Iron-nickel bimetallic carbon-based nanoszyme for synergistic electricity generation and wastewater treatment, electrode and preparation method and application thereof

Abstract

The application discloses a kind of iron-nickel bimetallic carbon-based nanoscale enzyme that can be synergized with power generation and wastewater treatment, electrode and its preparation method and application.The method selects iron-nitrogen complex with porous structure as carrier, nickel ions are enriched from solution containing nickel-containing complex by coordination chelation and electrostatic adsorption of carrier, nickel-iron precursor is formed, and iron-nickel bimetallic carbon-based nanoscale enzyme is prepared by gradient calcination under inert gas protection, which is modified on the surface of electrode to form iron-nickel bimetallic carbon-based nanoscale enzyme electrode, which can be used to assemble nanoscale enzyme fuel cell.The application not only realizes the resource utilization of nickel-containing wastewater, but also prepares nanoscale enzyme electrode material that can be synergized with power generation and wastewater treatment, and the preparation process is simple, which can be mass-produced.Iron-nickel bimetallic carbon-based nanoscale enzyme has good enzyme-like catalytic activity, and can be used in environmental governance, colorimetric sensing and fuel cell and other fields.

Description

Technical Field

[0001] This invention belongs to the field of nanoenzyme electrode material technology, and relates to an iron-nickel bimetallic carbon-based nanoenzyme, electrode, preparation method and application that can synergistically generate electricity and treat wastewater. Background Technology

[0002] Aromatic phenols are a class of highly toxic organic pollutants that pose a serious threat to ecological security and human health. Therefore, the detection and removal of aromatic phenols are crucial. Natural laccase, as a polyphenol oxidase, can efficiently catalyze the oxidation of polyphenols to water, possessing the characteristics of a green and efficient multifunctional biocatalyst, and has important application value in the fields of biosensing and pollutant degradation. In recent years, researchers have established intermolecular electron transfer pathways in enzyme biofuel cells (EBFCs) by simulating in vivo electron transfer, achieving the goal of co-generating electricity from organic wastewater treatment. However, the high cost, poor stability, and difficulty in recycling of natural laccase limit its practical application. In recent years, nanozymes, as an alternative to natural enzymes, have received widespread application and attention in the biochemical field due to their high stability. However, the catalytic activity of nanozymes still cannot match that of natural enzymes; how to develop efficient strategies to enhance their catalytic activity remains an important issue in the field of nanozymes.

[0003] The emergence of bimetallic carbon-based nanozymes has greatly improved the atom utilization rate of traditional nanozymes. The well-defined metal coordination structure also provides a clear experimental model for the catalytic mechanism of nanozymes. Furthermore, bimetallic carbon-based nanozymes can enhance enzyme-like catalytic selectivity through metal-metal complementarity and multi-site activation. Currently, common methods for preparing bimetallic carbon-based nanozymes include dual-solvent impregnation, sol-gel methods, vapor deposition, and ion exchange methods. However, these methods often suffer from complex preparation processes, difficulty in large-scale production, and low economic efficiency, hindering their practical engineering applications. Summary of the Invention

[0004] The purpose of this invention is to provide an iron-nickel bimetallic carbon-based nanozyme, electrode, and its preparation method and application that can synergistically generate electricity and treat wastewater. This method involves controlling the precursor iron-nitrogen complex and utilizing ligand chelation and electrostatic adsorption principles to adsorb nickel-containing complexes, thereby obtaining an iron-nickel bimetallic carbon-based nanozyme with controllable catalytic sites, simple operation, and scalable production. Based on this nanozyme, an iron-nickel bimetallic carbon-based nanozyme electrode is prepared, and the assembled single-enzyme nanozyme fuel cell can synergistically generate electricity and treat wastewater.

[0005] The technical solution to achieve the objective of this invention is:

[0006] The preparation method of iron-nickel bimetallic carbon-based nanozymes includes the following steps:

[0007] (1) Nickel enrichment:

[0008] The iron-nitrogen complex was added to a solution containing a nickel-containing complex, stirred at room temperature, collected by vacuum filtration, and dried to obtain the nickel-iron precursor.

[0009] (2) Anchoring of nickel:

[0010] The nickel-iron precursor was placed in a tube furnace and calcined using a gradient heating method under an inert atmosphere composed of nitrogen and argon to obtain a nickel-iron bimetallic carbon-based nanozyme.

[0011] The iron-nitrogen complexes described in this invention are iron-containing metal-organic framework materials, iron phthalocyanine, iron porphyrin, or iron-nitrogen compounds formed through in-situ synthesis, etc. They are prepared using common existing methods, selecting nitrogen-containing ligands to react with iron salts, and synthesizing iron-nitrogen complexes through solvothermal methods, in-situ synthesis methods, or sol-gel methods.

