Preparation method of cobalt-based oxide phosphide heterojunction catalyst based on hydrogen evolution reaction in alkaline environment
By preparing CoMoO4@CoZn-P/NF heterostructure materials, the problems of insufficient conductivity and active sites of electrocatalysts in alkaline environments were solved, achieving a highly efficient and stable hydrogen evolution reaction with performance close to that of noble metal catalysts, making it suitable for large-scale production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2026-01-30
- Publication Date
- 2026-04-10
AI Technical Summary
Existing electrocatalysts suffer from insufficient conductivity, insufficient active sites, and complex synthesis processes with poor reproducibility in alkaline environments during electrochemical water splitting, which limits their application in hydrogen production through water electrolysis.
A self-supporting substrate strategy was adopted to prepare CoMoO4@CoZn-P/NF heterostructure materials by hydrothermal method and chemical vapor deposition method, constructing a hierarchical structure of nanosheets and nanorods to enhance electronic coordination effect and optimize electrochemical performance.
It achieves a highly efficient and stable hydrogen evolution reaction under alkaline conditions, with significantly improved catalytic activity, low overpotential, good stability, and performance close to that of commercial Pt/C catalysts, making it suitable for large-scale production.
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Figure CN121826780A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrolysis of water and hydrogen evolution reaction catalysis technology, specifically relating to a method for preparing a cobalt-based oxide phosphide heterojunction catalyst based on hydrogen evolution reaction in an alkaline environment. Background Technology
[0002] Addressing the urgent need to mitigate the environmental damage caused by the widespread use of fossil fuels necessitates prioritizing clean and renewable energy in the 21st century. A major challenge facing electrochemical technologies is improving the efficiency of processes that utilize renewable energy to convert air molecules (such as water, carbon dioxide, and nitrogen) into valuable products (such as hydrogen, hydrocarbons, oxygenates, and ammonia). Traditional hydrogen production methods, such as steam methane reforming, rely on fossil fuels and generate greenhouse gas emissions. Electrochemical water splitting, consisting of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), plays a crucial role in renewable energy applications because it can produce high-purity hydrogen with zero carbon emissions. However, the commercialization of this technology is hampered by challenges such as low current density, high overpotential, and alkaline instability. Therefore, developing efficient and economical electrocatalysts to improve the performance of current energy conversion devices is essential. Currently, commercial water electrolysis relies entirely on precious metals, such as Pt-C for HER and RuO2 and IrO2 for OER. However, the limited availability of Pt, Ir, and Ru restricts the widespread application of such technologies. Therefore, there is an urgent need to develop cost-effective, energy-efficient, and robust transition metal-based electrocatalysts.
[0003] Transition metal-based electrocatalysts, including metal oxides, nitrides, sulfides, and hydroxides, have attracted attention as potential HER electrocatalysts due to their availability, catalytic activity, and simple synthesis methods. Notably, nanostructured metal oxides are particularly promising candidates due to their global abundance, nanoscale structural adaptability, and electrocatalytic efficiency exhibited in various energy conversion systems. Among these materials, ABO4-structured compounds have garnered attention due to their bimetallic composition and customizable structure, where A represents a Group VIII transition metal (such as Co or Fe) and B represents a Group VII transition metal (such as Mo or Cr). Molybdenum, with its body-centered cubic structure, exhibits superior alkaline stability and catalytic activity for electrochemical water splitting.
[0004] Bimetallic oxides generally outperform monometallic oxides in electrocatalytic performance, primarily due to enhanced conductivity and intermetallic synergistic effects, which promote efficient electron transfer. As a representative bimetallic oxide, CoMoO4 has emerged as a potential material for HER (hydrochemical reaction), leveraging its high density of electroactive sites, large surface area, and robust structural stability. However, its application in HER remains limited by sluggish reaction kinetics and insufficient affinity for key intermediates. Therefore, engineering CoMoO4-based electrocatalysts to simultaneously optimize HER function and achieve efficient water splitting is both a crucial scientific goal and a formidable technological challenge.
