Preparation method of nano-diamond / graphite composite film electrode with high electrochemical activity

Abstract

The invention discloses a preparation method of a nano-diamond / graphite composite film electrode with high electrochemical activity, which comprises the following steps: preparing a nano-diamond / graphite composite film electrode through hot filament chemical vapor deposition, and depositing platinum metal atoms on the surface of the composite film electrode by atomic layer deposition equipment, and then placing the composite film electrode in an H2SO4 solution, and connecting an electrochemical workstation to carry out cyclic voltammetry treatment to finally obtain a target electrode. According to the method, the electrochemical active area of the nano-diamond / graphite composite film electrode can be remarkably increased, a new thought and scheme are provided for design and preparation of the novel nano-diamond-based composite film electrode, and the method has great application prospects in the fields of electro-catalysis, electric energy storage and the like.

Description

Technical Field

[0001] The invention relates to a method for preparing a nano diamond / graphite composite film electrode with high electrochemical activity. Background Art

[0002] In recent years, the application of diamond-based thin film electrodes in the field of electrochemical catalysis has received widespread attention. Diamond-based thin film electrodes have the characteristics of wide potential window, low background current, corrosion resistance and anti-pollution, but their own electrochemical activity is weak. To solve this problem, researchers doped boron into diamond-based thin film electrodes to prepare boron-doped diamond thin film electrodes, or introduced graphite phase into diamond-based thin film electrodes to prepare nanodiamond / graphite composite thin film electrodes, but these methods still have limited effects on improving their electrochemical activity.

[0003] Platinum metal atoms have the characteristics of high catalytic activity and strong surface reactivity, which can significantly increase the reaction rate of electrochemical reactions such as oxygen reduction and hydrogen evolution, and are therefore widely used in the field of electrocatalysis. At present, the research on platinum-loaded boron-doped diamond film electrodes basically uses the method of electrodeposition to load platinum in chloroplatinic acid-based solutions on the surface of boron-doped nanodiamond films in the form of nanoparticles, which improves the electrochemical activity of the electrode in the methanol oxidation reaction to a certain extent, and can achieve the detection of dissolved hydrogen in water-based solutions and a low detection limit of 100nM H2O2. However, the platinum-loaded boron-doped diamond film prepared by the electrodeposition method has problems such as uneven thickness and distribution of platinum nanoparticles, which makes it easy for the local current density to be too high during the electrocatalytic process, resulting in local overheating and the shedding of platinum nanoparticles, reducing the catalytic efficiency and electrode life.

[0004] In order to solve this problem, the present invention uses atomic layer deposition equipment to uniformly deposit platinum metal atoms on the surface of diamond-based thin film electrodes, avoiding the agglomeration of platinum atoms into nanoparticles, which is more conducive to improving the catalytic performance of the film; and uses sulfuric acid solution to perform cyclic voltammetry treatment on the diamond-based thin film electrodes, which can effectively remove pollutants on the surface of the thin film electrodes, reduce electron transfer impedance, expose active sites, and greatly improve the electrochemical activity of NCD-G thin film electrodes. Its electrochemical activity can reach up to 4238.27μC / cm 2 Compared with the intrinsic nanodiamond / graphite composite film electrode (electrochemical active area is about 135.90μC / cm 2 ), its electrochemical active area increased by nearly 32 times, and is higher than that of ordinary graphite electrodes (electrochemical active area is about 2000μC / cm 2 ). Therefore, the nano-diamond / graphite-based composite film electrode prepared by this method has great application prospects in the fields of electrocatalysis and electrical energy storage. Summary of the invention

[0005] The present invention aims to provide a method for preparing a nano-diamond / graphite composite thin film electrode with high electrochemical activity. First, a nano-diamond / graphite composite thin film electrode is prepared by hot wire chemical vapor deposition, and then platinum metal atoms are deposited on the surface of the composite thin film electrode by atomic layer deposition equipment, and then the composite thin film electrode is placed in a H2SO4 solution and connected to an electrochemical workstation for cyclic voltammetry treatment, and finally a nano-diamond / graphite composite thin film electrode with high electrochemical activity is obtained.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a nano-diamond / graphite composite film electrode with high electrochemical activity comprises the following steps:

[0008] (1) Using a seeded single crystal silicon wafer as a substrate, a tantalum wire as a metal wire, and acetone as a carbon source, a nanodiamond / graphite composite thin film electrode was prepared by hot wire chemical vapor deposition;

