An oxygen capturing cathode and its preparation method and application

Abstract

The application provides an oxygen capturing cathode and a preparation method and application thereof, and belongs to the technical field of environmental functional materials. The oxygen capturing cathode comprises a carbon paper electrode substrate, wherein the carbon paper electrode substrate is sequentially loaded with a gas attracting layer and a catalytic layer from top to bottom, and the catalytic layer raw material comprises carbon black, and the gas attracting layer raw material comprises polyvinylidene fluoride. The oxygen capturing cathode is simple to prepare, and an electrochemical system based on the oxygen capturing cathode can efficiently degrade / mineralize organic wastewater, and has strong adaptability to the concentration range of the organic wastewater, and can be used for deep treatment of low-concentration wastewater and pretreatment of higher-concentration wastewater.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials technology, and particularly relates to an oxygen capture cathode, its preparation method and application. Background Technology

[0002] Utilizing renewable electricity to drive the reduction of O2 into the environmentally friendly oxidant H2O2 is an important option for constructing green and efficient oxidation systems. This is also gradually becoming an effective means of addressing recalcitrant pollutants, especially emerging ones. The basic principle of this technology is that O2 is first adsorbed onto the catalyst surface to form adsorbed *O2, which undergoes electron-proton co-transfer to generate *OOH. A second step of electron-proton co-transfer then generates *HOOH, which is finally desorbed to generate H2O2 (Equations 1 and 2). The generated H2O2 in solution possesses strong oxidizing power, enabling in-situ degradation of pollutants, and offers advantages such as rapid reaction rate and high pollutant mineralization rate.

[0003] O2+H + +e - →*OOH (1)

[0004] *OOH+H + +e - →HOOH (2)

[0005] In the ORR process, each step—from the mass transfer of O2 dissolving to the electrode surface, the chemisorption of O2 molecules at the catalytic site, the first electron transfer of O2 molecules, to the final formation of H2O2—could be rate-limiting steps. Currently, efforts to enhance the ORR process mainly focus on regulating the cathode catalytic site, while the mass transfer process of O2 molecules has not received sufficient attention. According to Equation 1, O2, as an important precursor for H2O2 synthesis, plays a crucial role in enhancing the diffusion of gaseous O2 to the catalytic layer and providing sufficient reactants (O2) to the cathode surface, thus significantly improving the efficiency of H2O2 electrosynthesis.

[0006] Current patent reports on enhancing O2 diffusion into the catalyst layer mainly focus on reactor design and cathode aeration configuration. These methods typically involve controlling the gas pressure or turbulence state of the solution, using designs such as gas diffusion and rotating cylindrical electrodes. These pressurize the system and generate turbulence, thereby improving O2 mass transfer. However, these methods suffer from problems such as increased energy consumption and high costs. Summary of the Invention

[0007] To address the problem of high diffusion resistance of gaseous O2 into the catalyst layer in the existing electron electrosynthesis of H2O2, which leads to insufficient O2 concentration and reduced H2O2 current efficiency, this invention proposes an oxygen capture cathode, its preparation method, and its application.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] One of the technical solutions of the present invention:

[0010] An oxygen capture cathode includes a carbon paper electrode substrate, wherein a gas attraction layer and a catalyst layer are loaded sequentially from top to bottom on the carbon paper electrode substrate, the catalyst layer being made of carbon black and the gas attraction layer being made of polyvinylidene fluoride.

[0011] The gas attraction layer material of this invention contains polyvinylidene fluoride (PVDF). The addition of PVDF enhances the hydrophobicity of the gas attraction layer, thereby enabling the oxygen capture cathode to improve the attraction of bubbles in the liquid phase and achieve rapid capture of oxygen bubbles in the liquid phase. There is an interfacial interaction (physical adsorption or weak chemical bond) between the carbon black particles in the catalyst layer material and PVDF. This interaction can achieve the capture of oxygen bubbles, enhance the diffusion of oxygen bubbles to the electrode surface, and facilitate the electrosynthesis of H2O2. As a result, the electrochemical system based on the oxygen capture cathode has an ideal removal effect on the treatment of sulfathiazole antibiotics.

[0012] Preferably, the carbon black particles have a particle size of 30 nm.

