Modified carbon-nitrogen material catalyst as well as preparation method and photocatalytic application thereof

Abstract

The invention relates to a modified carbon-nitrogen material catalyst as well as a preparation method and photocatalytic application thereof, and particularly discloses application of the modified carbon-nitrogen material catalyst in photocatalytic production of H2O2, and the modified carbon-nitrogen material catalyst is a thiophene ring functionalized covalent triazine framework CTF catalyst. A thiophene group is introduced into the covalent triazine frame CTF catalyst, so that the generation rate of H2O2 is greatly improved, the generation rate of H2O2 is not obviously reduced after the catalyst is recycled for multiple times, and the catalyst has excellent stability, is wide in application range, can be suitable for a wide pH value range and various complex water qualities, and has wide application prospects. And the degradation of pollutants can reach an extremely high removal rate.

Description

Technical Field

[0001] This invention relates to the field of water pollution treatment technology, specifically to a modified carbon and nitrogen material catalyst, its preparation method, and its photocatalytic application. Background Technology

[0002] Hydrogen peroxide (H2O2) is an important chemical widely used in environmental remediation, chemical industry, medical treatment and new energy fields, and its role as a clean energy carrier and green oxidant is particularly prominent.

[0003] Photocatalysis technology can utilize solar energy to directly synthesize H2O2 from water and oxygen. The photocatalytic synthesis of H2O2 typically involves two main pathways: the two-electron water oxidation reaction (WOR) and the two-electron oxygen reduction reaction (ORR). In contrast, WOR uses water as the sole feedstock, requiring no additional oxygen supply and avoiding mass transfer problems caused by the low solubility of O2, thus being considered a more environmentally friendly approach. However, its reaction rate is limited by its high reaction potential and low photogenerated hole pair separation efficiency.

[0004] Covalent organic frameworks (COFs), especially covalent triazine frameworks (CTFs), are non-metallic carbon and nitrogen materials. Due to their high specific surface area, tunable structure and excellent chemical stability, they have shown great potential in the field of photocatalysis. However, in practical applications, they suffer from insufficient active sites and severe recombination of photogenerated carriers, which are not conducive to the photocatalytic production of H2O2. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the covalent triazine framework in the prior art, which has poor effect in photocatalytic H2O2 production due to insufficient active sites and serious recombination of photogenerated carriers. Thus, the present invention provides a modified carbon and nitrogen material catalyst, its preparation method and photocatalytic application, which solves the above technical problem.

[0006] According to an embodiment of the present invention, in a first aspect, a modified carbonitriding material catalyst is provided, wherein the modified carbonitriding material catalyst is a covalent triazine framework CTF catalyst containing a thiophene ring group.

[0007] According to an embodiment of the present invention, in a second aspect, a method for preparing the modified carbon-nitrogen material catalyst described above is provided, comprising the following steps: A mixture of 1-2 mmol of a amine oxime compound, 0.5-1 mmol of a thiophene ring compound, 1-2 mmol of CsCO3 and 10-20 ml of dimethyl sulfoxide (DMSO) was subjected to gradient heating to obtain a precipitate. The precipitate was then washed and dried to obtain a modified carbonitridium catalyst.

[0008] In some embodiments of the present invention, the thiophene-containing compound includes one of 2,5-thiophene dicarboxaldehyde and thiophene[3,2-b]thiophene-2,5-dicarboxaldehyde; the geminitroxime group compound includes 1,4-digeminoximebenzene.

[0009] In some embodiments of the present invention, the molar ratio of the thiophene-containing compound to the amylopyridine group compound is 1:(1-2).

[0010] In some embodiments of the present invention, the gradient heating includes at least two stages of heating, wherein the temperature of the first stage of heating is 80-120°C and the heating time is 10-12 hours, and the temperature of the second stage of heating is 140-160°C and the heating time is 40-50 hours.

[0011] In some embodiments of the present invention, the washing includes washing the sample three or more times each with HCl solution, tetrahydrofuran solution, and deionized water; The drying process involves drying at 50-60℃ for 20-30 hours.

[0012] According to some embodiments of the present invention, in a third aspect, the application of the modified carbon-nitrogen material catalyst described above or the modified carbon-nitrogen material catalyst prepared by the preparation method described above in photocatalytic H2O2 production is provided.

