CN110625135B

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Publication number: CN110625135B
Application number: CN201910973734.0A
Authority: CN
Inventors: 张南; 张永亚; 王立晶; 王军梅; 魏伟; 瞿鹏
Original assignee: Shangqiu Normal University
Current assignee: Shangqiu Normal University
Priority date: 2019-10-14
Filing date: 2019-10-14
Publication date: 2022-04-22
Anticipated expiration: 2039-10-14
Also published as: CN110625135A

Abstract

Translated fromChinese

本发明公开了一种高效简易合成不同形貌Ru纳米晶的方法，将水合三氯化钌和聚乙烯吡咯烷酮（PVP）溶解在去离子水中搅拌混合，得到的混合溶液加入一定量的溴化钾或碘化钾固体，搅拌混合均匀后再加入甲醛溶液，所得到的混合液室温下搅拌0.5 h，然后将上述溶液密封并置于180~200℃的烘箱中反应2 h。反应结束后自然冷却至室温，向所得黑色分散液中加入丙酮离心分离，所得黑色沉淀用去离子水/丙酮洗涤三次，最后分散在水和乙醇的混合溶液里超声使其均匀分散。本发明采用水热法，利用卤素离子作为小分子调控剂，控制合成了不同形貌的钌纳米晶。本发明所得到的钌纳米晶可作为电解水的阴极材料，表现出了良好的产氢性能。

The invention discloses an efficient and simple method for synthesizing Ru nanocrystals with different shapes. The hydrated ruthenium trichloride and polyvinylpyrrolidone (PVP) are dissolved in deionized water and stirred and mixed, and a certain amount of potassium bromide is added to the obtained mixed solution. or potassium iodide solid, stir and mix evenly, then add formaldehyde solution, the resulting mixture is stirred at room temperature for 0.5 h, then the above solution is sealed and placed in an oven at 180-200 °C for 2 h. After the reaction, it was naturally cooled to room temperature, and acetone was added to the obtained black dispersion for centrifugation. The obtained black precipitate was washed three times with deionized water/acetone, and finally dispersed in a mixed solution of water and ethanol to make it uniformly dispersed. The present invention adopts the hydrothermal method and utilizes halide ions as small molecule regulators to control and synthesize ruthenium nanocrystals with different shapes. The ruthenium nanocrystals obtained by the invention can be used as cathode materials for electrolysis of water, and show good hydrogen production performance.

Description

Translated fromChinese

一种高效简易合成不同形貌Ru纳米晶的方法A simple and efficient method for the synthesis of Ru nanocrystals with different morphologies

技术领域technical field

本发明属于光电功能材料技术领域，涉及电催化材料，具体涉及一种高效简易合成不同形貌Ru纳米晶的方法。The invention belongs to the technical field of photoelectric functional materials, relates to electrocatalytic materials, and in particular relates to an efficient and simple method for synthesizing Ru nanocrystals with different shapes.

背景技术Background technique

能源和环境问题是当今时代备受关注的焦点。探索可再生、零污染的新型能源势在必行，最具代表性的新能源包括太阳能、风能、氢能源等。目前，利用电解水的方式制氢受到了世界范围内越来越多的研究者的重视。其中，在电催化制氢技术领域，催化剂Ru纳米晶由于具有价格低廉、过电位低、电流密度高和稳定性好等因素被应用于电解水的阴极材料。为了提高电催化制氢的效率，通常对合成的电催化材料提出了更多的要求。Energy and environmental issues are the focus of attention in today's era. It is imperative to explore renewable and zero-pollution new energy sources. The most representative new energy sources include solar energy, wind energy, and hydrogen energy. At present, hydrogen production by electrolysis of water has received more and more attention from researchers around the world. Among them, in the technical field of electrocatalytic hydrogen production, catalyst Ru nanocrystals have been used as cathode materials for water electrolysis due to their low price, low overpotential, high current density and good stability. To improve the efficiency of electrocatalytic hydrogen production, more requirements are generally placed on the synthesized electrocatalytic materials.

