Preparation method of high-spin state cobalt monatomic catalyst and application thereof in neutral electro-synthesis of hydrogen peroxide

Abstract

The application provides a preparation method of a high-spin-state cobalt monatomic catalyst and application of the high-spin-state cobalt monatomic catalyst in neutral electro-synthesis of hydrogen peroxide, and belongs to the technical field of electro-catalytic synthesis. A conductive carbon material dispersion liquid is mixed with a binuclear sulfonated cobalt phthalocyanine dispersion liquid, an adsorption reaction is carried out under magnetic stirring, and the obtained mixed liquid is subjected to suction filtration, washing and drying to obtain the high-spin-state cobalt monatomic catalyst, which has the advantages of simple steps and high repeatability. In the application, the binuclear sulfonated cobalt phthalocyanine is loaded on the conductive carbon material to realize construction of a high-spin-state cobalt center, so as to promote activation of O2 and improve reaction kinetics, and the application has excellent catalytic activity, hydrogen peroxide selectivity and stability in the neutral electro-synthesis of hydrogen peroxide. The application can also be used for synthesizing pure hydrogen peroxide solution with a concentration reaching the medical-grade disinfectant water standard, and the voltage of a reaction cell is lower than 2.2 V, so the application has great application potential of low energy consumption and direct synthesis.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic synthesis technology, specifically relating to a method for preparing a high-spin-state cobalt single-atom catalyst and its application in the neutral electrosynthesis of hydrogen peroxide. Background Technology

[0002] Hydrogen peroxide, with its dual advantages of being both environmentally friendly and having strong oxidizing properties, is experiencing continuously growing demand in fields such as green bleaching, chemical synthesis, and wastewater treatment. However, current hydrogen peroxide synthesis primarily relies on the anthraquinone process, which is not only energy-intensive and highly polluting, but its centralized production model also leads to high storage and transportation costs and explosion risks for subsequent use. In contrast, the electrocatalytic two-electron oxygen reduction method can directly utilize renewable energy, air, and water as material and energy sources for hydrogen peroxide synthesis, making it more environmentally friendly. Furthermore, it holds promise for building distributed production systems, enabling on-site, on-demand production and even in-situ utilization of hydrogen peroxide. Therefore, electrocatalytic synthesis is a highly promising route for achieving green, distributed, low-cost, and safe production of hydrogen peroxide.

[0003] Currently, catalyst development for the electrocatalytic synthesis of hydrogen peroxide mainly focuses on alkaline and acidic electrolyte systems. Research on neutral electrolytes is limited due to difficulties in water dissociation and the formation of oxygen-containing intermediates, as well as high reaction overpotentials. Nevertheless, the electrosynthesis of hydrogen peroxide in neutral or near-neutral systems still possesses unique advantages. First, compared to strong acid and strong base systems, the mild pH of neutral systems reduces corrosion of electrochemical equipment, and the products exhibit better environmental friendliness and safety, making them promising for disinfection and sterilization in agriculture, animal husbandry, and public health. Simultaneously, the neutral environment helps inhibit the decomposition of hydrogen peroxide, improving product stability. Furthermore, the development of highly efficient neutral catalysts allows for the direct production of hydrogen peroxide from neutral pure water, or the use of near-neutral polluted natural water bodies (such as river water and seawater) as reaction media. This enables in-situ purification and disinfection of water bodies while synthesizing hydrogen peroxide, providing a green and continuous treatment solution for addressing eutrophication and microbial contamination.

[0004] Theoretical calculations have shown that cobalt single-atom catalysts hold promise for lowering the energy barrier of two-electron oxygen reduction and enhancing catalytic activity. However, previous studies have largely focused on regulating the type and number of coordinating atoms around cobalt, neglecting the spin state of the cobalt center as a key electronic structure factor influencing the adsorption and activation behavior of the reactant (O2). Furthermore, these regulations are often achieved through pyrolysis, as exemplified by the Chinese patent CN119243212A, which involves complex steps such as ball milling, pyrolysis, and acid washing. The resulting catalysts exhibit insufficiently uniform and well-defined active sites, low reproducibility, and are unfavorable for future large-scale applications. While constructing model catalysts using macrocyclic molecules with cobalt metal centers as precursors is an ideal platform for studying structure-activity relationships, existing research, such as the Chinese patent CN115369427A, still relies on complex functional group modifications of carbon supports and typically uses mononuclear cobalt phthalocyanine, which has limited electronic structure regulation capabilities.

