An oxygen-linked single-atom oxide transition metal catalyst, its preparation method and application

Abstract

This invention relates to a method for preparing an oxygen-linked single-atom-oxide transition metal catalyst, comprising the following steps: adding a molybdenum source to a graphene oxide solution, followed by adding a zirconium source and stirring to obtain a precursor solution; subjecting the precursor solution to a hydrothermal reaction to obtain a reaction product; drying the reaction product, and then performing high-temperature nitridation using chemical vapor deposition to obtain an oxygen-linked single-atom-oxide transition metal catalyst. This invention utilizes ammonium molybdate tetrahydrate and zirconium tetrachloride as metal precursors, ammonia as a nitrogen source, and synthesizes an oxygen-linked single-atom-oxide transition metal catalyst using hydrothermal reaction and chemical vapor deposition. The catalyst prepared by this invention exhibits extremely excellent electrocatalytic water electrolysis efficiency in both pure water and seawater environments, possessing significantly high catalytic activity, achievable high current density, extremely low Tafel slope, and high stability.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalysis technology, and specifically relates to an oxygen-linked single-atom oxide transition metal catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen production driven by renewable energy power generation is an effective solution to alleviate the energy pressure currently caused by the large-scale use of fossil fuels. Hydrogen, as a new type of energy, possesses sustainable development characteristics, has a high calorific value, enormous application potential, and can achieve zero carbon emissions. Among various hydrogen production technologies, water electrolysis is expected to become the main technology in the future because it can fully utilize renewable and clean energy sources such as wind and solar power. The hydrogen evolution reaction (HER), as a half-reaction of water electrolysis, requires a catalyst to accelerate its slow kinetics.

[0003] Single-atom catalysts (SACs) possess superior atom utilization efficiency, customizable electronic states, and excellent reaction selectivity, thus significantly enhancing catalytic performance. Molybdenum (Mo), a transition metal element in the 4d block, exhibits variable oxidation states and coordination numbers. Mo SACs have shown great promise in electrocatalysis, particularly in the development of electrocatalysts for electrocatalysis in HER (thermal reactions). However, the increased surface energy of single atoms and the lack of favorable attachment sites often ultimately lead to the aggregation of metal atoms into nanoparticles or clusters. Recently, the chemical bonding of isolated metal SACs with the compatible surfaces of highly interacting metal oxides has proven helpful in constructing and preserving SACs in various chemical processes. The strong covalent interactions between single atoms and this matrix effectively anchor individual atoms, preventing the formation of aggregated particles. ZrO2 exhibits excellent chemical stability and corrosion resistance in both acidic and alkaline electrolytes, ensuring long-term durability and operational stability in HER. However, the HER performance of ZrO2 is constrained by poor charge transfer and low active site density, limiting electron transfer efficiency. In particular, metal oxides are more efficient at cleaving HO-H bonds, but perform poorly in other important hydrogen adsorption and desorption processes. Controlling oxygen vacancies (V... O Modifying the electronic structure, active sites, and surface characteristics of oxygen-containing electrocatalysts can significantly improve their efficiency. Therefore, selecting a simple and effective strategy to prepare a single-atom oxide material rich in oxygen vacancy defects for application in HER is very promising. Summary of the Invention

[0004] The purpose of this invention is to provide an oxygen-linked single-atom oxide transition metal catalyst, its preparation method and application, which has high electrocatalytic activity for HER, excellent catalytic hydrogen evolution reaction performance and good stability in acidic and alkaline pure water and seawater, and also exhibits good performance and stability in alkaline anion exchange membrane (AEM) electrolyzers.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An oxygen-linked single-atom oxide transition metal catalyst, its preparation method, and its application, comprising the following steps:

[0007] S1. Add a molybdenum source to the graphene oxide solution, then add a zirconium source. Mix the graphene with the metal solution and sonicate for 20-30 minutes to obtain a precursor solution. Perform a hydrothermal reaction on the precursor solution to obtain the reaction product.

