Preparation method and application of Ru-decorated Co7Fe3 electrocatalyst constructed based on hydrotalcite precursor
By preparing a Ru-doped Co7Fe3 electrocatalyst on a hydrotalcite precursor, the problems of insufficient activity and stability of existing catalysts were solved, realizing a highly efficient water electrolysis hydrogen production process and reducing costs.
Patent Information
- Application Number
- CN202511816124.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-04
- Publication Date
- 2026-01-16
AI Technical Summary
Existing catalysts have insufficient electrocatalytic activity and stability in the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. Furthermore, precious metal catalysts are limited in resources and expensive, making it difficult to achieve commercial application.
A method for preparing a Ru-doped Co7Fe3 electrocatalyst based on a hydrotalcite precursor was adopted. By uniformly dispersing Ru particles and Co7Fe3 alloy particles on reduced graphene oxide (rGO), the reactive sites were made into full contact with the alkaline electrolyte, thereby enhancing the electrocatalytic activity.
The reaction kinetics of OER and HER were improved, the HER performance of CoFe alloy was optimized, and it exhibited good stability and conductivity, reducing the amount of precious metals used and achieving efficient hydrogen production by water electrolysis.
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Figure CN121344646A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of electrocatalysts, and particularly relates to a preparation method and application of a Ru-decorated Co7Fe3 electrocatalyst based on a hydrotalcite precursor. BACKGROUND
[0002] Under the macro background that traditional fossil energy needs to be replaced by renewable energy, hydrogen energy is widely considered as the most potential energy due to its environmental-friendly combustion product and high energy density, and plays an important role in the future energy development pattern. Among many methods for preparing hydrogen (H2), hydrogen (H2) and oxygen (O2) can be obtained by electrolysis of water with the aid of renewable energy, and the combustion product of hydrogen is water, which forms a cycle and meets the needs of economy and environmental protection. Therefore, electrolysis of water to prepare hydrogen is considered as an extremely attractive carbon-free strategy. However, the catalyst needs to meet the requirements of cathode hydrogen evolution reaction (HER) and anode oxygen evolution reaction (OER) at the same time, so as to have good catalytic performance and stability. So far, Pt / C and IrO2 are considered as the most effective HER and OER catalysts, but they are difficult to realize commercial application due to their limited resources and high cost. Transition metal-based catalysts have the advantage of controllable cost, but their electrocatalytic activity and stability still need to be improved. Therefore, the main strategy is to explore high-efficiency and stable noble metal composite transition metal-based materials, which not only can reduce the content of noble metals and effectively control the preparation cost, but also can improve the performance of transition metal catalysts, and is expected to be applied as a bifunctional noble metal-free catalyst in overall water splitting. SUMMARY
[0003] The technical problem to be solved by the application is to provide a preparation method and application of a Ru-decorated Co7Fe3 electrocatalyst based on a hydrotalcite precursor, which solves the problems of the prior art.
[0004] To solve the above technical problems, the technical scheme adopted by the application is as follows: a preparation method of a Ru-decorated Co7Fe3 electrocatalyst based on a hydrotalcite precursor, the method comprises the following steps: S1, Co(NO3)2·6H2O and Fe(NO3)·H2O are added to deionized water, and after ultrasonic dispersion, a metal salt mixed solution A is obtained; S2, graphene is added to deionized water, and after ultrasonic dispersion, a graphene B solution is obtained; S3, citric acid is dissolved in deionized water, and after ultrasonic dispersion, a citric acid C solution is obtained; S4, NaOH, Na2CO3 were added into deionized water, and after ultrasonic dispersion, an alkaline solution D was obtained; S5, the citric acid C solution obtained in S3 was added into the graphene B solution obtained in S2, and after ultrasonic mixing for 5 min, the alkaline solution D obtained in S4 was added dropwise into the system, the pH value of the system was maintained at 10±0.1, and stirring was performed for 10 min to obtain a mixed solution E; S6, the metal salt mixture A solution obtained in S1 was slowly added into the mixed solution E obtained in S5, and at the same time, the alkaline solution D obtained in S4 was slowly added into the system, the pH value of the system was maintained at 10±0.1, and after the metal salt mixture A solution was completely added, stirring was continued for 20 min, and finally a mixed solution F was obtained; S7, the mixed solution F obtained in S6 was placed into a polytetrafluoroethylene lined kettle, the polytetrafluoroethylene lined kettle was placed into a hydrothermal kettle, the hydrothermal kettle was placed in an oven, and hydrothermal reaction was performed at a temperature of 80℃ for 12 h, and then natural cooling was performed to room temperature, washing with deionized water was performed until neutral, and after freeze-drying, a CoFe-LDH / GO precursor was obtained; S8, the CoFe-LDH / GO precursor obtained in S7 was added into ethylene glycol, and after ultrasonic, RuCl3·3H2O was added, and after ultrasonic, stirring reaction was performed at an oil bath temperature of 120℃ for 3 h, and then natural cooling was performed to room temperature, centrifugal washing with deionized water was performed until neutral, and after vacuum drying, in a mixed gas atmosphere of H2 and Ar, the temperature was increased from room temperature to 500℃ at a temperature increasing rate of 5 ℃ / min, and reduction was performed at constant temperature for 2 h, and then natural cooling was performed to room temperature, to obtain a Ru-decorated Co7Fe3 electrocatalyst based on a hydrotalcite precursor, denoted as Ru / Co7Fe3 / rGO.