[0005] Currently, improvements to CoMoO4 primarily focus on optimizing its electronic structure and constructing composite systems. Phosphating CoMoO4 is the most direct modification method. The introduction of phosphorus effectively modulates the electron cloud density of molybdenum (Mo) and cobalt (Co) sites within the material, reducing its hydrogen adsorption free energy and significantly improving the overall conductivity of the material, thereby improving reaction kinetics. Coupled CoMoO4 with other semiconductor materials (such as Co2Mo3O8, metal phosphides, etc.) to construct heterojunctions is a more efficient strategy. A built-in electric field is formed at the heterojunction interface, driving the directional redistribution and rapid transfer of charges. This not only optimizes the adsorption strength of hydrogen intermediates but also effectively promotes the key water dissociation step under alkaline conditions, thus accelerating the reaction at multiple stages. Based on phosphorus doping, introducing second or even third elements such as iron (Fe), boron (B), and zinc (Zn) for co-doping can achieve a "synergistic doping" effect. This approach allows for more precise control of the electronic state of the active centers, thereby systematically optimizing the reaction energy barriers of multiple steps such as water molecule adsorption, dissociation, and hydrogen desorption. Furthermore, by growing CoMoO4-P nanosheets or nanorod arrays in situ on a three-dimensional conductive substrate (such as nickel foam), the exposure of active sites can be significantly increased, the mass transfer process can be enhanced, and the binding force between the catalyst and the substrate can be strengthened, thereby improving the stability of the overall structure.
[0006] To realize the practical application of this catalyst system, the following key bottlenecks still need to be overcome: the material itself suffers from insufficient conductivity, and the intrinsic catalytic activity of its active sites still needs further improvement. Furthermore, the preparation of high-performance catalysts often relies on multi-step, complex synthesis processes, resulting in poor reproducibility and difficulty in large-scale production. In addition, the surface reconstruction mechanism of the catalyst during operation is complex, and its long-term electrochemical stability still needs to be improved. Summary of the Invention
[0007] To address the aforementioned problems, this invention provides a method for preparing a cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction (HER) in an alkaline environment. This invention employs a self-supporting substrate strategy, using a hydrothermal method and chemical vapor deposition to prepare a CoMoO4@CoZn-P / NF heterostructure material. This heterostructure catalyst exhibits highly significant HER activity and excellent stability in 1 M KOH solution. This invention has crucial application value for electrochemical alkaline hydrogen evolution.
[0008] The technical solution of the present invention is as follows: The preparation method of cobalt-based oxide phosphide heterojunction catalysts based on hydrogen evolution reaction in an alkaline environment includes the following steps: Step S1: CoMoO4 / NF nanorods are synthesized on a nickel foam substrate via a hydrothermal reaction; Step S2: Introduce cobalt-molybdenum metal oxides by loading Co(OH)2 and Zn(OH)2 onto CoMoO4 / NF nanorods to form CoMoO4@CoZn-LDH / NF; Step S3: Synthesize the cobalt-based oxide phosphide heterojunction catalyst CoMoO4@CoZn-P / NF through phosphating reduction and ion exchange.
[0009] Preferably, in step S1, the nickel foam substrate is pretreated; the pretreatment includes the removal of surface oxides and oil stains from the nickel foam substrate, specifically including: immersing the nickel foam in 1-5 M HCl, water, and ethanol in sequence for ultrasonic cleaning, and then placing the pretreated nickel foam in anhydrous ethanol for later use.
[0010] Preferably, the synthesis of CoMoO4 / NF nanorods in step S1 specifically includes the following steps: S1.1. Cobalt salt and molybdenum salt are added to water in sequence to form a mixed solution; S1.2 The stirred solution is clear and transparent; S1.3 Transfer the solution to the liner of the reactor and place the pretreated nickel foam inside. Then, place the sealed reactor into an electric heating oven for the reaction. S1.4 After the reaction is complete, the product is naturally cooled to room temperature, washed multiple times with ethanol and water, and dried in an electric heating oven to obtain CoMoO4 / NF nanorods.
[0011] Preferably, the cobalt salt is one or a mixture of two or more of cobalt nitrate, cobalt chloride, and cobalt acetate.
[0012] Preferably, the molybdenum salt is one or a mixture of two of ammonium molybdate and sodium molybdate.
[0013] Preferably, the mass ratio of cobalt salt to molybdenum salt in S1.1 is (270~310):(290~330).
[0014] Preferably, the reaction temperature described in S1.3 is 130 ℃~170 ℃, and the reaction time is 3~7 h.
[0015] Preferably, the drying temperature described in S1.4 is 40 ℃ to 80 ℃.
[0016] Preferably, the synthesis of CoMoO4@CoZn-LDH / NF in S2 includes the following steps: S2.1 Immerse CoMoO4 nanorods in an aqueous solution containing cobalt salt, zinc salt, urea and ammonium fluoride; S2.2 Transfer to the Teflon liner of the high-pressure reactor, place the sealed reactor in an electric heating oven, and allow it to cool naturally to room temperature after the hydrothermal reaction. S2.3. The CoMoO4@CoZn-LDH / NF was obtained by washing several times with ethanol and water and drying overnight in an electric heating oven.
