Transition metal catalyst with Mo-Ru double sites as well as preparation method and application of transition metal catalyst

Abstract

The invention relates to a transition metal catalyst with Mo-Ru double sites and a preparation method thereof.The preparation method comprises the following steps that a mixed solution of a ruthenium source and a molybdenum source is added into a graphene oxide solution, then ultrasonic treatment is conducted for 30 min, a precursor solution is obtained, the precursor solution is subjected to a hydrothermal reaction, and a reaction product is obtained; and carrying out freeze drying treatment on the reaction product, and then carrying out high-temperature nitridation by adopting a chemical vapor deposition method to obtain the Mo-Ru double-site transition metal catalyst. The prepared transition metal catalyst with Mo-Ru double sites shows excellent two-electron hydrogen evolution reaction electro-catalytic performance in acidic and alkaline environments, and is high in activity and stable in performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical catalysis, and particularly relates to a transition metal catalyst with a Mo-Ru dual site, a preparation method and an application thereof. Background Art

[0002] With the rise of a global low-carbon circular economy, hydrogen production by water splitting is gaining increasing attention. Hydrogen, with its advantages of high energy density, low molecular weight, zero carbon emissions, and cleanliness, is considered an ideal carrier for future energy storage and supply and a vital chemical raw material in modern industrial production. To date, platinum-based materials have been considered effective electrocatalysts for the HER, but the large-scale commercialization of platinum-based catalysts faces the problem of high costs. Therefore, finding reasonably priced platinum-based catalysts is key to addressing the high cost of platinum-based catalysts. To date, Ru-based catalysts are considered one of the most promising alternatives to platinum-based materials for HER activity. However, due to the high binding energy of Ru atoms, irreversible aggregation of Ru atoms occurs during the actual catalytic process, resulting in unsatisfactory catalyst stability. In practical applications, the performance of Ru-based catalysts still needs to be further optimized, and therefore, there is an urgent need to dope them with foreign metals such as Mo to regulate the adsorption behavior of intermediates to achieve excellent activity and stability. Summary of the Invention

[0003] The purpose of the present invention is to provide a transition metal catalyst with a Mo-Ru dual site, a preparation method and application thereof, and solve the technical problem that the Mo-Ru dual site coordination structure is difficult to control;

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A transition metal catalyst having a Mo-Ru dual site and a preparation method and application thereof, comprising the following steps:

[0006] S1. Adding a mixed solution of ammonium heptamolybdate tetrahydrate and ruthenium chloride trihydrate to the graphene oxide solution, and then sonicating for 30 minutes to obtain a homogeneous precursor solution, and subjecting the precursor solution to a hydrothermal reaction to obtain a black columnar reaction product;

[0007] S2. The reaction product is freeze-dried and then subjected to high-temperature nitridation using a chemical vapor deposition method to obtain a transition metal catalyst having a Mo-Ru dual site.

[0008] Preferably, the percentage of ruthenium in the ruthenium chloride trihydrate to the mass of the graphene oxide in the graphene oxide solution is 1-10%; the percentage of molybdenum in the ammonium heptamolybdate tetrahydrate to the mass of the graphene oxide in the graphene oxide solution is 1-10%, wherein deionized water is used to dissolve the ruthenium chloride trihydrate and the ammonium heptamolybdate tetrahydrate.

[0009] Preferably, the preparation method of the graphene oxide solution is: dissolving graphene oxide solid in deionized water, ultrasonicating for 4-6 h to obtain a uniformly dispersed graphene oxide solution; the concentration of the graphene oxide solution is 1-3 mg mL -1 .

[0010] Preferably, in step S1, the ultrasonic time is 30 min.

[0011] Preferably, in step S1, the temperature of the hydrothermal reaction is 170-190° C., and the time of the hydrothermal reaction is 8-14 h.

[0012] Preferably, in step S2, the freeze-drying treatment time is 5-10 h.

