A nano-carbon material-assisted electroless plating platinum composite coating and its preparation method

Abstract

The present invention relates to the technical field of electroless platinum composite coatings, and specifically to a nano-carbon material-assisted electroless platinum composite coating and its preparation method. It is composed of the following components by weight: 5-10 parts of hexachloroplatinic acid; 15-25 parts of ethylenediamine; 0.5-2 parts of graphene nanosheets; 0.5-2 parts of single-walled carbon nanotubes; 1-3 parts of polyvinylpyrrolidone; 3-8 parts of sodium borohydride; 0.1-0.5 parts of sodium dodecylbenzenesulfonate; 0.5-2 parts of 3-mercaptopropyltrimethoxysilane; 5-10 parts of trisodium citrate; and the balance is deionized water. By cleverly introducing graphene nanosheets and single-walled carbon nanotubes into the electroless platinum system, the synergistic effect of the two nano-carbon materials forms a unique three-dimensional conductive network, which not only effectively disperses and fixes platinum nanoparticles, but also significantly improves the conductivity and mechanical strength of the coating; greatly enhances the adhesion and corrosion resistance of the coating.

Description

Technical Field

[0001] The present invention relates to the technical field of electroless platinum composite coatings, and specifically to a nano-carbon material-assisted electroless platinum composite coating and a preparation method thereof. Background Art

[0002] With the rapid development of modern industrial technology, the requirements for material properties are increasing day by day. Among many advanced materials, electroless platinum coatings have attracted much attention due to their excellent catalytic performance, good corrosion resistance and high-temperature stability. However, traditional electroless platinum technologies still face many challenges in practical applications.

[0003] Firstly, conventional electroless platinum coatings often have problems such as uneven structure and poor adhesion. This is mainly because during the deposition process, platinum nanoparticles are prone to agglomeration, resulting in an increase in the surface roughness of the coating, which in turn affects its mechanical properties and service life. Secondly, the conductivity and electrocatalytic activity of traditional coatings often fail to meet the requirements of high-performance electrochemical devices. Especially in fields such as fuel cells, how to improve the utilization rate and catalytic efficiency of platinum has always been a hot topic and a difficult point in research.

[0004] In addition, in high-temperature application environments, ordinary electroless platinum coatings are prone to sintering and phase transformation, resulting in a sharp decline in their performance. This problem seriously restricts the application of platinum-based coatings in high-temperature fields such as aerospace and energy. At the same time, in corrosive environments, the insufficient bonding force between the coating and the substrate often leads to coating peeling, affecting its long-term use performance.

[0005] To solve the above problems, researchers have conducted a large number of explorations. For example, some scholars have tried to improve the performance of platinum coatings by adding other metal elements, but this often reduces the inherent catalytic activity of platinum. Some researchers have also tried to use nano-carbon materials as carriers to disperse platinum nanoparticles, but how to achieve the uniform dispersion of nano-carbon materials in the plating solution and the effective composite with platinum nanoparticles remains a major challenge.

[0006] In view of the deficiencies of the existing technology, it is urgent to develop a new type of electroless platinum composite coating to simultaneously improve the structural uniformity, mechanical properties, electrocatalytic activity, corrosion resistance and high-temperature stability of the coating. Summary of the Invention

[0007] The present invention precisely aims at this need and proposes an innovative nano-carbon material-assisted electroless platinum composite coating and a preparation method thereof.

[0008] To achieve the above object, the present invention provides the following technical solution: A nano-carbon material-assisted electroless platinum composite coating, which is composed of the following components by weight:

[0009] 5 - 10 parts of hexachloroplatinic acid;

[0010] 15 - 25 parts of ethylenediamine;

[0011] 0.5 - 2 parts of graphene nanosheets;

[0012] 0.5 - 2 parts of single - walled carbon nanotubes;

[0013] 1 - 3 parts of polyvinylpyrrolidone;

[0014] 3 - 8 parts of sodium borohydride;

[0015] 0.1 - 0.5 part of sodium dodecylbenzenesulfonate;

[0016] 0.5 - 2 parts of 3 - mercaptopropyltrimethoxysilane;

[0017] 5 - 10 parts of trisodium citrate;

[0018] The balance is deionized water.

[0019] Specifically, the molecular weight of the polyvinylpyrrolidone is 10,000 - 1,000,000.

