A trace Br-doped Co3O4 nanowire anode material, a preparation method and an electrochemical disinfection device

Abstract

The present application relates to a kind of trace Br doped Co3O4 Nanowire anode material, preparation method and electrochemical disinfection device, and preparation method includes: the pretreated nickel foam is obtained by pickling, cleaning, drying foam nickel;Soluble cobalt salt, urea, ammonium fluoride and sodium bromide are dissolved in water, mixed to obtain precursor solution, pretreated nickel foam is immersed in and hydrothermal reaction is carried out, and cobalt oxide precursor containing bromine is grown on the foam nickel base;Then calcine in oxygen-containing atmosphere, anode material is obtained.The material is doped in the lattice by replacing the lattice oxygen of Co3O4 Br, and ammonium fluoride is used as structure directing agent to induce nanowire formation.The present application also provides an electrochemical disinfection device comprising the anode material.The present application realizes the selective generation of bromine radicals in high-chlorine and low-bromine water body by bromine doping, and at the same time, the electric perforation effect is generated by nanowire tip, so as to realize efficient disinfection and greatly reduce halogenated by-products, with the advantages of safety, speed, no secondary pollution.

Description

Technical Field

[0001] This invention relates to the field of electrochemical disinfection technology, specifically to a trace amount of Br-doped Co3O4 nanowire anode material, its preparation method, and an electrochemical disinfection device. Background Technology

[0002] Traditional advanced oxidation disinfection technologies, such as UV / persulfate activation, Fenton reaction, and ozone oxidation, rely on... • OH, SO4 •- and Cl • The strong oxidizing properties of highly reactive free radicals have shown great potential in wastewater disinfection. However, high energy consumption and secondary pollution from reagent addition severely restrict the large-scale engineering application of this technology. More importantly, the high oxidizing properties of halide ions (chloride ions) are a significant limitation. - ) and bromide ions (Br - These compounds are widely present in most water bodies and readily transform into reactive halogen species (RHS, such as HOCl, HOBr, Cl) in strongly oxidizing systems. • and Cl2 •- (etc.). On the one hand, halogen free radicals (such as Cl...) • E = 2.5 V; Br • (E = 2.0 V) has a high thermodynamic potential and fast reaction kinetics ( k ≈10 7 ~10 10 M -1 s -1 Free halogen species can enhance the degradation of target pollutants; however, on the other hand, free halogen species readily undergo electrophilic addition and substitution reactions with organic matrices, easily generating halogenated disinfection byproducts with higher toxicity than the parent compound. In particular, chlorine free radicals readily induce the formation of chlorinated intermediates, while bromine free radicals (Br₂)... • / Br2 •- The reaction of Cl with organic matter rarely produces brominated byproducts. Furthermore, when Cl... - Concentration much higher than Br - At that time, ClBr •- and Br2 •- It will be converted into Cl2 •- This further complicates the reaction pathway and increases the difficulty of toxicity control. Therefore, how to utilize the strong oxidizing properties of RHS while suppressing the formation of highly toxic halogenated byproducts is a key challenge in wastewater disinfection. Electrochemical water treatment technology has become a hot topic in water treatment research due to its renewable energy utilization, efficient pollutant degradation, and mild and controllable operating conditions. Especially in the regulation of active halogen species, electrochemical systems can achieve Cl... - / Br- The targeted regulation of transformation pathways provides the possibility of selectively promoting the formation of specific RHS and blocking the formation pathways of toxic byproducts while efficiently inactivating pathogens and degrading micropollutants. For example, the oxygen-vacancy-rich Co3O4 anode constructed by Zhang et al. optimizes Br - While achieving specific adsorption, the desorption energy barrier of the reaction intermediate was also modulated, thereby efficiently promoting the bromine evolution reaction; Gao's team synthesized a NiCo2O4 material with a high curvature needle-like structure, which utilized the tip-enhanced electric field effect to promote the bromine evolution reaction. − Enrichment and bromine radical generation. On the other hand, electroporation disinfection technology can use anolyte materials with nanowire structures to form an enhanced local electric field that destroys the external structure of microorganisms to inactivate them without the formation of byproducts.