[0017] Preferably, the zinc salt is one or a mixture of two or more of zinc nitrate, zinc chloride, and zinc acetate.
[0018] Preferably, the mass ratio of cobalt salt, zinc salt, urea, and ammonium fluoride in S2.1 is (270~310):(280~320):(220-260):(60-100).
[0019] Preferably, the reaction temperature described in S2.2 is 100 ℃~140 ℃, and the reaction time is 10~14 h.
[0020] Preferably, the drying temperature described in S2.3 is 40 ℃ to 80 ℃.
[0021] Preferably, the synthesis of CoMoO4@CoZn-P / NF in S3 includes the following steps: S3.1, CoMoO4@ CoZn-LDH / NF is placed downstream of the tube furnace, and a ceramic boat containing sodium hypophosphite is placed downstream; S3.2. Maintain the temperature at a fixed rate for a period of time, and remove the tube furnace after it has cooled to room temperature. S3.3 Washed several times with ethanol and water, and finally dried overnight in an electric heating oven. After natural cooling, a black CoMoO4@CoZn-P / NF catalyst was obtained.
[0022] Preferably, in step S3.1, the amount of sodium hypophosphite added is 100-150 mg / cm³. 2 Nickel foam substrate.
[0023] Preferably, the calcination temperature in S3.2 is 200 ℃~500 ℃, the heating rate is 1-5 ℃ / min, and the calcination time is 1~3 h.
[0024] Preferably, the drying temperature described in S3.3 is 40 ℃ to 80 ℃.
[0025] Compared with the prior art, the present invention has the following technical effects: The CoMoO4@CoZn-P / NF heterojunction catalyst of this invention possesses a hierarchical structure of nanosheets and nanorods, abundant active sites, and excellent mass transfer. A stable framework of CoMoO4 / NF is constructed using nickel foam as a template and an induced etching method, providing an extremely stable three-dimensional structure for the overall material and contributing to its excellent stability. By rationally adjusting the Co / Zn ratio and forming a Zn3P2 and CoP heterostructure on CoMoO4 / NF through phosphating, the coordination effect between electrons is enhanced, increasing the material's conductivity and optimizing its electrochemical performance. Attached Figure Description
[0026] Figure 1 This is an X-ray diffraction pattern of the cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to the present invention. Figure 2 These are scanning electron microscope (SEM) images of the cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to the present invention. Among them, (a) and (b) are SEM images of CoMoO4 / NF, (c) and (d) are SEM images of CoMoO4@CoZn-LDH / NF, and (e) and (f) are SEM images of CoMoO4@CoZn-P / NF. Figure 3 These are high-resolution electron microscope images of the cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to the present invention. Among them, (a) is a TEM image of CoMoO4@CoZn-P / NF, (b) and (c) are HRTEM images of CoMoO4@CoZn-P / NF, and (d)~(h) are EDS elemental mapping images of CoMoO4@CoZn-P / NF. Figures 4-8 This is the XPS spectrum of the cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to the present invention, wherein, Figure 4 XPS spectra of CoMoO4-P / NF, CoZn-P / NF, and CoMoO4@CoZn-P / NF. Figures 5-8 High-resolution XPS spectra of Co2p, Mo 3d, Zn 2p, and P 2p, respectively; Figure 9The graphs show the hydrogen evolution performance evaluation of the cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to the present invention. In the graphs, (a) is the LSV curve, (b) is the overpotential curve, (c) is the Tafel slope curve, and (d) is the impedance curve. Figure 10 This is a comparison diagram of the surface active area of the cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to the present invention and the preparation method. Figure 11 The figure shows the hydrogen evolution stability test results of the cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to the present invention. In this figure, (a) is the 1t stability curve and (b) is the cycle stability curve. Figure 12 This is a comparison chart showing the performance of the cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment, as described in this invention, with catalysts from recently published articles. Detailed Implementation
[0027] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.
[0028] Example 1: Preparation of cobalt-based oxide phosphide heterojunction catalyst CoCl2·6H2O (270 mg) and (NH4)6Mo7O 24 ·4H2O (290 mg) was dissolved in 30 ml of deionized water, and the solution became clear and transparent after stirring. The solution was transferred to the liner of a reaction vessel, and pretreated nickel foam was placed inside. The sealed reaction vessel was placed in an electric heating oven and reacted at 130 °C for 3 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature, washed several times with ethanol and water, and dried in an electric heating oven at 40 °C to obtain CoMoO4 / NF nanorods.