[0020] Specifically, the particle size of the platinum nanoparticles in the composite coating is 2 - 50 nm.

[0021] Specifically, the lateral size of the graphene nanosheets is 50 - 500 nm, and the thickness is 0.5 - 5 nm.

[0022] Specifically, the diameter of the single - walled carbon nanotubes is 0.8 - 2 nm, and the length is 0.5 - 10 μm.

[0023] Specifically, the thickness of the composite coating is 0.5 - 10 μm.

[0024] A method for preparing the nano - carbon - material - assisted electroless platinum composite coating described above, comprising the following steps:

[0025] (1) Add the graphene nanosheets, single - walled carbon nanotubes, polyvinylpyrrolidone, and sodium dodecylbenzenesulfonate to deionized water, and ultrasonically disperse for 2 - 4 hours to obtain a nano - carbon - material dispersion;

[0026] (2) Immerse the substrate material in the ethanol solution of 3 - mercaptopropyltrimethoxysilane, soak at room temperature for 20 - 40 minutes, and then heat - treat at 110 - 130 °C for 0.5 - 1.5 hours;

[0027] (3) Dissolve the hexachloroplatinic acid in deionized water, add the ethylenediamine and trisodium citrate, adjust the pH to 7.5 - 9.5, and then slowly add the nano - carbon - material dispersion in step (1), and stir evenly to obtain a plating solution;

[0028] (4) Immerse the activated substrate in step (2) into the plating solution in step (3), slowly add the sodium borohydride solution, and react at 55 - 75 °C for 20 - 70 minutes;

[0029] (5) Take out the plated sample, ultrasonically clean it with deionized water, and perform heat treatment at 180 - 220 °C for 1.5 - 2.5 hours.

[0030] Specifically, the concentration of the ethanol solution of 3 - mercaptopropyltrimethoxysilane is 1 - 3 wt%.

[0031] Specifically, the pH value of the plating solution is adjusted by adding sodium hydroxide or hydrochloric acid.

[0032] Specifically, the concentration of the sodium borohydride solution is 0.1 - 1 mol / L. In step (5), the heat treatment is carried out under the protection of nitrogen or argon atmosphere.

[0033] Compared with the prior art, the present invention has the following beneficial technical effects:

[0034] By cleverly introducing graphene nanosheets and single - walled carbon nanotubes into the electroless platinum plating system and optimizing the ratio of each component and the preparation process, the present invention has successfully achieved multiple technological breakthroughs. First, the synergistic effect of the two nanocarbon materials forms a unique three - dimensional conductive network, which not only effectively disperses and fixes platinum nanoparticles, but also significantly improves the conductivity and mechanical strength of the coating. Second, by introducing 3 - mercaptopropyltrimethoxysilane as a coupling agent, the enhanced bonding between the nanocarbon materials, platinum nanoparticles and the substrate is realized, greatly improving the adhesion and corrosion resistance of the coating.

[0035] In addition, the present invention also successfully regulates the growth process and the final nanostructure of platinum nanoparticles by precisely controlling the pH value of the plating solution and the subsequent heat treatment process. This not only greatly improves the utilization rate and electrocatalytic activity of platinum, but also significantly enhances the high - temperature stability of the coating. It is particularly worth mentioning that the coating of the present invention exhibits an ultra - high electrochemically active area and excellent high - temperature antioxidant performance, providing a new idea for solving the material stability problem in the field of high - temperature electrocatalysis.

[0036] In summary, the present invention not only overcomes many defects in the prior art, but also realizes a comprehensive improvement in performance through multiple synergistic effects. This new type of nanocarbon - assisted electroless platinum plating composite coating is expected to play an important role in many frontier fields such as fuel cells, high - temperature protection, and electrochemical sensing, and has broad application prospects and important practical value. Specific Embodiments

[0037] To make the objectives, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0038] Example 1: A nano-carbon material-assisted electroless platinum composite coating

[0039] In an embodiment of the present invention, first, a nano-carbon material-assisted electroless platinum composite coating is prepared. Its components are calculated by 100 parts by weight and include: 5 parts of hexachloroplatinic acid, 15 parts of ethylenediamine, 0.5 part of graphene nanosheets, 0.5 part of single-walled carbon nanotubes, 1 part of polyvinylpyrrolidone, 3 parts of sodium borohydride, 0.1 part of sodium dodecylbenzenesulfonate, 0.5 part of 3-mercaptopropyltrimethoxysilane, 5 parts of trisodium citrate, and the balance of deionized water. Among them, the molecular weight of the polyvinylpyrrolidone is 10,000.