[0013] Preferably, in step S2, the high-temperature nitridation using a chemical vapor deposition method includes the following steps: nitridation is performed in a mixed atmosphere of argon and ammonia, with a reaction temperature of 700-900°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.

[0014] In another aspect, the present invention provides a transition metal catalyst having a Mo-Ru dual site, which is prepared using the above-mentioned preparation method.

[0015] In another aspect, the present invention provides use of the above-mentioned transition metal catalyst having Mo-Ru dual sites as a catalyst for a two-electron hydrogen evolution reaction.

[0016] In another aspect of the present invention, the above-mentioned transition metal catalyst having Mo-Ru dual sites is provided for use as an electrocatalyst in hydrogen production by electrolysis of water.

[0017] The present invention uses ruthenium chloride trihydrate (RuCl3·3H2O) as a ruthenium source, ammonium heptamolybdate tetrahydrate ((NH4)6Mo7O 24 A Mo-Ru dual-site transition metal catalyst was synthesized by hydrothermal synthesis and chemical vapor deposition (CVD) using 4H2O) as a molybdenum source and ammonia (NH3) as a nitrogen source. The catalyst exhibited excellent electrocatalytic performance for the two-electron hydrogen evolution reaction (HER) in both acidic and alkaline environments.

[0018] The present invention uses graphene as a carrier and potassium hydroxide as a pH regulator for the graphene suspension in a hydrothermal reaction, which not only provides a large amount of positive charge for the graphene nanosheets but also facilitates the formation of Ru-O-Mo structure. In the hydrothermal reaction, [MoO4(H2O)2] 2−The O-coordinated RuMo3 groups act as O,O'-bidentate ligands. Due to the strong coupling between the negatively charged RuMo3 groups and the positively charged protonated p-RGO sheets, the O-coordinated RuMo3 groups are electrostatically attracted to the p-RGO sheets. During the CVD process, nitrogen doping and further reduction of the p-RGO occur simultaneously, forming RuMo3 groups anchored within the p-RGO sheets, thereby constructing a Ru-O-Mo-N-C structure.

[0019] The synthesis method of the present invention is simple, the preparation cycle is short, the precursor is cheap and the reserves are abundant, and it has good application prospects; the transition metal catalyst with Mo-Ru dual sites can be obtained by simple hydrothermal and chemical vapor deposition, and the above-mentioned transition metal catalyst with Mo-Ru dual sites is provided as a catalyst for the development of high-efficiency and low-cost electrocatalysts to support the application of renewable energy-driven water electrolysis hydrogen production technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the XRD pattern of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1;

[0021] Figure 2 This is a Raman spectrum of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1;

[0022] Figure 3 This is an infrared spectrum of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1;

[0023] Figure 4 TEM image of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1, where a is 500 nm and b is 200 nm;

[0024] Figure 5 Schematic diagram of the element content of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1;

[0025] Figure 6 This is the XPS pattern of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1, where a is Mo 3d, b is Ru 3p, c is N 1s, and d is O 1s;

[0026] Figure 7 The acidic and basic HER performances of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1 are shown, wherein: a is the polarization curve, and b is the corresponding Tafel slope plot;

[0027] Figure 8The electrochemical double layer capacitance (C dl );

[0028] Figure 9 is the turnover frequency (TOF) of each active site of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1;

[0029] Figure 10 The transition metal catalyst with Mo-Ru dual sites prepared in Example 1 produced a smaller charge transfer resistance (Rct) in 0.5 M H2SO4 and 1.0 M KOH seawater solutions;

[0030] Figure 11 This is a long-term potential stability test of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1. DETAILED DESCRIPTION

[0031] The present invention is further described below with reference to the accompanying drawings and specific embodiments.

[0032] The graphene oxide in the following examples was prepared by a modified Hummers method, as follows: 3 g of graphite powder and a mixed solution of concentrated H2SO4 and H3PO4 (volume ratio 9:1) were added to a three-necked flask, and 18 g of KMnO4 solid was slowly added at a rotation speed of 200-350 rpm.

