A noble metal-based thin film / carbon composite catalytic electrode and its preparation method

Abstract

The present invention discloses a noble metal-based thin film / carbon composite catalytic electrode and a preparation method thereof. The macroscopic structure main body of the composite catalytic electrode is a carbon rod, and the catalytic active substances Pt / 3R-IrO2 are deposited on the surface of the carbon rod in the form of a composite thin film. The carbon rod, the 3R-phase IrO2 film layer, and the Pt nanoparticles are firmly combined together to form an electrode material that is macroscopically in the shape of a solid rod. The preparation process mainly undergoes three processes: the first step is the deposition process of the IrO2 precursor thin film; the second step is the formation process of the 3R-phase IrO2 bulk thin film; the third step is the deposition process of the Pt nanoparticles. Due to the high intrinsic oxygen evolution catalytic activity of the 3R-phase IrO2, the high intrinsic hydrogen evolution catalytic activity of Pt, and the integrated electrode form, the composite catalytic electrode exhibits excellent hydrogen evolution / oxygen evolution dual catalytic activity and good working stability, and can be directly used as both the anode and the cathode in the process of electrolytic water hydrogen production.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic materials, and relates to a catalytic electrode composed of a composite of a thin film of a noble metal-based substance and a carbon material and a preparation method thereof. Background Art

[0002] High-efficiency and clean hydrogen energy is a typical representative of new energy. However, the natural state of H2 has extremely low reserves, and how to efficiently and abundantly obtain H2 is a hot topic of concern today. The electrolytic water hydrogen production technology is a recognized sustainable hydrogen production method, but this technology still faces the problem of low energy conversion efficiency.

[0003] There are two half-reactions in the process of electrolytic water hydrogen production, namely the hydrogen evolution reaction (HER) occurring at the cathode and the oxygen evolution reaction (OER) occurring at the anode. The occurrence of these two half-reactions is based on the interfacial transfer of electrons. Both HER and OER are multi-step reaction processes, and each reaction step has a process potential barrier, and a certain reaction overpotential is required to overcome the reaction kinetic barrier formed by the process potential barrier. Among them, HER is a two-electron reaction, while OER is a four-electron reaction. The reaction kinetic process of OER is slower than that of HER. Relatively speaking, OER requires a higher overpotential to overcome the potential barrier of its reaction process. Therefore, how to effectively reduce the reaction overpotential to improve the energy conversion efficiency is an urgent problem to be solved in the electrolytic water hydrogen production technology. Developing a catalytic electrode with high hydrogen evolution / oxygen evolution catalytic activity and long-term stable catalytic activity is one of the main ways to solve this problem.

[0004] Noble metal-based substances have extremely high electrolytic water catalytic activity. For example, Pt has high hydrogen evolution catalytic activity, and IrO2 has high oxygen evolution catalytic activity. However, noble metal-based substances are expensive, and the economic cost during industrial application is relatively high. Effectively increasing the specific surface area of noble metal substances and then improving their mass utilization rate is an important way to reduce the economic cost. Nanostructuring or thin-filming noble metal substances is a feasible means to achieve the above approach.

[0005] For OER, which requires a relatively higher overpotential to overcome the potential barrier of its reaction process, the intrinsic oxygen evolution catalytic activity of commercially available rutile-phase IrO2 is higher than that of other commercial catalysts, but it is not very ideal and there is still a large room for improvement. In 2021, the academic community reported a new type of 3R-phase IrO2, whose lattice structure and atomic arrangement are completely different from those of commercially available rutile-phase IrO2. The intrinsic oxygen evolution catalytic activity of this "ene-like" structure 3R-phase IrO2 is significantly higher than that of commercially available rutile-phase IrO2. Of course, the macroscopic form of 3R-phase IrO2 that can be prepared by the currently reported preparation methods is nano-powder, and other macroscopic forms of 3R-phase IrO2 such as thin films cannot be prepared yet.

[0006] Meanwhile, the multifunctionalization of catalytic electrodes is also the goal pursued by the industry today. A catalytic electrode with multiple catalytic functions can be applied to different catalytic reaction processes, which can not only improve the utilization efficiency of the electrode but also reduce the maintenance cost of the electrolyzer. For example, a catalytic electrode with both hydrogen evolution / oxygen evolution catalytic functions can be used for both the cathode and anode in the process of water electrolysis for hydrogen production, which can reduce the working costs in the processes of electrode selection, electrode maintenance, and electrode replacement in the electrolyzer. Functional compounding is a feasible means to achieve the multifunctionalization of catalytic electrodes, that is, substances with different catalytic functions are compounded to independently play their catalytic activity roles in different catalytic links.

