Crystalline platinum dioxide catalyst and electrochemical preparation method thereof

Abstract

The electrochemical preparation method comprises the following steps: preparing Pt (100) nano-particles, and loading the Pt (100) nano-particles on a glassy carbon electrode by using an aqueous solution to serve as a working electrode; the working electrode is placed in an electrolyte solution, and the concentration of perchlorate ions is adjusted, so that the adsorption quantity of the non-specific adsorption perchlorate ions on the surfaces of the Pt (100) nanoparticles is increased; the potential and the potential duration time of the constant potential step process are adjusted, specifically, the constant potential step process is increased to 1.4 V from 0.15 V, the duration time of each potential step is 380 s, and the constant potential is 1.4 V and lasts for gt; the crystal state of platinum dioxide is determined through Raman spectrum measurement; and adjusting the pH value of the electrolyte solution and the concentration of perchlorate ions, and controlling to obtain the required crystalline platinum dioxide catalyst. According to the invention, the preparation process of the catalyst can be more accurately controlled, the operation process is simplified, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to a crystalline platinum dioxide catalyst and an electrochemical preparation method thereof, belonging to the technical field of electrochemistry. Background Art

[0002] Platinum dioxide catalyst is a metal oxide catalyst with high activity and good stability. It has high stability and can be reduced by hydrogen to obtain a platinum catalyst. It has a large number of active adsorption sites and is widely used in the chemical industry, such as as a hydrogenation catalyst in organic synthesis. It can hydrogenate a variety of groups and requires mild reaction conditions. It is an excellent hydrogen absorption material. Therefore, it has broad application prospects in the field of catalysis. The traditional method for preparing platinum dioxide is mainly to mix chloroplatinic acid or ammonium chloroplatinate with sodium nitrate and carry out a eutectic reaction at high temperature. The resulting mixture is subjected to post-treatment steps such as water washing and drying to finally obtain platinum dioxide. Although the above preparation method is relatively mature and easy to control and mass produce, it still has defects: (1) In order to ensure that the reaction is complete, the sodium nitrate used in the traditional method is greatly excessive, which not only increases the cost of raw materials, but also may lead to resource waste; (2) The traditional method requires a long reaction or roasting at high temperature, which not only consumes a lot of energy, but also may increase production costs and age the reactor; (3) The traditional method usually includes multiple steps, such as dissolution, precipitation, filtration, drying, etc., which not only increases the complexity of the operation, but also prolongs the production cycle.

[0003] Therefore, the traditional method has the problems of high cost, complicated process, waste of resources, etc. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a crystalline platinum dioxide catalyst and an electrochemical preparation method thereof, which can optimize the preparation conditions, simplify the preparation process and reduce the preparation cost.

[0005] In order to achieve the above object, the present invention adopts an electrochemical preparation method of a crystalline platinum dioxide catalyst, comprising the following steps:

[0006] S1. Prepare Pt(100) nanoparticles and directly load them on a glassy carbon electrode using an aqueous solution as a working electrode;

[0007] S2, placing the working electrode of step S1 in an electrolyte solution, wherein the electrolyte solution includes 0.1-1.0M perchloric acid and 1.0-3.0M sodium perchlorate solution, and adjusting the concentration of perchlorate ions to increase the amount of non-specific adsorption of perchlorate ions on the surface of Pt(100) nanoparticles; it should be noted that non-specific adsorption refers to the adsorption of a substance on a surface that does not depend on specific interactions or coordination bonds between molecules. This adsorption occurs when the solution contacts a solid surface, and due to non-covalent bond forces, such as van der Waals forces, electrostatic forces, and hydrophobic effects, the compound is adsorbed onto the solid surface;

[0008] S3, adjusting the potential and potential duration of the constant potential step process, including: the constant potential step process increases from 0.15V to 1.4V, the duration of each potential step is 380s, the constant potential is 1.4V and lasts for >1h, and the crystalline state of platinum dioxide is determined by Raman spectroscopy;

[0009] S4. Adjusting the pH value and the concentration of perchlorate ions in the electrolyte solution to obtain the desired crystalline platinum dioxide catalyst.

[0010] As an improvement, in step S1, a colloidal method is used to prepare Pt (100) nanoparticles with clean surface, controllable shape and easy access.