[0013] In some embodiments of the present invention, the modified carbon and nitrogen material catalyst is used in the photocatalytic production of H2O2 to degrade organic pollutants in water.

[0014] In some embodiments of the present invention, the step of using modified carbon and nitrogen material catalysts to photocatalytically produce H2O2 to degrade organic pollutants in water includes: adding the modified carbon and nitrogen material catalysts to the aqueous solution to be reacted to form a reaction system, and applying light to carry out the photocatalytic reaction after reaching adsorption-desorption equilibrium under dark conditions; The aqueous solution to be reacted is an aqueous solution containing organic pollutants; The illumination wavelength λ ≥ 420 nm.

[0015] In some embodiments of the present invention, the concentration of the modified carbonitriding catalyst in the reaction system is 0.25-1 g / L; The organic pollutants include one or more of bisphenol F, fluoroquinolone antibiotics, and β-lactam antibiotics.

[0016] The technical solution of this invention has the following advantages: 1. The present invention provides an application of a modified carbon-nitrogen material catalyst in photocatalytic H2O2 production. The modified carbon-nitrogen material catalyst is a covalent triazine framework CTF catalyst containing a thiophene ring group. By introducing a thiophene ring group into the covalent triazine framework CTF catalyst, the present invention greatly improves the H2O2 generation rate. Moreover, after multiple cycles of use, the H2O2 generation rate does not decrease significantly, exhibiting excellent stability and wide applicability. It is suitable for a wide pH range and various complex water qualities, and can achieve extremely high removal rates for pollutants. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a synthetic route diagram of the catalyst prepared in the embodiments of the present invention; Figure 2 The catalysts prepared in Examples 1-2 and Comparative Example 1 of this invention are 13 C10 NMR spectrum; Figure 3 These are the FTIR spectra of the catalysts prepared in Examples 1-2 and Comparative Example 1 of this invention; Figure 4 These are XPS spectra (a) and N 1s high-resolution XPS spectra (b, c, d) of the catalysts prepared in Examples 1-2 and Comparative Example 1 of the present invention. Figure 5 These are the S 2p high-resolution XPS spectra of the materials prepared in Examples 1-2 of this invention; Figure 6 These are the XRD spectra of the catalysts prepared in Examples 1-2 and Comparative Example 1 of this invention; Figure 7 These are SEM images of the catalysts prepared in Examples 1-2 and Comparative Example 1 of this invention; Figure 8 The BET specific surface area (a) and pore size distribution (b) of the catalysts prepared in Examples 1-2 and Comparative Example 1 of this invention are shown. Figure 9 The images show the UV-vis-DRS diagram (a), Tauc diagram (b), VB binding energy diagram (c), and band structure diagram (d) of the catalysts prepared in Examples 1-2 and Comparative Example 1 of this invention. Figure 10The transient photocurrent (a), PL curve (b), fluorescence decay curve (c), and EIS curve (d) of the catalysts prepared in Examples 1-2 and Comparative Example 1 of this invention are shown. Figure 11 The photocatalytic activity of the catalysts prepared in Examples 1-2 and Comparative Example 1 for producing H2O2 in different gas atmospheres (a) and quenching systems (b) of this invention is shown. Figure 12 Linear scan RDE voltammetry plots of CTF-1 (a), CTF-TD (b), and CTF-TTD (c) measured at different rotation speeds and Koutecky-Levich plots obtained from RDE measurements (d). Figure 13 The RRDE voltammetry is obtained with the potential of the Pt ring electrode set to -0.23 V (a) and 0.6 V (b) (vs Ag / AgCl); Figure 14 These are H2O2 production effect diagrams of the catalysts prepared in Examples 1-2 and Comparative Example 1 of this invention; Figure 15 The graph (a) shows the effect of different amounts of the material prepared in Example 2 of the present invention on the H2O2 production effect, and the graph shows the decomposition effect of the catalysts prepared in Examples 1-2 and Comparative Example 1 on H2O2. Figure 16 The rate at which the catalyst prepared in Example 2 of this invention synthesizes H2O2 under different pH (a) and different water quality (b); Figure 17 The catalyst prepared in Example 2 of this invention has a rate (a) of H2O2 synthesis in 4 cycles and a yield of H2O2 synthesized in 10 hours of continuous reaction. Figure 18 The AQY of the material prepared in Example 2 of this invention at different wavelengths; Figure 19 This demonstrates the in-situ degradation performance of the catalyst prepared in Example 2 of this invention on new pollutants under visible light. Detailed Implementation

[0019] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0020] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0021] Figure 1 This is a synthetic route diagram of the catalyst prepared in the embodiments of the present invention.

