Simple wet chemical method for growing superfine platinum super-long nanowire in solution phase and application
By controlling the concentration of ligands and seeds in the solution phase using a wet chemical method, ultralong platinum nanowires were successfully synthesized, solving the complexity and template removal problems of traditional methods. This achieved efficient nanowire synthesis and expanded its application in electrocatalysis and optoelectronic devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-22
- Publication Date
- 2026-03-17
AI Technical Summary
Existing technologies make it difficult to synthesize high-quality platinum nanowires, especially ultralong nanowires, under simple conditions in a solution phase. Furthermore, traditional methods suffer from problems such as template removal affecting morphology and strict reaction conditions.
A wet chemical method was used to grow platinum nanowires in solution by controlling the concentration of ligands and seeds. The substrate was treated with APTES to control the density of the nanowires, which were then directly attached to the conductive substrate. Chloroplatinic acid, 4-mercaptobenzoic acid and sodium borohydride were used as the growth solution components, and the reaction time was controlled within 1-60 minutes.
This method enables the direct synthesis of ultralong nanowires, up to 1 μm in length, in solution, overcoming the complexity limitations of traditional methods. It offers potential applications in electrocatalysis, organic catalysis, and optoelectronic devices, while reducing operational risks and costs.
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Figure CN121669918A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanomaterial synthesis and relates to a method for synthesizing nanowires in a solution phase via a simple wet chemical process. Background Technology
[0002] One-dimensional platinum-based nanomaterials, due to their unique structure and properties, have shown broad application potential in various fields such as catalysis, energy, electronics, and biomedicine, including advantages such as high aspect ratio, large specific surface area, and rapid electron transport. However, this one-dimensional morphology makes the synthesis of platinum nanowires quite challenging. This is because metallic platinum crystals typically exhibit anisotropic growth characteristics. Therefore, current methods for synthesizing platinum ultrafine nanowires in solution are mainly based on hydrothermal methods, which control the longitudinal growth of nanowires through high-temperature and high-pressure reaction conditions and ligand assistance within the system. However, due to the strict limitations of the reaction conditions, the length of nanowires synthesized by this method is usually around 100 nm, which seriously affects their application in the catalysis field. In addition, it is difficult to find suitable templates with pore channels of the required diameter and length, and to completely remove the template without affecting the integrity of the nanowires, thus limiting the catalytic properties of platinum nanowires.
[0003] Furthermore, due to the differences in surface energy of different crystal planes, the directional differences in atomic deposition and diffusion kinetics, and the anisotropy of growth of Pt, unlike other noble metals such as Au and Ag, the surface energy difference of different crystal planes of Pt is relatively large. Therefore, it is difficult for platinum to undergo one-dimensional growth without the assistance of templates or ligands, and it is difficult to achieve morphological transformation by fine-tuning reaction parameters. In addition, Pt has high ionization energy and strong metal-oxygen bonding, making it difficult to be reduced. Therefore, the growth of platinum nanowires has strict requirements on reaction conditions and methods.
[0004] Therefore, considering the limitations of reaction conditions on the synthesis of platinum nanowires, various chemical methods have been developed for synthesis. However, due to the anisotropy of Pt metal growth and its difficult-to-reduce nature, the synthesis of high-quality platinum nanowires in solution under simple reaction conditions remains a huge challenge. Summary of the Invention
[0005] The purpose of this invention is to provide a simple wet chemical method for growing ultrafine platinum nanowires in a solution phase. This invention utilizes a wet chemical method, where platinum nanowires with varying surface roughness can be obtained by controlling the concentration of ligands under the influence of the growth solution. The density of the platinum nanowires can be controlled by altering the concentrations of APTES and the seed concentration. Furthermore, nanowires with good dispersibility can be directly attached to conductive substrates, allowing one-dimensional platinum nanowires to be used directly as working electrodes, providing significant application potential in fields such as electrocatalysis. This invention features a simple process, mild reaction conditions, low cost, and the advantages of precise controllability, ease of operation, and environmental friendliness in the synthesis of nanomaterials using wet chemical methods. This invention enables the direct synthesis of ultralong nanowires in a solution phase, with lengths reaching approximately 1 μm, a length currently unattainable by wet chemical methods. This technology overcomes the limitations of complex operations in traditional hydrothermal synthesis methods and solves the problem of nanowire morphology alteration caused by template removal, demonstrating enormous application prospects in electrocatalysis, organic catalysis, and optoelectronic devices.
[0006] To address the technical problem of this invention, the proposed technical solution is as follows: a simple wet chemical method for growing ultrafine platinum ultralong nanowires in solution phase, comprising the following steps:
[0007] (1) First, the silica substrate was hydrophilically treated by amylating it with triaminopropyltriethoxysilane solution (APTES) under acidic conditions.
[0008] (2) Take out the silica from step (1) and centrifuge it to wash away the excess APTES solution. Then add 150 μL of water, 150 μL of ethanol and 300 μL of acetic acid solution that does not contain APTES to ensure that the solution volume and pH conditions in the system remain unchanged. Add 100 μL of 3~5 nm platinum particle solution diluted 10 times with water and soak for 2 h.
[0009] (3) Take out the substrate from step (2) and centrifuge to wash away the excess platinum particle solution. In order to ensure that the overall volume and pH of the solution remain unchanged, 700 μL of the original solution needs to be added, including 250 μL of water, 150 μL of ethanol and 300 μL of acetic acid. Then prepare the growth solution.
[0010] (4) The main components of the growth solution are chloroplatinic acid, 4-mercaptobenzoic acid, and sodium borohydride; the growth solution is composed of water and ethanol, in which chloroplatinic acid is used as a metal precursor, 4-mercaptobenzoic acid is used as a ligand, and sodium borohydride is used as a reducing agent.
