Cr-doped cobalt selenide-based electrolyzed water catalyst and preparation method thereof
By doping CoSe2 with Cr, a Crx-CoSe2 catalyst was prepared, which solved the problems of high cost and poor stability of precious metal catalysts, and achieved a high-efficiency and low-cost water electrolysis catalytic effect, which is suitable for industrial applications.
Patent Information
- Application Number
- CN202511001224.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-21
- Publication Date
- 2025-12-12
AI Technical Summary
Existing precious metal catalysts such as Pt/C suffer from high cost and poor stability in water electrolysis, especially in high potential and strong oxidizing environments, making it difficult to meet industrial requirements.
The Cr-doped cobalt selenide-based water electrolysis catalyst Crx-CoSe2 is prepared by doping CoSe2 with Cr to increase the specific surface area, optimize the electronic structure, improve the exposure of active sites and material stability. The preparation method includes hydrothermal reaction and calcination steps.
The activity and stability of the catalyst were significantly improved, the cost was reduced, and it has the potential for industrial application. The Cr-doped CoSe2 catalyst exhibits high catalytic activity and long lifetime in alkaline environment.
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Figure CN121110083A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to water electrolysis catalysts, and more particularly to a Cr-doped cobalt selenide-based water electrolysis catalyst and its preparation method. Background Technology
[0002] Water electrolysis technology, as a key pathway for green energy transformation, has the core value of synergistically integrating with renewable energy power generation systems. This technology directly produces hydrogen by electrochemically splitting water molecules, breaking through the dependence of traditional hydrogen production processes on fossil fuels or biomass feedstocks and constructing a zero-carbon cycle system from water to hydrogen. However, limited by the kinetic barriers of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), significant energy loss is generally observed during electrolysis, typically manifested as a high overpotential. Therefore, current technological breakthroughs focus on the innovative optimization of electrocatalyst systems: on the one hand, improving catalytic efficiency through microstructure design and active site regulation; on the other hand, striving to replace noble metal catalysts (such as platinum and iridium oxides) with transition metal-based materials such as iron, nickel, and cobalt. These non-noble metal catalysts not only significantly reduce material costs, but some composite catalysts even exhibit activity and stability surpassing traditional noble metal catalysts in specific electrolyte environments.
[0003] The mainstream catalysts in the electrocatalytic HER field are mainly Pt / C. Although these materials exhibit excellent catalytic activity, their inherent defects significantly limit their practical applications. On the one hand, the scarcity of precious metals and their extremely high mining costs lead to expensive catalysts; on the other hand, long-term operation in high-potential and strong oxidizing environments can easily cause structural instability or dissolution of active components, making it difficult to meet industrial requirements in terms of stability.
[0004] To overcome the bottleneck of dependence on precious metals, researchers have recently turned their attention to non-precious metal systems that are abundant in resources and inexpensive. Metal selenides are a class of electrocatalytic materials with excellent conductivity and high physical density. Selenides possess unique catalytic properties stemming from their special electronic structure. The d orbitals of metal atoms and the s / p orbitals of selenium form a strong synergistic effect through electronic hybridization, thereby optimizing the crystal field effect and charge transport capacity of the material. These compounds have narrow band gaps, which facilitate electron excitation, high active site density, and accelerate reaction kinetics. They also possess corrosion-resistant structures, especially in alkaline media, and are low-cost, demonstrating significant competitiveness in the field of catalysis and considered a crucial breakthrough for replacing precious metal catalytic systems.
[0005] Cobalt selenide (CoSe2) has become a highly potential candidate material and triggered a research boom due to its high catalytic efficiency and lasting stability during the electrolysis of water. Among numerous non-precious metal compounds, CoSe2 features low cost, easy synthesis, and high stability in alkaline solutions. However, due to insufficient exposure of active sites, the catalytic activity of pure CoSe2 is relatively low. Summary of the Invention
[0006] Object of the Invention: The object of the present invention is to provide a Cr-doped cobalt selenide-based electrolytic water catalyst with low cost, high activity, and high stability.
[0007] Another object of the present invention is to provide a preparation method of the above catalyst.
[0008] Technical Solution: The chemical formula of the Cr-doped cobalt selenide-based electrolytic water catalyst described in the present invention is Cr x -CoSe2, 0.1 < x < 0.4, and the particle size of the catalyst is 6 - 70 μm.