[0012] Preferably, in step (1), the nickel-containing complex is selected from one or more of nickel ethylenediaminetetraacetate (Ni-EDTA), nickel iminodiacetate (Ni-IDA), nickel nitrotriacetate (Ni-NTA), and nickel triethyltetraaminediacetate (Ni-TED).

[0013] Preferably, in step (1), the solution containing nickel complex is wastewater containing nickel complex, such as electroplating wastewater.

[0014] Preferably, in step (1), the nickel content in the solution containing the nickel complex is 5 ppm to 30 ppm.

[0015] Preferably, in step (2), the gradient heating calcination is as follows: first, the temperature is increased to 400℃ at a heating rate of 2-5℃ / min, and held for 0.5-2h, and then the temperature is increased to 800-900℃ at a heating rate of 2-5℃ / min, and held for 1-4h.

[0016] Preferably, in step (2), the flow rate of the inert gas is 20-50 mL / min.

[0017] The present invention also provides an iron-nickel bimetallic carbon-based nanozyme prepared by the above preparation method.

[0018] Furthermore, the present invention provides an iron-nickel bimetallic carbon-based nanoenzyme electrode, wherein the above-mentioned iron-nickel bimetallic carbon-based nanoenzyme is immobilized on the electrode surface.

[0019] The preparation method of the above-mentioned iron-nickel bimetallic carbon-based nanoelectrode includes the following steps:

[0020] The above-mentioned iron-nickel bimetallic carbon-based nanozyme and 0.5% Nafion solution were ultrasonically dispersed in ethanol, and then the dispersion was dropped onto the surface of a graphite felt (GF) electrode and dried to obtain an iron-nickel bimetallic carbon-based nanozyme / GF electrode.

[0021] The present invention also provides a nanoenzyme fuel cell, which is assembled from the above-mentioned iron-nickel bimetallic carbon-based nanoenzyme electrode.

[0022] Furthermore, the present invention provides the application of the above-mentioned nanoenzyme fuel cell in the catalytic oxidation of aromatic phenols.

[0023] The aromatic phenols described in this invention include, but are not limited to, 2,4-dichlorophenol (2,4-DCP), p-nitrophenol (PNP), and 4-chlorophenol (4-CP).

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) This invention utilizes iron-nitrogen complexes to adsorb nickel-containing complexes such as Ni-EDTA through ligand chelation and electrostatic adsorption. This Ni element loading method is universal.

[0026] (2) Nickel-containing complexes are widely present in electroplating wastewater. By chelating and adsorbing nickel-containing complexes such as Ni-EDTA in electroplating wastewater, the introduction of Ni element can be achieved, which can greatly reduce the preparation cost of nanozymes and realize the resource utilization of waste.

[0027] (3) The iron-nickel bimetallic carbon-based nanozyme prepared in this invention has obvious laccase-like activity and good reactivity to a variety of substrates.

[0028] (4) The nanoenzyme fuel cell assembled by the iron-nickel bimetallic carbon-based nanoenzyme electrode of the present invention can synergistically generate electricity and treat wastewater. At the same time, compared with biological enzymes, the nanoenzymes prepared have higher stability. Attached Figure Description

[0029] Figure 1 The image shows a scanning electron microscope (SEM) image of the iron-nickel bimetallic carbon-based nanozyme prepared in Example 1.

[0030] Figure 2 The image shows the X-ray diffraction (XRD) pattern of the iron-nickel bimetallic carbon-based nanozyme prepared in Example 1. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0032] Example 1

[0033] 1. The preparation of iron-nickel bimetallic carbon-based nanozymes, based on the principles of ligand chelation and electrostatic adsorption, specifically includes the following steps:

[0034] (1) Synthesis of iron-nitrogen complexes:

[0035] Zinc nitrate (Zn(NO3)2·6H2O) (3.272 g), ferric ammonium sulfate (NH4Fe(SO4)2) (0.241 g), and ferrous ammonium sulfate ((NH3)2Fe(SO4)2) (0.196 g) were dissolved in 250 ml of methanol to obtain solution 1. 2-methylimidazolium C5H8N2 (3.94 g) was dissolved in 250 ml of methanol to obtain solution 2. Solution 2 was poured into solution 1, stirred for 4 hours, centrifuged, washed, and freeze-dried to obtain an iron-containing metal-organic framework material (labeled Fe-ZIF-8).

[0036] (2) Nickel enrichment:

[0037] 0.5 g of Fe-ZIF-8 was added to 250 ml of Ni-EDTA solution with a Ni-EDTA concentration of 5 ppm. The mixture was stirred at room temperature for 4 h, collected by filtration, and then freeze-dried at -40 °C to obtain the iron-nickel precursor (labeled as FeNi-ZIF-8).