[0003] Because most water bodies contain both chlorine and bromine, with chloride ion concentrations far exceeding bromide ion concentrations, traditional oxidation disinfection technologies tend to generate chlorinated reactive species. These species become the dominant factor in the inactivation of harmful microorganisms. Chlorine free radicals typically attack electron-rich sites (such as aromatic rings and double bonds) of organic pollutants via electrophilic attacks, forming chlorinated intermediates. While achieving pollutant degradation, this may also lead to the formation of chlorinated byproducts. Electrochemical water treatment technology can achieve selective generation of reactive species by optimizing the catalytic selectivity of electrode materials, regulating the interfacial environment, and precisely controlling the electrode potential. Traditional electrochemical anode materials mainly consist of commercially available size-stabilized anodes (DSA, such as RuO2 / IrO2 coatings). However, the high cost of precious metals limits their large-scale adoption. Therefore, developing an anode material based on industrial-grade non-precious metals that can selectively generate bromine free radicals in complex water bodies with high chlorine and low bromine levels for efficient disinfection, while simultaneously inhibiting the formation of chlorinated byproducts at the source and further improving disinfection efficiency and safety in conjunction with physical disinfection mechanisms, is a pressing issue that needs to be addressed. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the first objective of this invention is to provide a method for preparing a trace amount of Br-doped Co3O4 nanowire anode material, wherein Br-doped Co3O4 nanowires are grown in situ on a nickel foam substrate through hydrothermal reaction and calcination processes.

[0005] The second objective of this invention is to provide a trace amount of Br-doped Co3O4 nanowire anode material, prepared by the above-described method, having a nanowire tip structure, wherein the Br element is doped into the interior of the Co3O4 lattice by replacing the oxygen element in the lattice.

[0006] The third objective of this invention is to provide an electrochemical disinfection device comprising the aforementioned anode material, which selectively generates bromine free radicals in high-chlorine, low-bromine water, while simultaneously utilizing the nanowire tip structure to generate an electroporation effect, thereby synergistically achieving efficient disinfection and reducing the generation of halogenated byproducts.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a trace amount of Br-doped Co3O4 nanowire anode material includes the following steps: The nickel foam is immersed in an acid solution to remove the surface oxide layer, and then washed and dried to obtain pretreated nickel foam. Soluble cobalt salt, urea, ammonium fluoride, and sodium bromide are dissolved in water and mixed evenly to obtain a reaction precursor solution. The pretreated nickel foam is immersed in the reaction precursor solution and subjected to a hydrothermal reaction to grow a bromine-containing cobalt oxide precursor on the nickel foam substrate, thereby obtaining nickel foam loaded with the precursor. Urea is used as a precipitant, ammonium fluoride as a structure directing agent, and sodium bromide as a bromine dopant source. The nickel foam loaded with the precursor was calcined in an oxygen-containing atmosphere to obtain a trace amount of Br-doped Co3O4 nanowire anode material.

[0008] According to one example, the acid solution is a hydrochloric acid solution with a concentration of 2-4 M, and the soaking time is 15-30 min; the cleaning step involves rinsing with ethanol and ultrapure water for 1-3 min respectively.

[0009] Preferably, the hydrochloric acid solution concentration is 3 M, the soaking time is 20 min, and the cleaning step involves rinsing with ethanol and ultrapure water for 2 min each.

[0010] According to one example, the soluble cobalt salt is cobalt nitrate hexahydrate (Co(NO3)2·6H2O, CO(NH2)2), and in the reaction precursor solution, the concentration of cobalt nitrate hexahydrate is 60~80 mM, the concentration of urea (CO(NH2)2) is 130~150 mM, and the concentration of ammonium fluoride (NH4F) is 330~370 mM.

[0011] Preferably, the concentration of cobalt nitrate hexahydrate is 70 mM, the concentration of urea is 140 mM, and the concentration of ammonium fluoride is 350 mM.

[0012] According to one example, the concentration of sodium bromide is 0.5~1.5 mM.

[0013] According to one example, the hydrothermal reaction is carried out at a temperature of 100-140°C for a time of 8-14 hours.

[0014] Preferably, the concentration of sodium bromide (NaBr) is 1 mM, the temperature of the hydrothermal reaction is 120°C, and the time is 12 h.

[0015] According to one example, the calcination temperature is 350~450℃, the heating rate is 3~7℃ / min, and the calcination time is 1.5~2.5 h.

[0016] Preferably, the calcination temperature is 400℃, the heating rate is 5℃ / min, and the calcination time is 2 h.

[0017] According to one example, the ammonium fluoride acts as a structure-directing agent, selectively adsorbing fluoride ions onto specific crystal faces of the cobalt oxide precursor to control the crystal face growth rate and induce the formation of nanowire structures. Among these, fluoride ions (F...) - It has strong electronegativity and selectively adsorbs onto specific crystal faces of cobalt oxide precursors during hydrothermal reactions. By reducing the surface energy of these crystal faces, the growth rate of different crystal faces can be effectively controlled, thereby inducing anisotropic growth and ultimately forming nanowire structures.

[0018] A trace amount of Br-doped Co3O4 nanowire anode material is prepared by the above-mentioned preparation method, wherein the Br element is doped into the interior of the Co3O4 lattice by replacing the oxygen element in the lattice.

