阅读说明：本技术 纳米银修饰的氧化钛纳米管阵列及其制备方法和用途 (Nano-silver modified titanium oxide nanotube array and preparation method and application thereof ) 是由 朱储红 翟海超 袁玉鹏 杜海威 徐更生 严满清 江道传 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种纳米银修饰的氧化钛纳米管阵列及其制备方法和用途。氧化钛纳米管生长在导电衬底上,为单层氧化钛纳米阵列,银纳米颗粒修饰在氧化钛纳米管表面。其中,氧化钛纳米管的长度为4-10μm,直径为0.5-1μm,银纳米颗粒的粒径为20-150nm,具有大量位于银纳米颗粒间宽度≤10nm的间隙或缝隙；材料制备方法为：先在氧气气氛中利用等离子体轰击导电玻璃,增加其表面的亲水性；然后在60-80℃水浴的条件下,在位于锌氨溶液中的导电玻璃表面生长氧化锌纳米棒；然后在氟钛酸溶液的作用下,将氧化锌纳米棒原位转化成顶端封闭的氧化钛纳米管；最后利用银镜反应,在氧化钛纳米管表面修饰银纳米颗粒,制得目的产物。该产品具有较高的表面增强拉曼散射(SERS)活性,极易于广泛地商业化应用于对染色剂罗丹明6G的快速痕量检测。(The invention discloses a nano-silver modified titanium oxide nanotube array and a preparation method and application thereof. The titanium oxide nano-tube grows on the conductive substrate and is a single-layer titanium oxide nano-array, and the silver nano-particles are modified on the surface of the titanium oxide nano-tube. Wherein, the length of the titanium oxide nano-tube is 4-10 μm, the diameter is 0.5-1 μm, the grain diameter of the silver nano-particles is 20-150nm, and a large number of gaps or gaps with the width less than or equal to 10nm are arranged among the silver nano-particles; the preparation method of the material comprises the following steps: firstly, bombarding conductive glass by using plasma in an oxygen atmosphere to increase the hydrophilicity of the surface of the conductive glass; then growing a zinc oxide nano rod on the surface of the conductive glass in the zinc ammonia solution under the condition of water bath at the temperature of 60-80 ℃; then under the action of fluotitanic acid solution, the zinc oxide nano-rod is converted into a titanium oxide nano-tube with a closed top end in situ; and finally, modifying the surface of the titanium oxide nanotube with silver nanoparticles by using a silver mirror reaction to obtain a target product. The product has higher Surface Enhanced Raman Scattering (SERS) activity, and is extremely easy to be widely and commercially applied to rapid trace detection of dye rhodamine 6G.)

1. The nano-silver modified titanium oxide nanotube array is characterized by consisting of a single-layer titanium oxide nanotube modified by a plurality of silver nanoparticles arranged on a conductive substrate, wherein the titanium oxide nanotube modified by the silver nanoparticles consists of a titanium oxide nanotube and silver nanoparticles uniformly attached to the surface of the titanium oxide nanotube, one end of the titanium oxide nanotube far away from the conductive substrate is closed, the height of the titanium oxide nanotube is 4-10 mu m, the thickness of the tube wall is 200-400nm, the outer diameter is 0.5-1 mu m, the included angle between the axis of the tube and the plane of the conductive substrate is 50-90 degrees, the particle size of the silver nanoparticles is 20-150nm, and the gap between adjacent silver nanoparticles is 0-10 nm.

2. The nano-silver modified titanium oxide nanotube array of claim 1, wherein the conductive substrate is an indium tin oxide glass substrate, or a silicon wafer, or a fluorine-doped tin dioxide conductive glass substrate.

