CN113277499A

CN113277499A - Preparation method and application of silicon-nitrogen co-doped graphene quantum dot

Info

Publication number: CN113277499A
Application number: CN202110497881.2A
Authority: CN
Inventors: 吴一微; 高军; 占鑫; 黄小斌; 黎本梦杨
Original assignee: Excellent Color Technology Hubei Co ltd; Hubei Normal University
Current assignee: Excellent Color Technology Hubei Co ltd; Hubei Normal University
Priority date: 2021-05-07
Filing date: 2021-05-07
Publication date: 2021-08-20
Anticipated expiration: 2041-05-07
Also published as: CN113277499B

Abstract

The invention relates to the technical field of quantum dot preparation, in particular to a preparation method and application of silicon-nitrogen co-doped graphene quantum dots based on waste carbon powder. The method takes the resin in the waste carbon powder as a carbon source, synthesizes the nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) by a one-pot hydrothermal method, is simpler in synthesis method and safe to operate, and the obtained quantum dots have obvious bactericidal effect on bacillus subtilis and escherichia coli. According to the method, the waste carbon powder is used as a carbon source to prepare the nitrogen-silicon co-doped graphene quantum dots, so that the waste carbon powder generated in the production process of a printer/copier is reasonably utilized, the waste treatment cost is reduced, the production cost of the graphene quantum dots is reduced, and compared with the production method recorded in the existing literature, the method for producing 1 ton of graphene quantum dots does not need to use citric acid, and the cost can be reduced by 3 times.

Description

Preparation method and application of silicon-nitrogen co-doped graphene quantum dot

Technical Field

The invention relates to the technical field of quantum dot preparation, in particular to a synthetic preparation method and application of silicon-nitrogen co-doped graphene quantum dots based on waste carbon powder.

Background

With the development of printing and copying technology and the requirement of paper office, more and more waste carbon powder is generated. At present, the disposal of the waste carbon powder does not draw enough attention, and most of the waste carbon powder is disposed along with the incineration or landfill of the garbage. However, the resin in the waste carbon powder is not easy to degrade, and the waste carbon powder has extremely small and light particles and is insoluble in water, so that the problem of serious environmental pollution is caused. In order to promote the development of green economy and comprehensively improve the resource utilization rate, the research on a new solid waste treatment method and a new recycling technology of waste carbon powder is not slow.

In addition, in recent years, contamination with microorganisms (including bacteria, fungi, yeasts, viruses, and the like) and pathogenic bacteria has become a serious problem of global concern, and has a serious influence on the health and safety of human beings, and microbial infection by pathogenic microorganisms occurs in various environments. The graphene materials show great potential in various fields due to unique physical and chemical structures, and the unique action mode of the graphene materials and microorganisms enables the graphene materials to be completely exposed in the antibacterial field. As the variety and the number of antibacterial products are continuously increased and the drug resistance of microorganisms is continuously enhanced, the requirements on antibacterial agents are also higher and higher. The graphene quantum dots inherit a plurality of advantages of graphene as a novel carbon-based nano material and are widely applied to a plurality of fields such as materials, energy, medicine, biology and the like, so that the development of a graphene antibacterial agent and the reduction of the production cost thereof are of great significance.

Disclosure of Invention

Aiming at the technical problems in the prior art, one of the purposes of the invention is to provide a silicon-nitrogen co-doped graphene quantum dot, wherein the graphene quantum dot is prepared from waste carbon powder and ethylenediamine, the maximum ultraviolet absorption wavelength of the graphene quantum dot is 280-350 nm, blue fluorescence is emitted by an ultraviolet lamp, and in the preparation process, the carbon powder is a precursor and the Ethylenediamine (EDA) is a reducing agent.

The invention also aims to provide a preparation method of the silicon-nitrogen co-doped graphene quantum dot, which comprises the following steps: dissolving waste carbon powder and ethylenediamine in water according to the mass ratio of 5 (9-45), reacting at 160-200 ℃ for 2-16 h, and filtering to obtain the catalyst.

Wherein the mass ratio of the waste carbon powder to the ethylenediamine is 5 (18-36); preferably, the mass ratio of carbon powder to ethylenediamine is 5: 27.