[0009] The preparation method of the catalyst described in the present invention includes the following steps:
[0010] (1) Clean the nickel foam substrate to obtain pretreated nickel foam;
[0011] (2) Add Co(NO3)2·6H2O, Cr(NO3)3·9H2O, and CO(NH2)2 into water in sequence and stir until all solids are dissolved;
[0012] (3) Place the solution obtained in step (2) into a reaction kettle inserted with the pretreated nickel foam for hydrothermal reaction to obtain a precursor;
[0013] (4) Calcinate the precursor and selenium to obtain the catalyst.
[0014] Preferably, the molar ratio of the fed Co(NO3)2·6H2O and Cr(NO3)3·9H2O in step (2) is 1:0.25.
[0015] Preferably, the hydrothermal reaction temperature in step (3) is 120 - 160 °C, more preferably 150 °C; the hydrothermal reaction time is 11 - 13 h, more preferably 12 h.
[0016] Preferably, the selenium in step (4) is powder.
[0017] Preferably, the mass feeding ratio of CO(NH2)2 in step (2) and selenium powder in step (4) is 1:1.5 - 1:2.5, more preferably 1:2.
[0018] Preferably, the calcination temperature in step (4) is 250-350℃, more preferably 300℃; and the calcination time is 1-3h, more preferably 2h.
[0019] Preferably, the calcination is carried out in a tube furnace, with the precursor and selenium powder placed downstream and upstream of the quartz tube, respectively.
[0020] Preferably, the heating rate during the calcination process is 3-6℃ / min, and more preferably 5℃ / min.
[0021] Invention Principle: This invention aims to provide a cobalt selenide-based water electrolysis catalyst by doping CoSe2 with Cr. Cr's lattice distortion or porous structure increases the specific surface area of CoSe2, thereby exposing more active sites and enhancing electrolyte contact. Cr can improve the material's conductivity by reducing charge transfer resistance, accelerating electron migration from active sites to the electrode, and improving reaction kinetics. Cr doping may optimize the adsorption strength of intermediates (such as *OOH) by adjusting the d-orbital electron distribution of Co, thus approaching the Sabatier optimum. Cr doping promotes surface reconstruction of CoSe2, generating highly catalytically active CoOOH crystals at lower potentials, contributing to improved performance. Cr doping may inhibit selenium loss or structural collapse of CoSe2 in alkaline environments, improving catalyst stability and extending catalyst lifetime.
[0022] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) By doping Cr into CoSe2, the present invention exposes more active sites on the catalyst and enhances electrolyte contact, optimizes the electronic structure of the catalyst, and improves its intrinsic catalytic activity; (2) The raw materials of this method are widely available and inexpensive, and the resulting catalyst is conducive to enhancing the activity and stability of electrode hydrogen evolution, and has the prospect of industrial application; (3) The Cr-doped CoSe2 catalyst has high stability and long life. Attached Figure Description
[0023] Figure 1 The image shows the SEM image of the catalyst prepared in Example 1.
[0024] Figure 2 The electrochemical test results are for each catalyst;
[0025] Figure 3 The catalyst prepared in Example 1 was at 100 mA / cm 2 The it curve at current density. Detailed Implementation
[0026] The technical solution of the present invention will be further described below with reference to the embodiments.
[0027] Example 1
[0028] The Cr-doped cobalt selenide-based water electrolysis catalyst of this invention is Cr 0.25 -CoSe2, with a particle size of 6-70μm.
[0029] The preparation method of the Cr-doped cobalt selenide-based water electrolysis catalyst of the present invention includes the following steps:
[0030] (1) The surface of nickel foam (NF) substrate was cleaned by stepwise ultrasonic treatment. The nickel foam was placed in different media in the order of acetone, 3M hydrochloric acid, ethanol and deionized water for ultrasonic treatment, and each medium was treated for 15 min to effectively remove contaminants and oxide layers attached to the surface of the nickel foam. Subsequently, the sample was transferred to a constant temperature vacuum drying device and dried continuously at 60±2℃ for 180 min to obtain pretreated nickel foam.