3. A method for preparing the nano-silver modified titanium oxide nanotube array of claim 1 or 2, comprising the following steps:

s1, bombarding the conductive surface of the conductive substrate with plasma in an oxygen atmosphere;

s2, preparing Zn (NH)₃)₄(NO₃)₂Vertically placing the conductive substrate in the zinc ammonia solution, growing for 60-90min in water bath at 60-80 deg.C, taking out after reaction, and using deionized waterWashing with water for 1-3 times, air drying at room temperature, and making zinc oxide nanorod array on the surface of the conductive substrate;

s3, preparing a fluotitanic acid solution, vertically putting the conductive substrate with the zinc oxide nanorod array growing on the surface into the fluotitanic acid solution at room temperature, reacting for 60-90min, taking out after the reaction is finished, washing with deionized water for 1-3 times, drying at room temperature, and preparing a titanium oxide nanotube with a closed upper end on the conductive substrate;

s4, finally, vertically placing the conductive substrate with the titanium oxide nanotube array growing on the surface into a silver ammonia solution for 20-30min under the condition of water bath at 40-60 ℃, modifying silver nanoparticles on the surface of the titanium oxide nanotubes, taking out after the reaction is finished, washing the conductive substrate with deionized water for 1-3 times, airing at room temperature, and preparing the titanium oxide nanotube array modified by the nano silver on the conductive substrate.

4. The method as claimed in claim 3, wherein the time for the plasma to bombard the conductive surface of the conductive substrate in step S1 is 240-360S, and after the bombardment is finished, the conductive substrate is washed with deionized water for 1-3 times and dried in an oven at 40-60 ℃.

5. The method for preparing nano-silver modified titanium oxide nanotube array according to claim 3, wherein the method for preparing the zinc ammonia solution in step S2 is as follows: adding 0.008-0.012mol of zinc nitrate hexahydrate into 100ml of water, fully dissolving, and dropwise adding 10 wt% ammonia water to clarify.

6. The method for preparing nano-silver modified titanium oxide nanotube array according to claim 3, wherein the method for preparing the fluotitanic acid solution in step S3 is as follows: adding 0.007 to 0.008mol of fluotitanic acid ammonia and 0.015 to 0.025mol of boric acid into 100ml of water, and uniformly mixing to obtain the product.

7. The method for preparing nano-silver modified titanium oxide nanotube array according to claim 3, wherein the method for preparing silver ammonia solution in step S4 is as follows: adding 0.015-0.025mol of silver nitrate and 0.04-0.06mol of glucose into 100ml of water, and uniformly mixing to obtain the silver nitrate-glucose mixed solution.

8. Use of the nanosilver-modified titanium oxide nanotube array of claim 1 or 2 as an active substrate for surface-enhanced raman scattering.

9. The use of the silver nanoparticle-modified titanium oxide nanotube array with the closed top as defined in claim 8, wherein the nano-silver-modified titanium oxide nanotube array is used as an active substrate for surface enhanced raman scattering, and when the content of rhodamine 6G attached to the nano-silver-modified titanium oxide nanotube array is measured by using a laser raman spectrometer, the wavelength of excitation light of the laser raman spectrometer is 532nm, the power of the excitation light is 0.1-2mW, and the integration time is 1-30 s.

Technical Field

The invention relates to the technical field of nano materials, in particular to a nano silver modified titanium oxide nanotube array and a preparation method and application thereof.

Background

The Surface Enhanced Raman Scattering (SERS) spectrum detection technology can provide a spectrum with fingerprint information of molecular vibration, and has important potential application prospects in the fields of trace detection and the like. In order to obtain high detection sensitivity, researchers have attempted to prepare SERS substrates with three-dimensional structures. For example, in the journal of "Nano Research", volume 8, No. 3, page 957-966, the Research results of "preparation of nanotube arrays assembled with noble metal nanostructure units by zinc oxide nanocone array sacrificial template method and their use as three-dimensional SERS substrates" are reported (ZnO-nanoparticle array synthesized of non-metallic building-block assembled nanotube arrays as 3D SERS-substrates, Nano Research2015,8(3), 957-966). The research utilizes zinc oxide nanocones as sacrificial templates to prepare noble metal nanotube arrays by electrodeposition in acid electrolyte.

