Pt nanoparticle supported Fe-based MOF photocatalyst, and preparation method and application thereof

Abstract

The application discloses a kind of Pt nanoparticle load Fe-based MOF photocatalyst and its preparation method and application, belong to environmental energy technical field.The preparation method disclosed in the application uses 2-amino terephthalic acid, FeCl3·6H2O and aqueous solution of chloroplatinic acid hexahydrate as raw material, through hydrothermal reaction, Pt nanoparticle is dispersed in situ and loaded NH2-MIL-101 (Fe), reduces interface charge transfer resistance, inhibits the recombination of photo-generated carriers, to further improve the photocatalytic nitrogen fixation activity, using the synergistic effect of NH2-MIL-101 (Fe) composite photocatalyst containing Pt nanoparticle to achieve the purpose of improving the yield of photocatalytic conversion of nitrogen to ammonia, significantly solve the high energy consumption and environmental pollution problem of traditional industrial nitrogen fixation Haber-Bosch method.

Description

Technical Field

[0001] This invention belongs to the field of environmental energy technology, specifically relating to a Pt nanoparticle-supported Fe-based MOF photocatalyst, its preparation method, and its application. Background Technology

[0002] Ammonia is one of the world's most important chemical raw materials, playing an irreplaceable role in the synthesis of fertilizers, explosives, fibers, and plastics. Currently, global ammonia production mainly comes from the industrial synthesis process of the Haber-Bosch process. However, the Haber-Bosch process requires harsh reaction conditions, namely high temperature (450-550℃) and high pressure (15-25 MPa), using iron-based catalysts to synthesize NH3 from high-purity N2 and H2. This traditional process consumes approximately 2% of global energy annually and generates 20-30% of CO2 emissions from the chemical industry. Therefore, there is an urgent need to develop transformative green ammonia synthesis technologies.

[0003] Photocatalytic nitrogen fixation is considered a viable green technology to replace the traditional Haber-Bosch technique. Currently, several typical metal-based semiconductors (such as g-C3N4, TiO2, WO3, and Bi2MnO6) have been widely used in photocatalytic ammonia synthesis. However, traditional semiconductors often suffer from wide band gaps, rapid electron-hole recombination, slow charge transfer, low solar energy utilization, and limited exposure of active sites. Therefore, there is an urgent need to develop more efficient photocatalysts to meet the requirements of ammonia synthesis processes. Metal-organic frameworks (MOFs), with their porous structure, ultra-high specific surface area, and tunable molecular structure, are considered ideal photocatalysts for ammonia synthesis.

[0004] Although it is generally agreed that modifying MOFs with cocatalysts is one of the effective strategies to improve photocatalytic nitrogen fixation activity, promoting the interaction between MOFs and cocatalysts to achieve efficient charge transfer remains challenging. Summary of the Invention

[0005] The purpose of this invention is to provide a Pt nanoparticle-supported Fe-based MOF photocatalyst, its preparation method, and its application, in order to solve the problems of high energy consumption and environmental pollution associated with the traditional industrial nitrogen fixation Haber-Bosch method.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a method for preparing a Pt nanoparticle-supported Fe-based MOF photocatalyst, comprising the following steps:

[0008] 2-Aminoterephthalic acid and FeCl3·6H2O were added to a solvent and mixed to obtain a mixture;

[0009] After the mixture was subjected to a hydrothermal reaction, the resulting reaction precipitate was post-treated to obtain NH2-MIL-101(Fe) powder.

[0010] After mixing NH2-MIL-101(Fe) powder with water, a mixed solution was obtained. Then, an aqueous solution of chloroplatinic acid hexahydrate, a reducing agent, and a stabilizer were added dropwise to the mixed solution to obtain a Pt nanoparticle-supported Fe-based MOF photocatalyst.

[0011] Further, the ratio of the amount of 2-aminoterephthalic acid, FeCl3·6H2O and solvent is (54.3~55.0)mg:(162~162.5)mg:(30~31)mL.

