Preparation method and application of oxygen terminal hydrophobic nano-strip diamond film

Abstract

The invention relates to the technical field of diamond functional structures and preparation, and discloses a preparation method and application of an oxygen-terminated hydrophobic nano-strip diamond film, and the preparation method comprises the following steps: step 1, grinding a silicon, molybdenum or titanium substrate with nano-diamond powder for 15-30 minutes, and placing the substrate in nano-diamond turbid liquid for ultrasonic treatment for 30 minutes; and 2, taking out the substrate slice, placing the substrate slice in a reaction chamber of a chemical vapor deposition (CVD) device, and taking hydrogen, methane and hydrogen carrying trimethyl borate as raw materials. According to the preparation method of the oxygen terminal hydrophobic nano-strip diamond film, coating films such as a copper film and a gold film are not needed, and the oxygen terminal hydrophobic diamond film can be obtained only by etching a non-diamond phase under the condition that diamond and non-diamond coexist; the oxygen terminal hydrophobic diamond film is used as a hydrophobic electrode of an electrochemical sensor, is applied to electrochemical detection of an endocrine disrupter-nonyl phenol, and has the advantages of lower cost, very good sensitivity and wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of diamond functional structure and preparation, and in particular to a preparation method and application of an oxygen-terminated hydrophobic nano-strip diamond film. Background Art

[0002] Diamond is a functional material with excellent properties such as ultra-hardness, high thermal conductivity, chemical inertness, and stability. By doping it with impurities (such as boron) to make it conductive, high-performance electrochemical electrodes can be made. Functional electrodes can promote better performance through the diamond strip structure (large specific surface area, high tip removal rate, etc.). However, due to its extremely high hardness and chemical inertness, it is not easy to change the morphology of diamond through mechanical processing or wet chemical etching.

[0003] The prior art is patent application number CN114045555A, entitled "A Method for Preparing a Super-Hydrophobic Oxygen-Terminated Polycrystalline Boron-Doped Diamond Film." The disclosed preparation method involves depositing Au and Cu thin films on the surface of a boron-doped polycrystalline diamond film using ion sputtering. The resulting copper-gold-polycrystalline diamond film is then etched in an 800°C tube furnace for 80 minutes to produce a super-hydrophobic, boron-doped oxygen-terminated diamond film with a micro-nano composite structure.

[0004] However, the existing method for preparing super-hydrophobic oxygen-terminated polycrystalline boron-doped diamond film is to deposit Au and Cu films on the surface of the boron-doped polycrystalline diamond film by ion sputtering, and then place it in an 800°C tube furnace for etching for 80 minutes. This method has the advantages of complex process and high cost. Summary of the Invention

[0005] In view of the above-mentioned prior art method for preparing super-hydrophobic oxygen-terminated polycrystalline boron-doped diamond film, which uses ion sputtering to deposit Au and Cu films on the surface of the boron-doped polycrystalline diamond film, and then places it in an 800°C tube furnace for etching for 80 minutes, this method has the problems of complex process and high cost, so the present invention is proposed.

[0006] Therefore, the purpose of the present invention is to provide a method for preparing oxygen-terminated hydrophobic nanostrip diamond films, the purpose of which is to etch the non-diamond phase from the intergrowth phase of boron-containing diamond and non-diamond through a relatively simple process to prepare an oxygen-terminated hydrophobic diamond film structure, which can be used as an electrode material to construct a high-performance ultra-sensitive electrochemical sensor.

[0007] To solve the above technical problems, the present invention provides the following technical solution: a method for preparing an oxygen-terminated hydrophobic nano-strip diamond film, comprising the following steps: Step 1: Grind the silicon, molybdenum or titanium substrate with nano-diamond powder for 15-30 minutes, and then place it in a nano-diamond suspension and ultrasonicate it for 30 minutes; Step 2: Remove the substrate and place it in a reaction chamber of a chemical vapor deposition (CVD) apparatus. Using hydrogen, methane, and hydrogen carrying trimethyl borate as raw materials, with a corresponding gas flow ratio of 200:20:3-9, boron-containing diamond and a non-diamond mixed phase are grown simultaneously. Step 3: Take out the mixed phase sample and place it in air for high temperature annealing at 800°C for 20 to 60 minutes to etch away the non-diamond phase to obtain an oxygen-terminated hydrophobic nanostrip diamond film.

