Porous Pt / Ru / RuO2 heterostructure metal aerogel material for electro-catalysis and preparation method of porous Pt / Ru / RuO2 heterostructure metal aerogel material

Abstract

The invention relates to a Pt / Ru / RuO2 heterostructure metal aerogel material and a preparation method thereof. The method is realized through a two-step simple process which comprises the following steps: firstly, reducing ruthenium trichloride and potassium chloroplatinate in an aqueous solution by taking sodium borohydride as a reducing agent to obtain precursor hydrogel; and then the hydrogel is subjected to freeze drying and annealing treatment, and the final product Pt / Ru / RuO2 heterostructure metal aerogel is obtained. According to the preparation strategy, a traditional sodium borohydride reduction method is improved, operation is easy and convenient, consumed time is short, and used drugs are not only non-toxic and harmless, but also extremely low in cost. Performance tests show that the Pt / Ru / RuO2 heterostructure metal aerogel has excellent performance in electro-catalytic hydrogen evolution (HER) and oxygen evolution (OER) reactions: under the high current density of 10 mA. Cm <-2 >, the overpotentials of HER and OER are only 17 mV and 1840 mV respectively; more notably, after continuous testing for 24 hours under the current density, the performance of the material is basically not attenuated, and excellent stability is shown. By virtue of the advantages, the material has a wide application prospect in the field of energy conversion of electrolyzed water and the like.

Description

Technical Field

[0001] The invention relates to a metal aerogel material with a porous Pt / Ru / RuO2 heterostructure for electrocatalysis and a preparation method thereof, belonging to the field of nanomaterials. Background Art

[0002] With the rapid development of society and economy, global energy demand continues to grow, and the depletion of traditional fossil energy and the resulting environmental problems are becoming increasingly severe. The development and utilization of clean energy such as hydrogen and wind energy have become important directions for solving the energy crisis and achieving sustainable development. Among them, electrochemical water splitting technology is regarded as one of the key pathways for large-scale hydrogen production due to its high efficiency and environmentally friendly characteristics. However, the two core half-reactions involved in the water splitting process—the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER)—both suffer from slow kinetics and high overpotentials. In particular, the OER, due to its complex four-electron transfer process, has become a bottleneck restricting overall efficiency. In addition, traditional electrolysis systems usually require the use of an anodic OER catalyst and a cathode HER catalyst, which increases the complexity and cost of the equipment. Therefore, the development of bifunctional electrocatalysts with both efficient HER and OER activity has become a research hotspot in recent years.

[0003] Aerometallic materials, owing to their unique chemical and physical properties (large surface area, high conductivity, and porosity) and simple synthesis methods, have shown great potential for application in catalysis. To further expand the diversity of aerometallic materials, the design and development of alternative forms of aerometallic materials is essential. Interface engineering is an effective strategy to enhance the electrocatalytic activity of hybrid nanomaterials through the synergistic effects of dual or even multiple active sites. Different active components may favor different reaction steps. Rational tuning of heterostructures can enable these individual processes to occur at different locations in close proximity, thereby accelerating the overall reaction kinetics. Furthermore, this coupling effect can effectively modulate the electronic state of the electrocatalyst. Given these advantages, the design of heterostructured aerometallic materials has great potential as efficient electrocatalytic materials. However, due to the specificity of aerometallic preparation methods, no work has been reported on aerometallic materials with heterojunction structures. Summary of the Invention

[0004] The present invention provides a method for preparing a porous Pt / Ru / RuO2 heterostructure metal aerogel material. By regulating the constituent structural units and surface electronic structure of the metal aerogel, the metal aerogel is endowed with excellent performance, and can be used as a long-term and efficient bifunctional electrocatalyst.

[0005] One of the purposes of the present invention is to provide a novel porous material.

[0006] A second object of the present invention is to provide a highly efficient bifunctional electrocatalyst.