[0009] The specific operation is as follows: the seeded single crystal silicon wafer is placed as a substrate in a hot wire chemical vapor deposition device, tantalum wire is used as a metal wire, acetone is used as a carbon source, and acetone is brought into the reaction chamber by bubbling high-purity hydrogen with a flow rate of 80sccm. At the same time, high-purity hydrogen with a flow rate of 200sccm is introduced, and the growth power is controlled to be 2200W, the growth pressure is 1.0kPa, and the growth time is 90min. After the growth is completed, the acetone is stopped, and the voltage is slowly reduced to 0V at a rate of 1V / min in high-purity hydrogen, so that the power is reduced to 0W, and a nano-diamond / graphite composite thin film electrode is obtained, which is named NCD-G;

[0010] The method for seeding a single crystal silicon wafer is as follows: take a diamond seeding liquid on a polishing flannel, grind the single crystal silicon wafer back and forth at the seeding liquid to grind the seeding crystal for 20 minutes, then place the ground and seeded single crystal silicon wafer in the diamond seeding liquid, ultrasonic seeding for 30 minutes, then take out the single crystal silicon wafer, wash it with deionized water, blow dry it with nitrogen, and obtain the seeded single crystal silicon wafer; wherein, the preparation method of the diamond seeding liquid is: diamond powder with a particle size of 500nm and deionized water are mixed evenly at a ratio of 1g:100mL, and ultrasonicated for 20 minutes to obtain the diamond seeding liquid;

[0011] (2) placing the nanodiamond / graphite composite thin film electrode obtained in step (1) in a chamber of an atomic layer deposition device, depositing platinum metal atoms on its surface, and obtaining a composite thin film electrode deposited with platinum metal atoms, named NCD-G-Pt;

[0012] Specifically, the conditions for depositing platinum metal atoms are as follows: trimethylmethylcyclopentadienyl platinum is used as the platinum source, deionized water is used as the reactant, and nitrogen is used as the purge gas. The sample stage temperature is set to 270°C, the preheating time is 35 minutes, the temperature of the platinum source loading bottle is 60°C, and the number of cycles is 10 to 50 times. In each cycle: the platinum source residence time is 1.5 seconds, the deionized water residence time is 1.5 seconds, and the nitrogen purge time is 15 seconds;

[0013] (3) placing the composite thin film electrode deposited with platinum metal atoms obtained in step (2) in a H2SO4 solution (preferably at a concentration of 0.5 M), and connecting it to an electrochemical workstation for cyclic voltammetry treatment, thereby obtaining the nanodiamond / graphite composite thin film electrode with high electrochemical activity, named NCD-G-Pt-CV;

[0014] The scanning range of the cyclic voltammetry treatment was -3 V to +3 V, and the scanning rate was 100 mV / s.

[0015] The key points and technical principles of this application include:

[0016] (1) Atomic layer deposition (ALD) to deposit platinum metal atoms

[0017] At present, the research on platinum-loaded diamond-based thin film electrodes basically adopts the method of electrodeposition to load the platinum in the chloroplatinic acid-based solution in the form of nanoparticles on the surface of the boron-doped nanodiamond film. The present invention adopts the ALD technology to uniformly deposit platinum metal atoms on the diamond-based thin film electrode without the phenomenon of platinum agglomeration into nanoparticles.

[0018] The present invention selects "trimethyl methylcyclopentadienyl platinum" as the platinum source because it is an organic metal compound with stable chemical properties and can remain stable under normal temperature and standard storage conditions. This stability makes it safer during handling and use. Trimethyl methylcyclopentadienyl platinum is liquid at room temperature, and ALD requires the precursor to be transported to the reaction chamber in the form of gas phase. Therefore, the temperature of the platinum source loading bottle is set to 60°C, so that the liquid platinum source "trimethyl methylcyclopentadienyl platinum" is heated and evaporated into gaseous state to meet the requirements of ALD technology.

[0019] When depositing platinum metal atoms, the sample stage temperature is set to 270°C because the precursor is not easily oxidized to platinum oxide by the reactant H2O at this temperature when the ALD technology is used. It is easier to deposit on the substrate in the form of a single platinum atom. Preheating for 35 minutes is to ensure the uniformity of the temperature in the ALD chamber.

[0020] (2) Cyclic voltammetry treatment of NCD-G-Pt thin film electrodes

[0021] The cyclic voltammetry method is used to treat the NCD-G thin film electrode with deposited platinum metal atoms, which can diffuse the platinum element on the surface of the thin film electrode, making the platinum on the surface of the thin film electrode monodisperse, thereby significantly improving the electrochemical activity of the thin film electrode itself.

