Catalyst for producing hydrogen peroxide from marine water as well as preparation method and application of catalyst

Abstract

The invention provides a catalyst for producing hydrogen peroxide from marine water as well as a preparation method and application of the catalyst. According to the catalyst, carbon dots serve as a carrier of the catalyst, nickel is dispersed on the surfaces of the carbon dots in a monatomic form, and nickel monatomic is coordinated with nitrogen atoms of the carbon dots. The catalyst shows high activity, high selectivity (the highest Faraday efficiency gt, 98%) and excellent long-term stability on hydrogen peroxide prepared through two-electron oxygen reduction reaction in seawater or simulated seawater electrolyte, and an efficient and stable catalyst solution is provided for distributed synthesis of hydrogen peroxide through seawater resources.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials and new energy technology, and in particular relates to a catalyst for producing hydrogen peroxide from seawater, its preparation method, and its application. Background Technology

[0002] Hydrogen peroxide (H2O2) is a globally important chemical. As a versatile green oxidant, it is widely used in environmental remediation, pulp bleaching, and chemical synthesis, and also has the potential to serve as an energy carrier. However, industrial-scale H2O2 production currently relies heavily on the energy-intensive anthraquinone oxidation process. This process not only consumes organic solvents and precious metal catalysts but also poses challenges for distributed systems. Direct electrosynthesis of H2O2 via a two-electron oxygen reduction reaction has emerged as a promising sustainable alternative. This electrochemical method uses water and air as feedstock, can be powered by renewable energy sources, and enables modular, on-demand, and readily available H2O2 production.

[0003] 2e- used in the production of H2O2 - ORR (two-electron oxygen reduction reaction) involves two consecutive proton-coupled electron transfer steps, in which (Adsorbed peroxyhydroxyl group) is the only reaction intermediate. Although Dissociation is thermodynamically more favorable than the formation of H₂O₂, but nickel-based single-atom catalysts with isolated active sites have been shown to overcome this limitation. These sites restrict oxygen adsorption to end-pair configurations, thereby stabilizing the oxygen. The intermediate prevents the breaking of OO bonds. Furthermore, Ni's d-electron orbitals can achieve [interaction / relationships]. By optimizing the adsorption energy and balancing O2 activation and H2O2 desorption, the reaction is selectively guided towards a more efficient 2e-phase flow. - H2O generation path 2。

[0004] However, single metal atoms are prone to migration and aggregation during preparation or reaction, leading to deactivation; simultaneously, the complex ionic environment in seawater (such as Cl) - Carbon dots can easily erode catalytic sites, compromising their stability. Therefore, developing a novel carbon dot-based single-atom catalyst suitable for harsh seawater environments and its specific anchoring preparation method is of significant scientific and practical value. Summary of the Invention

[0005] In view of this, the present invention aims to provide a catalyst for hydrogen peroxide production from seawater, its preparation method, and its application, to overcome the shortcomings of the prior art and provide a structurally stable, clearly defined active site-specific, carbon-point-anchored nickel single-atom catalyst. This catalyst, in seawater or simulated seawater electrolyte, exhibits high activity for 2e⁻. -ORR-based H2O2 preparation exhibits high activity, high selectivity, and excellent long-term stability. Furthermore, this invention provides a specific preparation method for this catalyst, which enables the anchoring of nickel atoms on the carbon dot surface.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows: In the first aspect, a catalyst for producing hydrogen peroxide from seawater is provided, in which carbon dots serve as the catalyst support, nickel is dispersed on the surface of the carbon dots in the form of single atoms, and the nickel single atoms are coordinated with the nitrogen atoms of the carbon dots.

[0007] As a further embodiment, the surface of the carbon dots contains at least one nitrogen-containing functional group selected from amino, pyridine nitrogen, and graphitic nitrogen. As a further preferred embodiment, the carbon dot surface also contains at least one oxygen-containing functional group selected from carbonyl, carboxyl, and hydroxyl groups.

