CN116678870A - Reusable Raman enhanced substrate, preparation method and cleaning method - Google Patents
Reusable Raman enhanced substrate, preparation method and cleaning method Download PDFInfo
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- CN116678870A CN116678870A CN202310866447.6A CN202310866447A CN116678870A CN 116678870 A CN116678870 A CN 116678870A CN 202310866447 A CN202310866447 A CN 202310866447A CN 116678870 A CN116678870 A CN 116678870A
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- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract description 20
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- JQMFQLVAJGZSQS-UHFFFAOYSA-N 2-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]-N-(2-oxo-3H-1,3-benzoxazol-6-yl)acetamide Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)CC(=O)NC1=CC2=C(NC(O2)=O)C=C1 JQMFQLVAJGZSQS-UHFFFAOYSA-N 0.000 description 1
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- PQQKPALAQIIWST-UHFFFAOYSA-N oxomolybdenum Chemical compound [Mo]=O PQQKPALAQIIWST-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
- G01N21/65—Raman scattering
- G01N21/658—Raman scattering enhancement Raman, e.g. surface plasmons
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- Health & Medical Sciences (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
Abstract
The invention belongs to the technical field of Raman spectrum detection, and particularly relates to a reusable Raman enhancement substrate, a preparation method and a cleaning method, wherein molybdenum acetylacetonate is used as a raw material to prepare molybdenum dioxide nano particles through hydrothermal reaction, the molybdenum dioxide nano particles are dispersed in water to form molybdenum dioxide aqueous dispersion, the molybdenum dioxide aqueous dispersion is dripped on a substrate to prepare the molybdenum dioxide substrate through drying, the molybdenum dioxide substrate prepared by the invention has excellent Raman enhancement effect and excellent photo-thermal conversion efficiency and thermal conductivity, the surface temperature of the molybdenum dioxide substrate can reach 200-400 ℃ under the radiation of near infrared laser or a xenon lamp, the thermal decomposition removal of small molecules is realized, the purpose of cleaning and recycling the molybdenum dioxide substrate is achieved, and after 5 cycle tests, moO is realized 2 The substrate still has excellent raman enhancing effect and maintains stability of its structure.
Description
Technical Field
The invention belongs to the technical field of Raman spectrum detection, and particularly relates to a reusable Raman enhanced substrate, a preparation method and a cleaning method.
Background
Surface Enhanced Raman Spectroscopy (SERS) as a convenient, sensitiveAnd nondestructive analysis technology, can provide fingerprint spectrum information of molecular structure vibration, and has wide application prospect in aspects of food safety, environmental pollutant monitoring, life science, chemical and biological sensing and the like. Currently, SERS enhancement has two main mechanisms: electromagnetic Enhancement (EM) and chemical enhancement (CM). The electromagnetic mechanism is based on Local Surface Plasmon Resonance (LSPR) effect excited by incident light on rough metal surface, local magnetic field amplification around metal, and improves radiation efficiency of probe molecule oscillating dipole source, and electromagnetic enhancement can generally improve signal intensity of analyte by 10 5 ～10 6 Multiple times. Chemical enhancement is then the chemical interaction between the substrate and the probe molecule.
Noble metal materials are often used as SERS active substrates due to their strong LSPR effect. For example: au nanoparticles are currently commonly used SERS substrates because of their very strong LSPR effect. However, the gold nano material has the problems of high manufacturing cost, strong spectrum background, poor biocompatibility, low reproducibility and the like, and severely restricts the application of the gold nano material in SERS. Ag nanoparticles are another widely studied SERS substrate material that, although much cheaper than Au, is susceptible to sulfidation by sulfur-containing compounds or oxidation by laser irradiation with raman spectroscopy in the environment. In recent years, the discovery of certain novel LSPR active metal oxides (e.g., oxygen vacancy-rich non-stable stoichiometric semiconductor oxides, such as WO 2.83 Nanorods, tiO 2-x Nanoplatelets, moO 3-x Nanoparticles, etc.), whose LSPR effect is produced by oxygen vacancies contained in the crystal lattice, enriches the species of raman-enhanced substrates to some extent. However, these substrates currently suffer from the common phenomenon that the analyte remains on the substrate surface after detection, combined with instability in the structure of the substrate itself, such as MoO 3-x After high temperature treatment or acid-base soaking, oxygen vacancies are destroyed, even when the sample is placed for a period of time at room temperature, the oxygen in the air is oxidized, the valence state of the sample is changed, the sample is unstable, namely the stability of the structure is difficult to maintain, and the substrate is difficult to reuse due to the residue of the substrate surface detection substance and the instability of the substrate structure.
The current method for realizing the reusability of the Raman enhanced substrate mainly comprises the following two methods:
(1) Photodegradation: the noble metal and the semiconductor with photocatalysis performance are compounded to form a substrate, and dye molecules adsorbed on the surface of the substrate are eliminated through photocatalysis to realize self-cleaning of the substrate. However, the light absorption section of the traditional semiconductor catalyst is generally smaller, the spectral response range is narrow, the number of photons which can be captured and utilized is very limited, and the degradation efficiency of a high-efficiency photocatalytic system is greatly hindered, so that the photocatalytic degradation time is generally longer, and the catalyst is easily influenced by temperature, pH value, surface defects and the like in the catalytic process, so that the catalytic activity is reduced or inactivated to further influence the subsequent detection experiment.
(2) And (3) cleaning a solvent: dispersing the detected substrate in acid ethanol for ultrasonic treatment, centrifuging to collect a sample, and repeating the steps for several times until dye molecules are completely removed. In the method, hydrochloric acid is needed to be used in the cleaning process of part of probe molecules, the hydrochloric acid is a management and control medicine which is easy to prepare and has certain corrosion capability, certain danger exists in the experimental operation process, and a substrate is needed to be prepared again for detection after the sample is collected. In addition, the acidic ethanol is adopted for cleaning, so that the structural stability of a base sample in the cleaning process is required to be ensured, the selection of the substrate is limited to a certain extent, and the acidic waste liquid generated in the cleaning process can pollute the environment to a certain extent.