[0005] In particular, recent research (Ding, J. et al. Nature Communications 2023, 14, 6550) indicates that by loading dinuclear cobalt phthalocyanine onto a nitrogen-doped carbon support and then performing high-temperature pyrolysis, the cobalt center can be transformed from a low-spin state to a high-spin state, thereby significantly improving the performance of methanol production from carbon monoxide electroreduction. However, this high-temperature pyrolysis process (~400 °C) not only increases energy consumption and step complexity but may also introduce structural uncertainties and the risk of metal aggregation. How to rationally construct high-spin cobalt centers through molecular engineering under mild conditions without high-temperature pyrolysis and apply them to the more challenging two-electron oxygen reduction to hydrogen peroxide reaction in a neutral medium remains an unresolved technical challenge in this field. Summary of the Invention

[0006] To address the current shortcomings in the development of high-performance electrosynthetic catalysts for hydrogen peroxide in neutral systems, and the problems of existing methods for constructing high-spin-state cobalt centers relying on high-temperature pyrolysis and involving complex steps, this invention provides a method for preparing high-spin-state cobalt single-atom catalysts and their application in the neutral electrosynthesis of hydrogen peroxide. The preparation process can be carried out at room temperature without high-temperature pyrolysis. Through mild and controllable molecular engineering techniques, cobalt single-atom active centers with well-defined structures and high spin states are directly constructed on conductive carbon supports. This overcomes the challenge of slow kinetics in the two-electron oxygen reduction reaction in neutral media, achieving efficient, highly selective, and highly stable electrosynthesis of hydrogen peroxide.

[0007] The technical solution adopted in this invention is as follows:

[0008] The first objective of this invention is to provide a method for preparing a high-spin-state cobalt single-atom catalyst, comprising the following steps:

[0009] Step 1: Disperse the conductive carbon material in an organic solvent to obtain dispersion A;

[0010] Step 2: Disperse the molecular catalyst, binuclear sulfonated cobalt phthalocyanine (BCoPc), in an organic solvent to obtain dispersion B;

[0011] Step 3: Mix dispersion A and dispersion B, and carry out the adsorption reaction by magnetic stirring, so that the binuclear sulfonated cobalt phthalocyanine is anchored to the surface of the conductive carbon material through π-π stacking effect to obtain a mixed solution;

[0012] Step 4: The mixture is filtered, and the resulting solid is washed and dried to obtain a high-spin-state cobalt single-atom catalyst.

[0013] Furthermore, when dispersion A and dispersion B are mixed in step 3, the mass ratio of the dinuclear sulfonated cobalt phthalocyanine to the conductive carbon material is 0.02~0.4:1.

[0014] Further, the conductive carbon material mentioned in step 1 is at least one of carbon black (CB), carbon nanotubes (CNT), graphene, and mesoporous carbon, preferably carbon black.

[0015] Furthermore, the concentration of dispersion A in step 1 is 1~3 mg / mL.

[0016] Furthermore, the concentration of dispersion B in step 2 is 0.1~1 mg / mL.

[0017] Furthermore, the magnetic stirring speed in step 3 is 300~600 rpm, and the adsorption reaction duration is 20~48 h.

[0018] Furthermore, ultrasonic treatment is used for dispersion in steps 1 and 2, and ultrasonic treatment is used for mixing in step 3. The duration of ultrasonic treatment is 0.5 to 3 hours.

[0019] Furthermore, in step 4, organic solvents and alcohol solvents are used for repeated washing.

[0020] Furthermore, the organic solvents used in steps 1, 2, and 4 are the same, specifically any one of N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), or dimethyl sulfoxide (DMSO), preferably DMF.

[0021] Furthermore, the alcohol solvent is anhydrous ethanol or isopropanol.

[0022] Furthermore, the drying in step 4 is carried out under vacuum, at a temperature of 50~70 ℃, for a duration of 4~18 hours.

[0023] The second objective of this invention is to provide a high-spin-state cobalt single-atom catalyst, which is obtained by the above-described preparation method.

[0024] Furthermore, the high-spin-state cobalt single-atom catalyst comprises a conductive carbon material and a binuclear sulfonated cobalt phthalocyanine supported on the conductive carbon material, wherein the cobalt exists in the form of Co. 2+ The effective magnetic moment is 3~4.5 μ. B The cobalt loading is 0.1~1 wt%.