[0007] In addition, traditional electrolytic water catalytic materials often appear in powder form and need to be mixed with a polymer binder to form a slurry, and then coated on the surface of a conductive substrate to form an electrode for work. However, in the actual process of electrolytic water, such catalytic electrodes often cannot achieve the expected catalytic effect. The main reasons are as follows: (1) The presence of the polymer binder increases the internal resistance of the electrode and reduces the conductivity of the electrode; (2) The polymer binder will mask some catalytic active sites of the catalytic material, resulting in insufficient catalytic activity; (3) The powdered catalytic material is connected to the substrate surface through the polymer binder, and the binding force with the substrate is poor, and it is easy to fall off during the electrolytic water process, resulting in reduced catalytic stability. In addition, the use and coating process of the polymer binder further increase the production cost of the electrode.

[0008] If the catalytic active substance is in-situ deposited and fixed in the form of a film or the like on a conductive carrier with a specific macroscopic physical form and stable chemical properties of its own to form a stable structure-integrated catalytic electrode, it can be directly used in the electrolysis process. It can not only omit the electrode preparation process of the slurry-coating process but also avoid the negative effects brought by the use of polymer binders.

[0009] Carbon rod materials have high electrical conductivity, chemical stability, light weight, and low price, and have been widely recognized as conductive carriers for electrodes. Constructing a special noble metal-based thin film substance with high-efficiency hydrogen evolution / oxygen evolution dual catalytic activity on the surface of the carbon rod material, the formed catalytic electrode can be used as both the anode and the cathode in the process of water electrolysis for hydrogen production. Summary of the Invention

[0010] In order to overcome the deficiencies of the prior art, the present invention provides a noble metal-based thin film / carbon composite catalytic electrode that can be used as both an anode catalytic electrode and a cathode catalytic electrode in the process of water electrolysis for hydrogen production, and a preparation method thereof.

[0011] The technical solution adopted by the present invention to solve its technical problems is:

[0012] A noble metal-based thin film / carbon composite catalytic electrode, comprising:

[0013] A carbon rod substrate, Pt / 3R-IrO 2 Composite thin film;

[0014] Specifically, the Pt / 3R-IrO 2 Composite thin film is deposited and fixed on the surface of the carbon rod substrate, and the Pt / 3R-IrO 2 Composite thin film serves as the catalytic active substance, and the carbon rod serves as the conductive carrier of the electrode;

[0015] Among them, the Pt / 3R-IrO 2 Composite thin film is a composite of 3R-phase IrO 2 Thin film and Pt nanoparticles;

[0016] Furthermore, the Pt nanoparticles are dispersedly deposited on the surface layer of the 3R-phase IrO 2 Film layer.

[0017] For the above composite catalytic electrode, the main body of its macroscopic structure is a carbon rod, and the catalytic active substance Pt / 3R-IrO 2 Is deposited on the surface of the carbon rod in the form of a composite thin film, and the carbon rod, 3R-IrO 2 Film layer, and Pt nanoparticles are firmly combined together to form an electrode material in the shape of a solid rod macroscopically. The 3R-IrO 2 Film layer has a very high intrinsic oxygen evolution catalytic activity, and the Pt nanoparticles have a very high intrinsic hydrogen evolution catalytic activity. The combination of the two makes the Pt / 3R-IrO 2 Composite thin film have excellent dual catalytic activities of hydrogen evolution / oxygen evolution at the same time. Since the 3R-IrO 2 Film layer is formed in situ on the surface of the carbon rod, and then the Pt nanoparticles are in-situ deposited on the surface layer of the 3R-IrO 2 Film layer. On the one hand, the surface layer of the Pt / 3R-IrO 2 Composite thin film has a micro-nano structure, which is beneficial to improving the apparent catalytic activity of the electrode. On the other hand, this integrated electrode form can inhibit the agglomeration and shedding of the catalytic active substance during the operation of the electrode, thereby improving the stability of the electrode. In addition, the carbon rod material itself has stable chemical properties and high conductivity. The Pt / 3R-IrO 2 Composite thin film is in direct contact with the carbon material without using a polymer binder, which is beneficial to reducing the internal resistance of the electrode and avoiding other negative impacts brought about by the use of the binder.