[0012] Furthermore, the solvent is DMF.

[0013] Furthermore, the hydrothermal reaction is carried out at a temperature of 110°C for a duration of 48 hours.

[0014] Furthermore, the post-processing involves sequentially performing cooling, filtration, washing, and freeze-drying; the freeze-drying process takes 6–7 hours.

[0015] Furthermore, the ratio of NH2-MIL-101(Fe) powder to water is (133-135) mg: (20-22) mL.

[0016] Furthermore, the reducing agent is an aqueous solution of sodium borohydride; the stabilizer is citric acid.

[0017] Further, the ratio of the aqueous solution of chloroplatinic acid hexahydrate to the mixed solution is (0.1-0.7) mL: (20-22) mL; the ratio of the reducing agent, stabilizer, and mixed solution is 1.5 mL: 5 mg: (20-22) mL;

[0018] The concentration of the aqueous solution of chloroplatinic acid hexahydrate is 10–10.5 mg / mL.

[0019] The present invention also discloses a Pt nanoparticle-supported Fe-based MOF photocatalyst prepared by the above preparation method.

[0020] This invention also discloses the application of the above-mentioned Pt nanoparticle-supported Fe-based MOF photocatalyst in the photocatalytic conversion of nitrogen into ammonia.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention discloses a method for preparing a Pt nanoparticle-supported Fe-based MOF photocatalyst. Using 2-aminoterephthalic acid, FeCl3·6H2O, and an aqueous solution of chloroplatinic acid hexahydrate as raw materials, Pt nanoparticles are in-situ dispersed and supported on NH2-MIL-101(Fe) via a hydrothermal reaction. This reduces interfacial charge transfer resistance and inhibits the recombination of photogenerated carriers, thereby further enhancing the photocatalytic nitrogen fixation activity. The synergistic effect of the Pt nanoparticle-containing NH2-MIL-101(Fe) composite photocatalyst is utilized to increase the yield of ammonia synthesized from nitrogen through photocatalytic conversion, significantly solving the high energy consumption and environmental pollution problems of the traditional industrial Haber-Bosch nitrogen fixation method.

[0023] This invention also discloses a Pt nanoparticle-supported Fe-based MOF photocatalyst prepared by the above-described method. The catalyst is NH₂-MIL-101(Fe) supported on Pt nanoparticles. The Pt nanoparticles are in-situ dispersed. A directional electron transport channel is precisely constructed by bridging the Pt nanoparticles to the metal-organic framework (MOF) using a ligand with an -NH₂ group (NH₂-BDC). This effectively reduces interfacial charge transfer resistance, inhibits the recombination of photogenerated carriers, and thus enhances the adsorption and activation of N₂ molecules.

[0024] The present invention also discloses the application of the above-mentioned Pt nanoparticle-supported Fe-based MOF photocatalyst in the photocatalytic conversion of nitrogen gas to ammonia. According to relevant experimental results, compared with the unmodified NH2-MIL-101(Fe) material, the nitrogen fixation activity of the Pt@NM-101(Fe) composite photocatalyst of the present invention is significantly improved, and its ammonia production is increased by about 4.2 times. Attached Figure Description

[0025] Figure 1 The X-ray diffraction (XRD) patterns of Pt nanoparticle-supported Fe-based MOF photocatalysts and pure NH2-MIL-101(Fe) prepared in Examples 1 to 5 of this invention are shown.

[0026] Figure 2 This is a SEM image of the Pt nanoparticle-supported Fe-based MOF photocatalyst prepared in Example 4 of this invention.

[0027] Figure 3 This is a TEM image of the Pt nanoparticle-supported Fe-based MOF photocatalyst prepared in Example 4 of this invention.

[0028] Figure 4 This is a high-resolution TEM image of the Pt nanoparticle-supported Fe-based MOF photocatalyst prepared in Example 4 of this invention.

