CN111635144A

CN111635144A - Preparation method of reduced graphene oxide film capable of enhancing carbon dot fluorescence

Info

Publication number: CN111635144A
Application number: CN202010623215.4A
Authority: CN
Inventors: 孙向英; 翁文婷; 何维; 刘斌
Original assignee: Huaqiao University
Current assignee: Huaqiao University
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2020-09-08

Abstract

The invention discloses a reduced graphene oxide film capable of enhancing carbon dot fluorescence, a preparation method and application thereof, and the reduced graphene oxide film ErGO is rapidly prepared by adopting a cyclic voltammetry method and a constant-potential method. According to the invention, the polyelectrolyte molecular layer is assembled on the surface of the basement membrane, the spacing distance between ErGO and the carbon point is accurately regulated and controlled, and the fluorescence signal of the carbon point on the outer layer of the self-assembled membrane can be enhanced. The graphene substrate prepared by the invention has the advantages of low price and environmental protection which cannot be compared with a noble metal nano enhanced substrate, and can solve the problems of weak fluorescence signal and low detection sensitivity of a fluorescence sensing film.

Description

Preparation method of reduced graphene oxide film capable of enhancing carbon dot fluorescence

Technical Field

The invention relates to a reduced graphene oxide film capable of enhancing carbon dot fluorescence, a preparation method and application.

Background

The Surface Enhanced Fluorescence (SEF) effect refers to a technique for enhancing the fluorescence emission of a fluorescent substance by using the Surface plasma oscillation and electromagnetic field cutting effect of a special substance Surface or a nanostructure. The problem of low sensitivity of fluorescence analysis can be solved essentially.

Many of the studies on the fluorescence enhancement of metal nanoparticles have been verified to be based on the Surface Plasmon Resonance (SPR) effect. Research has shown that the formation of MEF on the surface of metal nanomaterials is influenced by three main factors: (1) the degree of spectral overlap of the two; (2) the distance between the fluorophore and the metal; (3) nanoparticles that enhance the structure and properties of the substrate (with tips, edges and corners) can enhance fluorescence more efficiently. In addition, the fluorescence intensity depends on the degree of polarization of the fluorescence molecules and the number and density of the fluorophores deposited on the surface of the metal particles. Studies on the enhanced fluorescence of metal surfaces of various types of metal nanometers have been reported successively. However, the fluorescence enhancement systems established based on the metal nano-substrate have the defects of easy oxidation and instability of substrate raw materials, relatively high cost, environmental pollution and the like. In addition, when the metal nano is used as a SPR research material, the optical loss ratio of the metal nano is large, the electromagnetic property of the metal nano is difficult to change, and the regulation of SP propagation and resonance is not facilitated.

It is reported that graphene has a characteristic that plasmon polariton enhances a near-field fluorescence signal, and SPs is mostly generated in a graphene lattice structure within 5 layers formed on the SiC surface by a solid-phase growth method. The graphene sheets mechanically exfoliated from the highly oriented pyrolytic graphite can induce a resonant plasma to enhance the fluorescence signal of the adjacent zinc oxide nanolayers. However, physically exfoliated graphene is stable in properties and poor in solubility, and a suspended aqueous solution thereof is easily agglomerated and precipitated, which is not favorable for forming a uniform film formation process on a solid substrate. The graphene has to be coated by chitosan and then deposited on a glass substrate, and the fluorescence enhancement effect on carbon dots is researched, so that the structure of few-layer graphene is difficult to keep in the preparation process of the film substrate. The Graphene Oxide (GO) serving as a graphene oxidized derivative has good solubility, and the reduced graphene can be prepared by a polyelectrolyte PDDA (polymer dispersed data acquisition) coating synchronous chemical reduction method, so that the enhancement effect on a carbon dot fluorescence signal is realized. However, the whole process of preparing the thin film substrate involves a plurality of synthesis steps, is cumbersome, and introduces chemical substances into the graphene substrate. The most ideal method for reducing graphene oxide should be green, safe and simple, minimizing the introduction of impurities and defects.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides the reduced graphene oxide film capable of enhancing the carbon dot fluorescence, and the preparation method and the application thereof, and solves the problems in the background art.

