface structure 43 via a precisely designed threaded interface structure; the rotation speed of the peristaltic pump is preferably 50-500 r / min, more preferably 100-400 r / min, and more preferably 200-300 r / min.

[0064] In this invention, the preferred method for preparing the hydrophobic anode is as follows:

[0065] A titanium substrate is subjected to constant current electrodeposition and a first calcination sequentially to obtain an anode electrode; the anode electrode is then coated with a hydrophobic agent and subjected to a second calcination sequentially to obtain a hydrophobic anode.

[0066] The electrolyte for constant current electrodeposition preferably comprises a metal precursor and a solvent. The metal precursor is preferably chloroiridium acid and ruthenium chloride, and the molar ratio of chloroiridium acid to ruthenium chloride is preferably 1:0.2~3, more preferably 1:0.5~2.5, and even more preferably 1:1~2. The solvent is preferably one or two of methanol, ethanol, isopropanol, and n-butanol. The concentration of the metal precursor in the electrolyte is preferably 0.1~0.5 mol / L, more preferably 0.2~0.4 mol / L, and even more preferably 0.3 mol / L.

[0067] In the present application, when the solvent in the constant current electrodeposition is any two, the volume ratio of the two solvents is preferably 1:1-5, further preferably 1:1-2, and more preferably 1:1.

[0068] In the present application, the temperature of the constant current electrodeposition is preferably 1-10℃, further preferably 3-8℃, and more preferably 5-6℃, the current density is preferably 5-50mA / cm 2 , further preferably 10-40mA / cm 2 , and more preferably 20-30mA / cm 2 , and the time is preferably 10-40min, further preferably 20-30min, and more preferably 25min.

[0069] The temperature of the first calcination is preferably 400-500℃, further preferably 420-480℃, and more preferably 450-460℃, the time is preferably 0.5-2h, further preferably 0.75-1.5h, and more preferably 1-1.25h, and the heating rate to the first calcination temperature is preferably 2-10℃ / min, further preferably 4-8℃ / min, and more preferably 5-6℃ / min; the temperature of the second calcination is preferably 250-500℃, further preferably 300-450℃, and more preferably 350-400℃, the time is preferably 0.5-2.5h, further preferably 1-2h, and more preferably 1.5h, and the heating rate to the second calcination temperature is preferably 2-10℃ / min, further preferably 4-8℃ / min, and more preferably 5-6℃ / min.

[0070] The hydrophobic agent is preferably polytetrafluoroethylene, methyltrimethoxysilane or polydimethylsiloxane, and the spraying amount of the hydrophobic agent is preferably 0.05-1.0mg / cm 2 , further preferably 0.1-0.8mg / cm 2 , and more preferably 0.4-0.6mg / cm 2 .

[0071] In the present application, the contact angle of the hydrophobic anode is preferably 130-150°, further preferably 135-145°, and more preferably 140°.

[0072] The present application also provides the use of the electrolytic cell in degrading and removing pollutants in water bodies.

[0073] The present application does not have special limitations on the method of use, and can be used according to methods well known in the art.

[0074] The technical solutions provided by the present application will be described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0075] The preparation process of the catalyst used in the examples and comparative examples is as follows: 1 g of carbon black is dispersed in 700 mL of a sodium hydroxide aqueous solution with a concentration of 6 mol / L, and hydrothermal reaction is carried out in a reaction kettle at 180 °C for 12 h. After the reaction is completed, the product is washed with ethanol (a mixture of anhydrous ethanol and deionized water with a volume ratio of 1 : 1) until the supernatant is neutral. Then, the product is suction filtered under a vacuum of 0.08 MPa. Finally, the product is dried at 60 °C for 12 h.

[0076] The basic ionomer is XC-2; the carbon substrate is SGL porous carbon fiber felt GFD 4.65 EA (thickness of 4.6 mm).