[0022] Example 1 A modified carbonitridium material catalyst (CTF-TD) is prepared as follows: 1 mmol of 1,4-dieneamine oxime, 0.5 mmol of 2,5-thiophene dicarboxaldehyde, 1 mmol of CsCO3, and 10 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask. The mixture was heated using a programmed temperature rise method, stirring at 100 °C for 24 h, followed by stirring at 150 °C for 48 h, to obtain a precipitate. The precipitate was washed three times each with HCl, tetrahydrofuran solution, and pure water. After filtration, the resulting solid was dried in an oven at 60 °C for 24 h to obtain CTF-TD.

[0023] Example 2 A modified carbonitridium material catalyst (CTF-TTD) is prepared as follows: Two mmol of 1,4-dieneamine oxime, one mmol of thieno[3,2-b]thiophene-2,5-dicarboxaldehyde, two mmol of CsCO3, and two 20 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask. The mixture was heated using a programmed temperature rise method, stirring at 100 °C for 24 h, followed by stirring at 150 °C for 48 h, to obtain a precipitate. The precipitate was washed three times each with HCl, tetrahydrofuran solution, and pure water. After filtration, the resulting solid was dried in an oven at 60 °C for 24 h to obtain CTF-TTD.

[0024] Example 3 A modified carbonitridium material catalyst (CTF-TD) is prepared as follows: 1 mmol of 1,4-dieneamine oxime, 1 mmol of 2,5-thiophene dicarboxaldehyde, 1 mmol of CsCO3, and 10 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask. The mixture was heated using a programmed temperature rise method, stirring at 100 °C for 24 h, followed by stirring at 150 °C for 48 h, to obtain a precipitate. The precipitate was washed three times each with HCl, tetrahydrofuran solution, and pure water. After filtration, the resulting solid was dried in an oven at 60 °C for 24 h to obtain CTF-TD.

[0025] Example 4 A modified carbonitridium material catalyst (CTF-TTD) is prepared as follows: 1 mmol of 1,4-dieneamine oxime, 1 mmol of thieno[3,2-b]thiophene-2,5-dicarboxaldehyde, 1 mmol of CsCO3, and 10 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask. The mixture was heated using a programmed temperature rise method, stirring at 100 °C for 24 h, followed by stirring at 150 °C for 48 h, to obtain a precipitate. The sample was washed three times each with HCl, tetrahydrofuran solution, and pure water. After filtration, the resulting solid was dried in an oven at 60 °C for 24 h to obtain CTF-TTD.

[0026] Comparative Example 1 A modified carbonitriding catalyst (CTF-1) is prepared as follows: 1 mmol of 1,4-dieneamine oxime, 0.5 mmol of 1,4-benzyldiethanol, 1 mmol of CsCO3, and 10 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask. The mixture was heated using a programmed temperature rise method, stirring at 100 °C for 24 h, followed by stirring at 150 °C for 48 h, to obtain a precipitate. The sample was washed three times each with HCl, tetrahydrofuran solution, and pure water. After filtration, the resulting solid was dried in an oven at 60 °C for 24 h to obtain CTF-1.

[0027] Test case The modified carbonitriding material catalyst (CTF-TD) prepared in Example 1 and Example 3 showed no significant difference in performance and structure, and the modified carbonitriding material catalyst (CTF-TTD) prepared in Example 2 and Example 4 showed no significant difference in performance and structure. These differences will not be described in detail below.

