A highly stable basic her catalyst and methods of making and using same

Abstract

The application belongs to the technical field of electrocatalytic water decomposition, and particularly relates to a high-stability alkaline HER catalyst and a preparation and application method thereof; the method adopts a double-source electron beam evaporation deposition system to prepare a Pt:CeO2 film layer, introduces the CeO2 film layer as a Pt supporting layer to prevent Pt from falling off, and simultaneously realizes self-repair of the catalyst active center by adding Pt species in an electrolyte, so as to cooperatively solve the dissolution problem of Pt under dynamic conditions, and realize large-scale application of the high-efficiency and stable Pt-based catalyst. Compared with the prior art, the application cooperatively combines the stabilizing effect of the CeO2 supporting layer and the self-repairing effect of the Pt species in the electrolyte, so that the catalyst realizes high activity and super-long-term stability under alkaline conditions at the same time, and the preparation method is simple and convenient for large-scale application.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic water splitting technology, specifically relating to a highly stable alkaline HER catalyst and its preparation and application methods. Background Technology

[0002] With the rapid development of the global economy and the continuous improvement of people's living standards, energy demand is increasing daily. Currently, over-reliance on non-renewable resources such as coal and natural gas not only exacerbates environmental pollution but also poses a long-term risk of resource depletion. Therefore, promoting the transformation of the energy structure towards a green, clean, and renewable direction has become a global consensus. Among numerous new energy carriers, hydrogen, due to its high energy density, low cost, high efficiency, and cleanliness, is considered the most promising ideal energy carrier for the future and one of the most representative clean energy sources. Among various hydrogen production technologies, water electrolysis is considered the green hydrogen production path with the greatest potential for sustainable development because it uses water directly as a raw material and has near-zero carbon emissions.

[0003] The hydrogen evolution reaction (HER), a key cathode reaction in water electrolysis, is a research focus in the field of electrochemical energy conversion. This reaction provides a direct pathway to achieving green and low-cost hydrogen energy supply by efficiently reducing protons or water molecules to hydrogen. Because the HER requires a high overpotential, the process of producing hydrogen through water electrolysis consumes a large amount of energy. Therefore, introducing highly efficient catalysts is a core strategy for reducing the activation energy and overpotential. Noble metal-based materials (such as Pt, Ru, Rh, Ir, and Pd) have become the focus of current research and application due to their high activity in HER and their ability to significantly reduce the overpotential of water electrolysis.

[0004] Hydrogen production via water electrolysis can be achieved in either acidic or alkaline electrolytes. The highly corrosive acidic environment not only poses safety hazards but also affects the long-term stability of the system. In contrast, alkaline electrolysis systems offer significant advantages: firstly, their operating costs are significantly reduced, and secondly, their system stability is greatly improved. Pt is widely recognized as the best HER catalyst because it exhibits almost no overpotential at startup. However, Pt catalysts undergo dynamic dissolution under specific electrochemical conditions: as the potential increases, a layer of platinum oxide or platinum hydroxide forms on the platinum surface, dissolving in the alkaline electrolyte. Therefore, the long-term stability of Pt-based catalysts remains a significant challenge.

[0005] To address the long-term stability issue of Pt-based catalysts, current research widely employs strategies such as alloying, core-shell structures, and strong metal-support interactions. Among these, utilizing the strong interaction between metal oxide supports and Pt to stabilize Pt nanoparticles has emerged as a promising design approach. However, there are currently no reports on synergistically addressing the stability problem of Pt catalysts through both metal oxide support stabilization and Pt species self-repair in the electrolyte. Summary of the Invention

[0006] The purpose of this invention is to provide a highly stable alkaline HER catalyst and its preparation and application methods, so as to solve the problems of insufficient long-term stability of Pt catalysts in alkaline electrolytes and the difficulty in achieving both high activity and ultra-long-term stability in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing a highly stable basic HER catalyst includes the following steps:

[0009] Step 1: Clean and dry the fluorine-doped tin oxide conductive glass;

[0010] Step 2: An Ag conductive thin film layer is deposited in the first region of the cleaned fluorine-doped tin oxide conductive glass substrate using electron beam deposition.

[0011] Step 3: Using dual-source electron beam deposition, a Pt:CeO2 thin film layer is deposited in the second region on the fluorine-doped tin oxide conductive glass substrate treated in step 2. The second region does not overlap with the first region to avoid interference between the conductive layer and the catalytic precursor layer. At the same time, CeO2 is used as the Pt loading layer to prevent Pt from falling off in alkaline solution.