[0008] As a preferred embodiment of the present invention, the oxygen-terminated hydrophobic nanostrip diamond film is based on silicon, molybdenum or titanium, on which a boron-doped diamond film is grown. The surface of the diamond film is formed with strip-shaped diamonds with a strip length of 2 to 4 mm, a strip diameter of 50 to 400 nm, and a strip tip curvature radius of 10 to 50 nm. The surface of the diamond film is rough, and the surface strip density is about 6.7×10 -7 cm - 2 .

[0009] As a preferred embodiment of the present invention, the hydrophobic angle of the strip diamonds formed on the surface of the diamond film is 120°. ｏ ~130 ｏ between.

[0010] As a preferred solution of the present invention, the chemical vapor deposition device includes a microwave plasma chemical vapor deposition device, a hot filament chemical vapor deposition device, and a hot cathode chemical vapor deposition device.

[0011] As a preferred solution of the present invention, the chemical vapor deposition device is a microwave plasma chemical vapor deposition device; during the growth of boron-containing diamond and non-diamond mixed phase, the microwave power is 350W and the cavity pressure is 8KPa.

[0012] As a preferred solution of the present invention, the oxygen-terminated hydrophobic nano-strip diamond film is used as an electrochemical electrode to make chemical and biological sensors.

[0013] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The present invention does not require copper film, gold film or other coatings. Instead, an oxygen-terminated hydrophobic diamond film can be obtained by etching the non-diamond phase under the coexistence of diamond and non-diamond. The oxygen-terminated hydrophobic diamond film is used as a hydrophobic electrode in an electrochemical sensor for the electrochemical detection of the endocrine disruptor nonylphenol. This method not only reduces cost but also has excellent sensitivity and broad application prospects.

[0014] 2. The oxygen-terminated nano-diamond strips prepared in this invention have a hydrophobic structure with a hydrophobic angle of 120-130 degrees. This is because the strip-like structure on the surface of the oxygen-terminated hydrophobic diamonds and the gaps between them increase the surface roughness, significantly increasing the surface area of ​​the electrode, providing more reaction sites for detecting trace molecules. This facilitates the surface to capture more air in the gaps, and the trapped air layer contributes to increased hydrophobicity. Furthermore, the hydrophobicity of the oxygen terminals and the curvature of the strip tips facilitate sensitive detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a scanning electron microscope image of the boron-doped diamond / non-diamond mixed phase film before high-temperature annealing of the present invention; Figure 2 This is a scanning electron microscope image of the surface morphology of the oxygen-terminated hydrophobic nanostrip diamond film of the present invention; Figure 3 The present invention is a differential conventional pulse voltammogram of 4-nonylphenol solutions with different concentrations from 0.1 to 10 nM; Figure 4 This is a diagram showing the contact angle and hydrophobic angle of the oxygen-terminated hydrophobic diamond of the present invention. DETAILED DESCRIPTION

[0016] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0017] The preparation method of the oxygen-terminated hydrophobic nanostrip diamond film comprises the following steps: Step 1: Grind the silicon, molybdenum or titanium substrate with nano-diamond powder for 15-30 minutes, and then place it in a nano-diamond suspension and ultrasonicate it for 30 minutes; Step 2: Remove the substrate and place it in a reaction chamber of a chemical vapor deposition (CVD) apparatus. Using hydrogen, methane, and hydrogen carrying trimethyl borate as raw materials, with a corresponding gas flow ratio of 200:20:3-9, boron-containing diamond and a non-diamond mixed phase are grown simultaneously. Step 3: Take out the mixed phase sample and place it in air for high temperature annealing at 800°C for 20 to 60 minutes to etch away the non-diamond phase to obtain an oxygen-terminated hydrophobic nanostrip diamond film.

