Novel iron-nickel monatomic carbon nanofiber, preparation method thereof and application of novel iron-nickel monatomic carbon nanofiber in portable sensing detection of antibiotics

Abstract

The invention discloses a novel iron-nickel monatomic carbon nanofiber, a preparation method thereof and application of the novel iron-nickel monatomic carbon nanofiber in portable sensing detection of antibiotics. The novel iron-nickel monatomic carbon nanofiber is of a three-dimensional interconnected conductive network structure, a carbon nanofiber is used as a carrier, and iron and nickel monatomic are loaded on the carrier. According to the invention, two metals of iron and nickel are creatively used as templates, physical and chemical methods are comprehensively used, iron elements are uniformly loaded on the surface and inside of foamed nickel, and then the iron-nickel monatomic carbon nanofibers with a three-dimensional interconnected conductive network structure are successfully prepared through an optimized calcination process. Iron and nickel monatomic sites are synchronously anchored in a carbon nanofiber skeleton to form a double-active-center catalytic system.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial preparation technology, specifically to a novel iron-nickel single-atom carbon nanofiber, its preparation method, and its application in portable sensing and detection of antibiotics. Background Technology

[0002] Existing methods for preparing iron-nickel single-atom carbon nanofibers, such as electrospinning combined with pre-oxidation carbonization, can achieve uniform loading of metal single atoms, but still have shortcomings. During preparation, it is difficult to control the uniformity of catalyst dispersion; high-temperature carbonization easily leads to metal particle aggregation, affecting the dispersion of single atoms; spinning parameters and heat treatment conditions require precise control, resulting in complex processes and high costs; product purification requires complex post-treatment to remove impurities; furthermore, some methods have low yields and low efficiency, making it difficult to meet the needs of large-scale applications, and potential issues such as the biotoxicity of the materials when used as electrochemical sensing materials still require further investigation.

[0003] Traditional methods for preparing iron-nickel single-atom carbon nanofibers suffer from several drawbacks: difficulty in controlling catalyst dispersion uniformity; high-temperature carbonization easily leads to metal particle aggregation; precise control of spinning parameters and heat treatment conditions results in complex and costly processes; product purification requires complex post-processing; and low yield and efficiency hinder large-scale application. Therefore, developing a novel method for preparing iron-nickel single-atom carbon nanofibers is urgently needed. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a novel iron-nickel single-atom carbon nanofiber, its preparation method, and its application in portable antibiotic sensing. This invention innovatively selects foamed nickel that has undergone iron ion solution impregnation and cleaning, and utilizes an oscillator or magnetic stirring to enhance the reaction between the two, thereby improving the interaction between the foamed nickel and the active material. Finally, it combines this with melamine powder for high-temperature short-time calcination to optimize the material structure and properties. This series of meticulous and innovative pretreatment steps lays a solid foundation for the subsequent preparation of high-performance materials. Furthermore, it is used as a sensing material to construct an electrochemical sensor for the simultaneous detection of two antibiotics.

[0005] The first objective of this invention is to provide a novel iron-nickel single-atom carbon nanofiber, which is a porous three-dimensional interconnected conductive network structure; using carbon nanofiber as a carrier, the carrier is loaded with iron and nickel single atoms, as well as nitrogen-containing functional groups; The carrier surface contains carbon vacancies, doping sites, or edge defects, which can provide space for the formation of N-containing functional groups (pyridine nitrogen, graphitic nitrogen, amino groups). At the same time, the local electron density changes caused by defects enhance the coordination of nitrogen-containing functional groups with metals (iron and nickel) (such as Ni-N bonds, Fe-N bonds). Furthermore, the high dispersion and stability of iron and nickel single atoms directly stem from the N-containing functional groups regulated by defect engineering. The nitrogen-containing functional group includes one or more of pyridine nitrogen, graphitic nitrogen, and amino groups; The iron and nickel single atoms form coordination interactions with nitrogen-containing functional groups.