[0018] The present invention also provides a preparation method for the above composite catalytic electrode.

[0019] A preparation method for a noble metal-based thin film / carbon composite catalytic electrode, comprising the following process:

[0020] First step, deposition process of IrO 2 precursor thin film.

[0021] Deposit the IrO 2 precursor thin film by DC magnetron reactive sputtering, and the specific operation is as follows:

[0022] Use a high-purity metal Ir (iridium) target as the target and a carbon rod as the substrate, and perform sputtering in an Ar / O 2 mixed atmosphere.

[0023] After evacuating the equipment to less than 8×10 -6 mbar, introduce Ar gas with a purity of 99.999%. When the pressure in the equipment reaches about 6×10 -3 mbar, turn on the bias power supply and perform reverse sputtering ion etching on the carbon rod for 3 - 10 min. The bias voltage used for reverse sputtering ion etching is 50 - 100 V. Then introduce the Ar / O 2 mixed gas. When the pressure in the equipment reaches 7×10 -3 ~9×10 -3 mbar, perform reactive sputtering deposition of the IrO 2 precursor thin film. The deposition bias voltage is -60~-30 V, the sputtering power is 40~200 W, the substrate temperature is 25~160 °C, and the deposition time is 20~90 min.

[0024] During the above sputtering process, the gas volume ratio of the Ar / O 2 mixed atmosphere is Ar:O 2 =1:5~1:8.5.

[0025] After sputtering is completed, take out the carbon rod with the IrO 2 precursor thin film deposited on its surface, clean it with ethanol, and then vacuum dry it at room temperature. The product is marked as a-IrO 2 / C.

[0026] Second step, formation process of 3R-phase IrO 2 bulk thin film.

[0027] Put the a-IrO 2 / C obtained in the previous step into an alkaline molten salt bath, and under the protection of an Ar atmosphere, perform heat preservation treatment for 1.5 - 3 h. After the treatment is completed, take it out. After the temperature slowly drops to room temperature, wash it repeatedly with deionized water and ethanol. Then, soak it in HCl (hydrochloric acid) solution for 2 - 5 h. After that, wash it repeatedly with deionized water again and vacuum dry it at room temperature.

[0028] The molten salt composition of the above alkaline molten salt bath is Na 2 CO 3(Sodium carbonate) and LiOH (Lithium hydroxide), Na 2 CO 3 The mass ratio of and LiOH is Na 2 CO 3 :LiOH = 8:1 to 20:1, and the temperature of the molten salt bath is 850 to 1050 °C.

[0029] The mass content of HCl in the above HCl solution is 10 to 35%.

[0030] After the above treatment process, the IrO 2 precursor film originally deposited on the surface of the carbon rod is transformed into a 3R-phase IrO 2 film, and the product is labeled 3R-IrO 2 / C.

[0031] The third step is the deposition process of Pt nanoparticles.

[0032] Deposit Pt nanoparticles on the surface of the 3R-phase IrO 2 film by DC magnetron sputtering, and the specific operation is as follows:

[0033] The target is a high-purity metal Pt (platinum) target, and the substrate is 3R-IrO 2 / C, and sputtering is carried out in an Ar atmosphere.

[0034] After evacuating the equipment to less than 8×10 -6 mbar, introduce Ar gas with a purity of 99.999%, and when the pressure in the equipment reaches 6×10 -4 ~1×10 -3 mbar, sputter-deposit Pt nanoparticles, the deposition bias voltage is -80 to -40 V, the sputtering power is 30 to 100 W, the substrate temperature is room temperature, and the deposition time is 4 to 15 min.

[0035] After sputtering is completed, take out the product and bake it in an air atmosphere at 200 to 280 °C for 0.5 to 2 h. After baking, cool it naturally to room temperature to obtain the final product. The final product is labeled Pt / 3R-IrO 2 / C.

[0036] The above Pt / 3R-IrO 2 / C can be used as a composite catalytic electrode and directly used as the hydrogen evolution electrode and oxygen evolution electrode for electrolytic water to produce hydrogen.

