Preparation method of carbon-loaded ruthenium / ruthenium dioxide two-dimensional nanosheet

Abstract

The invention discloses a preparation method of a carbon-loaded ruthenium / ruthenium dioxide two-dimensional nanosheet, which mainly comprises the following steps: adding inorganic ruthenium salt into inorganic carbonate, uniformly mixing, and drying in a drying oven for not less than 12 hours to prepare a salt material; the method comprises the following steps: heating a uniformly mixed salt material to a target temperature in a crucible in an inert atmosphere in a vertical tubular resistance furnace, introducing Ar gas, fully stirring to form stable liquid molten salt, and lowering an electrode to a specified position below the liquid level of the molten salt in a two-electrode system consisting of a non-carbon anode and a conductive cathode for long-time pulse voltage electrolysis; and after electrolysis is completed, the electrode is lifted away from the liquid level of the molten salt, after the furnace temperature is reduced to the room temperature, a cathode product is stripped, and the carbon-loaded ruthenium / ruthenium dioxide two-dimensional nanosheet is directly obtained after repeated cleaning with deionized water and diluted hydrochloric acid. The method is short in preparation process, low in equipment requirement, environment-friendly in process, free of harmful three-waste emission, flexible, convenient and easy to implement, and meets the requirement of developing a green manufacturing strategy.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical technology, and particularly relates to the field of molten salt electrochemical preparation of micro and nanomaterials, specifically to a method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets. Background Technology

[0002] With the continuous development of society, the utilization of green and sustainable energy has attracted widespread attention, and the efficient conversion and storage of energy is becoming increasingly urgent. Functional materials with catalytic and energy storage properties are indispensable in energy catalytic conversion and storage processes. Carbon-supported ruthenium-based functional powders maintain high reactivity and energy conversion and storage capabilities while saving costs. In particular, carbon-supported ruthenium / ruthenium dioxide nanoparticles, as a catalyst for water electrolysis, exhibit excellent bifunctional catalytic hydrogen evolution and oxygen evolution activities in water electrolysis for hydrogen production (Chinese Patent: Application No. 202110037579.9). In addition, carbon-supported ruthenium / ruthenium dioxide, as an electrode material in emerging energy storage devices such as supercapacitors, exhibits large-capacity and rapid charge storage performance (Mukesh Kumar, Kamal K. Kar, Pradip Paik). Chemical Engineering Journal (2024, 499:156414.). However, the above methods for synthesizing carbon-supported ruthenium / ruthenium dioxide all suffer from problems such as complex precursor reagent use, high difficulty in process control, and significant emissions of waste. Therefore, the use of green electrochemical molten salt electrochemical technology for the controllable preparation of high-value functional powders is of great significance.

[0003] Furthermore, two-dimensional nanosheet structures often possess ultra-high specific surface area, excellent mechanical properties, electronic properties, and interfacial effects. They provide more active sites and improve reaction efficiency (such as the hydrogen evolution catalysis of MoS2). They offer significant advantages in providing more active sites, higher reaction efficiency, increasing electrode-electrolyte contact area, and improving battery / supercapacitor performance. Therefore, the controllable preparation of carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets has value in promoting the superior performance of functional materials. Currently, there are few reports on the preparation of carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets using molten salt electrolysis. Therefore, a green, simple, and highly controllable molten salt electrolysis method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets has been disclosed. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets. This method is based on the control of inorganic ruthenium salts and carbonates as raw materials, and fully coordinates electrolysis parameters including electrolysis temperature, pulse voltage, electrolysis time, and electrode surface state to establish a synergistic co-electrodeposition of ruthenium and carbon. It controls the reduction degree of carbon and ruthenium and the template deposition effect to form a carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheet structure. The electrolysis process produces virtually no polluting waste gas or waste liquid emissions, meeting the current development needs of a low-carbon, green, and circular economy.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets, characterized in that the method includes the following steps: Step 1: Add the inorganic ruthenium salt to the inorganic carbonate and mix evenly. Then place it in a vacuum drying oven to dry, and obtain a uniformly mixed salt material. Step 2: In a vertical tube resistance furnace, the uniformly mixed salt material obtained in Step 1 is heated to the target temperature in a crucible under an inert atmosphere. Ar gas is introduced into the molten pool formed by the uniformly mixed salt material through a corundum tube and stirred thoroughly to form a stable liquid molten salt. Then, in a two-electrode system consisting of a non-carbon anode and a conductive cathode, the electrodes are lowered to a designated position below the molten salt surface for long-term pulse voltage electrolysis. Step 3: After the electrolysis in Step 2 is completed, the electrode is lifted off the molten salt surface. After the furnace temperature drops to room temperature, the cathode product is peeled off. After repeated washing with deionized water and dilute hydrochloric acid, carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets are directly obtained.