[0013] Preferably, the thickness of the gas attraction layer is 0.39 μm; and the thickness of the catalyst layer is 0.86-1.14 μm.

[0014] This invention further regulates the roughness of the catalyst layer by adjusting the particle size of carbon black particles, and combines this with the adjustment of the thickness of the gas attraction layer to achieve the regulation of the interaction force between the oxygen capture cathode and the oxygen bubbles.

[0015] The second technical solution of the present invention:

[0016] A method for preparing an oxygen capture cathode includes the following steps:

[0017] (1) Cut carbon paper into electrode sheets, wash and dry them to obtain carbon paper electrode substrates;

[0018] (2) Coating the carbon black solution onto the carbon paper electrode substrate and drying it to obtain a carbon paper electrode substrate loaded with carbon black.

[0019] (3) Coat the side of the carbon paper electrode substrate loaded with carbon black with polyvinylidene fluoride solution and dry it to obtain the oxygen capture cathode.

[0020] Furthermore, the carbon paper is cut into electrode pieces of (1-5)cm × (2-10)cm.

[0021] Further, in step (1), the carbon paper is cut into electrode sheets, ultrasonically cleaned with acetone or ethanol to remove surface organic matter, rinsed with deionized water and dried at 60-80°C to obtain a clean carbon paper electrode substrate.

[0022] Further, the carbon black solution is an ethanol solution of carbon black, and the concentration of carbon black in the carbon black solution is (0.036~0.06) g / (6~10) mL.

[0023] Furthermore, the amount of carbon black solution coated on the carbon paper electrode substrate is 100–300 μL.

[0024] Furthermore, in step (2), the drying temperature is 60-80°C and the drying time is 8-10 hours.

[0025] Furthermore, the polyvinylidene fluoride solution is an N,N-dimethylformamide solution of polyvinylidene fluoride, and the concentration of polyvinylidene fluoride in the polyvinylidene fluoride solution is (0.036~0.06) g / (6~10) mL.

[0026] Furthermore, the amount of polyvinylidene fluoride solution coated on the carbon paper electrode substrate is 100–300 μL.

[0027] Furthermore, in step (3), the drying temperature is 60-80°C and the drying time is 8-10 hours.

[0028] The third technical solution of the present invention:

[0029] The application of the oxygen capture cathode in the electrochemical treatment of wastewater.

[0030] Furthermore, the oxygen capture cathode and anode form an electrode pair, which is connected to a DC power supply and inserted into the organic wastewater. The pH value of the organic wastewater is adjusted to 2-6, oxygen is introduced into the wastewater, and an electrochemical reaction is carried out to complete the treatment of the organic wastewater. The anode is a boron-doped diamond anode, a titanium suboxide anode, or a platinum electrode.

[0031] Compared with the prior art, the present invention has the following advantages and technical effects:

[0032] (1) This invention employs a simple physical deposition method to construct an oxygen capture cathode with a catalyst layer and a gas attraction layer. By varying the carbon black concentration (0.036–0.06 g / 6–10 mL) to achieve different carbon black loading amounts (100–300 μL), different thicknesses of catalyst layers are obtained to control the roughness of the catalyst layer. Combined with limiting the thickness of the gas attraction layer, this allows for the control of the interaction force between the oxygen capture cathode and the oxygen bubbles, resulting in a larger interaction force F between the oxygen capture cathode and the oxygen bubbles. max(275μN) has the ability to actively capture oxygen bubbles, thereby reducing the steric hindrance of oxygen mass transfer and enhancing the local oxygen concentration on the electrode surface without affecting the electronic ORR selectivity, which is conducive to the generation of H2O2.

[0033] (2) The oxygen capture cathode of the present invention is simple to prepare, flexible and scalable. The electrochemical system based on the oxygen capture cathode of the present invention can efficiently degrade / mineralize organic wastewater, and is highly adaptable to the concentration range of organic wastewater. It can be used for the deep treatment of low-concentration wastewater as well as the pretreatment of high-concentration wastewater. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1 A comparison image of the clean carbon paper electrode substrate in Comparative Example 1 and the oxygen capture cathode prepared in Example 1.

