Composite superlattice material for PEM electrolyzed water as well as preparation method and application of composite superlattice material
By preparing PDDA-rGO/RuO2 superlattice materials, the problem of insufficient stability of RuO2 catalysts in acidic electrolytes was solved, and efficient oxygen evolution performance and long-term stability were achieved, which is suitable for PEM water electrolysis systems.
Patent Information
- Application Number
- CN202510822130.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-19
- Publication Date
- 2025-09-09
AI Technical Summary
Traditional RuO2 catalysts are not stable enough in acidic electrolytes and are easily oxidized to a high-valence state, causing lattice oxygen to participate in the reaction and accompanied by the dissolution and deactivation of ruthenium, which limits their long-term operating life and makes it difficult to balance activity and stability.
Using composite superlattice materials, layered potassium ruthenate is formed by mixed annealing of K2CO3 and RuO2, which is then protonated by HCl and exfoliated by tetrabutylammonium hydroxide into single-layer RuO2 nanosheets, which are then compounded with PDDA-rGO to form a PDDA-rGO/RuO2 superlattice, thereby improving the structural stability and activity of the catalyst.
It exhibits excellent oxygen evolution performance and electrode stability in an acidic environment with a low overpotential, which significantly improves the long-term stability and catalytic efficiency of the catalyst.
Smart Images
Figure CN120608303A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of electrocatalytic materials, and specifically relates to a composite superlattice material of ruthenium oxide and graphene for efficient PEM water electrolysis, and a preparation method and application thereof. Background Art
[0002] In the field of electrocatalysis, ruthenium dioxide (RuO2) has been widely studied due to its high activity in the oxygen evolution reaction (OER), especially in acidic electrolytes (such as proton exchange membrane water electrolyzers, PEMWE), where its performance is significantly better than other materials. However, traditional RuO2 catalysts face two major bottlenecks in practical applications: insufficient stability and a trade-off between activity and stability. In the acidic OER process, RuO2 is easily oxidized to a high-valent state (Ru n+ , n>4), leading to lattice oxygen participation in the reaction and the accompanying dissolution and deactivation of ruthenium, severely limiting its long-term operational life. Superlattice catalysts, through the design of periodic interfaces and atomic-level heterojunctions, can simultaneously enhance the intrinsic activity of active sites (such as optimizing the adsorption of OOH* intermediates) and structural stability (such as inhibiting the formation and dissolution of high-valent ruthenium), thereby overcoming the "seesaw" effect of traditional catalysts. Furthermore, the regular pores and confinement effects of the superlattice accelerate mass transfer, further improving catalytic efficiency.
[0003] Therefore, the development of RuO2-based superlattice catalysts is expected to achieve long-term stable operation in acidic environments while maintaining high activity, providing key material support for the next generation of high-efficiency PEMWE technology. Summary of the Invention
[0004] Purpose of the invention: The purpose of the present invention is to provide a composite superlattice material for PEM water electrolysis and its preparation method and application.
[0005] A composite superlattice material for PEM water electrolysis and a preparation method thereof, comprising the following steps:
[0006] Step 1: K2CO3 and RuO2 are mixed and ground into granules, and the mixture is annealed in an inert gas atmosphere to obtain layered potassium ruthenate;
[0007] Step 2: Add the layered potassium ruthenate obtained in step 1 to HCl solution and perform protonation treatment at room temperature to obtain H 0.2 RuO 2.1 nH2O (n=0.5-0.7), centrifuge to obtain the precipitate and dry;
[0008] Step 3: placing the precipitate obtained in step 2 in a tetrabutylammonium hydroxide aqueous solution and stirring to form a colloidal nanosheet suspension; the tetrabutylammonium hydroxide peels off the multilayer RuO2 into a single layer; the tetrabutylammonium hydroxide in the suspension is then centrifuged to remove the tetrabutylammonium hydroxide, and the single-layer ruthenium dioxide nanosheet is obtained after drying;
[0009] Step 5: Disperse the monolayer RuO2 nanosheets with deionized water to form a colloidal suspension, dropwise add the suspension into the PDDA-rGO suspension under continuous stirring at a certain mass ratio, and then centrifuge and dry;
[0010] Step 6: Anneal the mixture obtained in step 5 under an inert gas atmosphere to obtain a composite superlattice material PDDA-rGO / RuO2.
[0011] Preferably, in step 1, the molar ratio of K2CO3 to RuO2 is 5:8, and the annealing temperature used is 700-900°C, preferably 850°C, and the annealing time is preferably 12 hours.