[0005] Preferably, the amount ratio of Co(NO3)2·6H2O, Fe(NO3)·H2O and deionized water in S1 is 0.6 g:0.2 g:30 mL.
[0006] Preferably, the amount ratio of graphene and deionized water in S2 is 40 mg:50 mL.
[0007] Preferably, the amount ratio of citric acid and deionized water in S3 is 19.2 mg:10 mL.
[0008] Preferably, the amount ratio of NaOH, Na2CO3 and deionized water in S4 is 1.28 g:1.06 g:30 mL.
[0009] Preferably, the freeze-drying conditions in S7 are: -30℃, 24 h.
[0010] Preferably, the conditions of the vacuum drying in S8 are: 60℃, 12h, and the volume fraction of H2 in the mixed atmosphere of H2 and Ar is 10%.
[0011] Preferably, the ratio of the use amount of the CoFe-LDH / GO precursor, ethylene glycol and RuCl3·3H2O in S8 is 0.2g: 50mL: 0.032g.
[0012] The application also provides the use of the Ru-decorated Co7Fe3 electrocatalyst based on the hydrotalcite precursor prepared by the preparation method.
[0013] Compared with the prior art, the application has the following advantages: The Ru particles and Co7Fe3 alloy particles uniformly dispersed on the reduced graphene oxide (rGO) are prepared by using the layer plate confinement effect of the hydrotalcite, the reaction active sites are promoted to fully contact the alkaline electrolyte, and the electrocatalytic activity is improved; the introduction of Ru promotes the process of alloy water splitting, adjusts the Gibbs function of the reaction intermediates in the oxygen evolution process and the hydrogen evolution process, and thus improves the reaction kinetics of OER and HER, so as to optimize the HER performance of the CoFe alloy. The reduced graphene oxide (rGO) with a high specific surface area not only plays a role in dispersing the alloy and preventing the alloy particles from aggregating in the stability test, but also improves the conductivity of the catalyst, and the mesoporous structure of the reduced graphene oxide (rGO) further promotes the contact between the alkaline KOH electrolyte and the alloy particles.
[0014] The application will be further described in detail below in combination with the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS
[0015] Figure 1 is a scanning electron microscope image of the Ru-decorated Co7Fe3 electrocatalyst based on the hydrotalcite precursor prepared in Example 1 of the application.
[0016] Figure 2 is a high-resolution transmission electron microscope image of the Ru-decorated Co7Fe3 electrocatalyst based on the hydrotalcite precursor prepared in Example 1 of the application.
[0017] Figure 3 is an XRD image of the Ru-decorated Co7Fe3 electrocatalyst based on the hydrotalcite precursor prepared in Example 1 of the application.
[0018] Figure 4 is a nitrogen adsorption-desorption curve and pore size distribution graph of the Ru-decorated Co7Fe3 electrocatalyst based on the hydrotalcite precursor in Example 1 of the application.