[0008] Secondly, the present invention provides a method for preparing a catalyst for producing hydrogen peroxide from seawater, comprising the following steps: 1) Dissolve the nickel salt, carbon dots, and nitrogen-containing organic ligands in deionized water and mix thoroughly to obtain a mixture; 2) The mixture obtained in step 1) is ultrasonically dispersed to allow nickel ions to fully coordinate with the nitrogen-containing functional groups on the surface of carbon dots, and then freeze-dried to obtain an aerogel precursor. 3) Collect the aerogel precursor from step 2), introduce a protective gas, and pyrolyze it at a specific temperature for a certain time to obtain a nickel single-atom catalyst, which is a catalyst for producing hydrogen peroxide from seawater.

[0009] As a further embodiment, in step 1), the nickel salt is one or more of nickel acetate tetrahydrate, nickel chloride, and nickel acetylacetone; and the nitrogen-containing organic ligand is one or more of bis(nitrile)amine, melamine, and urea.

[0010] As a further option, in step 1), the mass ratio of nickel salt, carbon dots and nitrogen-containing organic ligands is 1:(1~5):(10~30), and the content of nickel salt in deionized water is 0.1~2 mg / mL.

[0011] As a further option, in step 2), the ultrasonic dispersion frequency is 30~50kHz and the time is 10~120min; the freeze-drying temperature is -45~-55℃, the pressure is 1~20Pa, and the time is 12~36h.

[0012] As a further option, in step 3), the protective gas is argon or nitrogen, and the gas flow rate is 20~100cm. 3 The heating rate is 2-5°C / min, the pyrolysis temperature is 300-700°C, the heating rate is 2-5°C / min, and the heating time is 1-3h.

[0013] The method for preparing carbon dots in step 1) includes the following steps: Citric acid and urea were dissolved in ethylene glycol, stirred, heated, filtered, and dialyzed with deionized water as the external dialysis solution. The dialysate was freeze-dried to obtain carbon dot powder. The molar ratio of citric acid, urea, and ethylene glycol is 1:(1~3):(40~80); the heating temperature is 120~240℃, and the heating time is 2~24h; the diameter of the filter membrane used for filtration is 0.1~0.5μm; the volume of deionized water used as the dialysate for dialysis is 800~1500mL; the dialysis time is 2~72h; the dialysate is replaced 2~4 times every 24h; and the freeze-drying time is 12~48h. More preferably, the molar ratio of citric acid, urea, and ethylene glycol is 1:(1.5~2.5):(50~60); the heating time is 8~16h; and the dialysis time is 12~48h.

[0014] The carbon dots of the present invention can be prepared by the above method, or commercially available carbon dots can be used.

[0015] On the other hand, the present invention provides the application of the catalyst for producing hydrogen peroxide from seawater as described above, or the catalyst prepared by the preparation method as described above, in the electrocatalytic production of hydrogen peroxide.

[0016] As a further option, the electrolyte for electrocatalysis is seawater, simulated seawater, or an alkaline sodium chloride solution.

[0017] As a further approach, the operating current density for the electrocatalytic preparation of hydrogen peroxide is 10~200 mA / cm². 2 .

