Three-phase heterogeneous structure catalyst and preparation method and application thereof

Abstract

The application discloses a three-phase heterogeneous structure catalyst, which comprises a first crystal phase, a second crystal phase and an amorphous phase, and the amorphous phase is located between the first crystal phase and the second crystal phase. The catalyst obtained by the application has the characteristics of high activity. The application also discloses a preparation method and application of the three-phase heterogeneous structure catalyst.

Description

[Technical Field]

[0001] This application relates to the field of water electrolysis technology, and in particular to the preparation method and application of three-phase heterostructure catalysts. [Background Technology]

[0002] Hydrogen energy, due to its high calorific value, good combustion performance, and clean, pollution-free nature, has the potential to replace traditional fossil fuels. Among current hydrogen production methods, water electrolysis is particularly noteworthy for its simplicity, wide availability of raw materials, and high product purity. However, the anodic oxygen evolution oxidation (OER) faces significant challenges (1.23V vs. RHE), prompting the search for alternative reactions with lower oxidation potentials to reduce the electricity consumption for H2 production. Due to the low theoretical oxidation potential of hydrazine hydrate (-0.33V vs. RHE), the hydrazine oxidation reaction (HzOR) has emerged as a promising alternative to OER. Therefore, hydrogen production assisted by hydrazine hydrate has attracted considerable attention. The key to this system lies in highly efficient catalysts, especially those with dual HER and HzOR functions. Noble metal-based materials have traditionally possessed excellent bifunctional properties, but their high cost and scarcity hinder their widespread application. Therefore, there is an urgent need to develop highly active, sustainable, and economically viable catalysts capable of simultaneously catalyzing HER and HzOR. [Summary of the Invention]

[0003] The purpose of this application is to provide a three-phase heterostructure catalyst and its preparation method.

[0004] A three-phase heterostructure catalyst is disclosed, comprising a first crystalline phase, a second crystalline phase, and an amorphous phase, wherein the amorphous phase is located between the first and second crystalline phases. If the first and second crystalline phases are in direct contact, lattice mismatch will occur, leading to instability of the heterostructure during the catalytic reaction, thereby reducing its activity and stability. However, an amorphous phase transition layer exists between the first and second crystalline phases. Because the amorphous phase has no fixed lattice constant, there is no lattice mismatch when it comes into contact with the crystalline phases. Therefore, it can buffer the lattice mismatch caused by the two crystalline phases, thereby enhancing the stability of the heterostructure.

[0005] Furthermore, the first crystalline phase is a transition metal-based compound, the second crystalline phase is a metal-based compound, and the amorphous phase is any one of a sulfide, a nitride, or a phosphide.

[0006] Furthermore, the transition metal-based compound is any one of cobalt-based phosphides, cobalt-based sulfides, cobalt-based nitrides, nickel-based phosphides, nickel-based sulfides, and nickel-based nitrides. The metal-based compound is any one of cerium-based oxides, cerium-based sulfides, molybdenum-based oxides, and molybdenum-based sulfides.

[0007] Furthermore, the first crystalline phase is Co(OH)F, the second crystalline phase is CeO2, and the amorphous phase is Co-S. The amorphous phase Co-S has abundant hybrid orbitals and a mild adsorption-desorption capacity for hydrogen. At the same time, S atoms can form ionic bonds with Co(OH)F and CeO2, thus exhibiting excellent interfacial bonding ability and enhancing the stability of the heterostructure.

[0008] A method for preparing a three-phase heterostructure catalyst includes the following steps:

[0009] Step 1: Mix the cobalt source, urea, ammonium fluoride, and solvent to obtain a mixture;

[0010] In step 1, the molar ratio of cobalt source: urea: ammonium fluoride is 1:4:5.

[0011] In step 1, the solvent is water, ethanol, methanol, or dimethylformamide.

[0012] In step 1, the cobalt source is at least one of cobalt nitrate, cobalt acetate, cobalt chloride, cobalt sulfate, and cobalt oxide.