[0006] A second objective of this invention is to provide a chip sensor comprising the aforementioned novel iron-nickel single-atom carbon nanofibers. The chip sensor has a multilayer structure, consisting, from top to bottom, a top film, a paper-based microfluidic channel, a screen-printed electrode modified with the novel iron-nickel single-atom carbon nanofibers, and a bottom film. Driven by capillary action, the sample is filtered through an hourglass-shaped inlet and flows along the curved channel to the detection area. The electrochemical signal detected by the sensor is wirelessly transmitted to a mobile phone via Bluetooth.

[0007] A third objective of this invention is to provide a method for preparing the novel iron-nickel single-atom carbon nanofibers, comprising the following steps: A foamed nickel and iron ion solution is provided; The nickel foam is immersed in the iron ion solution, and shaken or stirred to load iron ions on the surface and internal structure of the nickel foam. After drying and washing, it is ready for use. The dried nickel foam was mixed with a nitrogen-containing carbon source and calcined to obtain a composite material. Unstable metal ions in the composite material were removed by using an acid solution. The composite material was then vacuum dried at 50-120℃ to obtain the novel iron-nickel single-atom carbon nanofibers.

[0008] In some embodiments of the present invention, the concentration of the iron ion solution is 0.2-2M.

[0009] In some embodiments of the present invention, the iron salts in the iron ion solution include ferric chloride FeCl3 and / or ferric sulfate Fe2(SO4)3.

[0010] In some embodiments of the present invention, the oscillation time is 20-60 minutes; the stirring time is 1-4 hours; The mass ratio of the dried nickel foam to the nitrogen source is (1:3) to (1:6).

[0011] In some embodiments of the present invention, the nitrogen source is selected from one or more of melamine, urea, dicyandiamide, polypyrrole and polyaniline; the heating and calcination temperature is 700-1000℃ and the time is 5-30 minutes.

[0012] In some embodiments of the present invention, the acid in the acid solution is one or more of hydrochloric acid, sulfuric acid, nitric acid and acetic acid; the concentration of the acid solution is 1-5M; unstable metal ions are removed by stirring at a speed of 200-1500 rpm for 6-24 hours.

[0013] In some embodiments of the present invention, the vacuum drying temperature is 50-120°C.

[0014] In this invention, the synthesis of single-atom catalysts often relies on heating and calcination processes to activate the support, regulate the metal coordination environment, and enhance the metal-support interaction. However, long durations can lead to metal agglomeration. Therefore, it is necessary to control the conditions well. Alternatively, ultrafast heating technology (such as Joule heating) can be used to replace it, achieving more efficient and precise single-atom preparation.

[0015] A third objective of this invention is to provide the application of the novel iron-nickel single-atom carbon nanofibers or the chip sensor in the detection of antibiotics.

[0016] In some embodiments of the present invention, the antibiotics include chloramphenicol and nitrofurantoin.

[0017] In some embodiments of the present invention, the concentration of the novel iron-nickel single-atom carbon nanofibers is 1 mg / mL to 10 mg / mL.

[0018] In some embodiments of the present invention, the concentration of the antibiotic is 3 nM to 2.4 mM of nitrofurantoin and 100 nM to 2.1 mM of chloramphenicol.

[0019] In this invention, novel iron-nickel dual-single-atom carbon nanofibers serve as electrochemical sensing materials, achieving highly sensitive and interference-resistant detection of nitrofurantoin and chloramphenicol due to their unique structural advantages. In this composite material, Fe and Ni single atoms are atomically dispersed on the surface of the carbon nanofibers, forming Fe-N and Ni-N coordination structures, which serve as active centers for nitro reduction, lowering the reaction energy barrier through synergistic catalysis. The three-dimensional network structure of the carbon nanofibers provides high conductivity, accelerating electron transfer, while their porous nature promotes the diffusion of antibiotic molecules to the active sites, enhancing mass transfer efficiency. Under the catalysis of iron-nickel single atoms, the nitro group in the nitrofurantoin molecule undergoes a multi-step reduction to generate an amino group, producing a significant reduction peak current. The nitro group in chloramphenicol undergoes a similar reduction reaction under the action of iron-nickel single atoms, but due to the different structures of the antibiotics and the differences in the d-orbital electronic configurations of Fe and Ni, their reduction potentials differ, achieving signal separation. Furthermore, the furan ring of nitrofurantoin and the benzene ring of chloramphenicol exhibit different adsorption orientations on the electrode surface, further enhancing selectivity. The detection limits of this material for both antibiotics are in the nM range.