[0008] S2. The reaction product was dried and then subjected to high-temperature nitriding using chemical vapor deposition to obtain an oxygen-linked single-atom oxide transition metal catalyst.

[0009] Preferably, the percentage of molybdenum in the molybdenum source relative to the mass of graphene oxide is 5-15%; and the percentage of zirconium in the zirconium source relative to the mass of graphene oxide is 3-7%.

[0010] Preferably, the molybdenum source is ammonium molybdate tetrahydrate; and the zirconium source is zirconium tetrachloride.

[0011] Preferably, in step S1, the concentration of the graphene oxide solution is 1-3 mg / mL.

[0012] Preferably, in step S1, the temperature of the hydrothermal reaction is 160–220°C, and the time of the hydrothermal reaction is 8–24 hours.

[0013] Preferably, in step S2, the drying process is freeze drying, and the freeze drying time is 6 to 12 hours.

[0014] Preferably, in step S2, the high-temperature nitriding using chemical vapor deposition includes the following steps: nitriding is carried out in a mixed atmosphere of argon and ammonia, with a reaction temperature of 600–1000°C, a reaction time of 1–3 h, an argon flow rate of 100 ± 10 sccm, and an ammonia flow rate of 50 ± 10 sccm.

[0015] In another aspect, the present invention provides an oxygen-linked single-atom oxide transition metal catalyst, which is prepared by the preparation method described above.

[0016] In another aspect, the present invention provides the application of the oxygen-linked single-atom oxide transition metal catalyst described above as a catalyst for the electrocatalytic hydrogen evolution reaction.

[0017] In another aspect, the present invention provides the application of the oxygen-linked single-atom oxide transition metal catalyst described above as a cathode catalyst for anion exchange membranes.

[0018] This invention utilizes (NH4)6Mo7O 24 Using 4H₂O and ZrCl₄ as metal precursors and ammonia (NH₃) as the nitrogen source, an oxygen-linked single-atom oxide transition metal catalyst was synthesized via hydrothermal reaction and chemical vapor deposition. During the chemical vapor deposition process, ZrO₄... 2-x Clusters form numerous oxygen vacancies under high temperature and pressure, which connect to Mo single atoms via oxygen bridges. These vacancies are then anchored to the single atoms through defects, exposing more active sites. This is because the Mo single atoms and ZrO... 2-x The strong metal-support interaction between the substrates and the excellent durability of the single-atom oxide transition metal catalyst further promote hydrogen production and stability.

[0019] The catalyst prepared by this invention possesses abundant functional groups, including hydroxyl (-OH) functional groups, which can adsorb water molecules through hydrogen bonding and other interactions, making it easier for water molecules to accumulate on the catalyst surface, thereby increasing the reactant concentration and accelerating the reaction rate. Conjugated carbon-carbon double bonds (C=C) can construct an electron delocalization system within the material. In the hydrogen evolution reaction, good conductivity ensures rapid electron transport from the electrode to the active site of the catalyst, promoting the proton reduction reaction (2H+). + +2e - →H2), thereby improving the kinetic performance of the hydrogen evolution reaction.

[0020] The catalyst prepared by this invention has electrocatalytic hydrogen evolution performance and has the advantages of high activity, low initial potential, high current density, small Tafel slope, and stable performance. When used as an anion exchange membrane battery catalyst, it exhibits excellent power density and stability and has a very broad application prospect. Attached Figure Description

[0021] Figure 1 The Mo-ZrO prepared in Example 1 2-x XRD pattern of / NG composite material;

[0022] Figure 2 The Mo-ZrO prepared in Example 1 2-x Raman spectrum of / NG composite material;

[0023] Figure 3 The Mo-ZrO prepared in Example 12-x Infrared spectrum of / NG composite material;

[0024] Figure 4 The Mo-ZrO prepared in Example 1 2-x TEM image of / NG composite material, where: a-500nm, b-100nm;

[0025] Figure 5 The Mo-ZrO prepared in Example 1 2-x HAADF-STEM image of / NG composite material.