[0031] (2) Add 1 mmol Co(NO3)2·6H2O, 0.25 mmol Cr(NO3)3·9H2O and 0.2 g CO(NH2)2 to 30 mL of deionized water in sequence, and place on a magnetic stirrer and stir at room temperature for 30 min until the solid is completely dissolved.
[0032] (3) The solution obtained in step (2) was transferred to the polytetrafluoroethylene (PTFE) liner of a 50 mL reactor. The pretreated nickel foam obtained in step (1) was inserted obliquely into the PTFE liner, and the reactor was subjected to a hydrothermal reaction at 150 °C for 12 h in a forced-air drying oven. After natural cooling, the sample was washed multiple times with deionized water at room temperature, and then dried in a vacuum drying oven at 60 °C for 4 h to obtain the precursor Cr. 0.25 -Co(OH)2.
[0033] (4) The obtained precursor Cr 0.25 -Co(OH)₂ and 0.4 g of selenium powder were placed downstream and upstream of the quartz tube in a tube furnace, respectively, and the temperature was increased to 300 °C at a rate of 5 °C / min under nitrogen atmosphere. The mixture was calcined for 2 h, and after the reaction was completed, it was naturally cooled to room temperature to obtain the Cr-doped cobalt selenide-based catalyst Cr. 0.25 -CoSe2. The purpose of calcination is to sublimate the selenium powder through calcination and allow it to come into contact with the subsequent precursor and undergo a doping reaction under the action of gas in the tube furnace. The two cannot come into direct contact, which is usually the conventional operation method for calcination doping.
[0034] Example 2
[0035] The similarities between this embodiment and Embodiment 1 will not be repeated here. The difference is that the amount of Cr(NO3)3·9H2O added in step (2) is 0.1 mmol.
[0036] Example 3
[0037] The similarities between this embodiment and Embodiment 1 will not be repeated here. The difference is that the amount of Cr(NO3)3·9H2O added in step (2) is 0.4 mmol.
[0038] Example 4
[0039] The similarities between this embodiment and Embodiment 1 will not be repeated here. The difference is that the temperature of the hydrothermal reaction in step (3) is 120°C.
[0040] Example 5
[0041] The similarities between this embodiment and Embodiment 1 will not be repeated here. The difference is that the temperature of the hydrothermal reaction in step (3) is 160°C.
[0042] Comparative Example 1
[0043] The similarities between this comparative example and Example 1 will not be repeated here. The difference is that the amount of Cr(NO3)3·9H2O added in step (2) is 0.05 mmol.
[0044] Comparative Example 2
[0045] The similarities between this comparative example and Example 1 will not be repeated here. The difference is that the amount of Cr(NO3)3·9H2O added in step (2) is 0.5 mmol.
[0046] Comparative Example 3
[0047] The similarities between this comparative example and Example 1 will not be repeated here. The difference is that the temperature of the hydrothermal reaction in step (3) is 100°C.
[0048] Comparative Example 4
[0049] The similarities between this comparative example and Example 1 will not be repeated here. The difference is that the temperature of the hydrothermal reaction in step (3) is 180°C.
[0050] Comparative Example 5
[0051] The similarities between this comparative example and Example 1 will not be repeated here. The difference is that the amount of Cr(NO3)3·9H2O added in step (2) is 0.
[0052] The catalyst obtained in Example 1 was analyzed by XRD. Besides the main peak of NF, the weak peaks matched the (210), (211), and (311) crystal planes of cubic CoSe2, confirming the formation of CoSe2. Furthermore, compared to CoSe2, Cr... 0.25The peak of -CoSe2 shows a slight leftward shift of about 0.1°, which is due to the fact that the atomic radius of Cr is slightly larger than that of Co, indicating that Cr has been successfully incorporated into the lattice of CoSe2. 0.25 The successful preparation of -CoSe2 provides a basis for this.
[0053] The catalyst obtained in Example 1 was analyzed by SEM, as follows: Figure 1 As shown in the figure, the catalyst exhibits a particulate morphology with a particle size of 6-70 μm. The overall structure is relatively loose, and the smaller catalyst particles have a larger specific surface area, which is more conducive to the catalytic reaction.