[0011] (5) In the wet chemical synthesis method, the growth solution consisting of ligand solution, precursor solution and reducing agent solution is added in sequence. After the reaction time is 1 min-60 min, the product is collected by centrifugation, rinsed once with water and ethanol, and dried before characterization.
[0012] Preferably, it includes the following steps:
[0013] (1) First, the silica substrate was hydrophilically treated by amylating it with triaminopropyltriethoxysilane solution (APTES) under acidic conditions.
[0014] (2) Centrifuge the silica substrate from step (1), remove the supernatant, wash away excess APTES solution, and immerse it in a solution of 3-5 nm platinum particles.
[0015] (3) Centrifuge the silica substrate from step (2), remove the supernatant, wash away the excess platinum particle solution, and then prepare the growth solution;
[0016] (4) The main components of the growth solution are chloroplatinic acid, 4-mercaptobenzoic acid, and sodium borohydride; the growth solution is composed of water and ethanol, wherein chloroplatinic acid serves as a metal precursor, 4-mercaptobenzoic acid ligand, and sodium borohydride serves as a reducing agent; the total volume of the growth solution is 300 μL.
[0017] (5) In the wet chemical synthesis method, the ligand solution, precursor solution and reducing agent solution are added in sequence. After the reaction time is 1 hour, the product is collected by centrifugation, washed once with water and ethanol, and dried before characterization.
[0018] Preferably, in step (1), the concentration of triaminopropyltriethoxysilane is 5 mM.
[0019] Preferably, the substrate is a 60nm silica.
[0020] Preferably, in step (1), the silane coupling agent used for functionalizing the substrate is triaminopropyltriethoxysilane (APTES) dissolved in a 1:1 solution of water and ethanol.
[0021] Preferably, in step (1), the acid used to treat the silica substrate is acetic acid.
[0022] Preferably, in step (4), the total volume of the reaction condition solution is 0.92 mL, the volume ratio of water to ethanol is close to 1:1, the concentration of chloroplatinic acid is 10.81 mM as a metal precursor, dissolved in a 1:1 solution of water and ethanol, the concentration of 4-mercaptobenzoic acid is 1 mM as a ligand, and the concentration of sodium borohydride is 34.21 mM as a reducing agent, dissolved in ice water.
[0023] Preferably, the steps include:
[0024] (1) First, the silica substrate was amination treatment for 20 min under acidic conditions using triaminopropyltriethoxysilane solution APTES. The concentration of triaminopropyltriethoxysilane was 5 mM. APTES was dissolved in equal volumes of ethanol and water at a ratio of 1:1. Ethanol was added first and then water was added during preparation to prevent excessive hydrolysis of the silane coupling agent. After the APTES was prepared, it was mixed with equal volumes of 17.4 M acetic acid to treat the silica substrate.
[0025] (2) Take out the silica from step (1) and centrifuge it to wash away the excess APTES solution. Then add 150 μL of water, 150 μL of ethanol and 300 μL of acetic acid solution that does not contain APTES to ensure that the solution volume and pH conditions in the system remain unchanged. Add 100 μL of 3~5 nm platinum particle solution diluted 10 times with water and soak for 2 h.
[0026] (3) Take out the substrate from step (2) and centrifuge to wash away the excess platinum particle solution. In order to ensure that the overall volume and pH of the solution remain unchanged, 700 μL of the original solution needs to be added, including 250 μL of water, 150 μL of ethanol and 300 μL of acetic acid. Then prepare the growth solution.
[0027] (4) The main components of the growth solution are chloroplatinic acid, 4-mercaptobenzoic acid, and sodium borohydride. The growth solution is composed of water and ethanol, with chloroplatinic acid as the metal precursor, 4-mercaptobenzoic acid as the ligand, and sodium borohydride as the reducing agent. The volume of the growth solution is 300 μL. The concentration of chloroplatinic acid is 10.81 mM as the metal precursor, dissolved in a 1:1 solution of water and ethanol. The concentration of 4-mercaptobenzoic acid is 1 mM as the ligand, and the concentration of sodium borohydride is 34.21 mM as the reducing agent, dissolved in ice water. 100 μL of each of the precursor, ligand, and reducing agent are added.
[0028] (5) The synthesis was carried out using a wet chemical method with a reaction time of 60 min. After the reaction was completed, the product was washed with ethanol and water, collected by centrifugation, and dried before characterization. The blackening of the reaction solution indicated that the platinum nanowire array was successfully synthesized.
[0029] To address the technical problem of this invention, another technical solution is proposed: ultra-long platinum ultrafine nanowires can be used in fuel cells or electrochemical catalysis.
[0030] Beneficial effects:
[0031] Compared with existing technologies, this invention can directly synthesize ultralong nanowires in the solution phase, with the longest reaching about 1 μm, which is a length that cannot be achieved by current wet chemical methods. This technology breaks through the limitation of complex operation of traditional hydrothermal synthesis methods and solves the problem of changes in nanowire morphology caused by template removal. It shows great application prospects in fields such as electrocatalysis, organic catalysis and optoelectronic devices.
[0032] The platinum nanowires prepared by this invention, due to their unique structural characteristics, possess a one-dimensional linear structure suitable for use in fuel cells such as ethanol fuel cells and proton exchange membrane batteries, exhibiting excellent electrocatalytic activity. Furthermore, compared to experiments on macroscopic substrates, this invention enables the direct generation of well-dispersed nanowires in the solution phase, avoiding the aggregation of nanowires caused by ultrasonication of the substrate.
