CN112481608B

CN112481608B - Titanium substrate with metal nanoparticles growing on surface in situ and application thereof

Info

Publication number: CN112481608B
Application number: CN202011210614.4A
Authority: CN
Inventors: 宋启军; 孙国巍; 王婵; 付程; 方御
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2020-11-03
Filing date: 2020-11-03
Publication date: 2021-09-24
Anticipated expiration: 2040-11-03
Also published as: CN112481608A

Abstract

The invention discloses a titanium substrate with metal nanoparticles growing on the surface in situ and application thereof, belonging to the field of enhanced Raman substrate preparation technology and detection. The method comprises the steps of immersing a pretreated titanium substrate into chemical deposition liquid, depositing for 30 s-2 h at 0-60 ℃, taking out, cleaning and drying to obtain the titanium substrate with the metal nanoparticles growing on the surface in situ, wherein the chemical deposition liquid comprises 5-40 g/L of ammonium fluoride, 1-50 g/L of metal salt, 5-30 g/L of citric acid and 0.1-1 vol% of strong acid. According to the invention, the etching rate of particles on the surface of the titanium substrate and the diffusion speed of trivalent titanium ions are regulated, so that the reduction reaction of metal particles occurs in a solution near the surface of the substrate, and thus, metal elements are loaded on the surface of the titanium substrate in the form of nanoparticles. The method realizes the uniform and compact growth of the nano particle layer without dead angles on the titanium-based surface, and greatly improves the surface enhanced Raman effect.

Description

Titanium substrate with metal nanoparticles growing on surface in situ and application thereof

Technical Field

The invention relates to a titanium substrate with metal nanoparticles growing on the surface in situ and application thereof, belonging to the field of enhanced Raman substrate preparation technology and detection.

Background

Since the discovery of surface enhanced raman scattering in 1974, raman detection has become the most attractive analytical tool in the field of ultrasensitive detection. Surface enhanced raman techniques are also considered to be one of the most promising research directions in the detection of small molecules. By using the surface enhanced Raman imaging technology, multi-target analysis and biological image signals with higher spatial resolution can be obtained, and the visualization of distribution areas of different doping materials can be realized. Label-free detection can also be achieved when analyzing various biological samples. With the introduction of electromagnetic field theory into the research of surface enhanced Raman substrates, two factors, namely electromagnetic effect and chemical effect, are found to be the most important enhancement mechanisms of Raman enhancement. Some researchers believe that raman signals can be enhanced by at least 8-10 times and chemical enhancement factors can be increased by 1-2 orders of magnitude by electromagnetic field surface resonance excitation.

Researchers combine a finite time difference method to estimate the distribution and enhancement of an electromagnetic field, and find that not only three metals (gold, silver and copper) can excite strong surface plasmon resonance to realize larger Raman signal enhancement, but also some other materials can be used for enhancing Raman, such as platinum, zinc oxide/ferroferric oxide compound and cobalt/tin oxide compound. Silver has led a great deal of research by researchers because of its high plasma activity, proper dielectric function and low cost.

Many recent enhanced raman studies have been associated with the use of silver nanoparticles. The prepared silver nanoparticles are mostly loaded on the base material in a substrate preparation mode, so that the prepared enhanced Raman substrate is quite uneven, and the surface metal nanoparticles are easy to fall off, so that the detected Raman signal is directly influenced. Therefore, it is necessary to find an enhanced raman substrate with stable and uniform signal and less peeling off.

Disclosure of Invention

Aiming at the problems that the surface of the enhanced Raman substrate prepared by the traditional method has uneven distribution of metal nano particles with different degrees, the nano particles are easy to fall off, the preparation process is complicated, the enhanced Raman substrate cannot be used in large batch and the like, the invention provides a method for directly obtaining the metal nano particles/titanium surface enhanced Raman substrate by adopting in-situ chemical deposition in a solution phase through one-pot reduction reaction, and four major disadvantages existing in the traditional method are improved.