Wherein the mass percent of the waste carbon powder in the total reaction system is 1.5-2%.

The carbon powder adopted in the invention is waste carbon powder of a printer.

Wherein the reaction time is 4-16 h when the reaction temperature is 160 ℃; preferably, the reaction time is 8-16 h when the reaction temperature is 160 ℃.

Wherein the reaction temperature is 180 ℃, and the reaction time is 4-16 h; preferably, the reaction temperature is 180 ℃ and the reaction time is 6-12 h.

Wherein the reaction temperature is 200 ℃, and the reaction time is 4-16 h; preferably, the reaction temperature is 200 ℃, and the reaction time is 4-8 h; preferably, the reaction temperature is 200 ℃ and the reaction time is 4 h.

The third purpose of the invention is to provide the application of the silicon nitrogen co-doped graphene quantum dot in the antibacterial aspect; preferably, the bacteria are Escherichia coli and Bacillus subtilis.

Wherein the minimum bactericidal concentration in the anti-Escherichia coli application is 2.16 × 10^-4g/mL。

The method utilizes waste carbon powder of a printer to synthesize nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs), and adopts a bottom-up method to synthesize the nitrogen and silicon co-doped graphene quantum dots. The method takes resin in waste carbon powder as a carbon source, and adopts a one-pot hydrothermal method to synthesize the nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) in an environmentally-friendly manner. Meanwhile, Ethylenediamine (EDA) is used as a reducing agent, silicon dioxide in a waste carbon powder additive is used as a silicon source, synthesized nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) have uniform particle size, the size of about 1.5nm, abundant N, O atoms on the surface, abundant electrons, excellent water solubility and good fluorescence property, the maximum excitation and emission wavelengths are 320nm and 385nm respectively, the stability is good, the quantum dots can be widely applied to photoelectric devices, fluorescent probes, biological imaging and the like, the inventor also finds that the quantum dots can be used for antibiosis, especially for resisting escherichia coli, compared with a hydrothermal precursor (R.Qu, M.ZHENG, L.Zhang, H.ZHao, Z.Xie, X.Jing, R.E.Haddad, H.Fan, Z.Sun, Formation catalysis and optimization of growth N-doped graphene precursors, a crystal precursor 5294, a one-step citric acid comparison method, the material has obvious bactericidal effect on escherichia coli and bacillus subtilis and has greater potential in the fields of chemical analysis and medical biological application.

According to the method, the waste carbon powder is used as a carbon source to prepare the nitrogen-silicon co-doped graphene quantum dots, so that the waste carbon powder generated in the production process of the printer is reasonably utilized, the waste treatment cost is reduced, and the production cost of the graphene quantum dots is reduced.

Drawings

FIG. 1 is a synthesis flow chart of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs);

FIG. 2 is a TEM (transmission electron microscope) representation diagram of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs);

FIG. 3 is an XRD (X-ray diffraction) characterization diagram of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs);

fig. 4 is a XPS representation of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs), wherein (a) is a full spectrum scan XPS representation, (b) is a carbon spectrum scan XPS representation, (c) is an oxygen spectrum scan XPS representation, (d) is a nitrogen spectrum scan XPS representation, and (e) is a silicon spectrum scan XPS representation;

FIG. 5 is an iron spectrum scanning XPS characterization graph of G carbon powder and nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs), wherein (a) is the G carbon powder iron spectrum scanning XPS characterization graph, and (b) is the nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) iron spectrum scanning XPS characterization graph;

FIG. 6 is a VSM (voltage source/drain) representation diagram of G carbon powder and nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs), wherein (a) is the VSM representation diagram of G carbon powder and (b) is the VSM representation diagram of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs);

fig. 7 is a thermogravimetric analysis characterization diagram of G carbon powder and nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) under an oxygen condition, wherein (a) is the thermogravimetric analysis characterization diagram of G carbon powder under the oxygen condition, and (b) is the thermogravimetric analysis characterization diagram of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) under the oxygen condition;

FIG. 8 is an infrared characterization diagram of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs);

FIG. 9 is a graph of ultraviolet spectrum and fluorescence spectrum of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs);

FIG. 10 is a Zeta potential contrast diagram of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) synthesized by A-I carbon powder