[0033] This method is simple to operate and significantly reduces the risks associated with traditional, complex methods for synthesizing platinum nanowires. Furthermore, the density of the platinum nanowires can be controlled by altering the concentrations of the silane coupling agent and the added seeds. This offers great application potential for fields such as electrocatalysis. The invention features a simple process, mild reaction conditions, low cost, and the wet chemical method for synthesizing nanomaterials offers advantages such as ease of operation and environmental friendliness.
[0034] The surface treatment of the substrate in this technology is quite sensitive because, compared to the macroscopic stability of the substrate, the silica surface in the solution phase is richer in silanol groups. Therefore, there are strict requirements on the number of amino groups on the substrate surface, and acid must be added during the amination treatment. Figure 1 As shown, the addition of acid promotes the hydrolysis of APTES and inhibits its self-condensation, thereby reducing the number of surface amino groups. This is necessary to obtain nanowires with good dispersibility and no nucleation phenomenon. In addition, the type and concentration of ligands and reducing agents need to be controlled.
[0035] In step (2), changing the concentration of the soaked seeds can yield platinum nanowires with different densities.
[0036] At a chloroplatinic acid concentration of 10.81 mM, we determined the optimal reduction conditions for wet chemical growth, namely a reducing agent concentration of approximately 34.21 mM. Figure 4 As shown, within this growth window, the synthesized platinum nanowires exhibit excellent uniformity and linear morphology. Beyond the suitable growth window, when the reducing agent reaches 60 mM, the reduction rate within the system is too rapid, causing platinum to remain free in the electrolyte due to insufficient time to deposit on the silica gel. Furthermore, the electrolyte turns black, resulting in a significant decrease in nanowire density and a predominance of platinum particles on the silica gel. Conversely, when the reducing agent concentration is too low, the reduction rate is too slow, resulting only in the formation of spherical particles.
[0037] In this invention, we systematically screened the factors affecting the surface roughness of platinum nanowires. For example... Figure 5 As shown, under high ligand concentrations, the ligands complex with the Pt precursor, hindering growth and reducing growth sites. However, more Pt at these growth sites is used for growth, resulting in longer nanowires with smoother surfaces. We believe this is because Pt nanowire growth follows anisotropic principles; different crystal planes, such as the (111) and (200) planes, have different surface energies, leading to variations in growth rates. Ligand molecules preferentially adsorb onto crystal planes with higher surface energies, forming a protective layer that inhibits growth on those planes. When the ligand concentration is low, the ligands are insufficient to completely cover all high surface energy crystal planes, causing the uncovered planes to grow rapidly and readily undergo lateral growth, resulting in significant Pt self-nucleation.
[0038] This invention also successfully loads the material onto hydrophilic carbon paper. By successfully loading the catalyst onto this conductive substrate, the conductive material of well-dispersed platinum nanowires can be directly used as a working electrode, which reduces the inevitable loss of catalyst during the catalyst preparation process and the problem of loose bonding between the catalyst and the electrode. It has great application potential in electrocatalysis.
[0039] The product was analyzed using transmission electron microscopy, revealing the use of different ligands in the growth medium. Figure 2 The nanowires generated by different ligand types are shown. Weaker ligand effects result in more platinum particles, affecting nanowire growth. Unlike using a silicon substrate, when using 2-mercaptobenzimidazole-5-carboxylic acid as a ligand, the number of nanowires generated is extremely small, mostly nanoparticles. However, nanowires grown using 4-mercaptobenzoic acid exhibit the best morphology and density. Using other types of ligands, however, is limited by the ligand effect, leading to an even greater number of nanoparticles.
[0040] Nanowires (approximately 1 μm in length and 5 nm in diameter) grown using a 1:1 volume ratio of 5 mM APTES to acetic acid exhibited optimal morphology. In contrast, other conditions with equal volume ratios of APTES and acetic acid resulted in fewer nanowires due to the slower hydrolysis of APTES.
[0041] The optimal seed concentration is when diluted 10 times, which yields the best nanowires.
[0042] And as Figure 7As shown, by further refining the ligand concentration, comparing (a) 1 mM, (b) 0.8 mM, and (c) 0.5 mM, we can synthesize nanowires with different surface roughnesses, and the roughness gradually becomes more severe as the ligand concentration decreases. Simultaneously, comparing nanowires with different roughnesses (i.e., the ligand concentrations mentioned above are (a) 1 mM, (b) 0.8 mM, and (c) 0.5 mM), the nanowires with smoother surfaces exhibit higher ethanol oxidation activity, although their catalytic effect is significantly reduced but still slightly higher than that of commercial platinum-carbon catalytic activity. Attached Figure Description
[0043] Figure 1 The images show the effects of APTES on nanowire growth during silica pretreatment in this invention, including APTES concentration and the different effects of APTES acidification. a) silica was not treated with APTES; b) silica was treated with pure APTES; cf) pretreatment experiments were conducted using different APTES to acetic acid volume ratios, specifically (c) 1:1; (d) 1:5; (e) 1:10; (f) 1:20. The APTES concentration was 5 mM, and the acetic acid concentration was 17.4 M.
[0044] Figure 2 The images show the effects of different types of ligands on nanowire growth in this invention: (a) naphthiol; (b) 2-mercaptobenzimidazole 5-carboxylic acid; (c) 4-mercaptophenylacetic acid; (d) 11-mercaptoundecanoic acid; (e) imidazole; and (f) 4-mercaptobenzoic acid.
[0045] Figure 3 The images show TEM images of nanowires grown in the growth solution using different concentrations of 4-mercaptobenzoic acid in this invention. The specific reaction conditions are (a) 0 mM; (b) 1 mM; (c) 5 mM; and (d) 10 mM.
[0046] Figure 4 The images show TEM images of nanowires obtained under different concentrations of sodium borohydride in the growth solution during the present invention: (a) 17.11 mM; (b) 34.21 mM; (c) 68.42 mM; (d) 136.84 mM.