The first object of the invention is to provide a method for preparing a titanium substrate with metal nano particles growing on the surface in situ, which comprises the following steps: immersing the pretreated titanium substrate into chemical deposition liquid for deposition for a period of time, taking out, cleaning and drying to prepare the titanium substrate with the metal nanoparticles growing on the surface in situ, wherein the chemical deposition liquid comprises 5-40 g/L of ammonium fluoride, 1-50 g/L of metal salt, 5-30 g/L of citric acid and 0.1-1 vol% of strong acid.

In one embodiment of the present invention, the time for the chemical deposition is 30s to 2 h.

In one embodiment of the present invention, the temperature of the chemical deposition is 0 to 60 ℃, and preferably 35 to 50 ℃.

In one embodiment of the present invention, the metal salt comprises one or more of gold, silver, nitrate, chloride, and sulfate of copper.

In one embodiment of the invention, the strong acid comprises any one or more of hydrochloric acid, sulfuric acid or nitric acid.

In one embodiment of the present invention, the pretreated titanium substrate is specifically pretreated by: degreasing a titanium plate in an alkaline solution; after being taken out and cleaned, the substrate is immersed in oxalic acid solution for etching.

In one embodiment of the present invention, the etching is performed at 60 to 100 ℃ for 3 to 8 hours.

In one embodiment of the present invention, the concentration of oxalic acid is 10 to 25 wt%.

In one embodiment of the invention, the alkaline solution comprises one or both of a sodium hydroxide solution or a sodium carbonate solution.

In one embodiment of the invention, the sodium hydroxide solution is preferably at a concentration of 1 wt% to 10 wt%, and the sodium carbonate solution is preferably at a concentration of 1 wt% to 30 wt%.

In one embodiment of the invention, the oil removing process can be performed under ultrasound, and the ultrasound treatment is performed for 20-100 min.

In one embodiment of the invention, the mass-to-volume ratio of the titanium substrate to the chemical deposition solution is 0-0.05 g/mL, and preferably 0.03 g/L.

The second purpose of the invention is to improve the titanium substrate with the metal nano particles growing on the surface in situ prepared by the method.

The third purpose of the invention is the application of the titanium substrate with the metal nano particles growing on the surface in situ in the fields of enhanced Raman substrates and substance detection.

The fourth purpose of the invention is to provide a method for detecting substances by utilizing Raman spectrum, which utilizes the titanium substrate with the metal nano particles grown in situ on the surface for detection.

In one embodiment of the present invention, the substance is any substance capable of generating a raman spectrum, including organic and inorganic substances.

In one embodiment of the present invention, preferably, the substance includes any one of p-aminophenol, p-mercaptobenzoic acid, rhodamine 6G, uric acid, or picric acid.

Has the advantages that:

(1) the method realizes a tighter dead-angle-free nano particle layer on the surface of the titanium substrate through chemical deposition, enables the reduction reaction of metal particles to occur in a solution near the surface of the substrate through regulating and controlling the etching rate of particles on the surface of the substrate and the diffusion rate of trivalent titanium ions, enables the metal nanoparticles to gather and grow at etching points on the surface of the titanium in the solution, realizes that metal elements are loaded on the surface of the titanium substrate in the form of the nanoparticles, greatly improves the surface enhanced Raman effect, and obtains the enhanced Raman substrate with more stable signals and more excellent Raman enhancement effect.

(2) The titanium substrate with the metal nano particles grown in situ on the surface prepared by the invention has very high Raman detection limit, and the detection limit of rhodamine 6G reaches 1 multiplied by 10^-10The detection limit of M and picric acid also reaches 1 × 10^-14More than M, the detection limit of uric acid molecules also reaches 1 multiplied by 10^-6M, the preparation of the substrate is simple and rapid, the combination of the nano particles and the substrate is firm, the chemical stability is good, and the prepared nano particles are expected to be applied to the high-resolution detection of gas-phase molecules.