FIG. 11 is a comparison graph of colonies on MH plates with different concentrations of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs), wherein (a) is 0g/mL, and (b) is 1.54 × 10^-4g/mL，(c)1.85×10^-4g/mL，(d)2.16×10^-4g/mL，(e)2.47×10^-4g/mL，(f)2.78×10^-4g/mL，(g)3.09×10^-4g/mL；

FIG. 12 is a comparison graph of the colony conditions on MH plates at different sterilization treatment times for nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs), wherein (a) is 2.16 × 10 for nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs)^-4g/mL, E.coli stock dilution 10^-1Double, flat chart when sterilizing for 0 h; (b) is a nitrogen and silicon co-doped stoneGraphene quantum dots (N, Si-GQDs)2.16 x 10^-4g/mL, E.coli stock dilution 10^-4Double, flat chart when sterilizing for 0 h; (c) is nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs)2.16 multiplied by 10^-4g/mL, E.coli stock dilution 10^-4Double, flat chart when sterilizing for 0.5 h; (d) is nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs)2.16 multiplied by 10^-4g/mL, E.coli stock dilution 10^-4Double, plate diagram after 1h of sterilization; (e) is nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs)2.16 multiplied by 10^-4g/mL, E.coli stock dilution 10^-4Double, flat chart when sterilizing for 1.5 h; (f) is nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs)2.16 multiplied by 10^-4g/mL, E.coli stock dilution 10^-4Double, flat chart when sterilizing for 2 h;

fig. 13 is a comparison graph of the bactericidal effect of the graphene quantum dot bacillus subtilis synthesized by the literature method and the method, wherein (a) is a graph of the bactericidal effect of the graphene quantum dot bacillus subtilis synthesized by the method, and (b) is a graph of the bactericidal effect of the bacillus subtilis of the quantum dot synthesized by the literature method.

Detailed Description

The present invention is further described in detail below with reference to specific examples so that those skilled in the art can more clearly understand the present invention.

The following examples are provided only for illustrating the present invention and are not intended to limit the scope of the present invention. All other embodiments obtained by a person skilled in the art based on the specific embodiments of the present invention without any inventive step are within the scope of the present invention.

The raw material sources are as follows: the following examples relate to raw material sources as shown in table 1 below, wherein the waste carbon powders a to G are provided by the excel technology ltd, wherein the waste carbon powder G is collected on site by a dust collector in a production plant, the components of the waste carbon powder are from the substances in the waste carbon powders a to F, but the specific contents are unknown, and H and I are printer waste carbon powders of any 2 brands selected in the market, and the components and the contents are also unknown.

TABLE 1 composition information of different types of waste carbon powders

Example 1

The embodiment provides a synthesis method of silicon nitrogen co-doped graphene quantum dots (N, Si-GQDs), which mainly comprises the following steps:

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 160 ℃ for 4 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 2

0.1G of G carbon powder was weighed, and 1000. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:45) and 5mL deionized water are mixed in a 25mL hydrothermal reaction kettle, reacted in an air-blast drying oven at 160 ℃ for 4 hours, and after the reaction is finished, filtered by a 0.22 μm aqueous filter tip, and a yellow liquid is reserved and stored at 4 ℃ for later use.

Example 3

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 160 ℃ for 16 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 4

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL of deionized water were mixed in 25mL of hydrothermal reactionReacting in a kettle at 160 ℃ in an air-blast drying oven for 12h, filtering by a 0.22 mu m aqueous filter head after the reaction is finished, reserving yellow liquid, and storing at 4 ℃ for later use.

Example 5

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 160 ℃ for 8 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 6

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 160 ℃ for 6 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 7

Example 8

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in a 160 ℃ forced air drying oven for 2 hoursAfter the completion of the reaction, the mixture was filtered through a 0.22 μm aqueous filter, and the yellow liquid was retained and stored at 4 ℃ for further use.

Example 9

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 180 ℃ for 8 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 10

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 180 ℃ for 16 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 11

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 180 ℃ for 12 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 12

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water are mixed in a 25mL hydrothermal reaction kettle, reacted for 6h in a 180 ℃ air-blast drying oven, and filtered by a 0.22 mu m water-based filter head after the reaction is finished, and the mixture is retainedYellow liquid, stored at 4 ℃ for use.