[0029] Figure 5The UV-Vis absorption spectra of the Pt nanoparticle-supported Fe-based MOF photocatalyst prepared in Example 4 of this invention and pure NH2-MIL-101(Fe) are shown.

[0030] Figure 6 The transient photocurrent response diagrams of the Pt nanoparticle-supported Fe-based MOF photocatalyst prepared in Example 4 of this invention and pure NH2-MIL-101(Fe) are shown.

[0031] Figure 7 Impedance diagrams of Pt nanoparticle-supported Fe-based MOF photocatalyst and pure NH2-MIL-101(Fe) prepared in Example 4 of this invention;

[0032] Figure 8 The images show the photocatalytic conversion of nitrogen to ammonia by Pt nanoparticle-supported Fe-based MOF photocatalysts prepared in Examples 1 to 5 of this invention, as well as the photocatalytic conversion of nitrogen to ammonia by pure NH2-MIL-101(Fe). Detailed Implementation

[0033] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0034] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0035] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0036] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0037] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0038] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0039] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0040] Example 1

[0041] A method for preparing a Pt nanoparticle-supported Fe-based MOF photocatalyst includes the following steps:

[0042] Weigh 54.3 mg of 2-aminoterephthalic acid and 162 mg of FeCl3·6H2O and add them to 30 mL of DMF. Stir for 30 minutes to obtain a mixture. Place the mixture in a polytetrafluoroethylene liner (50 mL) and hydrothermally heat at 110 °C for 48 hours to obtain a reaction precipitate. After cooling the reaction precipitate to room temperature, separate it from the reaction mixture by suction filtration and thoroughly wash it with DMF, ethanol and water to remove any unreacted raw materials. Finally, dry the obtained solid in a freeze dryer for 6 hours to obtain NH2-MIL-101(Fe) powder.

[0043] 0.133 g of NH2-MIL-101(Fe) powder was added to 20 mL of deionized water to form a mixed solution. 100 μL of 10 mg / mL H2PtCl6·6H2O aqueous solution was added to the mixed solution. After stirring evenly, 1.5 mL of 0.1 mol / L NaBH4 aqueous solution was added dropwise as a reducing agent and 5 mg of citric acid as a stabilizer. Finally, Pt nanoparticle-supported Fe-based MOF photocatalyst was obtained.

[0044] Example 2

[0045] A method for preparing a Pt nanoparticle-supported Fe-based MOF photocatalyst includes the following steps:

[0046] Weigh 54.3 mg of 2-aminoterephthalic acid and 162 mg of FeCl3·6H2O and add them to 30 ml of DMF. Stir for 30 minutes to obtain a mixture. Place the mixture in a polytetrafluoroethylene liner (50 mL) and hydrothermally heat at 110 °C for 48 hours to obtain a reaction precipitate. After cooling the reaction precipitate to room temperature, separate it from the reaction mixture by suction filtration and thoroughly wash it with DMF, ethanol and water to remove any unreacted raw materials. Finally, dry the obtained solid in a freeze dryer for 6 hours to obtain NH2-MIL-101(Fe) powder.

[0047] 0.133 g of NH2-MIL-101(Fe) powder was added to 20 mL of deionized water to form a mixed solution. 300 μL of 10 mg / mL H2PtCl6·6H2O aqueous solution was added to the mixed solution. After stirring evenly, 1.5 mL of 0.1 mol / L NaBH4 aqueous solution was added dropwise as a reducing agent and 5 mg of citric acid as a stabilizer. Finally, Pt nanoparticle-supported Fe-based MOF photocatalyst was obtained.

[0048] Example 3

[0049] A method for preparing a Pt nanoparticle-supported Fe-based MOF photocatalyst includes the following steps:

[0050] Weigh 54.3 mg of 2-aminoterephthalic acid and 162 mg of FeCl3·6H2O and add them to 30 ml of DMF. Stir for 30 minutes to obtain a mixture. Place the mixture in a polytetrafluoroethylene liner (50 mL) and hydrothermally heat at 110 °C for 48 hours to obtain a reaction precipitate. After cooling the reaction precipitate to room temperature, separate it from the reaction mixture by suction filtration and thoroughly wash it with DMF, ethanol and water to remove any unreacted raw materials. Finally, dry the obtained solid in a freeze dryer for 6 hours to obtain NH2-MIL-101(Fe) powder.