阴极电催化剂是电解水制氢体系的关键材料，影响电催化产氢的效率。目前在碱性电解液中可以与商业Pt/C催化剂相媲美的是钌基纳米材料，尽管钌基纳米材料是一种具有优异性能和稳定性的电解水阴极材料，但是暴露不同晶面、不同形貌的钌纳米晶具有不同的活性表现，对其进行可控合成是研究的方向。针对这一问题，可以采用小分子调控，利用其与钌表面的络合作用，控制钌晶核的形成和生长，从而控制其形貌。纳米材料形貌的可控合成是难点，在目前已有的报道中，无论在水相或是多元醇中合成所得的钌（Ru）纳米晶均为无规则形貌的纳米多面体小颗粒，对其形貌的可控合成，仍需更为深入的探索。Cathode electrocatalyst is the key material in the hydrogen production system of water electrolysis, which affects the efficiency of electrocatalytic hydrogen production. Currently, ruthenium-based nanomaterials are comparable to commercial Pt/C catalysts in alkaline electrolytes. Although ruthenium-based nanomaterials are a cathode material for water electrolysis with excellent performance and stability, they are exposed to different crystal planes and different Ruthenium nanocrystals with different morphology have different activity performance, and controllable synthesis of them is the research direction. In response to this problem, small molecule regulation can be used to control the formation and growth of ruthenium nuclei by using its complexation with the surface of ruthenium, thereby controlling its morphology. The controllable synthesis of nanomaterial morphology is difficult. In the existing reports, the ruthenium (Ru) nanocrystals synthesized in the aqueous phase or in polyols are all nano-polyhedral small particles with irregular morphology, which are not suitable for the synthesis of nanomaterials. The controllable synthesis of its morphology still needs to be further explored.

发明内容SUMMARY OF THE INVENTION

针对现有技术中存在的问题，本发明提供一种具有良好水/乙醇相分散性、形貌均一可控的，且具有良好的电催化性能的钌纳米晶及其制备方法。In view of the problems existing in the prior art, the present invention provides a ruthenium nanocrystal with good water/ethanol phase dispersibility, uniform and controllable morphology, and good electrocatalytic performance and a preparation method thereof.

为解决上述技术问题，本发明采用以下技术方案：In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions:

一种高效简易合成不同形貌Ru纳米晶的方法：将一定量的水合三氯化钌和聚乙烯吡咯烷酮（PVP）溶解在去离子水中搅拌混合，得到的混合溶液加入一定量的溴化钾或碘化钾固体，搅拌混合均匀后再加入甲醛溶液，所得到的混合液室温下搅拌0.5 h，然后将上述溶液转移到25 mL含聚四氟乙烯内衬的不锈钢反应釜中，密封并置于180~200℃的烘箱中反应2 h。反应结束后自然冷却至室温，向所得黑色分散液中加入丙酮离心分离，所得黑色沉淀用去离子水/丙酮洗涤三次，最后分散在水和乙醇的混合溶液里超声使其均匀分散。具体步骤如下：An efficient and simple method for synthesizing Ru nanocrystals with different morphologies: a certain amount of hydrated ruthenium trichloride and polyvinylpyrrolidone (PVP) are dissolved in deionized water, stirred and mixed, and the obtained mixed solution is added with a certain amount of potassium bromide or Potassium iodide solid, stir and mix evenly, then add formaldehyde solution, the obtained mixed solution is stirred at room temperature for 0.5 h, then the above solution is transferred to a 25 mL stainless steel reaction kettle containing PTFE lining, sealed and placed at 180~ The reaction was carried out in an oven at 200 °C for 2 h. After the reaction, it was naturally cooled to room temperature, and acetone was added to the obtained black dispersion for centrifugation. The obtained black precipitate was washed three times with deionized water/acetone, and finally dispersed in a mixed solution of water and ethanol to make it uniformly dispersed. Specific steps are as follows:

（1）将水合三氯化钌和聚乙烯吡咯烷酮（PVP）溶解在去离子水中，搅拌得到混合溶液；(1) Dissolve ruthenium trichloride hydrate and polyvinylpyrrolidone (PVP) in deionized water, and stir to obtain a mixed solution;