Example 13

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 180 ℃ for 4 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 14

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 180 ℃ for 2 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 15

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 200 ℃ for 2 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 16

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 200 ℃ for 4 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 17

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 200 ℃ for 6 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 18

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 200 ℃ for 8 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 19

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 200 ℃ for 12 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 20

0.1G of G carbon powder was weighed, and 600. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:27) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 200 ℃ for 16 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 21

0.1G of G carbon powder was weighed, and 200. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:9) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 160 ℃ for 4 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 22

0.1G of G carbon powder was weighed, and 400. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:18) and 5mL deionized water are mixed in a 25mL hydrothermal reaction kettle, reacted in an air-blast drying oven at 160 ℃ for 4 hours, and after the reaction is finished, filtered by a 0.22 μm aqueous filter tip, and a yellow liquid is reserved and stored at 4 ℃ for later use.

Example 23

0.1G of G carbon powder was weighed, and 800. mu.L of ethylenediamine (m) was added_{Carbon powder}：m_{Ethylene diamine}No. 5:36) and 5mL deionized water were mixed in a 25mL hydrothermal reaction kettle, and reacted in an air-blown dry oven at 160 ℃ for 4 hours, after the reaction was completed, the mixture was filtered through a 0.22 μm aqueous filter, and a yellow liquid was retained and stored at 4 ℃ for further use.

Example 24

The embodiment provides a synthesis method of silicon nitrogen co-doped graphene quantum dots (N, Si-GQDs), specifically, different types of waste carbon powder are used as carbon source precursors of the graphene quantum dots for preparation, the content composition of the waste carbon powder is shown in table 1, and the specific preparation steps are as follows:

a, B, C, D, E, F, G, H, I carbon powders 0.1g are weighed respectively, and then 400 μ L of ethylenediamine (mass ratio m of carbon powders to ethylenediamine) is added_{Carbon powder}：m_{Ethylene diamine}No. 5:18) and 5mL deionized ultrapure water are put into a 25mL hydrothermal reaction kettle and reacted for 4h in a forced air drying oven at 160 ℃,after the reaction, the mixture was filtered through a 0.22 μm aqueous filter, and the yellow liquid was retained and stored at 4 ℃ for further use.

And (4) analyzing results:

(1) the products obtained in examples 1 to 24 were characterized by UV-vis absorption spectrum, fluorescence spectrum, FTIR spectrum, Transmission Electron Microscope (TEM), zeta potential, X-ray electron spectrum (XPS), X-ray diffraction (XRD), simultaneous thermal analysis, etc., respectively, and they were similar or identical to the following results:

the TEM and XRD characterization results are shown in FIGS. 2 and 3: from FIG. 2, it can be seen that the lattice fringe spacing is 0.236nm, similar to the graphite 1120 level; from FIG. 2, it can also be seen that the average particle size is 1.5. + -. 0.25 nm; the XRD in fig. 3 is characterized by 2 θ of 27.351 ° which is close to the 002 plane of graphite, demonstrating that the material is graphite-like carbon.

The surface chemical composition of the material was characterized by XPS as shown in fig. 4 and 5: from the results of XPS spectroscopy (fig. 4a) it is clear that the material contains N1 s, Si 2p in addition to graphite C1 s, O1 s. Comparing the Fe 2p map of the G carbon powder before synthesis in FIG. 5(a) with the Fe 2p map of the material after synthesis in FIG. 5(b), the obvious disappearance of the characteristic peak of Fe 2p is known; fig. 6(a) and 6(b) are hysteresis gyrogram (VSM) detection results of G carbon powder and the material, respectively, and a comparison result shows that the synthesized material is not doped with Fe. Fig. 4(b) C1 s 287.35eV,284.8eV,285.02eV,284.14eV,283.52eV are C ═ O, C-C/C ═ C, C-N, C-Si, Organic-C (graphene), respectively; FIG. 4(C) O1 s:532.22eV,531.66eV is C-O-C, respectively, and C ═ O; FIG. 4(d) N1 s 400.07eV 406.9eV 401.56eV are respectively N-C (graphene), nitrate, N-H; FIG. 4(e) Si 2p 101.9eV and 102.96eV are respectively Organic-Si and Si-C. The material is further proved to be nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs).