[0026] Figure 6 The Mo-ZrO prepared in Example 1 2-x XPS full spectrum of / NG composite material, with inset showing elemental content;

[0027] Figure 7 The Mo-ZrO prepared in Example 1 2-x XPS plot of / NG composite material, where: a-Mo 3d, b-Zr 3d, cN 1s, dO 1s;

[0028] Figure 8 The Mo-ZrO prepared in Example 1 2-x The performance test graphs of / NG composite material as catalyst in electrochemical hydrogen evolution reaction are shown in Figure 8a, which is the polarization curve in 0.5M H2SO4 electrolyte, Figure 8c is the polarization curve in 1.0M KOH electrolyte, Figure 8b is the taphenanthrene curve in 0.5M H2SO4 electrolyte, and Figure 8d is the taphenanthrene curve in 1.0M KOH electrolyte. The scan rate is 50mV / s.

[0029] Figure 9 In Figure 'a', Mo-ZrO prepared in Example 1 is used. 2-x The cyclic curve of the long-term stability test of the / NG composite material in hydrogen-saturated 0.5M H2SO4 and 1.0M KOH solutions under constant current is shown in Figure b, where b is the Mo-ZrO prepared in Example 1. 2-x Cyclic curves of the / NG composite material in hydrogen-saturated 0.5M H2SO4 solution and 1.0M KOH solution.

[0030] Figure 10 Mo-ZrO prepared in Example 1 2-xThe performance test graphs of the / NG composite material in the electrochemical hydrogen evolution reaction in seawater are shown in Figure 1. a is the polarization curve in 0.5M H2SO4 seawater electrolyte, c is the polarization curve in 1.0M KOH seawater electrolyte, b is the taphenanthrene curve in 0.5M H2SO4 seawater electrolyte, and d is the taphenanthrene curve in 1.0M KOH seawater electrolyte. The scan rate is 50mV / s.

[0031] Figure 11 Mo-ZrO prepared in Example 1 2-x Polarization curves of the / NG composite material in an anion exchange membrane electrolyzer, tested under 1.0M KOH electrolyte conditions;

[0032] Figure 12 The Mo-ZrO prepared in Example 1 2-x Comparison of chronoamperometry curves of / NG composite materials in an anion exchange membrane electrolyzer, with test conditions of 1.0M KOH electrolyte and a constant current of 0.3A cm⁻¹. -2 The stability curve was obtained after 60 hours. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0034] The graphene oxide in the following examples was prepared by a modified Hummers method, the specific process of which is as follows: 3g of graphite powder and a concentrated H2SO4 and H3PO4 mixed solution (volume ratio 9:1) were added to a three-necked flask. 18g of KMnO4 solid was slowly added at a rotation speed of 200-350 rpm. The water bath temperature was set to 60℃, the stirring speed to 200-350 rpm, and the stirring time to 12h. After the reaction, the solution temperature was lowered to room temperature, and then poured into 400mL of pre-frozen deionized water and stirred evenly. H2O2 was slowly added to the solution in small amounts several times until the solution changed from purple to bright yellow. The solution was washed repeatedly with 30% HCl solution, deionized water, anhydrous ethanol, and diethyl ether in sequence. After vacuum drying at room temperature for 48h, pale yellow graphene oxide solid was obtained.

[0035] Example 1

[0036] A method for preparing a single-atom oxide transition metal catalyst with oxygen linkage includes the following steps:

[0037] Add 1.6g of graphene oxide solid to 80ml of deionized water, sonicate for 6 hours, and then sequentially add (NH4)6Mo7O 24A 4H₂O solution and a ZrCl₄ solution were placed in a graphene oxide solution, with Mo and Zr accounting for 15% and 7% of the graphene oxide mass, respectively. The mixture was sonicated for 30 min, then transferred to a hydrothermal reactor and heated to 180 °C for 12 h. After the reaction was complete, the hydrothermal reactor was cooled, and the hydrothermal product was freeze-dried for 6 h. The resulting product was then placed in a CVD furnace for high-temperature nitridation using chemical vapor deposition in a mixed atmosphere of Ar and NH₃. The reaction parameters were set as follows: temperature: 800 °C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, nitridation time: 3 h. This yielded an oxygen-linked single-atom oxide transition metal catalyst (Mo-ZrO₂). 2-x / NG).