[0054] Electrochemical tests were performed on the catalysts prepared in Examples 1-5 and Comparative Examples 1-5 using a three-electrode system. The results are as follows: Figure 2 As shown. The specific experimental procedure is as follows: The nickel foam substrate loaded with catalytic material was precisely cut to obtain a size of 1×1×0.15cm. 3 Specifications for the sample, controlling the effective working electrode area to be 1 cm². 2 Under constant temperature of 25℃, a test system consisting of a Pt sheet as the counter electrode and Hg / HgO as the reference electrode was constructed using 1M KOH solution as the electrolyte. The LSV curves of these catalysts can be observed at a current density of 10 mA cm⁻¹. -2 When the amount of Cr(NO3)3·9H2O added was 0.25, 0.1, and 0.4 mmol (Examples 1-3), the overpotentials of the catalyst were 56 mV, 89 mV, and 115 mV, respectively. However, without the addition of Cr (Comparative Example 5), the overpotential of the catalyst reached as high as 170 mV. This demonstrates that the presence of Cr doping is beneficial to the HER reaction. The introduction of Cr significantly improves the electronic coupling at the two-phase interface, thereby accelerating the transport of hydrogen intermediates. Furthermore, during the HER reaction, due to the presence of Cr... 3+ Cr produced by partial oxidation 6+ It possesses strong electron absorption capabilities, which can effectively stabilize the high-valence active sites of the catalyst. Furthermore, by varying the hydrothermal temperature, it was found that the catalyst exhibits optimal activity at a hydrothermal temperature of 150°C (Example 1), which is more conducive to the occurrence of the catalytic reaction.
[0055] The performance parameters of catalysts play a decisive role in electrocatalytic reactions, especially in industrial applications. The long-term operational capability of catalytic materials is a key indicator for evaluating their overall performance. The accelerated durability of the catalyst obtained in Example 1 was evaluated using the chronopotential method, and the results are as follows: Figure 3 As shown. The evaluation method is as follows: 100 mA cm⁻¹ is applied to a 1 mol / L KOH electrolyte. -2The catalyst was operated at a constant current density for 50 hours. Experimental data showed that the potential fluctuation of the catalyst was less than 2% throughout the entire test period, indicating that the material has significant structural stability and anti-polarization properties. This excellent durability demonstrates that the catalyst prepared in Example 1 has good potential for industrial application in industrial-grade water electrolysis devices.
Claims
1. A Cr-doped cobalt selenide-based water electrolysis catalyst, characterized in that, The chemical formula of the catalyst described is Cr x -CoSe2, where 0.1 < x < 0.4, and the particle size of the catalyst is 6 - 70 μm.
2. A method for preparing the catalyst according to claim 1, characterized in that, Includes the following steps: (1) Clean the nickel foam substrate to obtain pretreated nickel foam; (2) Add Co(NO3)2·6H2O, Cr(NO3)3·9H2O and CO(NH2)2 to water in sequence and stir until all the solids are dissolved; (3) The solution obtained in step (2) is placed in a reactor containing pretreated nickel foam and subjected to a hydrothermal reaction to obtain the precursor; (4) The precursor and selenium are calcined to obtain the catalyst.
3. The preparation method according to claim 2, characterized in that, The molar ratio of Co(NO3)2·6H2O and Cr(NO3)3·9H2O in step (2) is 1:0.23-0.
28.
4. The preparation method according to claim 2, characterized in that, The hydrothermal reaction temperature in step (3) is 120-160℃, and the hydrothermal reaction time is 11-13h.
5. The preparation method according to claim 2, characterized in that, The hydrothermal reaction temperature described in step (3) is 145-155℃.
6. The preparation method according to claim 2, characterized in that, The selenium mentioned in step (4) is in powder form.
7. The preparation method according to claim 6, characterized in that, The mass ratio of CO(NH2)2 in step (2) to selenium powder in step (4) is 1:1.5-1:2.
5.
8. The preparation method according to claim 2, characterized in that, The calcination temperature in step (4) is 250-350℃, and the calcination time is 1-3h.
9. The preparation method according to claim 6, characterized in that, The calcination is carried out in a tube furnace, with the precursor and selenium powder placed downstream and upstream of the quartz tube, respectively.
10. The preparation method according to claim 2, characterized in that, The heating rate during the calcination process is 3-6℃ / min.