3D electro-catalysis in-situ hydrogen peroxide generation system and application thereof

Abstract

The application belongs to the technical field of electrocatalytic hydrogen peroxide production, and particularly relates to a 3D electrocatalytic in-situ hydrogen peroxide generation system and application thereof. The 3D electrocatalytic in-situ hydrogen peroxide generation system comprises a cathode, an anode, an electrolyte and a Co@TriBpy-COF catalyst. The Co@TriBpy-COF catalyst is prepared by the following steps: firstly, synthesizing TriBpy-COF triazine covalent organic framework by a solvothermal method, and then anchoring metal Co by pyridine N to obtain the triazine covalent organic framework anchoring metal Co, i.e. the Co@TriBpy-COF catalyst. The 3D electrocatalytic in-situ hydrogen peroxide generation system promotes the catalytic cycle of Co 2+ → Co 3+ → Co 2+ , greatly improves the hydrogen peroxide yield, so that the catalyst can be reused and the stability of the system is improved.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic hydrogen peroxide production technology, specifically relating to a 3D electrocatalytic in-situ hydrogen peroxide production system and its application. Background Technology

[0002] Hydrogen peroxide (H₂O₂) is a versatile and environmentally friendly oxidant that plays a crucial role in a wide range of applications, including environmental protection, healthcare, and organic synthesis. The currently dominant energy-intensive anthraquinone process for H₂O₂ production presents safety and environmental challenges. Therefore, significant efforts have been made to find alternative methods to address the problems associated with the anthraquinone process. In recent years, the electrochemical synthesis of H₂O₂ via the 2-electron oxygen reduction reaction (ORR) has attracted considerable attention and is considered an environmentally friendly, safe, and energy-efficient method. However, the 2-electron ORR faces competition from the 4-electron ORR process, necessitating highly efficient electrocatalysts to achieve the selective conversion of O₂ to H₂O₂.

[0003] To date, various photocatalysts and electrocatalysts, including noble metals, non-metallic materials, transition metal single-site catalysts, metal complexes, and metal oxides, have been developed to selectively accelerate the 2-electron ORR (oxygen reduction reaction). Among these, covalent organic frameworks (COFs) have attracted attention in recent years. COFs are novel crystalline porous materials constructed from organic building blocks through covalent bonds. Due to their pre-designable structural flexibility and ease of post-modification, they are widely used in gas adsorption and separation, sensing, catalysis, and energy storage. In particular, integrating metal active sites into the COF framework has yielded a series of functional COFs, which hold promise for catalyzing various reactions, including the ORR reaction.

[0004] Chinese patent application No. 202310679301.0 discloses a method for preparing a Co single-atom catalyst and its application in the electrocatalytic oxygen reduction to produce hydrogen peroxide. The method involves impregnating cobalt nitrate, zinc nitrate, and 2-methylimidazole in methanol, followed by washing to obtain a precursor (metal-organic framework). The precursor is then carbonized at high temperature to obtain a metallic Co single-atom catalyst. However, when this catalyst is used for the electrochemical oxygen reduction to produce hydrogen peroxide, it requires oxygen saturation conditions for electrocatalytic hydrogen peroxide production, resulting in significant energy consumption from oxygen aeration. Furthermore, sulfuric acid is needed to adjust the initial pH of the medium solution to 2, leading to cumbersome preconditions and high energy consumption. Summary of the Invention

[0005] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a 3D electrocatalytic in-situ hydrogen peroxide generation system.

[0006] Another object of the present invention is to provide an application of the above-mentioned 3D electrocatalytic in-situ hydrogen peroxide generation system.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A 3D electrocatalytic in-situ hydrogen peroxide generation system includes a cathode, an anode, an electrolyte, and a Co@TriBpy-COF catalyst. The Co@TriBpy-COF catalyst is prepared by the following steps: firstly, a TriBpy-COF triazine covalent organic framework is synthesized by a solvothermal method, and then Co is anchored by pyridine N to obtain a Co-anchored triazine covalent organic framework, i.e., the Co@TriBpy-COF catalyst.

[0009] Furthermore, by mass percentage, the Co@TriBpy-COF catalyst contains 90.5% to 91.5% TriBpy-COF and 8.5% to 9.5% Co.