[0018] The oxygen-terminated hydrophobic nanostrip diamond film is based on silicon, molybdenum or titanium, on which a boron-doped diamond film is grown. The surface of the diamond film is formed with strip-shaped diamonds with a length of 2 to 4 mm, a diameter of 50 to 400 nm, and a curvature radius of 10 to 50 nm. The surface of the diamond film is rough, with a surface strip density of approximately 6.7×10 -7 cm - 2 .

[0019] The strip diamonds formed on the surface of the diamond film have a hydrophobic angle of 120 ｏ ~130 ｏ between.

[0020] The chemical vapor deposition device includes a microwave plasma chemical vapor deposition device, a hot filament chemical vapor deposition device, and a hot cathode chemical vapor deposition device.

[0021] The chemical vapor deposition device is a microwave plasma chemical vapor deposition device; during the growth of boron-containing diamond and non-diamond mixed phase, the microwave power is 350W and the cavity pressure is 8KPa.

[0022] The oxygen-terminated hydrophobic nano-strip diamond film is used as an electrochemical electrode to produce chemical and biological sensors. Example 1

[0023] Preparation of diamond film on silicon wafer substrate A 1 cm × 1 cm silicon wafer was selected as the growth substrate. The wafer was first cleaned to remove surface contaminants. To increase the nucleation density during the growth process, the growth surface was ground on diamond-coated sandpaper for 15 minutes and ultrasonically treated in diamond-coated alcohol for 0.5 hours. The wafer was then placed in a CVD reactor to deposit a boron-containing diamond / non-diamond composite film. The growth parameters used were hydrogen, methane, and hydrogen containing trimethyl borate, with a gas flow ratio of 200 sccm: 20 sccm: 3 sccm. This resulted in a mixed phase of boron-containing diamond and non-diamond, with a thickness of approximately 10–50 μm. The resulting film was then annealed at 800°C in a tube furnace for 50 minutes to remove the non-diamond phase.

[0024] In this example, a microwave plasma chemical vapor deposition device was used to deposit diamond thin films. The microwave power was 350 W, the cavity pressure was 8 KPa, the growth time was 6 hours, and the film thickness was about 30 μm. The scanning electron microscope image is shown in Figure 2. Figure 1 As shown, oxygen-terminated hydrophobic diamond film was successfully prepared after high temperature annealing, and the scanning electron microscope image is shown in Figure 2 As shown by Figure 1 It can be seen that the length of the diamond strips ranges from 2 to 4 mm, the diameter of the strips ranges from 50 to 400 nm, and the curvature radius of the strip tips ranges from 10 to 50 nm. The surface of the diamond film is rough, and the surface strip density is about 6.7×10 -7 cm - 2 . Figure 4 The contact angle diagram of the oxygen-terminated hydrophobic nano-strip diamond prepared in this example is given. Example 2

[0025] Electrochemical test for the detection of 4-nonylphenol Nonylphenol is a new type of pollutant. Even a small amount entering the body can seriously interfere with the endocrine system and greatly endanger human health. Sensitive detection is of great significance for early prevention. 4-Nonylphenol was diluted to different concentrations in phosphate buffer at pH = 7 and detected under optimal enrichment conditions (enrichment time of 300 s and enrichment potential of 0 V). Figure 3 Differential conventional pulse voltammograms of 4-nonylphenol solutions at concentrations ranging from 0.1 to 10 nM are presented. Clearly, the oxidation peak current increases with increasing 4-nonylphenol concentration, indicating that the peak current is sensitive to low concentrations of 4-nonylphenol. The calculated detection limit is 0.031 nM. This excellent detection capability is attributed to the numerous reactive sites on the diamond nanorods, the high curvature of the tip, and the hydrophobic structure that facilitates the adsorption of nonylphenol and its excellent electrocatalytic ability. Furthermore, compared to other electrodes made of mesoporous carbon, graphene nanoparticles, DNA-modified graphene, molecularly imprinted multi-nitrogen-doped graphene nanoribbons, and gold nanoparticle-modified graphene, which have detection limits of 125 nM, 30 nM, 10 nM, 8 nM, and 3 nM, respectively, the detection limit of the oxygen-terminated hydrophobic nanorod boron-doped diamond electrode of the present invention is significantly lower than those reported above. Therefore, the diamond film of the present invention is a promising electrode material for constructing high-performance, ultrasensitive electrochemical sensors. Example 3