[0037] The beneficial effects of the present invention are: The macroscopic structure main body of the present invention is a carbon rod, and the catalytic active substance Pt / 3R-IrO 2 is deposited on the surface of the carbon rod in the form of a composite film, and the carbon rod, 3R-phase IrO 2The film layer, Pt nanoparticles, and [object not clear] are firmly combined together to form an electrode material in the shape of a solid rod on a macroscopic scale. Its preparation process mainly goes through three steps: The first step is the deposition process of the precursor film; the second step is the formation process of the 3R-phase [object not clear] bulk film; the third step is the deposition process of Pt nanoparticles. Thanks to the high intrinsic oxygen evolution catalytic activity of the 3R-phase [object not clear], the high intrinsic hydrogen evolution catalytic activity of Pt, and the integrated electrode structure, this composite catalytic electrode exhibits excellent dual hydrogen evolution / oxygen evolution catalytic activity and good working stability, and can be directly used as both the anode and the cathode in the process of water electrolysis for hydrogen production. 2 The deposition process of the precursor film; 2 The formation process of the 3R-phase [object not clear] bulk film; 2 The deposition process of Pt nanoparticles. Thanks to the high intrinsic oxygen evolution catalytic activity of the 3R-phase [object not clear], the high intrinsic hydrogen evolution catalytic activity of Pt, and the integrated electrode structure, this composite catalytic electrode exhibits excellent dual hydrogen evolution / oxygen evolution catalytic activity and good working stability, and can be directly used as both the anode and the cathode in the process of water electrolysis for hydrogen production. Description of the Drawings

[0038] The present invention will be further described below in conjunction with the drawings and embodiments.

[0039] Figure 1 This is a SEM photograph of the surface of the composite catalytic electrode (Pt / 3R-[object not clear] / C-1) prepared according to the present invention. The Pt / 3R-[object not clear] composite film adheres to the surface of the carbon rod densely and smoothly. 2 The Pt / 3R-[object not clear] composite film adheres to the surface of the carbon rod densely and smoothly. 2 The Pt / 3R-[object not clear] composite film adheres to the surface of the carbon rod densely and smoothly.

[0040] Figure 2 This is the XRD diffraction pattern of the Pt / 3R-[object not clear] composite film on the surface of the composite catalytic electrode (Pt / 3R-[object not clear] / C-1) prepared according to the present invention. The composite film is composed of 3R-phase [object not clear] and face-centered cubic phase Pt. 2 The Pt / 3R-[object not clear] composite film on the surface of the composite catalytic electrode (Pt / 3R-[object not clear] / C-1) prepared according to the present invention. 2 The Pt / 3R-[object not clear] composite film on the surface of the composite catalytic electrode (Pt / 3R-[object not clear] / C-1) prepared according to the present invention. 2 The composite film is composed of 3R-phase [object not clear] and face-centered cubic phase Pt.

[0041] Figure 3 This is the HRTEM photograph of the Pt / 3R-[object not clear] composite film on the surface of the composite catalytic electrode (Pt / 3R-[object not clear] / C-1) prepared according to the present invention, showing the lattice fringes of the (0003) crystal plane of 3R-phase [object not clear] and the (111) crystal plane of face-centered cubic phase Pt. 2 The Pt / 3R-[object not clear] composite film on the surface of the composite catalytic electrode (Pt / 3R-[object not clear] / C-1) prepared according to the present invention. 2 The Pt / 3R-[object not clear] composite film on the surface of the composite catalytic electrode (Pt / 3R-[object not clear] / C-1) prepared according to the present invention. 2 Showing the lattice fringes of the (0003) crystal plane of 3R-phase [object not clear] and the (111) crystal plane of face-centered cubic phase Pt. Detailed Embodiments

[0042] The technical solutions in the embodiments of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0043] Unless otherwise specified, the substances used in the embodiments of the present invention are all available in the free market.