One of the technical schemes adopted by the invention for solving the technical problems is as follows: the preparation method of the reduced graphene oxide film capable of enhancing carbon dot fluorescence is provided, and comprises the following steps:

1) depositing graphene oxide on the conductive FTO slide by adopting a cyclic voltammetry method to prepare an FTO/GO film;

2) reducing the graphene oxide by combining a constant potential method to prepare an FTO/ErGO film;

3) the FTO/ErGO membrane is sequentially put into a PDDA solution and a PSS solution, and is alternately and repeatedly carried out, and a self-assembly membrane FTO/ErGO/[ PDDA/PSS ] is prepared in a self-assembly mode]_nSAMs, wherein n is 1-5.

4) Soaking the self-assembled film in a fluorescent carbon dot solution to prepare the FTO/ErGO/[ PDDA/PSS ]]_nthe/CDs SAMs are shown in the specification, wherein n is 1-5;

in a preferred embodiment of the present invention, n is 3, and step 3) is performed to obtain a self-assembled film FTO/ErGO/[ PDDA/PSS ]]₃SAMs, step 4) preparation to FTO/ErGO/[ PDDA >PSS]₃/CDs SAMs。

In a preferred embodiment of the present invention, in step 1), the cyclic voltammetry includes the following steps:

a three-electrode system with a conductive FTO slide as a working electrode, an Ag-AgCl electrode as a reference electrode and a platinum wire electrode as a counter electrode is controlled at 0.02 g.L^-1And (3) in HAc-NaAc buffer solution with the pH value of GO being 5.0, carrying out cyclic voltammetry curve scanning at the scanning speed of 50mV/s and the voltage of-0.6-1.0V, wherein the number of scanning circles is 8, and preparing the FTO/GO film in one step.

In a preferred embodiment of the present invention, in the step 2), the potentiostatic method includes the following steps:

a three-electrode system with an FTO/GO film as a working electrode, an Ag-AgCl electrode as a reference electrode and a platinum wire electrode as a counter electrode is placed in a range of 0.1 mol.L^-1And (3) carrying out constant potential reduction in KCl electrolyte, wherein the potential is-1.4V, and the time is 1000s, so as to prepare the FTO/ErGO film.

In a preferred embodiment of the present invention, step 3) comprises the following steps:

putting the FTO/ErGO membrane into a PDDA solution with the volume fraction of 1% to assemble for 1h, taking out, cleaning with ultrapure water, and putting into a constant temperature and humidity box to dry; then placing at 1 g.L^-1The PSS solution is assembled for 1h, is taken out and then is cleaned by ultrapure water, and is placed in a constant temperature and humidity box for airing; the above process is alternately repeated for 3 times to prepare the self-assembled film FTO/ErGO/[ PDDA/PSS]₃SAMs；

Wherein the PDDA solution and the PSS solution contain NaCl with the volume fraction of 1 percent.

In a preferred embodiment of the present invention, step 4) includes the following steps:

soaking the self-assembled film in the fluorescent carbon dot solution for 3h, taking out the self-assembled film, and drying the self-assembled film by using nitrogen to obtain the enhanced carbon dot fluorescent self-assembled film FTO/ErGO/[ PDDA/PSS ]]_n/CDs SAMs。

In a preferred embodiment of the invention, the method further comprises 0) pretreatment, wherein the pretreatment comprises preparation of a graphene oxide mother solution and cleaning of the conductive FTO glass slide.

In a preferred embodiment of the present invention, the preparation of the graphene oxide mother liquor includes the following steps:

uniformly dispersing graphene oxide powder in ultrapure water, dissolving in ultrasonic wave at a temperature of not higher than 40 ℃ for 1h to prepare 0.2 g.L^-1The clarified graphene oxide solution is a mother liquor.

In a preferred embodiment of the present invention, the cleaning of the conductive FTO slide comprises the following steps:

and (3) enabling the conductive surface of the conductive FTO slide to face upwards, washing the conductive surface of the conductive FTO slide for 30min by using ultrapure water, then washing the conductive surface of the conductive FTO slide for 10min by using absolute ethyl alcohol under an ultrasonic condition, then ultrasonically washing the conductive surface of the conductive FTO slide for 30min in a Piranha solution which is prepared currently, finally ultrasonically cleaning the conductive surface of the conductive FTO slide for multiple times by using the ultrapure water, and drying the conductive surface of.

The second technical scheme adopted by the invention for solving the technical problems is as follows: the reduced graphene oxide film capable of enhancing carbon dot fluorescence prepared by the method is a carbon dot fluorescence enhancement self-assembled film FTO/ErGO/[ PDDA/PSS ]]₃/CDs SAMs。

The third technical scheme adopted by the invention for solving the technical problems is as follows: the application of the reduced graphene oxide film capable of enhancing carbon dot fluorescence in fluorescence analysis and detection is provided, and the reduced graphene oxide film can be used as a substrate film for enhancing a fluorescent probe signal.