[0025] A third objective of this invention is to provide the application of the aforementioned high-spin-state cobalt single-atom catalyst in the neutral electrosynthesis of hydrogen peroxide.

[0026] A neutral electrolytic cell device for synthesizing hydrogen peroxide is designed based on an H-cell or a flow cell; wherein the catalyst supported on the cathode is the aforementioned high-spin-state cobalt single-atom catalyst, and the cathode electrolyte is a 0.05~2 M neutral phosphate buffer, sodium sulfate solution, potassium sulfate solution, or sodium chloride solution.

[0027] Furthermore, when the neutral electrosynthesis hydrogen peroxide electrolytic cell device is designed based on an H-type electrolytic cell, the anode electrolyte is a 0.05~2 M neutral phosphate buffer, sodium sulfate solution, potassium sulfate solution, or sodium chloride solution; the cathode substrate is a glassy carbon electrode, carbon paper, or carbon cloth, with a catalyst loading of 0.1~0.3 mg / cm²; the anode is a platinum sheet or graphite rod; and the cathode chamber and anode chamber are separated by anion exchange membrane or proton exchange membrane.

[0028] Furthermore, when the neutral electrosynthetic hydrogen peroxide electrolyzer is designed based on a flow electrolyzer, the anolyte is a 0.05-1 M sulfuric acid or perchloric acid solution; the cathode substrate is hydrophobic carbon paper, and its catalyst loading is 0.12-0.25 mg / cm³. 2 The anode is made of hydrophilic carbon paper and supported by IrO2 or RuO2 catalysts. The cathode and anode are separated by a proton exchange membrane.

[0029] A neutral electrosynthetic hydrogen peroxide solution electrolysis device is designed based on a porous solid electrolyte (PSE) reactor; wherein the cathode catalyst is the aforementioned high-spin-state cobalt single-atom catalyst.

[0030] Furthermore, the neutral electrolytic hydrogen peroxide solution electrolysis device comprises a cathode plate with a serpentine flow channel, a cathode catalyst, an anion exchange membrane, a porous solid electrolyte packing plate, a proton exchange membrane, an anode catalyst, and an anode plate with a serpentine flow channel, which are stacked sequentially. Oxygen is introduced into the cathode plate, the cathode substrate is hydrophobic carbon paper, and the catalyst loading on it is 0.12~0.25 mg / cm². The anode catalyst is IrO₂ or RuO₂. The anode electrolyte is a 0.05~1 M sulfuric acid or perchloric acid solution. Deionized water is circulated in the porous solid electrolyte packing plate at a flow rate of 1~5 mL / min.

[0031] The core of this invention lies in the ingenious utilization of the special molecular precursor, dinuclear sulfonated cobalt phthalocyanine. On one hand, the "dual-core" structure of the BCoPc molecule results in conjugation and steric hindrance effects between the two phthalocyanine rings, causing a microscopic distortion of the coordination environment of the single cobalt center, deviating from a perfect planar quadrilateral structure. On the other hand, the "sulfonic acid group" (-SO3H) of the BCoPc molecule, as a strong electron-withdrawing group, further modulates the electron cloud density and crystal field splitting energy of the cobalt center. The synergistic effect of these two factors allows the cobalt center of the BCoPc molecule to spontaneously transition from a low-spin state to a high-spin state without high-temperature pyrolysis when anchored to the surface of a conductive carbon material through a gentle π-π stacking interaction. This high-spin cobalt center possesses a unique d-orbital electron configuration, whose d... z² The orbital energy level shifts upward, and d xz / yz The presence of unpaired electrons in the orbital greatly enhances its interaction with the π electrons of the O2 molecule. * The feedback π-bonding effect of the antibonding orbital significantly promotes the activation of the O2 molecule, accelerates the kinetics of the two-electron oxygen reduction reaction, and ultimately exhibits excellent catalytic activity, selectivity and stability under neutral conditions.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. This invention proposes a novel method for preparing high-spin-state cobalt single-atom catalysts without high-temperature pyrolysis. It has the advantages of simple steps and high reproducibility, which is completely different from traditional pyrolysis methods (such as those described in Ding, J. et al. Nature Communications 2023, 14, 6550) and carbon support functionalization methods (such as those described in CN115369427A). This invention introduces dual structural units of "dual core" and "sulfonic acid group" at the molecular level, and for the first time achieves rational control of the central spin state of cobalt under room temperature adsorption conditions. This avoids the energy consumption and structural uncertainty caused by high-temperature processes, and the preparation method is greener and more controllable.