[0010] Furthermore, the Co@TriBpy-COF catalyst is prepared by the following steps:

[0011] S1. 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tri[benzaldehyde] (TATB), 5,5'-diamino-2,2'-bipyridine (BDA) and an organic solvent were mixed and reacted at 110~120 °C for 12~24 h under an inert atmosphere. The mixture was then cooled to obtain a mixture, which was washed and dried to obtain the triazine covalent organic framework TriBpy-COF.

[0012] S2. The triazine covalent organic framework TriBpy-COF obtained in S1 was placed in a solution of cobalt salt and reacted at 50-60 °C for 6-12 h under an inert atmosphere. After the reaction was completed, the product was filtered and washed until the filtrate was colorless and dried to obtain the Co@TriBpy-COF catalyst.

[0013] More preferably, the mass ratio of 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris[benzaldehyde] and 5,5'-diamino-2,2'-bipyridine in step S1 is 1:1. The organic solvent is dimethyl sulfoxide (DMSO). The amount of dimethyl sulfoxide used as a solvent is not strictly limited.

[0014] More preferably, the drying in steps S1 and S2 refers to drying at 50~60 °C for 8~16 hours.

[0015] More preferably, the cobalt salt in step S2 is CoCl2∙6H2O; the mass ratio of the cobalt salt to TriBpy-COF is 1:5.

[0016] Furthermore, the anode is a carbon felt electrode, and the cathode is a titanium plate.

[0017] More preferably, the carbon felt electrode has a diameter of 2 cm and a thickness of 1-2 mm. The anode and cathode are the same size.

[0018] Furthermore, the electrolyte is a 50-100 mmol / L Na2SO4 solution.

[0019] The 3D electrocatalytic in-situ hydrogen peroxide generation system described in this invention can be used to prepare hydrogen peroxide.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] 1. Using a covalent organic framework anchored to metal atoms as a catalyst, the Co-N2 site of the catalyst Co@TriBpy-COF can effectively (i) capture oxygen and water molecules, and (ii) promote the formation of H2O2 by constructing a dynamic coordination structure of Co-N2-O2.

[0022] 2. In the 3D electrocatalytic in-situ hydrogen peroxide generation system, the introduction of an electric field promotes the oxidation of Co... 2+ → Co 3+ → Co 2+ The catalytic cycle allows for catalyst reuse and improves system stability. Attached Figure Description

[0023] Figure 1 These are electron microscope (EM) images of TriBpy-COF and Co@TriBpy-COF prepared in Example 1, where a is an SEM image of TriBpy-COF, b is an SEM image of Co@TriBpy-COF, c is a TEM image of TriBpy-COF, d is a TEM image of Co@TriBpy-COF, and e is an EDS image of Co@TriBpy-COF under TEM.

[0024] Figure 2 The images show the XRD patterns (a), FTIR patterns (b), Roman patterns (c), and XPS patterns (df) of TriBpy-COF and Co@TriBpy-COF prepared in Example 1.

[0025] Figure 3 The LSV spectrum (a) and Tafel spectrum (b) of TriBpy-COF and Co@TriBpy-COF prepared in Example 1 are shown.

[0026] Figure 4 This is a schematic diagram of the 3D electrocatalytic in-situ hydrogen peroxide generation system constructed in Example 2 of the present invention.

[0027] Figure 5This is a comparison diagram of 3D electrocatalytic in-situ hydrogen peroxide generation systems constructed with different metal-supported covalent organic frameworks. COF, Co@COF, Cu@COF and Ni@COF represent TriBpy-COF, Co@TriBpy-COF, Cu@TriBpy-COF and Ni@TriBpy-COF catalysts, respectively.

[0028] Figure 6 These are comparison figures of 3D electrocatalytic in-situ hydrogen peroxide generation systems under different experimental conditions. Figure a shows the rate of H2O2 production by TriBpy-COF under different current densities and rotation speeds, figure b shows the rate of H2O2 production by Co@TriBpy-COF under different current densities and rotation speeds, figure c is the color contour plot corresponding to figure a, and figure d is the color contour plot corresponding to figure b. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. All raw materials involved in the present invention can be purchased directly from the market. For process parameters not specifically specified, conventional techniques can be referred to.

[0030] Example 1: This example demonstrates the preparation of the catalyst Co@TriBpy-COF via a solvothermal method.