[0019] An electrochemical disinfection device includes a reaction vessel, a DC power supply, an anode assembly, and a cathode assembly; The anode assembly includes a trace amount of Br-doped Co3O4 nanowire anode material; The cathode assembly includes a cathode electrode; The anode assembly and the cathode assembly are disposed opposite to each other inside the reaction vessel and are electrically connected to the DC power supply, respectively.

[0020] According to one example, the cathode electrode is a titanium mesh electrode or a titanium plate electrode, and the distance between the anode assembly and the cathode assembly is 1 to 2 cm, preferably 1.5 cm.

[0021] This invention primarily utilizes electrochemical technology for wastewater disinfection. The key element is the preparation of a novel anode material. Traditional wastewater disinfection technologies, such as ultraviolet light, ozone, and chlorination (especially chlorine-containing disinfection systems), often produce more toxic halogenated byproducts, causing secondary water pollution. Studies have shown that bromine free radicals (Br2)... ·-Unlike chlorinated reactive species, bromine radicals have lower electronegativity and a larger van der Waals radius, making them thermodynamically less prone to free addition reactions and thus less likely to generate halogenated byproducts. Furthermore, in terms of inactivation mechanisms, bromine radicals are more selective and more likely to penetrate into cells with poor cell wall permeability, rapidly and efficiently disrupting bacterial metabolic systems and thus exhibiting higher oxidation efficiency. However, the concentration of bromine in natural water bodies is often very low (e.g., aquaculture wastewater, medical wastewater, etc.), making the selective generation of bromine radicals under low bromine concentration conditions a key technical challenge. On the other hand, novel nano-aperture perforation disinfection technology, which does not involve chemical reactions, can effectively control the generation of disinfection byproducts by physically destroying microbial cells. Therefore, the synergistic effect of bromine radicals and nano-aperture perforation can accelerate the inactivation of harmful microorganisms and control of disinfection byproducts. This invention constructs an electrochemical disinfection system that can selectively generate bromine radicals under high chlorine and low bromine conditions while also exhibiting an electroporation effect. The core of this invention is the preparation of a novel electrochemical anode material, achieving highly efficient disinfection while significantly reducing the generation of halogenated byproducts, making it a rapid and safe disinfection technology.

[0022] The present invention has the following advantages: This invention provides a trace amount of Br-doped Co3O4 nanowire anode material and its electrochemical disinfection application. First, by replacing oxygen in the Co3O4 lattice with Br in situ, the oxygen vacancy concentration is increased, endowing the material with the ability to selectively adsorb and activate bromide ions in high-chlorine, low-bromine water, thereby directionally generating bromine free radicals and fundamentally inhibiting the formation of chlorination byproducts. Second, the nanowire tip structure induced by the NH4F structure-directing agent generates a locally enhanced electric field under the action of an electric field, synergistically inducing an electroporation effect, physically destroying the microbial cell wall, and forming a dual disinfection effect with the chemical oxidation of bromine free radicals. Experiments show that the anode material can achieve complete inactivation of 10^7 CFU / mL E. coli under a constant voltage of 2.0V for 4 minutes, and the amount of halogenated byproducts generated is far lower than that of traditional MMO anodes.

[0023] Compared with existing technologies, this invention breaks through the limitations of traditional electrochemical disinfection relying on a single oxidation pathway. It organically combines chemical doping regulation with the physical structure of nanowires, achieving for the first time the synergistic effect of selective bromine radical generation and electroporation. This technical solution not only solves the key technical problem of the difficulty in generating bromine radicals in high-chlorine, low-bromine water bodies, but also improves disinfection efficiency through the physical perforation effect. While maintaining efficient inactivation of microorganisms, it significantly reduces the generation of halogenated byproducts, offering advantages such as safety, speed, and no secondary pollution. Attached Figure Description

[0024] Figure 1This is a schematic diagram of the workflow of the trace Br-doped Co3O4 nanowire anode material prepared in Example 1 of the present invention; wherein, 1 is nickel foam, 2 is Teflon lining of high-temperature reactor, 3 is stainless steel high-temperature reactor, 4 is oven, 5 is vacuum drying oven, and 6 is muffle furnace.

[0025] Figure 2 These are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the Br-doped Co3O4 nanowire anode material prepared in Example 1 of this invention; wherein, Figure 2 a is an SEM image of a nickel foam substrate. Figure 2 b and Figure 2 c shows SEM images of Br-Co3O4 at different magnifications. Figure 2 d is a TEM image of Br-Co3O4.

