Preparation method of Ru single atom doped Ni(OH)2 coupled with FeOOH and application of the Ru single atom doped Ni(OH)2 coupled with FeOOH in electrolysis of water under industrial current density

Abstract

The application discloses a preparation method of a Ru monatomic doped Ni(OH)2 coupled FeOOH composite nanoelectrocatalyst, and comprises the following steps: step one, pretreating a nickel foam; step two, dissolving 1.2mmol of NiCl6H2O, 5mmol of CO(NH2)2, 0.2mmol of RuCl3xH2O and 1mmol of NaCl in 40mL of deionized water and uniformly stirring; step three, transferring the mixed solution in step two and the pretreated nickel foam into a 100mL polytetrafluoroethylene reaction kettle and reacting at 120 DEG C for 12h; step four, washing the nickel foam after reaction by using deionized water and ethanol several times and then vacuum drying to obtain the Ru SAs / Ni(OH)2 precursor; and step five, immersing the obtained Ru SAs / Ni(OH)2 precursor in a 4.5mg / mL FeSO4 7H2O solution at normal temperature and reacting for 1h, then washing the nickel foam after reaction by using deionized water and ethanol several times and then vacuuming and drying to obtain the Ru SAs / Ni(OH)2@FeOOH electrocatalyst. The preparation process is simple, the precious metal material can be efficiently utilized and the cost is reduced, the electrocatalyst is suitable for industrialized preparation, and the problems that other synthesis technologies are complex and high in cost and cannot meet the industrialized production are solved.

Description

Technical Field

[0001] This invention relates to the field of industrial electrochemical water splitting, and particularly to a method for preparing Ru single-atom doped Ni(OH)2 coupled with FeOOH and its application in water electrolysis at industrial current densities. Background Technology

[0002] With the continuous depletion of traditional fossil fuels such as coal, oil, and natural gas, the global energy crisis and environmental pollution problems are becoming increasingly severe, forcing researchers to search for new alternative energy sources. Hydrogen has a high energy density (142 MJ / kg⁻¹). −1 Hydrogen has advantages such as high efficiency and environmental friendliness, making it the most promising green energy source for the future. Utilizing intermittent energy sources (such as solar, wind, and tidal energy) to drive electrochemical water splitting to produce high-purity hydrogen is an effective method. However, the actual voltage of electrochemical water splitting is 1.23 V higher than the theoretical voltage, meaning that more electrical energy is required to produce hydrogen. Therefore, it is necessary to research and develop electrocatalysts that are cost-effective and possess excellent catalytic performance and stability.

[0003] Synthesizing electrocatalytic materials on porous nickel foam has many advantages. First, the large specific surface area of ​​nickel foam can not only increase the loading of electrocatalysts, but also expose more catalytic active sites. Second, the electrocatalytic materials are grown directly in situ on nickel foam, which reduces the impedance during electron transport. Third, nickel foam has certain mechanical properties, which ensures the structural stability of the self-supporting electrode under the impact of a large number of bubbles.

[0004] Pt-based and Ir / Ru-based nanomaterials are considered state-of-the-art electrocatalysts for HER and OER reactions. However, these precious metals are expensive and unstable, limiting their large-scale industrial applications. Heteroatom doping is an effective method to reduce the cost of catalyst synthesis and improve catalyst performance. First, heteroatoms can alter the microstructure of the incorporated catalyst material, especially by modulating the electronic structure, thereby optimizing the adsorption and desorption of reaction intermediates. Second, the lattice distortion caused by heteroatom doping exposes the active sites of the catalyst. Finally, heteroatoms themselves possess high catalytic activity and simultaneously act as catalytic active sites during the reaction, synergistically enhancing the catalytic performance along with the host material.

[0005] Ru-based catalysts exhibit good adsorption-desorption capabilities for reaction intermediates during electrocatalytic reactions. Furthermore, Ru's price is significantly lower than Pt, approximately one-third of its cost. However, Ru-based catalysts suffer from poor water dissociation, negatively impacting their electrocatalytic activity. Doping other materials with Ru as single atoms is an effective way to enhance electrocatalytic performance. Various methods exist for single-atom doping, such as ion exchange, electrodeposition, and electrodeposition. However, these methods face challenges including complex synthesis processes, uncontrollable synthesis, and unstable synthesized materials. Therefore, designing and preparing a simple, low-cost, and high-performance Ru-doped high-current electrocatalyst is of significant practical importance and represents a pressing technical challenge. Summary of the Invention

[0006] To address the aforementioned problems, a first aspect of the present invention provides a method for preparing a composite nano-electrocatalyst constructed by Ru single-atom doping of Ni(OH)₂ coupled with FeOOH, comprising:

[0007] Step 1: Pre-treat the nickel foam, first preparing a piece of foam with a size of 2 × 4 cm. 2 The nickel foam was immersed in 3 mol / L hydrochloric acid and sonicated for 15 minutes, then sonicated in deionized water for 6 minutes, and finally sonicated in ethanol for 5 minutes, and then air-dried for later use.

