Graphene morphology control method, sers film and detection application

Abstract

The application provides a graphene morphology control method, a SERS film and a detection application, and comprises the following steps: placing a substrate in a quartz tube and vacuumizing; introducing hydrogen and argon into the quartz tube, and then heating to T1, wherein 600 DEG C >= T1 >= 500 DEG C; stopping the introduction of hydrogen and argon into the quartz tube, starting a plasma source, and starting to introduce methane to grow graphene matrix on the substrate; closing the plasma source and stopping the introduction of methane; heating the quartz tube to T2, wherein 800 DEG C >= T2 >= 700 DEG C, and then starting to simultaneously introduce methane and ammonia, starting the plasma source and increasing the power to P, wherein P >= 200 W, so that the graphene matrix is converted into flower cluster graphene.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of graphene, in particular to a graphene morphology control method, a SERS film and a detection application. BACKGROUND

[0002] The preparation process of graphene is simple, low in cost and has good chemical activity, and is a potential SERS film material. However, the Raman intensity of the SERS film composed of intrinsic graphene is low, which is difficult to meet the actual detection needs. Therefore, some existing technologies attempt to dope single element in graphene in order to improve its detection ability, but the improvement effect is often limited.

[0003] Based on the above problems, some existing technologies attempt to jointly dope graphene with multiple elements in order to further improve the detection performance of the SERS film, but in fact, in most cases, the roles of different elements in the SERS film conflict with each other, the detection ability of the SERS film is limited, and even it is difficult to ensure the improvement of the detection effect relative to the intrinsic graphene. SUMMARY

[0004] Therefore, it is necessary to provide a graphene morphology control method, a SERS film and a detection application in order to solve the problem of insufficient detection ability of the SERS film composed of graphene.

[0005] The technical scheme provided by the present application is as follows:

[0006] A graphene morphology control method comprises the following steps:

[0007] Place the substrate in the quartz tube and vacuumize it;

[0008] Introduce hydrogen and argon into the quartz tube, and then heat it to T1, wherein 600℃≥T1≥500℃;

[0009] Stop introducing hydrogen and argon into the quartz tube, start the plasma source, and start introducing methane to grow graphene matrix on the substrate;

[0010] Turn off the plasma source and stop introducing methane;

[0011] Heat the quartz tube to T2, wherein 800℃≥T2≥700℃, and then start introducing methane and ammonia simultaneously, start the plasma source and increase the power to P, P≥200W, so as to convert the graphene matrix into flower cluster graphene.

[0012] During the process of converting the graphene matrix into flower cluster graphene, the volume flow ratio of methane to ammonia is 15:1.

[0013] The T2 of the application is 750 DEG C, and the P is 250 W.

[0014] The growth time of the graphene substrate is 60 minutes, the power of the plasma source during the growth process is 200 W, and the volume flow rate of the methane is 15 sccm.

[0015] The SRRS film comprises the flower cluster-shaped graphene prepared by the graphene morphology control method.

[0016] The SRRS film is used for detecting one or more of DBP, DEHP (di(2-ethylhexyl) phthalate), DNDP, EB (erythrosin B), R6G (rhodamine 6G) and CRV (crystal violet).

[0017] The application has the following beneficial effects:

[0018] The application first only introduces methane to prepare the graphene substrate, and then introduces methane and ammonia at the same time, so that the graphene substrate gradually changes into nitrogen-doped flower cluster-shaped graphene. In the above process, the ammonia not only enables the nitrogen to be doped in the graphene, so as to realize the adjustment of the Fermi level, but also controls the morphology of the graphene.

[0019] The flower cluster-shaped graphene is a three-dimensional nanocage-shaped morphology, which is manifested as a spherical particle on one hand and a flower cluster-shaped morphology on the surface of the spherical particle on the other hand. Therefore, the specific surface area of the graphene is greatly improved, so that the graphene has a very strong adsorption capacity. In addition, the unique nanocavity and cavity resonance effect of the flower cluster-shaped graphene improve the absorption effect of the flower cluster-shaped graphene on photons, so that the flower cluster-shaped graphene exhibits significant optical properties. At the same time, the three-dimensional nanocage-shaped morphology of the flower cluster-shaped graphene enables the local electromagnetic field strength of the surface of the flower cluster-shaped graphene to be improved, so that the interaction between the flower cluster-shaped graphene and photons is further enhanced.

