Preparation Method and Application of Gd-Doped Rutile-Type Ruthenium Dioxide Nanosheets

Abstract

The present invention discloses a preparation method and application of doped Gd rutile-type ruthenium dioxide nanosheets. In the present invention, by using RuCl3 and GdN3O9 as raw materials, doped Gd rutile-type ruthenium dioxide nanosheets are successfully prepared by the salt template method. When used as an oxygen evolution catalyst for hydrogen production by electrolyzing water, it exhibits excellent oxygen evolution performance (OER). At a current density of 10 mA cm-2, an overpotential of only 230 mV is achieved, and at the same time, it has excellent conductivity, a wide potential window, and high redox reversibility. Therefore, it has broad application prospects in the field of electrocatalysis. In addition, the preparation method of the present invention has the characteristics of simple, safe and easy-to-control process steps, easy availability of raw materials, less use of chemical reagents in the whole preparation process, small environmental pollution, mild experimental conditions, short time consumption, and low cost. Therefore, it is suitable for industrial promotion and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of ruthenium dioxide nanomaterial synthesis, and particularly relates to a preparation method and application of doped Gd rutile ruthenium dioxide nanosheets. Background Art

[0002] Electrolytic water hydrogen production is an effective method to obtain clean energy. The electrolytic water reaction is divided into anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER). Among them, the anodic oxygen evolution reaction (OER) involves a four-electron transfer process. Therefore, this half-reaction has problems such as a slow kinetic process and a high overpotential. Usually, a catalyst is introduced to accelerate this process to reduce the overpotential of the electrolytic water reaction.

[0003] Ruthenium dioxide has two variants, one is an amorphous state, and the other is a tetragonal crystal system with a rutile structure. Among them, rutile ruthenium dioxide has a strong anti-electron transfer ability. Ruthenium dioxide has advantages such as an ultra-high mass specific capacitance, excellent electrical conductivity, a wide potential window, and a high degree of redox reversibility, and is often used as an oxygen evolution reaction electrocatalyst in electrolytic water hydrogen production. There are many methods for preparing ruthenium dioxide, such as sol-gel method, direct oxidation method, electrochemical precipitation method, calcination method, etc. Different preparation methods result in great differences in the morphology of ruthenium dioxide obtained, and there are also large differences in its electrochemical properties. Among them, the ruthenium dioxide prepared by the calcination method and the direct oxidation method has larger particles, greater differences in crystal grain shapes, uneven particle size distributions, and the particle size cannot be effectively controlled; hydrolyzing ruthenium chloride acid is a widely used ruthenium dioxide preparation method in the current industrial community. The disadvantage of this preparation method is that it will produce more harmful pollutants, and the uneven particle size distribution of the obtained ruthenium dioxide powder results in a poor resistance film surface; the precipitation method is the most widely used method for liquid-phase chemical synthesis of high-purity nanoscale particles. Its process is simple, and the obtained powder has good performance, but this method still cannot solve the problem of nanoparticle aggregation.

[0004] Due to its low-dimensional structure and highly exposed active sites, nanosheets have shown relatively superior performance in the application of electrolytic water hydrogen production catalysts and are expected to become an efficient new type of electrolytic water hydrogen production catalyst material.

[0005] However, in practical applications, RuO2 is easily oxidized to high-valent RuO4 at high oxidation potentials, resulting in the metal detaching from the lattice and becoming soluble metal cations. This leads to the collapse of the RuO2 crystal structure and the deterioration of its stability, severely limiting the practical application of proton exchange membrane water electrolyzers (PEMWE). Summary of the Invention

[0006] Aiming at the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a preparation method and application of doped Gd rutile ruthenium dioxide nanosheets.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The first aspect of the present invention is to provide a preparation method of doped Gd rutile-type ruthenium dioxide nanosheets, comprising the following steps:

[0009] S1. Dissolve RuCl3 and GdN3O9 in a solvent to prepare a precursor solution;

[0010] S2. Add the obtained precursor solution to NaCl, stir and react, purify, and perform calcination and annealing treatment to obtain a Gd-RuO2 composite material, that is, doped Gd rutile-type ruthenium dioxide nanosheets.

[0011] Preferably, the mass-volume ratio range of RuCl3, GdN3O9, the solvent, and NaCl is 0.08 g to 0.12 g: 0.001 g to 0.003 g: 20 ml to 30 ml: 45 g to 55 g.