[0029] CoMoO4 / NF nanorods were immersed in a solution containing CoCl2·6H2O (270 mg), ZnCl2·6H2O (280 mg), CO(NH2)2 (220 mg), and NH4F (60 mg). The solution was transferred to a Teflon-lined high-pressure reactor, which was then placed in an electrically heated oven and reacted at 100 °C for 10 h. After the hydrothermal reaction, the mixture was allowed to cool naturally to room temperature. The nanorods were washed several times with ethanol and water and dried overnight in an electrically heated oven at 40 °C to obtain CoMoO4@CoZn-LDH / NF.
[0030] The hydrothermal product CoMoO4@CoZn-LDH / NF was collected, and 400 mg of sodium hypophosphite was placed in a porcelain boat. The CoMoO4@CoZn-LDH / NF was placed downstream of a tube furnace, and the porcelain boat containing sodium hypophosphite was placed upstream. High-temperature calcination was performed under an argon atmosphere at 200 °C, a heating rate of 1 °C / min, and a calcination time of 1 h to prepare CoMoO4@CoZn-P / NF. After the tube furnace cooled to room temperature, the catalyst was removed. It was washed several times with ethanol and water, and finally dried overnight in a 40 °C electrically heated oven. After natural cooling, a black CoMoO4@CoZn-P / NF catalyst was obtained.
[0031] Example 2: Preparation of Cobalt-based Oxide Phosphide Heterojunction Catalyst (CH3COO)2Co·4H2O (310 mg) and Na2MoO4·4H2O (330 mg) were dissolved in 30 ml of deionized water and stirred until the solution became clear and transparent. The solution was transferred to the liner of a reaction vessel, and pretreated nickel foam was placed inside. The sealed reaction vessel was placed in an electrically heated blast oven and reacted at 170 °C for 7 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature, washed several times with ethanol and water, and dried in an electrically heated blast oven at 80 °C to obtain CoMoO4 / NF nanorods.
[0032] CoMoO4 / NF nanorods were immersed in a solution containing Co(CH3COO)2·4H2O (310 mg), Zn(CH3COO)2·2H2O (320 mg), CO(NH2)2 (260 mg), and NH4F (100 mg). The solution was transferred to a Teflon-lined high-pressure reactor, which was then placed in an electrically heated oven and reacted at 140 °C for 14 h. After the hydrothermal reaction, the mixture was allowed to cool naturally to room temperature. The nanorods were washed several times with ethanol and water and dried overnight in an electrically heated oven at 80 °C to obtain CoMoO4@CoZn-LDH / NF.
[0033] The hydrothermal product CoMoO4@CoZn-LDH / NF was collected, and 600 mg of sodium hypophosphite was placed in a porcelain boat. The CoMoO4@CoZn-LDH / NF was placed downstream of a tube furnace, while the porcelain boat containing sodium hypophosphite was placed upstream. High-temperature calcination was performed under an argon atmosphere at 500 °C, a heating rate of 5 °C / min, and a calcination time of 3 h to prepare CoMoO4@CoZn-P / NF. After the tube furnace cooled to room temperature, the catalyst was removed. It was washed several times with ethanol and water, and finally dried overnight in an 80 °C electric heating oven. After natural cooling, a black CoMoO4@CoZn-P / NF catalyst was obtained.
[0034] Example 3: Preparation of Cobalt-based Oxide Phosphide Heterojunction Catalyst Co(NO3)2·6H2O (291 mg) and (NH4)6Mo7O 24 • 4H2O (309 mg) was dissolved in 30 ml of deionized water, and the solution was stirred until clear and transparent. The solution was transferred to the liner of the reaction vessel, and pretreated nickel foam was placed inside. The sealed reaction vessel was then placed in an electric heating oven and reacted at 150 °C for 5 h. After the reaction was completed, the mixture was naturally cooled to room temperature, washed multiple times with ethanol and water, and dried in a 60 °C electrically heated oven to obtain CoMoO4 / NF nanorods.
[0035] CoMoO4 / NF nanorods were immersed in a solution containing Co(NO3)2·6H2O (291 mg), Zn(NO3)2·6H2O (298 mg), CO(NH2)2 (240 mg), and NH4F (74 mg). The solution was transferred to a Teflon-lined high-pressure reactor, which was then placed in an electrically heated oven and reacted at 120 °C for 12 h. After the hydrothermal reaction, the mixture was allowed to cool naturally to room temperature. The nanorods were washed several times with ethanol and water and dried overnight in an electrically heated oven at 60 °C to obtain CoMoO4@CoZn-LDH / NF.
