Preparation method of high-spin ni-doped co3o4 electrocatalyst and application thereof in production of singlet oxygen and sterilization

Abstract

The application belongs to the technical field of electrochemistry, and particularly relates to a high-spin Ni-doped Co3O4 electrocatalyst and application thereof in production of singlet oxygen and sterilization. 1 The high-spin Ni-Co3O4 is prepared by a simple hydrothermal method and a calcination method, taking a foamed nickel (NF) as a substrate and taking Co(NO3)2.6H2O and H2O2 as precursors, has a high spin state relative to Co3O4 without doping Ni, promotes efficient production of O2, and has a high catalytic activity. 1 Under a neutral condition, the Ni-Co3O4 electrochemical system can inactivate bacteria with a concentration of 1×10 6 CFU / mL within 5 min by using the catalytically generated O2. 1 The preparation method and the application of the application have important significance in optimizing electrocatalytic generation of O2 and microbial sterilization by a spin engineering strategy.

Description

Technical fields:

[0001] This invention belongs to the field of electrochemical technology, specifically relating to a high-spin Ni-doped Co3O4 electrocatalyst material, its preparation method, and its application in electrochemical sterilization. Background technology:

[0002] With the deterioration of the global environment, bacterial infections are becoming increasingly serious and posing a significant threat to human health. Singlet oxygen (… 1 O2 is the first electronically excited state of oxygen, exhibiting strong electrophilicity. It can effectively react with important components of bacterial cells, such as proteins, lipids, and nucleic acids. Furthermore, no corresponding [reactants] have been found within bacterial cells. 1 O2 antioxidant enzymes, 1 O2 exhibits higher sensitivity and selectivity in inactivating bacteria. Compared to other reactive oxygen species (ROS), 1 O2 is more resistant to environmental disturbances, has a longer lifespan, a greater diffusion distance, and is less likely to form halogenated disinfection byproducts during the sterilization process.

[0003] Currently, electrochemical advanced oxidation processes (AOPs) can effectively generate 1 O2. However, the main method is to catalyze the formation of H2O2 and persulfate. 1 O2, due to its reliance on external chemicals, tendency to generate byproducts, and complex operation, is limited in practical applications. Therefore, the direct generation of O2 from ground-state oxygen molecules via electrocatalysis is a promising approach. 1 O2 has the advantages of being easy to operate and environmentally friendly. Electrocatalytic O2 generation... 1 In the O2 process, the thermodynamics of adsorption and desorption between the active sites of the catalyst and the intermediate products, as well as the electron transfer processes and charge transfer within the catalyst, all influence the formation of O2. 1 Key factors in O2 reaction kinetics. However, current research on electrocatalytic O2 generation... 1 In the O2 process, the focus is mainly on the thermodynamics of adsorption and desorption between active sites and intermediate products. The regulation of catalysts mainly revolves around strategies such as constructing diverse nanostructures, introducing vacancies or defects, implementing alloying and crystal engineering, but the spin-related charge transfer and orbital interactions are ignored.

[0004] generate 1 The kinetics of O2 involve multiple mass and MO electron transfer coupling steps, among which several key oxygen intermediates ( * O2 - , *OOH) interacts with the outermost orbitals of the active site. Since the spin state of transition metal oxides is closely related to their catalytic activity, adjusting the spin state of the active site affects the energy of intermediate adsorption and bond dissociation, thus influencing the reaction pathway and kinetics. Therefore, this invention proposes a method for the efficient electrocatalytic generation of high-spin Ni-Co3O4 through asymmetric orbital hybridization. 1 O2 is used for bacterial inactivation. Summary of the Invention:

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and to develop a method for preparing a high-spin Ni-doped Co3O4 electrocatalyst material and its application in the production of singlet oxygen and sterilization. Ni-doping Co3O4 improves the efficiency of electrocatalytic oxygen production of singlet oxygen, achieving highly efficient bacterial inactivation.