Drawings

Fig. 1 is a cold field Scanning Electron Microscope (SEM) photograph of the copper nanosphere-loaded titanium-based enhanced raman substrate of example 1.

FIG. 2 is a graph showing the measurement of 1X 10 for the enhanced Raman substrate prepared in examples 1 to 3^-5M rhodamine 6G solutionRaman spectra of the liquid (after baseline correction) where Cu, Au and Ag represent the copper nanosphere-loaded titanium-based enhanced raman substrate of example 1, the gold nanoflower-loaded titanium-based enhanced raman substrate of example 2 and the silver nanosphere-loaded titanium-based enhanced raman substrate of example 3, respectively.

Fig. 3 is a cold field Scanning Electron Microscope (SEM) photograph of the gold nanoflowers-loaded titanium-based enhanced raman substrate of example 2.

Fig. 4 is a cold field Scanning Electron Microscope (SEM) photograph of the silver nanosphere-loaded titanium-based enhanced raman substrate of example 3.

Fig. 5 shows the raman spectrum signal response (after baseline correction) of the silver nanosphere-loaded titanium-based enhanced raman substrate prepared in example 3 to different concentrations of R6G.

Fig. 6 shows the response of the raman spectrum signals of the substrate (after baseline correction) of 15 different test points in example 3.

Fig. 7 is a comparison of raman spectrum signals of the silver nanosphere loaded titanium-based enhanced raman substrate obtained in example 4 at different deposition times (30s, 3min, 10min) at 0 ℃ with rhodamine 6G (R6G) as a target molecule.

FIG. 8 is a comparison of Raman spectrum signals of the titanium-based enhanced Raman substrate loaded with silver nanospheres obtained in example 5 at different deposition times (30s, 3min and 10min) at 20 ℃ and rhodamine 6G (R6G) as a target molecule.

Fig. 9 is a comparison of raman spectrum signals of the silver nanosphere loaded titanium-based enhanced raman substrate obtained in example 6 at different deposition times (30s, 3min, 10min) at 50 ℃ with rhodamine 6G (R6G) as a target molecule.

Fig. 10 is a cold field Scanning Electron Microscope (SEM) photograph of the silver nanosphere-enhanced raman substrate obtained in example 6 by deposition at 50 ℃ for 10 min.

FIG. 11 is an assay of 1X 10 copper nanosphere-loaded titanium-based enhanced Raman substrate of example 11^-5Raman spectrum of M rhodamine 6G solution.

FIG. 12 is a graph of the measurement of 1X 10 on the titanium-based enhanced Raman substrate loaded with silver nanospheres prepared in example 6^-8M p-aminophenolRaman spectrum of the solution.

FIG. 13 is a graph of the measurement of 1X 10 on the titanium-based enhanced Raman substrate loaded with silver nanospheres prepared in example 6^-8Raman spectrum of M p-mercaptobenzoic acid solution.

FIG. 14 is a graph of the measurement of 1X 10 on the titanium-based enhanced Raman substrate loaded with silver nanospheres prepared in example 6^-6Raman spectra of M uric acid solutions (after baseline correction).

FIG. 15 is a graph of 1X 10 measured on a titanium-based enhanced Raman substrate loaded with silver nanospheres prepared in example 6^-14Raman spectra of M picric acid solutions (after baseline correction).

Detailed Description

The present invention is further described below with reference to examples, but the embodiments of the present invention are not limited thereto.

The test method comprises the following steps:

cold field scanning electron microscope: s-4800, Japan;

laser confocal raman spectroscopy: InVia;

theoretical calculation simulation of the picric acid solution in example 4 was performed using Gaussion03 software.

Example 1

Alkaline degreasing: preparing NaOH (4 wt%) and Na₂CO₃(2 wt%) of the solution A batch of 1cm by 3cm by 0.5cm titanium substrates was immersed in the solution and sonicated at 53kHz and 250W for 30 min.