[0036] The hydrothermal product CoMoO4@CoZn-LDH / NF was collected, and 500 mg of sodium hypophosphite was placed in a porcelain boat. The CoMoO4@CoZn-LDH / NF was placed downstream of a tube furnace, and the porcelain boat containing sodium hypophosphite was placed upstream. High-temperature calcination was performed under an argon atmosphere at 350 °C, a heating rate of 2 °C / min, and a calcination time of 2 h to prepare CoMoO4@CoZn-P / NF. After the tube furnace cooled to room temperature, the catalyst was removed. It was washed several times with ethanol and water, and finally dried overnight in a 60 °C electric heating oven. After natural cooling, a black CoMoO4@CoZn-P / NF catalyst was obtained.
[0037] Example 4 This embodiment, based on Example 3, details the morphology characterization and verification of the cobalt-based oxide phosphide heterojunction catalyst for hydrogen evolution reaction in an alkaline environment, specifically including: like Figure 1As shown, the chemical composition and crystal structure of the catalyst were tested by XRD. The three high-intensity diffraction peaks at 44.5, 51.8, and 76.3° were attributed to the nickel foam matrix. However, due to the strong diffraction peaks of the nickel foam matrix, the diffraction peak intensities of the material loaded on the nickel foam were significantly reduced. After logarithmic transformation of the XRD pattern, the diffraction peak at 23.3° corresponded to CoMoO4 (PDF#21–0868). After recording the XRD pattern, diffraction peaks at positions such as 35.3° and 31.3° corresponded to CoP (PDF#29–0497) and Zn3P2 (PDF#47–1441) materials, indicating that the CoMoO4@CoZn-P material had been successfully deposited on the nickel foam.
[0038] The CoMoO4 / NF, CoMoO4@CoZn-LDH / NF, and CoMoO4@CoZn-P / NF catalysts were tested using field emission scanning electron microscopy. Figure 2 As shown, the CoMoO4 / NF catalyst synthesized by hydrothermal reaction ( Figure 2 The surfaces of (a) and (b) exhibit a nanorod array structure, which is compactly arranged and has a smooth and flat surface.
[0039] After the second hydrothermal reaction, the nanorods on the surface of the CoMoO4@CoZn-LDH / NF catalyst are completely covered by nanosheet wrinkles, and the surface of the nanosheets is smooth and flat. Figure 2 (c) and (d) show that cobalt hydroxide and zinc hydroxide nanosheets were successfully grown.
[0040] After phosphating, the surface of the CoMoO4@CoZn-P / NF catalyst becomes rougher, exhibiting a hierarchical structure of nanosheets and nanorods. Figure 2 (e) and (f)).
[0041] High-resolution transmission electron microscopy (TEM) images of the CoMoO4@CoZn-P / NF catalyst, as shown below. Figure 3 As shown, Figure 3 As can be seen in (a), the catalyst consists of two parts: crystalline and amorphous. The two form a heterogeneous interface, which is beneficial for adjusting the electronic structure of the CoMoO4@CoZn-P / NF catalyst and promoting the adsorption and desorption process of intermediates in the electrocatalytic HER process.
[0042] The lattice fringe spacings of the crystalline form were 0.286 nm, 0.226 nm, and 0.197 nm, corresponding to the (021) crystal plane of CoMoO4, the (220) crystal plane of Zn3P2, and the (200) crystal plane of CoP, respectively, which is consistent with the XRD results. Analysis of these results indicates that the catalyst consists of two parts: crystalline CoZn-P and amorphous CoMoO4. Figure 3(d)~(h) indicates that the four elements Co, Mo, Zn and P are evenly distributed on the nanosheet.
[0043] This embodiment details the field emission scanning electron microscope (FET) images obtained from testing the CoMoO4 / NF, CoMoO4@CoZn-LDH / NF, and CoMoO4@CoZn-P / NF catalysts, demonstrating that the CoMoO4@CoZn-P / NF catalyst prepared in this application possesses high catalytic activity and stability.
[0044] like Figures 4-8 As shown, the surface chemical state of the catalyst has a significant impact on the HER catalytic effect. XPS was used to investigate the elemental composition and chemical state of the CoMoO4@CoZn-P / NF catalyst. The peaks of Co, Mo, Zn, and P in the full spectrum scan are shown below. Figure 4 Consistent with EDS results; like Figures 4-8 As shown, the role of CoZn-P composite CoMoO4 is further explained; the surface elemental chemical states of CoMoO4-P / NF, CoZn-P / NF and CoMoO4@CoZn-P / NF catalysts were tested by XPS.