The FTIR infrared characterization results are shown in FIG. 8: from FTIR infrared characterization in FIG. 8, it can be known that the structure of the nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) contains O-Si (979 cm)^-1),C-O-C(1010cm^-1) C-H (2960/2920 cm) in an aromatic ring^-1),O-H/N-H(3430cm^-1)；1350cm^-1The following are C-C/C-H (1150 cm)^-1) The expansion vibration absorption peak (G carbon powder which is not completely carbonized) graphene oxide quantum dot has no C-H bond absorption, which shows thatG, completely carbonizing carbon powder; wherein 704cm^-1Is the stretching vibration absorption peak of the secondary amine; C-N (1400 cm)^-1) And C ═ O (1630 cm) of C ═ O-NH^-1) And the peak is an aromatic ring skeleton vibration absorption peak (no aromatic ring skeleton vibration exists in the carbon dots and the graphene oxide quantum dots).

The thermogravimetric analysis results of the synthetic material and the G waste carbon powder are shown in fig. 7: as can be seen from the DTA curve, in FIG. 7(a), volatilization of water and residual reactant ethylenediamine may occur at a temperature of 100 ℃ or lower; in FIG. 7(b), the temperature below 100 ℃ is the evaporation of water in the sample; (a) the weight loss at 600 ℃ is about 80% at the end, and the residue may be nitrate or iron oxide, and (b) the weight loss at 450 ℃ is about 60% at the end, and the residue may be iron oxide or a small amount of silica. Therefore, the combination of XPS analysis can prove that the silicon dioxide participates in the synthesis of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs). FIG. 10 shows Zeta potential measurements of various types of carbon powders, which indicate that the particle surface is negatively charged.

The nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) have excellent water solubility, the solution is light yellow under visible light, and blue fluorescence is emitted under an ultraviolet lamp (figure 9 inset). The graphene quantum dot emission spectrum generally has two peaks corresponding to an eigenstate excitation in a high energy state and a defect state excitation in a low energy state. 2 absorption peaks can be seen from an ultraviolet absorption spectrum (red line), and a sharp absorption peak with pi-pi transition exists at a position of 280nm-300 nm; the absorption peak at 300nm-325nm is n-pi transition. From the fluorescence spectrum of FIG. 9, it is found that the optimum excitation wavelength is 320nm and the optimum emission wavelength is 385 nm. To date, there are two generally accepted mechanisms of light emission for graphene quantum dots: intrinsic state emission (determined by the graphene core) and defect state emission (controlled by external functional groups). Quantum confinement effect, edge effect and sp²Photoluminescence corresponding to carbon domain electron-hole recombination is called eigenstate emission; photoluminescence corresponding to surface defects (energy traps) is called surface defect state emission. Therefore, the fluorescence characteristics of the nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) are probably caused by the reasons.

Quantum yield and fluorescence lifetime of the materials obtained under each of the conditions in examples 1 to 23Detection analysis was performed, wherein the reaction conditions and detection results in examples 1 to 23 are shown in table 2 below, and the quantum yield and fluorescence lifetime data of the material obtained in example 24 are shown in table 3 below, wherein an F-4700 fluorescence spectrometer was used for detecting the fluorescence intensity, an FLS 980 time-resolved spectrometer was used for detecting the fluorescence lifetime, and the detection and calculation methods of the quantum yield were as follows: selecting quinine sulfate with known fluorescence quantum yield as a reference substance according to the ultraviolet maximum absorption wavelength of 320nm and the fluorescence emission wavelength of 385nm, wherein the fluorescence quantum yield of the reference substance is 0.54. The UV absorbance (typically at absorbance A) of the target compound and the reference phosphor in the same solvent (aqueous solution) are measured separately<0.05) and relative fluorescence intensity, and integrating the fluorescence peaks respectively to obtain integral fluorescence intensity. And substituting the obtained parameters into a formula to calculate the relative fluorescence quantum yield of the object to be detected. See quantum yield calculation equation

Wherein

Is the fluorescence quantum yield of the object to be detected,

the fluorescence quantum yield of the reference substance Is shown, Iu Is the integral fluorescence intensity of the reference substance, Is the integral fluorescence intensity of the reference substance, Au Is the absorbance of the reference substance, and As Is the absorbance of the reference substance.