Therefore, in order to solve the problems of the existing raman enhancement substrate, it is necessary to develop a recyclable substrate with high sensitivity, high stability, low cost and good versatility.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention aims to provide a reusable Raman enhanced substrate, a preparation method and a cleaning method, and the nano MoO prepared by the invention 2 The flower-shaped or dumbbell-shaped nanospheres have excellent photo-thermal conversion efficiency and heat radiation stability, and the nano MoO provided by the invention 2 The surface temperature of the prepared Raman enhanced substrate can reach 200-400 ℃ under the radiation of near infrared laser or xenon lamp, and the temperature exceeds the molecular weight of most small moleculesThe solution temperature reaches the effect of cleaning the surface of the substrate, and the substrate is reused; and the substrate has good structural stability at the temperature, and still shows excellent Raman enhancement effect after repeated cyclic tests.
Based on the above purpose, the technical scheme adopted by the invention is as follows:
in a first aspect, the present invention provides a method for preparing a reusable raman-enhanced substrate, comprising the steps of:
s1: nanometer MoO 2 Is prepared from
Dissolving molybdenum acetylacetonate in ethanol water solution to form a precursor solution; carrying out hydrothermal reaction on the precursor solution, centrifuging to collect precipitate after the reaction, and then washing and drying to obtain the nano MoO 2 ；
S2: preparation of reusable raman-enhanced substrates
Nanometer MoO prepared in the step S1 2 MoO of 1-5 mg/mL 2 Aqueous dispersion of MoO 2 The aqueous dispersion is dropped on a substrate and dried to prepare MoO 2 The substrate is the reusable Raman enhanced substrate.
The nano molybdenum dioxide prepared by the method of the invention is flower-shaped or dumbbell-shaped nanospheres, the surface of which is rough and full of sharp protrusions, the surface-rough nanospheres are composed of a plurality of small nano sheets, the sizes of which are about 10-20 nm, which are mutually piled to form flower-shaped or dumbbell-shaped nanospheres, the rough surface and a plurality of pores are advantageous characteristics of SERS substrate structures, because the sharp protrusions and the gaps of nano scale can significantly enhance local electromagnetic field intensity and provide a plurality of active 'hot spots'. The molybdenum dioxide substrate prepared from the nano molybdenum dioxide has a strong Raman enhancement effect, the surface temperature of the molybdenum dioxide substrate can reach 200-400 ℃ under the radiation of near infrared laser or a xenon lamp, the organic micromolecule can be thermally decomposed and removed for surface purification, and the molybdenum dioxide substrate can still maintain the structural stability after being subjected to high-temperature treatment, laser irradiation or acid-base soaking, and can be recycled.
Experiments show that in the nano MoO of the invention 2 In the concentration range of the aqueous dispersion, a layer of nano molybdenum dioxide can be paved on the substrate, and the Raman detection requirement can be met.
Preferably, the ethanol content of the ethanol aqueous solution in the step S1 is 18% -80% (v/v).
Preferably, the concentration of the molybdenum acetylacetonate in the precursor solution is 2-6 mg/mL.
Experiments show that the variation of the molybdenum acetylacetonate in the precursor solution within the solubility range has little influence on the appearance of the molybdenum dioxide and the performance of the finally prepared molybdenum dioxide substrate. The content of the ethanol in the ethanol aqueous solution has great influence on the morphology of the nano molybdenum dioxide, the nano flower-like spherical or dumbbell-shaped spherical molybdenum dioxide can be obtained only when the ratio of the ethanol to the water is proper, and the molybdenum dioxide substrate prepared from the nano flower-like spherical or dumbbell-shaped spherical molybdenum dioxide shows better detection sensitivity.
Preferably, the temperature of the hydrothermal reaction in the step S1 is 180-200 ℃ and the reaction time is 12-16 h.
Preferably, in the step S1, molybdenum acetylacetonate is dissolved in an ethanol aqueous solution in a stirring state to form a precursor solution, wherein the stirring speed is 500-600 r/min, and the stirring time is 24-48 h.
Preferably, the cleaning in step S1 includes the steps of: and centrifugally cleaning the centrifugally collected precipitate for 5-10 min at 8000-15000r/min by using absolute ethyl alcohol, and then centrifugally cleaning the precipitate for 10-15 min at 8000-15000r/min by using water for at least 3 times.
Preferably, the substrate is a cover glass or a silicon wafer.
In a second aspect, the present invention provides a reusable raman-enhanced substrate made by the above method.
In a third aspect, the present invention provides a method for cleaning and recycling a raman-enhanced substrate, comprising the steps of:
and (3) carrying out near infrared laser irradiation or xenon lamp irradiation on the Raman enhanced substrate until the surface temperature reaches 200-400 ℃, and carrying out thermogravimetric analysis to ensure that molybdenum dioxide shows good thermal stability within 700 ℃, so that the surface temperature of the molybdenum dioxide substrate is controlled within 700 ℃ by controlling the laser irradiation power and irradiation time, and the aim of carrying out thermal decomposition and removal on the compound on the surface of the molybdenum dioxide substrate is fulfilled while the structure of the molybdenum dioxide is kept stable, thereby realizing the recycling of the molybdenum dioxide substrate.
Preferably, near infrared laser with 808nm wavelength and laser power density of 0.75-2W/cm 2 The irradiation time is 5-20 min.
Preferably, the raman-enhanced substrate is placed in Ar/N 2 Near infrared laser irradiation or xenon lamp irradiation is performed in atmosphere or air.
Compared with the prior art, the invention has the following beneficial effects:
the molybdenum dioxide nano-particles are prepared by taking molybdenum acetylacetonate as a raw material through hydrothermal reaction, and the prepared molybdenum dioxide nano-particles are in a nano-flower sphere-like shape or a dumbbell-shaped sphere-like shape, have excellent chemical, thermal and radiation stability, the area near the fermi level consists of Mo 3d orbitals, a large number of free electrons in the d orbitals enable the molybdenum dioxide nano-particles to show metal characteristics, and the high free electron density enables MoO 2 Molybdenum dioxide exhibits a localized surface plasmon resonance effect (LSPR) similar to that of metallic materials, with more metallic rather than semiconducting properties.
The nanometer MoO of the invention 2 Instead of the LSPR effect of the semiconductor oxide being generated by oxygen vacancies contained in the crystal lattice (e.g. TiO) 2-x ，MoO 3-x ) Compared with the semiconductor oxide, the MoO prepared by the invention 2 The stability of the nanospheres is more excellent, and the nanospheres have higher application value.