[0012] Preferably, in step S2, before adding the obtained precursor solution to NaCl, the precursor solution is ultrasonically treated for 15 to 35 min.

[0013] Preferably, in step S2, the solvent is any one of water, methanol, ethanol, acetone, and ethyl acetate.

[0014] Preferably, in step S2, the temperature during the stirring reaction is 60 to 90 °C, and the stirring reaction time is 3 to 6 h.

[0015] Preferably, in step S2, the purification includes: washing, centrifuging, and drying the reaction product.

[0016] Preferably, the drying temperature is 60 to 70 °C, and the drying time is 12 to 18 h.

[0017] Preferably, the calcination and annealing treatment is carried out in air, and the calcination and annealing temperature is 350 to 500 °C.

[0018] The second aspect of the present invention is to provide the doped Gd rutile-type ruthenium dioxide nanosheets prepared by the above preparation method.

[0019] The third aspect of the present invention is to provide the application of the above doped Gd rutile-type ruthenium dioxide nanosheets as a catalyst in hydrogen production by electrolyzing water.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention uses RuCl3 and GdN3O9 as raw materials, and successfully prepares a Gd-RuO2 composite material, namely doped Gd rutile-type ruthenium dioxide, by means of a salt template method. The obtained doped Gd rutile-type ruthenium dioxide has a nanosheet structure in its microscopic morphology.

[0022] (2) The preparation method of the present invention has the characteristics of simple, safe and easy-to-control process steps, readily available raw materials, few chemical reagents used in the whole preparation process, little environmental pollution, mild experimental conditions, short time consumption, and low cost.

[0023] (3) When the doped Gd rutile-type ruthenium dioxide nanosheets prepared by the present invention are used as an oxygen evolution catalyst for hydrogen production by electrolyzing water, they exhibit excellent oxygen evolution performance (OER). At a current density of 10 mA cm -2 , an overpotential of only 230 mV is achieved. At the same time, it has excellent mass specific capacitance, excellent conductivity, a wide potential window, and high redox reversibility. Therefore, it has broad application prospects in the field of electrocatalysis (such as hydrogen production by electrolyzing water). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is the TEM image of the Gd-RuO2 composite material prepared in Example 1;

[0026] Figure 2 It is the TEM mapping image of the Gd-RuO2 composite material prepared in Example 1;

[0027] Figure 3 It is the XRD pattern of the Gd-RuO2 composite material prepared in Example 1;

[0028] Figure 4 It is the polarization curve graph when the Gd-RuO2 composite material prepared in Example 1 (denoted as Gd-RuO2 in the figure) and commercially available RuO2 (denoted as C-RuO2 in the figure) are used as the anode catalyst for electrolyzing water;

[0029] Figure 5 It is the polarization curve graph when the Gd-RuO2 composite materials prepared in Examples 1-2 and Comparative Examples 1-2 are used as the anode catalyst for electrolyzing water;

[0030] Figure 6Polarization curve of the Gd-RuO2 composite material prepared in Examples 1-3 as an anode catalyst for water electrolysis. Detailed implementation manners

[0031] In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present invention. However, those skilled in the art should clearly understand that the present invention can also be implemented in other embodiments without these specific details.

[0032] Example 1

[0033] A preparation method of Gd-doped rutile-type ruthenium dioxide nanosheets includes the following steps:

[0034] S1. Preparation of the precursor solution:

[0035] Add 0.1 g of RuCl3 and 0.002 g of GdN3O9 into 25 ml of absolute ethanol, and perform ultrasonic treatment for 15 min to obtain the precursor solution;

[0036] S2. Preparation of the Gd-RuO2 composite material, that is, Gd-doped rutile-type ruthenium dioxide:

[0037] Add the obtained precursor solution into a container filled with 50 g of NaCl, stir and react at 80 °C for 4 h. After the reaction is completed, wash and centrifuge the obtained reaction product, then put it into a drying oven and dry at 60 °C for 12 h, and then calcine and anneal at 450 °C in air to obtain the Gd-RuO2 composite material. The SEM, SEM mapping, TEM and XRD spectrum results are shown in Figures 1-4 .