[0045] Figure 4 The XPS survey spectrum of CoMoO4@CoZn-P / NF shows peaks for Mo, P, Co, and Zn orbitals. Figure 5 The image shows the XPS spectrum of the Co 2p region, which is composed of Co... 2+ Co 3+ The spectrum consists of two main peaks, along with other Co peaks, which originate from unreduced raw materials present on the surface due to exposure to air. Notably, compared to CoMoO4-P / NF, the Co peak in the CoMoO4@CoZn-P / NF heterojunction shifts to lower binding energies, indicating that the synergistic effect of CoP, CoMoO4, and Zn3P2 leads to a change in the electronic structure of Co. Similarly, the XPS spectrum in the Mo 3d region ( Figure 6 The active components are fixed as four types, including Mo derived from the high-valence state of CoMoO4. 6+ And Mo, which belongs to the low valence state 4+The Mo peak in the CoMoO4@CoZn-P / NF heterojunction shifted to a higher binding energy compared to the peak in pure CoMoO4-P / NF, demonstrating a change in the electronic structure of Mo and further proving a good synergistic effect between Zn3P2, CoP, and CoMoO4. Specifically, this indicates that electrons partially migrate from Mo to Co at the heterojunction interface, forming an electron-rich region around Co species and partially positively charged Mo species in the heterostructure. Therefore, confining P to the CoMoO4@CoZn-LDH / NF surface allows for the reconstruction of the electronic structures of CoP, Zn3P2, and CoMoO4, which is significant for improving the chemisorption capacity of CoMoO4@CoZn-P / NF materials for HER intermediates and further enhancing catalytic activity. Similarly, the Zn 2p peak in CoMoO4@CoZn-P / NF shifted to a lower binding energy compared to CoZn-P. Figure 7 ), while the P 2p peak ( Figure 8 The electrons shift towards higher binding energies, which further confirms the transfer of electrons from Mo and P to Zn and Co, indicating a strong synergistic effect in the heterostructure.
[0046] This embodiment details the CoMoO4@CoZn-P / NF catalyst, whose optimized surface chemical state significantly improves catalytic performance and stability. XPS analysis revealed that a heterostructure is formed between the phosphated CoZn-P and CoMoO4. This structure not only modulates the electronic structure of the catalyst but also optimizes the adsorption and desorption energies of reaction intermediates, thereby accelerating the HER kinetics.
[0047] Example 5 This embodiment, based on Example 3, describes in detail the hydrogen evolution catalytic activity of the cobalt-based oxide phosphide heterojunction catalyst for the hydrogen evolution reaction in an alkaline environment, specifically including: like Figure 9 As shown, the LSV curve after IR correction ( Figure 5 As shown in a), CoMoO4@CoZn-P / NF exhibits the best catalytic activity among the six materials. Figure 5 The study compared various materials at 10, 50, and 100 mA·cm⁻¹. -2 Overpotential at 10, 50, and 100 mA·cm⁻¹. CoMoO₄@CoZn-P / NF at 10, 50, and 100 mA·cm⁻¹ -2 The overpotentials at these locations were 17, 76, and 111 mV, respectively, which are lower than those of similar products at the same current density, indicating better catalytic activity. Importantly, compared with other electrocatalysts in the literature, CoMoO4@CoZn-P / NF exhibited better catalytic activity at 100 mA·cm⁻¹. -2The high overpotential exhibited indicates superior HER performance. Based on the obtained LSV curves, Tafel plots of CoMoO4@CoZn-LDH / NF, CoMoO4@CoZn-P / NF, CoMoO4 / NF, CoMoO4-P / NF, CoZn-LDH / NF, and CoZn-P / NF were derived, and their HER kinetics were investigated. Figure 5 The data in the middle section (c) shows that CoMoO4@CoZn-P / NF (44.6 mV·dec) -1 The Tafel slope of ) is lower than that of CoMoO4-P / NF (46.3 mV·dec) -1 ), CoZn-P / NF (54.6 mV·dec -1 ), CoMoO4 / NF (157.7 mV·dec -1 ), CoMoO4@CoZn-LDH / NF (157.2 mV·dec -1 ) and CoZn-LDH / NF (129.9 mV·dec -1 This demonstrates the optimal catalytic kinetics of HER with the aid of CoMoO4@CoZn-P / NF. Furthermore, Tafel plots further confirm that CoMoO4@CoZn-P / NF exhibits superior catalytic activity for HER compared to CoMoO4-P / NF and CoZn-P / NF alone.