[0034] 2. This invention reveals the molecular mechanism by which "dino-sulfonic acid groups" synergistically induce the high-spin state of the cobalt center. Using superconducting quantum interference devices (SQUIDs) and other methods, it has been clearly demonstrated that the cobalt in the CB-BCoPc catalyst based on dinuclear sulfonated cobalt phthalocyanine is in a high-spin state, Co²⁺ (effective magnetic moment ~4.2 μm). B In contrast, the mononuclear cobalt phthalocyanine CB-MCoPc catalyst and the binuclear unsulfonated cobalt phthalocyanine CB-DCoPc catalyst exhibited intermediate spin states (effective magnetic moment ~2.7 μ). B and 3.2μ B This clear electronic structure characterization establishes for the first time a direct correlation between the "dual-nuclear sulfonic acid molecular structure" and the "cobalt-centered high-spin state," providing entirely new theoretical guidance for the design of high-performance catalysts.

[0035] 3. This invention clearly establishes the structure-activity relationship between the "high-spin cobalt center" and the "neutral electrosynthesis performance of hydrogen peroxide." Benefiting from the highly efficient activation of O2 molecules by the high-spin cobalt center, the catalysts based on dinuclear sulfonated cobalt phthalocyanine (such as CB-BcoPc and CNT-BCoPc) exhibit significantly superior catalytic performance in neutral media compared to mononuclear cobalt phthalocyanine and dinuclear unsulfonated cobalt phthalocyanine control samples. Rotating ring-disk electrode (RRDE) testing shows that its onset potential in 0.1 M phosphate buffer is 0.75 V vs. reversible hydrogen electrode (RHE), close to the theoretical onset potential of two-electron oxygen reduction, and it maintains over 80% Faradaic efficiency (FE) in the potential range of 0.5 V to 0.65 V vs. RHE. Flow cell testing shows that the high-spin cobalt single-atom catalyst in 0.5 M sodium sulfate electrolyte achieves a bias current density of -400 mA / cm² for hydrogen peroxide at a potential of 0.4 V vs. RHE. 2 The conversion frequency (TOF) can reach 387 s. -1 At -300 mA / cm 2 Even -500 mA / cm 2 Even at high current densities, it can still maintain 80% to 90% FE; and at -300 mA / cm 2 It can operate stably for 100 hours, demonstrating excellent catalytic activity, hydrogen peroxide selectivity and stability.

[0036] 4. The high-spin-state cobalt single-atom catalyst prepared by this invention can also be used to synthesize pure hydrogen peroxide solution with a concentration reaching the medical-grade disinfectant standard (about 3 wt%). The reaction cell voltage is less than 2.2 V, which has great application potential for low energy consumption and direct synthesis. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 The X-ray diffraction (XRD) comparison diagrams of CB-BCoPc obtained in Example 1, CB-MCoPc obtained in Comparative Example 1, and CB-DCoPc obtained in Comparative Example 2 are shown.

[0039] Figure 2 High-resolution transmission electron microscope (HR-TEM) images of CB-BCoPc obtained in Example 1, CB-MCoPc obtained in Comparative Example 1, and CB-DCoPc obtained in Comparative Example 2.

[0040] Figure 3 The UV-Vis spectra of the molecular catalysts used in Example 1, Comparative Example 1, and Comparative Example 2, namely, dinuclear sulfonated cobalt phthalocyanine, mononuclear cobalt phthalocyanine, and dinuclear unsulfonated cobalt phthalocyanine, were measured in DMF solvent.

[0041] Figure 4 The curves show the reciprocal of the molar magnetic susceptibility of CB-BCoPc obtained in Example 1, CB-MCoPc obtained in Comparative Example 1, and CB-DCoPc obtained in Comparative Example 2 as a function of temperature, as measured by SQUID.

[0042] Figure 5 The data show the oxygen reduction performance of CB-BCoPc obtained in Example 1, CB-MCoPc obtained in Comparative Example 1, and CB-DCoPc obtained in Comparative Example 2 in the RRDE device under 0.1 M phosphate buffer solution; where (a) is the oxygen reduction polarization curve and hydrogen peroxide oxidation current; (b) is the FE of hydrogen peroxide.