In addition, the nanometer MoO of the invention 2 The electrons vibrating in the middle convert kinetic energy into heat energy due to damping effect, local heat is increased, and the temperature of the metal material is increased and spread to the periphery through heat conduction, so that MoO 2 The surface temperature of the molybdenum dioxide substrate can reach 200-400 ℃ under the radiation of near infrared laser or xenon lamp, and the temperature exceeds most small moleculesThe test shows that after about 10 minutes of laser radiation, the surface adsorption molecules are completely removed, and after 5 cycle tests, moO 2 The substrate still has excellent raman enhancement effect and can maintain structural stability.
In conclusion, the molybdenum dioxide substrate prepared by the method has a strong Raman enhancement effect and excellent structural stability, and can achieve the effect of purifying the surface of the molybdenum dioxide substrate through short-time laser irradiation, so that the recycling of the molybdenum dioxide substrate is realized.
Drawings
FIG. 1 is a nano flower sphere MoO of example 1 2 Is a preparation flow chart of (2);
FIG. 2 is a nano flower-like spherical MoO prepared in example 1 2 Electron microscope pictures and sample characterization;
FIG. 3 is a nano MoO prepared in example 1 2 Stability testing of (2);
FIG. 4 shows the nano MoO prepared in example 2 2 A raman enhancement schematic of the substrate;
FIG. 5 is a blank substrate and MoO of example 2 2 Raman signals of different probe molecules on the substrate;
FIG. 6 is a nano MoO in example 3 2 At N 2 Thermal gravimetric curves of dye molecules in air, moO 2 And temperature change curves of the blank substrate at different laser power densities;
FIG. 7 is a graph showing the Raman signal change during an opto-erasable process for dye molecules of example 3;
FIG. 8 is a variation of R6G Raman signal in the light-erasable cycle of example 4;
FIG. 9 is a variation of R6G/RhB/MB/CV Raman signal over the light-erasable cycle of example 5;
FIG. 10 is a schematic illustration of MoO after light-erasable cycling of example 5 2 Electron microscope pictures and sample characterization;
FIG. 11 is a graph of the morphology of the sample and the Raman signal of R6G at different ratios in example 6;
FIG. 12 is a graph showing the morphology of samples and the Raman signal of R6G for different amounts of precursor in example 7;
FIG. 13 shows the laser power density of 0.75W/cm for example 8 2 Changes in R6G raman signal during photo-erasable;
FIG. 14 shows the laser power density of 1W/cm for example 9 2 Changes in R6G raman signal during photo-erasable;
FIG. 15 shows the laser power density of 2W/cm for example 10 2 Changes in R6G raman signal during photo-erasable;
FIG. 16 is a schematic diagram of the scanning electron microscope image and the Raman detection effect of the product of comparative example 1;
FIG. 17 is a comparative example 2MoO 2 A scanning electron microscope picture and a Raman detection effect schematic diagram;
FIG. 18 shows that the laser power density of comparative example 3 is 0.5W/cm 2 Changes in R6G raman signal during photo-erasable;
FIG. 19 is a schematic representation of the drop-on of 10. Mu.L 10 on a blank substrate of comparative example 4 -4 R6G/RhB/MB/CV dye molecular light irradiation of M is shown before and after schematic drawing.
Detailed Description
For a better description of the objects, technical solutions and advantages of the present invention, the present invention will be further described with reference to the following specific examples. It will be appreciated by persons skilled in the art that the specific embodiments described herein are for purposes of illustration only and are not intended to be limiting. The test methods used in the examples are conventional methods unless otherwise specified; the materials, reagents and the like used, unless otherwise specified, are all commercially available.
Example 1
This example provides a method for preparing a flower-like spherical MoO 2 The preparation process is shown in figure 1, and comprises the following steps:
weighing 0.1g of molybdenum acetylacetonate, grinding in a mortar for 10-20 minutes, sequentially adding 41mL of deionized water and 9mL of absolute ethyl alcohol after finishing grinding, controlling the ratio of the deionized water to the absolute ethyl alcohol to be about 4:1, stirring for 24-48 hours, setting the rotating speed to be 500-600 r/min, transferring the dissolved precursor liquid into a 100mL polytetrafluoroethylene reaction kettle for hydrothermal reaction, wherein the temperature in the hydrothermal process is 180 ℃, and the hydrothermal time is 12-16 hours.
Centrifugally cleaning the product after the hydrothermal reaction by using absolute ethyl alcohol and deionized water respectively, and centrifugally cleaning the product by using absolute ethyl alcohol for three times, wherein the rotational speed of centrifugal cleaning is 8000-15000r/min each time, and the cleaning time is 5-10 min; and centrifugal washing with deionized water for three times, wherein the rotational speed of centrifugal washing is 8000-15000r/min and the washing time is 10-15 min.
Drying the cleaned sample in a vacuum oven at 60-80 ℃ for 3-8 h, and collecting the sample to obtain the nano MoO 2 。
For the nanometer MoO prepared by the method 2 Performance testing was performed as shown in fig. 2 and 3, wherein fig. 2a is MoO 2 FIG. 2b is a scanning electron microscope image of MoO 2 Is transmitted by a transmission electron microscope picture, and the nanometer MoO is prepared 2 The sample takes the form of flower-like nanospheres, with a rough surface and filled with sharp protrusions. The high power scanning electron microscope image further shows that the nanospheres with rough surfaces are composed of a plurality of small nano-sheets, the sizes of the nano-sheets are about 10-20 nm, and the nano-sheets are mutually piled to form flower-shaped nanospheres. Rough surfaces and large numbers of voids are advantageous features of SERS substrate structures because sharp protrusions and nano-scale gaps will significantly enhance local electromagnetic field strength and provide a large number of active "hot spots". FIG. 2c is MoO 2 The diffraction pattern of the nanospheres showed 6 narrow and sharp peaks at 26.3 °, 37.1 °, 41.6 °, 53.9 °, 60.9 ° and 67.0 °, corresponding to MoO, respectively 2 The (110), (101), (111), (211), (301) and (002) planes of (PDF # 32-0671), these characteristic diffraction peaks reflect the high crystallinity of the product. FIG. 2d is MoO 2 Raman spectrum, moO of (a) 2 Is shown at 121, 196, 220, 354, 488, 564 and 728cm -1 There are typical characteristic peaks. 564 and 728cm -1 The characteristic peak at the location can be attributed to MoO 2 The O-Mo bond vibration modes of 121, 196, 220, 354 and 488cm -1 The characteristic peak at the location can be attributed to MoO 2 Phonon vibration modes of (a).