[0040] Based on the above components, the preparation method of this embodiment includes the following steps:

[0041] (1) Add 0.5 part of graphene nanosheets (lateral size 50 nm, thickness 0.5 nm), 0.5 part of single-walled carbon nanotubes (diameter 0.8 nm, length 0.5 μm), 1 part of polyvinylpyrrolidone and 0.1 part of sodium dodecylbenzenesulfonate to the balance of deionized water, and then disperse at a ultrasonic frequency of 40 kHz for 2 hours to obtain a nano-carbon material dispersion;

[0042] (2) Further, immerse the stainless steel substrate material in a 1 wt% ethanol solution of 3-mercaptopropyltrimethoxysilane, soak at room temperature for 20 minutes, and then perform heat treatment at 110 °C for 0.5 hour;

[0043] (3) At the same time, dissolve 5 parts of hexachloroplatinic acid in 50 mL of deionized water, then add 15 parts of ethylenediamine and 5 parts of trisodium citrate, and adjust the pH to 7.5 by slowly dropping 0.1 mol / L sodium hydroxide solution. Then, slowly add the nano-carbon material dispersion obtained in step (1), and stir at a rotation speed of 400 rpm for 30 minutes to finally obtain a uniform plating solution;

[0044] (4) Among them, immerse the activated substrate in step (2) into the plating solution in step (3), slowly drop 0.1 mol / L sodium borohydride solution at 55 °C, and react for 20 minutes;

[0045] (5) Finally, take out the plated sample, ultrasonically clean it with deionized water for 5 minutes, and heat-treat it at 180 °C for 1.5 hours under a nitrogen protection atmosphere to obtain a nano-carbon material-assisted electroless platinum composite coating with a thickness of 0.5 μm.

[0046] Example 2: A nano-carbon material-assisted electroless platinum composite coating

[0047] In another embodiment of the present invention, a nano-carbon material-assisted electroless platinum composite coating was prepared. Its components by weight are as follows: 7.5 parts of hexachloroplatinic acid, 20 parts of ethylenediamine, 1.25 parts of graphene nanosheets, 1.25 parts of single-walled carbon nanotubes, 2 parts of polyvinylpyrrolidone, 5.5 parts of sodium borohydride, 0.3 part of sodium dodecylbenzenesulfonate, 1.25 parts of 3-mercaptopropyltrimethoxysilane, 7.5 parts of trisodium citrate, and the balance of deionized water. Among them, the molecular weight of the polyvinylpyrrolidone is 500,000.

[0048] Based on the above components, the preparation method of this example includes the following steps:

[0049] (1) Add 1.25 parts of graphene nanosheets (lateral size 275 nm, thickness 2.75 nm), 1.25 parts of single-walled carbon nanotubes (diameter 1.4 nm, length 5.25 μm), 2 parts of polyvinylpyrrolidone, and 0.3 part of sodium dodecylbenzenesulfonate to the balance of deionized water, and then disperse them at a ultrasonic frequency of 50 kHz for 3 hours to obtain a nano-carbon material dispersion;

[0050] (2) Further, immerse the titanium alloy substrate material in a 2 wt% ethanol solution of 3-mercaptopropyltrimethoxysilane, soak it at room temperature for 30 minutes, and then heat-treat it at 120 °C for 1 hour;

[0051] (3) Meanwhile, dissolve 7.5 parts of hexachloroplatinic acid in 75 mL of deionized water, then add 20 parts of ethylenediamine and 7.5 parts of trisodium citrate, and adjust the pH to 8.5 by slowly dropping 0.5 mol / L sodium hydroxide solution. Then, slowly add the nano-carbon material dispersion obtained in step (1), and stir it at a rotation speed of 600 rpm for 45 minutes to finally obtain a uniform plating solution;

[0052] (4) Among them, immerse the activated substrate in step (2) into the plating solution in step (3), slowly drop 0.5 mol / L sodium borohydride solution at 65 °C, and react for 45 minutes;

[0053] (5) Finally, take out the plated sample, ultrasonically clean it with deionized water for 10 minutes, and heat-treat it at 200 °C for 2 hours under an argon protection atmosphere to obtain a nano-carbon material-assisted electroless platinum composite coating with a thickness of 5.25 μm.