[0013] In step 1, the ratio of the molar amount of cobalt in the cobalt source to the volume fraction of the solvent in step 1 is 1:(10-50), with the molar amount in mmol and the volume fraction in ml.

[0014] Step 2: The mixture without substrate is hydrothermally heated at 100-120℃ for 5-10 hours to obtain a sample. The sample is washed and dried to obtain a precursor, wherein the substrate material is nickel foam (NF).

[0015] In step 2, anhydrous ethanol and water are used alternately for washing.

[0016] In step 2, the drying temperature is room temperature to 100℃, and the drying time is 3 to 15 hours.

[0017] Step 3: Immerse the precursor obtained above in a solution containing sulfides, then place it in a reaction vessel and react at 120°C for 10 hours to obtain an intermediate.

[0018] In step 3, the sulfide is at least one of Na2S·9H2O, thiourea, H2S, and sulfur powder, and the molar ratio is precursor:sulfide = 2:1.

[0019] Step 4: Immerse the intermediate obtained in Step 3 in an ethanol solution containing cerium nitrate hexahydrate and hexamethylenetetramine and react at 140°C for 6 hours to obtain a three-phase heterostructure catalyst.

[0020] In step 4, the molar concentration ratio is cerium nitrate hexahydrate: hexamethylenetetramine = 1:3.

[0021] The three-phase heterostructure catalyst obtained above can be used in at least one of the following reactions: hydrogen evolution reaction (HER), hydrazine oxidation reaction (HzOR), anodic oxygen evolution reaction, and urea oxidation reaction.

[0022] The obtained three-phase heterostructure catalyst possesses abundant heterostructure interfaces and numerous dangling bonds, which enhances the adsorption of reactants. Furthermore, the three-dimensional hierarchical structure improves space utilization, thereby increasing the number of active reaction sites. Additionally, this nanoneedle-like three-dimensional hierarchical structure exhibits a tip effect, enhancing the local electric field strength and thus improving electron transfer efficiency, enabling the simultaneous catalysis of HzOR and HER. At 10 mA cm⁻¹ -2 Under these conditions, the potentials for HER and HzOR are only 158 mV and 80 mV, respectively. The coupled Co(OH)F / Co-S / CeO2 dual electrode configuration is set at 10 mA cm⁻¹. -2 Under certain conditions, hydrogen can be efficiently produced by the complete hydrolysis of hydrazine hydrate (OHzS) with only a battery voltage of 0.2V. [Attached Image Description]

[0023] Figure 1 This is the XRD pattern of the three-phase heterostructure catalyst obtained in this application;

[0024] Figure 2 This is a TEM image of the three-phase heterostructure catalyst obtained in this application;

[0025] Figure 3 This is an HRTEM image of the three-phase heterostructure catalyst obtained in this application;

[0026] Figure 4 The graphs show the linear sweep voltammetry (LSV) curves of Co(OH)F / Co-S / CeO2 / NF obtained in Example 1, Co(OH)F / Co-S / NF obtained in Comparative Example 1, and Co(OH)F / CeO2 / NF obtained in Comparative Example 2 in 1M KOH electrolyte.

[0027] Figure 5 These are Tafel diagrams of Co(OH)F / Co-S / CeO2 / NF obtained in Example 1, Co(OH)F / Co-S / NF obtained in Comparative Example 1, and Co(OH)F / CeO2 / NF obtained in Comparative Example 2 of this application;

[0028] Figure 6 These are EIS diagrams of Co(OH)F / Co-S / CeO2 / NF obtained in Example 1 of this application, Co(OH)F / Co-S / NF obtained in Comparative Example 1, and Co(OH)F / CeO2 / NF obtained in Comparative Example 2.

[0029] Figure 7This is an electrochemical active area (ECSA) diagram of Co(OH)F / Co-S / CeO2 / NF obtained in Example 1 of this application, Co(OH)F / Co-S / NF obtained in Comparative Example 1, and Co(OH)F / CeO2 / NF obtained in Comparative Example 2.