[0006] The above-mentioned method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets is characterized in that the inorganic ruthenium salt in step one is RuCl3, RuCl3·nH2O, K2RuCl6 or Na2RuCl5·nH2O; the amount of inorganic ruthenium salt added is 5% to 10% of the mass of the uniformly mixed salt.

[0007] The above-mentioned method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets is characterized in that the inorganic carbonate in step one is any two of Na2CO3, Li2CO3, K2CO3, CaCO3, MgCO3 and BaCO3, the amount of inorganic carbonate added is 90%~95% of the mass of the uniformly mixed salt, and the drying temperature is above 100℃ and the time is not less than 12h.

[0008] The above-mentioned method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets is characterized in that, in step two, the non-carbon anode is a NiFe2O4-based rod, a TiB2-based rod, a SnO2 rod, or a RuO2•TiO2 rod, and the diameter of the non-carbon anode is not less than 10 mm; the conductive cathode is a stainless steel sheet, a nickel sheet, or a titanium sheet, and the thickness is not more than 1 mm.

[0009] In this invention, RuO2·TiO2 refers to a composite electrode of RuO2 and TiO2.

[0010] The method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets described above is characterized in that, before using the conductive cathode described in step two, it is pretreated by polishing on sandpaper with a mesh size of not less than 1500.

[0011] The above-mentioned method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets is characterized in that the target temperature in step two is 700℃~800℃, and the Ar gas is introduced and stirred for a duration of not less than 10 min.

[0012] The above-mentioned method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets is characterized in that, during the electrolysis in step two, the pulse voltage of the non-carbon anode relative to the conductive cathode is set as follows: high voltage of 4.0V~6.0V, low voltage of 2.5V~4.0V, pulse width of 1s~5s, and total electrolysis time of not less than 6h.

[0013] The above-mentioned method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets is characterized in that the designated position in step two is no more than 20 mm below the surface of the molten salt, and the descent depth of the non-carbon anode is not less than the descent depth of the conductive cathode.

[0014] In this invention, the specified position being no more than 20 mm below the molten salt surface means that the bottom of the electrode extends no more than 20 mm below the molten salt surface.

[0015] The method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets described above is characterized in that the thickness of the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets in step three is not greater than 50 nm.

[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention uses full carbonate as a flux to form a pre-conversion between ruthenium raw material and flux, which is beneficial to the formation of ruthenium oxide and provides a prerequisite for ruthenium dioxide to be loaded onto the cathode to reduce carbon.

[0017] 2. By controlling the ratio of ruthenium raw materials, this invention enables the electroactive material of ruthenium to be loaded in real time and in situ onto the cathode carbon under the synergistic effect of chemical and electrochemical conversion.

[0018] 3. The electrolysis process of the present invention does not require external intervention. Carbon, ruthenium, and ruthenium dioxide can self-assemble at the cathode to form carbon-supported ruthenium / ruthenium dioxide composite nanosheet powder.

[0019] 4. This invention, through precise control of the electrolytic pulse voltage, enables the formation of incompletely reduced CO bubbles during carbon deposition under high voltage, providing a template for the formation of sheet-like structures. This, in conjunction with the smoothed pre-treated flat plate electrode, provides the conditions for depositing carbon-supported ruthenium / ruthenium dioxide nanosheet structures. Simultaneously, by controlling the low pulse voltage and effective pulse width, effective depolarization is achieved, mitigating the differences in ruthenium and carbon deposition kinetics and ensuring the homogeneity of carbon-supported ruthenium / ruthenium dioxide.

[0020] 5. The preparation process of this invention is simple, requires little equipment, is environmentally friendly with no harmful waste emissions, is flexible and convenient, easy to implement, and meets the needs of developing green preparation methods.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a photograph of the product on the conductive nickel cathode after electrolysis in Embodiment 1 of the present invention.

[0023] Figure 2 The image shows the XRD pattern of the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets obtained in Example 1 of this invention.

[0024] Figure 3 This is a low-magnification SEM image of the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets obtained in Example 1 of the present invention.

[0025] Figure 4 This is a high-magnification SEM image of the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets obtained in Example 1 of the present invention.