[0026] Stability and Repeatability Testing of Oxygen-Terminated Hydrophobic Diamond Electrode for Detection of Nonylphenol The stability and reusability of an oxygen-terminated hydrophobic diamond electrode in a 10 nM 4-nonylphenol solution were demonstrated. After each experiment, the oxygen-terminated hydrophobic boron-doped diamond electrode was cleaned with isopropyl alcohol and deionized water to remove residual 4-nonylphenol. No signal was detected in the blank solution. The interval between the two tests was 24 hours. This demonstrated that after nine consecutive days of testing, the variation was less than 4.6%, demonstrating the electrode's excellent stability and reusability.

[0027] The hydrogen-terminated diamonds prepared in previous studies are generally hydrophobic, and hydrophobic electrodes are beneficial for trace detection of 4-nonylphenol. However, after electrochemical testing, the surface of the hydrogen-terminated diamond becomes oxygen-terminated, and the performance is also reduced. The oxygen-terminated hydrophobic nanostrip diamond electrode prepared in the present invention still has an oxygen-terminated surface after electrochemical testing, and the hydrophobicity does not change significantly. It is not only highly sensitive in detection, but also has better stability and repeatability. The surface is super hydrophobic and is also suitable for detecting a variety of trace hydrophobic pollutants or for anti-fouling use.

[0028] The oxygen-terminated superhydrophobic diamond interface is the main content and important innovation involved in this invention. The preparation method is simple and easy to prepare on a large scale. This research will be of great significance for the detection of low-concentration and trace chemical and biological molecules by diamond sensors in a wide range of industrial fields.

[0029] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing an oxygen-terminated hydrophobic nano-strip diamond film, characterized in that: The following steps are involved: Step 1: Grind the silicon, molybdenum or titanium substrate with nano-diamond powder for 15-30 minutes, and then place it in a nano-diamond suspension and ultrasonicate it for 30 minutes; Step 2: Remove the substrate and place it in a reaction chamber of a chemical vapor deposition (CVD) apparatus. Using hydrogen, methane, and hydrogen carrying trimethyl borate as raw materials, with a corresponding gas flow ratio of 200:20:3-9, boron-containing diamond and a non-diamond mixed phase are grown simultaneously. Step 3: Take out the mixed phase sample and place it in air for high temperature annealing at 800°C for 20 to 60 minutes to etch away the non-diamond phase to obtain an oxygen-terminated hydrophobic nanostrip diamond film.

2. The oxygen-terminated hydrophobic nanostrip diamond film according to claim 1, characterized in that: The oxygen-terminated hydrophobic nanostrip diamond film is based on silicon, molybdenum or titanium, on which a boron-doped diamond film is grown. The surface of the diamond film is formed with strip-shaped diamonds with a length of 2 to 4 mm, a diameter of 50 to 400 nm, and a curvature radius of 10 to 50 nm. The surface of the diamond film is rough, with a surface strip density of approximately 6.7×10 -7 cm - 2 .

3. The method for preparing the oxygen-terminated hydrophobic nano-strip diamond film according to claim 2, characterized in that: The strip diamonds formed on the surface of the diamond film have a hydrophobic angle of 120 ｏ ~130 ｏ between.

4. The method for preparing an oxygen-terminated hydrophobic nanostrip diamond film according to claim 1, wherein: The chemical vapor deposition device includes a microwave plasma chemical vapor deposition device, a hot filament chemical vapor deposition device, and a hot cathode chemical vapor deposition device.

5. The method for preparing the oxygen-terminated hydrophobic nano-strip diamond film according to claim 4, characterized in that: The chemical vapor deposition device is a microwave plasma chemical vapor deposition device; during the growth of boron-containing diamond and non-diamond mixed phase, the microwave power is 350W and the cavity pressure is 8KPa.

6. Use of the oxygen-terminated hydrophobic nanostrip diamond film according to claim 2 as an electrochemical electrode for making chemical and biological sensors.

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