[0019] Figure 5are the LSV curves (a) and the overpotential histograms (b) of GO, CoFe-LDH / GO, Co7Fe3 / rGO, Ru / Co7Fe3 / rGO and Pt / C in Example 1 of the present application at 10 mA cm-2. -2
[0020] Figure 6 are the LSV curves (a), the overpotential histograms (b) and the voltage at 10 mA cm-2(c) of GO, CoFe-LDH / GO, Co7Fe3 / rGO, Ru / Co7Fe3 / rGO and RuO2 in Example 1 of the present application at 10 mA cm-2. -2 -2 -2 DETAILED DESCRIPTION
[0021] Example 1 The preparation method of the present embodiment for constructing Ru-decorated Co7Fe3 electrocatalyst based on hydrotalcite precursor is as follows: S1, 0.6g Co(NO3)2·6H2O, 0.2g Fe(NO3)·H2O were added to 30mL deionized water, and after ultrasonic dispersion, metal salt mixture A liquid was obtained; S2, 40mg graphene was added to 50mL deionized water, and after ultrasonic dispersion, graphene B solution was obtained; S3, 19.2mg citric acid was dissolved in 10mL deionized water, and after ultrasonic dispersion, citric acid C solution was obtained; S4, 1.28g NaOH, 1.06g Na2CO3 were added to 30mL deionized water, and after ultrasonic dispersion, alkaline solution D was obtained; S5, the citric acid C solution obtained in S3 was added to the graphene B solution obtained in S2, and after ultrasonic mixing for 5min, the alkaline solution D obtained in S4 was added dropwise to the system, the pH value of the system was maintained at 10±0.1, and stirring was carried out for 10min to obtain mixture E; S6, the metal salt mixture A liquid obtained in S1 was slowly added to the mixture E obtained in S5, and at the same time, the alkaline solution D obtained in S4 was slowly added to the system, the pH value of the system was maintained at 10±0.1, and after the metal salt mixture A liquid was added, stirring was continued for 20min, and finally mixture F was obtained; S7. The mixed solution F obtained in S6 is placed in a polytetrafluoroethylene-lined reactor, which is then placed in a hydrothermal reactor. The hydrothermal reactor is placed in an oven and subjected to hydrothermal reaction at 80°C for 12 hours. After that, it is naturally cooled to room temperature, washed with deionized water until neutral, and then freeze-dried at -30°C for 24 hours to obtain the CoFe-LDH / GO precursor. S8. Add 0.2g of the CoFe-LDH / GO precursor obtained in S7 to 50mL of ethylene glycol. After sonication, add 0.032g of RuCl3·3H2O. After sonication, stir the reaction in an oil bath at 120℃ for 3h. Then, let it cool naturally to room temperature, wash with deionized water until neutral, and vacuum dry at 60℃ for 12h. Then, in a mixed atmosphere of H2 and Ar (H2 volume fraction of 10%), heat from room temperature to 500℃ at a heating rate of 5℃ / min, reduce at this temperature for 2h, and then let it cool naturally to room temperature to obtain the Ru-doped Co7Fe3 electrocatalyst based on the hydrotalcite precursor, which is the Ru / Co7Fe3 / rGO electrocatalyst.
[0022] like Figure 1 As shown in the scan image of the prepared Ru / Co7Fe3 / rGO electrocatalyst, dispersed particles on the graphene substrate were observed. Graphene can improve the conductivity of the material and also promote the dispersion of alloy particles, thereby improving the performance of water electrolysis.
[0023] like Figure 2 As shown in the high-resolution transmission spectrum of the prepared Ru / Co7Fe3 / rGO electrocatalyst, two types of crystal particles were observed: a crystal with an interplanar spacing of 0.234 nm corresponds to the (100) crystal plane of the Ru nanoparticles; and a crystal with an interplanar spacing of 0.142 nm corresponds to the (200) crystal plane of the Co7Fe3 particles. This transmission spectrum confirms the formation of Ru and Co7Fe3 particles, demonstrating the successful preparation of the Ru / Co7Fe3 / rGO catalyst.
[0024] like Figure 3 The XRD pattern of the prepared Ru / Co7Fe3 / rGO electrocatalyst is shown. The CoFe-LDH precursor exhibits the characteristic peaks of hydrotalcite. After impregnation with RuCl3·3H2O solution, freeze-drying, and high-temperature calcination, the prepared Ru / Co7Fe3 / rGO electrocatalyst exhibits the characteristic peaks of Co7Fe3, proving the successful preparation of the Ru / Co7Fe3 / rGO electrocatalyst.
[0025] This invention utilizes the lamellar confinement effect of hydrotalcite to prepare Ru particles and Co7Fe3 alloy particles uniformly dispersed on reduced graphene oxide (rGO), promoting sufficient contact between reactive sites and alkaline electrolytes and enhancing electrocatalytic activity. The introduction of Ru promotes the alloy water decomposition process and regulates the Gibbs function of reaction intermediates in the oxygen evolution and hydrogen evolution processes, thus simultaneously improving the reaction kinetics of OER and HER, achieving the goal of optimizing the HER performance of the CoFe alloy. rGO, with its high specific surface area, Figure 4 The catalyst has a specific surface area of 99.01 m² / g (a) and a pore size of 1–60 nm (b). It not only disperses the alloy and prevents the alloy particles from agglomerating during stability testing, but also improves the conductivity of the catalyst. Its mesoporous structure further promotes the contact between the KOH electrolyte and the alloy particles.