[0033] The water bath temperature was set at 50°C, the stirring speed was 200-350 rpm, and the stirring time was 12 h. After the reaction, the solution temperature dropped to room temperature, poured into 400 mL of pre-chilled 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 repeatedly washed with 30% by mass HCl solution, deionized water, anhydrous ethanol, and ether. After vacuum drying at room temperature for 24 h, a light yellow graphene oxide solid was obtained.

[0034] Example 1

[0035] A method for preparing a transition metal catalyst having a Mo-Ru dual site, comprising the following steps:

[0036] 0.16 g of graphene oxide solid was added to 80 ml of deionized water. After ultrasonication for 6 h, 7 mL of ruthenium chloride trihydrate solution and 4 mL of ammonium heptamolybdate tetrahydrate solution were added to the graphene oxide solution in sequence, where the mass of ruthenium and molybdenum elements accounted for 7% and 4% of the mass of graphene oxide, respectively. After ultrasonication for 10 min, a uniformly dispersed precursor solution was obtained.

[0037] The precursor solution was transferred to the inner lining of the reactor, and the hydrothermal temperature was set to 180 °C and the hydrothermal time was set to 12 h.

[0038] After freeze-drying the hydrothermal product for 10 hours, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction in a mixed atmosphere of Ar and NH₃ using chemical vapor deposition technology. The reaction parameters were set as follows: temperature: 800°C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, and nitridation time: 2 hours. This resulted in a transition metal catalyst with a Mo-Ru dual site (MoRu-NG).

[0039] Example 2

[0040] A method for preparing a transition metal catalyst having a Mo-Ru dual site, comprising the following steps:

[0041] 0.16 g of graphene oxide solid was added to 80 ml of deionized water. After ultrasonication for 6 h, 7 mL of ruthenium chloride trihydrate solution and 1 mL of ammonium heptamolybdate tetrahydrate solution were added to the graphene oxide solution in sequence, where the mass of ruthenium and molybdenum elements accounted for 7% and 1% of the mass of graphene oxide, respectively. After ultrasonication for 10 min, a uniformly dispersed precursor solution was obtained.

[0042] The precursor solution was transferred to the inner lining of the reactor, and the hydrothermal temperature was set to 180 °C and the hydrothermal time was set to 12 h.

[0043] After freeze-drying the hydrothermal product for 10 hours, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction in a mixed atmosphere of Ar and NH₃ using chemical vapor deposition technology. The reaction parameters were set as follows: temperature: 800°C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, and nitridation time: 2 hours. This resulted in a transition metal catalyst (MoRu-NG-1) with a Mo-Ru dual site.

[0044] Example 3

[0045] A method for preparing a transition metal catalyst having a Mo-Ru dual site, comprising the following steps:

[0046] 0.16 g of graphene oxide solid was added to 80 ml of deionized water. After ultrasonication for 6 h, 7 mL of ruthenium chloride trihydrate solution and 8 mL of ammonium heptamolybdate tetrahydrate solution were added to the graphene oxide solution in sequence, where the mass of ruthenium and molybdenum elements accounted for 7% and 8% of the mass of graphene oxide, respectively. After ultrasonication for 10 min, a uniformly dispersed precursor solution was obtained.

[0047] The precursor solution was transferred to the inner lining of the reactor, and the hydrothermal temperature was set to 180 °C and the hydrothermal time was set to 12 h.

[0048] After freeze-drying the hydrothermal product for 10 hours, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction in a mixed atmosphere of Ar and NH₃ using chemical vapor deposition technology. The reaction parameters were set as follows: temperature: 800°C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, and nitridation time: 2 hours. A transition metal catalyst (MoRu-NG-8) with a Mo-Ru dual site was obtained.