[0031] First, 78.7 mg of TATB and 74.5 mg of BDA were added to a 100 mL three-necked flask and mixed. Then, 20 mL of DMSO was added to the solution, followed by sonication for 3 minutes and purging with inert gas N2 / Ar. The reaction was carried out at 115 °C for 72 hours. After cooling to room temperature, the mixture was filtered and washed repeatedly with anhydrous dimethylformamide and ethanol to remove the raw materials. The final sample was placed in a vacuum drying oven and dried at 60 °C for 12 hours to obtain the triazine covalent organic framework TriBpy-COF.

[0032] Then, the triazine covalent organic framework TriBpy-COF obtained from the reaction was placed in 50 mL of ethanol solution containing 20 mg CoCl2∙6H2O, and then an inert gas N2 / Ar was introduced for the reaction. The reaction temperature was set at 50 ℃ and the reaction time was set at 8 h. After the reaction was completed, a covalent organic framework anchored to metal atoms was obtained. The solution was then washed with ethanol and H2O in sequence until the filtrate was colorless. Finally, it was dried in a drying oven at 60 ℃ for 24 h to obtain the Co@TriBpy-COF catalyst (Co content 8.50-9.50%).

[0033] The surface structure and morphology of TriBpy-COF and Co@TriBpy-COF prepared in Example 1 were preliminarily characterized by electron microscopy, and the results are as follows: Figure 1As shown in the scanning electron microscope (SEM) images, the microstructure of Co@TriBpy-COF is very similar to that of TriBpy-COF, both exhibiting a spindle-shaped, sheet-like stacked morphology and a rough surface. Figure 1 (ab in the text). Transmission electron microscopy (TEM) images further elucidated the microstructure of the materials, showing that TriBpy-COF and Co@TriBpy-COF have similar morphologies (ab in the text). Figure 1 (cd in the text). Transmission electron microscopy-energy dispersive spectroscopy (TEM-EDS) ( Figure 1 (e) indicates that cobalt is uniformly distributed throughout the support without forming aggregates. In summary, the cobalt species is precisely anchored at the nitrogen coordination sites formed by the bipyridine and triazine units. The well-preserved support morphology and uniform dispersion of cobalt atoms provide the structural basis for the observed high electrocatalytic activity.

[0034] The structural integrity of the covalent organic framework prepared in the above steps and the successful integration of cobalt species within the tribenzopyridine-covalent organic framework (TriBpy-COF) support were comprehensively verified through spectral analysis using multiple techniques. Figure 2 As shown. X-ray diffraction performed in the range of 5-50° 2θ ( Figure 2 a) confirms the retention of the framework structure after cobalt loading. Notably, the continued presence of broad diffraction features at 2θ ≈ 12° and 26° in both materials indicates the retention of the typical low crystallinity, layered structure of the two-dimensional covalent organic framework. Although the peak positions remain unchanged, a systematic broadening of the diffraction peaks was observed in Co@TriBpy-COF. These subtle changes imply the introduction of local lattice strain and a slight disruption of translational symmetry, directly attributable to atomic-level perturbations caused by metal coordination. Crucially, no new reflections attributable to a crystalline cobalt phase (e.g., metallic cobalt, CoO, or Co3O4 nanoparticles) appeared within the measured angular range, providing evidence for atomic dispersion of the cobalt species. Fourier transform infrared spectroscopy (FT-IR) Figure 2 b) further confirms the stability of the framework while revealing characteristic variations indicating Co-N bond formation. Fingerprint region (1600–800 cm⁻¹) -1 Both materials exhibit almost identical characteristics, with key vibrational modes including sharp C=N tensile vibrations of the imine bond (around 1500 cm⁻¹). -1 Aromatic C=C skeletal vibration (approximately 1350 cm⁻¹) -1 ) and the CN tensile vibration of the pyridyl group (approximately 800 cm⁻¹) -1— Maintaining its position and relative intensity. This consistency confirms that the stability of the covalent framework and aromatic system is not compromised during metallization. The strongest evidence appears in the high wavenumber region: at approximately 500 cm⁻¹ -1 A distinct shoulder peak appeared. This spectral change is a direct result of electronic perturbations caused by the coordination between the Co atom and the lone pair of dipyridine N. This coordination transfers electron density, alters bond polarization, and suppresses vibrations associated with free functional groups, thus confirming the successful anchoring of the metal at the molecular level.