[0020] The beneficial effects of this invention are: The preparation method of this invention has a simple operation process and low cost, exhibiting significant economic advantages. Furthermore, the electrode modified with iron-nickel single-atom carbon nanofibers not only demonstrates excellent catalytic effects on chloramphenicol and nitrofurantoin, but also exhibits outstanding anti-interference capabilities. Further, combining this iron-nickel single-atom carbon nanofiber-modified screen-printed electrode with a paper-based microfluidic chip designed with an hourglass shape allows for direct detection of raw samples (such as lake water samples) without complex pretreatment. Compared with traditional sensors, the sensor constructed based on iron-nickel composite materials is simpler in structure and operation, significantly more economical, and greatly enhanced in practicality. Therefore, in the field of environmental monitoring, this sensor undoubtedly has a broader industrialization prospect and is expected to bring about new changes and breakthroughs in related detection work.

[0021] This invention innovatively uses iron and nickel as templates, employing a combination of physical and chemical methods to uniformly load iron onto the surface and interior of nickel foam. Subsequently, through an optimized calcination process, iron-nickel single-atom carbon nanofibers with a three-dimensional interconnected conductive network structure are successfully prepared. Iron and nickel single-atom sites are simultaneously anchored within the carbon nanofiber framework, forming a dual-active-center catalytic system. Compared to traditional preparation methods, the iron-nickel single-atom carbon nanofibers of this invention overcome the limitations of existing technologies, such as metal agglomeration, limited functionality, and high cost, through bimetallic synergistic coordination, a three-dimensional interconnected conductive network, and defect-engineered active site design. Their unique microstructure exhibits significant advantages in the field of multifunctional electrochemical sensing.

[0022] This invention relates to a sensor constructed using screen-printed electrodes modified with iron-nickel single-atom carbon nanofibers. This sensor exhibits exceptionally high sensitivity and selectivity in the detection of chloramphenicol and nitrofurantoin. The application prospects of these iron-nickel single-atom carbon nanofibers are vast. They can be directly applied to numerous fields, and their catalytic performance can be further optimized in various fields such as biosensing, catalysis, and energy by loading specific catalysts such as noble metals, oxides, and sulfides, providing strong material support for technological innovation in these areas. Attached Figure Description

[0023] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 These are scanning electron microscope (SEM) images and aberration electron microscope (SEM) images of the iron-nickel single-atom carbon nanofibers of the present invention.

[0024] Figure 2The figures show the cyclic voltammetry (CV) test results of the composite materials obtained in the embodiments and Comparative Example 1 of this invention; wherein, Figure A is the CV diagram of different materials for 1mM nitrofurantoin, Figure B is the reduction peak current bar graph corresponding to Figure A, Figure C is the CV diagram of different materials for 1mM chloramphenicol, and Figure D is the reduction peak current bar graph corresponding to Figure C; the Bare group is an electrode without iron and nickel.

[0025] Figure 3 This invention presents anti-interference detection diagrams and response diagrams at different concentrations of the sensor prepared from iron-nickel single-atom carbon nanofibers for the detection of nitrofurantoin (A, C) and chloramphenicol (B, D).