[0077] Example 1

[0078] Graphite is used as the conductive agent, a polytetrafluoroethylene solution (mass fraction of 10%) and a basic ionomer solution (mass fraction of 5%) with a mass ratio of 3: 1 are used as the binder solution, a polyvinyl alcohol solution (molecular weight of 40000) with a mass fraction of 5% is used as the surfactant solution, a polyepoxysuccinic acid solution (relative molecular mass of 1000) with a mass fraction of 20% is used as the scale inhibitor solution, and a mixture of water and isopropyl alcohol (mass fraction of water of 70%) is used as the dispersant. The catalyst, conductive agent, binder solution, surfactant solution, scale inhibitor solution and dispersant are mixed in a mass ratio of 1: 1: 0.4: 0.8: 0.6: 80. The mixture is stirred at a speed of 200 rpm for 60 min and then ball milled at a speed of 500 rpm for 4 h (the ball milling medium is agate ball milling beads) to obtain a catalyst precursor solution. The catalyst precursor solution is adsorbed onto the carbon substrate by electrophoresis. The specific process of electrophoresis adsorption is as follows: the carbon substrate is immersed in the catalyst precursor solution, a platinum mesh is used as the counter electrode and placed 2 cm away from the working electrode, the two electrodes are connected to a direct current power supply to apply a voltage of 30 V, and the time is 30 min. After completion, the obtained electrode is dried in an oven at 60 °C overnight. Then, the electrode is transferred into a nitrogen atmosphere, heated to 350 °C at a heating rate of 5 °C / min, and calcined at 350 °C for 1 h to obtain a scale-resistant cathode. Subsequently, polytetrafluoroethylene is sprayed on one side of the scale-resistant cathode, and the spraying load is 1.0 mg / cm 2 . Finally, the electrode is transferred into an air atmosphere, heated to 350 °C at a heating rate of 5 °C / min, and calcined at 350 °C for 1 h to obtain a self-breathing scale-resistant cathode.

[0079] Example 2

[0080] The carbon black was used as the conductive agent, the solution of polytetrafluoroethylene (10% by mass) and the solution of polyvinylidene fluoride (15% by mass) with a mass ratio of 1:1 were used as the binder solution, the solution of polyvinylpyrrolidone (15% by mass) was used as the surfactant solution, the solution of polyaspartic acid (15% by mass) was used as the scale inhibitor solution, the mixture of water and glycerol (50% by mass of water) was used as the dispersant; the catalyst, the conductive agent, the binder solution, the surfactant solution, the scale inhibitor solution and the dispersant were mixed with a mass ratio of 1:0.5:0.2:0.5:1.6:60, and the mixture was stirred for 60 min and then ball-milled for 4 h to obtain a catalyst precursor solution. The catalyst precursor solution was ultrasonically dispersed on a carbon substrate at a frequency of 40 kHz for 30 min at a temperature of 8 ℃. Then, the carbon substrate was transferred into a nitrogen atmosphere, and heated to 300 ℃ at a heating rate of 3 ℃ / min, and calcined at 300 ℃ for 2 h to obtain the scale-resistant cathode. Subsequently, methyltrimethoxysilane was sprayed on one side of the scale-resistant cathode, and the spraying load was 0.5 mg / cm 2 . Finally, the scale-resistant cathode was transferred into an air atmosphere, and heated to 350 ℃ at a heating rate of 3 ℃ / min, and calcined at 350 ℃ for 1 h to obtain the self-breathing scale-resistant cathode.

[0081] Example 3

[0082] The graphene was used as the conductive agent, the solution of polytetrafluoroethylene (20% by mass) was used as the binder solution, the solution of sodium dodecyl sulfonate (10% by mass) was used as the surfactant solution, the solution of polymaleic anhydride (25% by mass) was used as the scale inhibitor solution, and the mixture of water and n-butanol (40% by mass of water) was used as the dispersant; the catalyst, the conductive agent, the binder solution, the surfactant solution, the scale inhibitor solution and the dispersant were mixed with a mass ratio of 1:1.5:1:1.8:0.8:70, and the mixture was stirred for 60 min and then ball-milled for 4 h to obtain a catalyst precursor solution. The catalyst precursor solution was impregnated on a carbon substrate. Then, the carbon substrate was transferred into a nitrogen atmosphere, and heated to 450 ℃ at a heating rate of 7 ℃ / min, and calcined at 450 ℃ for 0.5 h to obtain the scale-resistant cathode. Subsequently, polytetrafluoroethylene was sprayed on one side of the scale-resistant cathode, and the spraying load was 0.3 mg / cm 2 . Finally, the scale-resistant cathode was transferred into a high-purity oxygen atmosphere, and heated to 400 ℃ at a heating rate of 7 ℃ / min, and calcined at 400 ℃ for 0.5 h to obtain the self-breathing scale-resistant cathode.