[0035] Figure 3 The images show the LSV (a) and Tafel (b) spectra of TriBpy-COF and Co@TriBpy-COF prepared in Example 1. LSV reflects the variation of the OEP (Optical Equivalent Potential) value of the electrode and the direct electron transfer process in the reaction system. A higher OEP value indicates a greater difficulty in the occurrence of electrochemical oxygen precipitation side reactions, thus resulting in higher electrochemical oxidation current efficiency for organic matter. The OEP value of Co@TriBpy-COF (1.77 V) is higher than that of TriBpy-COF (1.71 V), indicating that the introduction of Co results in higher electron transfer activity and a higher •OH generation rate. Based on Tafel curve analysis (… Figure 3 In b), Co@TriBpy-COF exhibits superior oxygen reduction reaction (ORR) kinetics. Compared to TriBpy-COF (slope 2383 mV·dec), it shows superior kinetics in the ORR. -1 Compared to the previous method, the Co-modified Tafel slope was significantly reduced to 1392 mV·dec. -1 The charge transfer rate decreased by 41.5%, indicating a 2.7-fold increase. At the same overpotential, the current density of Co@TriBpy-COF increased even more significantly, which is directly related to the increased •OH flux generated during the electro-Fenton process. This kinetic enhancement stems from the precise control of the ORR pathway by Co.

[0036] Example 2: This example describes the construction of a 3D electrocatalytic in-situ hydrogen peroxide generation system.

[0037] The electrocatalytic hydrogen peroxide production experiment was conducted in a 100 mL electrolysis apparatus, with a regulated DC power supply providing a constant current to the reaction device. A carbon felt electrode was used as the anode, and a Ti plate as the cathode, with a plate spacing of 1 cm. The supporting electrolyte was a 50 mM Na₂SO₄ solution. 5 mg of the Co@TriBpy-COF catalyst prepared in Example 1 was added to the reactor to obtain a 3D electrocatalytic in-situ hydrogen peroxide generation system. A rotor was added, and the rotation speed was adjusted to 100-300 rpm to stir the mixed solution (a solution of electrolyte and catalyst), followed by electrolytic degradation. During the degradation process, 1.5 mL of sample was extracted, filtered through a 0.22 μm polytetrafluoroethylene membrane, and the hydrogen peroxide concentration was determined using a UV spectrophotometer.

[0038] The 3D electrocatalytic in-situ hydrogen peroxide generation system constructed in this embodiment is as follows: Figure 4 As shown.

[0039] Comparative Example 1

[0040] Following the method described in Example 1, the transition metal element Co was replaced with Cu, while other conditions remained unchanged, to prepare the Cu@TriBpy-COF catalyst.

[0041] Comparative Example 2

[0042] Following the method described in Example 1, the transition metal element Co was replaced with Ni, while other conditions remained unchanged, to prepare the Ni@TriBpy-COF catalyst.

[0043] Comparative Example 3

[0044] (1) Perfluorinated nickel phthalocyanine (PcNi), tetrahydroxybenzene (THB), and potassium carbonate were added to a reactor containing N,N-dimethylformamide (DMF) at a mass ratio of 1:4:10, and then kept at 80 °C for 1 day. The resulting mixture was adjusted to acidity with 1 mol / L hydrochloric acid, filtered, and washed with ethanol and acetone to obtain a covalently bonded COF catalyst (denoted as PcNi-THB).

[0045] (2) PcNi-THB and hydroxylamine hydrochloride were placed in a beaker at a mass ratio of 2.2-2.3:1, and 5 mL of ethanol and deionized water were added respectively. Nitrogen fixation was performed by heating at 65 °C for 5 h under air atmosphere to obtain a white powder. The synthesized COF framework PcNi-THB and cobalt acetate (cobalt salt precursor) were dissolved in N,N-dimethylformamide (DMF) at a mass ratio of 5:1, ensuring complete dissolution. The mixture was then transferred to a reactor and subjected to solvothermal treatment at 100 °C for 2 days to promote the formation of Co-N4 coordination bonds. Finally, the Co@PcNi-THB black powder was washed with DMF, ethanol, and acetone, and dried at 60 °C to obtain the Co@PcNi-THB catalyst.