TABLE 2 Quantum yields and fluorescence lifetimes of luminescent materials prepared in examples 1 to 14

TABLE 3 Quantum yield and fluorescence lifetime of the luminescent materials prepared

As can be seen from table 3: the synthesis method has universality and has no special requirements on the type, model, component, content and the like of the waste carbon powder; the quantum yield of the luminescent material prepared from No. A carbon powder, No. E carbon powder, No. F carbon powder and No. G waste carbon powder is superior to that of other carbon powder, and the No. G carbon powder can simulate various carbon powder collected in the market in terms of components and is more representative.

Application examples

Experiments are further carried out on the application of the prepared nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs), the prepared graphene quantum dots (N, Si-GQDs) are respectively used in antibacterial researches of bacillus subtilis, escherichia coli and staphylococcus aureus, and the results show that the quantum dots (N, Si-GQDs) have antibacterial effects on both bacillus subtilis and escherichia coli and have no effect on staphylococcus aureus. The antibacterial effect of the prepared graphene quantum dots (N, Si-GQDs) on escherichia coli is further compared with the antibacterial effect of antibiotic ampicillin on escherichia coli, and the result shows that the antibacterial effect is 2.16 multiplied by 10^-4The antibacterial effect of 160 ten thousand units of ampicillin is equivalent to that of g/mL of the quantum dot.

The antibacterial effect of the prepared nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) on escherichia coli and bacillus subtilis is further researched, and the specific steps and results are as follows:

(1) preparing an escherichia coli mother liquor: according to the requirement of aseptic operation, a single Escherichia coli colony is picked by an inoculating loop, inoculated into 10mL of liquid agar medium, incubated in a constant temperature oscillator at 37 ℃ for 24h, and stored as mother liquor at 4 ℃ for standby. Preparing escherichia coli bacterial solutions with different concentrations by adopting a stepwise dilution method: preparing 5 sterile test tubes with the numbers of A, B, C, D respectively, and adding 900 mu L of physiological saline respectively; taking 100 mu L of escherichia coli bacterial mother liquorAfter mixing in tube A, 100. mu.L of the mixture was taken out from tube A and diluted in tube B, and then diluted to tube D. Final A, B, C, D dilution of bacterial mother liquor 10^-1、10^-2、10^-3、10^-4Double E.coli solution.

(2) Coli minimum bactericidal concentration test: respectively transferring the D test tubes to dilute 10^-4100 mu L of colibacillus solution is put in 7 aseptic test tubes and numbered as (r) -c. The test tubes are added with N, Si-GQDs synthesized by the carbon powder G in the example 17: 0. mu.L, 50. mu.L, 60. mu.L, 70. mu.L, 80. mu.L, 90. mu.L, 100. mu.L; then, 900. mu.L, 850. mu.L, 840. mu.L, 830. mu.L, 820. mu.L, 810. mu.L and 800. mu.L of physiological saline were added thereto, respectively. Finally, 100. mu.L of Escherichia coli liquid in test tubes were applied to Mueller-Hinton agar basal medium (MH medium) plates, and cultured at 37 ℃ for 24 hours, each tube was made 3 times in parallel, and the results are shown in FIG. 11, and it can be seen from FIG. 11 that when 10 dilutions were removed^-4When 100 muL of the escherichia coli bacteria mother liquor is multiplied, 70 muL of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) is added to reach a sterilization threshold, and the minimum sterilization concentration of the nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) is as follows: 2.16X 10^-4g/mL。