[0083] Comparative Example 1

[0084] The carbon nanotube was used as the conductive agent, the polytetrafluoroethylene solution with a mass fraction of 10% was used as the binder solution, the polyethylene glycol (molecular weight of 400) solution with a mass fraction of 20% was used as the surfactant solution, and the mixture of water and isopropyl alcohol (mass fraction of water of 70%) was used as the dispersant; the catalyst, the conductive agent, the binder solution, the surfactant solution and the dispersant were mixed in a mass ratio of 1:1:0.25:0.8:80, the mixture was stirred for 60 min and then ball-milled for 4 h to obtain a catalyst precursor solution. The catalyst precursor solution was impregnated on a carbon substrate. Subsequently, the carbon substrate was transferred into a nitrogen atmosphere, and was heated to 410 ℃ at a heating rate of 5 ℃ / min, and was calcined at 410 ℃ for 1 h to obtain a scale-resistant cathode. Subsequently, polytetrafluoroethylene was sprayed on one side of the scale-resistant cathode, and the spraying load was 0.8 mg / cm 2 . Finally, the scale-resistant cathode was transferred into an air atmosphere, and was heated to 350 ℃ at a heating rate of 5 ℃ / min, and was calcined at 350 ℃ for 1 h to obtain a self-breathing scale-resistant cathode.

[0085] Comparative Example 2

[0086] The reduced graphene oxide was used as the conductive agent, the polytetrafluoroethylene solution (mass fraction of 10%) and the naphthalene perfluorosulfonic acid solution (mass fraction of 5%) in a mass ratio of 1:1 were used as the binder solution, the fatty alcohol polyoxyethylene ether (relative molecular mass of 315) solution with a mass fraction of 10% was used as the surfactant solution, and the mixture of water and isopropyl alcohol (mass fraction of water of 60%) was used as the dispersant; the catalyst, the conductive agent, the binder solution, the surfactant solution and the dispersant were mixed in a mass ratio of 1:1:0.5:0.6:70, the mixture was stirred for 60 min and then ball-milled for 4 h to obtain a catalyst precursor solution. The catalyst precursor solution was ultrasonically treated on a carbon substrate. Subsequently, the carbon substrate was transferred into a nitrogen atmosphere, and was heated to 250 ℃ at a heating rate of 5 ℃ / min, and was calcined at 250 ℃ for 1 h to obtain a scale-resistant cathode. Subsequently, polytetrafluoroethylene was sprayed on one side of the scale-resistant cathode, and the spraying load was 0.75 mg / cm 2 . Finally, the scale-resistant cathode was transferred into an air atmosphere, and was heated to 350 ℃ at a heating rate of 5 ℃ / min, and was calcined at 350 ℃ for 1 h to obtain a self-breathing scale-resistant cathode.

[0087] The linear sweep voltammetry curves of the self-breathing scale-resistant cathodes prepared in Example 1 and Comparative Examples 1-2 under different conditions are shown in Figure 1 , and the linear sweep voltammetry curves were obtained by electrochemical performance testing in an H-type cell and a 0.1M Na2SO4 solution; it can be known from Figure 1 that the limiting current density is Example 1 ≈ Comparative Example 1 > Comparative Example 2.

[0088] Although the adsorption of scale inhibitor molecules on the catalyst surface may cover some reactive sites, dual activity compensation is achieved through the synergistic design of multiple binders: on the one hand, the Sustainion® XC-2 alkaline ionomer achieves OH... - The high efficiency of conduction facilitates the exposure of the catalytic interface that is obscured by the scale inhibitor; on the other hand, the polytetrafluoroethylene (PTFE) constructs a through-hole porous framework, which endows the electrode with excellent mechanical strength while improving the oxygen mass transfer rate, thus exhibiting a limiting current density of Example 1 ≈ Comparative Example 1. Compared with perfluorosulfonyl naphthol, the basic ionomer of Sustainion® XC-2 is more conducive to the two-electron oxygen reduction reaction.

[0089] The hydrogen peroxide generation (a), Faraday efficiency (b), and scale accumulation (c) of the self-breathing anti-scaling cathodes prepared under different conditions in Examples 1 and 1-2 are as follows: Figure 2 As shown, the reaction occurred in 100 mL of tap water with a conductivity of 900 μS / cm at a rate of 10 mA / cm. 2 The current density was operated for 30 minutes.