[0030] Figure 8 This is a comparison of the cathode LSV of the three-phase heterostructure catalyst obtained in this application before and after 1000 CV cycles;

[0031] Figure 9 This is a cathode stability test diagram of the three-phase heterostructure catalyst obtained in this application;

[0032] Figure 10 This is an anodic polarization curve of the three-phase heterostructure catalyst obtained in this application before and after the addition of 0.5M N2H4;

[0033] Figure 11 These are Tafel plots of Co(OH)F / Co-S / CeO2 / NF obtained in Example 1 of this application, Co(OH)F / Co-S / NF obtained in Comparative Example 1, and Co(OH)F / CeO2 / NF obtained in Comparative Example 2 in 1M KOH and 0.5M N2H4.

[0034] Figure 12 The images show the EIS plots of Co(OH)F / Co-S / CeO2 / NF obtained in Example 1, Co(OH)F / Co-S / NF obtained in Comparative Example 1, and Co(OH)F / CeO2 / NF obtained in Comparative Example 2 in 1M KOH and 0.5M N2H4.

[0035] Figure 13 This is a comparison of the anode LSV of the three-phase heterostructure catalyst obtained in this application before and after 1000 CV cycles;

[0036] Figure 14 The three-phase heterostructure catalyst obtained in this application exhibits performance at 10 mA cm⁻¹ -2 Anode stability test diagram;

[0037] Figure 15 This is a diagram showing the total water hydrolysis performance of Co(OH)F / Co-S / CeO2 / NF obtained in Example 1 of this application;

[0038] Figure 16 These are water adsorption free energy diagrams of Co(OH)F / Co-S / CeO2 / NF obtained in Example 1, Co(OH)F / Co-S / NF obtained in Comparative Example 1, and Co(OH)F / CeO2 / NF obtained in Comparative Example 2.

[0039] Figure 17These are ΔGH* graphs of Co(OH)F / Co-S / CeO2 / NF obtained in Example 1, Co(OH)F / Co-S / NF obtained in Comparative Example 1, and Co(OH)F / CeO2 / NF obtained in Comparative Example 2.

[0040] Figure 18 These are DOS diagrams of Co(OH)F / Co-S / CeO2 / NF obtained in Example 1, Co(OH)F / Co-S / NF obtained in Comparative Example 1, and Co(OH)F / CeO2 / NF obtained in Comparative Example 2.

Detailed Implementation Methods

[0041] The present application will be further described below with reference to the accompanying drawings and specific embodiments:

[0042] To enable those skilled in the art to better understand the technical solutions of this application, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the drawings described below are merely some embodiments of this application. Those skilled in the art can obtain other drawings based on these drawings without creative effort. The directional terms such as "up" and "down" used herein are defined by the relative positions of the components shown in the drawings, and are only used for clarity and convenience in expressing the technical solutions. It should be understood that the directional terms used herein should not limit the scope of protection claimed in this application.

[0043] The raw material information involved in the following examples is as follows:

[0044] name Chemical formula Specification Manufacturer Cobalt nitrate hexahydrate <![CDATA[Co(NO3)2·6H2O]]> AR (analytical purity) Shanghai McLean Biochemical Technology Co., Ltd. urea <![CDATA[CH4N2O]]> AR Shanghai McLean Biochemical Technology Co., Ltd. ammonium fluoride <![CDATA[NH4F]]> AR Shanghai McLean Biochemical Technology Co., Ltd. Cerium nitrate hexahydrate <![CDATA[Ce(NO3)2·6H2O]]> AR Shanghai McLean Biochemical Technology Co., Ltd. Sodium sulfide nonahydrate <![CDATA[Na2S·9H2O]]> AR Shanghai McLean Biochemical Technology Co., Ltd. potassium hydroxide KOH AR Shanghai McLean Biochemical Technology Co., Ltd. Hexamethylenetetramine <![CDATA[C6H 12 N4]]> AR Sinopharm Chemical Reagent Co., Ltd. hydrochloric acid HCl AR Sinopharm Chemical Reagent Co., Ltd. hydrazine hydrate <![CDATA[H4N2·H2O]]> AR Shanghai Lingfeng Chemical Reagent Co., Ltd. ethanol <![CDATA[CH3CH2OH]]> AR Hangzhou Gaojing Chemical Reagent Co., Ltd.