[0007] The Pt / Ru / RuO2 heterostructured aerogel material prepared in the present invention is synthesized by a modified in-situ spontaneous gelation method using a one-step NaBH4 reduction method to synthesize RuPt hydrogel. The RuPt aerogel is obtained after freeze-drying. The Pt / Ru / RuO2 heterostructured aerogel material is prepared using a controlled air oxidation method. The preparation process includes the following specific steps: 1. First, dissolve 0.01-0.015 g of ruthenium chloride trihydrate and 0-0.003 g of potassium chloroplatinate in 2 mL of aqueous solution and sonicate for 2 h to obtain a transparent solution. 2. Prepare 0.5 mL of 0.3 M sodium borohydride solution and add it dropwise to the solution obtained in step 1. Stir for 5 minutes and then let it stand for 6 hours. Wash the resulting product with water 5 times to obtain a hydrogel. 3. Freeze-dry the hydrogel obtained in step 2 for 12 h to obtain a black solid; 4. The black solid obtained in step 3 was placed in a crucible with a lid and calcined in a muffle furnace at 250-450°C for 0.5 h to obtain a metal aerogel with a Pt / Ru / RuO2 heterostructure.

[0008] Beneficial effects of the present invention: 1. The present invention provides a Pt / Ru / RuO2 heterostructured metal aerogel material for electrocatalysis and a preparation method thereof. The aerogel material is prepared by a NaBH4 reduction method and requires only common laboratory equipment, without the need for specialized equipment. The process is simple and easy to operate. 2. The drugs used in the present invention are non-toxic, harmless, inexpensive, simple to prepare, and take a short time. No complicated steps are required after preparation, making them particularly suitable for batch and low-cost preparation, and suitable for industrial-scale production and commercial application. 3. The Pt / Ru / RuO2 heterostructured metal aerogel prepared by this method showed excellent performance in HER and OER tests: when the current density reached 100 mA·cm -2 When the overpotentials of HER and OER are only 17 mV and 184 mV respectively, the overpotentials of HER and OER are only 17 mV and 184 mV respectively. -2 At a current density of 1.5 GHz, the material can operate stably for 12 h without performance degradation. 4. The Pt / Ru / RuO2 heterostructured metal aerogel material provided by the present invention has been successfully applied in the field of water electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction to the drawings will be given below in the description of the embodiments or the prior art. However, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0010] Figure 1 Flow chart for preparing Pt / Ru / RuO2 metal aerogel material for Example 1.

[0011] Figure 2 a is a scanning electron microscope image of the material prepared in Example 1. Figure 2 a is a scanning electron microscope image of the RuPt metal aerogel prepared in Example 1, Figure 2 b is a scanning electron microscope image of the Pt / Ru / RuO2 metal aerogel prepared in Example 1.

[0012] Figure 3 This is a high-resolution transmission electron microscope image of the material prepared in Example 1 of the invention.

[0013] Figure 4 This is the X-ray diffraction pattern of the material prepared in Example 1 of the present invention.

[0014] Figure 5 This is the elemental analysis image of the material prepared in Example 1 of the present invention. Figure 5 a is the signal of three elements, Figure 5 b is the signal of platinum element, Figure 5 c is the signal of ruthenium, Figure 5 d is the signal of oxygen element.

[0015] Figure 6 This is a graph showing the electrocatalytic hydrogen evolution performance of the materials of Example 1 of the present invention and Comparative Examples 1 and 2 in 1 M KOH. Figure 6 a is the linear sweep voltammetry test diagram, Figure 6 b is the chronoamperometry test diagram.

[0016] Figure 7 This is a graph showing the electrocatalytic oxygen evolution performance of the materials of Example 1 of the present invention and Comparative Examples 1 and 2 in 1M KOH. Figure 7 a is the linear sweep voltammetry test diagram, Figure 7 b is the chronoamperometry test diagram. Specific implementation methods

[0017] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0019] Unless otherwise specified, the experimental methods described in the following examples are all conventional methods; the reagents and materials described are all commercially available unless otherwise specified.

[0020] Example 1: First, 0.012 g of ruthenium chloride trihydrate and 0.002 g of potassium chloroplatinate were added to 2 mL of aqueous solution and stirred for 2 h to obtain a transparent solution. Under stirring conditions, 0.5 mL of 0.3 M sodium borohydride solution was added to the obtained transparent solution, stirred, and then allowed to stand for 6 h to obtain a black RuPt hydrogel. The hydrogel was washed with water five times and then freeze-dried for 12 h to obtain a black solid. The black solid was placed in a covered crucible and calcined at 350°C in a muffle furnace for 0.5 h to obtain a Pt / Ru / RuO2 metal aerogel material, named Pt / Ru / RuO2Aerogel-350.