[0026] Figure 3 These are the energy dispersive spectral mapping results of the Br-doped Co3O4 nanowire anode material prepared in Example 1 of this invention; wherein, Figure 3 'a' represents the area to be scanned. Figure 3 b is an overlay image showing all elements. Figure 3 The diagrams for cf represent the distribution of Ni, Co, O, and Br elements, respectively.

[0027] Figure 4 This is a schematic diagram of the electrochemical disinfection device of the present invention; wherein, 7 is a cylindrical reaction cell, 8 is the anode material, 9 is a titanium mesh cathode, 10 is the reaction solution, 11 is a PTFE electrode clamp, 12 is a power supply wire, and 13 is a DC power supply.

[0028] Figure 5 This is a curve showing the disinfection effect of the Br-doped Co3O4 nanowire anode material prepared in Example 1 of this invention on Escherichia coli under different voltages (1.6 V, 1.8 V, 2.0 V, 2.2 V).

[0029] Figure 6 These are scanning electron microscope (SEM) images of Escherichia coli (E. coli) before and after the reaction; among them, Figure 6 'a' represents the E. coli before the reaction. Figure 6 b represents the Escherichia coli after the reaction.

[0030] Figure 7 This is a comparison of the sterilization effects of Br-doped Co3O4 nanowire anode materials prepared with different NaBr concentrations (0 mM, 0.5 mM, 1.0 mM, 1.5 mM).

[0031] Figure 8This is a comparison of the sterilization effects of Br-doped Co3O4 nanowire anode materials prepared at different hydrothermal temperatures (100°C, 120°C, 140°C).

[0032] Figure 9 This is a comparison of the sterilization effects of Br-doped Co3O4 nanowire anode materials prepared at different hydrothermal times (10 h, 12 h, 14 h).

[0033] Figure 10 This is a comparison chart showing the sterilization effects of Br-doped Co3O4 nanowire anode materials prepared at different calcination temperatures (350°C, 400°C, 450°C).

[0034] Figure 11 This is a comparison chart showing the amount of halogenated byproducts generated in the system after electrochemical sterilization between the Br-doped Co3O4 nanowire anode material prepared in Example 1 of this invention and the commercially available MMO anode in Comparative Example 2.

[0035] Figure 12 The EPR spectrum of the Br-doped Co3O4 nanowire anode material prepared in Example 1 of this invention after the addition of phenol shows typical six-line carbon center radical (CCR) characteristic signals, indirectly proving the generation of bromine radicals.

[0036] Figure 13 This is the high-resolution X-ray photoelectron spectroscopy (XPS) Br 3d spectrum of the Br-doped Co3O4 nanowire anode material prepared in Example 1 of this invention.

[0037] Figure 14 This is the X-ray photoelectron spectroscopy (XPS) O 1s high-resolution spectrum of the Br-doped Co3O4 nanowire anode material prepared in Example 1 of this invention. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field. Test methods in the following embodiments that do not specify specific experimental conditions are generally performed under conventional experimental conditions. Unless otherwise specified, the reagents and raw materials used in the present invention are all commercially available. Specifically, the reagents prepared in the experiments were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and the nickel foam substrate was purchased from Suzhou Keshenghe Metal Materials Co., Ltd. Example

[0039] Reference Figure 1 This embodiment provides a method for preparing a trace amount of Br-doped Co3O4 nanowire anode material, the specific steps of which are as follows: The reagents required for preparing the anode material are Co(NO3)2·6H2O, CO(NH2)2, NH4F, and NaBr. The anode substrate is selected as nickel foam (NF) with a size of 30 mm * 30 mm and a thickness of 1 mm. First, NF is immersed in a 3 M HCl solution for 20 minutes to remove the surface oxide layer, followed by rinsing with ethanol and ultrapure water for 2 minutes each, and then drying to obtain pretreated nickel foam 1.

[0040] A solution containing 70 mM Co(NO3)2·6H2O, 140 mM CO(NH2)2, 350 mM NH4F, and 1 mM NaBr was prepared in the order of Co(NO3)2·6H2O, CO(NH2)2, NH4F, and NaBr. NH4F acted as a structure-directing agent, with its fluoride ions selectively adsorbing onto specific crystal faces of the cobalt oxide precursor, controlling the crystal growth rate and inducing the formation of nanowire structures. 60 mL of the mixed solution and the pretreated NF were added to a 100 mL high-temperature reactor lined with Teflon (2), which was then placed in a stainless steel high-temperature reactor (3). The reactor was then placed in an oven (4) and hydrothermally heated at 120°C for 12 h. After natural cooling, the NF was removed, revealing the formation of a Co3O4 precursor material (NF-Co3O4) on the NF.