[0036] Figure 2 A scanning electron microscope image of the clean carbon paper electrode substrate in Comparative Example 1;

[0037] Figure 3 This is a scanning electron microscope cross-sectional image of the oxygen trapping cathode prepared in Example 1;

[0038] Figure 4 This is a scanning electron microscope (SEM) image of the oxygen trapping cathode prepared in Example 1.

[0039] Figure 5 The image shows the micro-area energy spectrum (F) of the oxygen capture cathode in Example 1.

[0040] Figure 6 The micro-area energy spectrum (C) of the oxygen capture cathode in Example 1;

[0041] Figure 7 The infrared spectra of the oxygen capture cathode (CB / PVDF) prepared in Example 1 and the oxygen capture cathode (CB) without polyvinylidene fluoride modification in Comparative Example 2 are compared.

[0042] Figure 8 Static contact angle diagrams of the clean carbon paper electrode substrate in Comparative Example 1 and the oxygen capture cathode prepared in Example 1;

[0043] Figure 9 The image shows the underwater oxygen bubble capture of the clean carbon paper electrode substrate in Comparative Example 1 and the oxygen capture cathode prepared in Example 1.

[0044] Figure 10The graphs show the interaction forces between the clean carbon paper electrode substrate in Comparative Example 1 and the oxygen trapping cathode prepared in Example 1 and the surface of the oxygen bubble.

[0045] Figure 11 A comparison chart showing the H2O2 accumulation of the clean carbon paper electrode substrate in Comparative Example 1 and the oxygen capture cathode prepared in Example 1;

[0046] Figure 12 The graph shows the removal efficiency of STZ and TOC by the oxygen capture cathode prepared in Example 1.

[0047] Figure 13 The graph shows the H2O2 accumulation amount of the oxygen capture cathode prepared in Example 2;

[0048] Figure 14 The graph shows the removal efficiency of the oxygen capture cathode prepared in Example 2 for STZ and TOC.

[0049] Figure 15 The graph shows the H2O2 accumulation in the oxygen capture cathode prepared in Example 3.

[0050] Figure 16 The graph shows the removal efficiency of STZ and TOC by the oxygen capture cathode prepared in Example 3. Detailed Implementation

[0051] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0052] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0053] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0054] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0055] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0056] The dimensions and thickness of the catalytic layer and gas attraction layer of the oxygen capture cathode of this invention can be customized according to application specifications, highlighting the flexibility and scalability of this invention.

[0057] This invention provides an oxygen capture cathode comprising a carbon paper electrode substrate, wherein a gas attraction layer and a catalyst layer are loaded sequentially from top to bottom on the carbon paper electrode substrate, the catalyst layer being made of carbon black and the gas attraction layer being made of polyvinylidene fluoride.

[0058] In a preferred embodiment of the present invention, the carbon black particles used are purchased from Cabot Corporation of the United States, and their particle size is 30 nm.

[0059] In a preferred embodiment of the present invention, the thickness of the gas attraction layer is 0.39 μm; the thickness of the catalyst layer is 0.86-1.14 μm.

[0060] This invention also proposes a method for preparing an oxygen capture cathode, comprising the following steps:

[0061] (1) Cut carbon paper into electrode sheets, wash and dry them to obtain carbon paper electrode substrates;

[0062] (2) Coating the carbon black solution onto the carbon paper electrode substrate and drying it to obtain a carbon paper electrode substrate loaded with carbon black.

[0063] (3) Coat the side of the carbon paper electrode substrate loaded with carbon black with polyvinylidene fluoride solution and dry it to obtain the oxygen capture cathode.

[0064] In a preferred embodiment of the present invention, carbon paper is cut into electrode sheets of (1-5)cm × (2-10)cm.

[0065] In step (1) of the preferred embodiment of the present invention, carbon paper is cut into electrode sheets, ultrasonically cleaned with acetone or ethanol to remove surface organic matter, rinsed with deionized water and dried at 60-80°C to obtain a clean carbon paper electrode substrate.

[0066] In a preferred embodiment of the present invention, the carbon black solution is an ethanol solution of carbon black, and the concentration of carbon black in the carbon black solution is (0.036~0.06) g / (6~10) mL.

[0067] In a preferred embodiment of the present invention, the amount of carbon black solution coated on the carbon paper electrode substrate is 100-300 μL.