[0026] Figure 4 This invention is a portable real-time detection chip that integrates a paper-based microfluidic chip with an hourglass-shaped filtration system with a screen-printed electrode modified with iron-nickel single-atom carbon nanofibers. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0028] Example 1: This embodiment provides a novel method for preparing iron-nickel single-atom carbon nanofibers, as detailed below: (1) Pretreatment of nickel foam: First, the nickel foam is precisely cut to a size of 1cm × 1cm × 1mm. Then, through a polishing process, burrs and oxide scale are carefully removed from its surface, which not only significantly improves the surface smoothness but also enhances its adhesion to subsequent additives.

[0029] Next, perform chemical cleaning: use 1M hydrochloric acid to react with the oxide layer, dissolving and removing it. Then, use 5% sodium hydroxide solution to thoroughly remove the oil stains for 10 minutes. After acid and alkali cleaning, rinse five times with deionized water to ensure that there are no residual chemicals on the surface of the foamed nickel.

[0030] Next, the nickel foam is placed in an ultrasonic cleaning device to further remove fine impurities from the surface, achieving deep cleaning. After ultrasonic cleaning, the nickel foam is placed in an oven set at 60°C and dried for 4 hours to completely remove moisture.

[0031] (2) Preparation of iron-nickel single-atom carbon nanofibers: S1. Prepare a 1M iron ion solution using ferric chloride (FeCl3). Immerse the pre-treated nickel foam in the iron ion solution and shake for 30 minutes to ensure sufficient contact and reaction between the nickel foam and the iron ion solution, allowing iron ions to be loaded onto the surface and internal structure of the nickel foam. After stirring, wash the nickel foam with 0.2M hydrochloric acid to remove any unreacted residues on the surface, and then dry it again at 60°C for 1 hour.

[0032] S2. 1g of dried nickel foam and 6g of melamine powder were uniformly mixed and calcined in a tube furnace at 900℃ for 5 minutes to obtain the composite material Fe1Ni-NC. The calcined composite material was then stirred in a 2M hydrochloric acid solution at 600 rpm for 15 hours to remove unstable metal ions. Finally, it was dried in a vacuum drying oven at 60℃ to obtain iron-nickel single-atom carbon nanofibers. The structure of the obtained novel iron-nickel single-atom carbon nanofibers was characterized, and the results are as follows. Figure 1 As shown, by Figure 1 Scanning electron microscopy (SEM) images revealed tubular and tortuous carbon microstructures with a diameter of approximately 200 nanometers. Further elemental distribution analysis using energy dispersive spectroscopy (EDS) showed that C, N, Fe, and Ni were uniformly distributed in the sample.

[0033] Example 2 The preparation method of nickel single-atom carbon nanofibers provided in this embodiment is the same as that in Example 1, the difference being that in step (2), the iron ion solution concentration is 0.5M. The final composite material Fe is obtained. 0.5 Ni-NC.

[0034] Example 3 The preparation method of nickel single-atom carbon nanofibers provided in this embodiment is the same as that in Example 1, the difference being that in step (2), the iron ion solution concentration is 1.5M. The final composite material Fe is obtained. 1.5 Ni-NC.

[0035] Comparative Example 1 The preparation method of the nickel single-atom carbon nanofibers provided in this comparative example is the same as that in Example 1, except that in step (2), iron ion solution was not used for soaking. The final composite material Ni-NC was obtained.

[0036] The composite materials obtained in Examples 1-3 and the composite material obtained in Comparative Example 1 were subjected to cyclic voltammetry tests, and the results are as follows: Figure 2 As shown in the figure, the current response signal is strongest when the iron ion concentration is 1M (Fe1Ni-NC) for testing nitrofurantoin (NFT) and chloramphenicol (CAP).