[0041] NF-Co3O4 was rinsed several times with ultrapure water and then dried in a vacuum drying oven at 60°C for 4 h. Subsequently, the NF-Co3O4 was transferred to a muffle furnace 6 and calcined at 400°C for 2 h at a heating rate of 5°C / min. After calcination, the resulting material was rinsed several times with ultrapure water and then dried in a 60°C oven for 4 h, finally yielding a Br-doped Co3O4 anode material with a nanowire structure (Br-Co3O4). XPS characterization results showed that Br element was incorporated into the Co3O4 lattice by substituting oxygen elements within the lattice. Example

[0042] This embodiment is basically the same as Example 1, except that the concentration of NaBr is adjusted to 0.5 mM when preparing the reaction precursor solution, while other conditions remain unchanged. Example

[0043] This embodiment is basically the same as Example 1, except that the concentration of NaBr is adjusted to 1.5 mM when preparing the reaction precursor solution, while other conditions remain unchanged. Example

[0044] This embodiment is basically the same as Embodiment 1, except that the temperature of the hydrothermal reaction is adjusted to 100°C, while other conditions remain unchanged. Example

[0045] This embodiment is basically the same as Embodiment 1, except that the temperature of the hydrothermal reaction is adjusted to 140°C, while other conditions remain unchanged. Example

[0046] This embodiment is basically the same as Embodiment 1, except that the hydrothermal reaction time is adjusted to 10 hours, while other conditions remain unchanged. Example

[0047] This embodiment is basically the same as Embodiment 1, except that the hydrothermal reaction time is adjusted to 14 hours, while other conditions remain unchanged. Example

[0048] This embodiment is basically the same as Embodiment 1, except that the calcination temperature is adjusted to 350°C, while other conditions remain unchanged. Example

[0049] This embodiment is basically the same as Embodiment 1, except that the calcination temperature is adjusted to 450°C, while other conditions remain unchanged.

[0050] Comparative Example 1 This comparative example is essentially the same as Example 1, except that NaBr was not added when preparing the reaction precursor solution, while other conditions remained unchanged. The resulting material is an undoped Co3O4 nanowire anode material.

[0051] Comparative Example 2 This comparative example uses a commercially available ruthenium-iridium titanium electrode (MMO, 30 mm × 30 mm in size, 1 mm thick) as the anode material for comparison with Example 1. This electrode is a commercially available size-stabilized anode (DSA) with a titanium substrate and a surface coated with oxides of ruthenium and iridium.

[0052] Example 1 of effect verification The Br-doped Co3O4 nanowire anode material prepared in Example 1 was selected as the test sample.

[0053] The morphology and structure of the Br-Co3O4 anode material prepared in Example 1 were characterized. Figure 2 Images are from scanning electron microscopy (SEM) and transmission electron microscopy (TEM), in which Figure 2 a is an SEM image of a nickel foam substrate. Figure 2 b and Figure 2 c shows SEM images of Br-Co3O4 at different magnifications. The results indicate that the prepared material has a distinct nanowire structure, with the nanowires growing uniformly on the surface of the nickel foam substrate. Figure 2 Image d is a TEM image of Br-Co3O4, which further confirms the morphology of the nanowires.

[0054] Figure 3 The results are the energy distribution surface scan (mapping) results for Br-Co3O4. Figure 3 'a' represents the area to be scanned. Figure 3 b is an overlay image showing all elements. Figure 3 Figures cf show the elemental distributions of Ni, Co, O, and Br, respectively. The results indicate that Co, O, and Br are uniformly distributed within the nanowire structure, confirming successful and uniform Br doping. XPS characterization results are shown below. Figure 13 and Figure 14 As shown, the Br 3d signal can be detected in Br-Co3O4, indicating successful Br doping. Furthermore, the doping of bromide ions by substituting oxygen in the Co3O4 lattice further increases the oxygen vacancy concentration, which can be confirmed by the O 1s spectrum. This indicates that the Br doping is not a simple surface adsorption, but rather enters the interior of the lattice.

[0055] Reference Figure 4 The electrochemical disinfection device of the present invention is a single-chamber reaction system, which generally includes a reaction vessel, a DC power supply 13, an anode assembly, and a cathode assembly. The reaction vessel is a cylindrical reaction cell 7. The anode assembly includes a trace amount of Br-doped Co3O4 nanowire anode material 8, and the cathode assembly is a titanium mesh cathode 9. The anode material 8 is the Br-Co3O4 nanowire anode material prepared in Example 1, and the cathode is a commercially available 30 mm × 30 mm titanium mesh electrode 9 with a thickness of 1 mm. The anode material 8 and the titanium mesh cathode 9 are disposed opposite each other in the reaction solution 10 and are respectively fixed by PTFE electrode clamps 11. They are electrically connected to the DC power supply 13 through a power supply wire 12, forming a complete electrochemical disinfection circuit.