（2）加入一定量的溴化钾或者碘化钾于步骤（1）的混合溶液中；(2) adding a certain amount of potassium bromide or potassium iodide in the mixed solution of step (1);

（3）加入一定量的甲醛于步骤（2）得到的混合液中，搅拌0.5 h；(3) adding a certain amount of formaldehyde to the mixed solution obtained in step (2), stirring for 0.5 h;

（4）高温水热反应2 h；(4) High temperature hydrothermal reaction for 2 h;

（5）步骤（4）所得黑色沉淀用去离子水/丙酮洗涤三次，最后通过超声使其均匀分散在水和乙醇的混合溶液里。(5) The black precipitate obtained in step (4) was washed three times with deionized water/acetone, and finally uniformly dispersed in a mixed solution of water and ethanol by ultrasonication.

进一步，所述步骤（1）中，水合三氯化钌的用量为0.06 mmol，PVP的用量为100 mg，去离子水的用量为13 mL。Further, in the step (1), the amount of hydrated ruthenium trichloride is 0.06 mmol, the amount of PVP is 100 mg, and the amount of deionized water is 13 mL.

进一步，所述步骤（2）中，溴化钾的用量为3 mmol，碘化钾的用量为0.1 mmol。Further, in the step (2), the dosage of potassium bromide is 3 mmol, and the dosage of potassium iodide is 0.1 mmol.

进一步，所述步骤（3）中，甲醛的用量为0.4 mL。Further, in the step (3), the amount of formaldehyde used is 0.4 mL.

进一步，所述步骤（4）中，反应温度为180~200℃。Further, in the step (4), the reaction temperature is 180-200°C.

本发明的有益效果：本发明采用水热法，利用卤素离子作为小分子调控剂，控制合成了不同形貌的钌纳米晶。其中卤素离子和还原剂甲醛溶液具有特定的投入量，利用卤素离子与金属某一晶面的配位作用，控制钌晶核的形成和长大。最终得到了不同形貌、分散均匀的钌纳米晶。本发明所得到的钌纳米晶可作为电解水的阴极材料，表现出了良好的产氢性能。Beneficial effects of the present invention: the present invention adopts a hydrothermal method, and uses halide ions as small molecule regulators to control and synthesize ruthenium nanocrystals with different shapes. The halide ion and the reducing agent formaldehyde solution have a specific input amount, and the formation and growth of the ruthenium crystal nucleus are controlled by the coordination of the halide ion and a certain crystal plane of the metal. Finally, ruthenium nanocrystals with different morphologies and uniform dispersion were obtained. The ruthenium nanocrystals obtained by the invention can be used as cathode materials for electrolysis of water, and show good hydrogen production performance.

本发明所制备的钌纳米片和纳米颗粒，可作为电催化产氢材料使用，在1 M的KOH电解液中，10 mA cm^-2的电流密度下的过电势分别为67和29 mV，Tafel斜率分别为104和37mV dec^-1。The ruthenium^nanosheets and nanoparticles prepared by the invention can be used as electrocatalytic hydrogen production materials. The slopes are 104 and 37mV dec^-1 , respectively.

附图说明Description of drawings

图1为本发明钌纳米晶的XRD图；Fig. 1 is the XRD pattern of ruthenium nanocrystal of the present invention;

图2为本发明钌纳米晶的TEM图；Fig. 2 is the TEM image of ruthenium nanocrystal of the present invention;

图3为本发明钌纳米晶在1 M的KOH电解液中的电解水产氢LSV曲线和Tafel曲线。Fig. 3 is the LSV curve and the Tafel curve of the electrolysis of water for hydrogen production of the ruthenium nanocrystals of the present invention in 1 M KOH electrolyte.

具体实施方式Detailed ways

下面结合具体实施例，对本发明做进一步说明。应理解，以下实施例仅用于说明本发明而非用于限制本发明的范围，该领域的技术熟练人员可以根据上述发明的内容作出一些非本质的改进和调整。The present invention will be further described below with reference to specific embodiments. It should be understood that the following examples are only used to illustrate the present invention rather than to limit the scope of the present invention, and those skilled in the art can make some non-essential improvements and adjustments according to the content of the above invention.