Compared with the background technology, the technical scheme has the following advantages:

1. the graphene oxide which is cheap and easy to obtain is selected as the material. Compared with gold, silver nanometer, rare metal nanometer materials and other nanometer materials, the material has the advantages of stable chemical property, large specific surface area, excellent photoelectric performance and the like. The complex synthesis steps are avoided, so the preparation process is green and environment-friendly, secondary pollution is not generated, and the production cost is saved.

2. The invention adopts a green and safe process for reducing graphene oxide by an electrochemical method. The requirements of high-performance and high-cost equipment of traditional methods such as mechanical stripping, chemical vapor deposition, epitaxial growth and the like are not required. The simple method for electrochemically reducing the graphene overcomes the defect that the defects of graphene sheets are increased in the preparation process by a thermal reduction method. Avoiding the operation of introducing toxic chemical substances and impurity atoms in the chemical reduction process. Makes up the defects of long time consumption and large radiation of the photo-reduction method.

3. The invention adopts the layer-by-layer self-assembly technology to construct the film. The method has the advantages that the spacing distance between the film substrate and the probe can be accurately controlled, and the charge state of the surface of the assembled film can be freely designed.

Drawings

FIG. 1 is a graph of the trend of the corresponding values of (a) cyclic voltammetry curves and (b) AC impedance curves (Nyquist plot) and (c) for FTO/GO membranes formed under different cyclic voltammetry conditions.

FIG. 2 shows a plot of (a) cyclic voltammetry curves, (b) AC impedance curves, (c) corresponding trend of values, (d) Raman spectra, (e) surface enhanced fluorescence spectra, and (f) corresponding trend of values for FTO/ErGO membranes formed at different reduction potentials.

FIG. 3 shows the cyclic voltammograms (a) and the AC impedance curves (b) and the corresponding trend plots (c) for the values, (d) the Raman spectra and (e) the surface-enhanced fluorescence spectra and (f) the corresponding trend plots for the values of FTO/ErGO films formed at different reduction times.

Fig. 4 is a graph showing (a) cyclic voltammetry curves, (b) alternating current impedance curves, (c) corresponding numerical value change trends, (d) raman spectra, (e) surface enhanced fluorescence spectra, and (f) corresponding numerical value change trends of FTO/ErGO films formed under different graphene oxide concentrations.

FIG. 5 shows FTO/GO/[ PDDA/PSS]_nPerCDs and FTO/ErGO/[ PDDA/PSS]_n(a) fluorescence spectrum, (b) fluorescence decay curve, (c) FTO/GO/[ PDDA/PSS ] of/CDs]_nConfocal laser microscopy of/CDs and (d) FTO/ErGO/[ PDDA/PSS]_nConfocal laser microscopy of/CDs and (e) comparison of luminescence signals at different sites.

FIG. 6 shows (a) cyclic voltammetry curves, (b) AC impedance curves, (c) Raman spectra and (d) surface enhanced fluorescence spectra of different types of FTO/ErGO membranes prepared by graphene oxide reduction.

Detailed Description

Example 1

The preparation method of the reduced graphene oxide film capable of enhancing carbon dot fluorescence in the embodiment comprises the following steps:

0) pretreatment:

a. uniformly dispersing graphene oxide powder in ultrapure water, and dissolving in ultrasonic waves at a temperature of not higher than 40 ℃ for 1 h. The resulting mixture was mixed to give 0.2 g.L^-1The graphene oxide clarified solution is mother liquor, and is diluted to the required concentration by ultrapure water according to the later experimental requirements;

b. the conductive FTO glass slide with the conductivity of 1cm × 2cm was faced up, washed with ultrapure water for 30min, then with absolute ethanol under ultrasonic conditions for 10min, and then in Piranha solution (98% H)₂SO₄:30％H₂O₂7:3, V/V, just after preparation), ultrasonically washing for 30min, finally ultrasonically cleaning with ultrapure water for multiple times, and drying in a constant temperature and humidity cabinet after cleaning;

1) preparation of FTO/GO film:

the three-electrode system with FTO conductive glass as a working electrode, an Ag-AgCl electrode as a reference electrode and a platinum wire electrode as a counter electrode is controlled at 0.02 g.L^-1And (3) in HAc-NaAc buffer solution with the pH value of GO being 5.0, carrying out cyclic voltammetry curve scanning at the scanning speed of 50mV/s and the voltage of-0.6-1.0V, wherein the number of scanning circles is 8, and preparing the FTO/GO film in one step. Taking out and flushing, and drying by nitrogen.