[0048] Figure 5 The EIS data in the middle shows that CoMoO4@CoZn-P / NF can provide the lowest charge transfer resistance (Rct), which is lower than that of CoMoO4@CoZn-LDH / NF, CoMoO4 / NF, CoMoO4-P / NF, CoZn-LDH / NF, and CoZn-P / NF.
[0049] To investigate the reasons for the excellent HER activity of the CoMoO4@CoZn-P / NF catalyst, CV tests were conducted on the composite catalysts of CoMoO4@CoZn-LDH / NF, CoMoO4@CoZn-P / NF, CoMoO4 / NF, CoMoO4-P / NF, CoZn-LDH / NF, and CoZn-P / NF.
[0050] Based on the CV test results, such as Figure 10 As shown, the Cdl values of CoMoO4@CoZn-LDH / NF, CoMoO4 / NF, CoMoO4-P / NF, CoZn-LDH / NF, and CoZn-P / NF are 0.4, 0.95, 26.2, 0.5, and 20.6 mF·cm⁻¹, respectively. -2The Cdl value of CoMoO4@CoZn-P / NF is 34.8 mF·cm⁻¹. -2 This confirmed that it has the largest ECSA, indicating that CoMoO4@CoZn-P / NF can provide more electrochemically active sites under alkaline HER conditions.
[0051] like Figure 11 As shown, the CoMoO4@CoZn-P / NF catalyst exhibits good HER catalytic performance in 30℃ and 1 M KOH solution. Further investigation was conducted into the stability of the catalyst's HER catalytic activity over a long period. Figure 7 As shown in Figure a, the HER stability of the CoMoO4@CoZn-P / NF catalyst was tested by the galvanostatic method at a current density of 100 mA·cm⁻¹. -2 At that time, the CoMoO4@CoZn-P / NF catalyst could maintain stable catalytic activity for up to 50 h. Figure 7 Figure b shows that the LSV curve after 5000 cycles is basically consistent with that after the first cycle, indicating that the catalyst has good stability. In summary, the CoMoO4@CoZn-P / NF catalyst prepared in this invention has good HER catalytic performance and high stability.
[0052] like Figure 12 As shown, the CoMoO4@CoZn-P / NF catalyst prepared by this simple method exhibits significant hydrogen evolution reaction performance. Its performance at 100 mA cm⁻¹ is [missing value]. -2 The overpotential at current density is as low as 111 mV, exhibiting exceptional performance. Its performance surpasses that of recently published non-precious metal catalysts, and this value is very close to the widely used benchmark in the literature—commercial Pt / C catalysts (typically around 86 mV), marking a significant breakthrough in the core activity indicators of non-precious metal catalysts.
[0053] Parametric performance descriptions of Examples 1 and 2. [hM1][zk2] Systematic electrochemical tests were conducted on CoMoO4@CoZn-P / NF catalysts obtained under different synthesis conditions, revealing significant differences in their performance. This highlights the crucial influence of the synthesis process on the catalyst's microstructure and final activity.
[0054] The catalyst prepared in Example 1 exhibited excellent hydrogen evolution activity. Its activity at 10, 50, and 100 mA cm⁻¹ was [missing value]. -2 The overpotentials at current densities are only 80, 199, and 259 mV, respectively, demonstrating low reaction driving force requirements and good high-current performance. The corresponding Tafel slope is 149.1 mV dec. -1This indicates that the hydrogen evolution reaction is kinetically controlled by the Volmer step (water molecule dissociation). Furthermore, the catalyst exhibits a high double-layer capacitance (Cdl) of 12.4 mF cm⁻¹. -2 This directly confirms that it has a large electrochemical active surface area, exposing abundant active sites. In contrast, the catalyst performance of Example 2 is somewhat insufficient. At the same current density (10, 50, and 100 mA cm⁻¹), it... -2 The overpotentials at these values were 175, 270, and 330 mV, respectively, significantly higher than in Example 1. Although its Tafel slope (117.4 mV dec) -1 The value is slightly lower, suggesting that the kinetics of the surface reaction steps may be slightly different, but its double-layer capacitance (0.3 mF cm⁻¹) is still relatively high. -2 Compared to Example 1, the value was more than an order of magnitude lower. This directly indicates that its actual electrochemical active area is severely insufficient and the number of active sites is scarce, which is the main reason for its poor overall catalytic performance.
[0055] In summary, the performance of the first two examples is far inferior to that of the catalyst in the subsequently optimized Example 3. The control of synthesis parameters can significantly affect the morphology of the catalyst and the degree of exposure of active sites. The success of Example 3 lies in its optimized conditions, which effectively increased the active surface area of the catalyst, thereby achieving a significant improvement in overall performance.