[0047] Figure 5 TEM images of nanowires grown using different seed concentrations in this invention: (a) undiluted; (b) diluted 10 times; (c) diluted 50 times; (d) diluted 100 times.
[0048] Figure 6TEM images of Pt nanowires grown at different times, with deposition times of 1 min, 5 min, 10 min, 15 min, 30 min, and 60 min, were obtained on silica in solution.
[0049] Figure 7 These are TEM images of platinum nanowires with different surface roughnesses grown at different ligand concentrations: (a) 1 mM; (b) 0.5 mM; (c) 0.2 mM.
[0050] Figure 8 The area activity map was obtained by cyclic voltammetry (CV) when platinum nanowires grown on hydrophilic carbon paper and conventional commercial platinum carbon were used as catalysts for ethanol oxidation. Detailed Implementation
[0051] The present invention will be further described below with reference to specific embodiments and accompanying drawings.
[0052] Example 1
[0053] (1) First, under acidic conditions, a solution of triaminopropyltriethoxysilane APTES with a total volume of 600 μL was used to ammoniate 20 μL of 60 nm silica in the solution for 20 min. The concentration of triaminopropyltriethoxysilane was 5 mM. APTES was dissolved in equal volumes of ethanol and water at a ratio of 1:1. Ethanol was added first and then water was added during preparation to prevent excessive hydrolysis of the silane coupling agent. After APTES was prepared, it was mixed with 17.4 M acetic acid at volume ratios of 1:1, 1:5, 1:10, and 1:20 to treat silica.
[0054] (2) Take out the silica from step (1) and centrifuge it to wash away the excess APTES solution. Then add 150 μL of water and 150 μL of ethanol, for a total of 300 μL of solution without APTES. Mix it with 17.4 M acetic acid at volume ratios of 1:1, 1:5, 1:10, and 1:20. Take 600 μL and add it to the system. Then add 100 μL of 3-5 nm platinum particle solution diluted 10 times with water and soak for 2 h. The synthesis method of the 3-5 nm platinum particles is to add chloroplatinic acid aqueous solution (0.205 M, 37 μL) and 1 wt% ammonium citrate aqueous solution (200 μL) to 14 mL of ultrapure water. Stir at 800 rpm until homogeneous. Then add 600 μL of 0.1 M sodium borohydride solution prepared with ice water and stir for 10 minutes to complete the reaction.
[0055] (3) Take out the substrate from step (2) and centrifuge to wash away the excess platinum particle solution. In order to ensure that the overall volume and pH of the solution remain unchanged, 700 μL of the original solution needs to be added, including 250 μL of water, 150 μL of ethanol and 300 μL of acetic acid. Then prepare the growth solution.
[0056] (4) The growth solution consists of chloroplatinic acid, 4-mercaptobenzoic acid and sodium borohydride; the growth solution is composed of water and ethanol in a volume ratio of 1:1, and the volume of the growth solution is 300 μL. Chloroplatinic acid is used as a metal precursor, 4-mercaptobenzoic acid is used as a ligand, and sodium borohydride is used as a reducing agent. The concentration of chloroplatinic acid is 10.81 mM, the concentration of the ligand is 1 mM, and the concentration of the reducing agent is 34.21 mM. The precursor, ligand and reducing agent are added to the solution in sequence, with 100 μL of each added.
[0057] (5) The synthesis was carried out using a wet chemical method with a reaction time of 60 min. After the reaction was completed, the solution was washed with ethanol and water and dried before characterization. The reaction solution turned black uniformly, indicating that the platinum nanowires were successfully synthesized.
[0058] Figure 1 The images show the effects of APTES on nanowire growth during silica pretreatment in this invention, including APTES concentration and the different effects of APTES acidification. a) silica was not treated with APTES; b) silica was treated with pure APTES; cf) pretreatment experiments were conducted using different APTES to acetic acid volume ratios, specifically (c) 1:1; (d) 1:5; (e) 1:10; (f) 1:20. The APTES concentration was 5 mM, and the acetic acid concentration was 17.4 M.
[0059] The product was analyzed using a transmission electron microscope, such as Figure 1 As shown, silica without APTES treatment only yields a dense layer of platinum nanoparticles. However, with increasing APTES acidification, lateral growth and nucleation of nanoparticles gradually occur on the substrate surface, and their density decreases. Furthermore, the hydrolysis rate of untreated APTES is too fast, resulting in the formation of more nanoparticles. Nanowires (approximately 1 μm in length and 5 nm in diameter) grown using a 1:1 volume ratio of 5 mM APTES to acetic acid exhibit the best morphology. Compared to other conditions with equal volume ratios of APTES and acetic acid, the slower hydrolysis of APTES leads to a decrease in the number of nanowires formed.
[0060] Example 2
[0061] (1) First, under acidic conditions, 600 μL of triaminopropyltriethoxysilane APTES solution was used to ammoniate 20 μL of 60 nm silica in the solution phase for 20 min. The concentration of triaminopropyltriethoxysilane was 5 mM (1.10685 mg / mL). APTES was dissolved in equal volumes of ethanol and water at a ratio of 1:1. Ethanol was added first and then water was added during preparation to prevent excessive hydrolysis of the silane coupling agent. After the APTES was prepared, it was mixed with 17.4 M acetic acid at a volume ratio of 1:1 to treat the silica.
[0062] (2) Take out the silica from step (1) and centrifuge it to wash away the excess APTES solution. Then add 150 μL of water, 150 μL of ethanol and 300 μL of acetic acid solution that does not contain APTES to ensure that the solution volume and pH conditions in the system remain unchanged. Add 100 μL of 3~5 nm platinum particle solution diluted 10 times with water and soak for 2 h.