实施例1Example 1

一种高效简易合成Ru纳米片（Ru-1）的方法，其步骤如下：An efficient and simple method for synthesizing Ru nanosheets (Ru-1), the steps are as follows:

（1）将0.06 mmol水合三氯化钌和100 mg聚乙烯吡咯烷酮（PVP，24000）溶解在13mL去离子水中，搅拌得到混合溶液；(1) Dissolve 0.06 mmol of hydrated ruthenium trichloride and 100 mg of polyvinylpyrrolidone (PVP, 24000) in 13 mL of deionized water, and stir to obtain a mixed solution;

（2）加入3 mmol溴化钾于上述混合溶液中；(2) Add 3 mmol potassium bromide to the above mixed solution;

（3）加入0.4 mL的甲醛溶液于上述混合液中，将所得混合溶液搅拌0.5 h；(3) Add 0.4 mL of formaldehyde solution to the above mixed solution, and stir the obtained mixed solution for 0.5 h;

（4）180℃高温水热反应2 h；(4) 180 ℃ high temperature hydrothermal reaction for 2 h;

（5）所得黑色沉淀用去离子水/丙酮洗涤三次，最后通过超声使其均匀分散在水和乙醇的混合溶液里。(5) The obtained black precipitate was washed three times with deionized water/acetone, and finally dispersed uniformly in a mixed solution of water and ethanol by ultrasonication.

实施例2Example 2

一种高效简易合成Ru纳米颗粒（Ru-2）的方法，其步骤如下：An efficient and simple method for synthesizing Ru nanoparticles (Ru-2), the steps are as follows:

（2）加入0.1 mmol的碘化钾于上述混合溶液中；(2) Add 0.1 mmol of potassium iodide to the above mixed solution;

（3）加入0.4 mL甲醛溶液于上述混合液中，将所得混合溶液搅拌0.5 h；(3) Add 0.4 mL of formaldehyde solution to the above mixed solution, and stir the obtained mixed solution for 0.5 h;

（4）200℃高温水热反应2 h；(4) 200 ℃ high temperature hydrothermal reaction for 2 h;

（5）所得黑色沉淀用去离子水/丙酮洗涤三次，最后通过超声使其均匀分散在水和乙醇的混合溶液里。(5) The obtained black precipitate was washed three times with deionized water/acetone, and finally uniformly dispersed in a mixed solution of water and ethanol by ultrasonication.

如图1所示，X射线粉末衍射表明，所制得的钌纳米晶物相均为hcp相。对应JCPDS卡片编号06-0663，无杂质峰出现，说明产品纯度较高。As shown in Fig. 1, X-ray powder diffraction shows that the obtained ruthenium nanocrystals are allhcp phases. Corresponding to JCPDS card number 06-0663, there is no impurity peak, indicating that the product has high purity.