2) Preparation of FTO/ErGO film:

3) Preparation of self-assembled films:

putting the FTO/ErGO membrane into a 1% (V/V) PDDA solution (containing 1% NaCl) for assembly for 1h, taking out, cleaning with ultrapure water, and placing in a constant temperature and humidity box for drying. Then placing at 1 g.L^-1The PSS solution (containing 1% NaCl) is assembled for 1h, taken out and then cleaned by ultrapure water, and then placed in a constant temperature and humidity box for drying. This process was repeated 3 times alternately to form FTO/ErGO/[ PDDA/PSS ]]₃SAMs。

4) Preparing a fluorescent carbon dot sensing film:

soaking the self-assembled film in a fluorescent carbon dot solution for 3h, taking out, and drying by using nitrogen to obtain FTO/ErGO/[ PDDA/PSS ]]₃/CDs SAMs。

The repeated oxidation-reduction process by using the cyclic voltammetry results in the formation of multi-layer graphene at the folded edge, which is favorable for the uniform deposition of graphene oxide on the electrode, but the reduction is not thorough, and the potentiostatic method is more favorable for the reduction of the graphene oxide layer, so that the preparation of the graphene oxide substrate is performed by combining the cyclic voltammetry with the potentiostatic method. Prepared FTO/ErGO/[ PDDA/PSS]₃the/CDs SAMs can be used as a graphene substrate to be applied to enhancing fluorescent probe signals, has the advantages of stable chemical performance, low price and environmental protection which cannot be achieved by a noble metal nano enhanced substrate, and can solve the problems of weak fluorescent signals and low detection sensitivity of a fluorescent film sensing film.

Comparative experiment of cyclic voltammetry deposition conditions

1. And selecting the scanning speed and time of the CV as variables to detect the electrochemical performance of the prepared FTO/GO under various conditions. Selecting a CV sweep rate variable of 10mV s^-1、30mV·s^-1、50mV·s^-1、60mV·s^-1. When the scanning speed is too slow, the phenomenon that the graphene layer at the folding edge adsorbs appears in FTO (very fast optical transmission) indication easily, when the scanning speed is too fast, GO is difficult to attach to FTO glass sheets through an electrochemical method, and a uniform graphene layer is difficult to form. As can be seen, the sweep rate of cyclic voltammetry was 50 mV. multidot.s^-1Is the best condition.

2. Keeping 50 mV.s^-1Selecting different time as variables, and investigating the influence of different scanning turns (segments) of 4, 6, 8, 10 and 12 on the electrochemical performance of the prepared graphene film. The results are shown in figure 1, with an increase in the number of stages implying an increase in reduction time, with a corresponding increase in Δ Ε of the produced GO film followed by a decrease, reaching a minimum at segment 8. The high-frequency zone half-circles on the corresponding Nyquist plots increase with increasing reduction time. This is because when the number of scanning turns is too small, GO is difficult to attach to the FTO slide, and even the FTO part surface is not covered with GO. However, as the number of scanning turns increasesAnd the GO layer gradually becomes thicker, the conductivity gradually weakens, and if the edge folding graphene layer is formed, the completeness and the uniformity of the graphene reduction by the later-stage potentiostatic method are not facilitated.

Comparative experiment of reduction potential by potentiostatic method

The FTO/ErGO prepared under different reduction potentials is used as a working electrode to draw a cyclic voltammetry and alternating current impedance curve, and the result shows that as shown in figure 2, when the deposition potential is-1.4V, the redox potential difference delta E formed on the graphene film by the redox couple is minimum, and the electron transfer resistance R on the corresponding Nyquist diagram_etIs smaller. The reason for this analysis may be that the GO surface is reduced to a relatively greater extent in the same time as the reduction potential is smaller, but when the reduction potential is too negative, it results in too many crystal defects being formed on the formed ErGO surface, see fig. 2 (c). When the sensing film of the enhanced fluorescent carbon dots is prepared corresponding to the graphene substrate, the enhancement capability is reduced. In combination with the above analysis, the method selects-1.4V as the optimal reduction potential.