[0037] Specificity test: To evaluate the potential application value of this sensor chip in practical sample analysis, its specificity was investigated. Interfering agents, including inorganic ions (such as potassium, sodium, and chloride ions) and other antibiotics (such as ampicillin trihydrate (AMP), ciprofloxacin (CIP), amoxicillin (AMX), kanamycin (KAN), and tetracycline (TC)), were tested to examine the sensor's selectivity. The concentrations of NFT and CAP were fixed at 1 mM, and various interfering agents at concentrations of 5 mM (five times the target concentration) were also investigated. Figure 3 As shown in A and B, NFT ( Figure 3 (A) and CAP Figure 2 (B) showed a distinct characteristic reduction peak, while all interfering substances showed almost no current response. These results clearly demonstrate that the electrochemical sensor constructed based on iron-nickel single-atom carbon nanofibers has high selectivity and can be used to monitor the antibiotic content of NFTs and CAPs in real samples.

[0038] Application examples To assess its potential practical application value, an electrochemical sensing chip was constructed based on iron-nickel single-atom carbon nanofibers and combined with a paper-based microfluidic device, and used for on-site detection of antibiotics in lake water samples. For example... Figure 4 As shown, the sensor has a multilayer structure, comprising, from top to bottom, a top film, a paper microfluidic channel, a screen-printed electrode modified with iron-nickel single-atom carbon nanofibers, and a bottom film. Driven by capillary forces, the sample is filtered through an hourglass-shaped paper inlet and flows along the curved channel to the detection area. The electrochemical signal detected by the sensor is wirelessly transmitted to a mobile phone via Bluetooth. Figure 4 The display shows that when the sensor chip directly detects lake water samples, the detection signal can be displayed on the mobile phone screen in real time.

[0039] The embodiments described above are merely preferred embodiments for fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A novel iron-nickel single-atom carbon nanofiber, characterized in that, It is a porous three-dimensional interconnected conductive network structure; carbon nanofibers are used as a carrier, and iron and nickel single atoms, as well as nitrogen-containing functional groups are loaded on the carrier; The surface of the carrier contains carbon vacancies, doping sites, or edge defects; The functional groups include one or more of pyridine nitrogen, graphitic nitrogen, and amino groups; The iron and nickel single atoms form coordination interactions with nitrogen-containing functional groups.

2. A chip sensor, characterized in that, Including the novel iron-nickel single-atom carbon nanofibers as described in claim 1.

3. A method for preparing the novel iron-nickel single-atom carbon nanofibers as described in claim 1, characterized in that, Includes the following steps: A foamed nickel and iron ion solution is provided; The nickel foam is immersed in the iron ion solution, and shaken or stirred to load iron ions on the surface and internal structure of the nickel foam. After drying and washing, it is ready for use. The dried nickel foam was mixed with a nitrogen-containing carbon source and calcined to obtain a composite material. Unstable metal ions in the composite material were removed by using an acid solution. The composite material was then vacuum dried at 50-120℃ to obtain the novel iron-nickel single-atom carbon nanofibers.

4. The preparation method according to claim 3, characterized in that, The concentration of the ferric ion solution is 0.2-2M; the ferric salts in the ferric ion solution include ferric chloride FeCl3 and / or ferric sulfate Fe2(SO4)3.

5. The preparation method according to claim 3, characterized in that, Shaking time is 20-60 minutes; stirring time is 1-4 hours; The mass ratio of the dried nickel foam to the nitrogen-containing carbon source is (1:3) to (1:6).

6. The preparation method according to claim 3, characterized in that, The nitrogen source is selected from one or more of melamine, urea, dicyandiamide, polypyrrole, and polyaniline; the heating and calcination temperature is 700-1000℃, and the time is 5-30 minutes.

7. The preparation method according to claim 3, characterized in that, The acid in the acid solution is one or more of hydrochloric acid, sulfuric acid, nitric acid, and acetic acid; the concentration of the acid solution is 1-5M; unstable metal ions are removed by stirring at a speed of 200-1500 rpm for 6-24 hours.

8. The preparation method according to claim 3, characterized in that, The temperature for vacuum drying is 50-120℃.

9. The application of the novel iron-nickel single-atom carbon nanofiber of claim 1 or the chip sensor of claim 2 in the detection of antibiotics.

10. The application as described in claim 9, characterized in that, The antibiotics include chloramphenicol and nitrofurantoin.

Images