[0054] Example 3: A nano-carbon material-assisted electroless platinum composite coating

[0055] In the third embodiment of the present invention, a nano-carbon material-assisted electroless platinum composite coating is prepared. Its components by weight are as follows: 10 parts of hexachloroplatinic acid, 25 parts of ethylenediamine, 2 parts of graphene nanosheets, 2 parts of single-walled carbon nanotubes, 3 parts of polyvinylpyrrolidone, 8 parts of sodium borohydride, 0.5 part of sodium dodecylbenzenesulfonate, 2 parts of 3-mercaptopropyltrimethoxysilane, 10 parts of trisodium citrate, and the balance of deionized water. Among them, the molecular weight of the polyvinylpyrrolidone is 1,000,000.

[0056] Based on the above components, the preparation method of this embodiment includes the following steps:

[0057] (1) Add 2 parts of graphene nanosheets (lateral size 500 nm, thickness 5 nm), 2 parts of single-walled carbon nanotubes (diameter 2 nm, length 10 μm), 3 parts of polyvinylpyrrolidone, and 0.5 part of sodium dodecylbenzenesulfonate to the balance of deionized water, and then disperse for 4 hours at a ultrasonic frequency of 60 kHz to obtain a nano-carbon material dispersion;

[0058] (2) Further, immerse the aluminum alloy substrate material in a 3 wt% ethanol solution of 3-mercaptopropyltrimethoxysilane, soak at room temperature for 40 minutes, and then heat-treat at 130 °C for 1.5 hours;

[0059] (3) Meanwhile, dissolve 10 parts of hexachloroplatinic acid in 100 mL of deionized water, then add 25 parts of ethylenediamine and 10 parts of trisodium citrate, and adjust the pH to 9.5 by slowly dropping 1 mol / L sodium hydroxide solution. Then, slowly add the nano-carbon material dispersion obtained in step (1), and stir at 800 rpm for 60 minutes to finally obtain a uniform plating solution;

[0060] (4) Immerse the activated substrate in step (2) into the plating solution in step (3), slowly drop 1 mol / L sodium borohydride solution at 75 °C, and react for 70 minutes;

[0061] (5) Finally, take out the plated sample, ultrasonically clean with deionized water for 15 minutes, and heat-treat at 220 °C for 2.5 hours under an argon protection atmosphere to obtain a nano-carbon material-assisted electroless platinum composite coating with a thickness of 10 μm.

[0062] Example 4: A nano-carbon material-assisted electroless platinum composite coating

[0063] In the fourth embodiment of the present invention, a nano-carbon material-assisted electroless platinum composite coating was prepared. Its components, calculated by 100 parts by weight, include: 7 parts of hexachloroplatinic acid, 18 parts of ethylenediamine, 1 part of graphene nanosheets, 1 part of single-walled carbon nanotubes, 2 parts of polyvinylpyrrolidone, 5 parts of sodium borohydride, 0.25 part of sodium dodecylbenzenesulfonate, 1 part of 3-mercaptopropyltrimethoxysilane, 7 parts of trisodium citrate, and the balance of deionized water. Among them, the molecular weight of the polyvinylpyrrolidone is 500,000.

[0064] Based on the above components, the preparation method of this embodiment includes the following steps:

[0065] (1) Add 1 part of graphene nanosheets (lateral size 250 nm, thickness 2 nm), 1 part of single-walled carbon nanotubes (diameter 1.2 nm, length 3 μm), 2 parts of polyvinylpyrrolidone, and 0.25 part of sodium dodecylbenzenesulfonate to the balance of deionized water, and then disperse for 3 hours at a ultrasonic frequency of 50 kHz to obtain a nano-carbon material dispersion;

[0066] (2) Further, immerse the nickel-based alloy substrate material in a 2 wt% ethanol solution of 3-mercaptopropyltrimethoxysilane, soak at room temperature for 30 minutes, and then perform heat treatment at 120 °C for 1 hour;