[0012] Step 4: Weld the conductive wire to the Ag conductive thin film layer obtained in Step 2 to form an ohmic contact, and encapsulate it to obtain the Pt:CeO2 / FTO electrode;

[0013] Step 5: Prepare an alkaline test solution containing Pt active species. During the electrocatalytic water splitting process, the active center of the catalyst is self-repaired through the leaching and redeposition of Pt species.

[0014] Furthermore, in step 2, the first region is defined by a mask, and the deposition rate of the Ag conductive thin film layer is 1 to 5 Å / s, with a deposition thickness of 2 µm.

[0015] Furthermore, in step 3, the first region is blocked by a mask to define the second region. The deposition rate of Pt is 0.1 Å / s and the deposition thickness is 30 Å. The deposition rate of CeO2 is 0.15-0.25 Å / s and the deposition thickness is 45-75 Å.

[0016] Furthermore, in step 5, the alkaline test solution containing the Pt active species is a 1.0 mol / L KOH solution containing H₂PtCl₆. . 6H₂O, its concentration is 8.7 × 10⁻⁶ -5 mol / L.

[0017] The highly stable basic HER catalyst prepared by the above method includes: a fluorine-doped tin oxide conductive glass substrate;

[0018] An Ag conductive thin film layer is formed on a first region of the fluorine-doped tin oxide conductive glass substrate; the Ag conductive thin film layer is connected to a wire and has an ohmic contact with the conductive part.

[0019] A Pt-doped CeO2 thin film layer, namely a Pt:CeO2 thin film layer, is formed on the second region of the fluorine-doped tin oxide conductive glass substrate. The second region does not overlap with the first region.

[0020] The Pt:CeO2 thin film layer serves as a catalyst layer, and Pt is uniformly doped into the CeO2 thin film in the Pt:CeO2 thin film layer. The CeO2 thin film layer also serves as a support layer to prevent Pt from falling off in alkaline solutions.

[0021] Furthermore, in the CeO2 thin film uniformly doped with Pt, Pt exists in a zero valence state.

[0022] A method for applying a highly stable alkaline HER catalyst to electrocatalytic water splitting for hydrogen production in an alkaline electrolyte involves placing the highly stable alkaline HER catalyst as the cathode in an alkaline KOH electrolyte containing Pt active species to carry out an electrocatalytic water splitting reaction. During the reaction, the active sites of the catalyst are self-repaired through leaching and redeposition of Pt species.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) The structural stability of the catalyst is significantly improved by introducing a CeO2 supporting layer. This invention uses a dual-source electron beam evaporation deposition system to prepare a Pt-doped CeO2 thin film, referred to simply as a Pt:CeO2 thin film or Pt:CeO2 precursor thin film. The Pt:CeO2 thin film is used as the catalyst layer, and uniform doping of Pt in the CeO2 film is achieved by controlling the deposition rate of Pt and CeO2. The introduced CeO2 serves as a Pt supporting layer, and its strong interaction with Pt effectively prevents Pt from detaching in alkaline solutions, thereby significantly improving the structural stability of the catalyst under alkaline conditions.

[0025] 2) In-situ self-repair of the catalyst active site is achieved by adding Pt species to the electrolyte. This invention adds Pt active species, such as H₂PtCl₆, to the alkaline test solution. . In the electrocatalytic water splitting process, the leaching-redeposition process of the Pt catalytic active center (6H2O) enables in-situ self-repair of the catalyst active center, effectively compensating for the dissolution loss of Pt during long-term operation and maintaining the high activity of the catalyst.

[0026] 3) The two methods described above work synergistically to achieve both high activity and ultra-long-term stability. By combining the stabilizing effect of the CeO2 support layer with the self-repairing effect of Pt species in the electrolyte, the Pt:CeO2 / FTO electrode prepared in this invention simultaneously achieves high catalytic activity and ultra-long-term stability under alkaline conditions.

[0027] 4) The preparation method of this invention is simple and easy to scale up. Employing electron beam deposition, the method uses a mask to achieve partitioned deposition, resulting in strong process controllability and good reproducibility, providing strong technical support for the large-scale application of Pt-based alkaline HER catalysts. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of the preparation method of the present invention;

[0029] Figure 2 The surface SEM image of the Pt:CeO2 catalyst;

[0030] Figure 3 XPS phase characterization of Pt:CeO2 thin films prepared by a dual-source electron beam evaporation deposition system; where a is the XPS full spectrum of the Pt:CeO2 thin film and b is the XPS characteristic peak spectrum of Pt 4f in the Pt:CeO2 thin film.

