Iron-nickel bimetallic carbon-based nano-enzyme capable of synergistically generating electricity and treating wastewater, electrode and preparation method and application of iron-nickel bimetallic carbon-based nano-enzyme

Abstract

The invention discloses an iron-nickel bimetallic carbon-based nano enzyme capable of synergistically generating electricity and treating wastewater, an electrode and a preparation method and application of the iron-nickel bimetallic carbon-based nano enzyme. The method comprises the following steps: selecting an iron-nitrogen complex with a porous structure as a carrier, enriching nickel ions from a solution containing a nickel-containing complex through coordination chelation and electrostatic adsorption of the carrier to form a nickel-iron precursor, then carrying out gradient calcination under the protection of inert gas to prepare an iron-nickel bimetallic carbon-based nano-enzyme, modifying the surface of an electrode with the iron-nickel bimetallic carbon-based nano-enzyme, and finally preparing the nickel-iron bimetallic carbon-based nano-enzyme. The prepared iron-nickel bimetallic carbon-based nano-enzyme electrode can be used for assembling a nano-enzyme fuel cell. According to the method, recycling of the nickel-containing wastewater is achieved, the nano-enzyme electrode material capable of cooperatively generating electricity and treating the wastewater is prepared, the preparation process is simple, large-scale production can be achieved, and the iron-nickel bimetallic carbon-based nano-enzyme has good enzyme-like catalytic activity and can be applied to the fields of environmental governance, colorimetric sensing, fuel cells and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanozyme electrode materials, and relates to an iron-nickel bimetallic carbon-based nanozyme, an electrode, and a preparation method and application thereof that can synergistically generate electricity and treat wastewater. Background Art

[0002] Aromatic phenols are a class of highly toxic organic pollutants that pose a serious threat to ecological safety and human health. Therefore, the detection and removal of aromatic phenols are crucial. As a polyphenol oxidase, natural laccase can efficiently catalyze the oxidation of polyphenols to generate water, and has 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, by simulating in vivo electron transfer, researchers have established an intermolecular electron transfer pathway in an enzyme biofuel cell (EBFC) to achieve the purpose of synergistically generating electricity and treating organic wastewater. However, the high cost, poor stability and difficulty in recycling of natural laccase limit its practical application. In recent years, as an alternative to natural enzymes, nanozymes have been widely used and concerned in the biochemical field due to their high stability. However, the catalytic activity of nanozymes still cannot compare with that of natural enzymes. How to develop efficient strategies to improve their catalytic activity remains an important topic in the field of nanozymes.

[0003] The emergence of bimetallic carbon-based nanozymes has greatly improved the atomic utilization rate of traditional nanozymes. The clear metal coordination structure can also provide a clear experimental model for the catalytic mechanism of nanozymes, and bimetallic carbon-based nanozymes can improve the enzyme-like catalytic selectivity through metal-metal complementarity and multi-point activation. Currently, common preparation methods for bimetallic carbon-based nanozymes include double-solvent impregnation method, sol-gel method, chemical vapor deposition method, ion exchange method, etc. However, these methods often have problems such as complex preparation processes, difficulty in large-scale production, and low economy, and cannot be applied to actual engineering. Summary of the Invention

[0004] The purpose of the present invention is to provide an iron-nickel bimetallic carbon-based nanozyme, an electrode, and a preparation method and application thereof that can synergistically generate electricity and treat wastewater. This method regulates the precursor iron-nitrogen complex, and adsorbs the nickel-containing complex by using the principle of ligand chelation and electrostatic adsorption to prepare 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 a single-enzyme nanozyme fuel cell assembled can synergistically generate electricity and treat wastewater.

[0005] The technical solution to achieve the purpose of the present invention is as follows:

[0006] A preparation method of an iron-nickel bimetallic carbon-based nanozyme, comprising the following steps:

[0007] (1) Enrichment of nickel:

[0008] Add an iron-nitrogen complex to a solution containing a nickel complex, stir at room temperature, collect by suction filtration, and dry to obtain a nickel-iron precursor.

[0009] (2) Anchoring of nickel element:

[0010] Place the nickel-iron precursor in a tubular furnace and calcine it in a gradient heating manner under the protection of an inert atmosphere composed of nitrogen and argon to obtain an iron-nickel bimetallic carbon-based nanozyme.

[0011] The iron-nitrogen complex described in the present invention is an iron-containing metal-organic framework material, iron phthalocyanine, iron porphyrin, or an iron-nitrogen compound formed by in-situ synthesis, etc. It is prepared by existing common methods. Select a nitrogen-containing ligand to react with an iron salt, and synthesize the iron-nitrogen complex by a solvothermal method, an in-situ synthesis method, a sol-gel method, etc.

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

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

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

[0015] Preferably, in step (2), the gradient heating calcination is specifically as follows: First, heat up to 400 °C at a heating rate of 2 - 5 °C / min, keep the temperature for 0.5 - 2 h, and then continue to heat up to 800 - 900 °C at a heating rate of 2 - 5 °C / min, and keep the temperature for 1 - 4 h.