[0038] Example 2

[0039] A method for preparing a single-atom oxide transition metal catalyst with oxygen linkage includes the following steps:

[0040] Add 1.6g of graphene oxide solid to 80ml of deionized water, sonicate for 6 hours, and then sequentially (NH4)6Mo7O 24 A 4H₂O solution and a ZrCl₄ solution were placed in a graphene oxide solution, with Mo and Zr accounting for 10% and 5% of the graphene oxide mass, respectively. The mixture was sonicated for 30 min, then transferred to a hydrothermal reactor and heated to 180 °C for 12 h. After the reaction, the reactor was cooled, and the hydrothermal product was freeze-dried for 6 h. The resulting product was then placed in a CVD furnace for high-temperature nitridation using chemical vapor deposition in a mixed atmosphere of Ar and NH₃. The reaction parameters were set as follows: temperature: 800 °C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, nitridation time: 3 h. This yielded an oxygen-linked single-atom oxide transition metal catalyst (Mo-ZrO₂). 2-x / NG@5)

[0041] Example 3

[0042] A method for preparing an oxygen-linked single-atom oxide transition metal catalyst includes the following steps:

[0043] Add 1.6g of graphene oxide solid to 80ml of deionized water, sonicate for 6 hours, and then sequentially add (NH4)6Mo7O 24Mo and ZrCl4 solutions were placed in a graphene oxide solution, with Mo and Zr accounting for 15% and 3% of the graphene oxide mass, respectively. The mixture was sonicated for 30 min, then transferred to a hydrothermal reactor and heated to 180 °C for 12 h. After the reaction, the reactor was cooled, and the hydrothermal product was freeze-dried for 6 h. The resulting product was then placed in a CVD furnace for high-temperature nitridation using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 800 °C, gas flow rates: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 3 h. This yielded an oxygen-linked single-atom oxide transition metal catalyst (Mo-ZrO). 2-x / NG@3).

[0044] Example 4

[0045] A method for preparing an oxygen-linked single-atom oxide transition metal catalyst includes the following steps:

[0046] Add 1.6g of graphene oxide solid to 80ml of deionized water, sonicate for 6 hours, and then sequentially add (NH4)6Mo7O 24 Mo and ZrCl4 solutions were placed in a graphene oxide solution, with Mo and Zr accounting for 5% and 7% of the graphene oxide mass, respectively. The mixture was sonicated for 30 min, then transferred to a hydrothermal reactor and heated to 180 °C for 12 h. After the reaction, the reactor was cooled, and the hydrothermal product was freeze-dried for 6 h. The resulting product was then placed in a CVD furnace for high-temperature nitridation using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 800 °C, gas flow rates: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 3 h. This yielded an oxygen-linked single-atom oxide transition metal catalyst (Mo-ZrO2). 2-x / NG).

[0047] Example 5

[0048] A method for preparing an oxygen-linked single-atom oxide transition metal catalyst includes the following steps:

[0049] Add 1.6g of graphene oxide solid to 80ml of deionized water, sonicate for 6 hours, and then sequentially add (NH4)6Mo7O 24Mo and ZrCl4 solutions were placed in a graphene oxide solution, with Mo and Zr accounting for 5% and 5% of the graphene oxide mass, respectively. The mixture was sonicated for 30 min, then transferred to a hydrothermal reactor and heated to 180 °C for 12 h. After the reaction, the reactor was cooled, and the hydrothermal product was freeze-dried for 6 h. The resulting product was then placed in a CVD furnace and subjected to high-temperature nitridation using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 800 °C, gas flow rate: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 3 h. This yielded an oxygen-linked single-atom oxide transition metal catalyst (Mo-ZrO2). 2-x / NG@5).