Etching by oxalic acid: and washing the degreased titanium plate with clear water, soaking the degreased titanium plate into a 20 wt% oxalic acid solution, controlling the temperature of the solution to be 98 ℃, etching for 5 hours, taking out the titanium plate, and cleaning the titanium plate for later use.

Chemically growing the copper nanospheres: immersing the pretreated titanium plate in prepared chemical deposition liquid, wherein the prepared chemical deposition liquid comprises ammonium fluoride (8g/L), copper sulfate pentahydrate (20g/L), citric acid (20g/L) and sulfuric acid (0.8 vol%), depositing for 3 minutes at 20 ℃, taking out, cleaning and drying by nitrogen, thus preparing the copper nanosphere-loaded titanium-based enhanced Raman substrate.

Fig. 1 is a cold field scanning electron microscope photograph of the prepared copper nanosphere-loaded titanium-based enhanced raman substrate, and it can be seen that the copper nanospheres are formed and uniformly distributed.

The testing process comprises the following steps: rhodamine 6G was arranged at 1X 10^-5After the M solution is placed uniformly, taking a small amount of culture dish, putting the prepared copper nanosphere-loaded titanium-based enhanced Raman substrate into the culture dish, standing for 30 minutes, taking out and drying, and performing Raman scattering spectrum presentation under the laser with the wavelength of 785nm, wherein the result is shown in figure 2. As can be seen, when the copper nanosphere-loaded titanium-based enhanced Raman substrate is taken as the substrate, the Raman scattering light intensity of rhodamine 6G is stronger, namely the substrate can be used for measuring 1 x 10^-5M in rhodamine 6G solution.

Example 2

Alkaline degreasing: a100 mL solution of NaOH (10 wt%) solution was prepared, and a batch of 1 cm. times.1 cm. times.0.5 cm titanium substrates was immersed in the solution and sonicated at 53kHz and 250W for 1 hour.

Etching by oxalic acid: and (3) washing the degreased titanium plate with clear water, soaking the degreased titanium plate into an oxalic acid (15 wt%) solution, controlling the temperature of the solution to be 98 ℃, etching for 3 hours, taking out the titanium plate, and cleaning the titanium plate for later use.

Chemically growing gold nanoflowers: immersing the pretreated titanium plate in prepared chemical deposition solution, wherein the solution comprises ammonium fluoride (10g/L), chloroauric acid (1g/L), citric acid (20g/L) and hydrochloric acid (0.4 vol%), depositing for 2 minutes at 20 ℃, taking out, cleaning, and drying by nitrogen, thus obtaining the titanium-based enhanced Raman substrate loaded with gold nanoflowers.

Fig. 3 is a cold field scanning electron microscope photograph of the prepared gold nanoflower-loaded titanium-based enhanced raman substrate, and it can be seen that gold nanoflowers are formed and uniformly distributed.

The testing process comprises the following steps: rhodamine 6G was arranged at 1X 10^-5And (3) after the M solution is placed uniformly, taking a small amount of culture dish, putting the prepared gold nanoflower-loaded titanium-based enhanced Raman substrate into the culture dish, standing for 30 minutes, taking out and drying. The raman scattering spectrum was obtained with a laser having a wavelength of 785nm, and the result is shown in fig. 2.

Example 3

Alkaline degreasing: configuration of Na₂CO₃(5 wt%) of the solution 100mL, a batch of 3cm by 0.5cm titanium substrates was immersed in the solutionAnd (5) carrying out ultrasonic treatment for 60 min.

Etching by oxalic acid: and (3) washing the degreased titanium plate with clear water, soaking the degreased titanium plate into an oxalic acid (10 wt%) solution, controlling the temperature of the solution to be 98 ℃, etching for 8 hours, taking out the titanium plate, and cleaning the titanium plate for later use.