[0026] Figure 5 for Figure 3 The EDS component analysis results at position A. Detailed Implementation

[0027] Example 1 This embodiment includes the following steps: Step 1: Add 7.5g of RuCl3•nH2O to 142.5g of the eutectic salt of Na2CO3 and Li2CO3, and then dry it in a vacuum drying oven at 100℃ for 15h to obtain a uniformly mixed salt. Step 2: In a vertical tube resistance furnace, the uniformly mixed salt material obtained in Step 1 is heated to 700℃ in a crucible under an inert atmosphere. Ar gas is introduced into the molten pool formed by the uniformly mixed salt material through a corundum tube and stirred thoroughly for 30 minutes to form a stable liquid molten salt. Then, in a two-electrode system consisting of a 10mm diameter SnO2 rod non-carbon anode and a 1mm thick conductive nickel sheet cathode, the anode is lowered to 15mm below the molten salt surface and the cathode is lowered to 10mm below the molten salt surface. Under pulse voltage conditions with the anode-to-cathode pulse voltage set to: high voltage 4.0V, low voltage 2.5V, and pulse width 5s, long-term pulse voltage electrolysis is performed for 6 hours. Before use, the conductive nickel sheet cathode is pre-treated by polishing on 1500-grit sandpaper. Step 3: After the electrolysis in Step 2 is completed, the electrode is lifted off the molten salt surface. After the furnace temperature drops to room temperature, the cathode product is peeled off. After repeated washing with deionized water and dilute hydrochloric acid, carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets are directly obtained.

[0028] In this embodiment, the inorganic ruthenium salt can also be RuCl3, K2RuCl6 or Na2RuCl5·nH2O, and the inorganic carbonate can also be a eutectic salt composed of any two of Na2CO3, Li2CO3, K2CO3, CaCO3, MgCO3 and BaCO3.

[0029] In this embodiment, the non-carbon anode can also be a NiFe2O4-based rod, a TiB2-based rod, or a RuO2·TiO2 rod, and the conductive cathode can also be a titanium sheet or a stainless steel sheet.

[0030] Figure 1 This is a photograph of the product on the conductive cathode sheet after electrolysis in this embodiment. Figure 1 As can be seen, in this embodiment, carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets are effectively deposited on the conductive cathode sheet.

[0031] Figure 2 The image shows the XRD pattern of the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets obtained in this embodiment. Figure 2 It can be seen that the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets obtained in this embodiment are mainly composed of carbon, ruthenium, and ruthenium dioxide, which meets the composition requirements of carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets.

[0032] Figure 3 This is a low-magnification SEM image of the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets obtained in this embodiment. Figure 4 This is a high-magnification SEM image of the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets obtained in this embodiment. Figure 3 and 4As can be seen, the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets obtained in this embodiment have obvious two-dimensional sheet structure, with a thickness of no more than 50 nm, and exhibit good uniformity characteristics, which meets the structural requirements of carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets.

[0033] Figure 5 for Figure 3 The EDS component analysis results at position A are from... Figure 5 As can be seen, the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets obtained in this embodiment are mainly composed of ruthenium, carbon, and oxygen elements, and carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets have been successfully obtained.

[0034] Testing revealed that the thickness of the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets prepared in this embodiment is no greater than 50 nm.

[0035] Example 2 This embodiment includes the following steps: Step 1: Add 15g of RuCl3•nH2O to 135g of the eutectic salt of Na2CO3 and Li2CO3, and then dry it in a vacuum drying oven at 100℃ for 15h to obtain a uniformly mixed salt. Step 2: In a vertical tubular resistance furnace, the uniformly mixed salt material obtained in Step 1 is heated to 800℃ in a crucible under an inert atmosphere. Ar gas is introduced into the molten pool formed by the uniformly mixed salt material through a corundum tube and stirred thoroughly for 10 minutes to form a stable liquid molten salt. Then, in a two-electrode system consisting of a 10mm diameter NiFe2O4 base rod non-carbon anode and a 1mm thick conductive nickel sheet cathode, the anode is lowered to 20mm below the molten salt surface and the cathode is lowered to 15mm below the molten salt surface. Electrolysis is performed for 10 hours under a pulse voltage set with the anode-to-cathode pulse voltage as follows: high voltage 6.0V, low voltage 4.0V, and pulse width 1s. Before use, the conductive nickel sheet cathode is pre-treated by polishing on 2000-grit sandpaper. Step 3: After the electrolysis in Step 2 is completed, the electrode is lifted off the molten salt surface. After the furnace temperature drops to room temperature, the cathode product is peeled off. After repeated washing with deionized water and dilute hydrochloric acid, carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets are directly obtained.

[0036] In this embodiment, the inorganic ruthenium salt can also be RuCl3, K2RuCl6 or Na2RuCl5·nH2O, and the inorganic carbonate can also be a eutectic salt composed of any two of Na2CO3, Li2CO3, K2CO3, CaCO3, MgCO3 and BaCO3.

[0037] In this embodiment, the non-carbon anode can also be a SnO2 rod, a TiB2-based rod, or a RuO2·TiO2 rod, and the conductive cathode can also be a titanium sheet or a stainless steel sheet.

[0038] Testing revealed that the thickness of the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets prepared in this embodiment is no greater than 50 nm.