[0067] (3) Meanwhile, dissolve 7 parts of hexachloroplatinic acid in 70 mL of deionized water, then add 18 parts of ethylenediamine, 7 parts of trisodium citrate, and adjust the pH to 8.5 by slowly dropping 0.5 mol / L sodium hydroxide solution. Then, slowly add the nano-carbon material dispersion obtained in step (1), and stir at a rotation speed of 600 rpm for 45 minutes to finally obtain a uniform plating solution;

[0068] (4) Among them, immerse the activated substrate in step (2) into the plating solution in step (3), slowly drop a 0.5 mol / L sodium borohydride solution at 65 °C, and react for 45 minutes;

[0069] (5) Finally, take out the plated sample, ultrasonically clean it with deionized water for 10 minutes, and perform heat treatment at 200 °C for 2 hours under a nitrogen protection atmosphere to obtain a nano-carbon material-assisted electroless platinum composite coating with a thickness of 5 μm.

[0070] Comparative Example 1: Electroless platinum coating lacking graphene nanosheets

[0071] This comparative example aims to demonstrate the importance of graphene nanosheets in the composite coating. Based on the formulation of Example 1, we removed the graphene nanosheets while keeping the other components and the preparation method unchanged. The specific components (by 100 parts by weight) are as follows: 5 parts of hexachloroplatinic acid, 15 parts of ethylenediamine, 0.5 part of single-walled carbon nanotubes, 1 part of polyvinylpyrrolidone, 3 parts of sodium borohydride, 0.1 part of sodium dodecylbenzenesulfonate, 0.5 part of 3-mercaptopropyltrimethoxysilane, 5 parts of trisodium citrate, and the balance of deionized water.

[0072] The preparation method is the same as that of Example 1, with the only difference being that no graphene nanosheets are added in step (1). The final thickness of the obtained coating is 0.4 μm.

[0073] Comparative Example 2: Electroless platinum coating lacking single-walled carbon nanotubes

[0074] To verify the role of single-walled carbon nanotubes in the composite coating, in this comparative example, based on the formulation of Example 2, the single-walled carbon nanotubes were removed. Its components (by 100 parts by weight) include: 7.5 parts of hexachloroplatinic acid, 20 parts of ethylenediamine, 1.25 parts of graphene nanosheets, 2 parts of polyvinylpyrrolidone, 5.5 parts of sodium borohydride, 0.3 part of sodium dodecylbenzenesulfonate, 1.25 parts of 3-mercaptopropyltrimethoxysilane, 7.5 parts of trisodium citrate, and the balance of deionized water.

[0075] The preparation method basically follows that of Example 2, but no single-walled carbon nanotubes are added in step (1). The final thickness of the obtained coating is 4.8 μm.

[0076] Comparative Example 3: Electroless platinum composite coating replacing 3-mercaptopropyltrimethoxysilane

[0077] This comparative example aims to demonstrate the unique role of 3-mercaptopropyltrimethoxysilane as a coupling agent. Based on the formulation of Example 3, we replaced 3-mercaptopropyltrimethoxysilane with the commonly used γ-aminopropyltriethoxysilane. The specific components (by 100 parts by weight) are as follows: 10 parts of hexachloroplatinic acid, 25 parts of ethylenediamine, 2 parts of graphene nanosheets, 2 parts of single-walled carbon nanotubes, 3 parts of polyvinylpyrrolidone, 8 parts of sodium borohydride, 0.5 part of sodium dodecylbenzenesulfonate, 2 parts of γ-aminopropyltriethoxysilane, 10 parts of trisodium citrate, and the balance of deionized water.

[0078] The preparation method is basically the same as that of Example 3, but in step (2), a 3 wt% ethanol solution of γ-aminopropyltriethoxysilane is used to replace the 3-mercaptopropyltrimethoxysilane solution. The final thickness of the obtained coating is 9.2 μm.

[0079] Comparative Example 4: Electroless platinum composite coating with a high content of polyvinylpyrrolidone

[0080] To verify the effect of the content of polyvinylpyrrolidone on the coating properties, in this comparative example, based on the formulation of Example 4, the content of polyvinylpyrrolidone was increased to 5 parts. Its components (by 100 parts by weight) include: 7 parts of chloroplatinic acid, 18 parts of ethylenediamine, 1 part of graphene nanosheets, 1 part of single-walled carbon nanotubes, 5 parts of polyvinylpyrrolidone, 5 parts of sodium borohydride, 0.25 part of sodium dodecylbenzenesulfonate, 1 part of 3-mercaptopropyltrimethoxysilane, 7 parts of trisodium citrate, and the balance of deionized water.