[0031] Figure 4 The graphs show the performance of the FTO electrode in electrocatalytic water splitting, where a is the linear sweep voltammetric curve of the Pt:CeO2 / FTO electrode and b is the chronopotential curve of the Pt:CeO2 / FTO electrode. Detailed Implementation

[0032] To better understand the purpose, structure, and function of this invention, the invention will be described in further detail below with reference to the accompanying drawings. Embodiment 1 is a preferred embodiment of the technical solution of this invention, Embodiment 2 is a comparative embodiment of Embodiment 1, and Embodiment 3 is a comparative embodiment of Embodiment 2, used to verify the technical advantages of this invention.

[0033] Example 1

[0034] like Figure 1 As shown in this embodiment, a method for preparing a highly stable alkaline HER catalyst includes the following steps:

[0035] Step 1: Substrate cleaning:

[0036] Fluorine-doped tin oxide conductive glass (FTO) was selected as the substrate and ultrasonically cleaned for 15 minutes each with precision detergent, deionized water, acetone, and isopropanol. The corresponding cleaning reagent was replaced after each cleaning step to ensure that there was no oil or impurities on the substrate surface. After cleaning, the substrate was dried with nitrogen and set aside for later use.

[0037] Step 2: Preparation of Ag conductive thin film layer. In this embodiment, the Ag conductive thin film layer is prepared by electron beam deposition. The specific operation is as follows:

[0038] The cleaned FTO from step 1 was placed in the sample stage of the electron beam deposition system. Ag was used as the deposition source and placed in the crucible within the chamber. A 0.1 cm × 1.0 cm mask was then inserted, depositing an Ag conductive layer film only on the first region of the FTO surface. The system was then evacuated until the chamber vacuum reached 5 × 10⁻⁶. -6 After Torr is applied, the deposition process is started. During the deposition process, a quartz crystal oscillator is used to control the deposition rate of the Ag source and the deposition thickness of the film. The deposition rate is controlled at 1 Å / s and the deposition thickness is controlled at 2 µm. After deposition, an Ag conductive thin film layer is obtained.

[0039] Step 3: Preparation of Pt:CeO2 precursor film. In this embodiment, a dual-source electron beam deposition method is used to prepare the Pt-doped CeO2 precursor film. The specific operation is as follows: The sample prepared in Step 2 is placed in the sample stage of the dual-source electron beam deposition system. Pt (platinum) and CeO2 are used as the deposition sources of the oxide precursor, and are placed in two crucibles in the chamber respectively. The Ag conductive film layer is masked with a mask, and the Pt:CeO2 precursor film is deposited only in the area on the FTO surface where the Ag conductive layer has not been deposited, i.e., the second region. The system is started and evacuated until the vacuum degree of the chamber reaches 5×10⁻⁶. -6 After the Torr process is initiated, the deposition procedure is started. During the deposition process, two quartz crystal oscillators are used to control the deposition rate and deposition thickness of the two sources respectively. The deposition rate of Pt is 0.1 Å / s and the deposition thickness is 30 Å, while the deposition rate of CeO2 is 0.2 Å / s and the deposition thickness is 60 Å, so as to achieve uniform doping of Pt in CeO2 film and obtain Pt:CeO2 precursor film.

[0040] Step 4: Preparation of Pt:CeO2 / FTO electrode:

[0041] The conductive wires were welded to the Ag conductive layer obtained in step 2 using indium metal. After welding, the weld was sealed and covered with a curing adhesive to ensure good ohmic contact and avoid poor contact affecting subsequent electrochemical tests. Finally, the Pt:CeO2 / FTO electrode, which is the highly stable alkaline HER catalyst described in this invention, was prepared.

[0042] Step 5: Preparation of alkaline test solution

[0043] First, prepare a 1.0 mol / L KOH solution: Weigh 62.34 g of 90% KOH, dissolve it in 1 L of deionized water, and dilute to volume. Shake well and set aside. Take 100 mL of the prepared KOH solution and place it in a water electrolysis cell. Add 10 μL of H₂PtCl₆·6H₂O solution to make the concentration of H₂PtCl₆·6H₂O in the test solution 8.7 × 10⁻⁶. -5 mol / L. The H2PtCl6·6H2O added to the test solution serves as a Pt catalyst precursor, which can replenish the active Pt species lost by the cathode hydrogen evolution catalyst during electrocatalytic water splitting, thus achieving catalyst self-repair.