[0044] Example 1

[0045] IrO 2 Deposition process of the precursor film:

[0046] Deposit IrO 2 precursor film by DC magnetron reactive sputtering. Select the target as a high-purity metal Ir (iridium) target and the substrate as a carbon rod, and perform sputtering in an Ar / O 2 mixed atmosphere. Pump the equipment to a vacuum below 8×10 -6 mbar, then introduce Ar gas with a purity of 99.999%. When the pressure in the equipment reaches about 6×10 -3 mbar, turn on the bias power supply and perform reverse sputtering ion etching on the carbon rod for 6 min. The bias voltage used for reverse sputtering ion etching is 80 V. Then introduce the Ar / O 2 mixed gas (the gas volume ratio of Ar:O 2 =1:6.5). When the pressure in the equipment reaches about 7.5×10 -3 mbar, perform reactive sputtering deposition of the IrO 2 precursor film. The deposition bias voltage is -50 V, the sputtering power is 120 W, the substrate temperature is 140 °C, and the deposition time is 60 min. After sputtering, take out the product, wash it with ethanol, and then dry it in vacuum at room temperature.

[0047] Formation process of the 3R-phase IrO 2 bulk film:

[0048] Put the product obtained in the previous step into an alkaline molten salt bath at 900 °C (the mass ratio of Na 2 CO 3 and LiOH is Na 2 CO 3 :LiOH = 12:1), and perform heat preservation treatment for 2.5 h under Ar atmosphere protection. After the treatment is completed, take it out. After the temperature slowly drops to room temperature, wash it repeatedly with deionized water and ethanol. Then, soak it in an HCl solution (the mass content of HCl is 20%) for 4 h. After that, wash it repeatedly with deionized water again and dry it in vacuum at room temperature.

[0049] Deposition process of Pt nanoparticles:

[0050] Deposit Pt nanoparticles on the surface of the product obtained in the previous step by DC magnetron sputtering. The target is a high-purity metal Pt (platinum) target and the substrate is the product obtained in the previous step, and perform sputtering in an Ar atmosphere. Pump the equipment to a vacuum below 8×10 - 6 mbar, then introduce Ar gas with a purity of 99.999%. When the pressure in the equipment reaches 8.5×10 -4Sputtering deposition of Pt nanoparticles was carried out at around mbar, with a deposition bias voltage of -60 V, a sputtering power of 60 W, a substrate temperature of room temperature, and a deposition time of 10 min. After sputtering, the product was taken out and baked at 220 °C in an air atmosphere for 1.5 h. After baking, it was naturally cooled to room temperature to obtain the final product.

[0051] This final product was labeled Pt / 3R-IrO 2 / C-1.

[0052] Example 2

[0053] IrO 2 Deposition process of the precursor film: The same as in Example 1.

[0054] 3R-phase IrO 2 Formation process of the bulk film:

[0055] The implementation steps were the same as in Example 1. The temperature of the alkaline molten salt bath was 1000 °C, and the mass ratio of Na 2 CO 3 and LiOH in the molten salt composition was Na 2 CO 3 :LiOH = 18:1. It was heat-treated for 3 h under the protection of an Ar atmosphere. After the treatment, it was taken out. After the temperature slowly dropped to room temperature, it was repeatedly washed with deionized water and ethanol. Then, it was immersed in an HCl solution (the mass content of HCl was 20%) for 5 h. After that, it was repeatedly washed with deionized water again and vacuum-dried at room temperature.

[0056] Deposition process of Pt nanoparticles: The same as in Example 1.

[0057] This final product was labeled Pt / 3R-IrO 2 / C-2.

[0058] Example 3

[0059] IrO 2 Deposition process of the precursor film: The same as in Example 1.

[0060] 3R-phase IrO 2 Formation process of the bulk film: The same as in Example 1.

[0061] Deposition process of Pt nanoparticles:

[0062] The implementation steps were the same as in Example 1. The target was a high-purity metal Pt (platinum) target, and the substrate was the product obtained in the previous step. Sputtering was carried out in an Ar atmosphere. After evacuating the equipment to less than 8×10 -6 mbar, Ar gas with a purity of 99.999% was introduced, and the gas pressure in the equipment reached 6.5×10 -3Sputtering deposition of Pt nanoparticles was carried out at around mbar, with a deposition bias of -40 V, a sputtering power of 40 W, a substrate temperature at room temperature, and a deposition time of 6 min. After sputtering, the product was taken out and baked at 260 °C in an air atmosphere for 0.8 h. After baking, it was naturally cooled to room temperature to obtain the final product.

[0063] This final product was labeled as Pt / 3R-IrO 2 / C-3.

[0064] Example 4

[0065] IrO 2 Deposition process of the precursor film: The same as in Example 1.