[0050] Example 6

[0051] A method for preparing an oxygen-linked single-atom oxide transition metal catalyst includes the following steps:

[0052] Add 1.6g of graphene oxide solid to 80ml of deionized water, sonicate for 6 hours, and then sequentially add (NH4)6Mo7O 24 A 4H₂O solution and a ZrCl₄ solution were placed in a graphene oxide solution, with Mo and Zr accounting for 5% and 3% of the graphene oxide mass, respectively. The mixture was sonicated for 30 min, then transferred to a hydrothermal reactor and heated to 180 °C for 12 h. After the reaction was complete, the hydrothermal reactor was cooled, and the hydrothermal product was freeze-dried for 6 h. The resulting product was then placed in a CVD furnace for high-temperature nitridation using chemical vapor deposition in a mixed atmosphere of Ar and NH₃. The reaction parameters were set as follows: temperature: 800 °C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, nitridation time: 3 h. This yielded an oxygen-linked single-atom oxide transition metal catalyst (Mo-ZrO₂). 2-x / NG@3).

[0053] Example 7

[0054] A method for preparing an oxygen-linked single-atom oxide transition metal catalyst includes the following steps:

[0055] Add 1.6g of graphene oxide solid to 80ml of deionized water, sonicate for 6 hours, and then sequentially add (NH4)6Mo7O 24Mo and ZrCl4 solutions were placed in a graphene oxide solution, with Mo and Zr accounting for 15% and 7% of the graphene oxide mass, respectively. The mixture was sonicated for 30 min, then transferred to a hydrothermal reactor and heated to 180 °C for 12 h. After the reaction, the reactor was cooled, and the hydrothermal product was freeze-dried for 6 h. The resulting product was then placed in a CVD furnace for high-temperature nitridation using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 600 °C, gas flow rates: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 3 h. This yielded an oxygen-linked single-atom oxide transition metal catalyst (Mo-ZrO2). 2-x / NG-600).

[0056] Example 8

[0057] A method for preparing a single-atom oxide transition metal catalyst having an oxygen bond includes the following steps:

[0058] Add 1.6g of graphene oxide solid to 80ml of deionized water, sonicate for 6 hours, and then sequentially add (NH4)6Mo7O 24 Mo and ZrCl4 solutions were placed in a graphene oxide solution, with Mo and Zr accounting for 15% and 7% of the graphene oxide mass, respectively. The mixture was sonicated for 30 min, then transferred to a hydrothermal reactor and heated to 180 °C for 12 h. After the reaction, the reactor was cooled, and the hydrothermal product was freeze-dried for 6 h. The resulting product was then placed in a CVD furnace for high-temperature nitridation using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 1000 °C, gas flow rate: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 3 h. This yielded an oxygen-linked single-atom oxide transition metal catalyst (Mo-ZrO2). 2-x / NG-1000).

[0059] Example 9

[0060] A method for preparing a single-atom oxide transition metal catalyst having an oxygen bond includes the following steps:

[0061] Add 1.6g of graphene oxide solid to 80ml of deionized water, sonicate for 6 hours, and then sequentially add (NH4)6Mo7O 24Mo and ZrCl4 solutions were placed in a graphene oxide solution, with Mo and Zr accounting for 15% and 7% of the graphene oxide mass, respectively. The mixture was sonicated for 30 min, then transferred to a hydrothermal reactor and heated to 180 °C for 12 h. After the reaction, the reactor was cooled, and the hydrothermal product was freeze-dried for 6 h. The resulting product was then placed in a CVD furnace for high-temperature nitridation using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 800 °C, gas flow rates: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 1 h. This yielded an oxygen-linked single-atom oxide transition metal catalyst (Mo-ZrO2). 2-x / NG-1h).