[0008] Step 2: Dissolve 1.2 mmol NiCl·6H2O, 5 mmol CO(NH2)2, 0.2 mmol RuCl3·xH2O and 1 mmol NaCl in 40 mL of deionized water and stir well;

[0009] Step 3: Transfer the mixed solution from Step 2 and the pretreated nickel foam to a 100 mL polytetrafluoroethylene reactor and react at 120 °C for 12 h.

[0010] Step 4: Rinse the reacted nickel foam 2-4 times with deionized water and ethanol respectively, then vacuum dry for 6 hours to obtain Ru. SAs / Ni(OH)2 precursor;

[0011] Step 5: Obtain Ru SAs The Ni(OH)₂ precursor was immersed in a 4.5 mg / mL FeSO₄·7H₂O solution at room temperature for 1 h. The resulting nickel foam was then washed 2-4 times with deionized water and ethanol, and then vacuum dried for 6 h to obtain Ru. SAs / Ni(OH)2@FeOOH electrocatalyst.

[0012] According to another aspect of the present invention, a method for preparing Ru-based composite nano-electrocatalysts by Ru single-atom doping of Ni(OH)₂ coupled with FeOOH is provided. SAs Application of / Ni(OH)2@FeOOH electrocatalyst in water electrolysis at industrial current density.

[0013] The above-mentioned technical solution of the present invention has the following beneficial technical effects: The present invention obtains a Ru single-atom doped bifunctional electrocatalyst with high loading (5.13 wt%) and good dispersion through a simple two-step method of hydrothermal method and impregnation method. The preparation process of the present invention is simple, can efficiently utilize precious metal materials and reduce costs, and is suitable for industrial preparation of electrocatalysts, solving the problems of complex and costly synthesis techniques that cannot meet industrial production requirements. The electrocatalyst synthesized by the present invention exhibits HER, OER and total water electrolysis performance far superior to commercial Pt / C, RuO2 and RuO2(+) || Pt / C (-) at industrial current densities. Attached Figure Description

[0014] Figure 1 For Ru SAs Schematic diagram of the synthesis of / Ni(OH)2@FeOOH catalyst;

[0015] Figure 2 For Ni(OH)2, FeOOH, Ru SAs / Ni(OH)2、Ru SAs Raman spectrum of / Ni(OH)2@FeOOH;

[0016] Figure 3 For Ru SAs SEM images of / Ni(OH)2@FeOOH at different magnifications;

[0017] Figure 4 For Ru SAs TEM images of / Ni(OH)2@FeOOH at different magnifications;

[0018] Figure 5 For Ru SAs AC-HAADF-STEM image of / Ni(OH)2@FeOOH;

[0019] Figure 6 The following are electrocatalytic assay results for HER. (a) LSV plots of different synthesized catalysts; (b) overpotentials of the synthesized catalysts at different current densities; (c) Ru SAs / Ni(OH)2@FeOOH and Pt / C at 50 mA cm -2 Stability test results at current density;

[0020] Figure 7 The following are electrocatalytic test results for OER. (a) LSV plots of different synthesized catalysts; (b) overpotentials of the synthesized catalysts at different current densities; (c) Ru SAs / Ni(OH)2@FeOOH and RuO2 at 50 mA cm -2 Stability test results at current density;

[0021] Figure 8 The following are electrocatalytic test results for the complete water electrolysis process. (a) LSV diagrams of different synthesized catalysts; (b) Voltage of the synthesized catalysts at different current densities; (c) Ru SAs / Ni(OH)2@FeOOH(+) || Ru SAs / Ni(OH)2@FeOOH(-)and RuO2(+) || Pt / C(-) at 50 mA cm -2 Stability test results at current density. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0023] like Figure 1 As shown, a method for preparing a composite nano-electrocatalyst constructed by Ru single-atom doping Ni(OH)₂ coupled with FeOOH is provided, comprising:

[0024] Step 1: Pre-treat the nickel foam, first preparing a piece of foam with a size of 2 × 4 cm. 2 The nickel foam was immersed in 3 mol / L hydrochloric acid and sonicated for 15 minutes, then sonicated in deionized water for 6 minutes, and finally sonicated in ethanol for 5 minutes, and then air-dried for later use.