[0012] Preferably, in step 2, the concentration of the HCl solution is 0.5 to 1.5 mol / L, and the layered potassium ruthenate and the HCl solution are mixed at a mass-to-volume ratio of 0.008 to 0.012 g / mL. The total protonation treatment time is 72 hours, and the HCl solution is replaced every 24 hours for a total of three times.
[0013] Preferably, in step 3, the concentration of the tetrabutylammonium hydroxide aqueous solution is 0.02-0.05 mol / L; the stirring time is 10-12 days; and the solid-liquid ratio of the precipitate to the tetrabutylammonium hydroxide aqueous solution is 1 g:250 mL.
[0014] Preferably, in step 4, the preparation method of PDDA-rGO suspension is as follows:
[0015] 1) preparing a graphene oxide suspension by the Hummers method, wherein the concentration of the graphene oxide suspension is 0.1-0.3 mg / mL (preferably 0.2 mg / mL);
[0016] 2) Mix 200 mL of the graphene oxide suspension with 1.5 mL of a 20 wt % PDDA solution. Then, add 15 μL of 98% hydrazine hydrate, heat to 90°C, and continue stirring for 3 hours.
[0017] 3) The resulting slurry was centrifuged at high speed (18,000–20,000 rpm for the first centrifugation). The supernatant was removed and the precipitate was resuspended in deionized water. The solution was centrifuged again (2nd centrifugation at 5,000–8,000 rpm) to remove the precipitate. The resulting supernatant was the final stable PDDA-rGO suspension. 10 mL of the supernatant was freeze-dried and the concentration of PDDA-modified reduced graphene oxide was measured.
[0018] Preferably, in step five, the mass ratio of the single-layer RuO2 nanosheets to the PDDA-rGO is 50:(20-80).
[0019] Preferably, in step six, the annealing temperature is 400° C. and the annealing time is 2 h.
[0020] The composite superlattice material prepared by the above method can be used for electrocatalytic water splitting in an acidic environment.
[0021] Beneficial effects:
[0022] (1) PDDA (polydiallyldimethylammonium chloride) is a strong electron-withdrawing cationic polymer. Graphene modified by PDDA not only improves the dispersibility of graphene in water, but also gives graphene positive charge, providing a good matrix for the preparation of graphene-based composite materials.
[0023] (2) rGO (reduced graphene oxide) composite catalyst has significant performance advantages in the electrolysis of water to produce hydrogen and oxygen. It can improve the efficiency of the reaction and reduce the required overpotential. It is one of the key materials for realizing green hydrogen energy technology.
[0024] (3) Compared with Ir-based catalysts, under the same catalytic conditions, the composite superlattice material catalyst of ruthenium oxide and graphene prepared in the present invention exhibited significantly superior oxygen evolution performance. Specifically, compared with previously reported catalysts of the same type, under the same catalytic conditions (acidic), the oxygen evolution overpotential of PDDA-rGO / RuO2 was 217 mV. Furthermore, the electrode exhibited excellent stability during chronoamperometric measurements. Therefore, the PDDA-rGO / RuO2 catalyst has broad application prospects in the field of acidic oxygen evolution. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 is the XRD pattern of the superlattice material prepared in Example 2;
[0026] Figure 2 The Raman diagrams of the products prepared in Examples 1 to 3 and the comparative example;
[0027] Figure 3 LSV diagrams of the products prepared in Examples 1 to 3 and the comparative example;
[0028] Figure 4 TEM image of the superlattice material prepared in Example 2;
[0029] Figure 5 HRTEM image of the superlattice material prepared in Example 2;
[0030] Figure 6 This is the SEM image of the superlattice material prepared in Example 2. DETAILED DESCRIPTION
[0031] The technical solutions of the present invention are described in detail below through examples, but the protection scope of the present invention is not limited to the examples.
[0032] Example 1
[0033] This example uses 20 mg of PDDA-rGO composite ruthenium dioxide nanosheets, which is abbreviated as PDDA-rGO 0.4 / RuO2, the preparation steps are as follows:
[0034] (1) 1.382 g of K2CO3 and 1.916 g of RuO2 were mixed and ground into granules, and the mixture was annealed at 850°C for 12 hours in an Ar gas atmosphere to obtain layered potassium ruthenate.
[0035] (2) Immerse 2 g of the obtained layered potassium ruthenate in 200 mL of 1 mol / L HCl solution and treat at room temperature for 72 hours (the mass volume ratio of layered potassium ruthenate to HCl solution is 10 g / L) to obtain H 0.2 RuO 2.1 nH2O, n=0.5-0.7, centrifuge to obtain the precipitate and dry it.
