Process for the preparation of carbon-supported transition metal silicide composites and their electrocatalytic applications

Abstract

The application belongs to the field of electrocatalytic materials, and relates to a preparation method of a carbon-loaded transition metal silicide composite material and electrocatalytic application thereof. The preparation method comprises the following steps: mixing methyl silicone oil and a transition metal salt according to a mass ratio of (1-20):1, fully grinding for 10-120 min, high-temperature calcining the mixture obtained after grinding, heating to 700-1200 DEG C at a heating rate of 1-20 DEG C / min, and keeping at the temperature for 0.5-5 h, and then cooling to room temperature to obtain the carbon-loaded transition metal silicide composite material. The application can simultaneously realize the generation of a carbon carrier and a metal silicide, is beneficial to enhancing the interaction between the two, and thus improves the stability of the whole; the application does not generate by-products, does not need special treatment, has a short synthesis period, good repeatability, is easy to scale up, and the prepared composite material exhibits excellent catalytic performance in electrocatalytic application.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electrocatalytic materials, and particularly relates to a preparation method of a carbon-loaded transition metal silicide composite material and electrocatalytic application thereof. BACKGROUND

[0002] Transition metal silicides are a kind of inexpensive and abundant inorganic materials. Due to the interaction between silicon atoms and metals, the metal lattice is expanded and the metal bond length is increased, which makes the metal d band shrink and the state density near the Fermi level increase, thus having physical and chemical properties different from transition metals, such as high melting point, low resistance, high chemical stability, etc. In recent years, transition metal silicides have gradually attracted widespread attention as new catalytic materials. They exhibit unique properties in traditional selective hydrogenation, carbon monoxide methanation, hydrogenation dechlorination, hydrogenation desulfurization and other reactions, and have shown great potential in emerging photocatalysis and electrocatalysis fields. Scientists have reported many methods for preparing metal silicide composites, including arc melting, mechanical alloying, solid-state metathesis reaction, molten salt reaction technology, etc. However, most of these methods are complex, expensive and severely limited by the structure of the material itself.

[0003] Carbon-loaded catalysts not only can fully expose the active sites of the catalysts, but also can improve the stability of the catalysts. The carbon-loaded metal silicide catalysts reported in the literature often need to add additional carbon carriers such as carbon nanotubes, carbon spheres, carbon black, etc. This method often results in weak interaction between the metal silicide and the carbon carrier, which makes the stability of the metal silicide poor. In addition, the commonly used silicon source in the existing literature is solid powder such as silicon powder, which is difficult to mix uniformly with other metal precursors due to the characteristics of the solid powder. Methyl silicone oil or dimethyl silicone oil is a colorless transparent viscous liquid, which can be easily mixed with other metal precursors. Methyl silicone oil or dimethyl silicone oil can not only be used as a silicon source, but also as a carbon source. It is worth noting that there is no research on using methyl silicone oil or dimethyl silicone oil as a silicon source. SUMMARY

[0004] The present application aims to solve the above-mentioned problems in the prior art, and proposes a preparation method of a carbon-loaded transition metal silicide composite material and electrocatalytic application thereof. The method has the advantages of being convenient, fast and easy to mass-produce, and is a general method for simply and batch producing carbon-loaded transition metal silicide composites suitable for electrocatalytic applications.

[0005] The technical scheme of the present application is as follows:

[0006] The present application protects a preparation method of a carbon-loaded transition metal silicide composite material, which comprises the following steps:

[0007] The methyl silicone oil and the transition metal salt are mixed in a mass ratio of (1-20) : 1, and are sufficiently ground for 10-120 min; the mixture obtained after grinding is high-temperature calcined, and is heated to 700-1200 DEG C at a heating rate of 1-20 DEG C / min, and is kept at the temperature for 0.5-5 h, and then is cooled to room temperature, to obtain the carbon-loaded transition metal silicide composite material.

[0008] Further, the methyl silicone oil is replaced by dimethyl silicone oil.

[0009] Further, the methyl silicone oil and the transition metal salt are mixed in a mass ratio of 5:1, and are sufficiently ground for 30 min.

[0010] Further, the transition metal salt is any one of transition metal nitrate, transition metal chloride, transition metal carbonate or transition metal sulfate.

[0011] Further, the transition metal salt is any one of ruthenium chloride, iron nitrate or iridium trichloride.

[0012] Further, the temperature of high-temperature calcination is 1000 DEG C, and the temperature is raised to 1000 DEG C at a heating rate of 10 DEG C / min in a programmed heating mode, and is kept for 2 h.

[0013] Further, the mixture is high-temperature calcined in a nitrogen atmosphere.

[0014] Further, the nitrogen is replaced by argon, hydrogen, hydrogen / argon mixed gas or hydrogen / nitrogen mixed gas.

[0015] The application also protects the carbon-loaded transition metal silicide composite material prepared by the preparation method.

[0016] The application also protects the application of the carbon-loaded transition metal silicide composite material in electrocatalysis or preparation of electrocatalytic material.