[0022] At the same time, sulfuric acid solution has strong oxidizing properties, which can effectively remove pollutants on the surface of thin film electrodes, reduce electron transfer impedance, expose active sites, and effectively improve the electrochemical activity of NCD-G thin film electrodes.

[0023] The beneficial effects of the present invention are mainly reflected in:

[0024] 1. Atomic layer deposition equipment is used to deposit platinum metal atoms on nano-diamond / graphite composite film electrodes. By controlling the number of cycles during platinum deposition, the content of deposited platinum metal atoms can be more accurately controlled, with higher controllability and repeatability;

[0025] 2. Cyclic voltammetry treatment of nanodiamond / graphite composite thin film electrodes deposited with platinum metal atoms was performed in a 0.5M H2SO4 solution using an electrochemical workstation. The operation is convenient and simple, and can significantly improve the electrochemical activity of the composite thin film electrodes.

[0026] 3. The nano-diamond / graphite-based composite film electrode has high electrochemical activity, with the highest electrochemical active area of ​​4238.7μC / cm 2 Compared with the intrinsic nanodiamond / graphite composite film electrode (electrochemical active area is about 135.90μC / cm 2 ), its electrochemical activity increased by nearly 32 times, and is higher than that of ordinary graphite electrodes (electrochemical active area is about 2000.00μC / cm 2 ), which has great application prospects in the fields of electrocatalysis and electrical energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The FESEM image of NCD-G-Pt 10cycle-CV at 50,000 times of the cyclic voltammetry treatment of platinum in Example 1 for 10 cycles.

[0028] Figure 2 In Example 1, the NCD-G-Pt 10 cycle-CV treated with platinum for 10 cycles was 800-2200 cm -1 Raman spectrum of .

[0029] Figure 3 The cyclic voltammetry curve of NCD-G-Pt 10cycle-CV in Example 1, in which the platinum was treated by cyclic voltammetry for 10 cycles, is in 1M KCl solution at a scan rate of 100 mV / s.

[0030] Figure 4 The cyclic voltammetry curve of NCD-G-Pt 10cycle-CV in Example 1, which was subjected to 10 cycles of cyclic voltammetry treatment of platinum, in 1M KCl+1mM K3Fe(CN)6 solution at a scan rate of 100mV / s.

[0031] Figure 5 Nyquist plot of NCD-G-Pt 10cycle-CV in 1M KCl solution after 10 cycles of cyclic voltammetry treatment of platinum in Example 1.

[0032] Figure 6 The FESEM image of NCD-G-Pt 30cycle-CV at 50,000 times of cyclic voltammetry treatment of platinum in Example 2 for 30 cycles.

[0033] Figure 7 In Example 2, the NCD-G-Pt 30 cycle-CV treated with platinum for 30 cycles was 800-2200 cm -1 Raman spectrum of .

[0034] Figure 8 The cyclic voltammetry curve of NCD-G-Pt 30cycle-CV in Example 2, in which the number of cycles of platinum treatment by cyclic voltammetry is 30, is in 1M KCl solution at a scan rate of 100 mV / s.

[0035] Fig. 9 The cyclic voltammetry curve of NCD-G-Pt 30cycle-CV in Example 2, which was subjected to 30 cycles of cyclic voltammetry treatment of platinum, in 1M KCl+1mM K3Fe(CN)6 solution at a scan rate of 100mV / s.

[0036] Fig.10 Nyquist plot of NCD-G-Pt 30cycle-CV in 1M KCl solution after 30 cycles of cyclic voltammetry treatment of platinum in Example 2.

[0037] Fig.11 The FESEM image of NCD-G-Pt 50cycle-CV at 50,000 times of cyclic voltammetry treatment of platinum in Example 3 is 50 cycles.

[0038] Fig.12 In Example 3, the NCD-G-Pt 50 cycle-CV treated with platinum for 50 cycles was 800-2200 cm -1 Raman spectrum of .

[0039] Fig.13 The cyclic voltammetry curve of NCD-G-Pt 50cycle-CV in Example 3, in which the number of cycles of platinum treatment by cyclic voltammetry is 50, is in 1M KCl solution at a scan rate of 100 mV / s.

[0040] Fig.14 The cyclic voltammetry curve of NCD-G-Pt 50cycle-CV in Example 3, which was subjected to 50 cycles of cyclic voltammetry treatment of platinum, in 1M KCl+1mM K3Fe(CN)6 solution at a scan rate of 100mV / s.