[0063] (3) Take out the substrate from step (2) and centrifuge to wash away the excess platinum particle solution. In order to ensure that the overall volume and pH of the solution remain unchanged, 700 μL of the original solution needs to be added, including 250 μL of water, 150 μL of ethanol and 300 μL of acetic acid. Then prepare the growth solution.
[0064] (4) The growth solution consists of a precursor, a ligand, and a reducing agent. The growth solution is composed of water and ethanol, and the volume of the growth solution is 300 μL. Chloroplatinic acid is used as a metal precursor, sodium borohydride is used as a reducing agent, and different ligands are selected for condition screening. The concentration of chloroplatinic acid is 10.81 mM, the concentration of the ligand is 0.5 mM, and the concentration of the reducing agent is 34.21 mM. The precursor, ligand, and reducing agent are added to the solution in sequence, with 100 μL of each added.
[0065] (5) The synthesis was carried out using a wet chemical method with a reaction time of 60 min. After the reaction was completed, the solution was washed with ethanol and water and dried before characterization. The reaction solution turned black uniformly, indicating that the platinum nanowires were successfully synthesized.
[0066] Figure 2 The images show the effects of different types of ligands on nanowire growth in this invention: (a) naphthiol; (b) 2-mercaptobenzimidazole 5-carboxylic acid; (c) 4-mercaptophenylacetic acid; (d) 11-mercaptoundecanoic acid; (e) imidazole; and (f) 4-mercaptobenzoic acid.
[0067] The product was analyzed using transmission electron microscopy, revealing the use of different ligands in the growth medium. Figure 2The nanowires generated by different ligand types are shown. Weaker ligand effects result in more platinum particles, affecting nanowire growth. Unlike using a silicon substrate, when using 2-mercaptobenzimidazole-5-carboxylic acid as a ligand, the number of nanowires generated is extremely small, mostly nanoparticles. However, nanowires grown using 4-mercaptobenzoic acid exhibit the best morphology and density. Using other types of ligands, however, is limited by the ligand effect, leading to an even greater number of nanoparticles.
[0068] Example 3
[0069] (1) First, under acidic conditions, 600 μL of triaminopropyltriethoxysilane APTES solution was used to ammoniate 20 μL of 60 nm silica in the solution phase for 20 min. The concentration of triaminopropyltriethoxysilane was 5 mM (1.10685 mg / mL). APTES was dissolved in equal volumes of ethanol and water at a ratio of 1:1. Ethanol was added first and then water was added to prevent excessive hydrolysis of the silane coupling agent. After the APTES was prepared, it was mixed with 17.4 M acetic acid at a ratio of 1:1 to treat the silica.
[0070] (2) Take out the silica from step (1) and centrifuge it to wash away the excess APTES solution. Then add 150 μL of water, 150 μL of ethanol and 300 μL of acetic acid solution that does not contain APTES to ensure that the solution volume and pH conditions in the system remain unchanged. Add 100 μL of 3~5 nm platinum particle solution diluted 10 times with water and soak for 2 h.
[0071] (3) Take out the substrate from step (2) and centrifuge to wash away the excess platinum particle solution. In order to ensure that the overall volume and pH of the solution remain unchanged, 700 μL of the original solution needs to be added, including 250 μL of water, 150 μL of ethanol and 300 μL of acetic acid. Then prepare the growth solution.
[0072] (4) The growth solution consists of chloroplatinic acid, 4-mercaptobenzoic acid and sodium borohydride; the growth solution is composed of water and ethanol, and the volume of the growth solution is 300 μL. Chloroplatinic acid is used as a metal precursor, 4-mercaptobenzoic acid is used as a ligand, and sodium borohydride is used as a reducing agent. The concentration of chloroplatinic acid is 10.81 mM, the concentration of the ligand is 0-10 mM, and the concentration of the reducing agent is 34.21 mM. The precursor, ligand and reducing agent are added to the solution in sequence, with 100 μL of each added.
[0073] (5) The synthesis was carried out using a wet chemical method with a reaction time of 60 min. After the reaction was completed, the solution was washed with ethanol and water and dried before characterization. The reaction solution turned black uniformly, indicating that the platinum nanowires were successfully synthesized.
[0074] Figure 3The images show TEM images of nanowires grown in the growth solution using different concentrations of 4-mercaptobenzoic acid in this invention. The specific reaction conditions are (a) 0 mM; (b) 1 mM; (c) 5 mM; and (d) 10 mM.
[0075] The product was analyzed using a transmission electron microscope, such as Figure 3 As shown, no nanowires can be obtained without adding any ligands, only platinum particles. As the ligand concentration gradually increases, nanowires are gradually generated. When the ligand concentration is 1 mM, uniformly distributed and densely grown platinum nanowires can be obtained. However, when the ligand concentration is too high, up to 10 mM, the density and length of the nanowires gradually decrease. At this point, a large amount of platinum exists in the form of particles.
[0076] Example 4
[0077] (1) First, under acidic conditions, 600 μL of triaminopropyltriethoxysilane APTES solution was used to ammoniate 20 μL of 60 nm silica in the solution phase for 20 min. The concentration of triaminopropyltriethoxysilane was 5 mM (1.10685 mg / mL). APTES was dissolved in equal volumes of ethanol and water at a ratio of 1:1. Ethanol was added first and then water was added to prevent excessive hydrolysis of the silane coupling agent. After the APTES was prepared, it was mixed with 17.4 M acetic acid at a ratio of 1:1 to treat the silica.
[0078] (2) Take out the silica from step (1) and centrifuge it to wash away the excess APTES solution. Then add 150 μL of water, 150 μL of ethanol and 300 μL of acetic acid solution that does not contain APTES to ensure that the solution volume and pH conditions in the system remain unchanged. Add 100 μL of 3~5 nm platinum particle solution diluted 10 times with water and soak for 2 h.