Comparison experiment of reduction time by potentiostatic method

The effect of different reduction times on the formation of ErGO films was examined under the conditions of a-1.4V reduction potential. The results are shown in FIG. 3, where the delta E of the cyclic voltammogram of the FTO/ErGO membranes made decreased first and then increased with time as the reduction time was varied from small to large. The electron transport properties of the corresponding FTO/ErGO membrane decrease and then increase over time. The experimental result of the Raman spectrum combined with the ErGO membrane shows that when the reduction time is too short, GO on the surface of the FTO slide is not completely reduced, most of the surface of the FTO slide still has residual insulation GO, and the conductivity is poor. With the increase of the reduction time, the degree of reduced GO gradually increases, and the conductivity of the ErGO film gradually improves. When the reduction time exceeds 1000s, the crystal defects on the graphene surface are too much due to excessive reduction of the ErGO on the surface of the FTO glass slide, and the conductivity of the ErGO film is reduced. In the Raman spectrum of ErGO film prepared under the condition of 1200s reduction time, the D peak is far higher than the G peak, and is sp²The increase of hybrid clusters results in larger crystal defects. Constructing fluorescence enhancement on the prepared reduced graphene oxide substrate according to an experimental methodA film. The corresponding fluorescence spectra are shown in fig. 3(d), and the best fluorescence enhancement occurs for the ErGO films prepared at 700s and 1000s reduction times. It can be seen that the enhancement effect of the graphene substrate on the fluorescent probe is related to the integrity of the lattice structure obtained by reducing the graphene to a certain degree.

Comparative experiment of graphene oxide concentration

The experimental results are shown in fig. 4, along with the increase of the concentration of the GO solution, the formed FTO/ErGO has the enhancement of the electron transfer capability, the potential difference △ Ep of the oxidation reduction peak of the cyclic voltammetry curve is reduced, and the electron transfer R corresponding to the alternating current impedance spectrogram_etAnd also becomes smaller. The corresponding Raman spectrum showed an increasing degree of reduction, when 0.020 g.L was used, as shown in FIG. 4(c)^-1The fluorescence enhancement effect of the FTO/ErGO prepared by the GO solution on carbon dots is best, and the fluorescence enhancement effect is shown in figure 4(d), so that the concentration of 0.020 g.L^-1Is the optimum concentration.

Fifth, self-assembled film performance verification experiment

Assembling the FTO/ErGO substrate with the spacing layer through the electrostatic adsorption effect of polyelectrolyte, finally assembling positive charge fluorescent carbon dots WCDs @ PDDA at the tail end, and constructing a sensing film FTO/ErGO/[ PDDA/PSS ] of the graphene enhanced fluorescent carbon dots]₃(iii)/CDs. The graphene films before and after reduction are used as substrates to construct a fluorescent carbon dot self-assembled film, and the comparative fluorescence spectrum is shown in fig. 5 (a). FTO/ErGO/[ PDDA/PSS]₃/CDs compared to FTO/GO/[ PDDA/PSS]₃The relative fluorescence intensity of the/CDs self-assembled films was enhanced by nearly 3-fold. The fluorescence lifetime data of the corresponding fluorescent self-assembled film is shown in FIG. 5(b), FTO/GO/[ PDDA/PSS]₃The average fluorescence lifetime of the fitted/CDs fluorescence decay curve is 2.636ns, while FTO/ErGO/[ PDDA/PSS ]]₃The fluorescence lifetime of/CDsSAMs was shortened to 1.887 ns. The results are consistent with the conclusion that the metal nanoparticles increase the fluorescence intensity and the radiation decay rate of CDs based on the surface plasmon effect.

And (3) verifying the self-assembled film before and after enhancement by adopting a laser confocal fluorescence microscopy technology under the same condition. The results are shown in FIG. 5(c), FTO/ErGO/[ PDDA/PSS]_nThe luminescence property of/CDs is obviously stronger than FTO/GO/[ PDDA/PSS]_nand/CDs, comparing optical signals generated on nine uniformly distributed sites in the interface, and further illustrating the characteristics of the graphene enhanced carbon quantum dots.

Sixthly, comparing the influence of the type of the graphene oxide on the enhancement of the fluorescence effect

Four types of electrolytes, namely single-layer Graphene Oxide (GO), aminated graphene oxide (NGO), Carboxylated Graphene Oxide (CGO) and thiolated graphene oxide (SGO), are respectively selected and prepared into corresponding FTO/ErGO membranes according to the method in the embodiment 1, and the electrochemical curves of the FTO/ErGO membranes are mapped and subjected to spectral characterization.