[0006] To achieve the above objectives, the present invention provides an application of Ni-doped Co3O4 electrocatalyst in the generation of singlet oxygen. The Ni-doped Co3O4 electrocatalyst is a Ni-Co3O4 nanowire, with nickel doped at cobalt tetroxide octahedral sites. The Ni-doped Co3O4 electrocatalyst has a higher spin state than undoped Co3O4, and can efficiently catalyze the generation of singlet oxygen from O2.

[0007] This invention also provides the application of the above-mentioned Ni-doped Co3O4 electrocatalyst in electrochemical catalytic sterilization, utilizing Ni-Co3O4 nanowires to catalyze the generation of O2. 1 O2 was used to kill bacteria; using a Ni-Co3O4 nanowire electrode as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride (Ag / AgCl) electrode as the reference electrode, a potential of -0.2 to -1V was applied, and bacteria at a concentration of 10 were killed within 5 minutes. 6 The bacteria are CFU / mL; the concentration of the anhydrous sodium sulfate aqueous solution is 0.05-1.5M; the bacteria are one or more combinations of Gram-negative bacteria producing extended-spectrum β-lactamase Escherichia coli (ESBL-producing E. coli), Escherichia coli, Gram-positive bacteria methicillin-resistant Staphylococcus aureus (MRSA), and Staphylococcus aureus.

[0008] This invention also provides a method for preparing a Ni-doped Co3O4 electrocatalyst material, wherein the Ni-doped Co3O4 electrocatalyst has a higher spin state compared to undoped Co3O4, and the specific process steps are as follows:

[0009] (1) Cut the nickel foam into pieces no less than 1cm in size. 2The square shape was ultrasonicated in anhydrous ethanol for 10-50 min, and then ultrasonicated in 1-5M HCl aqueous solution for 10-50 min.

[0010] (2) Dissolve the precursors Co(NO3)2·6H2O, NH4F and urea in 20-80 mL of ultrapure water. The molar ratio of Co(NO3)2·6H2O:NH4F:urea is 1:2:5. Then stir magnetically for 20-40 min to form a pink solution. Add 1-6 mL of 30% H2O2 aqueous solution to obtain the precursor solution.

[0011] (3) Transfer the solution obtained in step (2) to a 30-100 mL stainless steel autoclave lined with polytetrafluoroethylene, and put the treated nickel foam into the autoclave; transfer the autoclave to an oven and keep it at 110-150℃ for 2-8 h; after the solution cools to room temperature, take it out, wash the sample with deionized water and vacuum dry it at 40-80℃ for 10-24 h to obtain Ni-Co-pre / NF;

[0012] (4) Place the dry Ni-Co-pre / NF in a muffle furnace, heat it in air at a heating rate of 2-10℃ / min, and anneal it at 200-500℃ for 1-4h to generate Ni-Co3O4 nanowires; which is a high spin Ni-doped Co3O4 electrocatalyst material.

[0013] The present invention also provides a high-spin Ni-doped Co3O4 electrocatalyst material obtained by the above preparation method, wherein the Ni-doped Co3O4 electrocatalyst is a Ni-Co3O4 nanowire, with nickel doped at cobalt tetroxide octahedral sites.

[0014] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention uses a simple method to dope Ni at the octahedral sites of Co3O4, forming high-spin Ni-Co3O4 through asymmetric orbital hybridization, thus realizing the conversion of the catalyst from a low-spin state to a high-spin state; since the high spin state is conducive to the adsorption and excitation of oxygen to generate singlet oxygen, it promotes... 1 Highly efficient O2 generation; under neutral conditions, the Ni-Co3O4 electrochemical system can inactivate 1×10⁻⁶ O₂ concentrations within 5 minutes. 6 CFU / mL of bacteria. This invention provides a simple method for preparing Ni-Co3O4, develops new applications for Ni-Co3O4, and demonstrates the role of spin engineering strategies in optimizing electrocatalytic generation. 1 The importance of O2 and microbial disinfection. Attached image description:

[0015] Figure 1This is a scanning electron microscope (SEM) image of the Ni-Co3O4 material of Example 1 of the present invention.