[0043] Figure 6 The data show the hydrogen peroxide synthesis performance of CB-BCoPc obtained in Example 1, CB-MCoPc obtained in Comparative Example 1, and CB-DCoPc obtained in Comparative Example 2 in a flow cell with 0.5 M sodium sulfate electrolyte; where (a) is the polarization curve of hydrogen peroxide as a function of potential; (b) is the hydrogen peroxide FE at different current densities; (c) is the TOF at different potentials; and (d) is the stability test results.

[0044] Figure 7The data show the hydrogen peroxide synthesis performance of CNT-BCoPc obtained in Example 2, CNT-MCoPc obtained in Comparative Example 3, and CNT-DCoPc obtained in Comparative Example 4 in a flow cell with 0.5 M sodium sulfate electrolyte; where (a) is the polarization curve of hydrogen peroxide as a function of potential; (b) is the hydrogen peroxide FE at different current densities; (c) is the TOF at different potentials; and (d) is the stability test results.

[0045] Figure 8 This is a schematic diagram of the PSE reactor used in this invention;

[0046] Figure 9 The data show the hydrogen peroxide synthesis performance of CB-BCoPc obtained in Example 1 in the PSE reactor; where (a) is the curve of PSE reactor voltage change over time; and (b) is the curve of hydrogen peroxide FE, hydrogen peroxide mass fraction and concentration change over time. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0048] Example 1

[0049] In this embodiment, a high-spin-state cobalt single-atom catalyst was prepared by loading a binuclear sulfonated cobalt phthalocyanine onto a CB substrate, denoted as CB-BCoPc. The cobalt loading was determined to be 0.207 wt% by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0050] The synthesis method of this catalyst specifically includes the following steps:

[0051] Step 1: Weigh 300 mg of CB (model XC72) powder and place it in 120 mL of DMF solution. Sonicate for 30 min to disperse the CB evenly in the DMF solution to obtain dispersion A.

[0052] Step 2: Weigh 28 mg of dinuclear sulfonated cobalt phthalocyanine powder and place it in 120 mL of DMF solution. Sonicate for 1 h to disperse the dinuclear sulfonated cobalt phthalocyanine powder evenly, to obtain dispersion B.

[0053] Step 3: Pour dispersion B into dispersion A, mix, and continue ultrasonic treatment for 1 h. Then stir at 500 rpm on a magnetic stirrer for 24 h to anchor the binuclear sulfonated cobalt phthalocyanine to the CB surface through π-π stacking to obtain a mixture.

[0054] Step 4: Filter the obtained mixture using an organic filter membrane to obtain a solid product, and wash the solid product several times with DMF solution and anhydrous ethanol alternately until the filtrate is colorless;

[0055] Step 5: Transfer the washed solid product to a vacuum drying oven at 60 °C and dry for 6 h to obtain the high-spin state cobalt single-atom catalyst CB-BCoPc.

[0056] Comparative Example 1

[0057] In this comparative example, a medium-spin-state cobalt single-atom catalyst was prepared by supporting mononuclear cobalt phthalocyanine (MCoPc) on CB, denoted as CB-MCoPc. Its cobalt loading was determined to be 0.22 wt% by ICP-OES, and its effective magnetic moment was determined to be 2.7 μm by SQUID. B .

[0058] The synthesis method of this catalyst differs from that of Example 1 only in that step 2, "weighing 28 mg of dinuclear sulfonated cobalt phthalocyanine powder and placing it in 120 mL of DMF solution", is changed to "weighing 11 mg of mononuclear cobalt phthalocyanine powder and placing it in 60 mL of DMF solution". The remaining steps are the same.

[0059] Comparative Example 2

[0060] Another medium-spin-state cobalt single-atom catalyst was prepared in this comparative example by loading binuclear unsulfonated cobalt phthalocyanine (DCoPc) onto CB, denoted as CB-DCoPc, and its cobalt loading was determined to be 0.35 wt% by ICP-OES.

[0061] The synthesis method of this catalyst differs from that of Example 1 only in that step 2, "weighing 28 mg of dinuclear sulfonated cobalt phthalocyanine powder and placing it in 120 mL of DMF solution," is changed to "weighing 20 mg of dinuclear unsulfonated cobalt phthalocyanine powder and placing it in 120 mL of DMF solution." The remaining steps are the same.

[0062] The CB-BCoPc obtained in Example 1, CB-MCoPc obtained in Comparative Example 1, and CB-DCoPc obtained in Comparative Example 2 are then tested and characterized:

[0063] (1) According to Figure 1The XRD comparison diagrams shown indicate that all three exhibit broad diffraction peaks for the carbon support only at approximately 25° and 43°, with no crystalline phase peaks of the metal or its oxide detected, suggesting that the metal elements may be atomically dispersed.