[0068] In step (2) of the preferred embodiment of the present invention, the drying temperature is 60-80°C and the drying time is 8-10 hours.

[0069] In a preferred embodiment of the present invention, the polyvinylidene fluoride solution is an N,N-dimethylformamide solution of polyvinylidene fluoride, and the concentration of polyvinylidene fluoride in the polyvinylidene fluoride solution is (0.036~0.06) g / (6~10) mL.

[0070] In a preferred embodiment of the present invention, the amount of polyvinylidene fluoride solution coated on the carbon paper electrode substrate is 100-300 μL.

[0071] In step (3) of the preferred embodiment of the present invention, the drying temperature is 60-80°C and the drying time is 8-10 hours.

[0072] This invention also proposes the application of the oxygen capture cathode in the electrochemical treatment of wastewater.

[0073] In a preferred embodiment of the present invention, the oxygen capture cathode and anode form an electrode pair, which is connected to a DC power supply and inserted into the organic wastewater. The pH value of the organic wastewater is adjusted to 2-6, oxygen is introduced into the wastewater, and an electrochemical reaction is carried out to complete the treatment of the organic wastewater. The anode is a boron-doped diamond anode, a titanium suboxide anode, or a platinum electrode.

[0074] All raw materials used in the embodiments of the present invention are commercially available, and the coating, ultrasonic and other processes involved in the preparation are conventional techniques in the field.

[0075] The technical solution of the present invention will be further illustrated by the following embodiments.

[0076] Example 1

[0077] A method for preparing an oxygen capture cathode includes the following steps:

[0078] (1) Cut carbon paper into 1cm×2cm electrode sheets, use acetone or ethanol for ultrasonic cleaning to remove surface organic matter, rinse with deionized water and dry at 60°C to obtain a clean carbon paper electrode substrate.

[0079] (2) Dissolve 0.036g of carbon black in 6mL of ethanol solution and sonicate for 30min to obtain a uniformly dispersed carbon black solution. Coat 100μL of the prepared carbon black solution onto a clean carbon paper electrode substrate and dry it at 60℃ for 8h to obtain a carbon paper electrode substrate loaded with carbon black. A catalyst layer is prepared on the carbon paper electrode substrate.

[0080] (3) Dissolve 0.036 g of polyvinylidene fluoride in 6 mL of N,N-dimethylformamide solution and sonicate for 20 min to obtain a uniformly dispersed polyvinylidene fluoride solution. Coat 100 μL of the prepared polyvinylidene fluoride solution onto one side of a carbon paper electrode substrate loaded with carbon black and dry it at 60 °C for 8 h to obtain a carbon paper electrode substrate loaded with carbon black and polyvinylidene fluoride. A gas attraction layer is prepared on the carbon paper electrode substrate loaded with the catalyst layer, which is the oxygen capture cathode, denoted as CB / PVDF.

[0081] Comparative Example 1

[0082] Carbon paper is cut into 1cm×2cm electrode sheets, ultrasonically cleaned with acetone or ethanol to remove surface organic matter, rinsed with deionized water and dried at 60℃ to obtain a clean carbon paper electrode substrate, which is used as an oxygen capture cathode.

[0083] Comparative Example 2

[0084] (1) Cut carbon paper into 1cm×2cm electrode sheets, use acetone or ethanol for ultrasonic cleaning to remove surface organic matter, rinse with deionized water and dry at 60°C to obtain a clean carbon paper electrode substrate.

[0085] (2) Dissolve 0.036g of carbon black in 6mL of ethanol solution and sonicate for 30min to obtain a uniformly dispersed carbon black solution. Coat 100μL of the prepared carbon black solution onto a clean carbon paper electrode substrate and dry it at 60℃ for 8h to obtain a carbon paper electrode substrate loaded with carbon black. A catalyst layer is prepared on the carbon paper electrode substrate, which is the oxygen capture cathode, denoted as CB.

[0086] A comparison image of the clean carbon paper electrode substrate in Comparative Example 1 and the oxygen capture cathode prepared in Example 1 is shown below. Figure 1 The scanning electron microscope image of the clean carbon paper electrode substrate in Comparative Example 1 is shown below. Figure 2 It can be seen that the original carbon paper electrode substrate has a typical carbon fiber structure, which is conducive to the diffusion and mass transfer of products, electrolytes and oxygen.