Experimental results as shown in fig. 6, various types of reduced graphene membranes all exhibited a decrease in conductivity performance compared to FTO electrodes. Among them, only the ErGO and ErCGO films with different oxygen contents have better reversibility, while the ErNGO and ErSGO films with heteroatom introduced have reduced electrochemical reversibility and show poorer conductive capability. And heteroatom is introduced into the structures of NGO and SGO films, so that too many crystal defects are easily formed after reduction, and the electron transfer is not facilitated. The ErGO and ErCGO films in the corresponding Raman spectrogram show obvious reduction phenomenon and have a large amount of sp²A hybrid cluster. Under the same reduction condition, the ErNGO and ErSGO films are difficult to form graphene lattice structures, so that obvious characteristic peaks of D and G do not appear. The enhancement effect on carbon spots was also correspondingly best seen with the ErGO and ErCGO films as substrates, while the ErNGO and ErSGO films did not have significant enhancement effects. Further verifying that the fluorescence enhancement effect is related to the complete lattice structure of graphene.

The above description is only a preferred embodiment of the present invention, and therefore should not be taken as limiting the scope of the invention, which is defined by the appended claims and their equivalents.

Claims

1. The preparation method of the reduced graphene oxide film capable of enhancing carbon dot fluorescence is characterized by comprising the following steps of: the method comprises the following steps:

3) the FTO/ErGO membrane is sequentially put into a PDDA solution and a PSS solution, and is alternately and repeatedly carried out, and a self-assembly membrane FTO/ErGO/[ PDDA/PSS ] is prepared in a self-assembly mode]_nSAMs, wherein n is 1-5;

4) soaking the self-assembled film in a fluorescent carbon dot solution to prepare the FTO/ErGO/[ PDDA/PSS ]]_n/CDs SAMs。

2. The method for preparing a reduced graphene oxide film capable of enhancing fluorescence of carbon dots according to claim 1, wherein the method comprises the following steps: in step 1), the cyclic voltammetry comprises the following steps:

3. The method for preparing a reduced graphene oxide film capable of enhancing fluorescence of carbon dots according to claim 1, wherein the method comprises the following steps: in the step 2), the constant potential method comprises the following steps:

4. The method for preparing a reduced graphene oxide film capable of enhancing fluorescence of carbon dots according to claim 1, wherein the method comprises the following steps: the step 3) comprises the following steps:

putting the FTO/ErGO membrane into a PDDA solution with the volume fraction of 1% to assemble for 1h, taking out, cleaning with ultrapure water, and putting into a constant temperature and humidity box to dry; then placing at 1 g.L^-1In the PSS solution of (1)Assembling for 1h, taking out, cleaning with ultrapure water, and air drying in a constant temperature and humidity box; the above processes are alternately repeated to prepare the self-assembled film FTO/ErGO/[ PDDA/PSS ]]₃SAMs；

5. The method for preparing a reduced graphene oxide film capable of enhancing fluorescence of carbon dots according to claim 1, wherein the method comprises the following steps: the step 4) comprises the following steps:

6. The method for preparing a reduced graphene oxide film capable of enhancing fluorescence of carbon dots according to claim 1, wherein the method comprises the following steps: and also comprising 0) pretreatment, wherein the pretreatment comprises preparation of a graphene oxide mother solution and cleaning of the conductive FTO glass slide.

7. The method for preparing a reduced graphene oxide film capable of enhancing fluorescence of carbon dots according to claim 6, wherein the method comprises the following steps: the preparation method of the graphene oxide mother liquor comprises the following steps:

8. The method for preparing a reduced graphene oxide film capable of enhancing fluorescence of carbon dots according to claim 6, wherein the method comprises the following steps: the cleaning of the conductive FTO glass slide comprises the following steps:

9. The reduced graphene oxide film capable of enhancing fluorescence of carbon dots prepared by the method according to any one of claims 1 to 8, wherein: the reduced graphene oxide film is an enhanced carbon point fluorescence self-assembled film FTO/ErGO/[ PDDA/PSS ]]_nthe/CDsSAMs are shown in the specification, wherein n is 1-5.

10. The use of the reduced graphene oxide film capable of enhancing fluorescence of carbon dots according to claim 9 in fluorescence analysis and detection, wherein: used as a substrate film for enhancing the signal of the fluorescent probe.