[0028] 1. Nuclear Magnetic Resonance Spectroscopy (NMR) Spectroscopy The structures of the synthesized catalysts were characterized by NMR testing of the samples obtained in Examples 1-2 and Comparative Example 1 of this invention. Figure 2 As shown, the three CTFs 13 In the C1NMR spectrum, ~169.5 ppm corresponds to carbon atoms in the triazine ring, ~138 ppm corresponds to carbon atoms in the aromatic ring directly connected to the triazine ring, and ~128 ppm corresponds to other carbon atoms in the aromatic ring, confirming the alternating distribution of triazine and benzene rings in the CTF-1 framework structure. Further analysis of CTF-TD and CTF-TTD... 13 The C NMR spectrum, with ~145 ppm corresponding to the carbon atoms of the thiophene ring group directly attached to the triazine ring, indicates that both the thiophene ring and the thiophene ring were successfully incorporated into the CTF backbone.

[0029] 2. Fourier Transform Infrared Spectroscopy (FTIR) Test The samples prepared in Examples 1-2 and Comparative Example 1 of this invention were subjected to FTIR spectroscopy tests, such as... Figure 3 As shown, the FTIR spectra of all three are at 1508 cm⁻¹. -1 and 1358 cm -1 Two strong characteristic peaks appeared nearby, attributed to the stretching and breathing patterns of aromatic CN, indicating the formation of a triazine ring.

[0030] 3. X-ray photoelectron spectroscopy test The samples prepared in Examples 1-2 and Comparative Example 1 of this invention were subjected to X-ray photoelectron spectroscopy (XPS) tests, and the test results are as follows: Figure 4 and Figure 5 As shown. (Through) Figure 4 As shown in section a, all three CTFs contain high proportions of C and N elements. CTF-TD and CTF-TTD also show the characteristic sulfur (S) element of the thiophene ring. Further analysis of the fine spectra of N and S elements, such as... Figure 4 As shown in bd, through Figure 4 The high-resolution XPS spectra of N 1s in Figure bd show that the N 1s peaks of the three CTFs can all be deconvolved into two peaks located near 398.5 eV (N=CN) and 399.5 eV (N-(C3)), confirming the presence of triazine groups. Figure 5 a and Figure 5 As shown in Figure b, the S 2p peak near 164 eV can be further divided into two peaks: S 2p 3 / 2 and S 2p 1 / 2, further confirming the presence of thiophene groups (CSC) in the CTF-TD and CTF-TTD structures. Notably, the sulfur content and thiophene group peak intensity in CTF-TTD are significantly higher than those in CTF-TD, consistent with the trend that CTF-TTD contains a greater number of thiophene rings than CTF-TD.

[0031] 4. X-ray diffraction (XRD) test The samples prepared in Examples 1-2 and Comparative Example 1 of this invention were subjected to X-ray diffraction tests, such as... Figure 6 As shown, the three CTFs exhibit broad diffraction peaks near 2θ = 26°, attributed to the π-π stacking of the (001) plane, indicating the formation of a graphite-like two-dimensional layered structure. Furthermore, CTF-1 shows a strong diffraction peak near 2θ = 7.3°, attributed to the (100) plane, while CTF-TD and CTF-TTD do not show significant diffraction peaks at this location, indicating a higher degree of disorder in the layered structures of CTF-TD and CTF-TTD.

[0032] 5. Scanning Electron Microscopy (SEM) Testing The samples prepared in Examples 1-2 and Comparative Example 1 of this invention were tested using a scanning electron microscope (SEM). Figure 7 As shown, all three types of CTF particles exhibit irregular micron-sized morphology, but the CTF-TD and CTF-TTD particles have smoother surfaces and a more compact overall morphology.

[0033] 6. N2 adsorption isotherm test The samples prepared in Examples 1-2 and Comparative Example 1 of this invention were subjected to N2 adsorption isotherm tests, such as... Figure 8 As shown, all catalysts exhibit typical type IV isotherm characteristics, which is highly consistent with their mesoporous structure properties. Figure 8 BET surface area analysis of the three components showed that the specific surface areas of CTF-1, CTF-TD, and CTF-TTD were 235.7, 8.3, and 7.6 m², respectively. 2 ·g -1 .pass Figure 8 The data show that the introduction of thiophene groups significantly reduced the specific surface area of ​​CTF and significantly increased the pore size, which is consistent with the results observed by SEM and TEM. Furthermore, the changes in specific surface area and pore size of CTF-TTD were more significant than those of CTF-TD, further revealing the regulatory effect of thiophene groups on the pore structure of the material.