[0026] The present invention also provides the application of the Ru-doped Co7Fe3 electrocatalyst based on the hydrotalcite precursor prepared by the above preparation method, wherein the Ru-doped Co7Fe3 electrocatalyst based on the hydrotalcite precursor is used for hydrogen production by water electrolysis in alkaline KOH electrolyte.
[0027] The Ru / Co7Fe3 / rGO catalyst prepared in this embodiment was used for HER (hydrogen evolution reaction at the cathode) and OER (oxygen evolution reaction at the anode) performance tests, respectively. The results showed that the composite achieved 10 mA / cm² in a 1.0 M KOH electrolyte. 2 The required HER overpotential is 152 mV, and the Tafel slope is 100 mV dec. -1 After 50 hours of continuous reaction, the retention rate reached 93%, demonstrating excellent stability.
[0028] At the same current density, its OER overpotential is 280 mV, and the Tafel slope is 42 mV dec. -1 After 40 hours of constant voltage chronopotential testing, the current density retention rate still reached 83%, demonstrating the good OER stability of the composite. In a two-electrode system for water electrolysis, using this catalyst as both cathode and anode, at 10 mA / cm²... 2 The required voltage is only 1.65V, and the stability remains at 88% after 40 hours of cycling.
[0029] This embodiment also included HER tests on the prepared GO, CoFe-LDH / GO, Co7Fe3 / rGO and Pt / C electrocatalysts.
[0030] GO: In step S2 of this embodiment, 40 mg of graphene is added to 50 mL of deionized water and dispersed by ultrasonication to obtain graphene B solution; CoFe-LDH / GO: The CoFe-LDH / GO precursor prepared in step S6 of this embodiment; Co7Fe3 / rGO: The preparation method is the same as steps S1-S7 in this embodiment, except that RuCl3·3H2O is not added in S7; Ru / Co7Fe3 / rGO: The Ru-doped Co7Fe3 electrocatalyst based on the hydrotalcite precursor prepared in this embodiment; Pt / C: The commercially available catalyst purchased in this embodiment was used directly for the water electrolysis performance test.
[0031] like Figure 5 (a) and Figure 5 As shown in (b), at a current density of 10 mA / cm², the prepared GO exhibits virtually no HER performance, with an overpotential as high as 440 mV. The HER overpotentials of CoFe-LDH / GO and Co7Fe3 / rGO are 352 mV and 289 mV, respectively, significantly lower than those of the Ru / Co7Fe3 / rGO catalyst (152 mV). Furthermore, the HER activity exhibited by the Ru / Co7Fe3 / rGO catalyst is closer to that of the commercial catalyst Pt / C (47 mV). This demonstrates that Ru-Co7Fe3 / rGO possesses excellent HER performance.
[0032] This embodiment also included OER tests on the prepared GO, CoFe-LDH / GO, Co7Fe3 / rGO, and RuO2 electrocatalysts. Figure 6 (a) and Figure 6 As shown in (b), at a current density of 10 mA / cm², the prepared GO exhibits virtually no OER performance, with an overpotential as high as 380 mV. The OER overpotentials of CoFe-LDH / GO and Co7Fe3 / rGO are 340 mV and 290 mV, respectively, significantly lower than those of the Ru / Co7Fe3 / rGO catalyst (280 mV). Furthermore, the HER activity exhibited by the Ru / Co7Fe3 / rGO catalyst is closer to that of the commercial catalyst RuO2 (200 mV). This demonstrates that Ru-Co7Fe3 / rGO possesses excellent OER catalytic activity.
[0033] This embodiment also included two-electrode water electrolysis experiments with the prepared CoFe-LDH / GO, Co7Fe3 / rGO, and Ru-Co7Fe3 / rGO electrocatalysts, such as... Figure 6 As shown in (c) and (d), Ru-Co7Fe3 / rGO exhibits superior water electrolysis performance. At a current density of 10 mA / cm², it requires a voltage of 1.65 V, and the performance retention rate can still reach 88% after 40 hours of continuous water electrolysis. This demonstrates that Ru-Co7Fe3 / rGO has excellent electrocatalytic activity.