[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 nanozyme electrode, and the above iron-nickel bimetallic carbon-based nanozyme is fixed on the surface of the electrode.

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

[0020] The above-mentioned iron-nickel bimetallic carbon-based nanozyme and 0.5% Nafion solution were ultrasonically dispersed evenly 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 nanozyme fuel cell assembled from the above-mentioned iron-nickel bimetallic carbon-based nanozyme electrode.

[0022] Furthermore, the present invention provides the application of the above-mentioned nanozyme fuel cell in the catalysis of aromatic phenol oxidation.

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

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

[0025] (1) The present invention uses iron-nitrogen complexes to adsorb nickel-containing complexes such as Ni-EDTA through ligand chelation and electrostatic adsorption, and this method of loading Ni element has universality.

[0026] (2) Nickel-containing complexes widely exist in electroplating wastewater. By chelating and adsorbing nickel-containing complexes such as Ni-EDTA in electroplating wastewater, the introduction of Ni element is realized. On the one hand, the preparation cost of the nanozyme is greatly reduced, and at the same time, the resource treatment of waste is realized.

[0027] (3) The iron-nickel bimetallic carbon-based nanozyme prepared by the present invention has obvious laccase-like activity and good reactivity towards various substrates.

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

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

[0030] Figure 2 It is an X-ray diffraction (XRD) image of the iron-nickel bimetallic carbon-based nanozyme prepared in Example 1. Detailed Embodiments

[0031] The present invention will be further described in detail below with specific embodiments and drawings.

[0032] Example 1

[0033] 1. Preparation of iron-nickel bimetallic carbon-based nanozyme, based on the principle of ligand chelation and electrostatic adsorption, specifically including the following steps:

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

[0035] Dissolve zinc nitrate (Zn(NO 3 ) 2 ·6H 2 O) (3.272 g), ammonium ferric sulfate (NH 4 Fe(SO 4 ) 2 )(0.241 g), ammonium ferrous sulfate ((NH 3 ) 2 Fe(SO 4 ) 2 )(0.196 g) in 250 ml of methanol to obtain solution 1. Dissolve 2-methylimidazole C 5 H 8 N 2 (3.94 g) in 250 ml of methanol to obtain solution 2. Pour solution 2 into solution 1, stir for 4 hours, centrifuge, wash, and freeze-dry to obtain an iron-containing metal-organic framework material (labeled Fe-ZIF-8).

[0036] (2) Enrichment of nickel:

[0037] Add 0.5 g of Fe-ZIF-8 to 250 ml of Ni-EDTA solution with a Ni-EDTA concentration of 5 ppm, stir at room temperature for 4 h, filter and collect, and then freeze-dry at -40 °C to obtain an iron-nickel precursor (labeled FeNi-ZIF-8).

[0038] (3) Anchoring of nickel element:

[0039] Place the FeNi-ZIF-8 precursor in a tubular furnace, introduce a mixture of nitrogen and argon during the calcination process, and use a gradient heating method. First, heat at a rate of 2 °C / min to 400 °C and hold for 0.5 h, then continue to heat at a rate of 3 °C / min to 900 °C and hold for 2 h 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 ultrasonicate for 30 min to obtain an iron-nickel bimetallic carbon-based nanozyme ink; cut the pretreated graphite felt into a rectangle of 1 cm × 2 cm, and dropwise add the iron-nickel bimetallic carbon-based nanozyme ink to the area of 1 cm × 1 cm of the graphite felt to obtain an iron-nickel bimetallic carbon-based nanozyme / GF electrode, which is labeled as the No. 1 nanozyme electrode.

[0042] The structure of the iron-nickel bimetallic carbon-based nanozyme was characterized by scanning electron microscopy, as Figure 1 shown. The results show that the iron-nickel bimetallic carbon-based nanozyme maintains a stable dodecahedral morphology. Its structure was characterized by X-ray diffractometer (XRD), as Figure 2 shown. After digestion treatment, its loading amount was characterized by inductively coupled plasma chromatography. The results show that the Fe content in the iron-nickel bimetallic carbon-based nanozyme is 3.0 wt%, and the nickel content is 0.06 wt%.

[0043] A single-enzyme nanozyme fuel cell was assembled with the No. 1 nanozyme electrode. The oxidation substrate was a 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 example is basically the same as Example 1, and the only difference is that the iron-nitrogen complex is selected as iron phthalocyanine (FePc), which is prepared by the following steps:

[0046] Mix 2 mM of FeCl 2 ·4H 2 O and 8 mM of 1,2-dimethylbenzene with 0.5 mL of 1,8-diazabicyclo(5,4,0)-7-undecene (DBU), transfer it to a stainless-steel autoclave with a PTFE lining of 100 mL capacity, and react at 175 °C for 4 hours. After the reaction, cool to room temperature, filter to obtain a purple precipitate, wash it with ethanol and dry it 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 was labeled as the No. 2 nanozyme electrode.