[0020] The Fermi level adjustment effect of the nitrogen-doped flower cluster-shaped graphene further improves the conductive performance of the flower cluster-shaped graphene, which is helpful to the transfer of the carriers. The electrophilicity and electron-donating property of the nitrogen atom enable the nitrogen atom to act as the center of the adsorbed molecules or ions, so that the nitrogen atom has good effects on the electron transfer, catalytic reaction and substance adsorption.

[0021] In combination with the morphology characteristics of the flower cluster-shaped graphene and the dual characteristics of the nitrogen doping, the SRRS film can detect more substances, and the lower limit of the detection concentration, the detection accuracy and the types of the detected substances can be increased. In addition, the SRRS film has the characteristics of being reusable, stable in results and the like. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The figure is the morphology of sample one in the embodiment 1 of the application;

[0023] Figure 2SEM image of sample two in comparative example 1 of the present application;

[0024] Figure 3 SEM image of sample three in comparative example 2 of the present application;

[0025] Figure 4 Three-dimensional model image, normalized electric field distribution image, and spatial distribution image of normalized power loss density of sample one in example 1 of the present application;

[0026] Figure 5 XPS image of sample N-1s of sample one in example 1 of the present application;

[0027] Figure 6 Water contact angle of sample one in example 1 of the present application;

[0028] Figure 7 Raman spectrum of sample one, sample two and sample three for detecting EB, R6G and CRV respectively (concentration is 10 -4 M);

[0029] Figure 8 Raman spectrum of sample one, sample two and sample three for detecting DBP, DEHP and DNDP respectively (concentration is 10 -2 M);

[0030] Figure 9 Raman spectrum of sample one for detecting EB, R6G and CRV with different concentrations;

[0031] Figure 10 Raman intensity distribution of D peak and G peak at different positions of sample one in the present application;

[0032] Figure 11 Raman intensity distribution of 2D peak at different positions of sample one in the present application;

[0033] Figure 12 Raman intensity distribution of D peak and G peak at different positions of sample one in the present application after adding DEHP dropwise;

[0034] Figure 13 Raman intensity distribution of 2D peak at different positions of sample one in the present application after adding DEHP dropwise;

[0035] Figure 14 Raman intensity distribution at different positions of sample one in the present application after adding EB, CRV and R6G respectively;

[0036] Figure 15 Raman intensity distribution of sample one in the present application after repeated washing and repeated addition of EB, CRV and R6G;

[0037] Figure 16 The Raman spectra of a sample of the present invention after adding different concentrations of DEHP (solvent is methanol) are shown.

[0038] Figure 17 The Raman spectral stability test results are shown for a sample of this invention after adding different concentrations of DEHP (methanol as solvent).

[0039] Figure 18 The Raman spectrum of a drop of perfume (diluted with ethanol) added to the sample of this invention is shown.

[0040] Figure 19 Raman spectral stability test of a drop of diluted perfume (ethanol diluted) for this invention. Figure 1 ;

[0041] Figure 20 Raman spectral stability test of a drop of diluted perfume (ethanol diluted) for this invention. Figure 2 ;

[0042] Figure 21 This is a SEM image of sample four in Comparative Example 3 of the present invention;

[0043] Figure 22 This is a SEM image of sample five in Comparative Example 4 of the present invention. Detailed Implementation

[0044] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0045] Example 1:

[0046] This embodiment provides an SRRS thin film, including a substrate and flower-like graphene located on the surface of the substrate.