[0045] In the following embodiments, the substrate was obtained as follows: NF was cut into 1*2 square centimeter sheets, ultrasonically cleaned in hydrochloric acid, deionized water, and ethanol for 10 minutes each, and dried in a 60°C oven for 12 hours to obtain the substrate. The nickel foam had a strength of 90 PPI, dimensions of 200*300*1.5 mm, and was manufactured by Suzhou Kunshan Guangjiayuan Electronic Materials Business Department.

[0046] Example 1

[0047] Mix 2.4 mmol Co(NO3)2·6H2O, 9.6 mmol NH4F, 12 mmol urea CH4N2O and 30 ml water, stir well to obtain a mixture, immerse the mixture without substrate in 120℃ hydrothermal heating for 6 h to obtain sample Co(OH)F / NF, cool the sample to room temperature, wash with ethanol and water alternately 3 times, and dry in 60℃ oven for 4 h to obtain Co(OH)F / NF;

[0048] The Co(OH)F / NF obtained above was immersed in a solution containing 30 ml of 0.05 mol / L (0.05 M) sodium sulfide nonahydrate and then placed together in a reaction vessel. The reaction was carried out at 120 °C for 10 h to obtain Co(OH)F / Co-S / NF.

[0049] 0.3 mmol cerium nitrate hexahydrate, 0.9 mmol hexamethylenetetramine, 10 mL ethanol, and the Co(OH)F / Co-S / NF prepared above were placed in a high-pressure reactor and reacted at 140 °C for 6 h to obtain Co(OH)F / Co-S / CeO2 / NF.

[0050] Comparative Example 1

[0051] 2.4 mmol Co(NO3)2·6H2O, 9.6 mmol NH4F, 12 mmol urea (CON2H4) and 30 ml water were mixed and stirred until homogeneous to obtain a mixture. The mixture without substrate was immersed in the mixture and heated hydrothermally at 120℃ for 6 h to obtain a sample. The sample was cooled to room temperature, washed three times alternately with ethanol and water, and dried in an oven at 60℃ for 4 h to obtain Co(OH)F / NF.

[0052] The Co(OH)F / NF obtained above was immersed in a solution containing 30 ml (0.05 M) sodium sulfide and then placed together in a reaction vessel. The reaction was carried out at 120 °C for 10 h to obtain Co(OH)F / Co-S / NF.

[0053] Comparative Example 2

[0054] 2.4 mmol Co(NO3)2·6H2O, 9.6 mmol NH4F, 12 mmol urea (CON2H4) and 30 ml water were mixed and stirred until homogeneous to obtain a mixture. The mixture without substrate was immersed in the mixture and heated hydrothermally at 120℃ for 6 h to obtain a sample. The sample was cooled to room temperature, washed three times alternately with ethanol and water, and dried in an oven at 60℃ for 4 h to obtain Co(OH)F / NF.

[0055] The Co(OH)F / NF obtained above was immersed in a solution containing 0.3 mmol cerium nitrate hexahydrate, 0.9 mmol hexamethylenetetramine, and 10 mL ethanol, and then placed together in a reaction vessel and reacted at 140 °C for 6 h to obtain Co(OH)F / CeO2 / NF.

[0056] To verify the successful synthesis of the bifunctional catalyst with multiple heterogeneous interfaces of the present invention, its structure was characterized.

[0057] The phase composition of the samples was characterized by X-ray powder diffraction (XRD, Bruker D8 Discover Cu target). The morphology and lattice information of the samples were analyzed by transmission electron microscopy (TEM, JEM-2100). The HER and HzOR performance of the catalyst in a solution containing 0.5 M hydrazine hydrate and 1.0 M potassium hydroxide was tested using an electrochemical workstation (CHI760E). Linear sweep voltammetry (LSV) was performed at a rate of 5 mV·s. -1 All potentials are corrected using the following formula:

[0058] ERHE=EHg / HgO+0.098+0.0591×pH-IR

[0059] Overpotential was further compensated by incorporating I (current in LSV) and solution internal resistance (R). Electrochemical impedance spectroscopy (EIS) measurements were performed at 1.326 V vs. RHE at frequencies ranging from 100,000 to 0.1 Hz. Double-layer capacitance (Cd) l The current density (CV) curves are derived from the cyclic voltammograms (CV) between 0.986V vs. RHE and 1.126V vs. RHE. The current density difference at the intermediate potential is plotted against the scan rate, and half of the linear slope is taken as Cd. l value.