[0051] 0.133 g of NH2-MIL-101(Fe) powder was added to 20 mL of deionized water to form a mixed solution. 500 μL of 10 mg / mL H2PtCl6·6H2O aqueous solution was added to the mixed solution. After stirring evenly, 1.5 mL of 0.1 mol / L NaBH4 aqueous solution was added dropwise as a reducing agent and 5 mg of citric acid as a stabilizer. Finally, Pt nanoparticle-supported Fe-based MOF photocatalyst was obtained.

[0052] Example 4

[0053] A method for preparing a Pt nanoparticle-supported Fe-based MOF photocatalyst includes the following steps:

[0054] Weigh 54.3 mg of 2-aminoterephthalic acid and 162 mg of FeCl3·6H2O and add them to 30 ml of DMF. Stir for 30 minutes to obtain a mixture. Place the mixture in a polytetrafluoroethylene liner (50 mL) and hydrothermally heat at 110 °C for 48 hours to obtain a reaction precipitate. After cooling the reaction precipitate to room temperature, separate it from the reaction mixture by suction filtration and thoroughly wash it with DMF, ethanol and water to remove any unreacted raw materials. Finally, dry the obtained solid in a freeze dryer for 6 hours to obtain NH2-MIL-101(Fe) powder.

[0055] 0.133 g of NH2-MIL-101(Fe) powder was added to 20 mL of deionized water to form a mixed solution. 700 μL of 10 mg / mL H2PtCl6·6H2O aqueous solution was added to the mixed solution. After stirring evenly, 1.5 mL of 0.1 mol / L NaBH4 aqueous solution was added dropwise as a reducing agent and 5 mg of citric acid as a stabilizer to finally obtain the Fe-based MOF photocatalyst supported on Pt nanoparticles.

[0056] Example 5

[0057] A method for preparing a Pt nanoparticle-supported Fe-based MOF photocatalyst includes the following steps:

[0058] Weigh 54.3 mg of 2-aminoterephthalic acid and 162 mg of FeCl3·6H2O and add them to 30 ml of DMF. Stir for 30 minutes to obtain a mixture. Place the mixture in a polytetrafluoroethylene liner (50 mL) and hydrothermally heat at 110 °C for 48 hours to obtain a reaction precipitate. After cooling the reaction precipitate to room temperature, separate it from the reaction mixture by suction filtration and thoroughly wash it with DMF, ethanol and water to remove any unreacted raw materials. Finally, dry the obtained solid in a freeze dryer for 6 hours to obtain NH2-MIL-101(Fe) powder.

[0059] 0.133 g of NH2-MIL-101(Fe) powder was added to 20 mL of deionized water to form a mixed solution. 900 μL of 10 mg / mL H2PtCl6·6H2O aqueous solution was added to the mixed solution. After stirring evenly, 1.5 mL of 0.1 mol / L NaBH4 aqueous solution was added dropwise as a reducing agent and 5 mg of citric acid as a stabilizer. Finally, Pt nanoparticle-supported Fe-based MOF photocatalyst was obtained.

[0060] Example 6

[0061] A method for preparing a Pt nanoparticle-supported Fe-based MOF photocatalyst includes the following steps:

[0062] Weigh 54.3 mg of 2-aminoterephthalic acid and 162 mg of FeCl3·6H2O and add them to 30 mL of DMF. Stir for 30 minutes to obtain a mixture. Place the mixture in a 50 mL PTFE liner and hydrothermally heat at 110 °C for 48 hours to obtain a reaction precipitate. After cooling the reaction precipitate to room temperature, separate it from the reaction mixture by suction filtration and thoroughly wash it with DMF, ethanol and water to remove any unreacted raw materials. Finally, dry the obtained solid in a freeze dryer for 6 hours to obtain NH2-MIL-101(Fe) powder.