Chemically growing silver nanospheres: immersing the pretreated titanium plate in prepared chemical deposition liquid, wherein the prepared chemical deposition liquid comprises ammonium fluoride (8g/L), silver nitrate (10g/L), citric acid (20g/L) and sulfuric acid (0.4 vol%), depositing for 3 minutes at 20 ℃, taking out, cleaning, and drying by nitrogen, thus obtaining the silver nanosphere loaded titanium-based enhanced Raman substrate.

Fig. 4 is a cold field scanning electron microscope photograph of the prepared silver nanosphere-loaded titanium-based enhanced raman substrate, and it can be seen that silver nanospheres are formed, and are uniformly distributed without agglomeration.

The testing process comprises the following steps: will be 1 × 10^-6After the M rhodamine 6G (R6G) solution is prepared and placed evenly, taking a small amount of culture dish, putting the prepared silver nanosphere loaded titanium-based enhanced Raman substrate into the culture dish, standing for 30 minutes, taking out and drying. The Raman scattering spectrum was obtained with a laser having a wavelength of 532nm, and the result is shown in FIG. 2. Therefore, compared with the Raman enhancement substrate prepared in the embodiment 1-2, the Raman scattering intensity of the silver nanosphere-loaded titanium-based enhancement Raman substrate is higher than that of the silver nanosphere-loaded titanium-based enhancement Raman substrate.

The results of changing the concentration of R6G and determining its Raman scattering spectrum according to the above-described test procedure are shown in FIG. 5, which shows that the intensity of the signal peak of R6G molecule is regularly reduced with the decrease of the concentration, and the lowest concentration of 1X 10 can be detected^-10Raman intensity of R6G for M.

The detection concentration is 1 × 10^-6The substrate signal response conditions of 15 different test points of the Raman substrate in the M rhodamine 6G solution are shown in the figure 6, and the results show that the corresponding intensity changes of Raman scattering of the different test points are not large, which shows that the silver nanospheres are uniformly distributed on the titanium substrate, and the Raman signals have good reproducibility and uniform distribution effect.

Example 4

Alkaline degreasing: configuration of Na₂CO₃(5 wt%) 100mL of the solutionAnd (3) immersing a batch of 3cm multiplied by 0.5cm titanium substrates into the solution, and carrying out ultrasonic treatment for 60 min.

Chemically growing silver nanospheres: and immersing the pretreated titanium plate in prepared chemical deposition liquid, wherein the prepared chemical deposition liquid comprises ammonium fluoride (8g/L), silver nitrate (10g/L), citric acid (20g/L) and sulfuric acid (0.4 vol%), the titanium plate is deposited for 30 seconds, 3 minutes and 10 minutes respectively at 0 ℃, and the titanium plate is taken out and cleaned, and is dried by nitrogen, so that the titanium-based enhanced Raman substrate loaded with the silver nanospheres is prepared.

The testing process comprises the following steps: will be 1 × 10^-6And after the MR6G solution is prepared and placed uniformly, taking a small amount of culture dish, putting the prepared silver nanosphere-loaded titanium-based enhanced Raman substrate into the culture dish, standing for 30 minutes, taking out and drying. The raman scattering spectrum was obtained with a laser having a wavelength of 785nm and the results are shown in fig. 7, which shows that the raman signal gradually appears in the measurement process with the increase of the deposition time, but a hetero-peak (fluorescence-like peak) appears.

Example 5

Alkaline degreasing: configuration of Na₂CO₃(5 wt%) of the solution 100mL, a batch of 3cm by 0.5cm titanium substrates was immersed in the solution and sonicated for 60 min.

Chemically growing silver nanospheres: and immersing the pretreated titanium plate in prepared chemical deposition liquid, wherein the prepared chemical deposition liquid comprises ammonium fluoride (8g/L), silver nitrate (10g/L), citric acid (20g/L) and sulfuric acid (0.4 vol%), depositing for 30 seconds, 3 minutes and 10 minutes respectively at 20 ℃, taking out, cleaning, and drying with nitrogen to obtain the silver nanosphere loaded titanium-based enhanced Raman substrate.