In order to recycle the SERS substrate, researchers have prepared a composite-structure SERS substrate of noble metal/oxide nanostructures; after the SERS detection is finished, the organic molecules adsorbed on the surface of the SERS substrate are degraded by utilizing the photocatalytic performance of the oxide semiconductor, so that the cyclic utilization of the SERS substrate is realized. For example, researchers modify silver nanoparticles on the surface of a zinc oxide nanorod to prepare a zinc oxide nanorod array modified by the silver nanoparticles, so that rapid trace detection of pesticides is realized. However, since the zinc oxide nanorods are easily dissolved in an acidic aqueous solution, this limits the range of applications of such silver nanoparticle-modified zinc oxide nanorod array SERS substrates. In addition, the silver nanoparticles in the structure are modified by an ion sputtering method, and a relatively expensive ion sputtering instrument is required. Therefore, researchers have conducted further experiments, and in an application patent (application publication No. CN 105177671A) entitled "a method for preparing silver nanoparticle/titanium dioxide nanotube array", a titanium dioxide nanotube array was obtained by an anodic oxidation method, and silver nanoparticles were modified on the inner wall of the tube by silver mirror reaction to prepare a silver nanoparticle-modified titanium dioxide nanotube array. However, the outer wall of the titanium oxide nanotube prepared by the method is close to the outer wall of the titanium oxide nanotube, the outer surface of the titanium oxide nanotube is not exposed, the specific surface area of the titanium oxide nanotube is reduced seriously, in addition, the aperture of the prepared titanium oxide nanotube is small due to the limitation of a preparation method (the anodic oxidation voltage is 40-60V), and in the process of modifying silver nanoparticles on the inner wall of the titanium oxide nanotube, if the particle size of the silver nanoparticles is small (mostly smaller than 5nm), the photocatalytic performance and the SERS performance are reduced; if the particle size of silver nanoparticles is increased, the silver nanoparticles are easily connected with each other at the pipe orifice to form large particles, so that the pipe orifice is blocked, a large amount of silver nanoparticles are difficult to modify in the pipe, and finally the silver nanoparticles are mainly modified in a two-dimensional plane where the pipe orifice is located, which also seriously affects the photocatalytic performance and the SERS performance. Therefore, the method is simple and convenient, has low cost, can prepare the alkali-resistant and acid-resistant recyclable three-dimensional SERS substrate, and has important significance.

Disclosure of Invention

The invention aims to overcome the defects of photocatalysis performance and SERS performance of a titanium dioxide nanotube array modified by silver nanoparticles in the prior art, and provides a titanium dioxide nanotube array modified by nano silver and a preparation method and application thereof.

The invention aims to overcome the defects in the prior art and provide a titanium oxide nanotube array modified by nano silver, the nano-silver modified titanium oxide nanotube array consists of a plurality of single-layer silver nanoparticle modified titanium oxide nanotubes which are distributed on a conductive substrate, the titanium oxide nano-tube modified by the silver nano-particles consists of a titanium oxide nano-tube and silver nano-particles uniformly attached to the surface of the titanium oxide nano-tube, the end of the titanium oxide nanotube far away from the conductive substrate is closed, the height of the titanium oxide nanotube is 4-10 μm, the thickness of the tube wall is 200-400nm, the outer diameter is 0.5-1 μm, the included angle between the axis of the tube and the plane of the conductive substrate is 50-90 degrees, the particle size of the silver nano-particles is 20-150nm, and the gap between adjacent silver nano-particles is 0-10 nm.

The titanium oxide nanotube array modified by nano silver is further improved:

preferably, the conductive substrate is an indium tin oxide glass substrate, or a silicon wafer, or a fluorine-doped tin dioxide conductive glass substrate.

In order to solve the technical problem of the invention, another technical scheme is that the preparation method of the nano-silver modified titanium oxide nanotube array comprises the following steps:

s1, bombarding the conductive surface of the conductive substrate with plasma in an oxygen atmosphere;

s2, preparing Zn (NH)₃)₄(NO₃)₂Vertically putting the conductive substrate into the zinc ammonia solution, growing for 60-90min under the condition of water bath at 60-80 ℃, taking out the conductive substrate after the reaction is finished, washing the conductive substrate for 1-3 times by using deionized water, drying the conductive substrate at room temperature, and preparing a zinc oxide nano rod on the surface of the conductive substrate;

s3, preparing a fluotitanic acid solution, vertically putting the conductive substrate with the zinc oxide nanorod array growing on the surface into the fluotitanic acid solution at room temperature, reacting for 60-90min, taking out after the reaction is finished, washing with deionized water for 1-3 times, drying at room temperature, and preparing a titanium oxide nanotube with a closed upper end on the conductive substrate;

s4, finally, vertically placing the conductive substrate with the titanium oxide nanotube array growing on the surface into a silver ammonia solution for 20-30min under the condition of water bath at 40-60 ℃, modifying silver nanoparticles on the surface of the titanium oxide nanotubes, taking out after the reaction is finished, washing the conductive substrate with deionized water for 1-3 times, airing at room temperature, and preparing the titanium oxide nanotube array modified by the nano silver on the conductive substrate.