[0041] Fig.15 Nyquist plot of NCD-G-Pt 50cycle-CV in 1M KCl solution after 50 cycles of cyclic voltammetry treatment of platinum in Example 3.

[0042] Fig.16 Cyclic voltammetry curve of the nano-diamond / graphite composite film electrode NCD-G in Comparative Example 1 in 1M KCl+1mM K3Fe(CN)6 solution at a scan rate of 100mV / s. DETAILED DESCRIPTION

[0043] The present invention is further described below by means of specific embodiments, but the protection scope of the present invention is not limited thereto.

[0044] In the following embodiments,

[0045] Hot wire chemical vapor deposition equipment, brand: Shanghai Jiaoyou Diamond Coating Co., Ltd., model: JUHFCVD001;

[0046] Atomic layer deposition equipment, brand: Shenzhen Yuansu Optoelectronics Technology Co., Ltd., model: SUPER ALDExploiter200SP;

[0047] Electrochemical workstation, brand: Shanghai Chenhua Instrument Co., Ltd., model: CHI750E.

[0048] Example 1

[0049] Diamond powder with a particle size of 500nm and deionized water are mixed evenly in a ratio of 1g:100ml, and the mixed solution is then placed in an ultrasonic cleaner for 20 minutes to evenly disperse the diamond powder in the solution to obtain a diamond seeding solution; the diamond seeding solution is taken on a polishing flannel cloth, and a single crystal silicon wafer is ground back and forth at the seeding solution for 20 minutes to grind the seeding crystal, and then the ground seeded single crystal silicon wafer is placed in the diamond seeding solution for 30 minutes of ultrasonic seeding, and then the obtained single crystal silicon wafer is washed with deionized water and blown dry with nitrogen to finally obtain a seeded single crystal silicon wafer.

[0050] The seeded single crystal silicon wafer was placed as a substrate in a hot wire chemical vapor deposition device, tantalum wire was used as the metal wire, acetone was used as the carbon source, and high-purity hydrogen with a flow rate of 80sccm was used to bring the acetone into the reaction chamber, and high-purity hydrogen with a flow rate of 200sccm was introduced, the growth power was controlled to be 2200W, the growth pressure was 1.0kPa, and the growth time was 90min; after the growth was completed, the acetone was stopped, and the voltage was slowly reduced to 0V at a rate of 1V / min in high-purity hydrogen, so that the power was reduced to 0W, and a nanodiamond / graphite composite thin film electrode was obtained, which was named NCD-G.

[0051] Then NCD-G was placed in the chamber of the atomic layer deposition equipment to deposit platinum metal atoms on the surface of the composite thin film electrode. The specific parameters were as follows: trimethylmethylcyclopentadienylplatinum was used as the platinum source, deionized water was used as the reactant, and nitrogen was used as the purge gas. The sample stage temperature was set to 270°C, the preheating time was 35 minutes, the temperature of the platinum source loading bottle was 60°C, the number of cycles was 10 times, the platinum source residence time was 1.5 seconds, the deionized water residence time was 1.5 seconds, and the nitrogen purge time was 15 seconds. A nanodiamond / graphite composite thin film electrode with platinum metal atoms deposited on the surface was obtained, which was named NCD-G-Pt 10cycle.

[0052] Place NCD-G-Pt-10cycle in 0.5M H2SO4 solution and connect it to an electrochemical workstation for cyclic voltammetry with a scanning range of -3V to 3V and a scanning rate of 100mV / s to obtain a nanodiamond / graphite composite thin film electrode with high electrochemical activity, named NCD-G-Pt 10cycle-CV.

[0053] Field emission scanning electron microscopy (FESEM) was used to observe the surface morphology of NCD-G-Pt-10cycle-CV; microscopic confocal laser Raman spectrometer (Raman) was used to detect the phase components of NCD-G-Pt-10cycle-CV; and an electrochemical workstation was used to detect the electrochemical related properties of NCD-G-Pt-10cycle-CV.

[0054] Figure 1 This is the FESEM image of NCD-G-Pt 10cycle-CV at 50,000 times magnification after cyclic voltammetry treatment of platinum for 10 times. From the image, it can be observed that irregular tiny nanoparticles and needle-shaped nanoparticles exist on the surface of NCD-G-Pt 10cycle-CV.