[0034] 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 the preparation of Ru-decorated Co7Fe3 electrocatalysts based on hydrotalcite precursors, characterized by, The method comprises: S1, Co(NO3)2·6H2O, Fe(NO3)·H2O are added to deionized water, and after ultrasonic dispersion, a metal salt mixture A liquid is obtained; S2, graphene is added to deionized water, and after ultrasonic dispersion, a graphene B solution is obtained; S3, citric acid is dissolved in deionized water, and after ultrasonic dispersion, a citric acid C solution is obtained; S4, NaOH, Na2CO3 are added to deionized water, and after ultrasonic dispersion, an alkaline solution D is obtained; S5, the citric acid C solution obtained in S3 is added to the graphene B solution obtained in S2, ultrasonic mixing is performed for 5 minutes, then the alkaline solution D obtained in S4 is added dropwise into the system, the pH value of the system is maintained at 10±0.1, and stirring is performed for 10 minutes to obtain a mixed liquid E; S6, the metal salt mixture A liquid obtained in S1 is added dropwise into the mixed liquid E obtained in S5, and the alkaline solution D obtained in S4 is added dropwise into the system at the same time, the pH value of the system is maintained at 10±0.1, and after the metal salt mixture A liquid is added dropwise, stirring is continuously performed for 20 minutes, and finally a mixed solution F is obtained; S7, the mixed solution F obtained in S6 is subjected to hydrothermal reaction at a temperature of 80℃ for 12 hours, and then naturally cooled to room temperature, washed with deionized water until neutral, and freeze-dried to obtain a CoFe-LDH / GO precursor; S8, the CoFe-LDH / GO precursor obtained in S7 is added to ethylene glycol, ultrasonic is performed, then RuCl3·3H2O is added, ultrasonic is performed, then stirring reaction is performed at an oil bath temperature of 120℃ for 3 hours, then naturally cooled to room temperature, centrifugal washing is performed with deionized water until neutral, vacuum drying is performed, then heating is performed from room temperature to 500℃ at a heating rate of 5 ℃ / min in a mixed gas atmosphere of H2 and Ar, isothermal reduction is performed for 2 hours, then naturally cooled to room temperature, and a Ru-decorated Co7Fe3 electrocatalyst based on a hydrotalcite precursor is obtained, which is denoted as Ru / Co7Fe3 / rGO.
2. The method for constructing Ru-decorated Co7Fe3 electrocatalysts based on hydrotalcite precursors according to claim 1, characterized in that, The amount ratio of Co(NO3)2·6H2O, Fe(NO3)·H2O and deionized water in S1 is 0.6g:0.2g:30mL.
3. The method for constructing Ru-decorated Co7Fe3 electrocatalyst based on hydrotalcite precursor according to claim 1, characterized in that, The amount ratio of graphene and deionized water in S2 is 40mg:50mL.
4. The method for constructing Ru-decorated Co7Fe3 electrocatalysts based on hydrotalcite precursors according to claim 1, characterized in that, The amount ratio of citric acid and deionized water in S3 is 19.2mg:10mL.
5. The method for constructing Ru-decorated Co7Fe3 electrocatalysts based on hydrotalcite precursors according to claim 1, characterized in that, The amount ratio of NaOH, Na2CO3 and deionized water in S4 is 1.28g:1.06g:30mL.
6. The method for constructing Ru-decorated Co7Fe3 electrocatalysts based on hydrotalcite precursors according to claim 1, characterized in that, The freeze-drying condition in S7 is: -30℃, 24h.
7. The method according to claim 1, wherein the method for constructing Ru-decorated Co7Fe3 electrocatalysts based on hydrotalcite precursors is characterized by, The vacuum drying condition in S8 is: 60℃, 12h, the volume fraction of H2 in the mixed gas atmosphere of H2 and Ar is 10%.
8. The method for constructing Ru-decorated Co7Fe3 electrocatalyst based on hydrotalcite precursor according to claim 1, characterized in that, The amount ratio of the CoFe-LDH / GO precursor, ethylene glycol and RuCl3·3H2O in S8 is 0.2g:50mL:0.032g.
9. Use of a Ru-decorated Co7Fe3 electrocatalyst based on hydrotalcite precursors prepared according to the preparation process of any one of claims 1 to 8, characterized in that, The Ru-decorated Co7Fe3 electrocatalyst based on a hydrotalcite precursor is used for electrolysis of water to produce hydrogen in an alkaline KOH electrolyte.