[0036] (3) The precipitate was stirred in a 0.03 mol / L tetrabutylammonium hydroxide aqueous solution for 11 days to form a colloidal nanosheet suspension. The tetrabutylammonium hydroxide in the suspension was then centrifuged to remove the tetrabutylammonium hydroxide, and the monolayer ruthenium dioxide nanosheets were obtained after drying. The solid-liquid ratio of the precipitate to the tetrabutylammonium hydroxide aqueous solution was 1 g:250 mL.
[0037] (4) 200 mL of 0.2 mg / mL graphene oxide suspension prepared by the Hummers method was mixed with 1.5 mL of 20 wt % PDDA solution. Next, 15 μL of 98% hydrazine hydrate was added, and the mixture was heated to 90 °C and stirred for 3 h.
[0038] The obtained slurry was centrifuged at 20,000 rpm, the supernatant was removed after centrifugation, the precipitate was resuspended with 200 mL of deionized water, and the solution was centrifuged again at 6,000 rpm. The supernatant after removing the precipitate was the final stable PDDA-rGO suspension. 10 mL of the supernatant was freeze-dried to measure the concentration of PDDA-modified reduced graphene oxide.
[0039] (5) 50 mg of single-layer RuO2 nanosheets were dispersed in 50 mL of deionized water to form a colloidal suspension and a suspension containing 20 mg of PDDA-rGO was added dropwise under continuous stirring and then centrifuged to dry.
[0040] (6) The obtained mixture was annealed at 400 °C in an Ar atmosphere for 2 h to obtain 20 mg of PDDA-rGO composite ruthenium dioxide nanosheets.
[0041] Example 2
[0042] This embodiment uses 50 mg of PDDA-rGO composite ruthenium dioxide nanosheets, which are abbreviated as PDDA-rGO / RuO2, and is prepared by the following method:
[0043] (1) 1.382 g of K2CO3 and 1.916 g of RuO2 were mixed and ground into granules, and the mixture was annealed at 850°C for 12 hours in an Ar gas atmosphere to obtain layered potassium ruthenate.
[0044] (2) Immerse 2 g of the obtained layered potassium ruthenate in 200 mL of 1 mol / L HCl solution and treat at room temperature for 72 hours (the mass volume ratio of the sample to the HCl solution is 10 g / L) to obtain H 0.2 RuO 2.1 nH2O, n=0.5-0.7, centrifuge to obtain the precipitate and dry it.
[0045] (3) The precipitate was stirred in a 0.03 mol / L tetrabutylammonium hydroxide aqueous solution for 11 days to form a colloidal nanosheet suspension. The tetrabutylammonium hydroxide in the suspension was then centrifuged to remove the tetrabutylammonium hydroxide, and the suspension was dried to obtain single-layer ruthenium dioxide nanosheets. The solid-to-liquid ratio of the precipitate to the tetrabutylammonium hydroxide aqueous solution was 1 g:250 mL.
[0046] (4) 200 mL of 0.2 mg / mL graphene oxide suspension prepared by the Hummers method was mixed with 1.5 mL of 20 wt % PDDA solution. Then, 15 μL of 98% hydrazine hydrate was added, and the mixture was heated to 90 °C and stirred for 3 h.
[0047] The obtained slurry was centrifuged at high speed of 20,000 rpm, the supernatant was removed after centrifugation, and the precipitate was resuspended with 200 mL of deionized water. The solution was centrifuged again at 6,000 rpm, and the supernatant after removing the precipitate was the final stable PDDA-rGO suspension. 10 mL of the supernatant was freeze-dried to measure the concentration of PDDA-modified reduced graphene oxide.
[0048] (5) 50 mg of single-layer RuO2 nanosheets were dispersed in 50 mL of deionized water to form a colloidal suspension and a suspension containing 50 mg of PDDA-rGO was added dropwise under continuous stirring and then centrifuged to dry.
[0049] (6) The obtained mixture was annealed at 400 °C in an Ar atmosphere for 2 h to obtain 50 mg of PDDA-rGO composite ruthenium dioxide nanosheets.
[0050] Example 3
[0051] This example uses 80 mg of PDDA-rGO composite ruthenium dioxide nanosheets, which is abbreviated as PDDA-rGO 1.6 / RuO2, prepared by the following method, the steps are:
[0052] (1) 1.382 g of K2CO3 and 1.916 g of RuO2 were mixed and ground into granules, and the mixture was annealed at 850°C for 12 hours in an Ar gas atmosphere to obtain layered potassium ruthenate.