[0048] Example 3

[0049] This example is basically the same as Example 1, and the only difference is that the synthesis method of the iron-nitrogen complex is selected as the in-situ synthesis method, which is prepared by 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 mixed solution of 15 mL of ethanol and 15 mL of deionized water, and the resulting mixture was stirred for 30 minutes. Then, 1 mL of an aqueous solution of FeCl 3 ·6H 2 O was added, and the resulting mixture was continuously stirred at 60 °C to evaporate the solvent until the mixture became a solid, obtaining an iron-nitrogen complex.

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

[0052] Example 4

[0053] This example was basically the same as Example 1, and the only difference was that in S2, Ni-EDTA was changed to Ni-IDA. The prepared iron-nickel bimetallic carbon-based nanozyme was labeled as No. 4.

[0054] Example 5

[0055] This example was basically the same as Example 1, and the only difference was that in S2, Ni-EDTA was changed to Ni-NTA. The prepared iron-nickel bimetallic carbon-based nanozyme was labeled as No. 5.

[0056] Example 6

[0057] This example was basically the same as Example 1, and the only difference was that in S2, Ni-EDTA was changed to Ni-TED. The prepared iron-nickel bimetallic carbon-based nanozyme was labeled as No. 6.

[0058] Comparative Example 1

[0059] This comparative example was basically the same as Example 1, and the only difference was that the iron-nitrogen complex was replaced with hydrated iron hydroxide.

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

[0061] Comparative Example 2

[0062] This comparative example was basically the same as Example 1, and the only difference was that Ni-EDTA was changed to NiCl 2 .

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

[0064] Comparative Example 3

[0065] This comparative example was basically the same as Example 1, and the only difference was that the gradient heating method was replaced by one-step heating pyrolysis. Specifically, it was heated to 900 °C at a heating rate of 3 °C / min and held for two hours.

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

[0067] Comparative Example 4

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

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

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

[0071]

[0072] The above is only used to illustrate the technical solution of the present invention, and the protection scope of the present invention is not limited thereto. Any changes and substitutions that can be easily thought of by those skilled in the relevant fields of this technology within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for preparing an iron-nickel bimetallic carbon-based nanozyme, characterized in that: The steps include: (1) Nickel enrichment: The iron-nitrogen complex is added to a solution containing a nickel-containing complex, stirred at room temperature, filtered, collected, and dried to obtain a nickel-iron precursor; (2) Anchoring of nickel element: The nickel-iron precursor is placed in a tubular furnace and calcined using a gradient temperature increase method under the protection of an inert atmosphere composed of nitrogen and argon to obtain an iron-nickel bimetallic carbon-based nanozyme.

2. The preparation method according to claim 1, characterized in that: In step (1), the iron-nitrogen complex is an iron-containing metal organic framework material, iron phthalocyanine, iron porphyrin or an iron-nitrogen compound made of a nitrogen-containing ligand and an iron salt; the nickel-containing complex is selected from one or more of Ni-EDTA, Ni-IDA, Ni-NTA and Ni-TED.

3. The preparation method according to claim 2, characterized in that: The preparation method of the iron-nitrogen compound made of nitrogen-containing ligand and iron salt is a solvent thermal method, an in-situ synthesis method or a sol-gel method; the wastewater containing the nickel-containing complex is electroplating wastewater.

4. The preparation method according to claim 2, characterized in that In step (1), the nickel content in the solution containing the nickel complex is 5 ppm~30 ppm; in step (2), the gradient temperature calcination is specifically as follows: first, the temperature is increased to 400°C at a heating rate of 2~5°C / min, and the temperature is kept for 0.5~2 h, and then the temperature is continued to be increased to 800~900°C at a heating rate of 2~5°C / min, and the temperature is kept for 1~4 h; the flow rate of the inert gas is 20~50 mL / min.

5. The iron-nickel bimetallic carbon-based nanozyme prepared according to the preparation method described in any one of claims 1 to 4.

6. An iron-nickel bimetallic carbon-based nanozyme electrode, characterized in that: The iron-nickel bimetallic carbon-based nanozyme described in claim 5 is fixed on the electrode surface.

7. The method for preparing the iron-nickel bimetallic carbon-based nanozyme electrode according to claim 6, characterized in that: The following steps are involved: The iron-nickel bimetallic carbon-based nanozyme and 0.5% Nafion solution were evenly dispersed in ethanol by ultrasonic dispersion, and then the dispersed liquid was dropped on the surface of the graphite felt electrode and dried to obtain the iron-nickel bimetallic carbon-based nanozyme / GF electrode.

8. A nanoenzyme fuel cell, characterized in that: It is assembled from the iron-nickel bimetallic carbon-based nanozyme electrode described in claim 6.

9. Use of the nanoenzyme fuel cell according to claim 8 in catalyzing the oxidation of aromatic phenols.

10. The use according to claim 9, characterized in that: The aromatic phenol is 2,4-DCP, PNP or 4-CP.

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