[0090] from Figure 2 As shown in Part a, the hydrogen peroxide production in Example 1 was 20.6227 mg / L, which was higher than that in Comparative Example 1 (14.2425 mg / L) and Comparative Example 2 (11.5607 mg / L). After 150 hours of testing, the hydrogen peroxide production in Example 1 was 17.9818 mg / L, which was higher than that in Comparative Example 1 (5.5773 mg / L) and Comparative Example 2 (1.8136 mg / L), indicating that Example 1 has excellent ORR activity and stability in tap water.

[0091] from Figure 2 As shown in Part b, the Faraday efficiency of Example 1 was 65.03%, higher than that of Comparative Example 1 (44.91%) and Comparative Example 2 (36.45%). After 150 hours of testing, the Faraday efficiency was 56.70%, higher than that of Comparative Example 1 (17.59%) and Comparative Example 2 (5.72%), indicating that Example 1 has excellent ORR activity and selectivity in tap water. This is because Example 1 used the binder Sustainion® XC-2 basic ionomer in a Ca-containing environment. 2+ / Mg 2+ In water treatment scenarios involving divalent ions, the electrostatic repulsion mechanism of their quaternary ammonium groups blocks Ca2+. 2+ / Mg 2+ The proximity of the alkaline ionomers, which primarily conduct hydroxyl radicals, facilitates the formation of a locally high-pH alkaline environment, leading to increased surface CO32- concentration. 2- / OH - An increased proportion accelerates CO3 2-Hydrolysis occurs, forming soluble Ca(HCO3)2 instead of CaCO3 precipitate, thus reducing the risk of scaling. Furthermore, the localized alkaline environment favors the two-electron oxygen reduction reaction, resulting in higher hydrogen peroxide production and Faraday efficiency. In Comparative Example 2, when perfluorosulfonyl naphthol is used, its sulfonate groups readily electrostatically adsorb Ca... 2+ / Mg 2+ The formation of sulfonate precipitates, and the fact that perfluorosulfonate naphthol mainly conducts hydrogen ions, makes the surface of the cathode electrode locally acidic, which is not conducive to the two-electron oxygen reduction reaction, thus resulting in poor hydrogen peroxide production and Faraday efficiency.

[0092] from Figure 2 As shown in section c, after 150 hours of operation, the amount of scale on the surface of Example 1 was 0.3702g, which was significantly lower than that of Comparative Example 1 (0.9826g) and Comparative Example 2 (1.1274g), indicating that the introduction of scale inhibitor can further reduce the amount of scale and extend the service life of the cathode electrode.

[0093] Application Example 1

[0094] like Figure 3 As shown, the electrolytic cell consists of an anode end plate 1, a hydrophobic anode 2, a first gasket 3, an electrolyte flow chamber 4, a second gasket 31, a self-breathing anti-scaling cathode 5 (as described in Example 1), a perforated current collector 6, a third gasket 32, and a cathode end plate 7. The anode end plate 1 has an anode terminal mounting hole 11 and an anode internal thread structure 12; the hydrophobic anode 2 is assembled to the anode end plate 1 through the anode terminal mounting hole 11; the cathode end plate 7 adopts a perforated structure design to allow air to pass through, and is correspondingly equipped with a cathode terminal mounting hole 71 and a cathode internal thread structure 72. In Example 1, the self-breathing anti-scaling cathode 5 and the perforated current collector 6 quickly engage and are embedded into the cathode end plate 7 through the cathode terminal mounting hole 71. The electrolyte flow chamber 4 is provided with a reaction through hole connecting the anode end plate 1 and the cathode end plate 7. The reaction through hole continuously pumps wastewater (containing trichloroacetaldehyde, with an initial concentration of 15 mg / L) into the electrolyte inlet 41 through a peristaltic pump (speed of 200 r / min), and discharges the treated wastewater through the outlet 42. The reaction through hole is a circular opening located in the center of the electrolyte flow chamber, with a size of 5 cm × 5 cm, and external thread interface structures 43 are provided on both the left and right sides. The electrolyte flow chamber 4 is quickly matched and connected to the cathode internal thread structure 72 on the cathode end plate 7 through the external thread interface structure 43 via a precisely designed thread interface structure. Similarly, the electrolyte flow chamber 4 is quickly matched and connected to the anode internal thread structure 12 on the anode end plate 1 through the external thread interface structure 43 via a precisely designed thread interface structure.