[0062] Example 10

[0063] A method for preparing a single-atom oxide transition metal catalyst having an oxygen bond includes the following steps:

[0064] Add 1.6g of graphene oxide solid to 80ml of deionized water, sonicate for 6 hours, and then sequentially add (NH4)6Mo7O 24 A 4H₂O solution and a ZrCl₄ solution were placed in a graphene oxide solution, with Mo and Zr accounting for 15% and 7% of the graphene oxide mass, respectively. The mixture was sonicated for 30 min, then transferred to a hydrothermal reactor and heated to 180 °C for 12 h. After the reaction was complete, the hydrothermal reactor was cooled, and the hydrothermal product was freeze-dried for 6 h. The resulting product was then placed in a CVD furnace for high-temperature nitridation using chemical vapor deposition in a mixed atmosphere of Ar and NH₃. The reaction parameters were set as follows: temperature: 800 °C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, nitridation time: 2 h. This yielded an oxygen-linked single-atom oxide transition metal catalyst (Mo-ZrO₂). 2-x / NG-2h).

[0065] The catalyst performance of Example 1 is evaluated and characterized as follows:

[0066] Electrochemical measurements were performed using a three-electrode system on an electrochemical workstation (CHI 660E). The oxygen-linked single-atom oxide transition metal catalyst obtained in Example 1 was dispersed in 1 mL of water / ethanol (v / v 4:1), followed by the addition of 40 μL of 5 wt% Nafio solution. The mixture was then sonicated to form a homogeneous suspension. 2.5 μL of the dispersion was then drop-coated onto a glassy carbon electrode. After the first dispersion dried, another 2.5 μL of the dispersion was drop-coated onto the glassy carbon electrode (3 mm in diameter). The electrode was dried at room temperature for 12 h before measurement.

[0067] Hydrogen evolution reaction (HER) test:

[0068] In a 0.5 M H2SO4 electrolyte solution saturated with H2, using a carbon rod as the counter electrode and a saturated calomel electrode as the reference electrode, the oxygen-linked single-atom oxide transition metal catalyst Mo-ZrO prepared in Example 1 was applied. 2-x / NG was used as the working electrode to form a three-electrode system for testing HER performance. Linear sweep voltammetry (LSV) was performed at a scan rate of 50 mV / s. All potentials needed to be converted to the standard hydrogen electrode (RHE), with the corresponding formula: E(RHE) = E(SCE) + (0.242 + 0.059 pH).

[0069] In a 1.0 M KOH electrolyte solution saturated with H2, a carbon rod was used as the counter electrode, a saturated calomel electrode as the reference electrode, and the oxygen-linked single-atom oxide transition metal catalyst prepared in Example 1 was used as the working electrode to form a three-electrode system for testing HER performance. Linear sweep voltammetry (LSV) was performed at a scan rate of 50 mV / s. All potentials needed to be converted to the standard hydrogen electrode (RHE), corresponding to the formula: E(SCE) + (0.242 + 0.059 pH).

[0070] Anion exchange membrane electrolyzer test: First, catalyst ink was prepared by mixing 10 mg of electrocatalyst, 2000 μL of isopropanol, 200 μL of ultrapure water, and 200 μL of PiperION-B5-HCO3 solution (5 wt%) and sonicating for 2 hours. Then, the catalyst ink was drop-coated onto one side of carbon paper (Toray H060), with an electrode area of ​​2*2 cm. 2 . Using Mo-ZrO 2-x / NG was used as the cathode catalyst, and the final catalyst loading was 1.0 mg cm⁻¹. -2 IrO2 (Sigma-Aldrich) was used as the anode catalyst, with a loading of 1 mg / cm³. -2 The prepared carbon paper containing anode and cathode catalysts was placed in an anion exchange membrane. X37-50 grade 60 (Suzhou Shengernuo Technology) underwent polarization curve and stability testing. During the test, the flow drop at the H2 and O2 ends remained at 0.3 L / min. -1 The stability of the anion exchange membrane was evaluated under a constant battery voltage of 0.3V.

[0071] like Figure 1 As shown, this is the Mo-ZrO prepared in Example 1. 2-x XRD patterns of / NG confirm ZrO 2-x The XRD peaks match well with those of t-type ZrO2, indicating that Mo exists in single-atom form.