[0047] The method for preparing flower-like graphene, namely the graphene morphology control method provided in this embodiment, includes the following steps:

[0048] Step 101: Place the substrate (in this embodiment, a 1cm×1cm Si substrate) in the quartz tube of the PECVD equipment (model BTF-1200C-II-AS-PECVD, purchased from Anhui Beyike Equipment Technology Co., Ltd.) and evacuate to 5Pa;

[0049] Step 102: a mixture of hydrogen and argon is introduced into the quartz tube, wherein the volume flow rate of hydrogen is 1sccm and the volume flow rate of argon is 10sccm, and then the interior of the quartz tube is heated to 550℃;

[0050] Step 103: when the temperature of the interior of the quartz tube reaches 550℃, the introduction of hydrogen and argon is stopped, and methane is introduced at a volume flow rate of 15sccm, the plasma source is started and the power is set to 200W, so as to grow a graphene base on the substrate, and the growth time in this embodiment is 60min;

[0051] Step 104: the plasma source is turned off, the introduction of methane is stopped, and then the interior of the quartz tube is heated to T2, and in this embodiment T2=750℃;

[0052] Step 105: a mixture of methane and ammonia is introduced into the quartz tube, wherein the volume flow rate of methane is 15sccm and the volume flow rate of ammonia is 1sccm, the plasma source is started and the power is set to 250W, so as to convert the graphene base into a flower-like graphene, and the duration of this step is 30min;

[0053] Step 106: the introduction of methane and ammonia is stopped, argon is introduced at a volume flow rate of 10sccm, so as to restore the interior of the quartz tube to atmospheric pressure, and then the flower-like graphene is cooled to room temperature.

[0054] Thus, a SRRS film (sample one) is obtained.

[0055] Comparative Example 1:

[0056] This comparative example also provides a SRRS film, and the preparation process thereof comprises the following steps:

[0057] Step 201: a substrate (1cm×1cm Si substrate is selected in this embodiment) is placed in a quartz tube of a PECVD device (model BTF-1200C-II-AS-PECVD, purchased from Anhui Beyike Equipment Technology Co., Ltd.), and vacuumized to 5Pa;

[0058] Step 202: a mixture of hydrogen and argon is introduced into the quartz tube, wherein the volume flow rate of hydrogen is 1sccm and the volume flow rate of argon is 10sccm, and then the interior of the quartz tube is heated to 550℃;

[0059] Step 203: When the temperature inside the quartz tube reaches 550℃, stop the hydrogen and argon gas, and introduce methane at a volume flow rate of 15sccm, start the plasma source and set its power to 200W, so as to grow graphene matrix on the substrate, and the growth time in this comparative example is 60min;

[0060] Step 204: Stop the methane and turn off the plasma source, and introduce argon at a volume flow rate of 10sccm, so that the inside of the quartz tube returns to atmospheric pressure, and then cool the graphene matrix to room temperature.

[0061] Thus, the SRRS film (sample two) is obtained.

[0062] Comparative Example 2:

[0063] Step 301: Place the substrate (1cm x 1cm Si substrate is selected in this example) in the quartz tube of the PECVD device (model BTF-1200C-II-AS-PECVD, purchased from Anhui Beyike Equipment Technology Co., Ltd.), and vacuumize to 5Pa;

[0064] Step 302: Introduce a mixed gas of hydrogen and argon into the inside of the quartz tube, wherein the volume flow rate of hydrogen is 1sccm, and the volume flow rate of argon is 10sccm, and then heat the inside of the quartz tube to 750℃;

[0065] Step 303: When the temperature inside the quartz tube reaches 750℃, stop the hydrogen and argon gas, and introduce a mixed gas of methane and ammonia, wherein the volume flow rate of methane is 15sccm, and the volume flow rate of ammonia is 1sccm, start the plasma source and set its power to 250W, and the growth time in this comparative example is 60min, thus obtaining nitrogen-doped graphene;

[0066] Step 304: Stop the methane and ammonia, and introduce argon at a volume flow rate of 10sccm, so that the inside of the quartz tube returns to atmospheric pressure, and then cool the nitrogen-doped graphene to room temperature.

[0067] Thus, the SRRS film (sample three) is obtained.

[0068] Referring to Figure 1 , which are the SEM, void degree and AFM images of sample one from left to right, it can be seen from the SEM image that sample one exhibits independent spherical cluster structures with a diameter of about 1μm, and from the void degree image, it can be seen that the porosity reaches 90%, thus indicating that sample one has a large specific surface area and more absorption sites. From the AFM image, it can be known that the average height is 800-1000nm.