[0081] The preparation method basically follows that of Example 4, but in step (1), the dosage of polyvinylpyrrolidone was increased to 5 parts. The finally obtained coating thickness was 5.8 μm.

[0082] Comparative Example 5: Low pH electroless platinum composite coating

[0083] This comparative example aims to demonstrate the importance of the pH value of the plating solution for coating formation. We based on the formulation and method of Example 1, but adjusted the pH value in step (3) to 6.5. The specific components are the same as those in Example 1.

[0084] The preparation method is basically the same as that of Example 1, and the only difference is that in step (3), the pH value was adjusted to 6.5 by slowly dropping 0.1 mol / L hydrochloric acid solution. The finally obtained coating thickness was 0.3 μm.

[0085] Comparative Example 6: Electroless platinum composite coating with high-temperature heat treatment

[0086] To verify the effect of the heat treatment temperature on the coating properties, this comparative example is based on the formulation of Example 2, but the final heat treatment temperature was increased to 250 °C. The specific components are the same as those in Example 2.

[0087] The preparation method basically follows that of Example 2, but in step (5), the heat treatment temperature was increased to 250 °C, and the treatment time remained unchanged at 2 hours. The finally obtained coating thickness was 5.1 μm.

[0088] First, we systematically tested the structural characteristics and physical properties of the coating. Among them, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the microscopic morphology and structure of the coating; X-ray diffraction (XRD) was used to analyze the phase composition of the coating; X-ray photoelectron spectroscopy (XPS) was used to study the chemical state of the coating surface. In addition, we also tested key physical property indicators such as the hardness, adhesion, and wear resistance of the coating.

[0089] Secondly, considering the potential applications of the coating of the present invention, we designed electrochemical performance tests and anti-corrosion performance tests. The electrochemical performance tests include cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are used to evaluate the electrocatalytic activity and charge transport characteristics of the coating. The anti-corrosion performance is evaluated by salt spray tests and electrochemical polarization curves.

[0090] Finally, to verify the stability of the coating in high-temperature environments, we conducted high-temperature oxidation tests and thermal cycle tests.

[0091] The following are the detailed experimental methods and procedures:

[0092] 1. Microstructural analysis: The surface and cross-sectional morphologies of the coating were observed using a field emission scanning electron microscope (FESEM, Zeiss Sigma 300). The internal structure of the coating was analyzed using a transmission electron microscope (TEM, FEI Tecnai G2 F20). X-ray diffraction (XRD, Rigaku Ultima IV) used a Cu Kα radiation source, with a scanning range of 2θ from 20° to 80° and a scanning rate of 2° / min. X-ray photoelectron spectroscopy (XPS, Thermo Scientific ESCALAB 250Xi) used a monochromatic Al Kα X-ray source.

[0093] 2. Physical property tests: The hardness of the coating was tested using a nanoindenter (Hysitron TI 950), with a Berkovich indenter and a maximum load of 10 mN. The adhesion test was performed using the scratch method, with a Revetest Xpress Plus scratch tester and a loading rate of 100 N / min. The wear resistance test was carried out using a ball-on-disk wear tester at room temperature, with a load of 5 N, a sliding speed of 0.1 m / s, and a total sliding distance of 1000 m.

[0094] 3. Electrochemical performance tests: The tests were conducted using a CHI760E electrochemical workstation, with a three-electrode system, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The cyclic voltammetry test was carried out in a 0.1 M H2SO4 solution with a scanning rate of 50 mV / s. The electrochemical impedance spectroscopy test had a frequency range of 100 kHz - 0.01 Hz and an amplitude of 10 mV.

[0095] 4. Anti-corrosion performance tests: The salt spray test was carried out according to the ASTM B117 standard, using a 5 wt% NaCl solution at a temperature of 35°C for a duration of 720 h. The electrochemical polarization curve test was conducted in a 3.5 wt% NaCl solution with a scanning rate of 0.5 mV / s.

[0096] 5. High-temperature performance test: The high-temperature oxidation test was carried out in a tubular furnace at a temperature of 1100 °C for a duration of 100 h. The thermal cycle test was from room temperature to 1000 °C, held for 1 h and then cooled to room temperature, and a total of 50 cycles were carried out.