[0017] The application has the following beneficial effects:

[0018] The application uses methyl silicone oil or dimethyl silicone oil as a silicon source, and obtains the carbon-loaded transition metal silicide composite material by simple grinding and calcination; the experimental process is that the methyl silicone oil or dimethyl silicone oil is mixed with the transition metal salt, and is calcined at a certain temperature, and the product is obtained after cooling to room temperature, without subsequent treatment.

[0019] The preparation method of the present application can realize the generation of carbon carrier and metal silicide synchronously, which is beneficial to enhance the interaction between the two, thereby improving the overall stability; the present application has no by-product generation, does not need special treatment, and has short synthesis cycle, good repeatability, and easy scale-up preparation. The composite material prepared by the method of the present application exhibits excellent catalytic performance in electrocatalytic application. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 X-ray diffraction pattern of carbon-supported ruthenium silicide / ruthenium composite material;

[0021] Figure 2 Raman pattern of carbon-supported ruthenium silicide / ruthenium composite material;

[0022] Figure 3 Transmission pattern of carbon-supported ruthenium silicide / ruthenium composite material;

[0023] Figure 4 Linear sweep voltammetry (LSV) curve of the electrocatalytic hydrogen evolution performance comparison of carbon-supported ruthenium silicide / ruthenium composite material and commercial benchmark 20wt% Pt / C;

[0024] Figure 5 X-ray diffraction pattern of the product of Comparative Example 1. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0026] In order to further understand the present application, the present application will be further described in combination with the drawings and embodiments.

[0027] Example 1

[0028] 500mg methyl silicone oil and 100mg ruthenium chloride were added into a crucible, and were ground thoroughly for 30 minutes. The obtained mixture after grinding was transferred into an alumina porcelain boat, and was placed in a tube furnace. The gas in the tube furnace was completely replaced by argon for 30 minutes. Then, the temperature was programmed to rise to 1000℃ at a rate of 10℃ / min, and was maintained for 2 hours. Then, the temperature was naturally cooled to room temperature to obtain a carbon-supported ruthenium silicide / ruthenium composite material.

[0029] Morphological characteristics of carbon-supported ruthenium silicide / ruthenium composite material in Test Example 1

[0030] X-ray diffraction (XRD) was performed on the carbon-supported ruthenium silicide / ruthenium composite material prepared in Example 1, and the results were as follows. Figure 1 The XRD pattern of the carbon-supported ruthenium silicide / ruthenium composite is shown. The X-ray diffraction pattern includes characteristic peaks of ruthenium silicide (RuSi) and ruthenium (Ru). Due to the high intensity of the characteristic peaks in the metal-based material, the characteristic peaks of carbon are masked. To confirm the presence of carbon in the prepared material, we further performed Raman characterization tests.

[0031] like Figure 2 The image shows the Raman spectrum of carbon-supported ruthenium silicide / ruthenium composite material. The Raman spectrum shows obvious defect peaks (D) and graphite peaks (G), indicating that carbon materials are indeed present in the material.

[0032] Figure 3 The image shows a transmission spectrum of carbon-supported ruthenium silicide / ruthenium composite material. The transmission spectrum shows the characteristic lattice fringes of carbon (C), ruthenium silicide (RuSi), and ruthenium (Ru). Moreover, the structure shows that the prepared material exists in the form of a heterojunction structure of carbon-supported ruthenium silicide / ruthenium composite material.

[0033] Experimental Example 2: Electrochemical Performance Testing of Carbon-Supported Ruthenium Silicate / Ruthenium Composite Material

[0034] Formulation of carbon-supported ruthenium silicide / ruthenium composite catalyst ink:

[0035] (1) Weigh 2 mg of the carbon-supported ruthenium silicide / ruthenium composite catalyst prepared in Example 1, disperse it in 300 μL of anhydrous ethanol and 40 μL of Nafion solution with a mass fraction of 5 wt%, and sonicate for 1 h to obtain a uniformly dispersed catalyst ink.

[0036] (2) Electrochemical tests were conducted on a CHI 760E electrochemical workstation (CHI Instruments, China) using a three-electrode system; the carbon rod electrode and the reversible hydrogen electrode served as the counter electrode and the reference electrode, respectively.

[0037] Preparation of the working electrode:

[0038] 6 μL of catalyst ink was pipetted onto a 3 mm diameter glassy carbon electrode and allowed to air dry at room temperature. At this point, the catalyst loading on the glassy carbon electrode was 0.5 mg cm⁻¹. -2 During the electrocatalytic hydrogen evolution test, the linear voltammetry curve scan rate was 5 mV / s. -1 The data were 95% IR compensated. The electrolyte was 1M KOH. The catalyst was tested at 10 mA cm⁻¹. -2 When calculating the time-potential curve under constant current density, a glassy carbon electrode coated with catalyst was used as the working electrode, a carbon rod as the counter electrode, and a reversible hydrogen electrode as the reference electrode.