[0025] Step 2: Dissolve 1.2 mmol NiCl·6H2O, 5 mmol CO(NH2)2, 0.2 mmol RuCl3·xH2O and 1 mmol NaCl in 40 mL of deionized water and stir well;

[0026] Step 3: Transfer the mixed solution from Step 2 and the pretreated nickel foam to a 100 mL polytetrafluoroethylene reactor and react at 120 °C for 12 h.

[0027] Step 4: Rinse the reacted nickel foam 2-4 times with deionized water and ethanol respectively, then vacuum dry for 6 hours to obtain Ru. SAs / Ni(OH)2 precursor;

[0028] Step 5: Obtain Ru SAs The Ni(OH)₂ precursor was immersed in a 4.5 mg / mL FeSO₄·7H₂O solution at room temperature for 1 h. The resulting nickel foam was then washed 2-4 times with deionized water and ethanol, and then vacuum dried for 6 h to obtain Ru. SAs / Ni(OH)2@FeOOH electrocatalyst.

[0029] like Figure 2-5 As shown, Figure 2 For Ni(OH)2, FeOOH, Ru SAs / Ni(OH)2、Ru SAs Raman spectrum of / Ni(OH)2@FeOOH; Figure 3 For Ru SAs SEM images of / Ni(OH)2@FeOOH at different magnifications; Figure 4 For Ru SAs TEM images of / Ni(OH)2@FeOOH at different magnifications; Figure 5 For Ru SAs AC-HAADF-STEM image of / Ni(OH)2@FeOOH.

[0030] Ru SAs / Ni(OH)2@FeOOH was prepared by a simple two-step method. First, Ru was grown on a nickel foam matrix framework using a hydrothermal method. SAs / Ni(OH)2 porous nanowire precursor; secondly, by impregnation method on Ru SAs FeOOH clusters are coupled onto the Ni(OH)2 precursor to obtain a high-performance bifunctional electrocatalyst.

[0031] Another aspect of the present invention provides a method for preparing Ru-based composite nano-electrocatalysts by Ru single-atom doping of Ni(OH)₂ coupled with FeOOH. SAs Application of / Ni(OH)2@FeOOH electrocatalyst in water electrolysis at industrial current density.

[0032] like Figure 6 As shown, the HER catalytic activity of the prepared catalyst was tested using a three-electrode system. (The text then abruptly shifts to a seemingly unrelated topic: "using Ru...") SAs / Ni(OH)2@FeOOH is the working electrode (1×1 cm) 2 Using a carbon rod as the counter electrode and Hg / HgO as the reference electrode, Ru was tested in 1 M KOH solution. SAs High-current HER performance of / Ni(OH)2@FeOOH catalyst.

[0033] like Figure 6 a and Figure 6 As shown in b, the prepared Ru SAs The / Ni(OH)2@FeOOH catalyst exhibits excellent HER performance, requiring overpotentials of 105, 209, and 267 mV to achieve 100, 500, and 1000 mA·cm⁻¹, respectively. -2 The current density is superior to Ru's. SAs The performance of the Ni(OH)2 precursor and Ni(OH)2 is far superior to that of the benchmark Pt / C catalyst (η). 100 =138 mV, η 500 =309 mV, η 1000 =426 mV). Furthermore, from Figure 6 c shows that Ru SAs / Ni(OH)2@FeOOH catalyst at 50 mA·cm -2 The stability at high current densities exceeded 160 h, far superior to Pt / C catalysts. This demonstrates that Ru single-atom doping and the introduction of FeOOH clusters significantly improved the HER performance of Ni(OH)₂ under high current conditions, and also indicates that Ru… SAs / Ni(OH)2@FeOOH catalyst has the potential for industrial application.

[0034] like Figure 7 As shown, the OER catalytic activity of the prepared catalyst was tested using a three-electrode system. (The figure shows the OER catalytic activity of Ru...) SAs / Ni(OH)2@FeOOH is the working electrode (1×1 cm) 2 Using a carbon rod as the counter electrode and Hg / HgO as the reference electrode, Ru was tested in 1 M KOH solution. SAs High current OER performance of / Ni(OH)2@FeOOH catalyst.