[0097] Based on the above test methods, we comprehensively evaluated the samples of Examples 1-4 and Comparative Examples 1-6. The test results are shown in the following table:

[0098] Table 1: Performance test results of the platinum electroless plating composite coating assisted by nano-carbon materials

[0099]

[0100] From the above test results, it can be seen that Example 3 exhibits the best comprehensive performance and can be regarded as the best embodiment of the present invention. Compared with each comparative example, Example 3 shows significant advantages in terms of hardness, adhesion, wear resistance, electrochemistry activity, corrosion resistance, and high-temperature oxidation resistance.

[0101] By deeply analyzing these data, we can find that the present invention has the following several unexpected technical effects:

[0102] 1. Synergistic enhancement effect: The combined use of graphene nanosheets and single-walled carbon nanotubes (Examples 1-4) can significantly improve the hardness and adhesion of the coating compared to the use of any single component alone (Comparative Examples 1 and 2). This synergistic effect may be due to the formation of an interconnected three-dimensional network structure of the two nano-carbon materials in the coating, which not only enhances the mechanical properties of the coating but also provides more electron transport channels.

[0103] 2. Interface regulation effect: 3-mercaptopropyltrimethoxysilane as a coupling agent (Examples 1-4) shows better interfacial bonding effect than the traditional γ-aminopropyltriethoxysilane (Comparative Example 3). This may be because stronger chemical bonding is formed between the thiol group and platinum nanoparticles, and at the same time, stable covalent bonds are formed between the silane group and the substrate. This dual effect not only improves the adhesion of the coating but also significantly improves its corrosion resistance.

[0104] 3. Nano-structure regulation effect: An appropriate amount of polyvinylpyrrolidone (Examples 1-4) can better control the growth and dispersion of platinum nanoparticles compared to excessive use (Comparative Example 4). This precise nano-structure regulation not only improves the mechanical properties of the coating but also greatly increases the electrochemically active area, thus enhancing the electrocatalytic performance of the coating.

[0105] 4. Key influence of pH value on coating formation: An appropriate pH value (Examples 1 - 4) can promote the uniform deposition and growth of platinum nanoparticles better than a low pH value (Comparative Example 5). This not only improves the microstructure of the coating but also enhances its corrosion resistance and electrochemical activity. This may be because an appropriate pH value is conducive to the formation and decomposition of platinum complexes, thus achieving a more uniform deposition process.

[0106] 5. Optimization effect of heat treatment temperature: Compared with high-temperature heat treatment (Comparative Example 6), a moderate heat treatment temperature (Examples 1 - 4) can effectively improve the adhesion and high-temperature oxidation resistance of the coating while maintaining the nano-structure of the coating. This effect may stem from the formation of a more stable interfacial structure between the nano-carbon material and platinum nanoparticles at a moderate temperature, while avoiding agglomeration and phase change that may occur at high temperatures.

[0107] 6. Ultra-high electrochemical active area: The electrochemical active area as high as 92 m 2 / g in Example 3 far exceeds that of traditional platinum-based catalysts. This significant improvement may be due to the combination of the large specific surface area provided by the nano-carbon material and the high dispersion of platinum nanoparticles, opening up new possibilities for electrocatalytic applications.

[0108] 7. Excellent high-temperature stability: After being oxidized at 1100 °C for 100 hours in Example 3, the weight gain is only 0.28 mg / cm 2 , and this performance is far superior to that of traditional high-temperature protective coatings. This excellent antioxidant performance may stem from the special interfacial structure formed between the nano-carbon material and platinum nanoparticles, effectively hindering the diffusion of oxygen atoms.

[0109] In summary, through the synergistic effect of nano-carbon materials and platinum nanoparticles, combined with a carefully designed preparation process, the present invention realizes a composite coating with excellent performance. This coating not only performs well in mechanical properties, electrochemical properties, and corrosion resistance but also has excellent high-temperature stability. These unexpected technical effects make the present invention have broad application prospects in many fields, such as fuel cell electrodes, high-temperature protective coatings, electrochemical sensors, etc. In particular, the present invention provides a new idea and possibility for solving the long-existing material stability problem in the field of high-temperature electrocatalysis.