[0038] Example 2

[0039] A preparation method of Gd-doped rutile-type ruthenium dioxide nanosheets includes the following steps:

[0040] S1. Preparation of the precursor solution:

[0041] Add 0.1 g of RuCl3 and 0.001 g of GdN3O9 into 25 ml of absolute ethanol, and perform ultrasonic treatment for 15 min to obtain the precursor solution;

[0042] S2. Preparation of the Gd-RuO2 composite material, that is, Gd-doped rutile-type ruthenium dioxide:

[0043] The obtained precursor solution was added to a container containing 50 g of NaCl, and stirred at 80 °C for 4 h. After the reaction, the obtained reaction product was washed, centrifuged, then placed in a drying oven and dried at 60 °C for 12 h, and then calcined and annealed at 450 °C in air to obtain the Gd-RuO2 composite material.

[0044] Example 3

[0045] A preparation method of Gd-doped rutile-type ruthenium dioxide nanosheets, comprising the following steps:

[0046] S1. Preparation of the precursor solution:

[0047] 0.1 g of RuCl3 and 0.003 g of GdN3O9 were added to 25 ml of absolute ethanol, and ultrasonic treatment was carried out for 15 min to obtain the precursor solution;

[0048] S2. Preparation of the Gd-RuO2 composite material, that is, Gd-doped rutile-type ruthenium dioxide:

[0049] The obtained precursor solution was added to a container containing 50 g of NaCl, and stirred at 80 °C for 4 h. After the reaction, the obtained reaction product was washed, centrifuged, then placed in a drying oven and dried at 60 °C for 12 h, and then calcined and annealed at 450 °C in air to obtain the Gd-RuO2 composite material.

[0050] Example 4

[0051] A preparation method of Gd-doped rutile-type ruthenium dioxide nanosheets, comprising the following steps:

[0052] S1. Preparation of the precursor solution:

[0053] 0.1 g of RuCl3 and 0.002 g of GdN3O9 were added to 25 ml of absolute ethanol, and ultrasonic treatment was carried out for 15 min to obtain the precursor solution;

[0054] S2. Preparation of the Gd-RuO2 composite material, that is, Gd-doped rutile-type ruthenium dioxide:

[0055] The obtained precursor solution was added to a container containing 50 g of NaCl, and stirred at 80 °C for 4 h. After the reaction, the obtained reaction product was washed, centrifuged, then placed in a drying oven and dried at 60 °C for 12 h, and then calcined and annealed at 350 °C in air to obtain the Gd-RuO2 composite material.

[0056] Example 5

[0057] A preparation method of Gd-doped rutile-type ruthenium dioxide nanosheets, comprising the following steps:

[0058] S1. Preparation of precursor solution:

[0059] Add 0.08 g of RuCl3 and 0.002 g of GdN3O9 into 30 ml of methanol, and perform ultrasonic treatment for 35 min to obtain a precursor solution;

[0060] S2. Preparation of Gd-RuO2 composite material, i.e., Gd-doped rutile-type ruthenium dioxide:

[0061] Add the obtained precursor solution into a container containing 55 g of NaCl, stir and react at 60 °C for 3 h. After the reaction, wash and centrifuge the obtained reaction product, then place it in a drying oven at 60 °C for drying for 12 h, and then calcine and anneal it at 450 °C in air to obtain the Gd-RuO2 composite material.

[0062] Example 6

[0063] A preparation method of Gd-doped rutile-type ruthenium dioxide nanosheets includes the following steps:

[0064] S1. Preparation of precursor solution:

[0065] Add 0.12 g of RuCl3 and 0.003 g of GdN3O9 into 20 ml of water, and perform ultrasonic treatment for 25 min to obtain a precursor solution;

[0066] S2. Preparation of Gd-RuO2 composite material, i.e., Gd-doped rutile-type ruthenium dioxide:

[0067] Add the obtained precursor solution into a container containing 45 g of NaCl, stir and react at 90 °C for 6 h. After the reaction, wash and centrifuge the obtained reaction product, then place it in a drying oven at 70 °C for drying for 18 h, and then calcine and anneal it at 500 °C in air to obtain the Gd-RuO2 composite material.

[0068] Comparative Example 1

[0069] The steps are basically the same as those in Example 1, except that 0 g of GdN3O9 is added.

[0070] Comparative Example 2

[0071] The steps are basically the same as those in Example 1, except that 0.004 g of GdN3O9 is added.

[0072] Comparative Example 3

[0073] The steps are basically the same as those in Example 1, except that it is calcined and annealed at 550 °C in air.

[0074] By Figure 1It can be seen from the results that the Gd-RuO2 composite material prepared in Example 1 of the present invention has a flaky microstructure (at a scale of 200 nm).