[0064] (2) Figure 2 The HRTEM images show that all three images only reveal the typical onion-shaped graphite striations of the CB carrier, without any metal nanoparticles, confirming that cobalt is atomically dispersed.

[0065] (3) According to Figure 3 The UV-vis results shown all three exhibit significant absorption peaks in the 650–700 nm range, corresponding to the Q band of phthalocyanine. The figure reveals a significant redshift in the Q band of binuclear sulfonated cobalt phthalocyanine compared to mononuclear cobalt phthalocyanine and binuclear unsulfonated cobalt phthalocyanine. This suggests a lower splitting energy of the Co 3d orbitals in its crystal field, making it easier to induce high-spin metal centers.

[0066] (4) The curves of the reciprocal of the molar magnetic susceptibility of the three as a function of temperature were measured by SQUID, as shown in the figure. Figure 4 As shown, the equivalent magnetic moment μ of CB-MCoPc, CB-DCoPc, and CB-BCoPc was calculated. eff 2.7 μ B 3.2 μ B and 4.2 μ B This proves that Co in CB-BCoPc 2+ It possesses a higher spin state; CB-MCoPc, without the synergistic effect of "dual nuclei" and "sulfonic acid groups," cannot construct a high-spin cobalt center simply by loading a mononuclear cobalt phthalocyanine. 2+ It exhibits an intermediate spin state; however, in CB-DCoPc, although the effective magnetic moment is improved compared to the mononuclear structure due to the distortion of the coordination environment of the cobalt center in the "dual-core" structure, a high-spin cobalt center cannot be successfully constructed simply by loading a dual-core cobalt phthalocyanine without the assistance of the "sulfonic acid group". 2+ It exhibits an intermediate spin state.

[0067] The two-electron oxygen reduction performance of CB-BCoPc obtained in Example 1, CB-MCoPc obtained in Comparative Example 1, and CB-DCoPc obtained in Comparative Example 2 are tested below.

[0068] Specifically, the two-electron oxygen reduction performance was evaluated using an RRDE device in 0.1 M phosphate buffer, and the results are as follows: Figure 5 As shown. Among them, Figure 5(a) shows the oxygen reduction polarization curve and the hydrogen peroxide oxidation current. It can be seen that the onset potential of CB-BCoPc is 0.75 V vs. RHE, which is close to the theoretical onset potential of two-electron oxygen reduction. It is nearly 150 mV higher than the onset potential of CB-MCoPc and CB-DCoPc, and is in a leading position compared with the neutral catalysts reported in previous studies, indicating that it has excellent intrinsic activity. Figure 5 (b) is hydrogen peroxide FE. CB-BCoPc can maintain more than 80% of FE in the potential range of 0.5 V ~ 0.65 V vs. RHE.

[0069] Example 2

[0070] This embodiment prepared a high-spin-state cobalt single-atom catalyst by supporting binuclear sulfonated cobalt phthalocyanine on CNTs, denoted as CNT-BCoPc. The preparation process is the same as in Example 1, except that the CB powder in step 1 is replaced with CNT powder (30-50 nm in size). The remaining steps are the same.

[0071] Comparative Example 3

[0072] This comparative example prepared a medium-spin-state cobalt single-atom catalyst, obtained by loading mononuclear cobalt phthalocyanine onto CNTs, denoted as CNT-MCoPc. The preparation process differed from Example 2 only in that step 2, "weighing 28 mg of dinuclear sulfonated cobalt phthalocyanine powder and placing it in 120 mL of DMF solution," was changed to "weighing 11 mg of mononuclear cobalt phthalocyanine powder and placing it in 60 mL of DMF solution." The remaining steps were the same.

[0073] Comparative Example 4

[0074] This comparative example prepared another medium-spin-state cobalt single-atom catalyst, denoted as CNT-DCoPc, by supporting binuclear unsulfonated cobalt phthalocyanine powder on CNTs. The synthesis method differed from Example 2 only in that step 2, "weighing 28 mg of binuclear unsulfonated cobalt phthalocyanine powder and placing it in 120 mL of DMF solution," was changed to "weighing 20 mg of binuclear unsulfonated cobalt phthalocyanine powder and placing it in 120 mL of DMF solution." The remaining steps were the same.