[0038] (3) Anchoring of nickel:

[0039] The FeNi-ZIF-8 precursor was placed in a tube furnace and calcined with a mixture of nitrogen and argon. A gradient heating method was used, first heating to 400℃ at a rate of 2℃ / min and holding for 0.5h, then heating to 900℃ at a rate of 3℃ / min and holding for 2h to obtain the iron-nickel bimetallic carbon-based nanozyme.

[0040] 2. Preparation of iron-nickel bimetallic carbon-based nanozyme / GF electrode

[0041] Weigh 5 mg of the above-mentioned iron-nickel bimetallic carbon-based nanozyme, dissolve it in 200 μL of ethanol, add 10 μL of Nafion solution, and sonicate for 30 min to obtain iron-nickel bimetallic carbon-based nanozyme ink; cut the pretreated graphite felt into a 1 cm × 2 cm rectangle, and add the iron-nickel bimetallic carbon-based nanozyme ink dropwise to a 1 cm × 1 cm area of ​​the graphite felt to obtain an iron-nickel bimetallic carbon-based nanozyme / GF electrode, which is labeled as nanozyme electrode No. 1.

[0042] The structure of iron-nickel bimetallic carbon-based nanozymes was characterized using scanning electron microscopy, such as... Figure 1 As shown. The results indicate that the iron-nickel bimetallic carbon-based nanozyme maintains a stable dodecahedral morphology. Its structure was characterized using X-ray diffraction (XRD), as shown... Figure 2As shown in the figure. After digestion, the loading content was characterized by inductively coupled plasma chromatography. The results showed that the Fe content in the iron-nickel bimetallic carbon-based nanozyme was 3.0 wt%, and the nickel content was 0.06 wt%.

[0043] A single-enzyme nanozyme fuel cell was assembled using nanozyme electrode No. 1. The substrate was 0.4 mM 2,4-DCP solution. The open-circuit voltage of the single-enzyme nanozyme fuel cell was measured to reach 75 mV, and the removal efficiency of 2,4-DCP reached 65%.

[0044] Example 2

[0045] This embodiment is basically the same as Example 1, except that the iron-nitrogen complex is iron phthalocyanine (FePc), and it is prepared through the following steps:

[0046] 2 mM FeCl2·4H2O and 8 mM 1,2-dimethylbenzene were mixed with 0.5 mL of 1,8-diazabicyclo(5,4,0)-7-undecene (DBU) and transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave. The mixture was reacted at 175 °C for 4 hours. After the reaction, the mixture was cooled to room temperature, filtered to obtain a purple precipitate, washed with ethanol, and dried at 60 °C for 8 hours to finally obtain the FePc precursor.

[0047] The iron-nickel bimetallic carbon-based nanozyme / GF electrode prepared in Example 2 is labeled as Nanozyme Electrode No. 2.

[0048] Example 3

[0049] This embodiment is basically the same as Example 1, except that the iron-nitrogen complex is synthesized using an in-situ synthesis method, and is prepared through the following steps:

[0050] 50 mg of SBA-15 (mesoporous molecular sieve), 100 mg of dopamine hydrochloride, and 200 mg of thiourea were added to a mixture of 15 mL of ethanol and 15 mL of deionized water. The mixture was stirred for 30 minutes. Then, 1 mL of FeCl3·6H2O aqueous solution was added, and the resulting mixture was continuously stirred at 60 °C to evaporate the solvent until the mixture became a solid, thus obtaining the iron-nitrogen complex.

[0051] The iron-nickel bimetallic carbon-based nanozyme / GF electrode prepared in Example 3 is labeled as Nanozyme Electrode No. 3.

[0052] Example 4

[0053] This embodiment is basically the same as Example 1, except that in S2, Ni-EDTA is replaced with Ni-IDA. The prepared iron-nickel bimetallic carbon-based nanozyme is labeled as No. 4.

[0054] Example 5

[0055] This embodiment is basically the same as Example 1, except that in S2, Ni-EDTA is replaced with Ni-NTA. The prepared iron-nickel bimetallic carbon-based nanozyme is labeled as No. 5.

[0056] Example 6

[0057] This embodiment is basically the same as Example 1, except that in S2, Ni-EDTA is replaced with Ni-TED. The prepared iron-nickel bimetallic carbon-based nanozyme is labeled as No. 6.

[0058] Comparative Example 1

[0059] This comparative example is basically the same as Example 1, except that the iron-nitrogen complex is replaced with hydrated iron hydroxide.

[0060] The iron-nickel bimetallic carbon-based nanozyme / GF electrode prepared in Comparative Example 1 is labeled as nanozyme electrode No. 7. The open-circuit voltage of the nanozyme fuel cell assembled with nanozyme electrode No. 7 is 44 mV, and the removal efficiency for 2,4-DCP is 41%. Specific data are shown in Table 1.