[0060] Figure 1 The X-ray diffraction (XRD) patterns of Co(OH)F / Co-S / CeO2 / NF and Co(OH)F / Co-S / NF obtained in Embodiment 1 and Comparative Example 1 of this invention are shown. Figure 1 In the diagram, the horizontal axis represents the X-ray diffraction angle, and the vertical axis represents the X-ray diffraction intensity. For example... Figure 1 As shown, in addition to the diffraction peaks of nickel foam, some diffraction peaks appeared at 20.83°, 32.31°, 33.53°, 35.56°, 38.78°, and 39.91°, corresponding to the (110), (310), (201), (111), (211), and (410) crystal planes of Co(OH)F, respectively (Joint Committee on Powder Diffraction Standards (JCPDS) No. 50-0827). Furthermore, after hydrothermal treatment with sodium sulfide solution, the product exhibited the same peak values ​​as Co(OH)F / NF, indicating that the sulfide products on the Co(OH)F surface are in an amorphous state. After CeO2 was deposited on the surface of Co(OH) / Co-S nanoneedles, it retained the Co(OH)F diffraction peaks and showed peaks at 28.54°, 47.48°, and 56.34° corresponding to the (111), (220), and (311) crystal planes of CeO2 (JCPDS No. 75-0120). This confirms the successful preparation of the Co(OH)F / Co-S / CeO2 three-phase heterostructure.

[0061] Figures 2 to 3 These are transmission electron microscopy (TEM) images of Co(OH)F / Co-S / CeO2 / NF obtained in Embodiment 1 of this invention. Figure 2 It can be seen that Co(OH)F / Co-S / CeO2 exhibits a nanoneedle-like structure with a diameter of approximately 80 nanometers. This three-dimensional hierarchical structure of nanoneedles exhibits a tip effect, enhancing the local electric field strength and thus improving electron transfer efficiency. Furthermore, from... Figure 3 It can be seen that there are obvious crystalline and amorphous regions. The amorphous phase Co-S is located between the crystalline phase Co(OH)F and the crystalline phase CeO2. The amorphous phase Co-S has abundant hybrid orbitals and has a mild adsorption-desorption capacity for hydrogen. At the same time, S atoms can form bonds with Co(OH)F and CeO2 through ionic bonding, thus having excellent interfacial bonding ability and improving the stability of the heterostructure.

[0062] from Figure 4 It can be seen that Comparative Example 1, using amorphous Co-S, has an overpotential of 186 mV, while the overpotential of the comparative example with the introduction of crystalline CeO2 is 150 mV. Example 1, by simultaneously introducing both amorphous Co-S and crystalline CeO2, has an overpotential of 158 mV. This indicates that the addition of multiple interfaces has a positive impact on improving HER performance. Furthermore, at 100 mA cm⁻¹... -2 Under these conditions, the overpotential of Co(OH)F / Co-S / CeO2 / NF is also lower than that of Co(OH)F / Co-S / NF and Co(OH)F / CeO2 / NF, at only 276mV.

[0063] from Figure 5 It can be seen that the Tafel slope of Co(OH)F / Co-S / CeO2 / NF obtained in Example 1 is 109.11 mV dec. -1 This is lower than the 114.20 mV dec of the two-phase heterojunction Co(OH)F / Co-S / NF obtained in Comparative Example 1. -1 It is also lower than the 130.88 mV dec of the two-phase heterojunction Co(OH)F / CeO2 / NF. -1 This indicates that the reaction kinetics of the three-phase Co(OH)F / Co-S / CeO2 heterojunction are higher than those of other similar heterojunctions, and the introduction of the hetero interface is beneficial to improving the HER kinetics.