[0049] Example 4

[0050] A method for preparing a transition metal catalyst having a Mo-Ru dual site, comprising the following steps:

[0051] 0.16 g of graphene oxide solid was added to 80 ml of deionized water. After ultrasonication for 6 h, 7 mL of ruthenium chloride trihydrate solution and 4 mL of ammonium heptamolybdate tetrahydrate solution were added to the graphene oxide solution in sequence, where the mass of ruthenium and molybdenum elements accounted for 7% and 4% of the mass of graphene oxide, respectively. After ultrasonication for 10 min, a uniformly dispersed precursor solution was obtained.

[0052] The precursor solution was transferred to the inner lining of the reactor, and the hydrothermal temperature was set to 180 °C and the hydrothermal time was set to 12 h.

[0053] After freeze-drying the hydrothermal product for 10 hours, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction in a mixed atmosphere of Ar and NH₃ using chemical vapor deposition technology. The reaction parameters were set as follows: temperature: 800°C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, and nitridation time: 1 hour. This resulted in a transition metal catalyst (MoRu-NG@1) with a Mo-Ru dual site.

[0054] Example 5

[0055] A method for preparing a transition metal catalyst having a Mo-Ru dual site, comprising the following steps:

[0056] 0.16 g of graphene oxide solid was added to 80 ml of deionized water. After ultrasonication for 6 h, 7 mL of ruthenium chloride trihydrate solution and 4 mL of ammonium heptamolybdate tetrahydrate solution were added to the graphene oxide solution in sequence, where the mass of ruthenium and molybdenum elements accounted for 7% and 4% of the mass of graphene oxide, respectively. After ultrasonication for 10 min, a uniformly dispersed precursor solution was obtained.

[0057] The precursor solution was transferred to the inner lining of the reactor, and the hydrothermal temperature was set to 180 °C and the hydrothermal time was set to 12 h.

[0058] After freeze-drying the hydrothermal product for 10 hours, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction in a mixed atmosphere of Ar and NH₃ using chemical vapor deposition technology. The reaction parameters were set as follows: temperature: 800°C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, and nitridation time: 3 hours. This resulted in a transition metal catalyst with a Mo-Ru dual site (MoRu-NG@3).

[0059] Example 6

[0060] A method for preparing a transition metal catalyst having a Mo-Ru dual site, comprising the following steps:

[0061] 0.16 g of graphene oxide solid was added to 80 ml of deionized water. After ultrasonication for 6 h, 7 mL of ruthenium chloride trihydrate solution and 4 mL of ammonium heptamolybdate tetrahydrate solution were added to the graphene oxide solution in sequence, where the mass of ruthenium and molybdenum elements accounted for 7% and 4% of the mass of graphene oxide, respectively. After ultrasonication for 10 min, a uniformly dispersed precursor solution was obtained.

[0062] The precursor solution was transferred to the inner lining of the reactor, and the hydrothermal temperature was set to 180 °C and the hydrothermal time was set to 12 h.

[0063] After freeze-drying the hydrothermal product for 10 hours, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction in a mixed atmosphere of Ar and NH₃ using chemical vapor deposition technology. The reaction parameters were set as follows: temperature: 700°C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, and nitridation time: 2 hours. A transition metal catalyst with Mo-Ru dual sites (MoRu-NG / 700°C) was obtained.

[0064] Example 7

[0065] A method for preparing a transition metal catalyst having a Mo-Ru dual site, comprising the following steps:

[0066] 0.16 g of graphene oxide solid was added to 80 ml of deionized water. After ultrasonication for 6 h, 7 mL of ruthenium chloride trihydrate solution and 4 mL of ammonium heptamolybdate tetrahydrate solution were added to the graphene oxide solution in sequence, where the mass of ruthenium and molybdenum elements accounted for 7% and 4% of the mass of graphene oxide, respectively. After ultrasonication for 10 min, a uniformly dispersed precursor solution was obtained.

[0067] The precursor solution was transferred to the inner lining of the reactor, and the hydrothermal temperature was set to 180 °C and the hydrothermal time was set to 12 h.