[0018] The pyridine nitrogen / pyrrole nitrogen or graphitic nitrogen species on the carbon dot surface can stabilize nickel single atoms via lone pair electrons. Furthermore, the abundant functional groups on the carbon dot surface provide numerous anchoring sites for chelation, inducing the formation of strong Ni-N bonds. X Coordinate bonds thermodynamically significantly enhance the migration energy barrier of Ni atoms, ensuring the stability of their atomically dispersed state and thus preventing the migration and aggregation of Ni atoms. Furthermore, high concentrations of Cl... - A localized high electric field can be formed on the catalyst surface, inducing Cl... - Direct discharge. This not only improves the efficiency of the shunt current, but more importantly, it reduces the oxidation products (such as the active chlorine species ClO). - HClO has strong nucleophilicity and can destroy the reactive oxygen intermediates on the catalyst surface through electrophilic attack, while poisoning the catalytic active sites and destroying their stability.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) For the first time, a Ni single-atom catalyst with carbon dots as the support was constructed, and the ultra-high stability anchoring of Ni single atoms was achieved through Ni-N coordination bonds; (2) The preparation method of the present invention, which combines carbon point anchoring and high-temperature pyrolysis, has a unique process, can effectively control the coordination environment of Ni, has good repeatability, and is easy to scale up; (3) The catalyst of the present invention, in actual seawater and simulated seawater electrolytes, exhibits high current density (10~200 mA / cm²) 2 The selectivity for H2O2 is higher than 85% (up to 95% or more), and it exhibits excellent long-term operational stability (performance degradation of less than 5% after 200 hours of continuous operation), far exceeding most of the non-precious metal catalysts reported in the present. (4) Directly utilizing abundant seawater resources as electrolytes reduces raw material costs and purification energy consumption, providing a brand-new technical solution for distributed H2O2 production at sea or in coastal areas. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the catalyst preparation process in Example 1 of the present invention.

[0021] Figure 2 This is a high-angle annular dark-field image of the catalyst in Example 1 of the present invention, taken under a spherical aberration-corrected scanning transmission electron microscope.

[0022] Figure 3 The image shows the characterization of the catalyst prepared in Example 1 of this invention, where a is the X-ray absorption near-edge structure (XANES) and b is the Fourier transform k3 weighted extended X-ray absorption fine structure (EXAFS).

[0023] Figure 4 Examples 1, 2, and 3 of this invention were prepared in simulated seawater (0.5 mol / L NaCl) at the same current density (30 mA / cm²). 2 Comparison of cumulative H2O2 production performance.

[0024] Figure 5 The yield of H2O2 and Faraday efficiency of Example 2 of the present invention under different current densities.

[0025] Figure 6 The data are measured on the rotating ring disk electrode in Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention; where a is the disk current and ring current polarization curve; b is the H2O2 selectivity and electron transfer number.

[0026] Figure 7 The catalyst prepared in Example 1 of this invention was subjected to a simulated seawater electrolyte at 30 mA / cm². 2Long-term stability test results at current density. Detailed Implementation

[0027] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0028] The present invention will be described in detail below with reference to the embodiments.

[0029] Example 1

[0030] This embodiment provides a method for preparing a carbon point-anchored nickel single-atom catalyst for electrocatalytic hydrogen peroxide production in seawater, comprising the following steps: Step 1: The preparation process of carbon dots is as follows: 0.615 g of citric acid and 0.385 g of urea were dissolved in 10 mL of ethylene glycol, stirred evenly, and then transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene. The reaction was carried out at 180 °C for 7 hours. After the reaction was completed, the mixture was allowed to cool naturally. The resulting brownish-yellow solution was dialyzed for 48 hours using a dialysis bag with a molecular weight cutoff of 1000 Da. The volume of deionized water used for dialysis was 1000 mL, and the dialysis fluid was changed twice every 24 hours. The solution was then continuously cold-dried at -55 °C and 10 Pa for 36 hours to obtain solid carbon dot powder.

[0031] Step 2: Weigh 14.2 mg of nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O) and 30 mg of carbon dot powder, dissolve them in 30 mL of deionized water, and ultrasonically disperse for 15 min. Then add 300 mg of dicyandiamide to the above solution, ultrasonically disperse for 30 min, and after uniform dispersion, rapidly freeze it with liquid nitrogen and place it in a vacuum freeze dryer at -55 °C and 10 Pa for 30 h to obtain a solid aerogel, i.e., an aerogel precursor. The ultrasonic dispersion frequency was 30~50 kHz.

[0032] Step 3: Transfer the solid aerogel to a tube furnace and heat it to 500 °C at a heating rate of 5 °C / min, and maintain this temperature for 2 h, keeping the temperature 80 cm² throughout the heating process. 3 An argon flow atmosphere of / min was maintained. After heating, the mixture was allowed to cool naturally to room temperature to obtain Ni single-atom catalyst powder, which is the catalyst used for hydrogen peroxide production from seawater.