[0053] (2) Immerse 2 g of the obtained potassium ruthenate in 200 mL of 1 mol / L HCl solution and treat at room temperature for 72 hours (the mass volume ratio of the sample to the HCl solution is 10 g / L) to obtain H 0.2 RuO 2.1 nH2O, n=0.5-0.7, centrifuge to obtain the precipitate and dry it.
[0054] (3) The precipitate was stirred in a 0.03 mol / L tetrabutylammonium hydroxide aqueous solution for 11 days to form a colloidal nanosheet suspension. The tetrabutylammonium hydroxide in the suspension was then centrifuged to remove the tetrabutylammonium hydroxide, and the monolayer ruthenium dioxide nanosheets were obtained after drying. The solid-liquid ratio of the precipitate to the tetrabutylammonium hydroxide aqueous solution was 1 g:250 mL.
[0055] (4) 200 mL of 0.2 mg / mL graphene oxide suspension prepared by the Hummers method was mixed with 1.5 mL of 20 wt % PDDA solution. Then, 15 μL of 98% hydrazine hydrate was added, and the mixture was heated to 90 °C and stirred for 3 h.
[0056] The obtained slurry was centrifuged at high speed of 20,000 rpm, the supernatant was removed after centrifugation, and the precipitate was resuspended with 200 mL of deionized water. The solution was centrifuged again at 6,000 rpm, and the supernatant after removing the precipitate was the final stable PDDA-rGO suspension. 10 mL of the supernatant was freeze-dried to measure the concentration of PDDA-modified reduced graphene oxide.
[0057] (5) 50 mg of single-layer RuO2 nanosheets were dispersed in 50 mL of deionized water to form a colloidal suspension and the suspension containing 80 mg of PDDA-rGO was added dropwise under continuous stirring and then centrifuged to dry.
[0058] (6) The obtained mixture was annealed at 400 °C in an Ar atmosphere for 2 h to obtain 80 mg of PDDA-rGO composite ruthenium dioxide nanosheets.
[0059] Comparative Example 1
[0060] A method for preparing ruthenium dioxide nanosheets without PDDA-rGO composite, RuO2, comprises the following steps:
[0061] (1) 1.382 g of K2CO3 and 1.916 g of RuO2 were mixed and ground into granules, and the mixture was annealed at 850°C for 12 hours in an Ar atmosphere to obtain layered potassium ruthenate;
[0062] (2) Immerse 2 g of the obtained potassium ruthenate in 200 mL of 1 mol / L HCl solution and treat at room temperature for 72 hours (the mass volume ratio of the sample to the HCl solution is 10 g / L) to obtain H 0.2 RuO 2.1 nH2O, n=0.5-0.7, centrifuge to obtain the precipitate and dry it.
[0063] (3) The precipitate was stirred in a 0.03 mol / L tetrabutylammonium hydroxide aqueous solution for 11 days to form a colloidal nanosheet suspension. The tetrabutylammonium hydroxide in the suspension was then centrifuged to remove the tetrabutylammonium hydroxide, and the suspension was dried to obtain single-layer RuO2 nanosheets. The solid-to-liquid ratio of the precipitate to the tetrabutylammonium hydroxide aqueous solution was 1 g:250 mL.
[0064] Electrochemical testing: 4.8 mg of the composite superlattice materials prepared in Examples 1-3 and Comparative Example 1 were dispersed in 300 µL of ethanol. 30 µL of Nafion solution was added, and the mixture was sonicated for 20 minutes. 300 µL of deionized water was then added and sonicated for another 20 minutes to form a uniformly dispersed catalyst slurry. 4.7 µL of this catalyst slurry was then dropwise added to a 0.5 mm diameter glassy carbon electrode and dried. This was repeated three times.
[0065] Electrochemical oxygen evolution testing was conducted using a single electrolytic cell, with a catalyst-loaded glassy carbon electrode as the working electrode (anode), a silver chloride electrode as the reference electrode, and a carbon rod as the counter electrode. A 0.5M H₂SO₄ solution was placed in the cell. The linear sweep voltammogram (LSV) curve of the catalyst was measured at room temperature, with the voltage range (reversible hydrogen electrode potential) being 1.5 (0.1) .
[0066] The above method was applied to the electrocatalytic oxygen evolution reaction, and the catalytic performance is shown in Table 1.