[0046] Example 1: This example screens the catalytic activity of TriBpy-COF catalysts doped with different transition metal elements in an electrochemical system.

[0047] While preparing TriBpy-COF, the inventors randomly selected two transition metal elements, Cu and Ni, and prepared Cu@TriBpy-COF and Ni@TriBpy-COF catalysts (Comparative Example 1 and Comparative Example 2) under the same preparation conditions and doping amounts as Co@TriBpy-COF. The four catalysts (TriBpy-COF, Co@TriBpy-COF, Cu@TriBpy-COF, and Ni@TriBpy-COF) were used to construct 3D electrocatalytic in-situ hydrogen peroxide generation systems according to the method in Example 2. Rotors were added to each system, the rotation speed was adjusted to 200 rpm, and an initial current density of 10 mA·cm⁻¹ was applied. -2 Under conditions where the solution pH was not changed (pH = 6.70), an electrolytic reaction was carried out. 3.0 mL samples were taken at 30 min and 1 h of reaction time, filtered through a 0.22 μm polytetrafluoroethylene membrane, and the concentration of hydrogen peroxide was determined using a UV spectrophotometer. The electrocatalytic production of hydrogen peroxide was conducted in a 100 mL electrolysis apparatus, with a regulated DC power supply providing a constant current to the reaction apparatus. The efficiency graphs for the electrocatalytic production of hydrogen peroxide using four catalysts are shown below. Figure 5 As shown.

[0048] As shown in the figure, the TriBpy-COF framework itself possesses a certain electrocatalytic ability to produce hydrogen peroxide, with an H2O2 yield of 6.6 mg / L within 1 h. However, the hydrogen peroxide yields of Ni@TriBpy-COF, Cu@TriBpy-COF, and Co@TriBpy-COF catalysts after 1 h of reaction were 9.12, 12.48, and 58.96 mg·L, respectively. -1 Superior to 6.6 mg·L⁻¹ of the TriBpy-COF framework-1 Meanwhile, the hydrogen peroxide yield of Co-supported TriBpy-COF was significantly higher than that of Cu and Ni-supported TriBpy-COF catalysts. It can be observed that the electrocatalytic activity of TriBpy-COF is enhanced after being supported with transition metal elements. Furthermore, under the same conditions, Co@TriBpy-COF produces hydrogen peroxide at a rate nine times higher than the TriBpy-COF framework. In contrast, Ni@TriBpy-COF and Cu@TriBpy-COF electrocatalysis cannot significantly increase hydrogen peroxide yield.

[0049] Example 2: This example investigated the effects of different reaction conditions on the 3D electrocatalytic in-situ hydrogen peroxide generation system.

[0050] A) 3D electrocatalytic in-situ hydrogen peroxide generation systems were constructed using catalysts TriBpy-COF and Co@TriBpy-COF, respectively, following Example 2: A carbon felt electrode was used as the anode, a Ti plate as the cathode, with a plate spacing of 1 cm. The supporting electrolyte was a 50 mM Na₂SO₄ solution. 5 mg of catalyst was added to the reactor to obtain the 3D electrocatalytic in-situ hydrogen peroxide generation system. A rotor was added, and the rotation speed was adjusted to 100 rpm. Degradation was then carried out under current densities of 5, 10, and 15 mA, respectively. The electrocatalytic hydrogen peroxide production experiment was conducted in a 100 mL electrolysis device. A regulated DC power supply provided a constant current to the reaction apparatus. During the degradation process, 3.0 mL of sample was extracted, filtered through a 0.22 μm polytetrafluoroethylene membrane, and the hydrogen peroxide concentration was determined using a UV spectrophotometer.

[0051] B) Referring to step A above, adjust the rotation speed to 200 rpm, and keep the other conditions unchanged for the experiment.

[0052] C) Referring to step A above, adjust the rotation speed to 300 rpm, and keep the other conditions unchanged for the experiment.

[0053] Experimental results are as follows Figure 6 As shown in the figure, a represents the rate of H2O2 production by TriBpy-COF under different current densities and rotation speeds, b represents the rate of H2O2 production by Co@TriBpy-COF under different current densities and rotation speeds, c is the color contour plot corresponding to figure a, and d is the color contour plot corresponding to figure b.