The testing process comprises the following steps: will be 1 × 10^-6After the MR6G solution is prepared and placed evenly, a small amount of culture dish is taken, and the prepared silver nanosphere-loaded titanium-based enhanced Raman substrate is placed in a culture dish for cultureThe mixture was placed in a dish and left to stand for 30 minutes, and then taken out and left to dry. The raman scattering spectrum was developed with a laser at 785nm and the results are shown in fig. 8, indicating increased deposition time and enhanced raman signal, but unsatisfactory signal discrimination.

Example 6

Chemically growing silver nanospheres: and immersing the pretreated titanium plate in prepared chemical deposition liquid, wherein the prepared chemical deposition liquid comprises ammonium fluoride (8g/L), silver nitrate (10g/L), citric acid (20g/L) and sulfuric acid (0.4 vol%), depositing for 30 seconds, 3 minutes and 10 minutes respectively at 50 ℃, taking out, cleaning, and drying with nitrogen to obtain the silver nanosphere loaded titanium-based enhanced Raman substrate.

The testing process comprises the following steps: will be 1 × 10^-6And after the MR6G solution is prepared and placed uniformly, taking a small amount of culture dish, putting the prepared silver nanosphere-loaded titanium-based enhanced Raman substrate into the culture dish, standing for 30 minutes, taking out and drying. The raman scattering spectrum was developed with a laser at 785nm and the results are shown in fig. 9, indicating increased deposition time and enhanced raman signal. The microscopic morphology of the surface of the titanium substrate obtained after 10 minutes of deposition is shown in figure 10, and silver is uniformly distributed on the titanium substrate in a nanometer spherical shape.

Example 7

Etching by oxalic acid: washing the degreased titanium plate with clean water, soaking the degreased titanium plate into an oxalic acid (10 wt%) solution, controlling the temperature of the solution to 98 ℃, etching for 8 hours, taking out the titanium plate, and cleaning the titanium plate for later use.

Chemically growing gold and silver nanospheres: immersing the pretreated titanium plate in prepared chemical deposition liquid, wherein the prepared chemical deposition liquid comprises ammonium fluoride (8g/L), silver nitrate (10g/L), chloroauric acid (1g/L), citric acid (20g/L) and sulfuric acid (0.4 vol%), depositing for 3 minutes at 20 ℃, taking out, cleaning, and drying with nitrogen to obtain the gold and silver nanosphere loaded titanium-based enhanced Raman substrate.

The testing process comprises the following steps: will be 1 × 10^-6After the MR6G solution is prepared and placed uniformly, a small amount of culture dish is taken, the prepared gold-silver nanosphere loaded titanium-based enhanced Raman substrate is placed in the culture dish, and the culture dish is kept stand for 30 minutes and then taken out and dried. The raman enhancement signal of R6G can also be obtained by performing raman scattering spectrum presentation with a laser having a wavelength of 785 nm.

Example 8

Soaking the titanium plate in a sodium hydroxide solution with the mass concentration of 5% for 2h, taking out and washing the titanium plate, putting the titanium plate into an oxalic acid solution with the mass concentration of 20%, reacting for 5h at 98 ℃, taking out and washing the titanium plate for later use.

Immersing the pretreated titanium plate in the prepared chemical deposition solution, wherein the solution comprises ammonium fluoride (40g/L), copper nitrate (50g/L), citric acid (30g/L) and nitric acid (0.1 vol%), depositing for 30s at 60 ℃, taking out and cleaning, and drying with nitrogen for later use, namely preparing the copper nanosphere-loaded titanium-based enhanced Raman substrate, and the SEM and the determination of R6G in the same embodiment 1 show that the copper nanospheres are uniformly distributed on the titanium substrate and can realize Raman spectrum enhancement.