[0011] As an improvement, the colloid method includes the steps of: adding sodium hydroxide to a potassium chloroplatinate and sodium polyacrylate solution with a pH of 6-8 to induce precipitation, washing the precipitate, and obtaining Pt (100) nanoparticles.

[0012] As an improvement, the molar concentration ratio of potassium chloroplatinate to sodium polyacrylate is 1:(4-6).

[0013] As an improvement, in step S1, the Pt(100) nanoparticles are evenly dispersed by ultrasonication, and 8 ul is taken each time and dropped onto the glassy carbon electrode twice. When the nanoparticles are dry, the loading is completed.

[0014] As an improvement, in step S2, the concentration of perchlorate ions is adjusted to 1.0-3.0M.

[0015] The second aspect of the present invention also provides a crystalline platinum dioxide catalyst prepared by the electrochemical preparation method.

[0016] Mechanism of the present invention:

[0017] The perchlorate ions accumulated on the Pt(100) surface and the hydronium ions in the solution affect the adsorption of water on the Pt(100) surface. The perchlorate ions pull the water outward from the interface, and the hydronium ions push the adsorbed water outward, both of which are not conducive to the surface adsorption of water. The oxygen in platinum dioxide comes from the surface adsorbed water. Therefore, when the surface adsorption of surface adsorbed water is inhibited, it will affect the diffusion of oxygen into the platinum lattice, and then affect the type of platinum dioxide generated. If the oxygen diffuses quickly, amorphous platinum dioxide is formed, and if the oxygen diffuses slowly, crystalline platinum dioxide is formed.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention can achieve fine control of the morphology and structure of platinum dioxide nanomaterials by precisely controlling electrolyte conditions and potential parameters. This method makes the catalyst preparation process simpler and reduces costs. In contrast, traditional methods are often difficult to achieve such fine control, resulting in the catalyst preparation process requiring a large amount of raw materials and complex preparation processes. Therefore, the preparation of platinum dioxide by electrochemical methods can significantly reduce reaction time and steps, greatly improving production efficiency.

[0020] 2. The present invention combines in-situ characterization technology to monitor the changes in the electrode surface during the reaction in real time, and deeply understands the electrochemical process of platinum dioxide preparation under different electrolyte conditions. The application of this technical means makes the preparation process more controllable and simple, which helps to improve the production efficiency of platinum dioxide. Traditional methods lack this real-time monitoring capability.

[0021] 3. The preparation method of the present invention is efficient and accurate, avoiding unnecessary waste and duplication of labor, and does not require a large amount of raw materials. The reaction can be carried out at room temperature, which helps to reduce production costs and achieve green and low-carbon production. In contrast, the traditional method requires more raw materials and energy input, continuous high temperature reaction, and more complicated post-processing steps, resulting in higher production costs.

[0022] 4. The raw materials of the present invention include potassium chloroplatinate, perchloric acid, etc., which are in sufficient supply in the market and have relatively stable prices. The equipment required by the present invention has mature products in the market, and the process of the present invention is relatively simple, easy to master and operate, and therefore has broad prospects for industrialization and industrialization, and can be mass-produced.

[0023] 5. The electrochemical preparation of platinum dioxide can improve its electrochemical efficiency, reduce production costs and energy consumption by optimizing electrode materials, electrolyte pH and potential parameters, selecting appropriate electrolyte types and concentrations, and improving energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 TEM characterization of the morphology of Pt(100) nanoparticles synthesized in Example 1 of the present invention Figure 1 ;

[0026] Figure 2 TEM characterization of the morphology of Pt(100) nanoparticles synthesized in Example 1 of the present invention Figure 2 ;

[0027] Figure 3 For Example 2 of the present invention, the working electrode was placed in 0.1M perchloric acid, 0M and 3.0M sodium perchlorate were added, and Raman spectroscopy characterization diagrams were performed on the surface of Pt(100) nanoparticles during the constant potential step process;

[0028] Figure 4 For Example 3 of the present invention, the working electrode was placed under different pH conditions, the ion concentrations of 0-0.1M perchloric acid and 0-3.0M perchlorate were adjusted, and Raman spectroscopy of the surface of Pt(100) nanoparticles during the constant potential step process was performed;

[0029] Figure 5 For Example 4 of the present invention, the working electrode was placed in a 0.1M perchloric acid and 3.0M perchlorate ion solution at pH 1, and Raman spectra were recorded at different termination potentials;