[0044] Step 6: Electrochemical testing and evaluation:

[0045] Using a three-electrode system, the Pt:CeO2 / FTO electrode prepared in step 4 was used as the working electrode, and the electrocatalytic water splitting to hydrogen production was tested in the test solution prepared in step 5 to evaluate its HER catalytic activity and stability. The test results showed that the catalyst has efficient and stable hydrogen evolution performance.

[0046] The highly stable alkaline HER catalyst prepared in this embodiment includes a fluorine-doped tin oxide conductive glass substrate, an Ag conductive thin film layer formed in a first region of the substrate, a Pt:CeO2 thin film layer formed in a second region of the substrate, i.e., a region that does not overlap with the Ag conductive thin film layer, and conductive wires that form ohmic contacts with the Ag conductive layer; wherein the Pt:CeO2 thin film layer is also called the catalyst layer, in which Pt is uniformly doped in the CeO2 thin film and exists in the zero valence state.

[0047] Example 2:

[0048] As a comparative example 1, its preparation steps and testing methods are basically the same as those of example 1, the only difference being that: no CeO2 support layer was introduced, and no CeO2 film was deposited in step 3, only a Pt film was deposited. The specific operation is as follows:

[0049] Step 3: Preparation of Pt Thin Film: Place the sample prepared in Step 2 into the sample stage of the dual-source electron beam deposition system. Use only Pt as the deposition source in the crucible within the chamber. Use a mask to block the Ag conductive layer, depositing the Pt thin film only on the areas of the FTO surface where the Ag conductive layer is not deposited. Start the system to evacuate the vacuum chamber until the vacuum level reaches 5 × 10⁻⁶. -6 After Torr, the deposition process is started, and a quartz crystal oscillator is used to control the deposition rate and thickness of the Pt source. The Pt deposition rate is 0.1 Å / s and the deposition thickness is 30 Å. After deposition, a Pt thin film is obtained.

[0050] The remaining steps (steps 1, 2, 4, 5, and 6) are completely consistent with those in Example 1, and a Pt / FTO electrode is finally prepared. The electrocatalytic water splitting test results are shown in [Figure 1]. Figure 4 Compared with Example 1, the catalytic stability of this comparative sample decreased significantly, proving that the CeO2 support layer plays a key role in improving catalyst stability.

[0051] Example 3:

[0052] As a comparative example 2, its preparation steps and testing methods are basically the same as those of example 1, the only difference being that: H2PtCl6·6H2O solution was not added to the KOH solution, and the test solution was only a 1mol / L KOH solution. The specific operation is as follows:

[0053] Step 5: Preparation of alkaline test solution: Prepare a 1.0 mol / L KOH solution by weighing 62.34 g of 90% KOH, dissolving it in 1 L of deionized water and making up to volume, then shaking well. Take 100 mL of the above-prepared KOH solution into a water electrolysis cell, without adding H2PtCl6·6H2O solution. The test solution is only a 1 mol / L KOH solution.

[0054] The remaining steps (steps 1, 2, 3, 4, and 6) are completely consistent with those in Example 1. A Pt:CeO2 / FTO electrode was prepared using the above method, and its electrocatalytic water splitting test results are shown below. Figure 4 .

[0055] Using the product obtained in Example 1 as a sample, the technical effect was verified:

[0056] Figure 2 This is a SEM image of the surface morphology of the Pt:CeO2 catalyst. From... Figure 2 The surface morphology of the Pt:CeO2 catalyst can be clearly observed, indicating the uniformity of the thin film prepared by the electron beam evaporation equipment.

[0057] Figure 3 XPS phase characterization of Pt:CeO2 thin films prepared using a dual-source electron beam evaporation apparatus. Figure 3 As shown in (a) and (b), the Pt:CeO2 thin film prepared by electron beam evaporation equipment has Pt in the +0 valence state as the main component, which can be used as a HER catalyst. At the same time, Ce element was observed, indicating that CeO2 support layer was successfully introduced during the preparation process.