[0063] Example 7

[0064] A method for preparing a Pt nanoparticle-supported Fe-based MOF photocatalyst includes the following steps:

[0065] Weigh 55 mg of 2-aminoterephthalic acid and 162 mg of FeCl3·6H2O and add them to 30 mL of DMF. Stir for 30 minutes to obtain a mixture. Place the mixture in a polytetrafluoroethylene liner (50 mL) and hydrothermally heat at 110 °C for 48 hours to obtain a reaction precipitate. After cooling the reaction precipitate to room temperature, separate it from the reaction mixture by suction filtration and thoroughly wash it with DMF, ethanol and water to remove any unreacted raw materials. Finally, dry the obtained solid in a freeze dryer for 7 hours to obtain NH2-MIL-101(Fe) powder.

[0066] 0.135 g of the prepared NH2-MIL-101(Fe) powder was added to 22 mL of deionized water to form a mixed solution. 100 μL of 10 mg / mL H2PtCl6·6H2O aqueous solution was added to the prepared mixed solution. After stirring evenly, 1.5 mL of 0.1 mol / L NaBH4 aqueous solution was added dropwise as a reducing agent and 5 mg of citric acid as a stabilizer. Finally, Pt nanoparticle-supported Fe-based MOF photocatalyst was obtained.

[0067] Take 100 mg of the samples prepared in Examples 1 to 6 and perform X-ray diffraction tests, such as... Figure 1 As shown, the XRD pattern of the composite material is consistent with the main peak of the simulated NH2-MIL-101(Fe) phase, which proves the successful synthesis of the composite material.

[0068] Take 30 mg of the sample obtained in Example 4 and perform SEM testing. Figure 2 As shown, it exhibits a regular and slightly rough octahedral morphology with an average diameter of approximately 500 nm.

[0069] Take 30 mg of the sample prepared in Example 4 and perform TEM testing. Figure 3 As shown, it exhibits a regular octahedral morphology with an average diameter of approximately 500 nm.

[0070] Take 30 mg of the sample prepared in Example 4 and perform high-resolution TEM testing. Figure 4 As shown, its surface is loaded with Pt nanoparticles with a lattice spacing of about 0.22 nm, which belong to the (111) crystal plane of the Pt nanoparticles.

[0071] Take 50 mg of the sample obtained in Example 4 and an equal amount of NH2-MIL-101(Fe), and perform UV-Vis overabsorption spectroscopy. Figure 5 As shown, the light absorption of the composite photocatalyst Pt@NM-101(Fe) in the 200–800 nm range is further enhanced by in-situ loading of Pt nanoparticles. This is because when Pt metal nanoparticles interact with light, the electric field of the light polarizes the charge distribution, causing the charge to accumulate on the particle surface, thereby forming a local electric field on the surface, which further promotes light absorption and thus improves the efficiency of photocatalytic conversion of nitrogen into ammonia.

[0072] Ten mg of samples prepared in Examples 4 and 6 were used for transient photocurrent response spectrum testing. Figure 6 As shown, Pt@NM-101(Fe)-4 has a stronger photocurrent density, indicating that Pt@NM-101(Fe)-4 has a stronger charge migration rate.

[0073] Ten mg of samples prepared in Examples 4 and 6 were used for transient photocurrent response spectrum testing. Figure 7 As shown, Pt@NM-101(Fe)-4 has a lower interfacial charge transfer resistance, indicating that Pt@NM-101(Fe)-4 has a stronger charge migration rate.