[0066] 3R-phase IrO 2 Formation process of the bulk film: The same as in Example 2.

[0067] Deposition process of Pt nanoparticles: The same as in Example 3.

[0068] This final product was labeled as Pt / 3R-IrO 2 / C-4.

[0069] Characterization and analysis

[0070] The composite catalytic electrodes obtained in the above examples were analyzed by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HETEM), and X-ray diffraction (XRD). The XRD analysis results (phase analysis structure) are shown in Table 1. The SEM photos, HETEM photos, and XRD diffraction patterns of the Pt / 3R-IrO 2 / C-1 sample are shown in the attached Figures 1 to 3 .

[0071] Performance analysis

[0072] Hydrogen evolution overpotential (η c ) and oxygen evolution overpotential (η a ) tests:

[0073] Using a three-electrode system, the above composite catalytic electrodes Pt / 3R-IrO 2 / C-1 to 4 were used as the working electrode, metallic platinum as the corresponding counter electrode, and a saturated calomel electrode as the reference electrode. In a 0.5 mol·L -1 H 2 SO 4 solution, after continuous electrolysis for 1 min at a current density of -10 mA·cm -2 or +10 mA·cm -2 , the hydrogen evolution overpotential (η c-1 ) and oxygen evolution overpotential (η a-1 were read at this moment.). The test results are shown in Table 1.

[0074] Stability test:

[0075] Using a three - electrode system, the above - mentioned composite catalytic electrode Pt / 3R - IrO 2 / C - 1~4 was used as the working electrode, metallic platinum as the corresponding counter electrode, and a saturated calomel electrode as the reference electrode. In a 0.5 mol·L -1 H 2 SO 4 solution, at a current density of - 10 mA·cm -2 or + 10 mA·cm -2 , after continuous electrolysis for 1440 min, the hydrogen evolution overpotential (η c-1440 ) and oxygen evolution overpotential (η a-1440 ) at this moment were read. The test results are shown in Table 1.

[0076] The stability was evaluated by the average change rate of the hydrogen evolution overpotential and oxygen evolution overpotential: change rate = [(η c-1140 - η c-1 ) / η c-1 + (η a-1140 - η a-1 ) / η a-1 / 2×100%. The average change rate results are shown in Table 1.

[0077] Table 1 Physical phases and performance test results of the composite catalytic electrode

[0078] catalytic electrode phase <![CDATA[η c-1 (V)]]> <![CDATA[η c-1440 (V)]]> <![CDATA[η a-1 (V)]]> <![CDATA[η a-1440 (V)]]> average change rate of overpotential carbon rod graphite C 0.461 0.492 0.582 0.643 8.59% <![CDATA[Pt / 3R-IrO 2 / C-1]]> <![CDATA[Face-centered cubic phase Pt, 3R phase IrO 2 > 0.016 0.017 0.223 0.225 3.57% <![CDATA[Pt / 3R-IrO 2 / C-2]]> <![CDATA[Face-centered cubic phase Pt, 3R phase IrO 2 > 0.018 0.019 0.244 0.248 3.58% <![CDATA[Pt / 3R-IrO 2 / C-3]]> <![CDATA[Face-centered cubic phase Pt, 3R phase IrO 2 > 0.031 0.032 0.312 0.319 2.74% <![CDATA[Pt / 3R-IrO 2 / C-4]]> <![CDATA[Face-centered cubic phase Pt, 3R phase IrO 2 > 0.025 0.027 0.33 0.336 4.45%

[0079] As can be seen from Table 1, the hydrogen evolution overpotential (η c ) and oxygen evolution overpotential (η a- ) of Examples 1 - 4 are both small, indicating that the composite catalytic electrode provided by the present invention can significantly accelerate the processes of hydrogen evolution reaction and oxygen evolution reaction, and improve the energy conversion efficiency of hydrogen production by electrolyzing water; after continuous electrolysis for 1440 min at a current density of - 10 mA·cm -2 or + 10 mA·cm -2 , the average change rates of the hydrogen evolution overpotential and oxygen evolution overpotential of Examples 1 - 4 are both < 4.5%, further proving that the composite catalytic electrode provided by the present invention has good working stability.