[0033] Example 2

[0034] This embodiment provides a method for preparing a carbon point-anchored nickel single-atom catalyst for electrocatalytic hydrogen peroxide production in seawater, comprising the following steps: Step 1: The preparation process of carbon dots is as follows: 0.615 g of citric acid and 0.385 g of urea were dissolved in 10 mL of ethylene glycol, stirred evenly, and then transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene. The reaction was carried out at 180 °C for 7 hours. After the reaction was completed, the mixture was allowed to cool naturally. The resulting brownish-yellow solution was dialyzed for 48 hours using a dialysis bag with a molecular weight cutoff of 1000 Da. The volume of deionized water used for dialysis was 1000 mL, and the dialysis fluid was changed twice every 24 hours. The solution was then continuously cold-dried at -55 °C and 10 Pa for 36 hours to obtain solid carbon dot powder.

[0035] Step 2: Weigh 33 mg of nickel chloride hexahydrate (NiCl2·6H2O) and 100 mg of carbon dot powder, dissolve them in 30 mL of deionized water, and ultrasonically disperse for 30 min. Then add 400 mg of dicyandiamide to the above solution, ultrasonically disperse for 45 min, and after uniform dispersion, rapidly freeze it with liquid nitrogen and place it in a vacuum freeze dryer at -55 °C and 10 Pa for 30 h to obtain a solid aerogel, i.e., an aerogel precursor. The ultrasonic dispersion frequency was 30~50 kHz.

[0036] Step 3: Transfer the solid aerogel to a tube furnace and heat it to 550 °C at a heating rate of 5 °C / min, and maintain this temperature for 2 h, keeping the temperature 80 cm² throughout the heating process. 3 An argon flow atmosphere of / min was maintained. After heating, the mixture was allowed to cool naturally to room temperature to obtain Ni single-atom catalyst powder, which is the catalyst used for hydrogen peroxide production from seawater.

[0037] Example 3

[0038] This embodiment provides a method for preparing a carbon point-anchored nickel single-atom catalyst for electrocatalytic hydrogen peroxide production in seawater, comprising the following steps: Step 1: The preparation process of carbon dots is as follows: 0.615 g of citric acid and 0.385 g of urea were dissolved in 10 mL of ethylene glycol, stirred evenly, and then transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene. The reaction was carried out at 180 °C for 7 hours. After the reaction, the mixture was allowed to cool naturally. The resulting brownish-yellow solution was dialyzed for 48 hours using a dialysis bag with a molecular weight cutoff of 1000 Da. The volume of deionized water used for dialysis was 1000 mL, and the dialysis fluid was changed twice every 24 hours. The solution was then continuously cold-dried at -55 °C and 10 Pa for 36 hours to obtain solid carbon dot powder. The ultrasonic dispersion frequency was 30~50 kHz.

[0039] Step 2: Weigh 20 mg of nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O) and 40 mg of carbon dot powder, dissolve them in 30 mL of deionized water, and ultrasonically disperse for 60 min. Then add 280 mg of dicyandiamide to the above solution, stir continuously for 2 h, and after uniform dispersion, rapidly freeze it with liquid nitrogen and place it in a vacuum freeze dryer. Under conditions of -55 °C and 10 Pa, continue to freeze-dry for 30 h to obtain a solid aerogel, i.e., an aerogel precursor.

[0040] Step 3: Transfer the solid aerogel to a tube furnace and heat it to 450 °C at a heating rate of 5 °C / min, and maintain this temperature for 2 h, keeping a distance of 100 cm throughout the heating process. 3 An argon flow atmosphere of / min was maintained. After heating, the mixture was allowed to cool naturally to room temperature to obtain Ni single-atom catalyst powder, which is the catalyst used for hydrogen peroxide production from seawater.