(3) The sterilization time of the escherichia coli is optimized by respectively transferring the bacterium mother liquor and diluting the bacterium mother liquor in a C test tube by 10 percent^-3Duplicate E.coli solutions, 100. mu.L, were placed in 2 sterile test tubes, numbered E, F, respectively. After 70. mu.L of N, Si-GQDs synthesized in example 17 were sequentially added to E, F test tubes, 830. mu.L of physiological saline was added thereto. Finally E, F E.coli liquid in test tube was diluted 10 times respectively^-1And 10^-4And (4) doubling. Adding 50 mu L of the bacterial liquid in the bacterium E into a test tube No. I, culturing for 0h at 37 ℃, adding 50 mu L of the bacterial liquid in the bacterium F into a test tube No. II to No. III, and culturing for 0h, 0.5h, 1.5h and 2.0h at 37 ℃. Finally, 50 μ L of the bacterial solution in the test tube (I-II) was spread on MH medium plates, and each tube was performed 3 times in parallel, and the results are shown in FIG. 12. As can be seen from FIG. 12, when the concentration of nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) was 2.16X 10-4g/mL, a was diluted 10^-1Multiplied Escherichia coli bacterial liquid, b is diluted 10^-4The bacterial liquid of the escherichia coli of (a),the culture time of a and b is 0 h; b-f are dilutions 10^-4The results of the graph show that 0.5h almost completely kills escherichia coli, and meanwhile, only one colony grows on a plate with the culture time of 0.5 h. In conclusion, the optimal sterilization time is 0.5 h.

(4) Compared with the existing graphene quantum dots, the bactericidal effect is as follows: the antibacterial effect comparison of the nitrogen and silicon co-doped graphene quantum dots prepared in the application (taking example 17 as an example) with the antibacterial effect of bacillus subtilis performed by the graphene quantum dots synthesized by a one-step hydrothermal method with citric acid as a precursor in a reference (d.qu, m.zheng, l.zhang, h.zhao, z.xie, x.king, r.e.haddad, h.fan, z.sun, Formation mechanism and optimization of high yield luminescence N-doped graphene quantum dots, scientific reports,4(2014) 5294) is as follows: 100. mu.L of the above bacterial mother solution was transferred to 2 sterile test tubes, and 900. mu.L of physiological saline, 70. mu.L of the graphene quantum dots synthesized in example 17 (N, Si-GQDs) or the graphene quantum dots synthesized by the literature method were added, respectively, wherein the concentrations of the graphene quantum dots synthesized in example 17 (N, Si-GQDs) and the graphene quantum dots synthesized by the literature method were 2.16X 10^-4g/mL, after incubation for 24h at 37 ℃, the bactericidal effect is compared, and the result is shown in FIG. 13, wherein (a) is clear and transparent, and (b) is turbid, which indicates that the nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs) synthesized by the method have obvious antibacterial effect on Bacillus subtilis and have larger biomedical application prospect compared with the literature, and have better antibacterial advantage than the graphene quantum dots synthesized by the reference (D.Qu, M.Zheng, L.Zhang, H.ZHao, Z.Xie, X.Jing, R.E.Haddad, H.Fan, Z.Sun, Formation mechanisms and timing of high yield N-doped graphene dots, Scientific Reports,4(2014) 5294.).

And (3) economic evaluation:

in the actual process of producing nitrogen and silicon co-doped graphene quantum dots (N, Si-GQDs), compared with the economic method for synthesizing graphene quantum dots (small molecule citric acid "bottom-up" method), the method produces 1 ton (1000L) of graphene quantum dots, and the cost and the defect are shown in table 3 below:

table 4 cost comparison for preparing 1 ton graphene quantum dots

The graphene quantum dot concentration calculation method comprises the following steps: reference (d.qu, m.zheng, l.zhang, h.zhao, z.xie, x.king, r.e.haddd, h.fan, z.sun, Formation mechanism and optimization of high yield graphene quantites, Scientific Reports,4(2014)5294.) calculated as carbon source-concentration of 5mL graphene quantum dots per 1mmol citric acid synthesized is 0.2 mol/L-42 mg/mL-42 g/L, the amount of the substance of the desired ethylenediamine is 3 times that of citric acid.