[0016] Figure 2 This is an electron energy dispersive spectroscopy (EDS) scan of the Ni-Co3O4 material of Example 1 of the present invention.

[0017] Figure 3 This is a high-resolution transmission electron microscope (HRTEM) image of the Ni-Co3O4 material in Example 1 of the present invention.

[0018] Figure 4 This is a schematic diagram of the magnetic (MH) measurement data results of Ni-Co3O4 and Co3O4 materials in Example 1 of the present invention.

[0019] Figure 5 This is a schematic diagram showing the Raman characterization results of the Ni-Co3O4 and Co3O4 materials involved in this invention.

[0020] Figure 6 This is a schematic diagram of the XPS characterization results of the Ni-Co3O4 and Co3O4 materials involved in this invention.

[0021] Figure 7 The materials produced in Example 4 of this invention are Ni-Co3O4 and Co3O4. 1 O2 electron paramagnetic resonance (EPR) test data graph, where A is 1 O2; B is a hydroxyl radical; C is a superoxide ion.

[0022] Figure 8 Plate plot showing the experimental results of the bactericidal effect of the Ni-Co3O4 material in Example 5 of this invention.

[0023] Figure 9 This is a flow cytometry test data graph of bacteria after sterilization with Ni-Co3O4 material for different times according to Example 5 of the present invention.

[0024] Figure 10 The images are scanning electron microscope (SEM) images of bacteria after sterilization with Ni-Co3O4 material for different times according to Example 5 of the present invention. Detailed implementation method:

[0025] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0026] Example 1:

[0027] This embodiment relates to a method for preparing a high-spin Ni-doped Co3O4 electrocatalyst material (Ni-Co3O4). Using nickel foam (NF) as a substrate and Co(NO3)2·6H2O and H2O2 as precursors, high-spin Ni-Co3O4 was prepared via a simple hydrothermal and calcination method. The specific steps are as follows:

[0028] (1) Cut the nickel foam into 2*2cm squares and sonicate in anhydrous ethanol for 30min, and sonicate in 3M HCl aqueous solution for 30min.

[0029] (2) Dissolve Co(NO3)2·6H2O (cobalt nitrate hexahydrate), NH4F (ammonium fluoride) and urea in 30 mL of ultrapure water. The molar concentrations of the three are 5 mM, 10 mM and 25 mM, respectively. Then stir magnetically for 30 min to form a pink solution. Then add 2 mL of H2O2 (hydrogen peroxide) aqueous solution with a mass concentration of 30%.

[0030] (3) Transfer the solution obtained in step (2) to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene, and put the foamed nickel treated in step (1) into the autoclave; transfer the autoclave to an oven and keep it at 120°C for 4 h; after the solution cools to room temperature, take it out, wash the sample with deionized water, and vacuum dry it at 60°C for 10 h to obtain Ni-Co-pre / NF;

[0031] (4) The dried Ni-Co-pre / NF was placed in a muffle furnace and heated at a rate of 5℃ / min in air, and annealed at 350℃ for 2h to generate Ni-Co3O4 nanowires, i.e. Ni-doped Co3O4 electrocatalyst.

[0032] In this embodiment, the prepared Ni-Co3O4 electrocatalyst was characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and high-resolution transmission electron microscopy (HRTEM). The characterization results are as follows: Figures 1-3 As shown.

[0033] from Figure 1 The SEM image shows that the surface of NF is uniformly covered with densely packed Ni-Co3O4 nanowires.

[0034] from Figure 2 The electron energy dispersive spectroscopy (EDS) scan shows that Co, Ni, and O elements are evenly distributed, indicating successful Ni doping.

[0035] from Figure 3 The HRTEM image shows that the Ni-Co3O4 nanowires exhibit a rough porous structure with a large specific surface area, which is beneficial for O2 adsorption.

