Preparation method of Re-RuOx nanosheet

Abstract

The invention discloses a preparation method of a two-dimensional Re-RuOx oxygen evolution reaction electrocatalyst. The method comprises the following steps: firstly, preparing a catalyst precursor solution by taking glucose, urea, ruthenium salt and rhenium salt as raw materials, drying the precursor solution, then carrying out oxidizing annealing treatment in a muffle furnace in an air atmosphere, and finally, etching a product in an acid solution to obtain the Re-RuOx catalyst. The rhenium doping of the catalyst effectively regulates the electronic structure and crystal structure of ruthenium dioxide, and endows the catalyst with excellent acidic water electrolysis performance. Through testing, the catalyst can stably run for 400 hours in a three-electrode system; and under the condition of high current density of a PEMWE system, the PEMWE system can stably run for 200 hours, and the PEMWE system shows good application potential.

Description

TECHNICAL FIELD

[0001] The present application relates to a Re-RuO x The application relates to a preparation method of nanosheets, and belongs to the technical field of two-dimensional nanomaterials. BACKGROUND

[0002] As a core technology for preparing green hydrogen, the industrialization of electrochemical water splitting is mainly faced with the contradiction between the kinetic limitation of oxygen evolution reaction (OER) and the cost of catalysts. At present, among noble metal oxide catalysts, IrO2 exhibits excellent stability in proton exchange membrane water electrolysis (PEMWE), but its resource scarcity leads to high cost; and RuO2 has a cost only one fifth of Ir and has considerable catalytic activity, and thus becomes an ideal alternative material. However, Ru-based catalysts are prone to over-oxidation under high potential conditions, generating soluble RuO4 species, which leads to rapid deactivation of the catalyst, and the service life of the Ru-based catalyst is only one third of that of the Ir-based catalyst, forming a core contradiction of "low cost-low stability".

[0003] Current modification strategies mainly include atomic-scale doping of transition metals, construction of core-shell structures or high specific surface area carriers, and design of mesoscopic structures with hierarchical pores to regulate catalytic performance. However, these methods generally face the inherent conflict of "low cost-low stability": although the defect sites introduced by doping can optimize the adsorption of intermediates, they also accelerate the oxidation and dissolution; the core-shell structure and carrier loading can inhibit the agglomeration of catalytic particles, but the interface stress may cause structural instability; the porous structure is helpful for mass transfer, but it is difficult to fundamentally solve the problem of intrinsic stability of active sites. Amorphous-crystalline heterostructures show certain potential by providing an electron transport channel through the crystalline phase, optimizing the intermediate adsorption through the amorphous phase, and inhibiting the reaction path mediated by lattice oxygen, but the low conductivity of the amorphous phase easily leads to local proton accumulation, and the crystallinity of the crystal lattice is difficult to accurately control, resulting in performance fluctuations, and the synergistic optimization of material structure and reaction mechanism has not been realized.

[0004] In-depth analysis shows that the intrinsic stability of Ru-based catalysts is closely related to the covalence of Ru-O bonds. Too strong covalence will inhibit charge transfer, and too weak covalence will easily lead to activation and dissolution of lattice oxygen. Although some studies have achieved selective control of the reaction path by regulating the covalence of Ru-O bonds, verifying the feasibility of optimizing the stability of catalysts from the mechanism level, there is still a lack of methods for constructing heterostructures with controllable crystallinity, and mechanisms for synergistic regulation of lattice strain and covalence, making it difficult to effectively inhibit the problem of oxidation and dissolution while improving the exposure of active sites. This field still needs further exploration to achieve the dual goals of high performance and long service life of the catalyst. SUMMARY

[0005] To address current challenges, this paper proposes a dual strategy combining precise control of amorphous-crystalline heterostructures with optimized Ru–O bond covalency. Specifically, a controlled synthesis technique is used to construct a heterointerface with adjustable crystallinity, leveraging the synergistic effect of the high conductivity of the crystalline phase and the abundant active sites of the amorphous phase. Simultaneously, lattice strain engineering is employed to adjust the covalency of the Ru–O bond, confining the reaction pathway to the mechanistic framework of adsorbate evolution and fundamentally suppressing lattice oxygen loss. Combined with a two-dimensional nanosheet structure, this strategy promotes efficient bubble desorption and mass transfer, ultimately achieving simultaneous improvements in catalytic activity and structural stability. This strategy provides a new approach and paradigm for the development of low-cost, long-life PEMWE electrocatalysts.