[0054] 1. Effect of current density

[0055] The catalytic activity and stability of Co@TriBpy-COF are significantly better than those of the original TriBpy-COF. Figure 6(ab in the image). Under the same rotational speed conditions, the H2O2 yield of TriBpy-COF decreases sharply with increasing current density, while the strong coupling gradient between current density and rotational speed (6.05-7.31 mg / L) is shown in the color contour plot (ab in the image). Figure 6 c) clearly shows poor accessibility of active sites, indicating mass transfer limitations and low utilization of active sites; however, the catalytic activity and stability of Co@TriBpy-COF are significantly better than those of TriBpy-COF.

[0056] 2. Effect of rotational speed

[0057] TriBpy-COF maintained a yield of 70.55 mg / L at 300 rpm, which is 9.65 times higher than TriBpy-COF, and the isopleth plot ( Figure 6 Figure d) shows a uniform yield distribution (32.70–70.60 mg / L), confirming that Co loading effectively optimizes the mass transfer kinetics at the reaction interface and exposes active sites at a high density. In particular, the yield increase of TriBpy-COF was not significant when the rotational speed increased from 100 rpm to 300 rpm (from 6.39 mg / L to 7.31 mg / L), indicating limited intrinsic activity; conversely, Co@TriBpy-COF showed a significant yield increase at the same current (from 40.66 mg / L to 70.55 mg / L, an increase of 73.51%), highlighting the superiority of Co@TriBpy-COF in electrocatalytic hydroxide production. This performance advantage stems from the optimization of the oxygen adsorption-activation pathway by the cobalt center, enabling the synthesis of hydroxides with high efficiency and sustained performance at higher intensities.

[0058] Example 3:

[0059] This embodiment investigates the effects of different covalent organic frameworks and the loading of the co-transition metal Co on the 3D electrocatalytic in-situ hydrogen peroxide generation system:

[0060] A) Hydrogen peroxide generation systems were constructed using the PcNi-THB and TriBpy-COF catalysts prepared in Comparative Example 3, respectively, as described in Example 2: a carbon felt electrode was used as the anode, a Ti plate as the cathode, the electrode spacing was 1 cm, the supporting electrolyte was 10 mM Na2SO4 solution, and the current density was set to 10 mA / cm². 2 Five mg of catalyst were added to the reactor to obtain a 3D electrocatalytic in-situ hydrogen peroxide generation system; a rotor was added, and the rotation speed was adjusted to 200 rpm. The electrocatalytic hydrogen peroxide production experiment was carried out in a 100 mL electrolysis device, with a regulated DC power supply providing a constant current to the reaction device. The experimental results are shown in Table 1:

[0061] Table 1:

[0062]

[0063] As can be seen from Table 1, not all covalent organic frameworks are capable of producing hydrogen peroxide.

[0064] B) Referring to step A, the catalysts were changed to Co@PcNi-THB and Co@TriBpy-COF catalysts, respectively, while keeping other conditions unchanged. Hydrogen peroxide generation systems were constructed and experiments were conducted. The experimental results are shown in Table 2.

[0065] Table 2:

[0066]

[0067] As can be seen from Table 2, not all covalent organic frameworks loaded with transition metal Co have the ability to significantly improve the efficiency of electrocatalytic hydrogen peroxide production.

[0068] Example 4: This example investigated the production of hydrogen peroxide by electrocatalysis under the same experimental conditions (no pH adjustment, no aeration, etc.) using different Co catalysts.

[0069] The corresponding Co single-atom catalyst was prepared according to Example 1 of Chinese Patent Application No. 202310679301.0, and a hydrogen peroxide generation system was constructed according to Example 2 of this invention: a carbon felt electrode was used as the anode, a titanium plate as the cathode, the electrode spacing was 1 cm, the supporting electrolyte was 50 mM Na2SO4 solution, and the current density was set to 10 mA / cm². 2 A 3D electrocatalytic in-situ hydrogen peroxide generation system was obtained by adding 5 mg of Co single-atom catalyst to the reactor; a rotor was added and the rotation speed was adjusted to 200 rpm. The electrocatalytic hydrogen peroxide production experiment was carried out in a 100 mL electrolysis device, with a regulated DC power supply providing a constant current to the reaction device. The experimental results are shown in Table 3:

[0070] Table 3:

[0071]

[0072] As can be seen from Table 3, not all covalent organic frameworks loaded with transition metal Co can achieve good electrocatalytic hydrogen peroxide production efficiency without adjusting the pH value or aerating to reach oxygen saturation.