[0068] After freeze-drying the hydrothermal product for 10 hours, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction in a mixed atmosphere of Ar and NH₃ using chemical vapor deposition technology. The reaction parameters were set as follows: temperature: 900°C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, and nitridation time: 2 hours. A transition metal catalyst with a Mo-Ru dual site (MoRu-NG / 900°C) was obtained.

[0069] Example 8

[0070] A method for preparing a transition metal catalyst having a Mo-Ru dual site, comprising the following steps:

[0071] 0.16 g of graphene oxide solid was added to 80 ml of deionized water. After ultrasonication for 6 h, 2 mL of ruthenium chloride trihydrate solution and 4 mL of ammonium heptamolybdate tetrahydrate solution were added to the graphene oxide solution in sequence, where the mass of ruthenium and molybdenum elements accounted for 2% and 4% of the mass of graphene oxide, respectively. After ultrasonication for 10 min, a uniformly dispersed precursor solution was obtained.

[0072] The precursor solution was transferred to the inner lining of the reactor, and the hydrothermal temperature was set to 180 °C and the hydrothermal time was set to 12 h.

[0073] After freeze-drying the hydrothermal product for 10 hours, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction in a mixed atmosphere of Ar and NH₃ using chemical vapor deposition technology. The reaction parameters were set as follows: temperature: 800°C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, and nitridation time: 2 hours. This resulted in a transition metal catalyst (MoRu-NG-2) with a Mo-Ru dual site.

[0074] Example 9

[0075] A method for preparing a transition metal catalyst having a Mo-Ru dual site, comprising the following steps:

[0076] 0.16 g of graphene oxide solid was added to 80 ml of deionized water. After ultrasonication for 6 h, 10 mL of ruthenium chloride trihydrate solution and 4 mL of ammonium heptamolybdate tetrahydrate solution were added to the graphene oxide solution in sequence, where the mass of ruthenium and molybdenum elements accounted for 10% and 4% of the mass of graphene oxide, respectively. After ultrasonication for 10 min, a uniformly dispersed precursor solution was obtained.

[0077] The precursor solution was transferred to the inner lining of the reactor, and the hydrothermal temperature was set to 180 °C and the hydrothermal time was set to 12 h.

[0078] After freeze-drying the hydrothermal product for 10 hours, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction in a mixed atmosphere of Ar and NH₃ using chemical vapor deposition technology. The reaction parameters were set as follows: temperature: 800°C, gas flow rate: NH₃: 50 sccm, Ar: 100 sccm, and nitridation time: 2 hours. This resulted in a transition metal catalyst (MoRu-NG-10) with a Mo-Ru dual site.

[0079] The catalyst performance evaluation and characterization of Example 1 are as follows:

[0080] The use of transition metal catalysts with Mo-Ru dual sites as 2e - Electrochemical testing of the HER catalyst materials was performed using a CHInstruments 760E electrochemical workstation in a three-electrode cell system. First, 2 mg of the catalyst was ultrasonically dispersed in 40 μL of a 5 wt% Nafion solution and 0.5 mL of a 4:1 v / v deionized water / ethanol solution to prepare a catalyst dispersion. A Pt / C catalyst dispersion (20 wt% Pt on graphitized carbon, Johnson Matthey) was prepared using the same method. 10 μL of this catalyst dispersion was then drop-coated onto a CFP (1 cm × 1 cm) working electrode, or 5 μL onto a glassy carbon electrode (3 mm diameter). The electrodes were dried at room temperature for 24 h. A graphite rod served as the counter electrode, and a saturated calomel electrode (SCE) served as the reference electrode. All potentials were referenced to the reversible hydrogen electrode (RHE): ERHE = ESCE + (0.242 + 0.059 pH) V, and all data were obtained without iR compensation. At room temperature, the 50 mV s −1 The polarization curves were obtained at a scan rate of 10 . –2 to 10 6 Before all tests, the electrochemical reaction cell was purged with H2 bubbles for 30 min.