Example 9

Soaking the titanium plate in a mixed solution of sodium hydroxide with the mass concentration of 4% and sodium carbonate with the mass concentration of 2% for 4 hours, taking out and washing the titanium plate, putting the titanium plate into an oxalic acid solution with the mass concentration of 25%, reacting the titanium plate for 5 hours at 98 ℃, taking out and washing the titanium plate for later use.

Immersing the pretreated titanium plate in the prepared chemical deposition solution, wherein the prepared chemical deposition solution comprises ammonium fluoride (30g/L), silver nitrate (20g/L), citric acid (1g/L) and hydrochloric acid (1 vol%), depositing for 2h at 0 ℃, taking out and cleaning, and drying with nitrogen for later use, namely preparing the silver nanosphere-loaded titanium-based enhanced Raman substrate, and the determination of SEM and R6G in the same embodiment 1 shows that the silver nanospheres are uniformly distributed on the titanium substrate and can realize Raman spectrum enhancement.

Example 10

Ultrasonically soaking a titanium plate in a mixed solution of sodium hydroxide with the mass concentration of 4% and sodium carbonate with the mass concentration of 4% for 30min, taking out and washing the titanium plate, putting the titanium plate into an oxalic acid solution with the mass concentration of 15%, reacting for 4h at 98 ℃, taking out and washing the titanium plate for later use.

Immersing the pretreated titanium plate in a prepared chemical deposition solution, wherein the prepared chemical deposition solution comprises ammonium fluoride (40g/L), chloroauric acid (1g/L), citric acid (20g/L) and sulfuric acid (0.1 vol%), depositing at 0 ℃ for 30s, taking out, cleaning and drying with nitrogen for later use, namely preparing the titanium-based enhanced Raman substrate loaded with the gold nanoparticles, and the gold nanoparticles are uniformly distributed on the titanium substrate and can realize Raman enhancement through SEM and determination of R6G in the same embodiment 1.

Example 11

The alkaline degreasing and oxalic acid etching steps are the same as example 2;

immersing the pretreated titanium plate in prepared chemical deposition liquid, wherein the prepared chemical deposition liquid comprises ammonium fluoride (20g/L), anhydrous copper sulfate (20g/L), citric acid (30g/L) and sulfuric acid (0.3 vol%), depositing for 2 hours at 0 ℃, taking out and cleaning, and drying with nitrogen for later use, thereby preparing the copper nanosphere-loaded titanium-based enhanced Raman substrate. According to the determination method of the example 1, the copper nanospheres are uniformly distributed on the titanium substrate, and the Raman enhancement can be realized, and the Raman intensity signals are shown in figure 11.

A large number of experiments show that when the chemical deposition solution comprises 5-40 g/L of ammonium fluoride, 1-50 g/L of metal salt, 5-30 g/L of citric acid and 0.1-1 vol% of strong acid, deposition is carried out for 30 s-2 h at 0-60 ℃, the etching rate of particles on the surface of the substrate and the diffusion rate of trivalent titanium ions can be regulated and controlled, so that the reduction reaction of the metal particles occurs in a solution near the surface of the substrate, and finally, the metal nanoparticles are gathered and grown at the etching points on the surface of the titanium in the solution, so that the metal elements are loaded on the surface of the titanium substrate in the form of nanoparticles.

Example 12

The raman substrate prepared with a deposition time of 10 minutes in example 6 was used for the test. Putting the Raman substrates into the container respectively with the configured 1 × 10 Raman substrates^-8M p-aminophenol solution, 1X 10^-8M p-mercaptobenzoic acid solutionLiquid, 1X 10^-6Uric acid of M and solution 1X 10^-14And standing the M picric acid solution for 30 minutes, taking out, drying, and performing Raman signal test, wherein the measurement result is shown in the figure 12-15. It can be seen that all have good raman signals, i.e. such substances can be detected through the substrate.

A large number of experiments show that the titanium substrate prepared by the method can detect various substances, including any substance capable of generating Raman scattering spectra.