[0075] Example 3

[0076] This embodiment proposes a neutral electrosynthesis hydrogen peroxide electrolyzer device based on a flow cell design.

[0077] Specifically, the CB-BCoPc obtained in Example 1 or the CNT-BCoPc obtained in Example 2 was loaded onto hydrophobic carbon paper as a cathode (working area 0.6 cm²). 2 Loading capacity 0.15 mg / cm³2 The cathode electrolyte was 0.5 M sodium sulfate, and the corresponding peristaltic pump flow rate was set to 2 mL / min; the anode used hydrophilic carbon paper loaded with IrO2 (working area 0.6 cm²). 2 Loading capacity 2 mg / cm 2 The anolyte was 0.5 M sulfuric acid, and the corresponding peristaltic pump flow rate was set to 30 mL / min. The cathode and anolyte chambers were separated by a proton exchange membrane. The reference electrode was a saturated calomel electrode (SCE), and the oxygen flow rate was set to 30 sccm.

[0078] Comparative Example 5

[0079] This comparative example presents a neutral electrosynthesis hydrogen peroxide electrolyzer device based on a flow cell design. The structure differs from Example 3 only in that the cathode-supported catalyst is changed to one of the catalysts obtained in Comparative Examples 1-4. The rest of the structure remains the same.

[0080] The hydrogen peroxide synthesis performance of the neutral electrolytic cell apparatus for hydrogen peroxide synthesis in Example 3 and Comparative Example 5 is tested below.

[0081] (1) The hydrogen peroxide synthesis performance data of CB-BCoPc obtained in Example 1, CB-MCoPc obtained in Comparative Example 1, and CB-DCoPc obtained in Comparative Example 2 under high current density are as follows: Figure 6 As shown, where Figure 6 (a) shows the polarization curve of hydrogen peroxide's bias current density as a function of potential. CB-BCoPc exhibits the smallest overpotential at the same current density, and the bias current density of hydrogen peroxide can reach -400 mA / cm² at a potential of 0.4 V vs. RHE. 2 Compared with CB-MCoPc and CB-DCoPc, it can save about 100 mV of overpotential; Figure 6 (b) shows hydrogen peroxide FE at different current densities, which can be seen at -300 mA / cm². 2 Even -500mA / cm 2 Even at high current densities, CB-BCoPc can still maintain 80% to 90% FE, which is crucial for actual production. Figure 6 (c) represents the TOF at different potentials. It can be seen that at the same potential, the Co site of CB-BCoPc has significantly higher reactivity than CB-MCoPc and CB-DCoPc, with a TOF of 387 s at 0.4 V vs. RHE. -1 This is far higher than the 41 s of CB-MCoPc. -1 And CB-DCoPc's 75 s -1 ; Figure 6(d) shows the stability test results of CB-BCoPc. CB-BCoPc can operate at -300 mA / cm². 2 It can operate stably for 100 hours with FE maintained above 70%.

[0082] (2) The hydrogen peroxide synthesis performance data of CNT-BCoPc obtained in Example 2, CNT-MCoPc obtained in Comparative Example 3, and CNT-DCoPc obtained in Comparative Example 4 under high current density are as follows: Figure 7 As shown, where Figure 7 (a) shows the polarization curve of hydrogen peroxide bias current density as a function of potential. It can be seen that CNT-BCoPc has the smallest overpotential at the same current density, and the bias current density of H2O2 can reach -400 mA / cm² at a potential of 0.39 V vs. RHE. 2 Compared with CNT-MCoPc and CNT-DCoPc, it can save about 100 mV of overpotential; Figure 7 (b) shows hydrogen peroxide FE at different current densities, which can be seen at -300 mA / cm². 2 Even -500 mA / cm 2 At high current densities, CNT-BCoPc can still maintain 85% to 90% FE.

[0083] Example 4

[0084] This embodiment proposes a neutral electrosynthesis hydrogen peroxide solution electrolysis device based on a PSE reactor design.