The further technical proposal of the preparation method of the nano-silver modified titanium oxide nanotube array is as follows:

preferably, the time for the plasma to bombard the conductive surface of the conductive substrate in step S1 is 240-360S, and after the bombardment is finished, the conductive substrate is washed with deionized water for 1-3 times and dried in an oven at 40-60 ℃.

Preferably, the preparation method of the zinc ammonia solution in the step S2 is as follows: adding 0.008-0.012mol of zinc nitrate hexahydrate into 100ml of water, fully dissolving, and dropwise adding 10 wt% ammonia water to clarify.

Preferably, the method for preparing the fluotitanic acid solution in the step S3 is as follows: adding 0.007 to 0.008mol of fluotitanic acid ammonia and 0.015 to 0.025mol of boric acid into 100ml of water, and uniformly mixing to obtain the product.

Preferably, the preparation method of the silver ammonia solution in step S4 is as follows: adding 0.015-0.025mol of silver nitrate and 0.04-0.06mol of glucose into 100ml of water, and uniformly mixing to obtain the silver nitrate-glucose mixed solution.

In order to solve the technical problem of the invention, the invention adopts another technical scheme that the titanium oxide nanotube array modified by nano silver is used as an active substrate for surface enhanced Raman scattering.

The application of the nano-silver modified titanium oxide nanotube array as an active substrate for surface enhanced Raman scattering is further improved:

preferably, the nano-silver modified titanium oxide nanotube array is used as an active substrate for surface enhanced Raman scattering, and when the content of rhodamine 6G attached to the nano-silver modified titanium oxide nanotube array is measured by using a laser Raman spectrometer, the wavelength of exciting light of the laser Raman spectrometer is 532nm, the power of the exciting light is 0.1-2mW, and the integration time is 1-30 s.

Compared with the prior art, the invention has the beneficial effects that:

firstly, the top end closed titanium oxide nanotube array modified by the silver nanoparticles is positioned on the conductive substrate, the structure is uniform, the specific surface area of the product is large, SERS signals are uniform, and the detection sensitivity is high. In addition, the particle diameter of the silver nanoparticles modified on the surface of the titanium dioxide nanotube is proper, and the silver nanoparticles are uniformly distributed and densely modified. Because the zinc oxide nano rod can be dissolved in the acidic solution, the SERS substrate is damaged, the silver nano particle modified zinc oxide nano rod array in the prior art can only detect molecules in neutral and alkaline solutions, and the nano silver modified titanium oxide nano rod array can be applied to more environments, such as an acidic environment, a neutral environment and an alkaline environment. The top-closed titanium oxide nanotube array modified by the silver nanoparticles prepared by the method has photocatalytic performance and recycling performance, can detect molecules in acidic, neutral and alkaline solutions, and has a wider application range.

Secondly, the preparation method is simple and low in cost. The conductive surface of the conductive substrate is bombarded by plasma in an oxygen atmosphere, so that the hydrophilicity of the surface of the conductive substrate is increased, the uniform nucleation and growth of zinc oxide seed crystals on the surface of the conductive substrate are facilitated, and the precondition is provided for the zinc oxide nanorod array with the uniformly distributed growth area; the preparation method adopts silver mirror reaction to modify dense silver nanoparticles on the surface of the titanium oxide nanotube, thereby avoiding sputtering silver by using an ion sputtering instrument to achieve the purpose of modifying the nanoparticles. Therefore, the preparation method provided by the invention is more convenient to popularize and use.