[0087] The scanning electron microscope cross-sectional image of the oxygen trapping cathode prepared in Example 1 is shown below. Figure 3 ,from Figure 3As can be seen, the modified oxygen capture cathode of Example 1 exhibits a distinct gas-attracting layer (PVDF layers) and catalyst layer (CB NPs) structure. Cross-sectional images of the samples were captured using scanning electron microscopy (SEM), and the thicknesses of the gas diffusion layer and catalyst layer were precisely measured using image analysis software. Cross-sectional SEM measurements showed that the thickness of the gas-attracting layer was 0.39 μm, and the thickness of the catalyst layer was 0.86 μm.

[0088] The scanning electron microscope surface image of the oxygen trapping cathode prepared in Example 1 is shown below. Figure 4 ,from Figure 4 As can be seen, the modified oxygen capture cathode surface in Example 1 exhibits a micro-nano spherical structure. The carbon black nanoparticles in the catalyst layer were measured to have an average particle size of approximately 48.78 nm, which can effectively improve the three-phase interface (TPI) of electrogenerated H2O2. At the same time, the surface gas attraction layer has a porous structure. Therefore, the oxygen capture cathode of the present invention has low steric hindrance for gas transport, and the attracted gas directly reaches the catalyst layer, allowing active oxygen to diffuse to the catalyst interface.

[0089] The micro-area energy spectrum (F) of the oxygen capture cathode in Example 1 is shown below. Figure 5 The micro-area energy spectrum (C) of the oxygen capture cathode in Example 1 is shown in Figure 1. Figure 6 ,pass Figure 5 and Figure 6 Micro-area energy dispersive spectroscopy analysis of the surface showed that the elemental percentages of fluorine (F) and carbon (C) were 1.58% and 98.42%, respectively (see Table 1). The presence of fluorine indicates that the gas attraction layer and the catalyst layer have been successfully loaded onto the carbon paper substrate.

[0090] Table 1. Energy dispersive spectroscopy (EDS) analysis results of the oxygen capture cathode micro-region

[0091]

[0092]

[0093] The infrared spectra of the oxygen capture cathode (CB / PVDF) prepared in Example 1 and the oxygen capture cathode (CB) without polyvinylidene fluoride modification in Comparative Example 2 are shown in the figure. Figure 7 As can be seen, the infrared spectrum of the oxygen trapping cathode (Example 1) loaded with a gas-attracting layer of polyvinylidene fluoride showed a characteristic PVDF peak at 1397.72 cm⁻¹. -1 The peak value represents the CF tensile vibration, 871.22 cm. -1 The peak value represents the symmetrical stretching of CCC. Meanwhile, at 837.56 cm... -1 The appearance of a peak at this point indicates that there is an interfacial interaction (physical adsorption or weak chemical bonding) between PVDF and carbon particles.

[0094] The static contact angles of the clean carbon paper electrode substrate in Comparative Example 1 and the oxygen trapping cathode prepared in Example 1 are shown in Figure 1. Figure 8 It can be seen that the modified oxygen capture cathode (Example 1) has significantly improved hydrophobicity compared to the unmodified cathode (Comparative Example 1), with the contact angle increasing from 97° to 145°. The improved hydrophobicity enables the oxygen capture cathode to enhance the attraction of bubbles in the liquid phase.

[0095] Underwater oxygen bubble capture images of the clean carbon paper electrode substrate in Comparative Example 1 and the oxygen capture cathode prepared in Example 1 are shown below. Figure 9 ,from Figure 9 It can be further seen that, compared with the unmodified carbon paper cathode (Comparative Example 1), the oxygen capture cathode prepared in Example 1 of the present invention can achieve rapid capture of oxygen bubbles in the liquid phase.

[0096] The interaction force curves between the clean carbon paper electrode substrate in Comparative Example 1 and the oxygen trapping cathode prepared in Example 1 and the oxygen bubble surface are shown in the figure. Figure 10 ,according to Figure 10 It can be seen that the oxygen capture cathode prepared in Example 1 has the largest interaction force with the oxygen bubble, and the maximum interaction force (F) max The force is 275 μN, which is 5 times that of the unmodified carbon paper cathode (55 μN). This force can capture oxygen bubbles, enhance the diffusion of oxygen bubbles to the electrode surface, and facilitate the electrosynthesis of H2O2.