[0080] The technical features of the above - mentioned embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above - mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0081] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A preparation method of a noble metal-based thin film / carbon composite catalytic electrode, the noble metal-based thin film / carbon composite catalytic electrode comprising a carbon rod substrate and a Pt / 3R-IrO 2 composite thin film deposited and fixed on the surface of the carbon rod substrate, and serving as a hydrogen evolution electrode and an oxygen evolution electrode for electrolytic water hydrogen production; the Pt / 3R-IrO 2 composite thin film is a catalytic active substance, and the carbon rod substrate is a conductive carrier of the electrode; It is characterized in that The steps are as follows: Step 1: Deposition process of IrO 2 precursor thin film; Deposit the IrO 2 precursor thin film by DC magnetron reactive sputtering, and the specific operations are as follows: The target is a high-purity metal Ir target, and the substrate is a carbon rod. Sputtering is carried out in an Ar / O 2 mixed atmosphere; The device is evacuated to less than 8×10 -6 mbar, and then Ar gas with a purity of 99.999% is introduced. When the pressure in the device reaches 6×10 -3 mbar, the bias power supply is turned on, and the carbon rod is subjected to reverse sputtering ion etching for 3 - 10 min. The bias voltage used for reverse sputtering ion etching is 50 - 100 V. Then, an Ar / O 2 mixed gas is introduced. When the pressure in the device reaches 7×10 -3 - 9×10 -3 mbar, reactive sputtering deposition of the IrO 2 precursor film is carried out. The deposition bias voltage is - 60 to - 30 V, the sputtering power is 40 - 200 W, the substrate temperature is 25 - 160 °C, and the deposition time is 20 - 90 min; During the above sputtering process, the gas volume ratio of the Ar / O 2 mixed atmosphere is Ar:O 2 = 1:5 to 1:8.5; After sputtering, the carbon rod with the IrO 2 precursor thin film deposited on its surface was taken out, washed with ethanol, and dried in vacuum at room temperature. The product was labeled as a-IrO 2 / C; Step 2: Formation process of 3R-phase IrO 2 bulk thin film; Put the a-IrO 2 / C obtained in the previous step into an alkaline molten salt bath, keep it warm for 1.5 - 3 h under the protection of an Ar atmosphere, take it out after the treatment is completed, wait for the temperature to slowly drop to room temperature, then wash it repeatedly with deionized water and ethanol, and then soak it in an HCl solution for 2 - 5 h. After that, wash it repeatedly with deionized water again and dry it under vacuum at room temperature; The molten salt composition of the above-mentioned alkaline molten salt bath is Na 2 CO 3 and LiOH, and the mass ratio of Na 2 CO 3 to LiOH is Na 2 CO 3 :LiOH = 8:1 to 20:1, and the temperature of the molten salt bath is 850 to 1050 °C; The mass content of HCl in the above HCl solution is 10-35%; After the above treatment process, the IrO precursor film originally deposited on the surface of the carbon rod is transformed into a 3R-phase IrO film, and the product is labeled as 3R-IrO / C; 2 2 2 ​​​ The third step is the deposition process of Pt nanoparticles; Deposit Pt nanoparticles on the surface of the 3R-phase IrO 2 thin film by DC magnetron sputtering, and the specific operation steps are as follows: The target material is a high-purity metal Pt target, and the substrate is 3R-IrO 2 / C, and sputtering is carried out in an Ar atmosphere; The device was evacuated to less than 8×10 -6 mbar, and then Ar gas with a purity of 99.999% was introduced. When the pressure inside the device reached 6×10 -4 ~1×10 -3 mbar, Pt nanoparticles were deposited by sputtering. The deposition bias voltage was -80 to -40 V, the sputtering power was 30 to 100 W, the substrate temperature was at room temperature, and the deposition time was 4 to 15 min; After sputtering is completed, take out the product and bake it in an air atmosphere at 200 - 280 °C for 0.5 - 2 h. After baking, let it cool naturally to room temperature to obtain the final product, which is labeled as Pt / 3R-IrO 2 / C.

2. According to the method for preparing a noble metal-based thin film / carbon composite catalytic electrode described in claim 1, It is characterized in that The Pt / 3R-IrO 2 composite film is a composite of 3R-phase IrO 2 film and Pt nanoparticles, and the Pt nanoparticles are dispersedly deposited on the surface layer of the 3R-phase IrO 2 film layer.

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