[0069] On the contrary Figure 2 And Figure 3 In the absence of either step 103 or step 105, the morphology of sample one cannot be obtained, and the specific surface area and adsorption sites of sample two and sample three are significantly less than that of sample one.

[0070] See Figure 4 , from left to right are the three-dimensional model of a single spherical cluster structure in sample one, the normalized electric field distribution, and the spatial distribution of the normalized power loss density. This shows that sample one has a good absorption effect on light.

[0071] See Figure 5 , ~ 398.4, ~ 401.3, ~ 403.2 eV three peak position represents the existence of pyridine nitrogen, pyrrole nitrogen, graphite nitrogen, fully illustrates that the nitrogen atom of sample one has successfully entered the crystal lattice of graphene.

[0072] See Figure 6 , compared with the pure substrate, the water contact angle of sample one is larger, showing a strong hydrophobicity. This also shows that sample one has the potential characteristics of reusability.

[0073] See Figure 7 and Figure 8 , sample one, sample two and sample three are used to detect DBP (butyl phthalate), DEHP (di(2-ethylhexyl) phthalate), DNDP (didecyl phthalate), EB (erythrosine B), R6G (rhodamine 6G), CRV (crystal violet).

[0074] Among them, N-Graphene hydrangea / Si represents sample one, N-Graphene / Si represents sample three, and 3D-Graphene / Si represents sample two. It can be seen that for common pigments (EB, R6G and CRV), the Raman intensity of sample one is significantly higher than that of sample three and sample two. For common plasticizers (DBP, DEHP and DNDP), the Raman intensity of sample one is also significantly higher than that of sample three and sample two. The Raman intensity of sample one is greatly improved. It can be seen that step 103 and step 105 show a strong synergistic effect in the final sample one. That is, the doping of nitrogen and the modification of graphene morphology have a strong promotion effect on the SERS detection performance. The specific performance of the above two effects is to improve the specific surface area of sample one, and to improve the Fermi level and charge transport performance, thereby improving its ability to capture photons.

[0075] See Figure 9 , the detection limit of sample one for EB, CRV and R6G is 10 -11 M, 10-8 M, 10 -11 M. For EB, at 1344cm -1 The linear correlation coefficient R between its concentration and Raman intensity 2 It is 0.99351, at 1605cm -1 The linear correlation coefficient R between its concentration and Raman intensity 2 It is 0.98992. For CRV, at 1371cm -1 The linear correlation coefficient R between its concentration and Raman intensity 2 It is 0.99514, at 1621cm -1 The linear correlation coefficient R between its concentration and Raman intensity 2 It is 0.99083. For R6G, at 1360cm... -1 The linear correlation coefficient R between its concentration and Raman intensity 2 It is 0.98944, at 1647cm -1 The linear correlation coefficient R between its concentration and Raman intensity 2 The value is 0.98943. The sample exhibits a low detection limit and good linearity for Raman detection of a pair of common pigments and dyes, demonstrating strong application value.

[0076] See Figures 10-13 Nine hundred detection points were randomly selected on sample one, and Raman intensity was measured before and after the addition of DEHP. Before the addition of DEHP, the relative standard deviation (RSD) of the Raman intensity on sample one was 3.63%, 3.44%, and 4.20% for the D peak, G peak, and 2D peak, respectively. Ten... -4 DEHP of M was added to sample one, and the relative standard deviation (RSD) of the Raman intensity on sample one was at 1039 cm⁻¹. -1 1349cm -1 1600cm -1 These correspond to 4.01%, 3.66%, and 3.30%, respectively. This fully demonstrates the homogeneity and stability of Sample 1, and the test results have a high degree of reliability.

[0077] See Figure 14 Add 10 drops to sample one. -4 The EB, R6G, and CRV of M all showed good consistency in different parts of Sample 1, which fully demonstrates the homogeneity of Sample 1.

[0078] See Figure 15 ,exist Figure 14On the basis of the above, the process of rinsing with water and dropping EB, R6G and CRV was repeated, and EB, R6G and CRV were dropped for a total of 5 times. It can be seen that after each rinsing and dropping EB, R6G and CRV, the Raman spectrum has almost no change, which also shows that the water contact angle characteristics of the surface of the sample one has very strong reusability and stability.