[0067]
[0068] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. For example, changing the annealing temperature, but a low annealing temperature will lead to composite failure, and a high temperature will lead to sintering of ruthenium oxide. PDDA-rGO is superior to rGO that is not modified by PDDA in terms of dispersibility and composite stability through surface charge regulation and interface functionalization. Compared with other modification strategies, its core advantage lies in the synergistic effect of charge driving, but the modification strategy needs to be selected according to specific needs. It is not necessary and impossible to illustrate all the embodiments here. The obvious changes or modifications derived from this scheme are still within the scope of protection of the present invention.
[0069] Figure 1 This is the XRD pattern of the superlattice material prepared in Example 2, which shows that the superlattice material of RuO2 composite PDDA-rGO was successfully prepared. Figure 2 The Raman images of the products prepared in Examples 1 to 3 and the comparative example illustrate that the surface structure of RuO2 changes, and the more PDDA-rGO composited with RuO2, the higher the intensity of the Raman peak. Figure 3 The LSV diagrams of the products prepared in Examples 1 to 3 and the comparative example show that the OER performance is best when the mass ratio of RuO2 and PDDA-rGO is 1:1. Figure 4 This is a TEM image of the superlattice material prepared in Example 2, which shows that the prepared superlattice material is flaky. Figure 5 This is the HRTEM image of the superlattice material prepared in Example 2, indicating that the RuO2 composite PDDA-rGO superlattice material was successfully prepared. Figure 6 This is the SEM image of the superlattice material prepared in Example 2, which shows that the prepared superlattice material is in the form of a sheet.
[0070] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to the form and details without departing from the spirit and scope of the present invention.
Claims
1. A method for preparing a composite superlattice material for PEM water electrolysis, characterized in that: The steps include: Step 1: K2CO3 and RuO2 are mixed and ground into granules, and the mixture is annealed in an inert gas atmosphere to obtain layered potassium ruthenate; Step 2: adding the layered potassium ruthenate obtained in step 1 to an HCl solution, performing protonation treatment at room temperature, and then centrifuging to obtain a precipitate and drying it; Step 3: placing the precipitate obtained in step 2 in a tetrabutylammonium hydroxide aqueous solution and stirring to form a colloidal nanosheet suspension, removing the tetrabutylammonium hydroxide in the suspension by centrifugation, and obtaining a monolayer ruthenium dioxide nanosheet after drying; Step 4: preparing PDDA-rGO suspension; Step 5: Disperse the monolayer ruthenium dioxide nanosheets with deionized water to form a colloidal suspension, dropwise add the suspension into the PDDA-rGO suspension under continuous stirring, and then centrifuge and dry; Step 6: annealing the mixture obtained in step 5 under an inert gas atmosphere to obtain a composite superlattice material.
2. The preparation method according to claim 1, characterized in that In step 1, the molar ratio of K2CO3 to RuO2 is 5:8; the annealing temperature is 700~900℃, and the annealing time is 12 hours.
3. The preparation method according to claim 1, characterized in that In step 2, layered potassium ruthenate and HCl solution are mixed at a mass volume ratio of 8-12 g / L, and the concentration of the HCl solution is 0.5-1.5 mol / L.
4. The preparation method according to claim 1, characterized in that In step 2, the total time of protonation treatment is 72 hours, and the HCl solution is replaced every 24 hours.
5. The preparation method according to claim 1, characterized in that In step 3, the solid-liquid ratio of the precipitate to the tetrabutylammonium hydroxide aqueous solution is 1 g:250 mL; the concentration of the tetrabutylammonium hydroxide aqueous solution is 0.02-0.05 mol / L; and the stirring time is 10-12 days.
6. The preparation method according to claim 1, characterized in that In step 4, the preparation method of PDDA-rGO suspension is as follows: 1) Preparation of graphene oxide suspension by Hummers method; 2) Mix the graphene oxide suspension and PDDA solution evenly, then add hydrazine hydrate, heat to 90°C and continue stirring for 3 hours; 3) The obtained slurry is subjected to high-speed centrifugation, the supernatant is removed, the precipitate is resuspended with deionized water, and the precipitate is removed by centrifugation again. The obtained supernatant is the PDDA-rGO suspension.
7. The preparation method according to claim 1, characterized in that In step five, the mass ratio of monolayer ruthenium dioxide nanosheets to PDDA-rGO is 50:(20-80).
8. The preparation method according to claim 1, characterized in that In step six, the annealing temperature is 400° C. and the annealing time is 2 h.
9. A composite superlattice material prepared according to the preparation method according to any one of claims 1 to 8.
10. Use of the composite superlattice material according to claim 9 in electrocatalytic water splitting under acidic environment.