[0073] Example 5: This example studies Co catalysts with the same transition metal supported by different processes, and compares the amount of in-situ hydrogen peroxide generated by electrocatalysis under the same experimental conditions:

[0074] A Co@TriBpy-COF2 catalyst was prepared according to Example 1 of Chinese Patent Application No. 202010822293.7, and a hydrogen peroxide generation system was constructed according to Example 2 of this invention: a carbon felt electrode was used as the anode, a titanium plate as the cathode, the electrode spacing was 1 cm, the supporting electrolyte was 50 mM Na2SO4 solution, and the current density was set to 10 mA / cm². 2 5 mg of Co@TriBpy-COF2 catalyst was added to the reactor to obtain a 3D electrocatalytic in-situ hydrogen peroxide generation system; a rotor was added, and the rotation speed was adjusted to 200 rpm. The electrocatalytic hydrogen peroxide production experiment was carried out in a 100 mL electrolysis device, with a regulated DC power supply providing a constant current to the reaction device. The experimental results are shown in Table 4:

[0075] Table 4:

[0076]

[0077] As can be seen from Table 4, not all covalent organic frameworks prepared by any process can have good electrocatalytic performance in producing hydrogen peroxide after being loaded with the transition metal Co.

[0078] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A 3D electrocatalytic in-situ hydrogen peroxide generation system, characterized in that, It includes a cathode, an anode, an electrolyte, and a Co@TriBpy-COF catalyst; the Co@TriBpy-COF catalyst is prepared by the following steps: first, TriBpy-COF triazine covalent organic framework is synthesized by a solvothermal method, and then Co is anchored by pyridine N to obtain the Co@TriBpy-COF catalyst.

2. The 3D electrocatalytic in-situ hydrogen peroxide generation system according to claim 1, characterized in that, By mass percentage, the Co@TriBpy-COF catalyst contains 90.5%~91.5% TriBpy-COF and 8.5%~9.5% Co.

3. The 3D electrocatalytic in-situ hydrogen peroxide generation system according to claim 1, characterized in that, The Co@TriBpy-COF catalyst was prepared by the following steps: S1. 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tri[benzaldehyde], 5,5'-diamino-2,2'-bipyridine and an organic solvent were mixed and reacted at 110~120 °C for 12~24 h under an inert atmosphere. The mixture was then cooled to obtain a mixture, which was washed and dried to obtain the triazine covalent organic framework TriBpy-COF. S2. The triazine covalent organic framework TriBpy-COF obtained in S1 was added to a solution of cobalt salt and reacted at 50-60 °C for 6-12 h under an inert atmosphere. After the reaction was completed, the product was filtered and washed until the filtrate was colorless and dried to obtain the Co@TriBpy-COF catalyst.

4. The 3D electrocatalytic in-situ hydrogen peroxide generation system according to claim 3, characterized in that, The mass ratio of 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tri[benzaldehyde] and 5,5'-diamino-2,2'-bipyridine in step S1 is 1:

1.

5. The 3D electrocatalytic in-situ hydrogen peroxide generation system according to claim 3, characterized in that, The drying described in steps S1 and S2 refers to drying at 50~60℃ for 8~16 hours.

6. The 3D electrocatalytic in-situ hydrogen peroxide generation system according to claim 3, characterized in that, The cobalt salt in step S2 is CoCl2∙6H2O; the mass ratio of the cobalt salt to TriBpy-COF is 1:

5.

7. A 3D electrocatalytic in-situ hydrogen peroxide generation system according to any one of claims 1-6, characterized in that, The anode is a carbon felt electrode, and the cathode is a titanium plate.

8. The 3D electrocatalytic in-situ hydrogen peroxide generation system according to claim 7, characterized in that, The carbon felt electrode has a diameter of 2 cm and a thickness of 1-2 mm.

9. A 3D electrocatalytic in-situ hydrogen peroxide generation system according to any one of claims 1-6, characterized in that, The electrolyte is a 50-100 mmol / L Na2SO4 solution.

10. The application of the 3D electrocatalytic in-situ hydrogen peroxide generation system according to any one of claims 1 to 9 in the preparation of hydrogen peroxide.

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