[0085] Specifically, the structure of the neutral electrosynthesis hydrogen peroxide solution electrolysis device is as follows: Figure 8 As shown, the device includes a cathode plate with a serpentine flow channel, a cathode catalyst, an anion exchange membrane, a porous solid electrolyte packing plate, a proton exchange membrane, an anode catalyst, and an anode plate with a serpentine flow channel, all stacked sequentially. The porous solid electrolyte packing plate circulates 40 mL of deionized water at a flow rate of 3 mL / min and has a hydrogen peroxide mixture outlet. The anode catalyst is IrO2, supported on hydrophilic carbon paper (working area 4 cm²). 2 Loading capacity 2 mg / cm 2 The anolyte was 0.5 M sulfuric acid, with a flow rate of 30 mL / min; the cathode catalyst was CB-BCoPc obtained in Example 1, loaded onto hydrophobic carbon paper (working area 4 cm²). 2 Loading capacity 0.15 mg / cm³ 2 Oxygen is supplied to the cathode plate at a flow rate of 30 sccm.

[0086] The following section presents performance tests of a neutral electrolytic hydrogen peroxide solution electrolysis device for hydrogen peroxide synthesis. The hydrogen peroxide synthesis performance data is as follows: Figure 9 As shown, where, Figure 9 (a) shows the change of reactor voltage over time. As the reaction time increases, the concentration of H2O2 gradually increases. When the reaction is about 17 hours old, the concentration reaches 37,000 ppm (about 3.7 wt%), which meets the concentration standard for medical hydrogen peroxide. Figure 9 (b) shows the changes in FE, hydrogen peroxide mass fraction, and concentration over time. Although some hydrogen peroxide undergoes secondary reduction during the cycle at high concentrations, leading to a decrease in FE, it remains between 65% and 85% throughout the process, demonstrating good reaction sustainability. Furthermore, the reactor voltage remains below 2.2 V throughout the synthesis process, indicating that the device has advantages in energy consumption and holds promise for providing a feasible route for the future green and low-energy synthesis of pure hydrogen peroxide products.

[0087] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high-spin-state cobalt single-atom catalyst, characterized in that, Includes the following steps: Step 1: Disperse the conductive carbon material in an organic solvent to obtain dispersion A; Step 2: Disperse the dinuclear sulfonated cobalt phthalocyanine in an organic solvent to obtain dispersion B; Step 3: Mix dispersion A and dispersion B, and carry out the adsorption reaction by magnetic stirring, so that the binuclear sulfonated cobalt phthalocyanine is anchored to the surface of the conductive carbon material through π-π stacking effect to obtain a mixed solution; Step 4: The mixture is filtered, and the resulting solid is washed and dried to obtain a high-spin-state cobalt single-atom catalyst.

2. The method for preparing the high-spin-state cobalt single-atom catalyst according to claim 1, characterized in that, When dispersion A and dispersion B are mixed in step 3, the mass ratio of the dinuclear sulfonated cobalt phthalocyanine to the conductive carbon material is 0.02~0.4:

1.

3. The method for preparing the high-spin-state cobalt single-atom catalyst according to claim 1, characterized in that, The conductive carbon material mentioned in step 1 is at least one of carbon black, carbon nanotubes, graphene, and mesoporous carbon, and the concentration of dispersion A is 1~3 mg / mL.

4. The method for preparing the high-spin-state cobalt single-atom catalyst according to claim 1, characterized in that, The concentration of dispersion B in step 2 is 0.1~1 mg / mL.

5. The method for preparing the high-spin-state cobalt single-atom catalyst according to claim 1, characterized in that, The magnetic stirring speed in step 3 is 300~600 rpm, and the adsorption reaction time is 20~48 h.

6. A high-spin-state cobalt single-atom catalyst, characterized in that, The effective magnetic moment is obtained by the preparation method according to any one of claims 1 to 5, and the magnetic moment is 3 to 4.5 μ. B .

7. The application of the high-spin-state cobalt single-atom catalyst obtained by the preparation method according to any one of claims 1 to 5 in the neutral electrosynthesis of hydrogen peroxide.

8. A neutral electrolytic hydrogen peroxide electrolysis cell apparatus, characterized in that, The design is based on an H-type electrolytic cell or a flow electrolytic cell; wherein the catalyst supported on the cathode is a high-spin-state cobalt single-atom catalyst obtained by the preparation method described in any one of claims 1 to 5, and the cathode electrolyte is a 0.05 to 2 M neutral phosphate buffer, sodium sulfate solution, potassium sulfate solution or sodium chloride solution.

9. A neutral electrosynthetic hydrogen peroxide solution electrolysis device, characterized in that, Based on the design of a porous solid electrolyte reactor; wherein the cathode catalyst is a high-spin-state cobalt single-atom catalyst obtained by the preparation method described in any one of claims 1 to 5.

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