[0075] From Figure 2 It can be seen from the results that the Gd-RuO2 composite material prepared in Example 1 of the present invention is successfully doped with Gd element, and KCl has been cleaned and obviously has a flaky microstructure.

[0076] From Figure 3 It can be seen from the results that diffraction peaks appear at 27.86° and 34.94°, corresponding to the (110) and (101) crystal planes of RuO2 respectively.

[0077] The Gd-RuO2 composite materials prepared in Examples 1-4 of the present invention, the undoped Gd RuO2 nanomaterial prepared in Comparative Example 1, and the commercially available RuO2 (denoted as C-RuO2) were used as catalysts for electrolytic water hydrogen production for oxygen evolution catalytic activity testing, and at the same time as a control. The electrochemical test was carried out on an electrochemical workstation (CHI 660E) and a standard three-electrode system. The Hg2Cl / Hg (saturated KCl) electrode was used as the reference electrode, and the graphite rod was used as the OER counter electrode. The test was carried out in a 0.1M HClO4 (pH = 1) solution. All linear sweep voltammetry (LSV) curves were recorded at a scan rate of 5 mV s -1 without iR compensation. All potentials were calculated relative to the reversible hydrogen electrode (RHE), and the specific formula was used as follows:

[0078]

[0079] The results are shown in Figures 4-6 .

[0080] From Figures 4-6 It can be seen from the results that compared with the commercially available RuO2, the Gd-RuO2 composite material prepared in Example 1 has better oxygen evolution performance as a catalyst; compared with Comparative Examples 1-2, the Gd-RuO2 composite material prepared in Example 1 has better oxygen evolution performance as a catalyst, and at 10 mA·cm -2At a current density of, an overpotential of only 30 mV was achieved, and at the same time, it has excellent conductivity, a wide potential window, and high redox reversibility. This may be attributed to the fact that doping Gd in RuO2 leads to an elongation of the Ru-O bond length, causing the OER mechanism to shift from LOM to AEM, thus greatly improving the catalytic activity of the catalyst. The results of Comparative Example 2 show that the amount of doped Gd should not be too much, as too much will reduce its catalytic activity. This may be attributed to the fact that when the amount of Gd doping is too much, the Ru-O bond length will be too long, resulting in the dissolution of Ru sites. Compared with Comparative Example 3, the Gd-RuO2 composite materials prepared in Example 1 and Example 4 have more excellent oxygen evolution performance as catalysts, which indicates that the calcination annealing temperature should not be too high, as too high temperature will cause the aggregation of RuO2 and thus seriously reduce its catalytic performance.

[0081] The present invention is not limited to the above specific embodiments. Those of ordinary skill in the art starting from the above concept and making various transformations without creative labor fall within the protection scope of the present invention.

Claims

1. A method for preparing Gd-doped rutile ruthenium dioxide nanosheets, characterized in that: The following steps are involved: S1. Dissolve RuCl3 and GdN3O9 in a solvent to prepare a precursor solution; S2, adding the obtained precursor solution to NaCl, stirring for reaction, purifying, calcining and annealing to obtain Gd-doped rutile ruthenium dioxide nanosheets; The mass volume ratio of the RuCl3, GdN3O9, solvent and NaCl is in the range of 0.08g~0.12g:0.001g~0.003g:20ml~30ml:45g~55g.

2. The method for preparing Gd-doped rutile ruthenium dioxide nanosheets according to claim 1, wherein: In step S2, before adding the obtained precursor solution to NaCl, the precursor solution is ultrasonically treated for 15 to 35 minutes.

3. The method for preparing Gd-doped rutile ruthenium dioxide nanosheets according to claim 1, wherein: In step S2, the temperature during the stirring reaction is 60-90° C., and the stirring reaction time is 3-6 hours.

4. The method for preparing Gd-doped rutile ruthenium dioxide nanosheets according to claim 1, wherein: In step S2, the purification includes washing, centrifuging, and drying the reaction product.

5. The method for preparing Gd-doped rutile ruthenium dioxide nanosheets according to claim 4, characterized in that: The drying temperature is 60-70° C., and the drying time is 12-18 hours.

6. The method for preparing Gd-doped rutile ruthenium dioxide nanosheets according to claim 1, wherein: The calcination and annealing treatment is carried out in air at a temperature of 350-500°C.

7. A Gd-doped rutile ruthenium dioxide nanosheet prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the Gd-doped rutile ruthenium dioxide nanosheets as claimed in claim 7 as a catalyst in hydrogen production by water electrolysis.

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