[0081] Three-electrode system: platinum wire electrode as counter electrode, Ag / AgCl (3 M KCl solution as salt bridge) as reference electrode, glassy carbon electrode coated with transition metal catalyst with Mo-Ru dual site as working electrode. Before the experiment, nitrogen or oxygen was introduced into 0.1 M KOH electrolyte until saturated, and the reaction temperature was 100 mV s -1The cyclic voltammetry (CV) test was performed for 30–60 min until the catalyst surface was free of air. In an oxygen-saturated electrolyte, different speeds (225–2025 rpm) were set, and the voltage range was 0.1–1.1 V at a rate of 5 mV s -1 Linear voltammetry (LSV) was performed at a low sweep rate.

[0082] Figure 1 Shown is the XRD pattern of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1. The Ru nanocrystal peak was detected, but the peak of molybdenum-related substances was not detected, indicating that the molybdenum element exists in the lattice of graphite carbon in the form of isolated atoms or clusters.

[0083] Figure 2 The Raman spectrum of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1 is shown. In the Raman spectrum, the intensity ratio of the D band to the G band of MoRu-NG (I D / I G ) is 1.15. This result indicates that structural defects are introduced into MoRu-NG through the synergistic effect of Mo and Ru atoms and that more structural defects can be introduced by adjusting the atomic mass ratio to a suitable value.

[0084] Figure 3 The figure shows the infrared spectrum of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1. MoRu-NG has abundant functional groups, such as C−N and C−O groups, which effectively alleviate the inherent inertness of the graphene basal surface.

[0085] Figure 4 a and 4b are the low-magnification and high-magnification TEM images of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1, respectively. The morphology of MoRu-NG presents an ultrathin nanosheet structure with abundant wrinkles and ripples, which is conducive to the adsorption and activation of hydrogen in the HER process.

[0086] Figure 5 The figure shows the element content of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1, wherein Mo: 0.41, Ru: 0.96, C: 92.33, N: 0.78, O: 5.78, indicating that molybdenum, ruthenium, and nitrogen elements are successfully doped into graphene.

[0087] Figure 6 The XPS graph of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1 is shown. The Mo 3d spectrum of MoRu-NG shows three pairs of peaks, representing Mo(VI), Mo(V) and Mo-N species ( Figure 6 a). For the Ru3p spectrum of MoRu-NG ( Figure 6b), two pairs of peaks appeared for Ru species, corresponding to Ru(0) and Ru(IV), respectively

[30] , indicating the presence of Ru crystals on the MoRu-NG surface. Figure 6 c It can be seen that the deconvolution peaks near 531.0 eV and 530.3 eV are assigned to Mo-O and Ru-O bonds, respectively; compared with Mo-NG and Ru-NG, the Mo-O and Ru-O bonds of MoRu-NG are shifted by 0.3 eV toward higher binding energy. In the N 1s spectrum, pyridinic N (398.3 eV), pyrrolic-N (399.8 eV), graphitic-N (401.7 eV), Mo-N (394.6 eV), and NO (404.3 eV) only appear in MoRu-NG ( Figure 6 d), indicating that the Mo atoms are coordinated with the N atoms.

[0088] Figure 7 The figure shows the transition metal catalyst with Mo-Ru dual sites prepared in Example 1. In 0.5 M H2SO4 seawater solution, MoRu-NG can provide -10 mA cm -2 The geometric current density is very low, with an overpotential of 53 mV (η 10 = 53mV) Figure 7 a). In 0.5 M H2SO4 seawater solution, the Tafel slope of MoRu-NG is small, 30 mV dec. -1 ( Figure 7 b). In 1.0 M KOH seawater solution, MoRu-NG has the best activity, showing a higher current density at a lower overpotential than Mo-NG, Ru-NG, NG, and Pt / C ( Figure 7 c). MoRu-NG only needs an overpotential of 28 mV to reach -10 mAcm -2 The Tafel slope in 1.0 M KOH seawater solution is very low, 37 mV dec -1 ( Figure 7 d).