[0072] like Figure 2 As shown, this is the Mo-ZrO prepared in Example 1. 2-x The Raman spectrum of / NG, in the Raman spectrum, Mo-ZrO 2-x The intensity ratio of the D band to the G band of / NG (I D / I G The value of 1.10 indicates that more defects are introduced into the N-doped graphene lattice.

[0073] like Figure 3 As shown, this is the Mo-ZrO prepared in Example 1. 2-x / NG infrared spectrum, Mo-ZrO 2-x / NG possesses abundant functional groups, including hydroxyl (-OH) functional groups, which can adsorb water molecules through hydrogen bonding and other interactions, making it easier for water molecules to accumulate on the catalyst surface, thereby increasing reactant concentration and accelerating the reaction rate. Conjugated carbon-carbon double bonds (C=C) can construct an electron delocalization system within the material. In the hydrogen evolution reaction, good conductivity ensures rapid electron transport from the electrode to the active site of the catalyst, promoting the proton reduction reaction (2H+). + +2e - →H2), thereby improving the kinetic performance of the hydrogen evolution reaction.

[0074] Figure 4 a and 4b are Mo-ZrO prepared in Example 1, respectively. 2-x / NG low-magnification and high-magnification TEM images, Mo-ZrO 2-x / NG exhibits a structure with abundant folds and ripples, thus providing a large specific surface area and exposing more active sites.

[0075] like Figure 5 As shown, this is the Mo-ZrO prepared in Example 1. 2-x HAADF-STEM image of / NG, showing Mo uniformly loaded in ZrO in the form of single atoms. 2-x On the cluster.

[0076] like Figure 6 As shown, this is the Mo-ZrO prepared in Example 1. 2-x The elemental composition diagram of / NG shows that Zr: 2.28, Mo: 6.27, C: 76.48, N: 9.38, O: 5.59, indicating that each element has been successfully doped into graphene.

[0077] like Figure 7 As shown, this is the Mo-ZrO prepared in Example 1. 2-x The XPS plot of / NG shows three pairs of deconvolution peaks in the Mo 3d spectrum. Two pairs of binding energies, 231.7 / 229.1 and 232.9 / 236.0 eV, are attributed to Mo.4+ and Mo 6+ This proves the existence of the Mo-O bond, where 232.1 / 230.3 belongs to Mo. 2+ Mo 3d confirms the coexistence of multiple valence states of Mo. Zr 3d shows that Zr exists in Zr valence states. 4+ and Zr 3+ The coexistence of these forms demonstrates that ZrO2 possesses abundant defects. Furthermore, in the O 1s spectrum, 530.4, 531.1, 531.9, and 533.2 eV are attributed to metallic O (Mo-O / Zr-O), V, and E, respectively. O The presence of CO and OH confirmed the existence of Mo-O and Zr-O. These results demonstrate the interaction between Mo single atoms and ZrO. 2-x They are tightly bound together by oxygen bridges. For the deconvolution N1s spectrum, pyridine N (398.6 eV), pyridine N (400.0 eV), and graphitic N (401.7 eV), Mo-N (397.0 eV) confirmed the coordination of Mo atoms with N atoms. Furthermore, changes in the N configuration are beneficial for optimizing the local electronic structure.

[0078] like Figure 8 Figures a and 8c show the polarization curves of this composite material as a catalyst in 0.5H₂SO₄ electrolyte and 1.0M KOH electrolyte, respectively. It can be seen that the current density of this catalyst in acidic and alkaline electrolytes is 10 mA / cm². -2 The low overpotentials at those times are 22 and 23 mV, respectively. (From...) Figure 8 Figures b and 8d show that the composite material prepared in this invention has low Tafel slopes in both acidic and alkaline electrolytes, at 31 and 32 mV / dec, respectively, demonstrating that the catalyst exhibits good hydrogen evolution catalytic activity under acidic conditions.