[0039] Catalyst electrochemical performance test results:

[0040] Figure 4 The electrocatalytic hydrogen evolution performance of carbon-supported ruthenium silicide / ruthenium composite material (Ru / RuSi) is shown in comparison with commercial benchmark 20wt% Pt / C. From Figure 4 The linear sweep voltammetry (LSV) curve on the left shows that the benchmark current density of 10 mA cm-2 -2 The overpotential of the ruthenium silicide / ruthenium composite material is only 27 mV, which is better than that of the commercial benchmark 20wt% Pt / C (37 mV). From Figure 4 The linear sweep voltammetry (LSV) curve on the right shows that the mass activity (9496 mA mg -1 ) of the ruthenium silicide / ruthenium composite material is 17.5 times that of the commercial benchmark 20wt% Pt / C (543 mA mg -1 ), indicating that the prepared composite material has excellent electrocatalytic activity.

[0041] Example 2

[0042] 500 mg of methyl silicone oil and 100 mg of iron nitrate were weighed into a crucible and ground thoroughly for 30 minutes; then the mixture obtained after grinding was transferred to an alumina porcelain boat and placed in a tube furnace, argon was passed for 30 minutes, the gas in the tube furnace was completely replaced with argon, and then the temperature was programmed to rise to 1000°C at a rate of 10°C / min, maintained for 2 hours, and then naturally cooled to room temperature to obtain a carbon-supported iron silicide / iron composite material.

[0043] Example 3

[0044] 500 mg of methyl silicone oil and 100 mg of iridium trichloride were weighed into a crucible and ground thoroughly for 30 minutes; then the mixture obtained after grinding was transferred to an alumina porcelain boat and placed in a tube furnace, argon was passed for 30 minutes, the gas in the tube furnace was completely replaced with argon, and then the temperature was programmed to rise to 1000°C at a rate of 10°C / min, maintained for 2 hours, and then naturally cooled to room temperature to obtain a carbon-supported iridium silicide / iridium composite material.

[0045] Example 4

[0046] 500 mg of methyl silicone oil and 500 mg of ruthenium chloride were weighed into a crucible and ground thoroughly for 10 minutes, the mixture obtained after grinding was transferred to an alumina porcelain boat and placed in a tube furnace, nitrogen was passed for 30 minutes, the gas in the tube furnace was completely replaced with argon, and then the temperature was programmed to rise to 700°C at a rate of 1°C / min, maintained for 0.5 hours, and then naturally cooled to room temperature to obtain a carbon-supported ruthenium silicide / ruthenium composite material.

[0047] Example 5

[0048] Add 2g of methyl silicone oil and 100mg of ruthenium chloride to a crucible and grind thoroughly for 120 minutes. Transfer the resulting mixture to an alumina ceramic boat and place it in a tube furnace. Purge with hydrogen for 30 minutes to completely replace the gas in the tube furnace with argon. Then, heat the mixture to 1200℃ at a rate of 20℃ / min and hold for 5 hours. Allow it to cool naturally to room temperature to obtain a carbon-supported ruthenium silicide / ruthenium composite material.

[0049] Comparative Example 1

[0050] The difference between Comparative Example 1 and Example 1 is that silicon powder is used instead of methyl silicone oil, while the other reaction reagents and reaction steps are the same as in Example 1.

[0051] The product prepared in Comparative Example 1 was subjected to X-ray diffraction to obtain the following results: Figure 5 The XRD pattern shown. From Figure 5 It can be seen that when silicon powder was used as the silicon source in Comparative Example 1, ruthenium silicide was not generated under the same conditions; only a mixture of silicon and ruthenium was generated.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, alterations, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing a carbon-supported transition metal silicide composite material for use in electrocatalysis or for producing an electrocatalytic material, characterized by, The method comprises the following steps: The methyl silicone oil and the transition metal salt are mixed in a mass ratio of (1-20):1, the transition metal salt is any one of ruthenium chloride, ferric nitrate and iridium chloride, and the mixture is fully ground for 10-120 min; the mixture after grinding is high-temperature calcined, the temperature is increased to 700-1200℃ at a temperature increasing rate of 1-20℃ / min, and the temperature is kept for 0.5-5 h, and then the temperature is cooled to room temperature, to obtain the carbon-loaded transition metal silicide composite material.

2. The production method according to claim 1, characterized by, The methyl silicone oil is replaced by dimethyl silicone oil.

3. The production method according to claim 1, characterized by, The methyl silicone oil and the transition metal salt are mixed in a mass ratio of 5:1, and the mixture is fully ground for 30 min.

4. The preparation method according to claim 1, characterized in that, The temperature of high-temperature calcination is 1000℃, the temperature is increased to 1000℃ at a temperature increasing rate of 10℃ / min in a programmed temperature increasing mode, and the temperature is kept for 2 h.

5. The preparation method according to claim 1, characterized in that, The mixture is high-temperature calcined in a nitrogen atmosphere.

6. The production method according to claim 5, characterized by, The nitrogen is replaced by argon, hydrogen, a hydrogen / argon mixed gas or a hydrogen / nitrogen mixed gas.

7. The carbon-loaded transition metal silicide composite material prepared by the preparation method in any one of claims 1-6.

8. Application of the carbon-loaded transition metal silicide composite material in claim 7 to electrocatalysis or preparation of an electrocatalytic material.

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