FIG. 3a is MoO 2 Has a distinct absorption peak around 800 nm. Such absorption peaks are typical of localized surface plasmon resonance characteristics. FIGS. 3 b-3 d show MoO 2 Chemical, thermal, radiation stability test patterns of (c). After high temperature treatment, laser irradiation and acid-base soaking, moO 2 The nanospheres showed no significant change in localized surface plasmon resonance absorption peak (LSPR), showing high stability.
Example 2
This example provides a method for preparing a reusable raman-enhanced substrate using the molybdenum dioxide nanoparticles prepared in example 1, comprising the steps of:
weighing a certain amount of nano MoO prepared in example 1 2 Mixing with deionized water to prepare MoO with the concentration of 1-5 mg/mL 2 An aqueous dispersion. Taking 10-50 mu L MoO by a pipetting gun 2 Dispersing liquid drop on substrate, which can be cover glass, silicon chip or other common substrate, and oven drying at 60deg.C to obtain MoO 2 A substrate.
In this example, rhodamine 6G (R6G), rhodamine B (RhB), methylene Blue (MB) and Crystal Violet (CV) were used as probe molecules, and the Raman enhanced substrate (MoO) prepared in this example was analyzed 2 A substrate).
Weighing a certain amount of four probe molecules respectively to prepare the probe molecules with the concentration of 10 -3 M mother liquor, and the mother liquor is diluted in sequence to obtain the concentration of 10 -4 、10 -5 、10 -6 、10 -7 M, four probe molecule detection solutions. Prepared MoO with a pipette 2 50-100 mu L of the four different dyes are respectively dripped on the substrate, and the concentration of dye molecules is respectively 10 -4 ～10 -7 M, then put in an oven at 60 ℃ for drying. And after the sample is dried, 532nm laser is selected for Raman detection.
MoO 2 The raman enhancement of the substrate is schematically shown in fig. 4, where incident light excites Localized Surface Plasmon Resonance (LSPR) effects on the metal surface, and the electromagnetic field is concentrated on the metal surface, resulting in the creation of surface enhancement effects. When the sample interacts with such surface enhancing effects, it is possible toTo generate strong raman scattering signals to achieve very high sensitivity detection of the sample.
FIGS. 5a, 5b, 5c, 5d are the blank substrate and MoO, respectively 2 As can be seen from FIG. 5, the Raman signals of different probe molecules on the substrate, on the blank substrate, the probe molecules are not detected, on MoO 2 A concentration of 10 was detected on the substrate -7 M probe molecule, indicating MoO prepared according to the present invention 2 The substrate has a raman enhancing effect.
Example 3
This example shows that the concentration of R6G after detection in example 2 is 10 -4 MoO of M 2 The substrate is exemplified by a cleaning and recycling method of the raman-enhanced substrate according to the present invention, which is based on "photo-erasable" removal of adsorbed molecules on the surface of the substrate, comprising the steps of:
the concentration of R6G after detection in example 2 was 10 -4 MoO of M 2 The substrate is irradiated under 808nm near infrared laser with the laser power density of 1.5W/cm 2 In Ar/N 2 Irradiation in atmosphere was performed every 2.5 minutes, i.e., the substrate with irradiation time of 0,2.5,5,7.5 and 10 minutes was inspected, and the change of R6G signal was observed, and it was found that the R6G signal of the probe molecule disappeared by irradiation with laser light for about 10 minutes, indicating MoO 2 The probe molecules adsorbed on the surface of the substrate have been removed.
FIG. 6a is MoO 2 Temperature profiles of the substrate and blank substrate at different laser power densities. As shown in the figure, the temperature change of the blank substrate is not obvious under the irradiation of the near infrared laser, while MoO 2 The surface temperature of the laser beam is gradually increased along with the increase of the laser power density, and the laser power is 2W/cm 2 When the surface temperature of the molybdenum dioxide reaches 400 ℃, the surface temperature of the molybdenum dioxide can be further improved along with the increase of the laser power density. FIG. 6b is MoO 2 At N 2 Thermal weight curve in (1), at N 2 MoO under atmosphere 2 Can be kept stable at 300-700 ℃. FIG. 6c, FIG. 6d, FIG. 6e, FIG. 6f are thermal re-entrant of R6G, rhB, MB, CV dye molecules in air, respectivelyThe line, at around 200 ℃, the dye starts to decompose.
From a combination of FIGS. 6a to 6f, it can be seen that the temperature change of the blank substrate is not obvious under the irradiation of the near infrared laser, but MoO 2 The surface temperature of (2) may reach 400 ℃, which is a temperature above the decomposition temperature of most dye molecules and at N 2 MoO under atmosphere 2 Can keep stable structure between 300 ℃ and 700 ℃. In summary, we propose a light-erasable implementation of MoO 2 A method for reusing a substrate.
FIG. 7a shows the variation of R6G Raman signal during irradiation, FIG. 7b shows the variation of R6G during irradiation 1 614 cm -1 、R 2 774 cm -1 、R 3 1360 cm -1 、R 4 1651 cm -1 The signal of R6G disappeared at about 7.5 minutes due to the change in intensity. The method for cleaning the substrate and performing photocatalytic degradation to realize recycling of the substrate generally needs a longer time, for example, photocatalytic degradation is generally performed for more than 2 hours, so that the raman-enhanced substrate can realize self-cleaning of the surface in a short time in the prior art.
Example 4
This example is directed to analysis of MoO made in example 2 2 Stability of the recycling performance of the substrate, the specific test method is as follows:
at MoO with a pipette 2 Dropwise adding 10 mu L of 10 to a substrate -4 And (3) drying the dye molecules of M in an oven at 60 ℃, and carrying out Raman detection on the substrate with the dye molecules adsorbed on the surface, wherein 532nm laser is selected in the detection process. The concentration of R6G after detection is 10 -4 The M substrate is irradiated under 808nm near infrared laser for 10 minutes, and the laser power density is 1.5W/cm 2 In Ar/N 2 After the irradiation was completed, the Raman detection was performed by laser light of 532nm in the atmosphere, and no R6G signal was observed.