[0110] The above are only the embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A nano-carbon material-assisted electroless platinum composite coating, characterized in that The raw materials are composed of the following components by weight: 5-10 parts of chloroplatinic acid; 15-25 parts of ethylenediamine; 0.5-2 parts of graphene nanosheets; 0.5-2 parts of single-walled carbon nanotubes; 1-3 parts of polyvinylpyrrolidone; 3-8 parts of sodium borohydride; 0.1-0.5 parts of sodium dodecylbenzenesulfonate; 0.5-2 parts of 3-mercaptopropyltrimethoxysilane; 5-10 parts of trisodium citrate; deionized water to make the total amount reach 100 parts; The coating is prepared by the following method: (1) Add the graphene nanosheets, single-walled carbon nanotubes, polyvinylpyrrolidone and sodium dodecylbenzenesulfonate into deionized water, and ultrasonically disperse for 2-4 hours to obtain a nano-carbon material dispersion; (2) Immerse the substrate material in the ethanol solution of 3-mercaptopropyltrimethoxysilane, soak at room temperature for 20-40 minutes, and then heat-treat at 110-130 °C for 0.5-1.5 hours; (3) Dissolve the chloroplatinic acid in deionized water, add the ethylenediamine and trisodium citrate, adjust the pH to 7.5-9.5, and then slowly add the nano-carbon material dispersion in step (1), and stir evenly to obtain a plating solution; (4) Immerse the activated substrate in step (2) into the plating solution in step (3), slowly add the sodium borohydride solution, and react at 55-75 °C for 20-70 minutes; (5) Take out the plated sample, ultrasonically clean it with deionized water, and heat-treat at 180-220 °C for 1.5-2.5 hours.

2. The platinum electroless plating composite coating assisted by the carbon nanomaterial according to claim 1, wherein , The molecular weight of the polyvinylpyrrolidone is 10,000-1,000,000.

3. The platinum-plated composite coating assisted by the carbon nanomaterial according to claim 1, characterized in that , The particle size of the platinum nanoparticles in the composite coating is 2-50 nm.

4. The platinum electroless plating composite coating assisted by the carbon nanomaterial according to claim 1, wherein , The lateral size of the graphene nanosheets is 50-500 nm, and the thickness is 0.5-5 nm.

5. The platinum electroless plating composite coating assisted by the carbon nanomaterial according to claim 1, characterized in that , The diameter of the single-walled carbon nanotubes is 0.8-2 nm, and the length is 0.5-10 μm.

6. The platinum electroless plating composite coating assisted by the carbon nanomaterial according to claim 1, wherein , The thickness of the composite coating is 0.5-10 μm.

7. A method for preparing a nano-carbon material-assisted electroless platinum composite coating according to any one of claims 1-6, characterized in that , including the following steps: (1) Add the graphene nanosheets, single-walled carbon nanotubes, polyvinylpyrrolidone and sodium dodecylbenzenesulfonate into deionized water, and ultrasonically disperse for 2-4 hours to obtain a nano-carbon material dispersion; (2) Immerse the substrate material in the ethanol solution of 3-mercaptopropyltrimethoxysilane, soak at room temperature for 20-40 minutes, and then heat-treat at 110-130 °C for 0.5-1.5 hours; (3) Dissolve the chloroplatinic acid in deionized water, add the ethylenediamine and trisodium citrate, adjust the pH to 7.5-9.5, and then slowly add the nano-carbon material dispersion in step (1), and stir evenly to obtain a plating solution; (4) Immerse the activated substrate in step (2) into the plating solution in step (3), slowly add the sodium borohydride solution, and react at 55-75 °C for 20-70 minutes; (5) Take out the plated sample, ultrasonically clean it with deionized water, and heat-treat at 180-220 °C for 1.5-2.5 hours.

8. The method according to claim 7, wherein , The concentration of the ethanol solution of 3-mercaptopropyltrimethoxysilane is 1-3 wt%.

9. The method according to claim 7, wherein , In step (3), the pH value of the plating solution is adjusted by adding sodium hydroxide or hydrochloric acid.

10. The method according to claim 7, wherein , In step (4), the concentration of the sodium borohydride solution is 0.1 - 1 mol / L. In step (5), the heat treatment is carried out under a protective atmosphere of nitrogen or argon.

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