The inventor finds out through a great deal of research that: when the mass ratio of the carbon powder to the ethylenediamine is controlled to be 5 (9-45), the reaction temperature is 160-200 ℃, and the reaction time is 2-16 h, the prepared silicon-nitrogen co-doped graphene quantum dots (N, Si-GQDs) all accord with the characterization results of the UV-vis absorption spectrum, the fluorescence spectrum, the FTIR spectrum, the Transmission Electron Microscope (TEM), the zeta potential, the X-ray electron energy spectrum (XPS), the X-ray diffraction (XRD), the synchronous thermal analysis and the like;

when the mass ratio of the G carbon powder to the ethylenediamine is further controlled to be 5 (18-36), the fluorescence intensity of the prepared silicon nitrogen co-doped graphene quantum dots (N, Si-GQDs) can reach over 1041, and when the mass ratio of the G carbon powder to the ethylenediamine is controlled to be 5:27, the fluorescence intensity of the prepared silicon nitrogen co-doped graphene quantum dots (N, Si-GQDs) can reach 1850.

When the reaction temperature is controlled to be 160 ℃ or 180 ℃ and the reaction time is 4-16 h, the quantum yield of the prepared silicon nitrogen co-doped graphene quantum dots (N, Si-GQDs) can reach more than 10%, and further when the reaction temperature is controlled to be 160 ℃ and the reaction time is 8-16 h, the quantum yield can reach more than 15%; when the reaction temperature is controlled to be 180 ℃ and the reaction time is 4-16 h, the quantum yield of the prepared nitrogen-codoped graphene quantum dots (N, Si-GQDs) can reach more than 15%;

when the reaction temperature is controlled to be 200 ℃ and the reaction time is 2-16 h, the quantum yield of the prepared silicon-nitrogen co-doped graphene quantum dots (N, Si-GQDs) can reach more than 15%, and when the reaction time is controlled to be 4h, the quantum yield of the prepared silicon-nitrogen co-doped graphene quantum dots (N, Si-GQDs) can reach more than 19%.

It should be noted that the above examples are only for further illustration and description of the technical solution of the present invention, and are not intended to further limit the technical solution of the present invention, and the method of the present invention is only a preferred embodiment, and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The silicon-nitrogen co-doped graphene quantum dot is characterized by being prepared from carbon powder and ethylenediamine, wherein the carbon powder contains silicon dioxide.

2. The preparation method of the silicon-nitrogen co-doped graphene quantum dot is characterized by comprising the following steps of:

dissolving carbon powder and ethylenediamine in water according to the mass ratio of 5 (9-45), reacting at 160-200 ℃ for 2-16 h, and filtering to obtain the catalyst.

3. The preparation method of the silicon nitrogen co-doped graphene quantum dot according to claim 2, wherein the mass ratio of the carbon powder to the ethylenediamine is 5 (18-36);

preferably, the mass ratio of carbon powder to ethylenediamine is 5: 27.

4. The preparation method of the silicon nitrogen co-doped graphene quantum dot according to claim 2, wherein the mass percentage of the carbon powder in the total reaction system is 1.5-2%.

5. The preparation method of the silicon nitrogen co-doped graphene quantum dot according to any one of claims 2 to 5, wherein the carbon powder is waste printer carbon powder.

6. The preparation method of the silicon nitrogen co-doped graphene quantum dot according to any one of claims 2 to 5, wherein the reaction temperature is 160 ℃, and the reaction time is 4-16 h;

preferably, the reaction temperature is 160 ℃, and the reaction time is 8-16 h.

7. The preparation method of the silicon nitrogen co-doped graphene quantum dot according to any one of claims 2 to 5, wherein the reaction temperature is 180 ℃ and the reaction time is 4-16 h;

preferably, the reaction temperature is 180 ℃ and the reaction time is 6-12 h.

8. The preparation method of the silicon nitrogen co-doped graphene quantum dot according to any one of claims 2 to 5, wherein the reaction temperature is 200 ℃ and the reaction time is 4-16 h;

preferably, the reaction temperature is 200 ℃, and the reaction time is 4-8 h;

preferably, the reaction temperature is 200 ℃ and the reaction time is 4 h.

9. The application of the silicon nitrogen co-doped graphene quantum dot as defined in any one of claims 1 to 8 in the aspect of antibiosis;

preferably, the bacteria are Escherichia coli and Bacillus subtilis.

10. The application of the silicon nitrogen co-doped graphene quantum dot in the antibacterial aspect of any one of claims 1 to 8, wherein the minimum bactericidal concentration in the application of resisting escherichia coli is 2.16 x 10^-4g/mL。