MoO after laser irradiation with a pipette 2 10 mu L of 10 are added dropwise to the substrate -4 M, then drying in oven at 60deg.C, pulling with 532nm laserMannich detection, the signal of R6G is observed, and the concentration of R6G after detection is 10 -4 The M substrate is irradiated under 808nm near infrared laser for 10 minutes, and the laser power density is 1.5W/cm 2 In Ar/N 2 After the irradiation was completed, the Raman detection was performed by laser light of 532nm in the atmosphere, and no R6G signal was observed. The above cycle was repeated 5 times.
FIG. 8a shows the variation of R6G Raman signal during 5 cycles and FIG. 8b shows the variation of R6G at 614cm during 5 cycles -1 、774cm -1 、1360cm -1 、1651cm -1 Change in intensity. Fig. 8c is a light-erasable cycling process. The SERS spectra of R6G were very similar during each cycle of detection, with R6G at 614, 778, 1360 and 1651cm over 5 consecutive cycles of detection and decomposition -1 The intensity of the corresponding peak at the position is not changed greatly, and the display substrate has excellent reusable property.
Example 5
The detection sensitivity of the molybdenum dioxide substrate purified by laser irradiation is analyzed, and the specific test method is as follows:
at MoO with a pipette 2 Dropwise adding 10 mu L of 10 to a substrate -4 The R6G dye molecules of M are then dried in an oven at 60 ℃. And carrying out Raman detection on the substrate with dye molecules adsorbed on the surface, wherein 532nm laser is selected in the detection process. The concentration of R6G after detection is 10 -4 The M substrate is irradiated under 808nm near infrared laser for 10 minutes, and the laser power density is 1.5W/cm 2 In Ar/N 2 The above cycle was repeated 5 times by irradiation in the atmosphere.
MoO with pipette cycling 5 times above 2 50 mu L of 10 is dripped on the substrate -4 The R6G dye molecules of M are then dried in an oven at 60 ℃. And carrying out Raman detection on the substrate with the probe molecules adsorbed on the surface, wherein 532nm laser is selected in the detection process. The concentration of R6G/RhB/MB/CV after detection is 10 -4 The M substrate is irradiated under 808nm near infrared laser for 10 minutes, and the laser power density is 1.5W/cm 2 In Ar/N 2 After the irradiation was completed, the Raman detection was performed by laser light of 532nm in the atmosphere, and no R6G signal was observed.
At MoO with a pipette 2 The substrate was further added dropwise with 50. Mu.L of 10 -5 The R6G dye molecules of M are then dried in an oven at 60 ℃. And carrying out Raman detection on the substrate with the probe molecules adsorbed on the surface, wherein 532nm laser is selected in the detection process. The concentration of R6G after detection is 10 -5 The M substrate is irradiated under 808nm near infrared laser for 10 minutes, and the laser power density is 1.5W/cm 2 In Ar/N 2 After the irradiation was completed, the Raman detection was performed by laser light of 532nm in the atmosphere, and no R6G signal was observed.
At MoO with a pipette 2 The substrate was further added dropwise with 50. Mu.L of 10 -6 The R6G dye molecules of M are then dried in an oven at 60 ℃. And carrying out Raman detection on the substrate with the probe molecules adsorbed on the surface, wherein 532nm laser is selected in the detection process. The concentration of R6G after detection is 10 -6 The M substrate is irradiated under 808nm near infrared laser for 10 minutes, and the laser power density is 1.5W/cm 2 In Ar/N 2 After the irradiation was completed, the Raman detection was performed by laser light of 532nm in the atmosphere, and no R6G signal was observed.
At MoO with a pipette 2 The substrate was further added dropwise with 50. Mu.L of 10 -7 The R6G dye molecules of M are then dried in an oven at 60 ℃. And carrying out Raman detection on the substrate with the probe molecules adsorbed on the surface, wherein 532nm laser is selected in the detection process. The concentration of R6G after detection is 10 -7 The M substrate is irradiated under 808nm near infrared laser for 10 minutes, and the laser power density is 1.5W/cm 2 In Ar/N 2 After the irradiation was completed, the Raman detection was performed by laser light of 532nm in the atmosphere, and no R6G signal was observed.
With reference to the above method, R6G is replaced by dye molecule RhB, MB, CV, and in the course of the above cyclic experiment, the change of R6G, rhB, MB, CV Raman signal is as shown in FIG. 9a, FIG. 9b, FIG. 9c and FIG. 9d, after laser irradiation, R6G/RhB/MB/CV signal disappears, low concentration R6G/RhB/MB/CV dye is added dropwise again, R6G/RhB/MB/CV signal can still be detected, and the lowest cyclic detection of 10 is possible -7 M, thus, the molybdenum dioxide substrate of the invention still detects dye molecules and the like after being washed for many timesThe article has 10 -7 Detection sensitivity of M.
FIG. 10a shows MoO after 5 cycles of detection 2 FIG. 10b is a scanning electron microscope image of MoO after 5 cycles of detection 2 FIG. 10c shows the MoO after 5 cycles of detection 2 Figure 10d shows MoO after 5 cycles of detection 2 Is provided. As shown in fig. 10, the morphology of the sample was not significantly changed, and sharp protrusions were still present. After circulation, moO 2 The XRD and Raman spectra of the substrate are not changed obviously, and the stability of the molybdenum dioxide base is further confirmed.
Example 6
The embodiment aims at exploring the influence of different molybdenum dioxide preparation methods on the Raman enhancement performance of the prepared molybdenum dioxide substrate, and the specific test method is as follows:
weighing 0.1g of molybdenum acetylacetonate, grinding in a mortar for 10-20 minutes, sequentially adding deionized water and absolute ethyl alcohol after finishing grinding, and changing the proportion of the deionized water to the absolute ethyl alcohol, wherein the proportion of the deionized water to the absolute ethyl alcohol is respectively 10mL:40mL, 20mL:30mL, 30mL:20mL and 25mL. Stirring for 24-48 h at 500-600 r/min, transferring the dissolved precursor liquid into a 100mL polytetrafluoroethylene reaction kettle for hydrothermal reaction, wherein the temperature in the hydrothermal process is 180 ℃, and the hydrothermal time is 12-16 h, so as to prepare the molybdenum dioxide.