[0097] The oxygen capture cathode from Example 1 and the clean carbon paper electrode substrate (unmodified carbon paper cathode) from Comparative Example 1 were assembled into electrode pairs with platinum anodes, respectively. The cathode and anode were connected to the positive and negative terminals of a DC power supply, respectively, and immersed in a 100 mL Na₂SO₄ electrolyte solution with pH = 3 and a concentration of 50 mM. Oxygen was introduced into the electrolyte solution at a flow rate of 2.5 mL / min, and the current density was controlled at 5 mA·cm⁻¹. -2 The H2O2 accumulation amount of the oxygen capture cathode and the unmodified carbon paper cathode was tested. A comparison of the H2O2 accumulation amount between the clean carbon paper electrode substrate in Comparative Example 1 and the oxygen capture cathode prepared in Example 1 is shown in the figure. Figure 11 It can be seen that the oxygen capture cathode in Example 1 operates at a current density of 5 mA·cm⁻¹. -2 At that time, the H2O2 production at 15, 30, 45 and 60 min was 289.61 μmol·L⁻¹, respectively. -1 497.71 μmol·L -1 651.01 μmol·L -1 757.67 μmol·L -1The H2O2 accumulation was higher than that of the clean carbon paper electrode substrate cathode (unmodified carbon paper cathode) in Comparative Example 1 at the same current density: 13.89 μmol·L⁻¹. -1 25.33 μmol·L -1 34.22 μmol·L -1 37.58 μmol·L -1 This demonstrates that the oxygen capture cathode in Example 1 can effectively capture oxygen in the electrolyte solution, which is more conducive to the accumulation of electrogenerated H2O2.

[0098] The oxygen-capturing cathode prepared in Example 1 was assembled with a titanium suboxide anode to form an electrode pair, which was then connected to the positive and negative terminals of a DC power supply. A 100 mL volume, pH 3, sulfathiazole (STZ) concentration of 50 mg·L⁻¹ was then inserted. -1 In pharmaceutical wastewater; the current density is controlled at 5 mA·cm. -2 Oxygen was dispensed at a rate of 2.5 mL / min. -1 The flow rate was introduced into the wastewater, and the removal efficiency of STZ was tested over time. The removal efficiency of total organic carbon (TOC) was tested using the same method. The resulting removal efficiency curves for STZ and TOC are shown below. Figure 12 As shown, from Figure 12 It can be seen that at a current of 5 mA·cm -2 Within 3 hours, STZ can be almost 100% removed, while TOC removal rate can reach 63.25%. This indicates that the electrochemical system based on oxygen capture cathode has an ideal removal effect on sulfathiazole antibiotic treatment.

[0099] Example 2

[0100] A method for preparing an oxygen capture cathode includes the following steps:

[0101] (1) Cut carbon paper into 2cm×5cm electrode sheets, use acetone or ethanol for ultrasonic cleaning to remove surface organic matter, rinse with deionized water and dry at 80℃ to obtain a clean carbon paper electrode substrate.

[0102] (2) Dissolve 0.06 g of carbon black in 40 mL of ethanol solution and sonicate for 30 min to obtain a uniformly dispersed carbon black solution. Coat 2000 μL of the prepared carbon black solution onto a clean carbon paper electrode substrate and dry it at 70 °C for 10 h to obtain a carbon paper electrode substrate loaded with carbon black. A catalyst layer is prepared on the carbon paper electrode substrate.

[0103] (3) Dissolve 0.036 g of polyvinylidene fluoride in 10 mL of N,N-dimethylformamide solution and sonicate for 20 min to obtain a uniformly dispersed polyvinylidene fluoride solution. Coat 3000 μL of the prepared polyvinylidene fluoride solution onto one side of a carbon paper electrode substrate loaded with carbon black and dry it at 70 °C for 10 h to obtain a carbon paper electrode substrate loaded with carbon black and polyvinylidene fluoride. A gas attraction layer is prepared on the carbon paper electrode substrate loaded with the catalyst layer, which is the oxygen capture cathode.