[0079] (3) Take out the substrate from step (2) and centrifuge to wash away the excess platinum particle solution. In order to ensure that the overall volume and pH of the solution remain unchanged, 700 μL of the original solution needs to be added, including 250 μL of water, 150 μL of ethanol and 300 μL of acetic acid. Then prepare the growth solution.
[0080] (4) The growth solution consists of chloroplatinic acid, 4-mercaptobenzoic acid and sodium borohydride; the growth solution is composed of water and ethanol, and the volume of the growth solution is 300 μL. Chloroplatinic acid is used as a metal precursor, 4-mercaptobenzoic acid is used as a ligand, and sodium borohydride is used as a reducing agent. The concentration of chloroplatinic acid is 10.81 mM and the concentration of the ligand is 1 mM. The concentration range of the reducing agent is 17.11-136.84 mM. The precursor, ligand and reducing agent are added to the solution in sequence, with 100 μL of each added.
[0081] (5) The synthesis was carried out using a wet chemical method with a reaction time of 60 min. After the reaction was completed, the solution was washed with ethanol and water and dried before characterization. The reaction solution turned black uniformly, indicating that the platinum nanowires were successfully synthesized.
[0082] Figure 4 The images show TEM images of nanowires obtained under different concentrations of sodium borohydride in the growth solution during the present invention: (a) 17.11 mM; (b) 34.21 mM; (c) 68.42 mM; (d) 136.84 mM.
[0083] The product was analyzed using a transmission electron microscope. Figure 4 As shown, when the reducing agent concentration is as low as 34.21 mM, platinum is difficult to reduce and therefore cannot be reduced into nanowires. However, as the reducing agent concentration gradually increases, well-shaped and uniformly distributed nanowires are formed. But when the reducing agent concentration is higher than 34.21 mM, its excessive reducing power affects the growth of nanowires, causing them to tend to form sheets, resulting in only spherical nanoparticles. A reducing agent concentration of 34.21 mM is the optimal concentration, resulting in the best nanowire growth.
[0084] Example 5
[0085] (1) First, under acidic conditions, 600 μL of triaminopropyltriethoxysilane APTES solution was used to ammoniate 20 μL of 60 nm silica in the solution phase for 20 min. The concentration of triaminopropyltriethoxysilane was 5 mM (1.10685 mg / mL). APTES was dissolved in equal volumes of ethanol and water at a ratio of 1:1. Ethanol was added first and then water was added to prevent excessive hydrolysis of the silane coupling agent. After the APTES was prepared, it was mixed with 17.4 M acetic acid at a ratio of 1:1 to treat the silica.
[0086] (2) Take out the silica from step (1) and centrifuge it to wash away the excess APTES solution. Then add 150 μL of water, 150 μL of ethanol and 300 μL of acetic acid solution that does not contain APTES to ensure that the solution volume and pH conditions in the system remain unchanged. Add 100 μL of water diluted with different multiples of 3~5 nm platinum particle aqueous solution and soak for 2 h.
[0087] (3) Take out the substrate from step (2) and centrifuge to wash away the excess platinum particle solution. In order to ensure that the overall volume and pH of the solution remain unchanged, 700 μL of the original solution needs to be added, including 250 μL of water, 150 μL of ethanol and 300 μL of acetic acid. Then prepare the growth solution.
[0088] (4) The growth solution consists of chloroplatinic acid, 4-mercaptobenzoic acid and sodium borohydride; the growth solution is composed of water and ethanol, and the volume of the growth solution is 300 μL. Chloroplatinic acid is used as a metal precursor, 4-mercaptobenzoic acid is used as a ligand, and sodium borohydride is used as a reducing agent. The concentration of chloroplatinic acid is 10.81 mM, the concentration of the ligand is 1 mM, and the concentration range of the reducing agent is 34.21 mM. The precursor, ligand and reducing agent are added to the solution in sequence, with 100 μL added for each.
[0089] (5) The synthesis was carried out using a wet chemical method with a reaction time of 60 min. After the reaction was completed, the solution was washed with ethanol and water and dried before characterization. The reaction solution turned black uniformly, indicating that the platinum nanowires were successfully synthesized.
[0090] Figure 5 TEM images of nanowires grown using different seed concentrations in this invention: (a) undiluted; (b) diluted 10 times; (c) diluted 50 times; (d) diluted 100 times.
[0091] Transmission electron microscopy analysis showed that the density of the nanowires could be further controlled by adding platinum seed solutions of different dilution ratios. Figure 5 As shown, the density of the nanowires exhibits different sparsity depending on the platinum seed solution concentration. When the platinum seeds are excessively diluted, a large amount of precursor is reduced to particles, drastically reducing the number of nanowires and resulting in only a large number of platinum particles. Conversely, using undiluted seeds leads to an imbalance in the local reduction environment due to excessive growth sites, resulting in simultaneous spontaneous and secondary nucleation, which severely affects the directional growth of the nanowires. The optimal seed concentration is a 10-fold dilution, yielding the best nanowires.
[0092] Example 6
[0093] (1) First, under acidic conditions, 600 μL of triaminopropyltriethoxysilane APTES solution was used to ammoniate 20 μL of 60 nm silica in the solution phase for 20 min. The concentration of triaminopropyltriethoxysilane was 5 mM (1.10685 mg / mL). APTES was dissolved in equal volumes of ethanol and water at a ratio of 1:1. Ethanol was added first and then water was added to prevent excessive hydrolysis of the silane coupling agent. After the APTES was prepared, it was mixed with 17.4 M acetic acid at a ratio of 1:1 to treat the silica.