[0039] Example 3 This embodiment includes the following steps: Step 1: Add 10g of RuCl3•nH2O to 140g of the eutectic salt of Na2CO3 and Li2CO3, and then dry it in a vacuum drying oven at 100℃ for 20h to obtain a uniformly mixed salt. Step 2: In a vertical tube resistance furnace, the uniformly mixed salt obtained in Step 1 is heated to 750°C in a crucible under an inert atmosphere. Ar gas is introduced into the molten pool formed by the uniformly mixed salt through a corundum tube and stirred thoroughly for 20 minutes to form a stable liquid molten salt. Then, in a two-electrode system consisting of a 10mm diameter SnO2 rod non-carbon anode and a 1mm thick conductive stainless steel sheet cathode, the anode is lowered to 18mm below the molten salt surface and the cathode is lowered to 15mm. Electrolysis is performed for 8 hours under pulse conditions with the anode-to-cathode pulse voltage set to: high voltage 4.5V, low voltage 3.0V, and pulse width 2.0s. Before use, the conductive stainless steel sheet cathode is pre-treated by polishing on 1800-grit sandpaper. Step 3: After the electrolysis in Step 2 is completed, the electrode is lifted off the molten salt surface. After the furnace temperature drops to room temperature, the cathode product is peeled off. After repeated washing with deionized water and dilute hydrochloric acid, carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets are directly obtained.

[0040] In this embodiment, the inorganic ruthenium salt can also be RuCl3, K2RuCl6 or Na2RuCl5·nH2O, and the inorganic carbonate can also be a eutectic salt composed of any two of Na2CO3, Li2CO3, K2CO3, CaCO3, MgCO3 and BaCO3.

[0041] In this embodiment, the non-carbon anode can also be a NiFe2O4-based rod, a TiB2-based rod, or a RuO2·TiO2 rod, and the conductive cathode can also be a titanium sheet or a nickel sheet.

[0042] Testing revealed that the thickness of the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets prepared in this embodiment is no greater than 50 nm.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets, characterized in that, The method includes the following steps: Step 1: Add the inorganic ruthenium salt to the inorganic carbonate and mix evenly. Then place it in a vacuum drying oven to dry, and obtain a uniformly mixed salt material. Step 2: In a vertical tube resistance furnace, the uniformly mixed salt material obtained in Step 1 is heated to the target temperature in a crucible under an inert atmosphere. Ar gas is introduced into the molten pool formed by the uniformly mixed salt material through a corundum tube and stirred thoroughly to form a stable liquid molten salt. Then, in a two-electrode system consisting of a non-carbon anode and a conductive cathode, the electrodes are lowered to a designated position below the molten salt surface for long-term pulse voltage electrolysis. Step 3: After the electrolysis in Step 2 is completed, the electrode is lifted off the molten salt surface. After the furnace temperature drops to room temperature, the cathode product is peeled off. After repeated washing with deionized water and dilute hydrochloric acid, carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets are directly obtained.

2. The method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets according to claim 1, characterized in that, The inorganic ruthenium salt mentioned in step one is RuCl3, RuCl3·nH2O, K2RuCl6 or Na2RuCl5·nH2O; the amount of inorganic ruthenium salt added is 5% to 10% of the mass of the uniformly mixed salt.

3. The method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets according to claim 1, characterized in that, The inorganic carbonate mentioned in step one is any two of Na2CO3, Li2CO3, K2CO3, CaCO3, MgCO3 and BaCO3. The amount of inorganic carbonate added is 90% to 95% of the mass of the uniformly mixed salt material. The drying temperature is above 100℃ and the time is not less than 12 hours.

4. The method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets according to claim 1, characterized in that, In step two, the non-carbon anode is a NiFe2O4-based rod, a TiB2-based rod, a SnO2 rod, or a RuO2•TiO2 rod, and the diameter of the non-carbon anode is not less than 10 mm; the conductive cathode is a stainless steel sheet, a nickel sheet, or a titanium sheet, and the thickness does not exceed 1 mm.

5. The method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets according to claim 1, characterized in that, Before using the conductive cathode described in step two, it should be pre-treated by polishing on sandpaper with a grit of at least 1500.

6. The method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets according to claim 1, characterized in that, The target temperature in step two is 700℃~800℃, and the Ar gas is introduced into the stirring for no less than 10 minutes.

7. The method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets according to claim 1, characterized in that, In step two, the pulse voltage of the non-carbon anode relative to the conductive cathode during electrolysis is set as follows: high voltage is 4.0V~6.0V, low voltage is 2.5V~4.0V, pulse width is 1s~5s, and the total electrolysis time is not less than 6h.

8. The method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets according to claim 1, characterized in that, The designated position mentioned in step two is no more than 20 mm below the molten salt surface, and the descent depth of the non-carbon anode is no less than the descent depth of the conductive cathode.

9. The method for preparing carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets according to claim 1, characterized in that, The thickness of the carbon-supported ruthenium / ruthenium dioxide two-dimensional nanosheets described in step three is no greater than 50 nm.

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