[0079] Referring to Figure 16 After DEHP diluted by methanol was dropped on the sample one, it showed five characteristic peak positions of 1039 cm -1 , 1155 cm -1 , 1349 cm -1 , 1445 cm -1 and 1599 cm -1 . The R 2 at 1349 cm -1 and 1599 cm -1 was 0.9957 and 0.9935, respectively. Referring to Figure 17 After 30 days and 5 times of repeated rinsing and dropping DEHP diluted by methanol, the Raman intensity of the sample one did not change significantly.

[0080] Referring to Figure 18 The purchased perfume was diluted by alcohol and dropped on the sample one to detect DEHP in the perfume. With the increase of the degree of dilution, the Raman intensity at 1349 cm -1 and 1599 cm -1 gradually decreased, and the detection concentration limit was as low as 0.01%. The R 2 at 1349 cm -1 and 1599 cm -1 of the sample one for the diluted perfume was 0.9672 and 0.9805, respectively. This fully shows that the sample one can be used to detect DEHP in the market perfume.

[0081] Referring to Figure 19 and Figure 20 After 30 days, the Raman intensity of the sample one for DEHP detection did not change significantly, and after multiple rinsing and repeated dropping of the diluted perfume, the surface structure and Raman spectrum of the sample one did not change significantly, which shows that the sample one can be fully applied to the field of commercial plasticizer detection.

[0082] In order to verify the influence of T2 on the final graphene in step 104, comparative example 3 and comparative example 4 were specially set.

[0083] Comparative example 3:

[0084] The difference between the present comparative example and example 1 is that T2 = 650℃, to prepare sample four.

[0085] Comparative example 4:

[0086] The difference between the present comparative example and example 1 is that T2 = 800℃, to prepare sample five.

[0087] Referring to Figure 21 and Figure 22 , under the condition of deviating from 750℃, it is difficult for graphene to form a spherical structure, and its surface also does not exhibit obvious flower cluster structure at the scale of 1 μm, which exhibits completely different morphological characteristics from sample one, thereby proving that T2 = 750℃ is crucial for the synthesis of the special morphology of sample one, which is contrary to the general cognition in the art.

[0088] Further, in step 105, the volume flow ratio of methane and ammonia is also crucial. Methane can regulate the pore size and distribution in the spherical flower cluster, change the formation rate and density of the pores. Ammonia can affect the roughness of the surface of the spherical flower cluster, the formation of nanostructure and the arrangement of the crystal lattice.

[0089] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the present disclosure.

[0090] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of variations and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A method for controlling the morphology of graphene, characterized in that, The method comprises the following steps: placing a substrate in a quartz tube and vacuumizing the quartz tube; introducing hydrogen and argon into the quartz tube and heating the quartz tube to T1, wherein 600℃≥T1≥500℃; stopping the introduction of hydrogen and argon into the quartz tube, starting a plasma source, and starting the introduction of methane to grow a graphene base on the substrate; turning off the plasma source and stopping the introduction of methane; heating the quartz tube to T2, wherein 800℃≥T2≥700℃, and then starting the simultaneous introduction of methane and ammonia, starting the plasma source and increasing the power to P, wherein P≥200W, so as to transform the graphene base into a flower-like graphene.

2. The graphene morphology control method of claim 1, wherein, During the transformation of the graphene base into the flower-like graphene, the volume flow ratio of the methane and ammonia is 15:

1.

3. The graphene morphology control method of claim 2, wherein, T2=750℃ and P=250W.

4. The graphene morphology control method of claim 3, wherein, The growth time of the graphene base is 60 minutes, the power of the plasma source during the growth is 200W, and the volume flow of the methane is 15sccm.

5. A SRRS film, characterized by, The method comprises using the flower-like graphene prepared by the graphene morphology control method according to any one of claims 1-4.

6. A detection application of the SRRS film according to claim 5, characterized in that, The method is used for detecting one or more of DBP, DEHP, DNDP, EB, R6G and CRV.

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