[0041] Comparative Example 1 14.2 mg of nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O) was weighed and dissolved in 30 mL of deionized water. Then, 300 mg of dinitrileamine was added, and the mixture was ultrasonically dispersed for 30 min, stirred continuously for 2 h, and after uniform dispersion, it was rapidly frozen with liquid nitrogen and placed in a vacuum freeze dryer at -55 °C and 10 Pa for 30 h to obtain a solid aerogel. The solid aerogel was transferred to a tube furnace and heated to 500 °C at a heating rate of 5 °C / min, and held at this temperature for 2 h, maintaining a constant temperature of 80 cm throughout the heating process. 3 An argon flow atmosphere of / min was maintained. After heating, the mixture was allowed to cool naturally to room temperature to obtain non-carbon point anchored Ni single-atom catalyst powder.

[0042] Comparative Example 2 300 mg of melamine was weighed and dissolved in 50 mL of deionized water. The solution was ultrasonically dispersed for 30 min, stirred continuously for 2 h, and after uniform dispersion, rapidly frozen using liquid nitrogen. The solution was then placed in a vacuum freeze dryer and continuously freeze-dried at -55 °C and 10 Pa for 30 h to obtain a solid aerogel. The solid aerogel was transferred to a tube furnace and heated to 500 °C at a heating rate of 5 °C / min, and maintained at this temperature for 2 h, while maintaining a constant depth of 80 cm throughout the heating process. 3 An argon flow atmosphere of / min was maintained. After heating, the mixture was allowed to cool naturally to room temperature to obtain Ni-free carbon nitride catalyst powder.

[0043] Comparative Example 3 50 mg of nickel acetylacetone (Ni(C5H7O2)2) and 300 mg of urea were weighed and dissolved in 50 mL of deionized water. The mixture was ultrasonically dispersed for 30 min, stirred continuously for 2 h, and after uniform dispersion, rapidly frozen with liquid nitrogen. The aerogel was then placed in a vacuum freeze dryer and continuously freeze-dried at -55 °C and 10 Pa for 30 h to obtain a solid aerogel. The solid aerogel was transferred to a tube furnace and heated to 600 °C at a heating rate of 5 °C / min, and maintained at this temperature for 2 h, while maintaining a constant height of 60 cm throughout the heating process. 3 A nitrogen flow atmosphere of [amount] / min was applied. After heating, the catalyst powder was obtained after natural cooling to room temperature.

[0044] Application performance testing (a) Determination of cumulative hydrogen peroxide production The cumulative production experiment of hydrogen peroxide was conducted in an H-type two-chamber electrolyzer separated by a proton exchange membrane. The cathode employed a natural air diffusion electrode requiring no additional aeration. The preparation method was as follows: 0.264 g of the Ni single-atom catalyst from the examples was mixed with an equal mass of carbon black, followed by the addition of 176 μL of PTFE emulsion and 5 mL of anhydrous ethanol. After ultrasonic dispersion of the mixture, it was coated onto an area of ​​4 × 5 cm². 2 The anode was sintered on a carbon felt substrate at 360 °C for 1 hour. A commercially available ruthenium-iridium titanium electrode, manufactured by Shaanxi Kaida Chemical Co., Ltd., was used; this electrode is a titanium plate coated with iridium dioxide and also measures 4 × 5 cm. 2 The concentration of hydrogen peroxide was determined by potassium titanium oxalate spectrophotometry at a wavelength of 400 nm.

[0045] Faraday efficiency (FE) is calculated using the following formula:

[0046] In the formula, n is the number of electrons transferred in each H2O2 molecule (for 2e...). - ORR is 2), F is the Faraday constant (96485 C·mol⁻¹). -1 C represents the measured H2O2 concentration (mol·L⁻¹). -1 V is the volume of the electrolyte (L), and M is the molar mass of H2O2 (34.01 g·mol⁻¹). -1 Q is the total charge (C) passing through.