[0055] Figure 2The NCD-G-Pt 10cycle-CV was used to treat the platinum for 10 cycles at 800-2200 cm -1 Raman spectrum of the band. Figure 2 The Raman spectrum in the image is composed of 1140, 1250, 1332, 1350, 1470, 1580cm -1 The typical Raman spectrum of nanodiamond thin film electrode is composed of six characteristic peaks. -1 and 1470cm -1 The peak at is attributed to the sp 2 CC vibration, 1250cm -1 The peak at 1332 cm is caused by the broadened vibrational density of states of diamond clusters with smaller grain size and tetrahedral amorphous carbon. -1 The peak at 1350cm is a typical diamond characteristic peak. -1 The D peak at the graphite grain boundary is disordered or other structural defects at the sp 2 Bond stretching vibration related, 1580cm -1 The G peak at is caused by the sp 2 The hybrid CC bond vibration is generated by the formula The content of diamond phase in the thin film electrode can be calculated, where C d and C i Raman spectrum 800-2200cm -1 The integrated area of ​​the diamond peak and non-diamond phase peak in the Raman spectrum; I D / I G The value is often used to indicate the degree of defects in the graphite phase in thin film electrodes. D / I G The larger the value, the greater the degree of defects in the graphite phase in the thin film electrode; the half-peak width of the G peak can reflect the distortion of the bond length and bond angle of graphite, and is often used to indicate the degree of order of graphite inside the thin film electrode. Generally, the smaller the half-peak width of the G peak, the higher the degree of order of graphite inside the thin film electrode. Figure 2 It can be calculated that the diamond content in NCD-G-Pt 10cycle-CV is 39.47%, I D / I G The value is 1.02, and the half-peak width of the G peak is 126.71 cm -1 .

[0056] Figure 3 The cyclic voltammetry curve of NCD-G-Pt 10cycle-CV in 1M KCl solution with a scan rate of 100mV / s is shown in Figure 1. Figure 3 It can be seen that the potential window of NCD-G-Pt 10cycle-CV is 3.25V, and the background current is 20.51mA / cm 2 .

[0057] Figure 4 The cyclic voltammetry curve of NCD-G-Pt 10cycle-CV with 10 cycles of platinum treatment in 1M KCl and 1M KCl+1mM K3Fe(CN)6 solution at a scan rate of 100mV / s is shown. Figure 4 It can be seen that the electrochemical active area C of NCD-G-Pt 10cycle-CV A 4238.27μC / cm 2 Compared with the nano-diamond / graphite composite film electrode NCD-G in comparative example 1, its electrochemical activity is increased by nearly 32 times.

[0058] Figure 5 This is the Nyquist plot of NCD-G-Pt 10cycle-CV in 1M KCl solution after 10 cycles of platinum treatment by cyclic voltammetry. It can be seen from the figure that the charge transfer impedance R of NCD-G-Pt 10cycle-CV is ct It is 35.54Ω.

[0059] Example 2

[0060] Diamond powder with a particle size of 500nm and deionized water are mixed evenly in a ratio of 1g:100ml, and the mixed solution is then placed in an ultrasonic cleaner for 20 minutes to evenly disperse the diamond powder in the solution to obtain a diamond seeding solution; the diamond seeding solution is taken on a polishing flannel cloth, and a single crystal silicon wafer is ground back and forth at the seeding solution for 20 minutes to grind the seeding crystal, and then the ground seeded single crystal silicon wafer is placed in the diamond seeding solution for 30 minutes of ultrasonic seeding, and then the obtained single crystal silicon wafer is washed with deionized water and blown dry with nitrogen to finally obtain a seeded single crystal silicon wafer.

[0061] The seeded single crystal silicon wafer was placed as a substrate in a hot wire chemical vapor deposition device, tantalum wire was used as the metal wire, acetone was used as the carbon source, and high-purity hydrogen with a flow rate of 80sccm was used to bring the acetone into the reaction chamber, and high-purity hydrogen with a flow rate of 200sccm was introduced, the growth power was controlled to be 2200W, the growth pressure was 1.0kPa, and the growth time was 90min; after the growth was completed, the acetone was stopped, and the voltage was slowly reduced to 0V at a rate of 1V / min in high-purity hydrogen, so that the power was reduced to 0W, and a nanodiamond / graphite composite thin film electrode was obtained, which was named NCD-G.