Thirdly, compared with the method for modifying the silver nanoparticles by ion sputtering, the silver nanoparticles obtained by the method for modifying the silver nanoparticles by silver mirror reaction are more uniformly distributed. The reason is that: during ion sputtering, the silver source moves from a direction similar to a specific direction to the surface of the oxide nanorods or nanotubes, so that the quantity of silver nanoparticles modified at the bottom end or one side of the bottom end of the oxide nanorods is extremely small, and the SERS activity and the detection sensitivity of the SERS substrate are reduced. The silver nanoparticles are modified by silver mirror reaction, so that the problem that the modified silver nanoparticles are not uniform can be effectively avoided; the exposed surface of the oxide nanotubes is able to contact a silver source and grow silver nanoparticles.

Fourthly, the particle diameter of the silver nanoparticles obtained by the method for modifying the silver nanoparticles through silver mirror reaction is appropriate and adjustable in a larger size range, the silver nanoparticles are uniformly distributed on the surface of the titanium dioxide nanotube, and the silver nanoparticles are densely modified. In addition, the obtained titanium oxide nanotube array modified by the silver nanoparticles and closed at the top has large specific surface area and good photocatalytic degradation performance.

Drawings

FIG. 1 shows the results of characterization of the ZnO nanorods and Titania nanotubes obtained in example 5 by Scanning Electron Microscopy (SEM). In fig. 1, (a) is an SEM image of the zinc oxide nanorods, and (b) is an SEM image of the titanium oxide nanotubes.

FIG. 2 shows one of the results of characterization of the objective product obtained in example 5 using a Scanning Electron Microscope (SEM). In fig. 2, (a) is an SEM image of a target product, and (b) is a high-magnification SEM image of the target product.

FIG. 3 shows one of the results of the characterization of the target product with different concentrations of rhodamine 6G attached to the sample prepared in example 5 using a laser Raman spectrometer. Curve a in fig. 3 is a graph containing 1 × 10^–8The Raman spectrum line of the target product of mol/L rhodamine 6G, and the curve b is that the target product contains 1 multiplied by 10^–9The Raman spectrum line of the target product of mol/L rhodamine 6G, and the curve c is that the target product contains 1 multiplied by 10^{– 10}The Raman spectrum line of the target product of mol/L rhodamine 6G, and the curve d is that the target product contains 1 multiplied by 10^–11And the Raman spectrum line of the target product of mol/L rhodamine 6G.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to embodiments, and all other embodiments obtained by a person of ordinary skill in the art without any creative effort based on the embodiments of the present invention belong to the protection scope of the present invention.

First commercially available or manufactured on its own:

a silicon chip substrate used as a conductive substrate, an indium tin oxide glass substrate and a fluorine-doped tin dioxide conductive glass substrate;

ethanol; zinc nitrate pentahydrate; ammonia water; silver nitrate; glucose;

deionized water.

Example 1

A silicon wafer substrate is selected as a conductive substrate, and the preparation method comprises the following specific steps:

01. bombarding a conductive surface of a conductive substrate for 240s by utilizing plasma in an oxygen atmosphere, adding hydrophilicity on the surface, cleaning the surface of the conductive substrate for 1 time by using deionized water after the bombardment is finished, and drying in a 60 ℃ drying oven;

02. preparing a zinc oxide nanorod array: adding 100ml of water into 0.008mol of zinc nitrate hexahydrate, fully dissolving, dropwise adding 10 wt% ammonia water to clear, vertically placing the conductive substrate into a zinc-ammonia solution under the condition of 60 ℃ water bath, and growing a zinc oxide nanorod on the surface of the conductive substrate for 60 min. After the reaction is finished, the surface of the conductive substrate on which the zinc oxide nanorod array grows is washed by deionized water for 1 time, and then dried at room temperature.

03. Preparing a titanium oxide nanotube array: adding 100ml of water into 0.0070mol of ammonium fluorotitanate and 0.015mol of boric acid, fully dissolving, vertically placing the conductive substrate with the zinc oxide nanorod arrays growing on the surface into the fluorotitanate solution at room temperature, and carrying out chemical reaction for 60min to convert the zinc oxide nanorods into the titanium oxide nanotubes in situ. After the reaction is finished, the surface of the conductive substrate on which the titanium oxide nanotube array grows is cleaned by deionized water for 1 time, and then dried at room temperature.