[0089] Figure 8 The figure shows the transition metal catalyst with Mo-Ru dual sites prepared in Example 1. The electrochemical double layer capacitance (C dl ). In 0.5 M H2SO4 seawater solution, the C dl The value is 18.3mF cm -2 ( Figure 8 ).

[0090] Figure 9The figure shows the transition metal catalyst with Mo-Ru dual sites prepared in Example 1. To further understand its intrinsic catalytic activity, the turnover frequency (TOF) of each active site was measured. Therefore, the number of active sites can be estimated by the integrated charge titration of anodic CV cycles in phosphate buffer solution (pH = 7). It can be seen that the TOF values ​​of MoRu-NG at η = 100 mV in acidic and alkaline electrolytes are 3.85 and 7.8 H2 s, respectively. -1 .

[0091] Figure 10 The figure shows the electrochemical impedance spectroscopy (EIS) technique of the transition metal catalyst with Mo-Ru dual sites prepared in Example 1. MoRu-NG produces a small charge transfer resistance (Rct) of 3 and 5 ohms in 0.5 M H2SO4 and 1.0 M KOH seawater solutions.

[0092] Figure 11 The figure shows the transition metal catalyst with Mo-Ru dual sites prepared in Example 1. At room temperature (25°C), the current density was -100, -200 and -300 mA cm -2 Several long-term potential stability tests of MoRu-NG were conducted using galvanostatic measurements. After operating for 100,000 seconds at j = -100, -200, and -300 mA cm⁻², the potential of MoRu-NG increased by only 24, 20, and 33 mV in 0.5 M H₂SO₄ seawater solution, and by 14, 10, and 42 mV in 1.0 M KOH seawater solution.

Claims

1. A method for preparing a transition metal catalyst having a Mo-Ru dual site, characterized in that: The following steps are involved: S1. Adding a mixed solution of a ruthenium source and a molybdenum source to a graphene oxide solution, then ultrasonicating to obtain a precursor solution, and subjecting the precursor solution to a hydrothermal reaction to obtain a reaction product; S2. The reaction product is freeze-dried and then subjected to high-temperature nitridation using a chemical vapor deposition method to obtain a transition metal catalyst having a Mo-Ru dual site.

2. The preparation method according to claim 1, characterized in that The percentage of ruthenium in the ruthenium source to the mass of graphene oxide in the graphene oxide solution is 2-10%; the percentage of molybdenum in the molybdenum source to the mass of graphene oxide in the graphene oxide solution is 1-8%.

3. The preparation method according to claim 1 or 2, characterized in that The ruthenium source is ruthenium chloride trihydrate; the molybdenum source is ammonium heptamolybdate tetrahydrate.

4. The preparation method according to claim 1, characterized in that: In step S1, the ultrasonic time is 30 min.

5. The preparation method according to claim 1, characterized in that: In step S1, the temperature of the hydrothermal reaction is 170-190° C., and the time of the hydrothermal reaction is 8-14 h.

6. The preparation method according to claim 1, characterized in that: In step S2, the freeze-drying treatment time is 5-10 h.

7. The preparation method according to claim 1, characterized in that: In step S2, the high-temperature nitridation using the chemical vapor deposition method includes the following steps: nitridation is performed in a mixed atmosphere of argon and ammonia, the reaction temperature is 700-900°C, the reaction time is 1-3 hours, the argon flow rate is 100±10 sccm, and the ammonia flow rate is 50±10 sccm.

8. A transition metal catalyst having a Mo-Ru dual site, prepared by the preparation method according to any one of claims 1 to 8.

9. Use of the transition metal catalyst having Mo-Ru dual sites according to claim 8 as a catalyst for a two-electron hydrogen evolution reaction.

10. Use of the transition metal catalyst with Mo-Ru dual sites as claimed in claim 8 as an electrocatalyst for producing hydrogen by electrolysis of water.

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