[0062] Then NCD-G was placed in the chamber of the atomic layer deposition equipment to deposit platinum metal atoms on the surface of the composite thin film electrode. The specific parameters were as follows: trimethylmethylcyclopentadienylplatinum was used as the platinum source, deionized water was used as the reactant, and nitrogen was used as the purge gas. The sample stage temperature was set to 270°C, the preheating time was 35 minutes, the temperature of the platinum source loading bottle was 60°C, the number of cycles was 30 times, the platinum source residence time was 1.5 seconds, the deionized water residence time was 1.5 seconds, and the nitrogen purge time was 15 seconds. A nanodiamond / graphite composite thin film electrode with platinum metal atoms deposited on the surface was obtained, which was named NCD-G-Pt 30cycle.

[0063] Place NCD-G-Pt-30cycle in 0.5M H2SO4 solution and connect it to an electrochemical workstation for cyclic voltammetry with a scanning range of -3V to 3V and a scanning rate of 100mV / s to obtain a nanodiamond / graphite composite thin film electrode with high electrochemical activity, named NCD-G-Pt 30cycle-CV.

[0064] Field emission scanning electron microscopy (FESEM) was used to observe the surface morphology of NCD-G-Pt-30cycle-CV; microscopic confocal laser Raman spectrometer (Raman) was used to detect the phase components of NCD-G-Pt-30cycle-CV; and an electrochemical workstation was used to detect the electrochemical related properties of NCD-G-Pt-30cycle-CV.

[0065] Figure 6 This is the FESEM image of NCD-G-Pt 30cycle-CV at 50,000 times magnification after cyclic voltammetry treatment of platinum for 30 times. From the image, it can be observed that there are also many irregular tiny nanoparticles and needle-shaped nanoparticles on the surface of NCD-G-Pt 30cycle-CV.

[0066] Figure 7 The NCD-G-Pt 30cycle-CV was used to treat the platinum for 30 cycles at 800-2200 cm -1 Raman spectrum of the band. Figure 7 The Raman spectrum in the image is composed of 1140, 1250, 1332, 1350, 1470, 1580cm -1 The typical Raman spectrum of nanodiamond thin film electrode is composed of six characteristic peaks. -1 and 1470cm -1 The peak at is attributed to the sp 2 CC vibration, 1250cm -1The peak at 1332 cm is caused by the broadened vibrational density of states of diamond clusters with smaller grain size and tetrahedral amorphous carbon. -1 The peak at 1350cm is a typical diamond characteristic peak. -1 The D peak at the graphite grain boundary is disordered or other structural defects at the sp 2 Bond stretching vibration related, 1580cm -1 The G peak at is caused by the sp 2 The hybrid CC bond vibration is generated. Figure 7 It can be calculated that the diamond content in NCD-G-Pt 30cycle-CV is 39.94%, I D / I G The value is 1.01, and the half-peak width of the G peak is 121.80 cm -1 .

[0067] Figure 8 The cyclic voltammetry curve of NCD-G-Pt 30cycle-CV in 1M KCl solution with a scan rate of 100mV / s is shown in Figure 3. Figure 8 It can be seen that the potential window of NCD-G-Pt 30cycle-CV is 3.27V, and the background current is 21.08mA / cm 2 .

[0068] Fig. 9 The cyclic voltammetry curve of NCD-G-Pt 30cycle-CV with 30 cycles of platinum treatment in 1M KCl and 1M KCl+1mM K3Fe(CN)6 solution at a scan rate of 100mV / s is shown. Fig. 9 It can be seen that the electrochemical active area C of NCD-G-Pt 30cycle-CV A 4177.01μC / cm 2 Compared with the nano-diamond / graphite composite film electrode NCD-G in comparative example 1, its electrochemical activity is increased by nearly 30 times.

[0069] Fig.10 This is the Nyquist plot of NCD-G-Pt 30cycle-CV in 1M KCl solution after 30 cycles of platinum treatment by cyclic voltammetry. It can be seen from the figure that the charge transfer impedance R of NCD-G-Pt 30cycle-CV is ct It is 38.36Ω.

[0070] Example 3

[0071] Diamond powder with a particle size of 500nm and deionized water are mixed evenly in a ratio of 1g:100ml, and the mixed solution is then placed in an ultrasonic cleaner for 20 minutes to evenly disperse the diamond powder in the solution to obtain a diamond seeding solution; the diamond seeding solution is taken on a polishing flannel cloth, and a single crystal silicon wafer is ground back and forth at the seeding solution for 20 minutes to grind the seeding crystal, and then the ground seeded single crystal silicon wafer is placed in the diamond seeding solution for 30 minutes of ultrasonic seeding, and then the obtained single crystal silicon wafer is washed with deionized water and blown dry with nitrogen to finally obtain a seeded single crystal silicon wafer.