[0035] like Figure 7 a and Figure 7 As shown in b, Ru SAs / Ni(OH)2@FeOOH catalyst at 100, 500 and 1000 mA·cm -2 The required overpotentials at the current densities were 279, 338, and 386 mV, respectively, which are far superior to those of other comparative samples and the benchmark RuO2(η). 100 = 444 mV, η 500 = 649 mV, η 1000 = 764 mV). This indicates that Ru SAs The synergistic effect of Ni(OH)2 and FeOOH effectively enhances Ru SAsThe OER performance of / Ni(OH)2@FeOOH. In addition, such as... Figure 7 As shown in c, Ru SAs / Ni(OH)2@FeOOH catalyst at 50 mA·cm -2 After stability testing at a current density of [value missing] for at least 180 h, no significant performance degradation was observed, which is superior to the RuO2 catalyst. This provides a simple method for developing noble metal single-atom catalysts.

[0036] like Figure 8 As shown, the performance of the full electrolysis of water was tested. Using Ru... SAs The / Ni(OH)₂@FeOOH electrocatalyst, used simultaneously as both the anode and cathode electrodes in a dual-electrode system, was tested in a 1 M KOH solution during complete water electrolysis and named Ru. SAs / Ni(OH)2@FeOOH(+) || Ru SAs / Ni(OH)2@FeOOH (-). Furthermore, a dual-electrode system was assembled using RuO2 and Pt / C as the anode and cathode electrodes, respectively, as a control sample for testing, and named RuO2(+) || Pt / C(-).

[0037] like Figure 8 a and Figure 8 As shown in b, Ru SAs / Ni(OH)2@FeOOH (+) || Ru SAs The full electrolysis catalytic performance of / Ni(OH)2@FeOOH (-) is far superior to that of the benchmark RuO2(+) || Pt / C(-), especially at high current densities. Specifically, Ru SAs / Ni(OH)2@FeOOH (+) || Ru SAs / Ni(OH)2@FeOOH (-) requires voltages of 1.60, 1.76, 1.85, and 2.50 V to achieve 100, 500, 1000, and 1500 mA cm⁻¹, respectively. -2 The current density is [value missing], while RuO2(+) || Pt / C(-) requires voltages of 1.80, 2.17, 2.37, and 2.50 V respectively to achieve the same current density. Furthermore, as... Figure 8 As shown in c, Ru SAs / Ni(OH)2@FeOOH (+) || Ru SAs The / Ni(OH)2@FeOOH (-) catalyst showed no significant voltage increase after at least 140 h of stability testing, which is far superior to RuO2 (+) || Pt / C (-). This invention provides a new approach for the preparation and modification of highly efficient bifunctional electrocatalysts.

[0038] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A method for preparing a composite nano-electrocatalyst constructed by Ru single-atom doping of Ni(OH)₂ coupled with FeOOH, characterized in that, include: Step 1: Pre-treat the nickel foam, first preparing a piece of foam with a size of 2 × 4 cm. 2 The nickel foam was immersed in 3 mol / L hydrochloric acid and sonicated for 15 minutes, then sonicated in deionized water for 6 minutes, and finally sonicated in ethanol for 5 minutes, and then air-dried for later use. Step 2: Dissolve 1.2 mmol NiCl·6H2O, 5 mmol CO(NH2)2, 0.2 mmol RuCl3·xH2O and 1 mmol NaCl in 40 mL of deionized water and stir well; Step 3: Transfer the mixed solution from Step 2 and the pretreated nickel foam to a 100 mL polytetrafluoroethylene reactor and react at 120 °C for 12 h. Step 4: Rinse the reacted nickel foam 2-4 times with deionized water and ethanol respectively, then vacuum dry for 6 hours to obtain Ru. SAs / Ni(OH)2 precursor; Step 5: Obtain Ru SAs The Ni(OH)₂ precursor was immersed in a 4.5 mg / mL FeSO₄·7H₂O solution at room temperature for 1 h. The resulting nickel foam was then washed 2-4 times with deionized water and ethanol, and then vacuum dried for 6 h to obtain Ru. SAs / Ni(OH)2@FeOOH electrocatalyst.

2. Ru prepared by the method according to claim 1 SAs Application of / Ni(OH)2@FeOOH electrocatalyst in water electrolysis at industrial current density.

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