[0047] (II) Measurement of disk current and loop current The disk current and ring current were measured using a standard three-electrode system on a CHI-760 electrochemical workstation. The electrolyte was an oxygen-saturated 0.5 M NaCl solution. The reference and counter electrodes were Ag / AgCl electrodes and platinum sheets, respectively. The working electrode was a rotating ring-disk electrode from PINE Research Instrumentation with a geometric area of ​​0.2475 cm² and a collection efficiency of 0.383. The catalyst ink was prepared by dispersing 5 mg of catalyst in a mixture of 950 μL anhydrous ethanol and 50 μL Nafion solution (Example 1, Comparative Example 1, and Comparative Example 2). Subsequently, 10 μL of this ink was drop-coated onto a glassy carbon substrate and air-dried for subsequent testing. The RRDE rotation speed was set to 1600 rpm. The selectivity for H₂O₂ was... η ) and the number of transferred electrons ( n The current can be calculated from the disk current and the ring current, using the following formula: ; ;

[0048] In the formula, I D and I R These represent disk current and ring current, respectively. N The collection efficiency of the rotating ring disk electrode is 0.383.

[0049] Table 1. Comparison of hydrogen peroxide production performance of each comparative example and embodiment.

[0050] Figure 1 This is a schematic diagram of the preparation process of the carbon dot-anchored Ni single-atom catalyst in Example 1 of the present invention.

[0051] Figure 2 This is a high-angle annular dark-field image of the catalyst in Example 1 of the present invention, taken under a spherical aberration-corrected scanning transmission electron microscope. The highlighted sites in the image indicate that monodisperse Ni is distributed in atomic form on a carbon-nitrogen substrate composed of carbon dots.

[0052] Figure 3 The X-ray absorbing near-edge structure (XANES) of the catalyst prepared in Example 1 of this invention Figure 3 a) and Fourier transform k 3 Weighted extended X-ray absorption fine structure (EXAFS) Figure 3(b) For comparison, Ni foil, nickel oxide (NiO), and Ni phthalocyanine (NiPc) were also tested. The absorption edge of the Ni single-atom catalyst material in Example 1 is located between the Ni foil and NiO, indicating that the valence state of Ni is between 0 and +2, and the Fourier transform k 3 Weighted EXAFS images revealed a main peak at 1.29 Å in the material, which can be attributed to the first shell of Ni-N coordination. However, unlike the Ni foil, no Ni-Ni bond peak was observed at approximately 2.15 Å in this material, indicating that the Ni species exist in a single-atom form.

[0053] Figure 4 Examples 1, 2, and 3 of this invention were prepared in simulated seawater (0.5 mol / L NaCl) at the same current density (30 mA / cm²). 2 The cumulative H2O2 production performance of Example 1 was compared with that of Comparative Example 1 and Comparative Example 2 at the same current density. The H2O2 yield of Example 1 was 2.12 times and 1.36 times that of Comparative Example 1 and Comparative Example 2, respectively, which confirms that the carbon point anchored Ni single-atom catalyst can significantly improve the H2O2 production.

[0054] Figure 5 This invention provides examples of H2O2 yield and Faraday efficiency at different current densities in Example 2. The yields were measured at different applied current densities (10~200 mA / cm²). 2 The cumulative yield of H2O2 was measured at 30 mA / cm². Within a fixed electrolysis time, the cumulative yield of H2O2 increased with increasing current density, reaching a maximum at 30 mA / cm². 2 It achieved its highest Faraday efficiency of 98.29% at a current density of 200 mA / cm². 2 The highest hydrogen peroxide yield of 211.42 mg / h / cm³ was achieved at this current density. 2 .

[0055] Figure 6 The disk current and ring current polarization curves measured on the rotating ring disk electrode in Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention are shown. Figure 6 a) and H2O2 selectivity and electron transfer number ( Figure 6 (b) The material in Example 1 exhibited the highest disk current and ring current response, and correspondingly the highest calculated hydrogen peroxide selectivity of 95.9% and an electron transfer number of 2.03.

[0056] Figure 7 The catalyst prepared in Example 1 of this invention was subjected to a simulated seawater electrolyte at 30 mA / cm². 2Long-term stability test results at current density. Throughout the test period, the decay rate of current density was less than 5%, and the Faraday efficiency remained above 80%, confirming the electrochemical stability of the embodiment and demonstrating good application prospects.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A catalyst for producing hydrogen peroxide from seawater, characterized in that: Carbon dots serve as catalyst supports, with nickel dispersed on the surface of the carbon dots in the form of single atoms, and the nickel single atoms coordinated with the nitrogen atoms of the carbon dots.