04. Preparing a titanium oxide nanotube array modified by silver nanoparticles with a closed top end: adding 100ml of water into 0.015mol of silver nitrate and 0.040mol of glucose, fully dissolving, vertically placing the conductive substrate with the titanium oxide nanotube array growing on the surface into a silver ammonia solution under the condition of 40 ℃ water bath, and modifying silver nanoparticles on the surface of the titanium oxide nanotubes by utilizing a silver mirror reaction for 20 min. And after the reaction is finished, washing the surface of the conductive substrate on which the titanium oxide nanotube array modified by the silver nanoparticles grows for 1 time by using deionized water, and then airing at room temperature to prepare the titanium oxide nanotube array modified by the nano silver.

Example 2

An indium tin oxide glass substrate is selected as a conductive sinking bottom, and the preparation method comprises the following specific steps:

01. bombarding the conductive surface of the conductive substrate for 300s by utilizing plasma in an oxygen atmosphere, adding the hydrophilicity of the surface of the conductive substrate, cleaning the surface of the conductive substrate for 2 times by using deionized water after the bombardment is finished, and drying the conductive substrate in a 60 ℃ drying oven;

02. preparing a zinc oxide nanorod array: adding 100ml of water into 0.010mol of zinc nitrate hexahydrate, fully dissolving, dropwise adding 10 wt% ammonia water to clear, vertically placing the conductive substrate into a zinc-ammonia solution under the condition of 70 ℃ water bath, and growing a zinc oxide nanorod on the surface of the conductive substrate for 75 min. After the reaction is finished, the surface of the conductive substrate on which the zinc oxide nanorod array grows is washed by deionized water for 2 times, and then dried at room temperature.

03. Preparing a titanium oxide nanotube array: adding 100ml of water into 0.0075mol of ammonium fluorotitanate and 0.020mol of boric acid, fully dissolving, vertically placing the conductive substrate with the zinc oxide nanorod array growing on the surface into a fluorotitanic acid solution at room temperature, and carrying out chemical reaction for 75min to convert the zinc oxide nanorod into the titanium oxide nanotube in situ. After the reaction is finished, the surface of the conductive substrate on which the titanium oxide nanotube array grows is cleaned for 2 times by deionized water, and then dried at room temperature.

04. Preparing a titanium oxide nanotube array modified by silver nanoparticles with a closed top end: adding 100ml of water into 0.020mol of silver nitrate and 0.050mol of glucose, fully dissolving, vertically placing the conductive substrate with the titanium oxide nanotube array growing on the surface into a silver ammonia solution under the condition of 50 ℃ water bath, and modifying silver nanoparticles on the surface of the titanium oxide nanotubes by utilizing a silver mirror reaction for 25 min. And after the reaction is finished, washing the surface of the conductive substrate on which the titanium oxide nanotube array modified by the silver nanoparticles grows for 2 times by using deionized water, and then airing at room temperature to prepare the titanium oxide nanotube array modified by the nano silver.

Example 3

An indium tin oxide glass substrate is selected as a conductive substrate, and the preparation method comprises the following specific steps:

01. bombarding the conductive surface of the conductive substrate for 360 seconds by utilizing plasma in an oxygen atmosphere, adding the hydrophilicity of the surface, cleaning the bottom surface of the conductive substrate for 3 times by using deionized water after the bombardment is finished, and drying in a 60 ℃ drying oven;

02. preparing a zinc oxide nanorod array: adding 100ml of water into 0.012mol of zinc nitrate hexahydrate, fully dissolving, dropwise adding 10 wt% ammonia water to clear, vertically placing the conductive substrate into the zinc-ammonia solution under the condition of 80 ℃ water bath, and growing a zinc oxide nanorod on the surface of the conductive substrate for 90 min. After the reaction is finished, the surface of the conductive substrate on which the zinc oxide nanorod array grows is washed by deionized water for 3 times, and then dried at room temperature.

03. Preparing a titanium oxide nanotube array: adding 100ml of water into 0.0080mol of ammonium fluorotitanate and 0.025mol of boric acid, fully dissolving, vertically placing the conductive substrate with the zinc oxide nanorod array growing on the surface into a fluorotitanic acid solution at room temperature, and carrying out chemical reaction for 90min to convert the zinc oxide nanorod into the titanium oxide nanotube in situ. After the reaction is finished, the surface of the conductive substrate on which the titanium oxide nanotube array grows is cleaned for 3 times by deionized water, and then dried at room temperature.