Comparative example 1

When the chemical deposition solution is free of ammonium fluoride, other operation parameters are consistent with those of example 3, and as a result, the chemical deposition cannot be realized, and a titanium substrate loaded with metal nanoparticles cannot be obtained.

When no citric acid was present in the chemical deposition solution, the other operating parameters were consistent with those of example 3, and it was found that the deposited silver particles were not uniformly distributed and non-nanosphere in shape. Tests show that 1X 10 different points are taken on the substrate^-6When the MR6G molecule is used for Raman detection, only a few sites can present a high Raman signal effect, and most test points cannot present the Raman spectrum of the molecule.

Comparative example 2

When the concentration of ammonium fluoride in the chemical deposition solution is more than 40g/L and other operation parameters are consistent with those of example 3, the result shows that the etching reaction is too fast, so that metal particles are deposited on the surface of the substrate too fast, the deposition effect is not firm enough, the metal nanoparticles are not compact enough in distribution, and the metal nanoparticles can fall off by simple washing. The stability is extremely poor. The method regulates and controls the etching rate of particles on the surface of the substrate and the diffusion speed of trivalent titanium ions (by controlling the concentration of each component in the chemical deposition solution, the deposition temperature and time and the like), so that the reduction reaction of metal particles occurs in the solution near the surface of the substrate, and the metal nanoparticles are gathered and grown at the etching points on the surface of the titanium in the solution, thereby realizing that metal elements are loaded on the surface of the titanium substrate in the form of nanoparticles (such as nanospheres and nanoflowers), greatly improving the surface enhanced Raman effect, and obtaining the enhanced Raman substrate with more stable signals and more excellent Raman enhancement effect. The nano particles are connected with the titanium substrate more firmly and can not be washed away by simple washing.

When the concentration of the strong acid is greater than 1 vol%, other operation parameters are consistent with those of example 3, excessive strong acid can cause chemical etching to be a dominant reaction, chemical deposition cannot be realized, metal particles are all reduced in the solution, the solution color becomes turbid, suspension gradually gathers and deposits, and a substrate capable of effectively realizing raman scattering enhancement cannot be prepared.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for preparing a titanium substrate with metal nanoparticles grown in situ on the surface, the method comprising the steps of: immersing the pretreated titanium substrate into chemical deposition liquid for deposition for a period of time, taking out the titanium substrate, cleaning and drying the titanium substrate to obtain the titanium substrate with the metal nanoparticles growing on the surface in situ, wherein the chemical deposition liquid comprises 5-40 g/L of ammonium fluoride, 1-50 g/L of metal salt, 5-30 g/L of citric acid and 0.1-1 vol% of strong acid, and the metal salt comprises one or more of nitrate, chloride and sulfate of gold, silver and copper.

2. The method according to claim 1, wherein the chemical deposition is carried out at a temperature of 0 to 60 ℃ for 30s to 2 h.

3. The method of claim 1 or 2, wherein the strong acid comprises any one or more of hydrochloric acid, sulfuric acid, or nitric acid.

4. The method according to claim 1 or 2, wherein the pre-treating of the pre-treated titanium substrate comprises: the titanium plate is degreased in alkaline solution, taken out and cleaned, and then immersed in oxalic acid solution for etching.

5. The method of claim 3, wherein the pre-treating of the pre-treated titanium substrate comprises: the titanium plate is degreased in alkaline solution, taken out and cleaned, and then immersed in oxalic acid solution for etching.

6. The method of claim 4, wherein the alkaline solution comprises one or both of a sodium hydroxide solution or a sodium carbonate solution.

7. The method of claim 5, wherein the alkaline solution comprises one or both of a sodium hydroxide solution or a sodium carbonate solution.

8. The method of claim 4, wherein the etching is performed at 60-100 ℃ for 3-8 h.

9. The method according to any one of claims 5 to 7, wherein the etching is carried out at 60 to 100 ℃ for 3 to 8 hours.