[0072] The seeded single crystal silicon wafer was placed as a substrate in a hot wire chemical vapor deposition device, tantalum wire was used as the metal wire, acetone was used as the carbon source, and high-purity hydrogen with a flow rate of 80sccm was used to bring the acetone into the reaction chamber, and high-purity hydrogen with a flow rate of 200sccm was introduced, the growth power was controlled to be 2200W, the growth pressure was 1.0kPa, and the growth time was 90min; after the growth was completed, the acetone was stopped, and the voltage was slowly reduced to 0V at a rate of 1V / min in high-purity hydrogen, so that the power was reduced to 0W, and a nanodiamond / graphite composite thin film electrode was obtained, which was named NCD-G.

[0073] Then NCD-G was placed in the chamber of the atomic layer deposition equipment to deposit platinum metal atoms on the surface of the composite thin film electrode. The specific parameters were as follows: trimethylmethylcyclopentadienylplatinum was used as the platinum source, deionized water was used as the reactant, and nitrogen was used as the purge gas. The sample stage temperature was set to 270°C, the preheating time was 35 minutes, the temperature of the platinum source loading bottle was 60°C, the number of cycles was 50 times, the platinum source residence time was 1.5 seconds, the deionized water residence time was 1.5 seconds, and the nitrogen purge time was 15 seconds. A nanodiamond / graphite composite thin film electrode with platinum metal atoms deposited on the surface was obtained, which was named NCD-G-Pt 50cycle.

[0074] Place NCD-G-Pt-50cycle in 0.5M H2SO4 solution and connect it to an electrochemical workstation for cyclic voltammetry with a scanning range of -3V to 3V and a scanning rate of 100mV / s to obtain a nanodiamond / graphite composite thin film electrode with high electrochemical activity, named NCD-G-Pt 50cycle-CV.

[0075] Field emission scanning electron microscopy (FESEM) was used to observe the surface morphology of NCD-G-Pt-50cycle-CV; microscopic confocal laser Raman spectrometer (Raman) was used to detect the phase components of NCD-G-Pt-50cycle-CV; and an electrochemical workstation was used to detect the electrochemical related properties of NCD-G-Pt-50cycle-CV.

[0076] Fig.11 This is the FESEM image of NCD-G-Pt 50cycle-CV at 50000 times after 50 cycles of platinum treatment by cyclic voltammetry. From the image, it can be observed that there are also many irregular tiny nanoparticles and needle-shaped nanoparticles on the surface of NCD-G-Pt 50cycle-CV.

[0077] Fig.12 The NCD-G-Pt 50cycle-CV was used to treat the platinum for 50 cycles at 800-2200 cm -1 Raman spectrum of the band. Fig.12 The Raman spectrum in the image is composed of 1140, 1250, 1332, 1350, 1470, 1580cm -1 The typical Raman spectrum of nanodiamond thin film electrode is composed of six characteristic peaks. -1 and 1470cm -1 The peak at is attributed to the sp 2 CC vibration, 1250cm -1 The peak at 1332 cm is caused by the broadened vibrational density of states of diamond clusters with smaller grain size and tetrahedral amorphous carbon. -1 The peak at 1350cm is a typical diamond characteristic peak. -1 The D peak at the graphite grain boundary is disordered or other structural defects at the sp 2 Bond stretching vibration related, 1580cm -1 The G peak at is caused by the sp 2 The hybrid CC bond vibration is generated. Fig.12 It can be calculated that the diamond content in NCD-G-Pt 50cycle-CV is 40.95%, I D / I G The value is 1.02, and the half-peak width of the G peak is 124.00 cm -1 .

[0078] Fig.13 The cyclic voltammetry curve of NCD-G-Pt 50cycle-CV in 1M KCl solution with a scan rate of 100mV / s is shown in Figure 5. Fig.13 It can be seen that the potential window of NCD-G-Pt 50cycle-CV is 3.39V and the background current is 14.43mA / cm 2 .

[0079] Fig.14The cyclic voltammetry curve of NCD-G-Pt 50cycle-CV with 50 cycles of platinum treatment in 1M KCl and 1M KCl+1mM K3Fe(CN)6 solution at a scan rate of 100mV / s. Fig.14 It can be seen that the electrochemical active area C of NCD-G-Pt 50cycle-CV A 3272.84μC / cm 2 Compared with the nano-diamond / graphite composite film electrode NCD-G in comparative example 1, its electrochemical activity is increased by nearly 24 times.