[0056] Electrochemical disinfection was carried out under constant pressure conditions. The reaction volume was 100 mL, and the reaction solution consisted of 200 mM Na₂SO₄, 40 mM NaCl, and 1 mM NaBr, containing *E. coli* at a concentration of 10⁷ CFU / mL. The reaction time was set to 10 minutes. The disinfection effect was as follows: Figure 5 As shown, the disinfection effect under different voltages was measured, indicating that 2.0 V and 2.2 V conditions produced a very significant disinfection effect. 2.0 V was selected as the experimental condition for subsequent experiments.

[0057] Figure 6 These are SEM images of Escherichia coli (E. coli) before and after the reaction. Figure 6 a represents E. coli before the reaction, with smooth and intact cell surfaces and plump morphology; Figure 6b represents the *E. coli* after the reaction; obvious nanoscale pores appeared on the cell surface, indicating damage to the cell structure. This result demonstrates that the Br-Co3O4 nanowire anode material of this invention can generate a locally enhanced electric field under the action of an electric field, synergistically inducing an electroporation effect, physically destroying the microbial cell wall, and achieving highly efficient disinfection together with the chemical oxidation of bromine free radicals.

[0058] In summary, the trace Br-doped Co3O4 nanowire anode material prepared in Example 1 possesses a uniform nanowire structure, with Br successfully doped into the Co3O4 lattice. It exhibits excellent disinfection performance under various voltage conditions, with 2.0 V being the preferred voltage, achieving complete inactivation of 10^7 CFU / mL E. coli within 4 minutes of reaction. This material possesses a dual disinfection mechanism of selective bromine radical generation and electroporation effect, making it a highly efficient and rapid electrochemical disinfection anode material.

[0059] Example 2 of effect verification The Br-doped Co3O4 nanowire anode materials prepared in Examples 1, 2, and 3, as well as Comparative Example 1, were selected as test samples.

[0060] use Figure 4 The electrochemical disinfection device shown uses the aforementioned anode materials as anodes and a titanium mesh electrode as cathode, with an electrode spacing of 1.5 cm. The anode and cathode are fixedly connected by tetrafluoroplatinum electrode clamps and fixed within a cylindrical reaction vessel containing a reaction solution, which is connected to a DC power supply. The reaction system consists of 100 mL of a solution containing 200 mM Na₂SO₄, 40 mM NaCl, and 1 mM NaBr, with *Escherichia coli* (E. coli) at a concentration of 10⁷ CFU / mL added as the target microorganism. The disinfection reaction is carried out under a constant voltage of 2.0 V DC power supply for 10 min. Samples are taken before and after the reaction, and the cells are counted on eosin methylene blue agar using the plate spread method to calculate the cell density of *E. coli* after inactivation.

[0061] like Figure 7 As shown, the results indicate that the sterilization effect of the undoped Co3O4 nanowire anode material (Comparative Example 1) is limited, with the E. coli cell density remaining as high as 10^6.4 CFU / mL after the reaction. After doping with Br, the sterilization effect is significantly improved. When the NaBr concentration is 0.5 mM, the cell density decreases to 10^4.2 CFU / mL after the reaction. When the NaBr concentration is increased to 1.0 mM, the sterilization effect is optimal, with the cell density dropping to as low as 10^1 CFU / mL after the reaction. Further increasing the NaBr concentration to 1.5 mM slightly reduces the sterilization effect, with the cell density decreasing to 10^1.9 CFU / mL after the reaction.

[0062] Appropriate Br doping can significantly improve the electrochemical disinfection performance of Co3O4 nanowire anode materials, with an optimal NaBr doping concentration of 1.0 mM. Too low a Br doping concentration results in insufficient bromine radical generation, while too high a concentration may affect the material's crystal structure or lead to over-doping, both of which are detrimental to further improving the disinfection effect.

[0063] Example 3 of effect verification The Br-doped Co3O4 nanowire anode materials prepared in Examples 1, 4, and 5 were selected as test samples.

[0064] use Figure 4 The electrochemical disinfection device shown uses the aforementioned anode materials as the anodes and a titanium mesh electrode as the cathode, with an electrode spacing of 1.5 cm. The reaction system consists of 100 mL of a solution containing 200 mM Na₂SO₄, 40 mM NaCl, and 1 mM NaBr, with *E. coli* (E. coli) at a concentration of 10⁷ CFU / mL added as the target microorganism. The disinfection reaction is carried out under a constant voltage of 2.0 V DC power supply for 10 min. Samples are taken before and after the reaction, and the cells are counted on eosin methylene blue agar using the plate spread method to calculate the cell density of *E. coli* after inactivation.