[0006] The implementation process of the present invention is as follows: A Re-RuO x The method for preparing the nanosheets comprises the following steps: (1) adding soluble rhenium salt, ruthenium salt, glucose and urea in a molar ratio of 1: (1-20): (40-1000): (30-500) to deionized water to obtain a mixed solution, drying and then grinding to obtain a precursor; (2) subjecting the precursor to an oxidation annealing treatment at 350-500 °C; (3) The annealed product is etched in an acid solution to obtain a rhenium-doped ruthenium dioxide catalyst.

[0007] In the above step (1), the molar ratio of ruthenium salt, rhenium salt, glucose and urea is 1: (1-15): (40-800): (40-450).

[0008] In the above step (1), the soluble ruthenium salt is selected from ruthenium trichloride trihydrate, anhydrous ruthenium trichloride, and ruthenium acetylacetonate.

[0009] In the above step (1), the soluble rhenium salt is rhenium trichloride.

[0010] In the above step (2), the annealing treatment is 2-8 h, and the heating rate is 5 ° C min -1 .

[0011] In the above step (3), the acid solution is 0.3~1 mol L -1 The etching time is 6 to 18 hours.

[0012] The Re-RuO prepared by the above method x The nanosheets have a heterogeneous structure of ruthenium dioxide with an amorphous phase and a crystalline phase, and rhenium is uniformly distributed at the atomic level in the crystalline and amorphous phases of ruthenium dioxide.

[0013] The above Re-RuO xApplication of nanosheets as electrocatalysts for oxygen evolution.

[0014] The beneficial effect of the present invention is that the present invention successfully prepares Re-RuO by a simple pyrolysis annealing method. x Nanosheets are easy to operate. The present invention effectively regulates the structural strain, crystallinity and covalency of RuO2 by adjusting the doping ratio of Re element, thereby inhibiting the peroxidation dissolution of ruthenium dioxide during the oxygen evolution reaction and significantly improving the oxygen evolution performance of the catalyst under acidic conditions. -2 When the catalyst of the present invention is applied to the anode of a proton exchange membrane electrolyzer, it can achieve a reaction rate of 1000 mA·cm at a low voltage of 1.55 V. -2 The high current density of 500 mA·cm -2 It can run continuously for 200 hours at a high current density, fully demonstrating its excellent electrocatalytic performance and long-term stability, providing a strong guarantee for efficient and low-energy hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Re-RuO prepared in Example 1 of the present invention x Transmission electron microscope image of the catalyst; Figure 2 Re-RuO prepared in Example 1 of the present invention x X-ray diffraction patterns of the catalyst and commercial ruthenium dioxide; Figure 3 Re-RuO prepared in Example 1 of the present invention x The catalyst and commercial ruthenium dioxide were tested in 0.5 M sulfuric acid solution at 10 mA cm -2 Comparison of electrocatalytic oxygen evolution activity under current density conditions; Figure 4 Re-RuO prepared in Example 1 of the present invention x The catalyst and commercial ruthenium dioxide were tested in 0.5 M sulfuric acid solution at 10 mA cm -2 Comparison of electrocatalytic oxygen evolution stability under current density conditions; Figure 5 Re-RuO prepared in Example 1 of the present invention x When the catalyst is used as an anode catalyst in a PEM electrolyzer, the -2 Stability curve at high current density. DETAILED DESCRIPTION

[0016] The technical solutions of the present application are further described below with specific examples, but the protection scope of the present application is not limited thereto. If the specific experimental steps or conditions are not indicated in the examples, the operations or conditions can be carried out according to the conventional experimental steps described in the literature in the field. If the reagents or instruments are not indicated by the manufacturer, they are all conventional reagent products that can be obtained by purchase in the market. Example 1

[0017] 104 mg of ruthenium trichloride trihydrate, 29 mg of rhenium trichloride, 5 g of glucose and 1 g of urea were added to 5 ml of deionized water, mixed thoroughly, and then uniformly stirred at 80 ℃ by a magnetic stirrer. After that, the mixture was moved into an oven and dried at 140 ℃ for 8 h, and then thoroughly ground to obtain a precursor.