[0034] 7. Ultraviolet-Vis-NearInfrared Diffuse Reflectance (UV-Vis-DRS) and X-ray Photoelectron Spectroscopy (XPS) Valence Band Spectroscopy Analysis The samples prepared in Examples 1-2 and Comparative Example 1 of this invention were subjected to UV-Vis-DRS and XPS valence band spectroscopy tests to analyze their light absorption capacity and band structure. The analysis results are as follows: Figure 9 As shown. (Through) Figure 9 As shown in section a, the introduction of the thiophene group enhances the light absorption capacity of CTF in the visible and near-infrared regions, and the enhancement effect is more pronounced with the increase of the number of thiophene rings. Figure 9 The Tauc plot shown in Figure b further confirms that the Eg of CTF-TTD is 1.69 eV, significantly lower than that of CTF-TD (1.95 eV) and CTF-1 (2.42 eV). According to... Figure 9 From c, we can see that the calculated E values ​​of CTF-1, CTF-TD, and CTF-TTD are... VB The values ​​are +2.25, +2.21, and +2.19 V (vs. NHE), all higher than 2e. - The oxidation potential of WOR (1.76 V vs. NHE) has been corrected, indicating that the synthesis of H2O2 via WOR is thermodynamically feasible for all three methods. Furthermore, through... Figure 9 E shown in d VB Subtracting Eg yields the E values ​​of the three. CB The values ​​are -0.17, +0.26, and +0.50 V, and they also satisfy 2e- The necessary condition for ORR thermodynamically (< +0.68 V vs. NHE).

[0035] 8. Transient photocurrent, photoluminescence (PL) curves, fluorescence decay curves, and electrochemical impedance (EIS) curves were measured. To investigate the separation and migration capabilities of photogenerated carriers in the catalysts prepared in Examples 1-2 and Comparative Example 1 of this invention, transient photocurrent and photoluminescence (PL) were measured in all three samples. The results are as follows: Figure 10 As shown in a and b. (Through...) Figure 10 As shown in section a, the photocurrent response intensity of CTF-TTD is significantly higher than that of CTF-TD and CTF-1, indicating that CTF-TTD has superior photoinduced photogenerated carrier separation and migration efficiency. Figure 10 As shown in Figure b, the emission peak intensities of CTF-TD and CTF-TTD are significantly reduced and exhibit a redshift, indicating that the electron-hole pair separation efficiency of both is improved, with CTF-TTD showing a more significant improvement.

[0036] Fluorescence lifetime is an indicator of the survival time of photogenerated carriers in a catalyst; the longer the fluorescence lifetime, the lower the recombination rate of photogenerated carriers. Figure 10 The detection results shown in a and b, combined with Equations 1 and 2, are used to calculate the fluorescence lifetime of the three CTFs. The calculation results are as follows: Figure 10 As shown in c. Through as... Figure 10 As shown in Figure c, the fluorescence lifetime of CTF-TTD (3.05 ns) is significantly larger than that of CTF-TD (1.62 ns) and CTF-1 (1.22 ns), indicating that CTF-TTD induces slower recombination of photogenerated carriers.

[0037] In addition, the electrochemical impedance spectroscopy (EIS) of the three components was measured, and the results are as follows: Figure 10 As shown in d, through Figure 10 As shown in Figure d, the EIS curves of the three components reveal that CTF-TTD has the smallest semicircle radius, demonstrating its superior charge transport capability. These results indicate that the introduction of thiophene groups can modulate the photocatalytic activity of CTF; the greater the number of thiophene rings, the more significant the promoting effect on the separation and transport of photogenerated carriers.

[0038] (Equation 1) (Equation 2).

[0039] In the formula, I(t): intensity, τ: decay time, τ1: decay time caused by nonradiative recombination, τ2: decay time caused by free exciton recombination, A1 and A2: relative amplitude.