[0065] like Figure 8 As shown, the results indicate that when the hydrothermal temperature is 100°C, the cell density of *E. coli* after the reaction is 10^3.5 CFU / mL; when the hydrothermal temperature is increased to 120°C, the disinfection effect is significantly improved, and the cell density after the reaction is as low as 10^0.4 CFU / mL; when the hydrothermal temperature is further increased to 140°C, the disinfection effect decreases slightly, and the cell density after the reaction is 10^1.4 CFU / mL. Therefore, 120°C is the preferred hydrothermal temperature. The material prepared under this condition has the best nanowire structure and Br doping effect, thus obtaining the best disinfection performance.

[0066] Example 4 of effect verification The Br-doped Co3O4 nanowire anode materials prepared in Examples 1, 6, and 7 were selected as test samples.

[0067] use Figure 4The electrochemical disinfection device shown uses the aforementioned anode materials as the anodes and a titanium mesh electrode as the cathode, with an electrode spacing of 1.5 cm. The reaction system consists of 100 mL of a solution containing 200 mM Na₂SO₄, 40 mM NaCl, and 1 mM NaBr, with *E. coli* (E. coli) at a concentration of 10⁷ CFU / mL added as the target microorganism. The disinfection reaction is carried out under a constant voltage of 2.0 V DC power supply for 10 min. Samples are taken before and after the reaction, and the cells are counted on eosin methylene blue agar using the plate spread method to calculate the cell density of *E. coli* after inactivation.

[0068] like Figure 9 As shown, the results indicate that when the hydrothermal time was 10 h, the E. coli cell density decreased to 10^3 CFU / mL after the reaction; when the hydrothermal time was extended to 12 h, the E. coli cell density further decreased to 10^0.8 ​​CFU / mL; further extending the hydrothermal time to 14 h resulted in a decrease in sterilization effect, with the cell density after the reaction reaching 10^1.9 CFU / mL. Therefore, 12 h is the optimal hydrothermal time, and the material prepared under this condition exhibits the best nanowire structure and Br doping effect.

[0069] Example 5 of effect verification The Br-doped Co3O4 nanowire anode materials prepared in Examples 1, 8, and 9 were selected as test samples.

[0070] use Figure 4 The electrochemical disinfection device shown uses the aforementioned anode materials as the anodes and a titanium mesh electrode as the cathode, with an electrode spacing of 1.5 cm. The reaction system consists of 100 mL of a solution containing 200 mM Na₂SO₄, 40 mM NaCl, and 1 mM NaBr, with *E. coli* (E. coli) at a concentration of 10⁷ CFU / mL added as the target microorganism. The disinfection reaction is carried out under a constant voltage of 2.0 V DC power supply for 10 min. Samples are taken before and after the reaction, and the cells are counted on eosin methylene blue agar using the plate spread method to calculate the cell density of *E. coli* after inactivation.

[0071] like Figure 10 As shown, the results indicate that when the calcination temperature is 350°C, the post-reaction E. coli cell density is 10^4.9 CFU / mL; when the calcination temperature is increased to 400°C, the sterilization effect is significantly improved, and the post-reaction cell density is as low as 10^0.9 CFU / mL; when the calcination temperature is further increased to 450°C, the sterilization effect decreases slightly, and the post-reaction cell density is 10^1.1 CFU / mL. Therefore, 400°C is the preferred calcination temperature, and the material prepared under this condition exhibits the best crystallinity and Br doping effect.

[0072] Example 6 of effect verification The trace Br-doped Co3O4 nanowire anode material prepared in Example 1 and the commercially available ruthenium-iridium-titanium electrode (MMO) in Comparative Example 2 were selected as test samples.

[0073] use Figure 4 The electrochemical disinfection device shown uses the two materials mentioned above as anodes and a titanium mesh electrode as cathode, with an electrode spacing of 1.5 cm. The reaction system consists of 100 mL of a solution containing 200 mM Na₂SO₄, 40 mM NaCl, and 1 mM NaBr, with *E. coli* (at a concentration of 10⁷ CFU / mL) added as the target microorganism. The disinfection reaction is carried out under a constant voltage of 2.0 V DC power supply for 10 min. After the reaction, the amount of halogenated byproducts generated is measured.

[0074] Experimental results are as follows Figure 11 As shown, the results indicate that after electrochemical sterilization using a commercially available MMO anode, a high concentration of halogenated byproducts was detected in the reaction system. After electrochemical sterilization using the Br-doped Co3O4 nanowire anode material prepared in Example 1 of this invention, the amount of halogenated byproducts generated in the reaction system was significantly reduced, far lower than that in the MMO anode system. The anode material of this invention effectively reduces the formation of halogenated byproducts by selectively generating bromine free radicals and inhibiting the generation of chlorine active species.