Weighing a certain amount of molybdenum dioxide prepared from the 4 deionized water and ethanol in the ratios of 10mL to 40mL, 20mL to 30mL, 30mL to 20mL and 25mL to 25mL respectively, and mixing MoO with the mixture of the deionized water and ethanol 2 Mixing with deionized water to prepare MoO with concentration of 5mg/mL 2 Mother liquor. 10 mu LMoO was removed by pipetting gun 2 Dispersing the liquid drops on a substrate, and then drying in an oven at 60 ℃ to obtain four MoOs 2 A substrate.
Prepared 4 MoOs with a pipette 2 100 mu L of 10 are respectively dripped on the substrate -7 The R6G dye molecules of M are then dried in an oven at 60 ℃. After the sample is dried, 532nm laser is selected for Raman detection, and experiments show that molybdenum dioxide base prepared by the four proportionsAll can detect 10 on the bottom -7 MR6G dye molecules.
The concentration of R6G after detection is 10 -7 The M substrate is irradiated under 808nm laser for 10 minutes, and the laser power density is 1.5W/cm 2 In Ar/N 2 After the irradiation was completed, the Raman detection was performed by laser light of 532nm in the atmosphere, and no R6G signal was observed. At MoO with a pipette 2 100 mu L of 10 was again added dropwise to the substrate -7 M dye molecules were then dried in an oven at 60℃and Raman detected with 532nm laser to re-detect the R6G signal.
Fig. 11a to 11d are respectively morphology graphs of molybdenum dioxide samples under four different ethanol and water ratios, and fig. 11e to 11f are respectively raman signal changes of the molybdenum dioxide substrate detection samples under four different ratios. MoO with the change of the volume ratio of deionized water to ethanol 2 The morphology and aggregation state of (c) also change. When the ratio of deionized water to ethanol is 10mL to 40mL, moO 2 Is obvious in agglomeration and irregular in morphology. MoO is carried out when the ratio of deionized water to ethanol is changed to 20mL to 30mL and 30mL to 20mL respectively 2 Is gradually weakened. When the ratio of deionized water to ethanol is 25mL to 25mL, moO 2 The dispersion is obvious. In conclusion, the ratio of deionized water to ethanol is equal to MoO 2 The morphology and aggregation state of the molybdenum oxide are affected, but the volume ratio of deionized water to ethanol is within a certain range (the ethanol content in the ethanol water solution is 18% -80%), and the influence on the Raman enhancement effect of the prepared molybdenum dioxide and the corresponding substrate is not obvious.
Example 7
The purpose of this example is to explore the effect of the amount of molybdenum acetylacetonate on the molybdenum dioxide and the molybdenum dioxide substrate produced, the specific test method being as follows:
0.3g of molybdenum acetylacetonate is weighed and ground in a mortar for 10-20 minutes, and 41mL of deionized water and 9mL of absolute ethyl alcohol are sequentially added after the grinding is finished. The ratio of deionized water to absolute ethyl alcohol is controlled at about 4:1, the stirring time is 24-48 h, the rotating speed is set at 500-600 r/min, the dissolved precursor liquid is transferred into a 100mL polytetrafluoroethylene reaction kettle for hydrothermal reaction, the temperature in the hydrothermal process is 180 ℃, and the hydrothermal time is 12-16 h, so that molybdenum dioxide is prepared.
Weighing a certain amount of the MoO 2 MoO with deionized water to form the concentration of 1-5 mg/mL 2 Mother liquor. Taking 10-50 mu L MoO by a pipetting gun 2 Dispersing the liquid drop on the substrate, and then drying in an oven at 60 ℃ to obtain MoO 2 A substrate.
Prepared MoO with a pipette 2 100 mu L of 10 is dripped on the substrate -7 The R6G dye molecules of M are then dried in an oven at 60 ℃. After the sample is dried, 532nm laser is selected for Raman detection, and 10 can be detected -7 R6G dye molecules of M.
The concentration of R6G after detection is 10 -7 The M substrate is irradiated under 808nm near infrared laser for 10 minutes, and the laser power density is 1.5W/cm 2 In Ar/N 2 After the irradiation was completed, the Raman detection was performed by laser light of 532nm in the atmosphere, and no R6G signal was observed. At MoO with a pipette 2 100 mu L of 10 was again added dropwise to the substrate -7 M dye molecules were then dried in an oven at 60℃and Raman detected with 532nm laser, again observing the R6G signal.
Fig. 12a is a graph of the morphology of molybdenum dioxide obtained at different amounts of molybdenum acetylacetonate, and fig. 12b is a variation of the R6G raman signal on the molybdenum dioxide substrate. When the dosage of the molybdenum acetylacetonate is increased to 0.3g, the molybdenum dioxide is changed into a dumbbell-shaped nano structure from the flower-shaped nanospheres, and the detection of low concentration can still be realized after the light-wiping, namely, when the dosage of the molybdenum acetylacetonate is changed within a certain range (the concentration of the molybdenum acetylacetonate in an ethanol aqueous solution is 2-6 mg/mL), the detection effect of the molybdenum dioxide substrate is not influenced.
Example 8
A method of "photo-erasable" removal of adsorbed molecules from a surface of a substrate, the method comprising the steps of: the concentration of R6G after detection is 10 -4 The M substrate is irradiated by 808nm near infrared laser with the laser power of 0.75W/cm 2 The detection was performed every 10 minutes to observe the change in R6G signal. The probe is divided by laser irradiation for about 30 minutesThe sub-signal disappeared, indicating that the surface adsorbed molecules had been removed.
FIG. 13 shows a laser power density of 0.75W/cm 2 Changes in R6G raman signal during light-erasable. After 30-40 minutes of irradiation, the raman signal of R6G disappeared, indicating that the dye molecules were decomposed at the substrate surface. When the laser power density is reduced, the time required for dye decomposition is prolonged, because the surface temperature of the molybdenum dioxide substrate is reduced with the reduction of the laser power density, and the time required for dye decomposition is prolonged correspondingly, so that the thermal decomposition removal time of the molybdenum dioxide substrate surface detection object can be greatly shortened by increasing the power density of laser irradiation.