[0074] Photocatalytic ammonia synthesis activity testing procedure: 30 mg of samples from Examples 1 to 6 were weighed out, and six experiments were set up. Each of the six samples was dispersed in a quartz photocatalytic reactor containing 100 mL of deionized water and connected to a circulating water cooling system, maintaining a controlled temperature of 25°C. The light source was a 300 W xenon lamp (282 mW·cm⁻¹). -2 First, the dispersion was incubated in the dark with high-purity N2 (80 mL·min⁻¹). -1 After bubbling and magnetic stirring for 30 minutes, the N2 in the solution was saturated, thus removing oxygen from the reactor. Subsequently, the xenon lamp was turned on, and 1 mL of the dispersion was taken every 60 minutes. The photocatalyst was separated by centrifugation at 5000 rpm to obtain a supernatant. The concentration of NH3 in the supernatant was determined by Nessler's reagent spectrophotometry, yielding the following results: Figure 8The curve shown. From Figure 8 It can be seen that, compared with unmodified NH2-MIL-101(Fe), the samples in Examples 1-5 showed significantly improved efficiency in the photocatalytic conversion of nitrogen into ammonia. + The yield was significantly increased, with Example 4 being the best, showing a 4.2-fold increase in activity.

[0075] Using NH2-MIL-101(Fe) as a support, this material exhibits excellent light absorption and photosensitivity, effectively absorbing solar energy and converting it into photogenerated carriers. Furthermore, Pt nanoparticles are in-situ dispersed and loaded onto NH2-MIL-101(Fe), and directional electron transport channels are precisely constructed by bridging the Pt nanoparticles to the metal-organic framework (MOF) using ligands with -NH2 groups (NH2-BDC). This effectively reduces interfacial charge transfer resistance, inhibits the recombination of photogenerated carriers, and thus enhances the adsorption and activation of N2 molecules. Utilizing the synergistic effect of the Pt nanoparticle-containing NH2-MIL-101(Fe) composite photocatalyst, the yield of ammonia synthesized from nitrogen through photocatalytic conversion is increased, significantly solving the high energy consumption and environmental pollution problems of traditional industrial nitrogen fixation. This method is simple to prepare, low in cost, and uses readily available raw materials.

[0076] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. The application of a Pt nanoparticle-supported Fe-based MOF photocatalyst in the photocatalytic conversion of nitrogen to ammonia, characterized in that, The preparation method of the photocatalyst includes the following steps: 2-Aminoterephthalic acid and FeCl3·6H2O were added to a solvent and mixed to obtain a mixture; After the mixture was subjected to a hydrothermal reaction, the resulting reaction precipitate was post-treated to obtain NH2-MIL-101-Fe powder. After mixing NH2-MIL-101-Fe powder with water, a mixed solution was obtained. Then, an aqueous solution of chloroplatinic acid hexahydrate, a reducing agent, and a stabilizer were added dropwise to the mixed solution to obtain a Pt nanoparticle-supported Fe-based MOF photocatalyst. The ratio of 2-aminoterephthalic acid, FeCl3·6H2O and solvent is (54.3~55.0) mg : (162~162.5) mg : (30~31) mL; The hydrothermal reaction was carried out at a temperature of 110°C for 48 hours.

2. The application according to claim 1, characterized in that, The solvent is DMF.

3. The application according to claim 1, characterized in that, The post-processing involves sequentially cooling, filtration, washing, and freeze-drying; the freeze-drying process takes 6-7 hours.

4. The application according to claim 1, characterized in that, The ratio of NH2-MIL-101-Fe powder to water is (133~135) mg: (20~22) mL.

5. The application according to claim 1, characterized in that, The reducing agent is an aqueous solution of sodium borohydride; the stabilizer is citric acid.

6. The application according to claim 1, characterized in that, The volume ratio of the aqueous solution of chloroplatinic acid hexahydrate to the mixed solution is (0.1~0.7) mL : (20~22) mL; the volume ratio of the reducing agent, stabilizer and mixed solution is 1.5 mL : 5 mg : (20~22) mL; The concentration of the aqueous solution of chloroplatinic acid hexahydrate is 10~10.5 mg / mL.

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