04. The preparation of the top-closed titanium oxide nanotube array modified by the silver nanoparticles comprises the following steps: adding 100ml of water into 0.025mol of silver nitrate and 0.060mol of glucose, fully dissolving, vertically placing the conductive substrate with the titanium oxide nanotube array growing on the surface into a silver ammonia solution under the condition of 60 ℃ water bath, and modifying silver nanoparticles on the surface of the titanium oxide nanotubes by utilizing a silver mirror reaction for 30 min. And after the reaction is finished, washing the surface of the conductive substrate on which the titanium oxide nanotube array modified by the silver nanoparticles grows for 3 times by using deionized water, and then airing at room temperature to prepare the titanium oxide nanotube array modified by the nano silver.

Example 4

A silicon wafer substrate is selected as a conductive substrate, and the preparation method comprises the following specific steps:

01. bombarding the conductive surface of the conductive substrate for 300s by utilizing plasma in an oxygen atmosphere, adding the hydrophilicity of the surface of the conductive substrate, cleaning the surface of the conductive substrate for 3 times by using deionized water after the bombardment is finished, and drying the conductive substrate in a 60 ℃ drying oven;

02. preparing a zinc oxide nanorod array: adding 100ml of water into 0.010mol of zinc nitrate hexahydrate, fully dissolving, dropwise adding 10 wt% ammonia water to clear, vertically placing the conductive substrate into a zinc-ammonia solution under the condition of 80 ℃ water bath, and growing a zinc oxide nano rod on the surface of the conductive substrate for 60 min. After the reaction is finished, the surface of the conductive substrate on which the zinc oxide nanorod array grows is washed by deionized water for 3 times, and then dried at room temperature.

03. Preparing a titanium oxide nanotube array: adding 100ml of water into 0.0075mol of ammonium fluorotitanate and 0.020mol of boric acid, fully dissolving, vertically placing the conductive substrate with the zinc oxide nanorod array growing on the surface into a fluorotitanic acid solution at room temperature, and carrying out chemical reaction for 60min to convert the zinc oxide nanorod into the titanium oxide nanotube in situ. After the reaction is finished, the surface of the conductive substrate on which the titanium oxide nanotube array grows is cleaned for 3 times by deionized water, and then dried at room temperature.

04. Preparing a titanium oxide nanotube array modified by silver nanoparticles with a closed top end: adding 100ml of water into 0.020mol of silver nitrate and 0.050mol of glucose, fully dissolving, vertically placing the conductive substrate with the titanium oxide nanotube array growing on the surface into a silver ammonia solution under the condition of 50 ℃ water bath, and modifying silver nanoparticles on the surface of the titanium oxide nanotubes by utilizing a silver mirror reaction for 25 min. And after the reaction is finished, washing the surface of the conductive substrate on which the titanium oxide nanotube array modified by the silver nanoparticles grows for 3 times by using deionized water, and then airing at room temperature to prepare the titanium oxide nanotube array modified by the nano silver.

Example 5

A silicon wafer substrate is selected as a conductive substrate, and the preparation method comprises the following specific steps:

01. bombarding the conductive surface of the conductive substrate for 300s by utilizing plasma in an oxygen atmosphere, adding the hydrophilicity of the surface of the conductive substrate, cleaning the surface of the conductive substrate for 3 times by using deionized water after the bombardment is finished, and drying the conductive substrate in a 60 ℃ drying oven;

02. preparing a zinc oxide nanorod array: adding 100ml of water into 0.010mol of zinc nitrate hexahydrate, fully dissolving, dropwise adding 10 wt% ammonia water to clear, vertically placing the conductive substrate into a zinc-ammonia solution under the condition of 80 ℃ water bath, and growing a zinc oxide nano rod on the surface of the conductive substrate for 60 min. After the reaction is finished, the surface of the conductive substrate on which the zinc oxide nanorod array grows is washed by deionized water for 3 times, and then dried at room temperature.

03. Preparing a titanium oxide nanotube array: adding 100ml of water into 0.0075mol of ammonium fluorotitanate and 0.020mol of boric acid, fully dissolving, vertically placing the conductive substrate with the zinc oxide nanorod array growing on the surface into a fluorotitanic acid solution at room temperature, and carrying out chemical reaction for 90min to convert the zinc oxide nanorod into the titanium oxide nanotube in situ. After the reaction is finished, the surface of the conductive substrate on which the titanium oxide nanotube array grows is cleaned for 3 times by deionized water, and then dried at room temperature.