[0094] (2) Take out the silica from step (1) and centrifuge it to wash away the excess APTES solution. Then add 150 μL of water, 150 μL of ethanol and 300 μL of acetic acid solution that does not contain APTES to ensure that the solution volume and pH conditions in the system remain unchanged. Add 100 μL of 3~5 nm platinum particle solution diluted 10 times with water and soak for 2 h.
[0095] (3) Take out the substrate from step (2) and centrifuge to wash away the excess platinum particle solution. In order to ensure that the overall volume and pH of the solution remain unchanged, 700 μL of the original solution needs to be added, including 250 μL of water, 150 μL of ethanol and 300 μL of acetic acid. Then prepare the growth solution.
[0096] (4) The growth solution consists of chloroplatinic acid, 4-mercaptobenzoic acid and sodium borohydride; the growth solution is composed of water and ethanol, and the volume of the growth solution is 300 μL. Chloroplatinic acid is used as a metal precursor, 4-mercaptobenzoic acid is used as a ligand, and sodium borohydride is used as a reducing agent. The concentration of chloroplatinic acid is 10.81 mM, the concentration of the ligand is 1 mM, and the concentration of the reducing agent is 34.21 mM. 100 μL of each of the precursor, ligand and reducing agent are added to the solution in sequence.
[0097] (5) The synthesis uses a wet chemical method. The reaction time is controlled within 1-60 min. After the reaction is completed, the solution is washed with ethanol and water and dried before characterization. The reaction solution turns black uniformly, which indicates that the platinum nanowires have been successfully synthesized.
[0098] Figure 6 TEM images of Pt nanowires grown at different times, with deposition times of 1 min, 5 min, 10 min, 15 min, 30 min, and 60 min, were obtained on silica in solution.
[0099] Scanning electron microscopy analysis of the product revealed that, after different reaction controls for growing platinum nanowires, the optimal growth conditions were: 10.81 mM chloroplatinic acid, 1 mM ligand concentration, and 34.21 mM reducing agent concentration. Furthermore... Figure 6 As shown, the length of the nanowires increases linearly with deposition time, with lengths of 1 nm, 15 nm, 100 nm, 400 nm, 800 nm, and 1 μm, and a diameter of 5 nm for platinum nanowires.
[0100] And as Figure 7 As shown, by further refining the ligand concentration, we can synthesize nanowires with different surface roughness by comparing (a) 1 mM, (b) 0.8 mM, and (c) 0.5 mM. The roughness gradually becomes more severe as the ligand concentration decreases.
[0101] Catalytic testing was conducted by loading platinum nanowires onto a conductive substrate, which was hydrophilic carbon paper. Specifically, 1 mg of the prepared platinum nanowires were dispersed in 500 μL of water and a 2.5% (v / v) naphthol solution, and then uniformly sprayed onto the surface of the carbon paper using a spray gun.
[0102] Platinum nanowires loaded onto conductive substrates can be directly used in catalytic reactions, reducing problems such as catalyst loss or weak bonding between the catalyst and the electrode in traditional catalyst preparation processes, and greatly promoting the development of electrocatalysis.
[0103] Electrochemical tests were then performed using a three-electrode system: a platinum sheet electrode as the counter electrode; a saturated calomel electrode (SCE) as the reference electrode; and a hydrophilic carbon paper loaded with platinum nanowires as the working electrode. The electrolyte consisted of a 0.5 M KOH and a 0.5 M ethanol aqueous solution. Cyclic voltammetry (CV) was performed at a scan rate of 50 mV / s.
[0104] Figure 8 Area activity maps measured by cyclic voltammetry (CV) when platinum nanowires of different lengths are grown on hydrophilic carbon paper and when conventional commercial platinum carbon is used as a methanol oxidation catalyst.
[0105] like Figure 8 As shown, electrochemical tests indicate that the longer the growth time of platinum nanowires, the greater their mass activity. Under the optimal conditions described above—namely, a growth solution of 10.81 mM chloroplatinic acid, a ligand concentration of 1 mM, and a reducing agent concentration of 34.21 mM—the surface activity of 1 μm-long platinum nanowires reached 15018 mA / mg. -2 The surface activity of commercial Pt / C is only 2200 mA / mg. -2 Therefore, the current density of solution-grown platinum nanowires exhibits 8 times the catalytic efficiency for ethanol oxidation compared to traditional commercial platinum-carbon.
[0106] Meanwhile, comparing nanowires with different roughness levels (i.e., ligand concentrations of (a) 1 mM (b) 0.8 mM (c) 0.5 mM), the nanowires with smoother surfaces exhibit higher ethanol oxidation activity. This is because the rougher nanowires are constrained by the decrease in ligand concentration, resulting in an increase in the number of nuclei formed. Therefore, their catalytic effect is significantly reduced, but still slightly higher than that of commercial platinum-carbon catalytic activity.
[0107] This invention is not limited to the specific technical solutions described in the above embodiments. Any modification or equivalent substitution of this invention to achieve the same technical effect is within the scope of protection of this invention.