[0075] Example 7 of effect verification The Br-doped Co3O4 nanowire anode material prepared in Example 1 was selected as the test sample, and the undoped Co3O4 nanowire anode material prepared in Comparative Example 1 was selected as the control sample.

[0076] use Figure 4 The electrochemical disinfection device shown uses the two materials mentioned above as anodes and a titanium mesh electrode as cathode, with an electrode spacing of 1.5 cm. The reaction system is a 100 mL solution containing 200 mM Na₂SO₄, 40 mM NaCl, and 1 mM NaBr. The reaction is carried out under a constant voltage of 2.0 V DC power supply for 10 min. EPR spectroscopy is used to detect free radicals in the reaction system. A control experiment with added phenol is also included, indirectly demonstrating the presence of bromine free radicals through the reaction of phenol with bromine free radicals to generate carbon-centered radicals (CCR).

[0077] like Figure 12As shown, the results indicate that in the control group using Comparative Example 1, the EPR signal showed no obvious characteristic peaks, indicating that no obvious free radical signal was detected. Similarly, in the system using Example 1, no obvious bromine free radical signal was observed upon direct detection, which may be attributed to the instability of bromine free radicals, making them difficult to capture and detect in a timely manner. After adding phenol to the system using Example 1, a typical six-line characteristic signal appeared in the EPR spectrum, which is the characteristic spectrum of a carbon-center free radical (CCR). This CCR is generated by the hydrogen atom transfer or single-electron transfer reaction between bromine free radicals and phenol. These results verify that the anode material of this invention achieves selective generation of bromine free radicals under high-chlorine and low-bromine conditions through Br doping.

[0078] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a trace amount of Br-doped Co3O4 nanowire anode material, characterized in that, Includes the following steps: The nickel foam is immersed in an acid solution to remove the surface oxide layer, and then washed and dried to obtain pretreated nickel foam. Soluble cobalt salt, urea, ammonium fluoride and sodium bromide are dissolved in water and mixed evenly to obtain a reaction precursor solution; The pretreated nickel foam is immersed in the reaction precursor solution to carry out a hydrothermal reaction, and a bromine-containing cobalt oxide precursor is grown on the nickel foam substrate to obtain nickel foam loaded with the precursor. The nickel foam loaded with the precursor was calcined in an oxygen-containing atmosphere to obtain a trace amount of Br-doped Co3O4 nanowire anode material.

2. The preparation method according to claim 1, characterized in that, The acid solution is a hydrochloric acid solution with a concentration of 2-4M, and the soaking time is 15-30 min; the cleaning steps involve rinsing with ethanol and ultrapure water for 1-3 min respectively.

3. The preparation method according to claim 1, characterized in that, The soluble cobalt salt is cobalt nitrate hexahydrate. In the reaction precursor solution, the concentration of cobalt nitrate hexahydrate is 60-80 mM, the concentration of urea is 130-150 mM, and the concentration of ammonium fluoride is 330-370 mM.

4. The preparation method according to claim 1, characterized in that, The concentration of sodium bromide is 0.5~1.5 mM.

5. The preparation method according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 100-140℃ for 8-14 hours.

6. The preparation method according to claim 1, characterized in that, The calcination temperature is 350~450℃, the heating rate is 3~7℃ / min, and the calcination time is 1.5~2.5 h.

7. The preparation method according to claim 1, characterized in that, The ammonium fluoride acts as a structure directing agent, selectively adsorbing fluoride ions onto specific crystal faces of the cobalt oxide precursor to control the crystal face growth rate and induce the formation of nanowire structures.

8. A trace amount of Br-doped Co3O4 nanowire anode material, characterized in that, The material is prepared by any one of the preparation methods described in claims 1 to 7, wherein the Br element is doped into the interior of the Co3O4 lattice by replacing the oxygen element in the lattice.

9. An electrochemical disinfection device, characterized in that, Includes reaction vessel, DC power supply, anode assembly and cathode assembly; The anode assembly comprises the trace Br-doped Co3O4 nanowire anode material as described in claim 8; The cathode assembly includes a cathode electrode; The anode assembly and the cathode assembly are disposed opposite to each other inside the reaction vessel and are electrically connected to the DC power supply, respectively.

10. The electrochemical disinfection device according to claim 9, characterized in that, The cathode electrode is a titanium mesh electrode or a titanium plate electrode, and the distance between the anode assembly and the cathode assembly is 1~2 cm.

Images