[0104] Tests showed that the thickness of the gas attraction layer in the oxygen capture cathode of Example 2 was 0.39 μm, and the thickness of the catalyst layer was 1.03 μm.

[0105] The oxygen-capturing cathode from Example 2 was assembled with a platinum anode to form an electrode pair. The cathode and anode were connected to the positive and negative terminals of a DC power supply, respectively. The electrode was then immersed in a 100 mL Na₂SO₄ electrolyte solution with a pH of 3 and a concentration of 50 mM. Oxygen was introduced into the electrolyte solution at a flow rate of 2.5 mL / min, and the current density was controlled at 5 mA·cm⁻¹. -2 The H2O2 accumulation of the oxygen capture cathode and the unmodified carbon paper cathode was tested. The H2O2 accumulation of the oxygen capture cathode prepared in Example 2 is shown in [reference needed]. Figure 12 The H2O2 production at 15, 30, 45, and 60 min was 21.12 mg·L⁻¹, respectively. -1 35.46 mg·L -1 45.49 mg·L -1 55.08 mg·L -1 This demonstrates that the oxygen capture cathode in Example 2 can effectively capture oxygen in the electrolyte solution, which is more conducive to the accumulation of electrogenerated H2O2.

[0106] The oxygen capture cathode prepared in Example 2 was assembled with a titanium suboxide anode to form an electrode pair, which was then connected to the positive and negative terminals of a DC power supply. A 100 mL volume, pH 3, sulfathiazole (STZ) concentration of 50 mg·L⁻¹ was then inserted. -1 In pharmaceutical wastewater; the current density is controlled at 5 mA·cm. -2 Oxygen was dispensed at a rate of 2.5 mL / min. -1 The flow rate was introduced into the wastewater, and the removal efficiency of STZ was tested over time. The removal efficiency of total organic carbon (TOC) was tested using the same method. The resulting removal efficiency curves for STZ and TOC are shown below. Figure 14 As shown, from Figure 14 It can be seen that at a current of 5 mA·cm -2 Within 2 hours, STZ can be almost 100% removed, while TOC removal rate can reach 68.45%. This indicates that the electrochemical system based on oxygen capture cathode has an ideal removal effect on sulfathiazole antibiotic treatment.

[0107] Example 3

[0108] A method for preparing an oxygen capture cathode includes the following steps:

[0109] (1) Cut carbon paper into 5cm×6cm electrode sheets, use acetone or ethanol for ultrasonic cleaning to remove surface organic matter, rinse with deionized water and dry at 70°C to obtain a clean carbon paper electrode substrate.

[0110] (2) Dissolve 0.06 g of carbon black in 20 mL of ethanol solution and sonicate for 30 min to obtain a uniformly dispersed carbon black solution. Coat 3000 μL of the prepared carbon black solution onto a clean carbon paper electrode substrate and dry it at 60 °C for 9 h to obtain a carbon paper electrode substrate loaded with carbon black. A catalyst layer is prepared on the carbon paper electrode substrate.

[0111] (3) Dissolve 0.048 g of polyvinylidene fluoride in 8 mL of N,N-dimethylformamide solution and sonicate for 20 min to obtain a uniformly dispersed polyvinylidene fluoride solution. Coat 2000 μL of the prepared polyvinylidene fluoride solution onto one side of a carbon paper electrode substrate loaded with carbon black and dry it at 60 °C for 9 h to obtain a carbon paper electrode substrate loaded with carbon black and polyvinylidene fluoride. A gas attraction layer is prepared on the carbon paper electrode substrate loaded with the catalyst layer, which is the oxygen capture cathode.

[0112] Tests showed that the thickness of the gas attraction layer in the oxygen capture cathode of Example 3 was 0.39 μm, and the thickness of the catalyst layer was 1.14 μm.