[0064] Furthermore, to gain a deeper understanding of its catalytic ability, electrochemical impedance spectroscopy (EIS) studies were also conducted. For example... Figure 6 As shown, charge transfer resistance (R) ct)The sequence is as follows: Co(OH)F / Co-S / CeO2 / NF (2.16Ω) < Co(OH)F / Co-S / NF (2.63Ω) < Co(OH)F / CeO2 / NF (2.84Ω). This indicates that Co(OH)F / Co-S / CeO2 / NF has a higher electron transfer ability than other similar materials. In addition, we also detected the double-layer capacitance (C dl ), which proves that the example has the largest electrochemically active area. As can be seen from Figure 7 , the C dl value of Co(OH)F / Co-S / CeO2 / NF is 83.12 mF cm -2 , exceeding 77.95 mF cm -2 of the biphasic heterojunction Co(OH)F / Co-S / NF and 3.33 mF cm -2 of Co(OH)F / CeO2 / NF, thus highlighting the abundance of its active sites. In addition, we also carried out a stability test on Co(OH)F / Co-S / CeO2 / NF. As shown in Figure 8 , after 1000 CV cycles, the LSV curves almost coincide, indicating its good stability. At the same time, as shown in Figure 9 , Co(OH)F / Co-S / CeO2 / NF can also maintain a stable potential at 10 mA cm -2 for 48 hours, further indicating its excellent stability. After the stability test, Co(OH)F / Co-S / CeO2 / NF maintained a similar microscopic morphology and phase structure as before, indicating its good structural durability.

[0065] As shown in Figure 10 , the HzOR of Co(OH)F / Co-S / CeO2 / NF is better than OER, which indicates that the anodic oxidation ability is significantly enhanced after introducing hydrazine hydrate into the electrolyte.

[0066] In addition, as shown in Figure 11 , the Tafel slope value of Co(OH)F / Co-S / CeO2 / NF is lower, being 50.16 mV dec -1 . It is lower than 109.75 mV dec -1 of the biphasic heterostructure Co(OH)F / Co-S / NF and 141.33 mV dec -1 of Co(OH)F / CeO2 / NF. This indicates that introducing a triphasic heterostructure into Co(OH)F can promote the reaction kinetics more than a biphasic heterostructure. In addition, as shown in Figure 12As shown, Co(OH)F / Co-S / CeO2 / NF exhibits a lower charge transfer resistance (1.74 Ω), significantly lower than the 8.87 Ω of Co(OH)F / Co-S / NF and the 208.4 Ω of Co(OH)F / CeO2 / NF. This confirms the beneficial effect of the three-phase heterostructure on electrocatalytic activity. Furthermore, from... Figure 13 The LSV curves shown are the result of 1000 CV cycles and the curves from... Figure 14 The 10mA cm shown -2 The Co(OH)F / Co-S / CeO2 / NF exhibited excellent stability after maintaining a stable potential for 48 hours.

[0067] Given the significant bifunctional catalytic activity of Co(OH)F / Co-S / CeO2 / NF, Co(OH)F / Co-S / CeO2 / NF was used as both the cathode and anode. Figure 15 As shown, compared with total water splitting (OWS), total hydrazine hydrolysis (OHzS) has superior thermodynamic and kinetic advantages, requiring only 0.2...

[0068] V can reach 10mA cm -2 It has 1.4V less than the traditional OWS system.

[0069] like Figure 16 As shown, Co(OH)F / Co-S / CeO2 exhibits a moderate water adsorption free energy (0.12 eV) higher than that of Co(OH)F / Co-S (-1.55 eV), which is favorable for subsequent reactions. Notably, its water dissociation energy (0.11 eV) is lower than that of Co(OH)F / Co-S (2.21 eV), indicating superior performance in alkaline solutions. The hydrogen adsorption-desorption free energy difference (ΔG) is also shown. H* () is a key indicator for measuring hydrogen evolution performance, such as Figure 17 As shown, the value of Co(OH)F / Co-S / CeO2 (-0.28 eV) is more balanced than that of Co(OH)F / Co-S (-0.66 eV). These results indicate that the strongly coupled three-phase heterostructure promotes water dissociation and balanced hydrogen adsorption / desorption behavior, thereby giving Co(OH)F / Co-S / CeO2 / NF superior HER performance.