[0056] Therefore, this method not only provides a new high-performance, low-cost catalyst system, but also offers a clear example for designing practical electrode materials that can replace precious metals through multi-scale regulation strategies, which has important theoretical and application value.
Claims
1. A method for preparing a cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment, characterized in that, Including steps such as: Step S1: CoMoO4 / NF nanorods are synthesized on a nickel foam substrate via a hydrothermal reaction; Step S2: Introduce cobalt-molybdenum metal oxides by loading Co(OH)2 and Zn(OH)2 onto CoMoO4 / NF nanorods to form CoMoO4@CoZn-LDH / NF; Step S3: Synthesize the cobalt-based oxide phosphide heterojunction catalyst CoMoO4@CoZn-P / NF through phosphating reduction and ion exchange.
2. The method for preparing a cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to claim 1, characterized in that, In step S1, the nickel foam substrate is pretreated; The pretreatment includes the removal of surface oxides and oil stains from the nickel foam substrate, specifically including: immersing the nickel foam in 1-5 M HCl, water, and ethanol in sequence for ultrasonic cleaning, and then placing the pretreated nickel foam in anhydrous ethanol for later use.
3. The method for preparing a cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to claim 1, characterized in that, The synthesis of CoMoO4 / NF nanorods in step S1 specifically includes the following steps: S1.
1. Cobalt salt and molybdenum salt are added to water in sequence to form a mixed solution; S1.2 The stirred solution is clear and transparent; S1.3 Transfer the solution to the liner of the reactor and place the pretreated nickel foam inside. Then, place the sealed reactor into an electric heating oven for the reaction. S1.4 After the reaction is complete, the product is naturally cooled to room temperature, washed multiple times with ethanol and water, and dried in an electric heating oven to obtain CoMoO4 / NF nanorods.
4. The method for preparing a cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to claim 3, characterized in that, The cobalt salt is one or a mixture of two or more of cobalt nitrate, cobalt chloride, and cobalt acetate; the molybdenum salt is one or a mixture of two of ammonium molybdate and sodium molybdate; the mass ratio of the cobalt salt to the molybdenum salt is (270~310):(290~330).
5. The method for preparing a cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to claim 3, characterized in that, The reaction temperature described in S1.3 is 130 ℃~170 ℃, and the reaction time is 3~7 h; the drying temperature described in S1.4 is 40 ℃~80 ℃.
6. The method for preparing a cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to claim 1, characterized in that, The synthesis of CoMoO4@CoZn-LDH / NF in S2 includes the following steps: S2.1 Immerse CoMoO4 / NF nanorods in an aqueous solution containing cobalt salt, zinc salt, urea and ammonium fluoride; S2.2 Transfer to the Teflon liner of the high-pressure reactor, place the sealed reactor in an electric heating oven, and allow it to cool naturally to room temperature after the hydrothermal reaction. S2.
3. The CoMoO4@CoZn-LDH / NF was obtained by washing several times with ethanol and water and drying overnight in an electric heating oven.
7. The method for preparing a cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to claim 6, characterized in that, The zinc salt is one or more of zinc nitrate, zinc chloride, and zinc acetate; the mass ratio of the cobalt salt, zinc salt, urea, and ammonium fluoride is (270~310):(280~320):(220-260):(60-100).
8. The method for preparing a cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to claim 6, characterized in that, The reaction temperature described in S2.2 is 100 ℃~140 ℃, and the reaction time is 10~14 h; the drying temperature described in S2.3 is 40 ℃~80 ℃.
9. The method for preparing a cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to claim 1, characterized in that, The synthesis of CoMoO4@CoZn-P / NF in S3 includes the following steps: S3.1, CoMoO4@CoZn-LDH / NF is placed downstream of the tube furnace, and a ceramic boat containing sodium hypophosphite is placed downstream; S3.
2. Maintain the temperature at a fixed rate for a period of time, and remove the tube furnace after it has cooled to room temperature. S3.3 Washed several times with ethanol and water, and finally dried overnight in an electric heating oven. After natural cooling, a black CoMoO4@CoZn-P / NF catalyst was obtained.
10. The method for preparing a cobalt-based oxide phosphide heterojunction catalyst based on the hydrogen evolution reaction in an alkaline environment according to claim 9, characterized in that, In step S3.1, the amount of sodium hypophosphite added is 100-150 mg / cm³. 2 The foamed nickel substrate; the calcination temperature in S3.2 is 200 ℃~500 ℃, the heating rate is 1-5 ℃ / min, and the calcination time is 1~3h.