[0113] The oxygen-capturing cathode from Example 3 was assembled with a platinum anode to form an electrode pair. The cathode and anode were connected to the positive and negative terminals of a DC power supply, respectively. The electrode was then immersed in a 100 mL Na₂SO₄ electrolyte solution with a pH of 3 and a concentration of 50 mM. Oxygen was introduced into the electrolyte solution at a flow rate of 2.5 mL / min, and the current density was controlled at 5 mA·cm⁻¹. -2 The H2O2 accumulation amount of the oxygen capture cathode and the unmodified carbon paper cathode was tested. A comparison chart of H2O2 accumulation amounts of the oxygen capture cathodes prepared in Example 3 is shown below. Figure 15 It can be seen that the oxygen capture cathode in Example 1 operates at a current density of 5 mA·cm⁻¹. -2 At that time, the H2O2 production at 15, 30, 45 and 60 min was 47.95 mg·L⁻¹, respectively. -1 81.52 mg·L -1 104.60 mg·L -1 121.99 mg·L -1This demonstrates that the oxygen capture cathode in Example 3 can effectively capture oxygen in the electrolyte solution, which is more conducive to the accumulation of electrogenerated H2O2.

[0114] The oxygen-capturing cathode prepared in Example 3 was assembled with a titanium suboxide anode to form an electrode pair, which was then connected to the positive and negative terminals of a DC power supply. A 100 mL volume, pH 3, sulfathiazole (STZ) concentration of 50 mg·L⁻¹ was then inserted. -1 In pharmaceutical wastewater; the current density is controlled at 5 mA·cm. -2 Oxygen was dispensed at a rate of 2.5 mL / min. -1 The flow rate was introduced into the wastewater, and the removal efficiency of STZ was tested over time. The removal efficiency of total organic carbon (TOC) was tested using the same method. The resulting removal efficiency curves for STZ and TOC are shown below. Figure 16 As shown, from Figure 16 It can be seen that at a current of 5 mA·cm -2 Within 15 hours, STZ can be almost 100% removed, while TOC removal rate can reach 74.83%. This indicates that the electrochemical system based on oxygen capture cathode has an ideal removal effect on sulfathiazole antibiotic treatment.

[0115] In summary, this invention employs a simple physical deposition method to construct an oxygen capture cathode with a catalytic layer and a gas attraction layer. The cathode itself has the property of attracting bubbles, thereby achieving active capture of oxygen bubbles in the electrolyte solution. This invention explores the mechanism for enhancing oxygen diffusion performance and is of great significance for achieving highly selective and highly active H2O2 synthesis and efficient degradation of antibiotic wastewater.

[0116] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. The application of an oxygen capture cathode in electrochemical wastewater treatment, characterized in that, The wastewater contained antibiotics; In the electrochemical treatment of wastewater, an oxygen capture cathode and a titanium suboxide anode are assembled into an electrode pair. The oxygen capture cathode includes a carbon paper electrode substrate, on which a gas attraction layer and a catalyst layer are loaded sequentially from top to bottom. The catalyst layer is made of carbon black, and the gas attraction layer is made of polyvinylidene fluoride. The carbon black particles have a particle size of 30 nm; The thickness of the gas-attracting layer is 0.39 μm; The thickness of the catalyst layer is 0.86-1.14 μm; The method for preparing the oxygen capture cathode includes the following steps: (1) Cut carbon paper into electrode sheets, wash and dry them to obtain carbon paper electrode substrates; (2) Coating the carbon black solution onto the carbon paper electrode substrate and drying it to obtain a carbon paper electrode substrate loaded with carbon black. The drying temperature is 60-80℃ and the time is 8-10h. (3) Coating the carbon black-loaded side of the carbon paper electrode substrate with polyvinylidene fluoride solution and drying it to obtain the oxygen capture cathode. The drying temperature is 60-80℃ and the time is 8-10h.

2. The application of the oxygen capture cathode according to claim 1 in the electrochemical treatment of wastewater, characterized in that, In step (2), the amount of carbon black solution coated on the carbon paper electrode substrate is 100-300 μL.

3. The application of the oxygen capture cathode according to claim 1 in the electrochemical treatment of wastewater, characterized in that, In step (3), the polyvinylidene fluoride solution is an N,N-dimethylformamide solution of polyvinylidene fluoride, and the concentration of polyvinylidene fluoride in the polyvinylidene fluoride solution is (0.036~0.06)g / (6~10)mL.

4. The application of the oxygen capture cathode according to claim 1 in the electrochemical treatment of wastewater, characterized in that, In step (3), the amount of polyvinylidene fluoride solution coated on the carbon paper electrode substrate is 100-300 μL.

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