Example 9
A method of "photo-erasable" removal of adsorbed molecules from a surface of a substrate, the method comprising the steps of: the concentration of R6G after detection is 10 -4 M, the substrate is irradiated under 808nm laser with the power density of 1W/cm 2 In Ar/N 2 The irradiation was performed in the atmosphere, and the change in R6G signal was observed every 5 minutes. The signal of the probe molecule disappears after the laser irradiation for about 20 minutes, which indicates that the molecules adsorbed on the surface have been removed.
FIG. 14 shows a laser power density of 1W/cm 2 Changes in R6G raman signal during light-erasable. After 20 minutes of irradiation, the raman signal of R6G disappeared, indicating that the dye molecules were decomposed at the substrate surface. As the laser power density increases, the time required for dye decomposition also shortens, since as the laser power density increases, the surface temperature of the molybdenum dioxide substrate also increases, and the corresponding time required for dye decomposition shortens.
Example 10
A method of "photo-erasable" removal of adsorbed molecules from a surface of a substrate, the method comprising the steps of: the concentration of R6G after detection is 10 -4 M substrate is placed under 808nm laser with power density of 2W/cm 2 In Ar/N 2 The irradiation was performed in the atmosphere, and the change in R6G signal was observed every 2.5 minutes. The signal of the probe molecule disappears after about 5 minutes of laser irradiation, which indicates the adsorption of the surfaceThe seed has been removed.
FIG. 15 shows a laser power density of 2W/cm 2 Changes in R6G raman signal during light-erasable. After 5 minutes of irradiation, the raman signal of R6G disappeared, indicating that the dye molecules were decomposed at the substrate surface. As the laser power density increases, the time required for dye decomposition also gradually shortens, since as the laser power density increases, the surface temperature of the molybdenum dioxide substrate also increases, and the corresponding time required for dye decomposition shortens.
Comparative example 1
A method for preparing a surface-enhanced raman spectroscopy substrate based on a metal oxide, comprising the following steps: weighing 0.1g of molybdenum acetylacetonate, grinding in a mortar for 10-20 minutes, adding 50mL of deionized water after finishing grinding, stirring for 24-48 hours, setting the rotating speed at 500-600 r/min, transferring the dissolved precursor liquid into a 100mL polytetrafluoroethylene reaction kettle for hydrothermal reaction, wherein the temperature in the hydrothermal process is 180 ℃, and the hydrothermal time is 12-16 hours.
Weighing a certain amount of the product and deionized water to prepare a mother solution with the concentration of 1-5 mg/mL. And (3) taking 10-50 mu L of dispersion liquid drops on the substrate by using a liquid-transferring gun, and then putting the dispersion liquid drops in a baking oven at 60 ℃ to obtain the substrate.
100 μL of 10 was added dropwise to the prepared substrate using a pipette -7 The R6G dye molecules of M are then dried in an oven at 60 ℃. After the sample is dried, 532nm laser is selected for Raman detection, and the detection limit is lower than 10 -7 M。
Fig. 16a is a scanning electron microscope image of the product, and fig. 16b is the SERS detection effect of the product. When deionized water is used as a solvent, the morphology of the sample is greatly changed, the sheet-shaped nano belt is displayed, and the size is in the micron level. At this time, the detection effect of the substrate is greatly influenced by the morphology, and the detection limit is lower than 10 -7 And M, the Raman enhancement effect is inferior to that of nano flower sphere-like or dumbbell-like nano spherical molybdenum dioxide.
Comparative example 2
A method for preparing a surface-enhanced raman spectroscopy substrate based on a metal oxide, comprising the following steps: weighing 0.1g of molybdenum acetylacetonate, grinding in a mortar for 10-20 minutes, adding 50mL of absolute ethyl alcohol after finishing grinding, stirring for 24-48 hours, setting the rotating speed at 500-600 r/min, transferring the dissolved precursor liquid into a 100mL polytetrafluoroethylene reaction kettle for hydrothermal reaction, wherein the temperature in the hydrothermal process is 180 ℃, and the hydrothermal time is 12-16 hours.
Weighing a certain amount of the MoO 2 MoO with deionized water to form the concentration of 1-5 mg/mL 2 Mother liquor. Taking 10-50 mu LMoO with a pipette 2 Dispersing the liquid drop on the substrate, and then drying in an oven at 60 ℃ to obtain MoO 2 A substrate.
Prepared MoO with a pipette 2 100 mu L of 10 is dripped on the substrate -7 The R6G dye molecules of M are then dried in an oven at 60 ℃. After the sample is dried, 532nm laser is selected for Raman detection, and the detection limit is lower than 10 -7 M。
FIG. 17a is MoO 2 FIG. 17b is a scanning electron microscope image of MoO 2 SERS detection effect of (a). When only absolute ethyl alcohol is used as a solvent, the appearance of the sample is greatly changed, the sample presents nanospheres, and the size is about 5-10 mu m. At this time, the detection effect of the substrate is greatly influenced by the morphology, and the detection limit is lower than 10 -7 M, the enhancement effect is inferior to that of nano flower sphere-like or dumbbell-shaped nano spherical molybdenum dioxide.
Comparative example 3
A method of "photo-erasable" removal of adsorbed molecules from a surface of a substrate, the method comprising the steps of: the concentration of R6G after detection is 10 -4 The molybdenum dioxide substrate of M is irradiated under 808nm laser with the laser power density of 0.5W/cm 2 The detection was performed every 10 minutes to observe the change in R6G signal. The probe molecule signal is still present after about 60 minutes of laser irradiation.
FIG. 18 shows a laser power density of 0.5W/cm 2 Under, the R6G raman signal changes during the photo-erasable process. After 60 minutes of irradiation, the raman signal of R6G was attenuated and did not completely disappear, indicating only partial decomposition of the dye molecules at the substrate surface. When the laser power density is 0.5W/cm as shown in FIG. 6a 2 When the surface temperature of the molybdenum dioxide substrate is lower than 200 ℃ (near the lowest temperature of decomposition of dye molecules, fig. 6 c-6 f), the dye molecules on the surface of the molybdenum dioxide substrate are only partially decomposed correspondingly.