如图2所示，透射电镜图显示以溴化钾作为小分子调控剂时得到了形貌为纳米片结构的钌纳米晶，而以碘化钾为小分子调控剂时得到的是钌纳米颗粒。将本实施例所制备的钌纳米片和纳米颗粒用作电解水产氢材料，测试其电催化性能，具体方法如下：先将水和乙醇的混合Ru纳米晶分散液进行ICP-OES定量，再取相同质量的钌纳米晶分散液稀释至1mL（水和乙醇的体积比为3:7的混合溶剂稀释），加入30 μLNafion（5 wt.%）溶液，超声约1 h使其分散均匀，取5μL分散液滴在3 mm玻碳电极上自然干燥，以此为工作电极。电化学析氢测试采用三电极体系，以Ag/AgCl（饱和氯化钾）为参比电极，石墨棒为对电极。析氢反应极化曲线由线性扫描伏安法（Linear sweep voltammetry，LSV）测试得到，电位测试范围为-0.9~-1.5 V（vs. Ag/AgCl）,扫描速度为5 mV/s。电位值按照能斯特方程拟合为相对于可逆氢电极（Reversible hydrogen electrode，RHE）电位。As shown in Figure 2, the transmission electron microscope image shows that when potassium bromide is used as a small molecule regulator, ruthenium nanocrystals with a nanosheet structure are obtained, and when potassium iodide is used as a small molecule regulator, ruthenium nanoparticles are obtained. The ruthenium nanosheets and nanoparticles prepared in this example were used as materials for electrolysis of water for hydrogen production, and their electrocatalytic performance was tested. The same mass of ruthenium nanocrystal dispersion was diluted to 1 mL (a mixed solvent with a volume ratio of water and ethanol of 3:7), 30 μL of Nafion (5 wt.%) solution was added, and sonicated for about 1 h to make it uniformly dispersed. Take 5 μL The dispersed droplets were naturally dried on a 3 mm glassy carbon electrode, which was used as the working electrode. The electrochemical hydrogen evolution test adopts a three-electrode system, with Ag/AgCl (saturated potassium chloride) as the reference electrode and a graphite rod as the counter electrode. The polarization curve of hydrogen evolution reaction was obtained by linear sweep voltammetry (LSV) test, the potential test range was -0.9~-1.5 V (vs. Ag/AgCl), and the scanning speed was 5 mV/s. The potential values were fitted to the potential relative to the reversible hydrogen electrode (RHE) according to the Nernst equation.

E_RHE =E_Ag/AgCl + 0.059×pH +E^θ_Ag/AgCl (0.197)E_RHE =E_Ag/AgCl + 0.059×pH +E^θ_Ag/AgCl (0.197)

如图3所示，在1 M的KOH电解液中，本实施例所制备的钌纳米片和纳米颗粒的LSV曲线和Tafel曲线，图3显示在10 mA cm^-2的电流密度下的过电势分别为67和29 mV，Tafel斜率分别为104和37 mV dec^-1.As shown in Figure 3, the LSV curve and Tafel curve of the ruthenium nanosheets and nanoparticles prepared in this example in 1 M KOH electrolyte, and Figure 3 shows the overpotential at a current density of 10 mA cm^-2 are 67 and 29 mV, respectively, and the Tafel slopes are 104 and 37 mV dec^-1 .

以上显示和描述了本发明的基本原理和主要特征以及本发明的优点。本行业的技术人员应该了解，本发明不受上述实施例的限制，上述实施例和说明书中描述的只是说明本发明的原理，在不脱离本发明精神和范围的前提下，本发明还会有各种变化和改进，这些变化和改进都落入要求保护的本发明范围内。本发明要求保护范围由所附的权利要求书及其等效物界定。The foregoing has shown and described the basic principles and main features of the present invention, as well as the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions only illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have Various changes and modifications fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for efficiently, simply and easily synthesizing Ru nanocrystals with different morphologies is characterized by comprising the following steps:

(1) dissolving 0.06 mmol of ruthenium trichloride hydrate and 100 mg of polyvinylpyrrolidone (PVP) in 13mL of deionized water, and stirring to obtain a mixed solution;

(2) adding 3 mmol of potassium bromide or 0.1 mmol of potassium iodide into the mixed solution in the step (1);

(3) adding 0.4 mL of formaldehyde into the mixed solution obtained in the step (2), and stirring for 0.5 h;

(4) carrying out hydrothermal reaction for 2 hours at 180-200 ℃;

(5) washing the black precipitate obtained in the step (4) with deionized water/acetone for three times, and finally uniformly dispersing the black precipitate in a mixed solution of water and ethanol by ultrasonic;

the obtained Ru nanocrystal phases are allhcpPhase (1);

when 3 mmol of potassium bromide is added, Ru nanosheets are obtained, and the Ru nanosheets are 10 mA cm in 1M KOH electrolyte^-2The overpotential at the current density of (1) is 67 mV, and the Tafel slope is 104 mV dec^-1；

When 0.1 mmol of potassium iodide is added, Ru nanoparticles are obtained, and the Ru nanoparticles are dissolved in a KOH electrolyte solution of 1M at 10 mA cm^-2The overpotential at the current density of (1) is 29 mV, and the Tafel slope is 37 mV dec^-1。