[0058] Figure 4 The graph shows the performance of FTO electrode electrocatalytic water splitting. Figure 4As shown in (a) and (b), the introduction of the CeO2 loading layer did not affect the HER activity of Pt. The CeO2 loading layer greatly reduced the dissolution of Pt active species in an alkaline environment. The prepared Pt:CeO2 / FTO electrode achieved long-term electrocatalytic water splitting to produce hydrogen under alkaline conditions. Furthermore, the addition of H2PtCl6 to the test solution further enhanced the effect. . The Pt active species were successfully introduced into the 6H2O solution. Through a self-healing process of leaching and redeposition of the Pt catalytic active centers, the Pt:CeO2 catalyst achieved high efficiency and stability. Ultimately, using these two methods, 100 hours of electrocatalytic water splitting for hydrogen production was achieved during the test.

[0059] As can be seen from the above embodiments, the method for preparing a highly stable alkaline HER catalyst provided by the present invention utilizes a dual-source electron beam evaporation deposition system to prepare a Pt:CeO2 catalytic layer film, thereby introducing CeO2 as a Pt support layer; then, Pt active species are added to the test solution, and through the self-healing process of leaching-redeposition of Pt catalytic active centers, the high efficiency and stability of the Pt:CeO2 catalyst are achieved, ultimately realizing the electrocatalytic water splitting to hydrogen production using a highly stable alkaline HER catalyst.

[0060] It is understood that this invention has been described through some embodiments, and those skilled in the art will recognize that various changes can be made to these features and embodiments without departing from the spirit and scope of this invention. Non-essential improvements and adjustments made to this invention by those skilled in the art based on the content of this invention should still fall within the protection scope of this invention.

Claims

1. A method for preparing a highly stable alkaline HER catalyst, characterized in that, Includes the following steps: Step 1: Clean and dry the fluorine-doped tin oxide conductive glass; Step 2: An Ag conductive thin film layer is deposited in the first region of the cleaned fluorine-doped tin oxide conductive glass substrate using electron beam deposition. Step 3: Using dual-source electron beam deposition, a Pt:CeO2 thin film layer is deposited in the second region on the fluorine-doped tin oxide conductive glass substrate treated in step 2. The second region does not overlap with the first region, and CeO2 is used as a load layer for Pt to prevent Pt from falling off in alkaline solution. Step 4: Weld the conductive wire to the Ag conductive film layer obtained in Step 2 to form an ohmic contact, and encapsulate it to obtain the Pt:CeO2 / FTO electrode; Step 5: Prepare an alkaline test solution containing Pt active species. During the electrocatalytic water splitting process, the active center of the catalyst is self-repaired through the leaching and redeposition of Pt species.

2. The preparation method according to claim 1, characterized in that, In step 2, a first region is defined by a mask, and the deposition rate of the Ag conductive thin film layer is 1 to 5 Å / s, with a deposition thickness of 2 µm.

3. The preparation method according to claim 1, characterized in that, In step 3, the first region is blocked by a mask to define the second region. The deposition rate of Pt is 0.1 Å / s and the deposition thickness is 30 Å. The deposition rate of CeO2 is 0.15-0.25 Å / s and the deposition thickness is 45-75 Å.

4. The preparation method according to claim 1, characterized in that, In step 5, the alkaline test solution containing Pt active species is a 1.0 mol / L KOH solution containing H2PtCl6. . 6H₂O, its concentration is 8.7 × 10⁻⁶ -5 mol / L.

5. A highly stable basic HER catalyst prepared by the method according to any one of claims 1 to 4, characterized in that, include: Fluorine-doped tin oxide conductive glass substrate; An Ag conductive thin film layer is formed on the first region of the fluorine-doped tin oxide conductive glass substrate. The Ag conductive film layer is connected to a wire and has an ohmic contact with the conductive part. A Pt:CeO2 thin film layer is formed on the second region of the fluorine-doped tin oxide conductive glass substrate, and the second region does not overlap with the first region. The Pt:CeO2 thin film layer serves as a catalyst layer, and Pt is uniformly doped into the CeO2 thin film in the Pt:CeO2 thin film layer. The CeO2 thin film layer also serves as a support layer to prevent Pt from falling off in alkaline solutions.

6. The highly stable alkaline HER catalyst according to claim 5, characterized in that, In the CeO2 thin film, Pt is uniformly doped and exists in the zero valence state.

7. A method for using the highly stable alkaline HER catalyst as described in claim 5 or 6 in an alkaline electrolyte for electrocatalytic water splitting to produce hydrogen, characterized in that, A highly stable alkaline HER catalyst was used as the cathode and placed in an alkaline KOH electrolyte containing Pt active species to carry out an electrocatalytic water splitting reaction. During the reaction, the active center of the catalyst was self-repaired through the leaching and redeposition of Pt species.

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