[0040] 9. Mechanism Investigation The active species and mechanisms of the catalysts prepared in Examples 1-2 and Comparative Example 1 of this invention were identified. A series of controlled experiments and electrochemical tests were conducted to study the synthesis of H2O2 from the three CTFs under visible light, as detailed below: 1) The H2O2 yield was obtained by replacing air with Ar as the reaction atmosphere. The H2O2 yield results are as follows: Figure 11 As shown in Figure a. (Through) Figure 11 As shown in Figure a, the H2O2 yield of all CTFs decreased slightly, while the yield increased only slightly when O2 was used to replace air. This indicates that the O2 in the air can basically meet the reaction requirements of the three CTF systems, and H2O2 can be synthesized significantly even under O2-deficient conditions. Based on this, it can be inferred that all three CTF systems involve two processes: the two-electron oxygen reduction reaction (ORR) and the two-electron water oxidation reaction (WOR), with WOR playing a dominant role in the CTF-TTD reaction system.

[0041] 2) To verify O2 •- , • To investigate whether OH participates in the ORR and WOR processes of H2O2 synthesis, a quenching experiment was conducted. The experimental procedure was identical to the photocatalytic H2O2 synthesis experiment described in Application Example 1 below, except that a certain amount of quencher was added before turning on the light source. In this experiment, chloroform (TCM) and tert-butanol (TBA) were selected as O2. •- and • OH quencher, H2O2 yield detected. (By...) Figure 11 As shown in b, the H2O2 production rates of CTF-1 and CTF-TD did not decrease after the addition of TCM and TBA, respectively, indicating that O2 production... •- , • OH is not a necessary reactive species for the synthesis of H2O2 from either of the two quenchers. Although the yield of H2O2 decreased more significantly after the addition of both quenchers in the CTF-TTD system, the decrease was not large (<20%), indicating that O2 production was relatively low. •- , • OH did not play a key role in the CTF-TTD system.

[0042] 3) Further analysis of the ORR selectivity of H2O2 generation was performed using RDE testing. The detection results are as follows: Figure 12 As shown in Figure 1, the average electron transfer numbers involved in the ORR of CTF-1, CTF-TD, and CTF-TTD are 1.32, 2.24, and 1.98, respectively, with CTF-TTD being closest to an ORR electron transfer number of 2. Therefore, all CTF catalysts can pass through the 2e⁻¹ ORR. - The ORR pathway reduces O2 to H2O2, with CTF-TTD exhibiting the highest reaction selectivity.

[0043] 4) Further study of the WOR process of the three CTFs was conducted using RRDE measurement and analysis. Specifically, a constant voltage of -0.23 V (vs Ag / AgCl, the same below) was applied to the Pt ring electrode at 10 mV s. -1 The scanning rate was increased from 0.8 V to 2.0 V at the rotating disk electrode. The change in oxidation current at the rotating disk electrode was observed to determine if the WOR process occurred. The change in reduction current at the Pt ring electrode was observed to determine if O2 was generated (O2 generated at the rotating disk electrode was swept onto the Pt ring electrode). The analysis results are as follows: Figure 13 As shown. (Through) Figure 13 As shown in section a, when the voltage of the rotating disk electrode is greater than 1.4 V, all three CTFs exhibit significant oxidation currents, with the current magnitude showing the order CTF-TTD > CTF-TD > CTF-1. This trend becomes more pronounced with further increases in the rotating disk electrode voltage. However, no significant change in reduction current was observed at the Pt ring electrode. This indicates that WOR (Warning-Oriented Reduction) occurred at the rotating disk electrode for all three, but no O2 was generated. When the constant voltage applied to the Pt ring electrode was adjusted to +0.6 V, and the voltage of the rotating disk electrode was increased from 0.8 V to 2.0 V at the same scan rate, the change in oxidation current at the Pt ring electrode was observed to determine whether H2O2 was generated. Figure 13 As shown in Figure b, when the voltage of the rotating disk electrode is greater than 1.5 V, all three CTFs exhibit significant oxidation currents, showing a trend of CTF-TTD > CTF-TD > CTF-1, confirming the formation of H2O2. RRDE test results indicate that all three CTFs tend to generate H2O2 via 2e-. - WOR generates H2O2, instead of 4e. - WOR generates O2, and CTF-TTD can be generated via 2e. - WOR generates more H2O2.

[0044] Based on the above analysis, the pathways for the generation of H2O2 by the three CTF-based catalysts are as follows: direct 2e - ORR (Equation 3) and direct 2e - WOR (Equation 4) dual path, (Equation 3) (Equation 4).

[0045] Among them, direct 2e - WOR plays a major role; in WOR, H2O is not only oxidized to H2O2, but also generates protons, which further participate in and promote the ORR reaction, and the consumption of protons further promotes the WOR process.