[0080] Fig.15 This is the Nyquist plot of NCD-G-Pt 50cycle-CV in 1M KCl solution after 50 cycles of platinum treatment by cyclic voltammetry. From the figure, we can see that the charge transfer impedance R of NCD-G-Pt 50cycle-CV is ct It is 18.93Ω.

[0081] Comparative Example 1

[0082] The experimental conditions were consistent with those in Example 1, except that platinum metal atoms were not deposited on the surface and cyclic voltammetry treatment was not performed on the surface. Fig.16 The cyclic voltammetry curve of nanodiamond / graphite composite film electrode NCD-G in 1M KCl+1mM K3Fe(CN)6 solution at a scan rate of 100mV / s. It can be seen from the figure that the electrochemical active area of ​​NCD-G is 135.90μC / cm 2 .

Claims

1. A method for preparing a nano-diamond / graphite composite film electrode with high electrochemical activity, characterized in that: The steps include: (1) Using a seeded single crystal silicon wafer as a substrate, a tantalum wire as a metal wire, and acetone as a carbon source, a nanodiamond / graphite composite thin film electrode was prepared by hot wire chemical vapor deposition; (2) placing the nano-diamond / graphite composite thin film electrode obtained in step (1) in a chamber of an atomic layer deposition device, depositing platinum metal atoms on its surface, and obtaining a composite thin film electrode deposited with platinum metal atoms; (3) Placing the composite thin film electrode deposited with platinum metal atoms obtained in step (2) in a H2SO4 solution and connecting it to an electrochemical workstation for cyclic voltammetry treatment to obtain the nanodiamond / graphite composite thin film electrode with high electrochemical activity.

2. The method for preparing the nano-diamond / graphite composite thin film electrode with high electrochemical activity as claimed in claim 1, characterized in that: The operation of step (1) is as follows: the seeded single crystal silicon wafer is placed as a substrate in a hot wire chemical vapor deposition device, tantalum wire is used as a metal wire, acetone is used as a carbon source, and acetone is brought into the reaction chamber by bubbling high-purity hydrogen with a flow rate of 80 sccm. At the same time, high-purity hydrogen with a flow rate of 200 sccm is introduced, and the growth power is controlled to be 2200 W, the growth pressure is 1.0 kPa, and the growth time is 90 min. After the growth is completed, the acetone is stopped, and the voltage is slowly reduced to 0 V at a rate of 1 V / min in high-purity hydrogen, so that the power is reduced to 0 W, thereby obtaining a nanodiamond / graphite composite thin film electrode.

3. The method for preparing the nano-diamond / graphite composite thin film electrode with high electrochemical activity as claimed in claim 1, characterized in that: In step (1), the method for seeding the single crystal silicon wafer is as follows: taking diamond seeding liquid on a polishing flannel, grinding the single crystal silicon wafer back and forth at the seeding liquid for 20 minutes, then placing the ground seeded single crystal silicon wafer in the diamond seeding liquid, ultrasonic seeding for 30 minutes, then taking out the single crystal silicon wafer, washing it with deionized water, and blowing it dry with nitrogen to obtain the seeded single crystal silicon wafer; wherein the preparation method of the diamond seeding liquid is: mixing diamond powder with a particle size of 500nm and deionized water in a ratio of 1g:100mL evenly, and ultrasonicating for 20 minutes to obtain the diamond seeding liquid.

4. The method for preparing the nano-diamond / graphite composite thin film electrode with high electrochemical activity as claimed in claim 1, characterized in that: In step (2), the conditions for depositing platinum metal atoms are as follows: trimethylmethylcyclopentadienylplatinum is used as the platinum source, deionized water is used as the reactant, and nitrogen is used as the purge gas. The sample stage temperature is set to 270°C, the preheating time is 35 minutes, the temperature of the platinum source loading bottle is 60°C, the number of cycles is 10 to 50 times, and in each cycle: the platinum source residence time is 1.5 seconds, the deionized water residence time is 1.5 seconds, and the nitrogen purge time is 15 seconds.

5. The method for preparing the nano-diamond / graphite composite thin film electrode with high electrochemical activity as claimed in claim 1, characterized in that: In step (3), the concentration of H2SO4 solution is 0.5M.

6. The method for preparing the nano-diamond / graphite composite thin film electrode with high electrochemical activity as claimed in claim 1, characterized in that: In step (3), the scanning range of the cyclic voltammetry treatment is -3V to +3V, and the scanning rate is 100mV / s.

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