[0036] This embodiment also characterized the Ni-Co3O4 electrocatalyst using magnetic properties (MH), Raman spectroscopy, and XPS, with an undoped low-spin Co3O4 electrocatalyst as a control. The results are as follows: Figure 4-6 As shown.

[0037] from Figure 4 The MH plots show that the nonlinear hysteresis loop curve and non-zero residual magnetization of Ni-Co3O4 are more pronounced. Furthermore, the saturation magnetization and coercivity of Ni-Co3O4 are both higher than those of Co3O4, indicating that Ni doping leads to more spin electrons, thereby transitioning the magnetic structure from a low-spin state to a high-spin state.

[0038] from Figure 5 and Figure 6 It can be concluded that the nickel in Ni-Co3O4 is miscible at the cobalt tetroxide octahedral sites.

[0039] The preparation method of the Co3O4 electrocatalyst differs from that of the Ni-Co3O4 electrocatalyst in that the 2 mL of H2O2 in step (2) is replaced by 2 mL of ultrapure water, while the other steps are the same.

[0040] Example 2:

[0041] This embodiment relates to a method for preparing a high-spin Ni-doped Co3O4 electrocatalyst material (Ni-Co3O4). The difference from Example 1 is that the volume of the 30% H2O2 (hydrogen peroxide) aqueous solution added in step (2) is 1 mL. The other steps are the same, and the high-spin Ni-doped Co3O4 electrocatalyst material is prepared.

[0042] Example 3:

[0043] This embodiment relates to a method for preparing a high-spin Ni-doped Co3O4 electrocatalyst material (Ni-Co3O4). The difference from Example 1 is that the volume of the 30% H2O2 (hydrogen peroxide) aqueous solution added in step (2) is 6 mL. The other steps are the same, and the high-spin Ni-doped Co3O4 electrocatalyst material is prepared.

[0044] Example 4:

[0045] This embodiment relates to the electrocatalyst Ni-Co3O4 and Co3O4 production prepared in Example 1. 1 O2 performance testing: The specific steps are as follows:

[0046] (1) Prepare a 0.1M anhydrous sodium sulfate aqueous solution as the electrolyte. Before energizing, pass oxygen for 10 minutes to ensure that there is sufficient oxygen in the electrolyte.

[0047] (2) Using an electrochemical workstation, a three-electrode catalytic system was employed: a Ni-Co3O4 nanowire electrode as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride (Ag / AgCl) electrode as the reference electrode, to catalyze the generation of O2 by applying a potential of -0.6V. 1 O2;

[0048] (3) Electron paramagnetic resonance (EPR) technology was used to further detect free radical species, with tetramethylpiperidone (TEMP) used as... 1 O2 scavenger, after mixing 100 electrolyte with 1 mL LTEMP (50.0 mM) solution in step (2), the electrocatalyst Ni-Co3O4 was generated by EPR testing. 1 The performance of O2 was assessed, and superoxide ions and hydroxyl radicals in the electrolyte were detected by EPR.

[0049] Using Co3O4 electrocatalyst as the working electrode, the production of Co3O4 was determined under the same conditions using the method described above. 1 The properties of O2 and the presence of superoxide ions in the electrolyte. Results are as follows: Figure 7 As shown.

[0050] from Figure 7 As can be seen from A, Ni-Co3O4 can catalyze the generation of O2 more efficiently than Co3O4. 1 O2.

[0051] from Figure 7 As can be seen from B, Ni-Co3O4 nanowires are produced. 1 No hydroxyl radicals were detected during the O2 process, indicating that no hydroxyl radicals were generated, suggesting that the Ni-Co3O4 nanowires produced... 1 O2 intermediates are not hydroxyl radicals.

[0052] from Figure 7 As can be seen from C, Ni-Co3O4 nanowires are produced 1 Superoxide ions were detected during the O2 process, while Co3O4 was produced. 1 No superoxide ions were detected during the O2 process, indicating that both produced... 1 The intermediate processes of O2 are different.