Claims
1. A simple wet chemical method for solution phase growth of ultrafine platinum super-long nanowires, characterized in that :comprising the following steps: (1) first, using the solution of triaminopropyl triethoxysilane APTES to amino treatment of silica under acidic conditions; the acid is acetic acid; the concentration is 5 mM APTES and the concentration is 17.4 M acetic acid according to the volume ratio 1:1 mixed into silica and then treated; the total volume of the solution is 600 μL; (2) the substrate in step (1) is taken out to wash away the excess APTES solution, and 150 μL of water, 150 μL of ethanol and 300 μL of acetic acid are added to the original solution and 100 μL of 3-5 nm platinum particle aqueous solution diluted by 10 times, and soaked for 120 min; (3) the substrate in step (2) is taken out and centrifuged to wash away the excess platinum particle solution, in order to ensure the overall volume and pH of the solution unchanged, 700 μL of the original solution needs to be supplemented, wherein water 250 μL, ethanol 150 μL, acetic acid 300 μL, and then the growth solution is prepared; (4) the composition of the growth solution is 100 μL of 10.81 mM chloroplatinic acid, 100 μL of 1 mM 4-mercaptobenzoic acid and 100 μL of 34.21 mM sodium borohydride; the growth solution is composed of water and ethanol with a volume ratio of 1:1, wherein chloroplatinic acid is used as a metal precursor, 4-mercaptobenzoic acid is used as a ligand, and sodium borohydride is used as a reducing agent, and the total volume of the growth solution is 300 μL; the growth solution is added to the solution obtained in step (3); (5) the synthesis method uses wet chemical method, the concentration of reducing agent sodium borohydride is 34.21 mM, the reaction time is controlled within 60 min, and platinum nanowires are synthesized.
2. The simple wet chemical method for synthesis of platinum nanowires in solution phase as claimed in claim 1 wherein: The synthesis method of 3-5 nm platinum particles in step (2) is to add chloroplatinic acid aqueous solution (0.205 M, 37 μL) and 1 wt% ammonium citrate aqueous solution (200 μL) into 14 mL of ultrapure water, stir uniformly at 800 rpm, then add 0.1 M sodium borohydride solution prepared by ice water 600 μL, stir for 10 minutes, and complete the reaction.
3. The simple wet chemical method for solution phase growth of ultrafine platinum ultralong nanowires as claimed in claim 1, wherein :comprising the following steps: (1) first, using the solution of triaminopropyl triethoxysilane APTES to amino treatment of silica under acidic conditions; the acid is acetic acid; the concentration is 5 mM APTES and the concentration is 17.4 M acetic acid according to the volume ratio 1:1 mixed into silica and then treated; the total volume of the solution is 600 μL; (2) the silica in step (1) is centrifuged, the excess APTES solution is washed away, and the original solution without APTES is supplemented to 600 μL and 100 μL of 3~5 nm platinum particle solution is added; (3) the substrate in step (2) is taken out and centrifuged to wash away the excess platinum particle solution, in order to ensure the overall volume and pH of the solution unchanged, 700 μL of the original solution needs to be supplemented, wherein water 250 μL, ethanol 150 μL, acetic acid 300 μL then prepare the growth solution; (4) the composition of the growth solution is chloroplatinic acid, 4-mercaptobenzoic acid and sodium borohydride; the growth solution is composed of water and ethanol, wherein chloroplatinic acid is used as a metal precursor, 4-mercaptobenzoic acid is used as a ligand, and sodium borohydride is used as a reducing agent, and the concentration of chloroplatinic acid is 10.81 mM, and the concentration of ligand is 1 mM; (5) The synthesis method uses a wet chemical method, the reducing agent concentration is 34.21 mM, the reaction time is controlled at 60 min, platinum nanowires are synthesized, after the reaction is completed, the product is collected by centrifugation, and is washed with water and ethanol, and is dried before characterization, and is loaded on carbon paper.
4. The simple wet chemical method for solution phase growth of ultrafine platinum ultralong nanowires as claimed in claim 1, wherein: 60 nm size silica in solution phase is used as the substrate of the solution phase reaction.
5. The ultra-long platinum nanowires synthesized in solution phase by simple wet chemical method as claimed in claim 1, wherein The platinum nanowires are loaded on a conductive substrate for catalytic testing, and the substrate is hydrophilic carbon paper.
6. The ultra-long platinum nanowires synthesized in solution phase by simple wet chemical method as claimed in claim 1, wherein The method comprises the following steps: (1) First, 20 μL of 60 nm size silica in solution phase is subjected to an amination treatment for 20 min under acidic conditions using 600 μL of aminopropyl triethoxysilane (APTES) solution, the concentration of the aminopropyl triethoxysilane is 5 mM, the APTES is dissolved in an equal volume of ethanol and water in a 1:1 ratio, the ethanol is added first and then the water is added when the APTES is prepared, to prevent excessive hydrolysis of the silane coupling agent, and the prepared APTES is mixed with an equal volume of 17.4 M acetic acid to further treat the silica; (2) The silica in step (1) is taken out and centrifuged, and the excess APTES solution is washed away, then 150 μL of water, 150 μL of ethanol and 300 μL of acetic acid solution without APTES are added, to ensure that the solution volume and pH conditions in the system remain unchanged, and 100 μL of 3-5 nm platinum particle solution diluted 10 times with water is added and soaked for 2 h; (3) The substrate in step (2) is taken out and centrifuged to wash away the excess platinum particle solution, 700 μL of the original solution is added to ensure that the solution volume and pH remain unchanged, wherein the water is 250 μL, the ethanol is 150 μL, and the acetic acid is 300 μL, and then the growth solution is prepared; (4) The growth solution is composed of chloroplatinic acid, 4-mercaptobenzoic acid and sodium borohydride; the growth solution is composed of water and ethanol, wherein the chloroplatinic acid serves as a metal precursor, the 4-mercaptobenzoic acid serves as a ligand, and the sodium borohydride serves as a reducing agent, the concentration of the chloroplatinic acid is 10.81 mM, the concentration of the ligand ranges from 1 mM, and the concentration of the reducing agent is 34.21 mM, which is sequentially added to the solution; (5) The synthesis method uses a wet chemical method, the reaction time is 60 min, after the reaction is completed, the product is washed with ethanol and water, and dried before characterization, and the reaction solution uniformly turns black, indicating that the platinum nanowires are successfully synthesized.
7. Use of platinum nanowires prepared according to any of the methods of claims 1-6, characterized in that: The platinum nanowires can be used in the field of fuel cells or electrochemical catalysis.