[0018] The precursor obtained above was heated at a rate of 5 ℃ min -1 The oxidation annealing treatment was carried out at 400 ℃ for 4 h, and the obtained catalyst after annealing was stirred in a 0.5 M hydrochloric acid solution at room temperature for 12 h. After centrifugation, separation, water washing and drying in an oven at a temperature of 80 ℃, a rhenium-doped ruthenium dioxide catalyst was obtained. Example 2

[0019] 104 mg of ruthenium trichloride trihydrate, 116 mg of rhenium trichloride, 5 g of glucose and 1 g of urea were added to 5 ml of deionized water, mixed thoroughly, and then uniformly stirred at 80 ℃ by a magnetic stirrer. After that, the mixture was moved into an oven and dried at 140 ℃ for 8 h, and then thoroughly ground to obtain a precursor.

[0020] The precursor obtained above was heated at a rate of 5 ℃ min -1 The oxidation annealing treatment was carried out at 350 ℃ for 8 h, and the obtained catalyst after annealing was stirred in a 0.5 M hydrochloric acid solution at room temperature for 12 h. After centrifugation, separation, water washing and drying in an oven at a temperature of 80 ℃, a rhenium-doped ruthenium dioxide catalyst was obtained. Example 3

[0021] 104 mg of ruthenium trichloride trihydrate, 116 mg of rhenium trichloride, 5 g of glucose and 1 g of urea were added to 5 ml of deionized water, mixed thoroughly, and then uniformly stirred at 80 ℃ by a magnetic stirrer. After that, the mixture was moved into an oven and dried at 140 ℃ for 8 h, and then thoroughly ground to obtain a precursor.

[0022] The precursor obtained above was heated at a rate of 5 ℃ min -1The obtained catalyst was annealed by oxidation at 500 ℃ for 6 h, and then etched by stirring in 0.5 M hydrochloric acid solution at room temperature for 6 h. The product was centrifuged, separated, washed with water, and dried in an oven at 80 ℃ to obtain the rhenium-doped ruthenium dioxide catalyst. Example 4

[0023] 104 mg of ruthenium trichloride trihydrate, 11.6 mg of rhenium trichloride, 5 g of glucose, and 1 g of urea were added to 5 ml of deionized water and mixed thoroughly. After being uniformly stirred at 80 ℃ by a magnetic stirrer, the mixture was moved into an oven and dried at 140 ℃ for 8 h, and then thoroughly ground to obtain a precursor.

[0024] The obtained precursor was heated at a rate of 5 ℃ / min -1 The obtained catalyst was annealed by oxidation at 450 ℃ for 8 h, and then etched by stirring in 0.5 M hydrochloric acid solution at room temperature for 12 h. The product was centrifuged, separated, washed with water, and dried in an oven at 80 ℃ to obtain the rhenium-doped ruthenium dioxide catalyst. Example 5

[0025] 104 mg of ruthenium trichloride trihydrate, 23.2 mg of rhenium trichloride, 5 g of glucose, and 1 g of urea were added to 5 ml of deionized water and mixed thoroughly. After being uniformly stirred at 80 ℃ by a magnetic stirrer, the mixture was moved into an oven and dried at 140 ℃ for 8 h, and then thoroughly ground to obtain a precursor.

[0026] The obtained precursor was heated at a rate of 5 ℃ / min -1 The obtained catalyst was annealed by oxidation at 350 ℃ for 10 h, and then etched by stirring in 0.5 M hydrochloric acid solution at room temperature for 8 h. The product was centrifuged, separated, washed with water, and dried in an oven at 80 ℃ to obtain the rhenium-doped ruthenium dioxide catalyst. Example 6

[0027] 104 mg of ruthenium trichloride trihydrate, 38.6 mg of rhenium trichloride, 5 g of glucose, and 1 g of urea were added to 5 ml of deionized water and mixed thoroughly. After being uniformly stirred at 80 ℃ by a magnetic stirrer, the mixture was moved into an oven and dried at 140 ℃ for 8 h, and then thoroughly ground to obtain a precursor.