[0021] Example 2: First, 0.012 g of ruthenium chloride trihydrate and 0.001 g of potassium chloroplatinate were added to 2 mL of aqueous solution and stirred for 2 h to obtain a transparent solution. Under stirring conditions, 0.5 mL of 0.3 M sodium borohydride solution was added to the obtained transparent solution, stirred, and allowed to stand for 6 h to obtain a black RuPt hydrogel. The hydrogel was washed with water five times and then freeze-dried for 12 h to obtain a black solid. The black solid was placed in a covered crucible and calcined at 350°C in a muffle furnace for 0.5 h to obtain a Pt / Ru / RuO2 metal aerogel material.

[0022] Example 3: First, 0.014 g of ruthenium chloride trihydrate and 0.002 g of potassium chloroplatinate were added to 2 mL of aqueous solution and stirred for 2 h to obtain a transparent solution. Under stirring conditions, 0.5 mL of 0.3 M sodium borohydride solution was added to the obtained transparent solution, stirred, and then allowed to stand for 6 h to obtain a black RuPt hydrogel. The hydrogel was washed with water five times and then freeze-dried for 12 h to obtain a black solid. The black solid was placed in a covered crucible and calcined at 350°C in a muffle furnace for 0.5 h to obtain a Pt / Ru / RuO2 metal aerogel material.

[0023] Comparative Example 1: First, 0.012 g of ruthenium chloride trihydrate and 0.002 g of potassium chloroplatinate were added to 2 mL of aqueous solution and stirred for 2 h to obtain a transparent solution. Under stirring conditions, 0.5 mL of 0.3 M sodium borohydride solution was added to the obtained transparent solution, stirred, and then allowed to stand for 6 h to obtain a black RuPt hydrogel. The hydrogel was washed with water five times and then freeze-dried for 12 h to obtain a black solid. The black solid was placed in a covered crucible and calcined at 250°C in a muffle furnace for 0.5 h to obtain a Pt / Ru / RuO2 heterostructured metal aerogel material, named Pt / Ru / RuO2Aerogel-250.

[0024] Comparative Example 2: First, 0.012 g of ruthenium chloride trihydrate and 0.002 g of potassium chloroplatinate were added to 2 mL of aqueous solution and stirred for 2 h to obtain a transparent solution. Under stirring conditions, 0.5 mL of 0.3 M sodium borohydride solution was added to the obtained transparent solution, stirred, and then allowed to stand for 6 h to obtain a black RuPt hydrogel. The hydrogel was washed with water five times and then freeze-dried for 12 h to obtain a black solid. The black solid was placed in a covered crucible and calcined at 450°C in a muffle furnace for 0.5 h to obtain a Pt / Ru / RuO2 heterostructured metal aerogel material, named Pt / Ru / RuO2Aerogel-450.

[0025] Figure 1 Schematic diagram of the preparation of the Pt / Ru / RuO2 metal aerogel. At room temperature, a RuPt alloy hydrogel was synthesized after 2 hours of direct in situ reduction of an aqueous solution of metal salts using NaBH4. Further purification and freeze-drying resulted in the RuPt metal aerogel. Subsequently, the Pt / Ru / RuO2 metal aerogel was obtained by heating the hydrogel in a muffle furnace at 350°C for 0.5 hours.

[0026] Figure 2 a is a SEM image of the RuPt metal aerogel prepared in Inventive Example 1, Figure 2 b is an SEM image of the Pt / Ru / RuO2 metal aerogel prepared in Inventive Example 1. Both images show that the resulting aerogel exhibits a three-dimensional porous structure composed of interconnected nanoparticles, which are randomly fused at different angles to form a network structure. Furthermore, the aerogel structure is well maintained after oxidation treatment.