[0053] The process of producing singlet oxygen using Ni-Co3O4 electrocatalyst is as follows:

[0054] *+O2+e - →*O2 - (1)

[0055] *O2 - +H₂O→*+·OOH+OH - (2)

[0056] ·OOH+*O2 - →HO4 - →OOH - + 1 O2 (3)

[0057] The asterisk (*) indicates an adsorption site of the Ni-Co3O4 electrocatalyst material.

[0058] Example 5:

[0059] This embodiment relates to the application of Ni-Co3O4 prepared in Example 1 in electrochemical sterilization. The sterilization performance was tested using the Ni-Co3O4 electrochemical system established in Example 4. The specific steps are as follows:

[0060] (1) Gram-negative bacteria, extended-spectrum β-lactamase-producing Escherichia coli (ESBL-producing E. coli) was used as the model bacteria; the single clone of bacteria on LB solid medium was transferred to 50 mL of LB liquid medium and cultured in a shaker at 37 °C and 150 rpm / min for 12 h to reach the logarithmic growth phase.

[0061] (2) Bacteria in the logarithmic growth phase were added to a 0.1M anhydrous sodium sulfate aqueous solution to prepare an electrolyte containing bacteria. The bacterial concentration in the electrolyte was determined to be 10 using a McFarland turbidimeter. 6 CFU / mL, 30 mL of electrolyte was added to the electrolytic cell. A Ni-Co3O4 nanowire electrode was used as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride (Ag / AgCl) electrode as the reference electrode. Under sufficient oxygen conditions, a potential of -0.6 V was applied to catalyze the generation of O2 on the Ni-Co3O4 nanowire electrode. 1 O2;

[0062] (3) Using disposable syringes, the bacterial concentration of (2) above was 10 at different catalytic times. 6 The electrolyte was used to transfer bacterial cultures treated for different times to LB solid medium and incubated in a constant temperature incubator at 37℃ for 24 h. The number of colonies on the solid medium was then observed.

[0063] (4) Use disposable syringes to extract electrolytes from (2) above at different catalytic times, use bacterial live / dead staining agent (PI / Styo9) to perform bacterial live / dead staining, and use flow cytometer to test the bacterial status in bacterial solutions treated for different times.

[0064] (5) Use disposable syringes to extract the electrolyte from (2) above at different catalytic times, centrifuge at 4000 rpm, and collect the bacterial cells in 5-10 min; after dehydration with ethanol, fix with 2.5% glutaraldehyde, and dry with carbon dioxide at the critical point to obtain bacterial powder; observe the state of bacteria in the bacterial solution at different treatment times by scanning electron microscopy.

[0065] In this embodiment, flow cytometry and scanning electron microscopy (SEM) were used to characterize bacteria treated with the Ni-Co3O4 system for different times. The characterization results are as follows: Figures 8-10 As shown.

[0066] from Figure 8 The bacterial plate graph shows that treatment with the Ni-Co3O4 system for 5 minutes can kill bacteria at a concentration of 10. 6 CFU / mL of bacteria.

[0067] from Figure 9 The flow cytometry results show that after 4 minutes of treatment with the Ni-Co3O4 system, most bacterial cell membranes were damaged; after 8 minutes, most bacterial cells were severely damaged, and DNA leakage and degradation were observed.

[0068] from Figure 10 The SEM images show that before treatment with the Ni-Co3O4 system, the bacterial cells had a normal rod-shaped morphology and an intact, smooth cell membrane. After 4 minutes of treatment with the Ni-Co3O4 system, the bacteria deformed, and the cell membrane changed, forming pits. After 8 minutes of treatment with the Ni-Co3O4 system, the bacterial cell membrane ruptured significantly and became completely deformed.