[0028] The obtained precursor was heated at a rate of 5 ℃ / min -1 The obtained catalyst was annealed by oxidation at 400 ℃ for 8 h, and then etched by stirring in 0.5 M hydrochloric acid solution at room temperature for 12 h. The product was centrifuged, separated, washed with water, and dried in an oven at 80 ℃ to obtain the rhenium-doped ruthenium dioxide catalyst.

[0029]

[0030] Figure 1 、 Figure 2 、 Figure 3 The rhenium-doped ruthenium dioxide catalyst is prepared by Example 1 of the present invention. Figure 1 It can be seen that the prepared ruthenium dioxide catalyst presents an obvious two-dimensional sheet structure, which can expose more active sites; Figure 2 It can be seen that the diffraction peak intensity of the prepared rhenium-doped ruthenium dioxide is lower than that of commercial ruthenium dioxide, and the peak position is slightly shifted to a low angle, indicating the characteristics of lower crystallinity and tensile strain of the catalyst.

[0031] At the same time, the electrochemical performance of the rhenium-doped ruthenium dioxide catalyst obtained in Example 1 was tested with commercial ruthenium dioxide. Figure 3 It can be seen that compared with commercial ruthenium dioxide, the rhenium-doped ruthenium dioxide catalyst prepared by the present invention has a greatly improved activity compared with commercial ruthenium oxide, at 10 mA cm -2 , the overpotential is only 200 mV at a current density of Figure 4 This shows that the stability of rhenium-doped ruthenium dioxide catalyst has also been greatly improved.

[0032] The rhenium-doped ruthenium dioxide catalyst prepared in Example 1 of the present invention was applied to a proton exchange membrane water electrolysis device. The rhenium-doped ruthenium dioxide catalyst served as the anode catalyst, and a commercial platinum / carbon catalyst served as the cathode catalyst. The catalyst was assembled into a proton exchange membrane electrolyzer with a naphthol 115 membrane, titanium felt for the anode gas diffusion layer, and carbon paper for the cathode gas diffusion layer. Figure 5 The results were tested at 500 mA cm -2 The stability curve under high current density proves the commercial application prospects of rhenium-doped ruthenium dioxide developed by this method.

[0033] The above description is only a preferred experimental example of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A Re-RuO x The method for preparing nanosheets is characterized in that The following steps are involved: (1) adding soluble rhenium salt, ruthenium salt, glucose and urea in a molar ratio of 1: (1-20): (40-1000): (30-500) to deionized water to obtain a mixed solution, drying and then grinding to obtain a precursor; (2) subjecting the precursor to an oxidation annealing treatment at 350-500 °C; (3) The annealed product is etched in an acid solution to obtain a rhenium-doped ruthenium dioxide catalyst.

2. Re-RuO according to claim 1 x The method for preparing nanosheets is characterized by: In step (1), the molar ratio of ruthenium salt, rhenium salt, glucose and urea is 1: (1-15): (40-800): (40-450).

3. Re-RuO according to claim 1 x The method for preparing nanosheets is characterized by: In step (1), the soluble ruthenium salt is selected from ruthenium trichloride trihydrate, anhydrous ruthenium trichloride, and ruthenium acetylacetonate.

4. Re-RuO according to claim 1 x The method for preparing nanosheets is characterized by: In step (1), the soluble rhenium salt is rhenium trichloride.

5. Re-RuO according to claim 1 x The method for preparing nanosheets is characterized by: In step (2), the annealing treatment is carried out for 2 to 8 h, and the heating rate is 5 ° C min -1 .

6. Re-RuO according to claim 1 x The method for preparing nanosheets is characterized by: In step (3), the acid solution is 0.3~1 mol L -1 of hydrochloric acid solution.

7. Re-RuO prepared by the method of claim 1 x Nanosheets.

8. Re-RuO according to claim 7 x Nanosheets, characterized by: Ruthenium dioxide has a heterogeneous structure of amorphous and crystalline phases, and rhenium is uniformly distributed at the atomic level in the crystalline and amorphous phases of ruthenium dioxide.

9. Re-RuO according to claim 7 x Application of nanosheets as electrocatalysts for oxygen evolution.

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