[0027] Figure 3 This is a high-resolution transmission electron microscope (HRTEM) image of the material prepared in Example 1 of the invention. Figure 3 Lattice fringes corresponding to the (111) crystal plane of Ru and the (101) crystal plane of RuO2 can be found, proving the heterogeneous structure of the sample.

[0028] Figure 4 The X-ray diffraction (XRD) pattern of the Pt / Ru / RuO2 heterostructured metal aerogel electrocatalyst prepared in Example 1 of the present invention. Figure 2 It can be seen that the strongest XRD diffraction peak at 2θ = 44° corresponds to the elemental Ru (101) crystal plane. In addition, the XRD diffraction peak corresponding to the RuO2 (110) crystal plane was observed in the XRD spectrum, further reflecting that the RuO2 component was generated in situ in the partially oxidized Ru aerogel sample.

[0029] Figure 5 Element mapping image of the metal aerogel material with Pt / Ru / RuO2 heterostructure prepared in Example 1 of the present invention. Figure 5 It can be seen that the Ru, Pt and O elements are evenly distributed.

[0030] Figure 6 This is a graph showing the electrocatalytic hydrogen evolution performance of the materials of Example 1 of the present invention and Comparative Examples 1 and 2 in 1 M KOH. Figure 6 a is the linear sweep voltammetry test diagram, Figure 6 b is the test diagram of the chronoamperometry. Figure 6 It can be seen that the prepared product only needs an overpotential of 17mV to reach 10 mA·cm -2 The current density indicates that some Pt / Ru / RuO2 heterostructured metal aerogel materials have excellent hydrogen evolution performance, and it also proves that 350℃ is the optimal heat treatment temperature. Figure 6 b shows that after 24 h of continuous testing, the current density hardly decays, indicating its excellent stability.

[0031] Figure 7 This is a graph showing the electrocatalytic oxygen evolution performance of the materials of Example 1 of the present invention and Comparative Examples 1 and 2 in 1M KOH. Figure 7 a is the linear sweep voltammetry test diagram, Figure 7 b is the test diagram of the chronoamperometry. Figure 7 It can be seen that the prepared product only needs an overpotential of 184 mV to reach 10 mA·cm -2 The current density shows that the metal aerogel material with Pt / Ru / RuO2 heterostructure has excellent oxygen evolution performance. Figure 7 b shows that after 24 h of continuous testing, the current density hardly decays, indicating its excellent stability.

[0032] Obviously, those skilled in the art may make various modifications and variations to the Pt / Ru / RuO2 heterostructure aerometal material and its preparation method described herein without departing from the spirit and scope of the present invention. Thus, to the extent such modifications and variations fall within the scope of the claims and their equivalents, the present invention is intended to encompass such modifications and variations.

Claims

1. A method for preparing a porous Pt / Ru / RuO2 metal aerogel material, comprising the following steps: First, 0.01-0.015 g of ruthenium chloride trihydrate and 0-0.003 g of potassium chloroplatinate were dissolved in 2 mL of aqueous solution and sonicated for 2 hours to obtain a transparent solution. Under stirring conditions, 0.5 mL of freshly prepared 0.3 M sodium borohydride solution was added dropwise to the obtained transparent solution. After stirring for 5 minutes and then standing for 6 hours, the obtained product was washed with water 5 times to obtain a black RuPt hydrogel. The obtained hydrogel was freeze-dried for 12 hours to obtain a black solid. The black solid was placed in a covered crucible and calcined in a muffle furnace at 250-450°C for 0.5 hour to obtain a Pt / Ru / RuO2 heterostructured metal aerogel.

2. The method for preparing a Pt / Ru / RuO2 heterostructured metal aerogel material according to claim 1, characterized in that: The amount of ruthenium chloride trihydrate used was 0.012 g, and the amount of potassium chloroplatinate used was 0.002 g.

3. The method for preparing a Pt / Ru / RuO2 heterostructured metal aerogel material according to claim 1, characterized in that: The ratio of metal concentration to sodium borohydride concentration was 1:

3.

4. Application of the metal aerogel material of Pt / Ru / RuO2 heterostructure prepared by the preparation method according to claim 1, characterized in that: The Pt / Ru / RuO2 heterostructured metal aerogel material is applied to electrocatalytic water decomposition.

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