[0069] In this embodiment, the method described above was used to test the effect of Ni-Co3O4 on bacteria at a concentration of 10. 6 The bactericidal properties of the Ni-Co3O4 system against Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), and Staphylococcus aureus (SSA) at CFU / mL were tested. The results showed that the Ni-Co3O4 system could kill Escherichia coli in 5 min and methicillin-resistant MRSA and SSA in 25 min.

[0070] This embodiment also uses the Ni-Co3O4 system to sterilize hospital wastewater, which also has a very good sterilization effect.

Claims

1. The application of a Ni-doped Co3O4 electrocatalyst in the generation of singlet oxygen, characterized in that, The Ni-doped Co3O4 electrocatalyst is a Ni-Co3O4 nanowire with nickel doped at cobalt tetroxide octahedral sites. Compared with undoped Co3O4, the Ni-doped Co3O4 electrocatalyst has a higher spin state and can efficiently catalyze the generation of singlet oxygen from O2. The specific steps for preparing the Ni-doped Co3O4 electrocatalyst are as follows: (1) Dissolve the precursors Co(NO3)2•6H2O, NH4F and urea in ultrapure water, stir magnetically to form a pink solution, and then add H2O2 aqueous solution to form a precursor solution; (2) Mix the precursor solution with the cleaned nickel foam and then carry out a hydrothermal reaction; after the solution is cooled to room temperature, take it out, wash the sample and vacuum dry it to obtain Ni-Co-pre / NF; (3) Place the dried Ni-Co-pre / NF in a muffle furnace and anneal it at 200-500℃ for 1-4h to generate Ni-Co3O4 nanowires; that is, Ni-doped Co3O4 electrocatalyst material.

2. The application of the Ni-doped Co3O4 electrocatalyst according to claim 1 in the generation of singlet oxygen, characterized in that, O2 generation catalyzed by Ni-Co3O4 nanowires 1 O2 is used for electrochemical catalytic sterilization.

3. The application of the Ni-doped Co3O4 electrocatalyst according to claim 2 in the generation of singlet oxygen, characterized in that, Using a Ni-Co3O4 nanowire electrode as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride (Ag / AgCl) electrode as the reference electrode, a potential of -0.2 to 1 V was applied to kill a concentration of 10 within 5 minutes. 6 CFU / mL of bacteria.

4. The application of the Ni-doped Co3O4 electrocatalyst according to claim 3 in the generation of singlet oxygen, characterized in that, The bacteria are one or both of Escherichia coli and Staphylococcus aureus.

5. The application of the Ni-doped Co3O4 electrocatalyst according to claim 4 in the generation of singlet oxygen, characterized in that, Escherichia coli includes extended-spectrum β-lactamase-producing Escherichia coli; Staphylococcus aureus includes methicillin-resistant Staphylococcus aureus.

6. The application of the Ni-doped Co3O4 electrocatalyst according to claim 1 in the generation of singlet oxygen, characterized in that, The processing method for nickel foam is as follows: cut the nickel foam into pieces no less than 1cm in size. 2 The square shape was ultrasonicated in anhydrous ethanol for 10-50 min, and then ultrasonicated in 1-5M HCl aqueous solution for 10-50 min.

7. The application of the Ni-doped Co3O4 electrocatalyst according to claim 1 in the generation of singlet oxygen, characterized in that, The molar concentration ratio of Co(NO3)2•6H2O, NH4F and urea in the pink solution is 1:2:5; the mass concentration of the H2O2 aqueous solution is 30%; the volume ratio of the added H2O2 aqueous solution to the volume of the pink solution is (1-6):(20-80).

8. The application of the Ni-doped Co3O4 electrocatalyst according to claim 1 in the generation of singlet oxygen, characterized in that, Step (2) The hydrothermal reaction temperature is 110-150℃ and the time is 2-8h; the vacuum drying temperature is 40-80℃ and the time is 10-24h.

9. The application of the Ni-doped Co3O4 electrocatalyst according to claim 1 in the generation of singlet oxygen, characterized in that, Step (3) The heating rate of the muffle furnace is 2-10℃ / min.

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