[0095] Preparation of the hydrophobic anode 2: the metal precursor is chloroiridic acid and ruthenium chloride with a molar ratio of 1:2, and the solvent is anhydrous ethanol and n-butanol with a volume ratio of 1:1. The metal precursor and the solvent are mixed uniformly to obtain an electrolyte with a metal precursor concentration of 0.2 mol / L. Then the electrolyte is uniformly grown on a titanium substrate material under the constant current electrodeposition conditions of a temperature of 4℃ and a current density of 30 mA / cm 2 . After electrodeposition, it is dried in an oven and transferred to a muffle furnace for calcination. The temperature is raised to 450℃ at a rate of 5℃ / min, and calcination is carried out at 450℃ for 1 h to obtain an anode electrode. Then, polytetrafluoroethylene is sprayed on the surface of the anode electrode, and the spraying load is 0.75 mg / cm 2 . Finally, it is transferred to an air atmosphere, the temperature is raised to 350℃ at a rate of 5℃ / min, and calcination is carried out at 350℃ for 1 h to obtain a hydrophobic anode.

[0096] Using the above electrolytic cell to remove pollutants in wastewater: the treated wastewater is introduced into the electrolyte flow cavity at a circulating flow rate of 50 mL / min. The self-breathing anti-fouling cathode and the hollow structure integrated design on the cathode end plate form a stable three-phase interface with oxygen in the air, water in the electrolyte flow cavity, and catalyst on the electrode surface, realizing efficient and stable synthesis of H2O2. The hydrophobic porous layer on the surface of the hydrophobic anode hinders the transfer of H2O2 to the anode active site, reducing the direct contact of H2O2 with the electrode, thereby inhibiting the degradation of H2O2 at the anode, and realizing efficient removal of pollutants. If the catalyst of the self-breathing anti-fouling cathode is poisoned due to long-term operation in wastewater, the cathode electrode can be quickly replaced through the threaded inner buckle interface design, ensuring the continuity of the process and reducing the operating cost.

[0097] The electrolytic cell schematic diagram using the self-breathing anti-fouling cathode prepared in Example 1 of Application Example 1 is shown in Figure 3 . As can be seen from Figure 3 , the self-breathing anti-fouling cathode 5 of Example 1 quickly engages with the hollow current collector 6, and is embedded into the cathode end plate 7 through the cathode terminal post mounting hole 71; and the electrolyte flow cavity 4 is quickly matched and connected through the precisely designed threaded interface structure through the outer threaded interface structure 43 and the cathode inner threaded structure 72 on the cathode end plate 7, thereby realizing quick replacement of the failed cathode electrode.

[0098] Application Example 2

[0099] Only the hydrophobic anode in Application Example 1 is replaced by an anode electrode, and the other conditions are the same as those in Application Example 1.

[0100] Preparation of anode electrode: the metal precursor was chloroiridic acid and ruthenium chloride with a molar ratio of 1:1, the solvent was n-butanol, the metal precursor and the solvent were mixed uniformly to obtain an electrolyte with a metal precursor concentration of 0.135 mol / L. Subsequently, the electrolyte was uniformly grown on a titanium substrate material under the constant current electrodeposition conditions of a temperature of 4℃ and a current density of 35 mA / cm 2 2. The anode electrode was placed in an oven for drying and was transferred into a muffle furnace for calcination treatment, the temperature was increased to 400℃ at a rate of 5℃ / min, and the calcination was performed at 400℃ for 1.5 h to obtain the anode electrode.