[0030] Figure 6 This is a comparison chart of the Raman spectra of platinum dioxide in Example 5 of the present invention and commercial platinum dioxide. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clear, the technical solutions of the present application are described in detail below with the help of accompanying drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical solutions of the present application, rather than limitations on the technical solutions of the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0032] Example 1

[0033] A method for preparing Pt (100) nanoparticles comprises the following steps:

[0034] (1) The prepared 0.10 mM K2PtCl4 (potassium chloroplatinate) solution was subjected to dark aging treatment at 25°C for 24 h, and then 0.8 mL of 0.10 M sodium polyacrylate solution (molecular weight of about 2100 g / mol) was added to the aged K2PtCl4 solution to ensure that the molar concentration ratio of K2PtCl4 to sodium polyacrylate was maintained at 1:5, and then the pH value of the solution was adjusted to 7.5 using an appropriate amount of HCl;

[0035] (2) The prepared reaction solution was deoxygenated with argon for 20 min, and then hydrogen was introduced for reduction reaction for 8.0 min. The reaction vessel was sealed and left overnight to obtain a light golden solution.

[0036] (3) Two NaOH pellets were added to the liquid after the reaction was completed. After precipitation, the liquid was centrifuged at a speed of 10,000 rpm and rinsed with ultrapure water for multiple times (repeated 3 to 4 times) to completely remove the sodium polyacrylate on the surface of the nanoparticles to obtain Pt (100) nanoparticles. The Pt (100) nanoparticles were stored in 1.5 mL of ultrapure water.

[0037] Characterization of Pt(100) nanoparticles: The morphology of the Pt(100) nanoparticles synthesized in Example 1 was characterized using electron microscopy (TEM). Figure 1-Figure 2 As shown, analysis shows that the TEM image clearly shows that the Pt (100) nanoparticles have a regular cubic morphology, good dispersion, and clear contours and corners.

[0038] Example 2

[0039] The Pt(100) nanoparticles prepared in Example 1 were dispersed uniformly by ultrasonic, and 8 μl was taken each time and dropped onto the glassy carbon electrode twice. After the nanoparticles were dried, a working electrode was obtained.

[0040] The working electrode was placed in an electrolyte solution (including 0.1 M perchloric acid, 0 M sodium perchlorate solution), and the constant potential was increased from 0.15 V to 1.4 V, and each potential step lasted for 380 s.

[0041] As the concentration of perchlorate ions in the electrolyte solution gradually increased (from 0 M to 3.0 M), the Raman spectrum of the electrode surface increased from 590 cm -1 The single Raman peak shifted to 510 cm -1 and 550cm -1 The double Raman spectrum peaks indicate that crystalline platinum dioxide is obtained; 935cm -1 The Raman spectrum peak is the Raman shift of the Cl-O bond vibration of the perchlorate ion.

[0042] like Figure 3 As shown in the figure, when no sodium perchlorate solution is added to the 0.1M perchloric acid solution, the Raman spectrum shows 590cm -1 Single peak, when 3.0M sodium perchlorate solution is added to 0.1M perchloric acid solution, the Raman spectrum shows 515cm -1 and 561cm -1 Twin Peaks.

[0043] Example 3

[0044] preparing a Pt(100) nanoparticle-loaded working electrode;

[0045] In the non-specific adsorption of anion ClO4 - When the concentration remains unchanged, changing H + concentration to adjust the pH of the electrolyte solution;

[0046] In electrolytes with pH values ​​of 5.0, 3.0, 1.0, 0.5, 0.3, and 0.1, the working electrode loaded with Pt(100) nanoparticles was subjected to a constant potential step from 0.15 V to 1.4 V, with a step potential difference of 0.05 V, and each potential step lasted for 380 s, and the constant potential was maintained at 1.4 V for >1 h. At each potential, Raman spectroscopy was used to monitor the changes in the intensity of the platinum oxygen vibration peak signal in platinum dioxide.

[0047] like Figure 4 As shown in Figure 2, with the decrease of pH, the crystallinity of the prepared platinum oxide increases, and the -1 and 550cm -1 The signal intensity of the wave number band increases with the decrease of pH, and the difference between the signal intensities of the two bands becomes smaller and smaller with the decrease of pH, indicating that the decrease of pH is conducive to the preparation of α-PtO2 crystals.