[0079] like Figure 9 Figure a shows the cycling curves of the catalyst prepared in Example 1 in hydrogen-saturated 0.5 H₂SO₄ and 1.0 M KOH solutions. After 10,000 cycles, the decrease in catalyst performance is negligible, demonstrating that the prepared catalytic material has excellent cycling stability. Figure 9 Figure b shows the long-term stability test of the catalyst prepared in this invention under constant current in hydrogen-saturated 0.5 H₂SO₄ solution and 1.0 M KOH solution. It can be seen that after 30 hours of testing under constant current, the polarization current of the material prepared in this invention shows almost no decrease compared to the initial value, demonstrating good long-term stability.

[0080] like Figure 10Figures a and 10c show the polarization curves of this composite material as a catalyst in 0.5H₂SO₄ and 1.0M KOH seawater, respectively. It can be seen that the current density of this catalyst in acidic and alkaline seawater electrolytes is 10 mA / cm². -2 The overvoltages are 36 and 29 mV, respectively. (From...) Figure 10 Figures b and 10d show that the composite material prepared in this invention exhibits low Tafel slopes in both acidic and alkaline seawater, at 35 and 34 mV dec, respectively. -1 This demonstrates that the catalyst exhibits good hydrogen evolution catalytic activity under seawater conditions.

[0081] like Figure 11 As shown, the Mo-ZrO prepared in Example 1 2-x Polarization curves of the / NG catalyst in an anion exchange membrane electrolyzer. Using the above catalyst as the cathode catalyst in the anion exchange membrane electrolyzer at 70°C and a current density of 0.5 A / cm². 2 Under these conditions, only a voltage of 1.93V is required.

[0082] like Figure 12 As shown, the Mo-ZrO prepared in Example 1 2-x / NG catalyst was used in an anion exchange membrane electrolyzer (1.0 MkOH electrolyte) at a constant current density of 0.3 A / cm². -2 After 60 hours of continuous operation, its voltage decay rate is negligible, indicating that Mo-ZrO 2-x / NG exhibits both high activity and long-term stability in alkaline water electrolysis systems, demonstrating that this catalyst not only displays excellent catalytic activity and stability but also shows great potential in practical applications and has promising application prospects.

Claims

1. A process for the preparation of an oxygen-attached monoatomic-oxide transition metal catalyst, characterized by, The method comprises the following steps: S1, adding a molybdenum source into a graphene oxide solution, then adding a zirconium source and stirring to obtain a precursor solution, and performing a hydrothermal reaction on the precursor solution to obtain a reaction product; S2, drying the reaction product, and then performing high-temperature nitridation by a chemical vapor deposition method to obtain an oxygen-attached monatomic-oxide transition metal catalyst.

2. The production method according to claim 1, characterized by, The molybdenum in the molybdenum source accounts for 5-15% of the mass percentage of the graphene oxide; and the zirconium in the zirconium source accounts for 3-7% of the mass percentage of the graphene oxide.

3. The production method according to any one of claims 1 or 2, characterized in that, The molybdenum source is ammonium molybdate tetrahydrate; and the zirconium source is zirconium tetrachloride.

4. The production method according to claim 1, characterized by, In step S1, the concentration of the graphene oxide solution is 1-3 mg / mL.

5. The preparation method according to claim 1, characterized in that, In step S1, the temperature of the hydrothermal reaction is 160-220°C, and the time of the hydrothermal reaction is 8-24 h.

6. The method of claim 1, wherein, In step S2, the drying treatment is freeze-drying, and the time of the freeze-drying is 6-12 h.

7. The preparation method according to claim 1, characterized in that, In step S2, the high-temperature nitridation by the chemical vapor deposition method comprises the following steps: performing nitridation under a mixed atmosphere of argon and ammonia, the reaction temperature is 600-1000°C, the reaction time is 1-3 h, the argon flow rate is 100±10 sccm, and the ammonia flow rate is 50±10 sccm.

8. An oxygen-attached monatomic-oxide transition metal catalyst prepared by the method of any one of claims 1-7.

9. Use of the oxygen-attached monatomic-oxide transition metal catalyst of claim 8 as a catalyst for an electrocatalytic hydrogen evolution reaction.

10. Use of the oxygen-attached monatomic-oxide transition metal catalyst of claim 8 as a cathode catalyst for an anion exchange membrane.

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