[0101] Examples 1-2 The self-breathing anti-fouling cathode prepared in Example 1 was used in the electrolytic cell in combination with different anode electrodes, and the relationship curves of hydrogen peroxide generation amount (a), Faraday efficiency (b) and pollutant removal (c) after reaction in 0.1 M Na2SO4 aqueous solution under a current density of 100 mA / cm 2 2 were as shown in Figure 1. As can be seen from part a of Figure 1, the hydrophobic anode used in Example 1 continuously electrolyzed for 10 min, the H2O2 accumulation amount reached 412.61 mg / L, and further increased to 1180.13 mg / L after 30 min, which significantly improved the H2O2 accumulation amount compared with the unmodified anode electrode used in Example 2. The unmodified anode electrode used in Example 2 continuously electrolyzed for 10 min, the H2O2 accumulation amount reached 280.55 mg / L, and was 447.31 mg / L after 30 min. Figure 4 Figure 4 As can be seen from part b of Figure 1, the Faraday efficiency of the hydrophobic anode used in Example 1 was 86.73% after 10 min of continuous electrolysis, and the Faraday efficiency was 82.69% after 30 min; the Faraday efficiency of the unmodified anode electrode used in Example 2 was 58.97% after 10 min of continuous electrolysis, and the Faraday efficiency was 33.44% after 30 min, indicating that coating a hydrophobic porous layer on the anode electrode effectively reduced the contact of H2O2 with the electrode surface, thereby reducing the direct degradation of H2O2 at the anode.

[0102] As can be seen from part c of Figure 1, the removal rate of the pollutant trichloroacetaldehyde by the hydrophobic anode used in Example 1 was 76.2% at 10 min, which was significantly higher than that of the unmodified anode electrode used in Example 2 (55.70%), indicating that the higher the H2O2 accumulation amount in Example 1 compared with Example 2, the faster the pollutant degradation rate. Figure 4

[0103] As can be seen from part c of Figure 1, the removal rate of the pollutant trichloroacetaldehyde by the hydrophobic anode used in Example 1 was 76.2% at 10 min, which was significantly higher than that of the unmodified anode electrode used in Example 2 (55.70%), indicating that the higher the H2O2 accumulation amount in Example 1 compared with Example 2, the faster the pollutant degradation rate. Figure 4

[0104] ​​​The self-breathing anti-fouling cathode improves the utilization efficiency of oxygen by self-breathing without oxygen exposure, thereby reducing energy consumption. , Mg and other divalent metal ions on the electrode surface, significantly reducing the risk of fouling, improving the efficiency of hydrogen peroxide generation and the service life of the electrode; at the same time, the self-breathing has a spatial hydrophobic microenvironment, greatly improving the mass transfer efficiency of oxygen from the gas phase to the catalytically active site, and the synergistic effect of the two greatly improves the hydrogen peroxide generation rate. The electrolytic cell of the present application introduces an innovative hydrophobic anode design in addition to the self-breathing anti-fouling cathode described above, which can reduce the decomposition of hydrogen peroxide caused by direct oxidation of the anode, thereby more effectively reducing the consumption of hydrogen peroxide. In addition, the cathode electrode realizes quick replacement of the cathode electrode through a threaded inner buckle type interface design, solving the problem of catalyst poisoning during long-term operation, and ultimately achieving rapid decomposition of pollutants.

[0105] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method for preparing a self-breathing anti-fouling cathode, characterized by, The method comprises the following steps: 1) mixing a carbon substrate and a catalyst precursor solution, and performing first calcination on the mixture under a protective atmosphere to obtain an anti-fouling cathode; 2) performing second calcination on the anti-fouling cathode after spraying a hydrophobic agent thereon under an oxygen-containing atmosphere to obtain a self-breathing anti-fouling cathode; In step 1), the catalyst precursor solution is composed of a catalyst, a conductive agent, a binder solution, a surfactant solution, a scale inhibitor solution and a dispersant, and the mass ratio of the catalyst, the conductive agent, the binder solution, the surfactant solution, the scale inhibitor solution and the dispersant is 1:0.25-2:0.1-1.25:0.1-2.4:0.2-2:10-100; The binder solution is one or two of a polyvinylidene fluoride solution, a polytetrafluoroethylene solution and a basic ionomer solution; the scale inhibitor is polyphosphate sodium, an organic phosphonate, polyacrylic acid sodium, polyepoxysuccinic acid, polymaleic anhydride or polyaspartic acid; Step 2) the hydrophobic agent is polytetrafluoroethylene, methyltrimethoxysilane or polydimethylsiloxane, and the spraying amount of the hydrophobic agent is 0.05 to 1.0 mg / cm 2 .