2. The catalyst for producing hydrogen peroxide from seawater as described in claim 1, characterized in that: The carbon dot surface contains at least one nitrogen-containing functional group selected from amino, pyridine nitrogen, and graphitic nitrogen; preferably, the carbon dot surface also contains at least one oxygen-containing functional group selected from carbonyl, carboxyl, and hydroxyl.

3. A method for preparing a catalyst for hydrogen peroxide production from seawater as described in claim 1 or 2, characterized in that: Includes the following steps, 1) Dissolve nickel salt and carbon dots in deionized water, mix, and obtain a mixed solution; 2) Add nitrogen-containing organic ligands to the mixture obtained in step 1), disperse by ultrasonication to fully coordinate nickel ions with nitrogen-containing functional groups on the surface of carbon dots, and then freeze-dry to obtain an aerogel precursor. 3) Collect the aerogel precursor from step 2), introduce a protective gas, and pyrolyze it at a specific temperature for a certain time to obtain a nickel single-atom catalyst, which is a catalyst for producing hydrogen peroxide from seawater.

4. The method for preparing the catalyst for hydrogen peroxide production from seawater as described in claim 3, characterized in that: In step 1), the nickel salt is one or more of nickel acetate tetrahydrate, nickel chloride, and nickel acetylacetone; the nitrogen-containing organic ligand is one or more of bisacrylamide, melamine, and urea; in step 1), the mass ratio of the nickel salt, carbon dots, and nitrogen-containing organic ligand is 1:(1~5):(10~30), and the content of the nickel salt in deionized water is 0.1~2 mg / mL.

5. The method for preparing the catalyst for producing hydrogen peroxide from seawater as described in claim 3, characterized in that: In step 1), the mixing is ultrasonic dispersion mixing, with an ultrasonic dispersion frequency of 30~50kHz and a time of 10~120min; in step 2), the ultrasonic dispersion frequency is 30~50kHz and the time is 10~120min; the freeze drying temperature is -45~-55 ℃, the pressure is 1~20 Pa, and the time is 12~36h.

6. The method for preparing the catalyst for producing hydrogen peroxide from seawater as described in claim 3, characterized in that: In step 3), the protective gas is argon or nitrogen, and the gas flow rate is 20~100 cm. 3 The heating rate is 2-5 °C / min, the pyrolysis temperature is 300-700 °C, the heating rate is 2-5 °C / min, and the heating time is 1-3 h.

7. The method for preparing the catalyst for hydrogen peroxide production from seawater as described in claim 3, characterized in that: The method for preparing carbon dots in step 1), Includes the following steps, Citric acid and urea are dissolved in ethylene glycol, stirred, heated, filtered, and dialyzed using deionized water as the external dialysis solution. The dialysate is then freeze-dried to obtain carbon dot powder. The molar ratio of citric acid, urea, and ethylene glycol is 1:(1~3):(40~80). The heating temperature is 120~240℃, and the heating time is 2~24h. The diameter of the filter membrane used for filtration is 0.1~0.5 μm, and the volume of deionized water used for dialysis is 800~1500mL. The dialysis time is 2~72h. The external dialysis solution is changed 2~4 times every 24h, and the freeze-drying time is 12~48h.

8. The application of the catalyst for producing hydrogen peroxide from seawater as described in claim 1 or 2, or the catalyst prepared by the preparation method according to any one of claims 3 to 7, in the electrocatalytic production of hydrogen peroxide.

9. The application as described in claim 8, characterized in that: The electrolyte for electrocatalysis is seawater, simulated seawater, or alkaline sodium chloride solution.

10. The application as described in claim 8, characterized in that: The operating current density for electrocatalytic hydrogen peroxide production is 10~200 mA / cm². 2 .

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