[0048] Example 4

[0049] preparing a Pt(100) nanoparticle-loaded working electrode;

[0050] The working electrode was placed in an electrolyte solution of 0.1 M perchloric acid and 3.0 M sodium perchlorate, pH = 1, the starting potential of the constant potential step method was set to 0.15 V, the ending potentials were set to 1.1 V, 1.2 V, 1.3 V and 1.4 V respectively, the step potential difference was 0.05 V, each step potential was kept for 380 s, and Raman spectroscopy was used to monitor the platinum oxygen bond vibration peak of platinum dioxide generated by this potential.

[0051] like Figure 5 As shown in the figure, when the termination potential exceeds 1.2 V, platinum oxide species have been generated on the electrode surface. When it rises to 1.3 V, obvious Raman bands appear. As the potential continues to rise to 1.4 V, the band results are more obvious, and the 510 cm-1 and 550cm -1 The potential range is small, and when the high potential is low, it is impossible to clearly determine the change pattern of the Raman spectrum band as the potential increases.

[0052] Example 5

[0053] preparing a Pt(100) nanoparticle-loaded working electrode;

[0054] The working electrode was placed in a 0.1 M perchloric acid medium, a 3.0 M sodium perchlorate electrolyte solution, pH 1, and the constant potential step was increased from 0.15 V to 1.4 V, the step potential difference was 0.05 V, the duration of each potential was 380 s, and Raman spectroscopy detection was performed after a constant time of 1.4 V for > 1 h.

[0055] like Figure 6 As shown, at 511cm -1 and 556cm -1 The Raman spectrum at the wave number 10000 is consistent with the Raman shift of commercial platinum dioxide, indicating that the performance of the crystalline platinum dioxide prepared by this method meets the relevant requirements.

[0056] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. An electrochemical preparation method of a crystalline platinum dioxide catalyst, characterized in that: The following steps are involved: S1. Prepare Pt(100) nanoparticles and directly load them on a glassy carbon electrode using an aqueous solution as a working electrode; S2, placing the working electrode of step S1 in an electrolyte solution, wherein the electrolyte solution includes 0.1-1.0 M perchloric acid and 1.0-3.0 M sodium perchlorate solution, and adjusting the concentration of perchlorate ions to increase the amount of non-specifically adsorbed perchlorate ions on the surface of the Pt(100) nanoparticles; S3, adjusting the potential and potential duration of the constant potential step process, including: the constant potential step process increases from 0.15V to 1.4V, the duration of each potential step is 380s, the constant potential is 1.4V and lasts for >1h, and the crystalline state of platinum dioxide is determined by Raman spectroscopy; S4. Adjusting the pH value and the concentration of perchlorate ions in the electrolyte solution to obtain the desired crystalline platinum dioxide catalyst.

2. The electrochemical preparation method of a crystalline platinum dioxide catalyst according to claim 1, characterized in that: In the step S1, a colloidal method is used to prepare Pt (100) nanoparticles with clean surface, controllable shape and easy access.

3. The electrochemical preparation method of a crystalline platinum dioxide catalyst according to claim 2, characterized in that: The colloid method comprises the steps of: adding sodium hydroxide to a potassium chloroplatinate and sodium polyacrylate solution with a pH of 6-8 to induce precipitation, washing the precipitate, and obtaining Pt (100) nanoparticles.

4. The electrochemical preparation method of a crystalline platinum dioxide catalyst according to claim 3, characterized in that: The molar concentration ratio of potassium chloroplatinate to sodium polyacrylate is 1:(4-6).

5. The electrochemical preparation method of a crystalline platinum dioxide catalyst according to claim 1, characterized in that: In the step S1, the Pt(100) nanoparticles are evenly dispersed by ultrasonic, and 8 ul is taken each time and dropped on the glassy carbon electrode twice. When the nanoparticles are dry, the loading is completed.

6. The electrochemical preparation method of a crystalline platinum dioxide catalyst according to claim 1, characterized in that: In step S2, the concentration of perchlorate ions is adjusted to 1.0-3.0M.

7. A crystalline platinum dioxide catalyst, characterized in that: The electrochemical preparation method is adopted as claimed in any one of claims 1 to 6.

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