Comparative example 4
A method for removing dye molecules by 'photo-erasable' method, wherein 10 mu L of 10 is dripped on a blank substrate by a liquid-transfering gun -4 M, then drying in an oven at 60deg.C, and collecting the dried dye molecules of R6G, rhB, MB or CV with concentration of 10 -4 The M substrate is irradiated under 808nm near infrared laser for 30 minutes, and the laser power density is 1.5W/cm 2 In Ar/N 2 And (3) irradiating in the atmosphere, wherein dye molecules are not decomposed after the irradiation is finished.
FIGS. 19a to 19d show the dropping of 10. Mu.L 10 on a blank substrate before and after irradiation -4 The R6G/RhB/MB/CV dye molecule schematic diagram of M has no obvious change before and after light irradiation, which shows that the dye molecule R6G/RhB/MB/CV is not decomposed on a blank substrate. This is because the blank base has no thermal effect under laser irradiation, the corresponding dye does not decompose, and only when molybdenum dioxide exists as a substrate, the temperature of the substrate surface rises under laser irradiation, and dye molecules decompose.
As can be seen from the experimental results of example 1, example 2, example 6, example 7, comparative example 1 and comparative example 2, it is only when the ratio of deionized water and ethanol is proper that nano flower-like sphere or dumbbell-like nano sphere MoO can be obtained 2 The ratio of deionized water to ethanol and the dosage of molybdenum acetylacetonate to MoO 2 The morphology of the molybdenum dioxide sample is changed to a certain extent, the proportion of deionized water and ethanol is changed within a certain range, the dosage of the molybdenum acetylacetonate has little influence on the detection and the photo-wiping performance of the molybdenum dioxide substrate, but when only deionized water or absolute ethanol is used as a solvent, the morphology of the prepared molybdenum dioxide sample is changed to a large extent, the Raman enhancement effect of the prepared substrate is poor, and the detection sensitivity is lower than 10 -7 M。
As can be seen from the experimental results of example 2, example 3, example 4, example 5 and comparative example 4, moO 2 Minimum detection limit for four probe moleculesIs 10 -7 M, on the blank substrate, the detection limit of the probe molecules is lower than 10 -7 M。MoO 2 At N 2 The thermogravimetric curve in (2) shows MoO in the temperature range of 300-700 DEG C 2 MoO at different laser power densities without decomposition 2 Can realize the temperature change of 200-400 ℃ and MoO 2 Has excellent chemical, thermal and radiation stability, and can still maintain the structural stability after 5-cycle test. Four dye molecules R6G, rhB, MB, CV begin to decompose at around 200 ℃. Placing the detected substrate under 808nm near infrared laser with laser power density of 1.5W/cm 2 In Ar/N 2 When the probe molecule signal disappears within 10 minutes after irradiation in the atmosphere, the molecules adsorbed on the surface are removed, and the substrate can be reused. On the blank substrate, the probe molecules are still present after laser irradiation.
As is evident from the experimental results of example 3, example 4, example 8, example 9, example 10 and comparative example 3, the laser power density has a large influence on the degradation time, as the laser power density is from 0.75W/cm 2 Changing to 2W/cm 2 The time required for degradation is gradually shortened, but when the laser power density is lower than 0.75W/cm 2 When the surface temperature of the molybdenum dioxide substrate is lower than the lowest temperature of dye molecule decomposition, the dye molecule decomposition on the surface of the substrate is not thorough.
Claims (10)
1. The preparation method of the reusable Raman enhanced substrate is characterized by comprising the following steps of:
s1: nanometer MoO 2 Is prepared from
Dissolving molybdenum acetylacetonate in ethanol water solution to form a precursor solution; carrying out hydrothermal reaction on the precursor solution, centrifuging to collect precipitate after the reaction, and then washing and drying to obtain the nano MoO 2 ；
S2: preparation of reusable raman-enhanced substrates
Nanometer MoO prepared in the step S1 2 MoO of 1-5 mg/mL 2 Aqueous dispersion of MoO 2 The aqueous dispersion is dropped on a substrate and dried to prepare MoO 2 The substrate is the reusable Raman enhanced substrate.
2. The method of claim 1, wherein the ethanol content of the aqueous ethanol solution in step S1 is 18% to 80% (v/v).
3. The method for preparing a reusable raman reinforced substrate according to claim 1, wherein the hydrothermal reaction in step S1 is performed at a temperature of 180 to 200 ℃ for a reaction time of 12 to 16 hours.
4. The method for preparing a reusable raman reinforced substrate according to claim 1, wherein in step S1, molybdenum acetylacetonate is dissolved in an aqueous ethanol solution in a stirring state to form a precursor solution, wherein the stirring speed is 500-600 r/min, and the stirring time is 24-48 h.
5. A method of preparing a reusable raman-enhanced substrate according to claim 1, wherein said washing in step S1 comprises the steps of: and centrifugally cleaning the centrifugally collected precipitate for 5-10 min at 8000-15000r/min by using absolute ethyl alcohol, and then centrifugally cleaning the precipitate for 10-15 min at 8000-15000r/min by using water for at least 3 times.
6. The method of making a reusable raman reinforced substrate according to claim 1 wherein said substrate is a cover slip or a silicon wafer.
7. A reusable raman-enhanced substrate, characterized in that it is a MoO produced by the production process according to any one of claims 1 to 6 2 A substrate.
8. A method of cleaning and recycling a raman-enhanced substrate according to claim 7, comprising the steps of:
and (3) carrying out near infrared laser irradiation or xenon lamp irradiation on the Raman enhanced substrate until the surface temperature reaches 200-400 ℃, and decomposing and removing the compound on the surface of the Raman enhanced substrate to achieve the aim of cleaning and recycling the surface of the Raman enhanced substrate.
9. The method for cleaning and recycling a raman enhanced substrate according to claim 8 wherein said near infrared laser has a wavelength of 808nm and a laser power density of 0.75 to 2W/cm 2 The irradiation time is 5-20 min.
10. The method for cleaning and recycling a raman enhanced substrate according to claim 8 wherein the raman enhanced substrate is placed in Ar/N 2 Near infrared laser irradiation or xenon lamp irradiation is performed in atmosphere or air.
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| CN117420278B (en) * | 2023-12-18 | 2024-03-26 | 四川华景智农农业开发有限责任公司 | Food drying matter moisture detection system and detection method thereof |
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