2. The method of claim 1, wherein the self-breathing anti-fouling cathode is prepared by the steps of: The preparation method of the catalyst comprises dispersing carbon black in a sodium hydroxide solution and performing hydrothermal reaction; The mass-to-volume ratio of the carbon black and the sodium hydroxide solution is 1g:600-900mL, and the concentration of the sodium hydroxide solution is 0.1-12mol / L; the temperature of the hydrothermal reaction is 150-200℃, and the time of the hydrothermal reaction is 6-18h.

3. The method of claim 1 or 2, wherein the self-breathing anti-fouling cathode is prepared by the steps of: The conductive agent is carbon nanotube, carbon black, graphite, graphene or reduced graphene oxide; The mass fraction of the basic ionomer solution is 5-20%, and the mass fraction of the polytetrafluoroethylene solution and the polyvinylidene fluoride solution is independently 10-60%; The mass fraction of the surfactant solution is 5-30%, and the surfactant is one or two of polyvinyl alcohol, polyvinylpyrrolidone, sodium dodecyl sulfonate, fatty alcohol polyoxyethylene ether and polyethylene glycol; The mass fraction of the scale inhibitor solution is 5-50%; The dispersant is composed of water and an organic solvent, and the organic solvent is ethanol, isopropyl alcohol, methanol, glycerol, pentanediol, n-butanol or acetic acid; in the dispersant, the mass fraction of water is 25-80%.

4. The method of claim 3, wherein the self-breathing anti-fouling cathode is prepared by the steps of: In step 1), the mixing mode is ultrasonic, immersion or electrophoretic adsorption; the protective atmosphere is argon or nitrogen; in step 2), the oxygen-containing atmosphere is high-purity oxygen, air or carbon dioxide.

5. The method of claim 4, wherein the self-breathing anti-fouling cathode is prepared by the steps of: In step 1), the first calcination and in step 2), the second calcination, the temperature of the calcination is independently 250-500℃, the time of the calcination is independently 0.5-2.5h, and the heating rate to the calcination temperature is independently 2-10℃ / min.

6. The self-breathing anti-fouling cathode prepared by the method of any one of claims 1 to 5, characterized in that, The self-breathing anti-fouling cathode does not need additional oxygen exposure.

7. An electrolytic cell comprising the self-breathing anti-fouling cathode of claim 6, characterized in that, The electrolytic cell comprises an anode end plate (1), a hydrophobic anode (2), an electrolyte flow cavity (4), a self-breathing anti-fouling cathode (5), a hollow current collector (6) and a cathode end plate (7); The hydrophobic anode (2) is assembled to the anode end plate (1) through an anode terminal mounting hole (11); The self-breathing anti-fouling cathode (5) is quickly engaged with the hollow current collector (6), and is embedded into the cathode end plate (7) through a cathode terminal mounting hole (71); the electrolyte flow cavity (4) is provided with a reaction through hole communicating the anode end plate (1) and the cathode end plate (7); The cathode end plate (7) is of a hollow structure.

8. The electrolytic cell of claim 7, wherein, The preparation method of the hydrophobic anode is: The titanium substrate is sequentially subjected to constant current electrodeposition and first calcination to obtain an anode electrode; the anode electrode is sequentially sprayed with a hydrophobic agent and subjected to second calcination to obtain the hydrophobic anode; The electrolyte for the constant current electrodeposition comprises a metal precursor and a solvent, the metal precursor is chloroiridic acid and ruthenium chloride, the molar ratio of the chloroiridic acid and the ruthenium chloride is 1:0.2-3; the solvent is one or two of methanol, ethanol, isopropanol and n-butanol; in the electrolyte, the concentration of the metal precursor is 0.1-0.5 mol / L.

9. The electrolytic cell of claim 8, wherein, The temperature of the constant current electrodeposition is 1-10 ℃, the current density is 5-50 mA / cm 2 , and the time is 10-40 min. The temperature of the first calcination is 400-500 DEG C, the time is 0.5-2 h, the temperature rising rate to the first calcination temperature is 2-10 DEG C / min; the temperature of the second calcination is 250-500 DEG C, the time is 0.5-2.5 h, the temperature rising rate to the second calcination temperature is 2-10 DEG C / min; The hydrophobic agent is polytetrafluoroethylene, methyltrimethoxysilane or polydimethylsiloxane, and the spraying amount of the hydrophobic agent is 0.05-1.0 mg / cm 2 .

10. Use of the electrolytic cell according to any one of claims 7-9 in degrading and removing pollutants in a water body.

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