04. Preparing a titanium oxide nanotube array modified by silver nanoparticles with a closed top end: adding 100ml of water into 0.020mol of silver nitrate and 0.050mol of glucose, fully dissolving, vertically placing the conductive substrate with the titanium oxide nanotube array growing on the surface into a silver ammonia solution under the condition of 50 ℃ water bath, and modifying silver nanoparticles on the surface of the titanium oxide nanotubes by utilizing a silver mirror reaction for 25 min. And after the reaction is finished, washing the surface of the conductive substrate on which the titanium oxide nanotube array modified by the silver nanoparticles grows for 3 times by using deionized water, and then airing at room temperature to prepare the titanium oxide nanotube array modified by the nano silver.

The samples prepared in the examples 1 and 2 are put into a solution with a pH value of 3-6, the sample prepared in the example 3 is put into a solution with a pH value of 7, the sample prepared in the example 4 is put into a solution with a pH value of 8-11, the samples are respectively taken out after 60min, and the characteristics are carried out by a scanning electron microscope, so that the structure and the appearance of the titanium oxide nanotube array modified by the silver nanoparticles and with the closed top end are not damaged. Indicating that the structure is capable of resisting acid, neutral and alkaline environments.

The zinc oxide nanorods and the titanium oxide nanotubes prepared in example 5 were characterized by using a Scanning Electron Microscope (SEM), and the results are shown in fig. 1, wherein (a) in fig. 1 is an SEM image of the zinc oxide nanorods, and (b) is an SEM image of the titanium oxide nanotubes. The nano silver modified titanium oxide nanotube array prepared in example 5 is characterized by using a Scanning Electron Microscope (SEM), and the result is shown in fig. 2, wherein (a) in fig. 2 is an SEM image of the target product, and (b) is a high-magnification SEM image of the target product. As can be seen from fig. 1 and 2, the titanium oxide nanotubes of the product of the present application are uniformly distributed on the conductive substrate, the specific surface area is large, the silver nanoparticles are uniformly distributed on the surface of the titanium oxide nanotubes and are densely modified, and a large number of gaps or gaps exist among the silver particles, such that the prepared nano-silver modified titanium oxide nanotube array has good photocatalytic degradation performance.

The sample prepared in example 5 was placed at a concentration of 10^-5Soaking in mol/L rhodamine 6G solution for 3 hr, measuring the content of rhodamine 6G attached to the solution with laser Raman spectrometer with excitation light wavelength of 532nm, and measuring the surface enhanced Raman spectrum at 612cm^-1Intensity of peak is 55000 counts; then, the sample adsorbed with rhodamine 6G molecules is irradiated by 365nm ultraviolet light for 3 hours, and then the SERS spectrum is measured and is measured at 612cm^-1Has no peak; then placing the sample subjected to ultraviolet irradiation into a concentration of 10^-5Soaking in mol/L rhodamine 6G solution for 3 hours, measuring the content of rhodamine 6G attached to the solution after soaking, and measuring the SERS spectrum at 612cm^-1The intensity of the peak was 54900 count units. The sample is shown to have good photocatalytic degradation performance and recycling performance as a functional SERS substrate.

Taking the sample prepared in example 5 as an active substrate for surface enhanced Raman scattering, and measuring the content of rhodamine 6G with different concentrations attached to the sample by using a laser Raman spectrometer with excitation light of 532nm, so as to obtain the result shown in FIG. 3; wherein, the power of exciting light of the laser Raman spectrometer is 0.1-2mW, and the integration time is 1-30 s. As can be seen from FIG. 3, the SERS substrate using the nano-silver modified titanium oxide nanotube array as the substrate has good sensitivity to rhodamine 6G, and the lower limit of detection of rhodamine 6G can reach 1 × 10^-11moI/L。

It is apparent that those skilled in the art can make various changes and modifications to the silver nanoparticle modified top-capped titanium oxide nanotube array of the present invention, and the preparation method and use thereof, without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.