[0070] In addition, the density of states (DOS) of Co(OH)F / Co-S / CeO2 and Co(OH)F / Co-S were calculated, such as Figure 18 As shown, the density of states at the Fermi level of the Co(OH)F / Co-S / CeO2 three-phase heterojunction exceeds that of the Co(OH)F / Co-S, which means that more charge carriers will participate in the catalytic processes of surface HER and HzOR, thereby significantly improving its electrocatalytic activity.

[0071] It should be noted that the above embodiments are only used to illustrate this application and are not intended to limit the technical solutions described in this application. Although this specification has described this application in detail with reference to the above embodiments, those skilled in the art should understand that they can still make modifications or equivalent substitutions to this application. All technical solutions and improvements that do not depart from the spirit and scope of this application should be covered within the scope of the claims of this application.

Claims

1. A three-phase heterostructured catalyst, characterized in that, The catalyst comprises a first crystal phase, a second crystal phase and an amorphous phase, the amorphous phase is located between the first crystal phase and the second crystal phase, the first crystal phase is Co(OH)F, the second crystal phase is CeO2, and the amorphous phase is Co-S.

2. A preparation method of a three-phase heterostructure catalyst, the preparation method comprising the following steps: Step 1: mixing a cobalt source, urea, ammonium fluoride and a solvent to obtain a mixed solution, and the molar ratio of the cobalt source, urea and ammonium fluoride is 1:4:5; Step 2: hydrothermally treating the mixed solution without a substrate at 100-120 DEG C for 5-10 hours to obtain a sample, washing and drying the sample to obtain a precursor, wherein the material of the substrate is foamed nickel; Step 3: immersing the precursor obtained in the above step into a solution containing sulfide, and then placing it into a reaction kettle to react at 120 DEG C for 10 hours to obtain an intermediate; Step 4: immersing the intermediate obtained in step 3 into an ethanol solution containing cerium nitrate hexahydrate and hexamethylenetetramine, and reacting at 140 DEG C for 6 hours.

3. The method of claim 2, wherein the three-phase heterostructure catalyst is prepared by the steps of: The solvent in step 1 is water, ethanol, methanol or dimethylformamide; and the cobalt source is at least one of cobalt nitrate, cobalt acetate, cobalt chloride, cobalt sulfate and cobalt oxide.

4. The method of claim 2, wherein the three-phase heterostructure catalyst is prepared by the steps of: The ratio of the number of moles of cobalt in the cobalt source to the volume of the solvent is 1: (10-50), and the unit of the number of moles is mmol, and the unit of the volume is ml.

5. The method of claim 2, wherein the three-phase heterostructure catalyst is prepared by the steps of: The molar concentration ratio of cerium nitrate hexahydrate to hexamethylenetetramine is 1:

3.

6. The method of claim 2, wherein the three-phase heterostructure catalyst is prepared by the steps of: In step 2, anhydrous ethanol and water are used alternately for washing, and the drying temperature is room temperature-100 DEG C, and the drying time is 3-15 hours.

7. The method of claim 2, wherein the three-phase heterostructure catalyst is prepared by the steps of: The sulfide is at least one of Na2S·9H2O, thiourea, H2S and sulfur powder, and the molar ratio of the precursor to the sulfide is 2:

1.

8. An application, characterized in that The three-phase heterostructure catalyst of claim 1 or the three-phase heterostructure catalyst prepared by any one of claims 2-7 is applied to an electrocatalytic reaction, and the electrocatalytic reaction is at least one of cathodic hydrogen evolution reaction, hydrazine oxidation reaction, anodic oxygen evolution reaction and urea oxidation reaction.

Images