[0061] Comparative Example 2

[0062] This comparative example is basically the same as Example 1, except that Ni-EDTA is replaced with NiCl2.

[0063] The iron-nickel bimetallic carbon-based nanozyme / GF electrode prepared in Comparative Example 2 was labeled as Nanozyme Electrode No. 8. The open-circuit voltage of the nanozyme fuel cell assembled with Nanozyme Electrode No. 8 was 38mV, and the removal efficiency for 2,4-DCP was 27%. Specific data are shown in Table 1.

[0064] Comparative Example 3

[0065] This comparative example is basically the same as Example 1, except that the gradient heating method is replaced with a one-step heating pyrolysis, specifically heating to 900°C at a heating rate of 3°C / min and holding for two hours.

[0066] The iron-nickel bimetallic carbon-based nanozyme / GF electrode prepared in Comparative Example 3 was labeled as Nanozyme Electrode No. 9. The open-circuit voltage of the nanozyme fuel cell assembled with Nanozyme Electrode No. 9 was 55 mV, and the removal efficiency for 2,4-DCP was 41%. Specific data are shown in Table 1.

[0067] Comparative Example 4

[0068] This comparative example is basically the same as Example 1, except that the nitrogen-argon mixed gas protection is changed to pure nitrogen protection.

[0069] The iron-nickel bimetallic carbon-based nanozyme / GF electrode prepared in Comparative Example 4 is labeled as Nanozyme Electrode No. 10. The open-circuit voltage of the nanozyme fuel cell assembled with Nanozyme Electrode No. 10 is 47mV, and the removal efficiency for 2,4-DCP is 39%. Specific data are shown in Table 1.

[0070] Table 1. Performance comparison of nanoenzyme electrodes No. 2-10

[0071]

[0072] The above description is merely for illustrating the technical solution of the present invention, and 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. A method for preparing iron-nickel bimetallic carbon-based nanozymes, characterized in that, Includes the following steps: (1) Nickel enrichment: The iron-nitrogen complex was added to a solution containing a nickel-containing complex, stirred at room temperature, collected by filtration, and dried to obtain a nickel-iron precursor. The iron-nitrogen complex was an iron-containing metal-organic framework, iron phthalocyanine, iron porphyrin, or an iron-nitrogen compound made from a nitrogen-containing ligand and an iron salt. The nickel-containing complex was selected from one or more of Ni-EDTA, Ni-IDA, Ni-NTA, and Ni-TED. (2) Anchoring of nickel: The nickel-iron precursor was placed in a tube furnace and calcined under an inert atmosphere composed of nitrogen and argon using a gradient heating method to obtain the iron-nickel bimetallic carbon-based nanozyme. The gradient heating calcination was specifically carried out as follows: first, the temperature was increased to 400 ℃ at a heating rate of 2~5 ℃ / min and held for 0.5~2 h, and then the temperature was increased to 800~900 ℃ at a heating rate of 2~5 ℃ / min and held for 1~4 h; the flow rate of the inert gas was 20~50 mL / min.

2. The preparation method according to claim 1, characterized in that, The iron-nitrogen compounds prepared by nitrogen-containing ligands and iron salts can be prepared by solvothermal method, in-situ synthesis method or sol-gel method; the solution containing nickel-containing complexes is electroplating wastewater.

3. The preparation method according to claim 1, characterized in that, In step (1), the nickel content in the solution containing the nickel complex is 5 ppm to 30 ppm.

4. The iron-nickel bimetallic carbon-based nanozyme prepared by any one of the preparation methods according to claims 1 to 3.

5. A bimetallic iron-nickel carbon-based nanoelectrode, characterized in that, The iron-nickel bimetallic carbon-based nanozyme of claim 4 is fixed on the electrode surface.

6. The method for preparing the iron-nickel bimetallic carbon-based nanoelectrode according to claim 5, characterized in that, Includes the following steps: Iron-nickel bimetallic carbon-based nanozyme and 0.5% Nafion solution were ultrasonically dispersed in ethanol until uniform, and then the dispersion was dropped onto the surface of a graphite felt electrode and dried to obtain an iron-nickel bimetallic carbon-based nanozyme / GF electrode.

7. A nanoenzyme fuel cell, characterized in that, It is assembled from the iron-nickel bimetallic carbon-based nanoenzyme electrode as described in claim 5.

8. The application of the nanoenzyme fuel cell according to claim 7 in the catalytic oxidation of aromatic phenols.

9. The application according to claim 8, characterized in that, The aromatic phenols are 2,4-DCP, PNP, or 4-CP.

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