[0046] Application Example 1 The modified carbonitriding material catalyst (CTF-TD) prepared in Example 1 and Example 3 showed no significant difference in performance and structure, and the modified carbonitriding material catalyst (CTF-TTD) prepared in Example 2 and Example 4 showed no significant difference in performance and structure. These differences will not be described in detail below.

[0047] 1. Photocatalytic synthesis of H2O2 experiment 15 mg of catalyst and 30 mL of water (or an aqueous solution containing a sacrificial agent) were added to a quartz reactor. The suspension was sonicated for 10 min to ensure thorough dispersion, followed by stirring in the dark for 30 min to reach adsorption-desorption equilibrium. A 300 W xenon lamp (λ > 420 nm) was used as the light source, and the temperature was maintained at 25 °C using a circulating water system. At specific time points, 1 mL of sample was collected and filtered through a filter with a 0.22 μm filter membrane. Finally, the H₂O₂ concentration was determined using a UV spectrophotometer.

[0048] The amount of H2O2 generated was determined by iodometric titration. The sample was diluted to a certain factor, and 3 mL of the diluted sample was placed in a quartz tube. 1 mL of KI (0.4 M) and 1 mL of C8H5O4K (0.1 M) were added and mixed thoroughly. After allowing the mixture to stand for 30 min, the absorbance was measured at 350 nm using a UV spectrophotometer to determine the concentration of H2O2 generated in each sample.

[0049] The photocatalytic performance of the catalysts prepared in Examples 1-2 and Comparative Example 1 for synthesizing H2O2 was studied using the experimental methods described above. Figure 14 As shown, after 90 min of visible light irradiation, the H2O2 photosynthetic rate of CTF-TTD reached 1730 µmol·g. -1 ·h -1 They are CTF-TD (1082 µmol·g) -1 ·h -1 ) and CTF-1 (664 µmol·g -1 ·h -1 The H2O2 formation rate was 1.6 and 2.6 times higher than that of most reported catalysts. This result indicates that the introduction of the thiophene group significantly increased the H2O2 formation rate, and the promoting effect became more pronounced with the increase of the thiophene ring.

[0050] 2. Effect of different catalyst dosages on the H2O2 synthesis rate The effects of different catalyst dosages obtained in Examples 1-2 and Comparative Example 1 on the H2O2 synthesis rate were investigated. Figure 15 As shown in Figure a, 0.5 g L -1This is the optimal catalyst concentration for CTF-TTD. Further increasing the catalyst dosage will inhibit light absorption, thus reducing the H2O2 synthesis rate. To verify whether the prepared catalyst catalyzes H2O2 decomposition under light irradiation, its decomposition performance for H2O2 was tested under visible light and in an air atmosphere. Figure 15 As shown in Figure b, after the initial addition of 1 mM H2O2 and irradiation with visible light for 1.5 h, no decrease in H2O2 concentration was observed in any of the three CTFs. On the contrary, their concentration values ​​increased significantly during the reaction process, indicating that the decomposition side reaction rate of H2O2 by the three is much smaller than the formation rate, which helps to stably synthesize high concentration H2O2.

[0051] 3. Effects of pH value and different water qualities on H2O2 synthesis performance Following the experimental methods described in the photocatalytic synthesis of H2O2 experiment, the performance of the catalyst prepared in Example 2 of this invention in synthesizing H2O2 within different pH ranges and in various aquatic environments was systematically evaluated. Figure 16 As shown in Figure a, the rate of H2O2 synthesis by CTF-TTD in pure water with a pH range of 5.04 to 9.01 remains almost unchanged. Even when the pH of the water decreases to 3.03, the H2O2 synthesis rate only decreases slightly (the decrease is <7.1%), demonstrating the stability and applicability of the catalyst over a wide pH range.

[0052] CTF-TTD also shows good application potential under more complex aquatic matrix conditions. For example... Figure 16 As shown in Figure b, when the pure water in the experiment was replaced with river water and seawater, the CTF-TTD values ​​were 779 and 360 µmol·g, respectively. -1 ·h -1 The photosynthetic efficiency of H2O2 is high. Although its H2O2 synthesis performance is significantly lower than that in a pure water environment, by increasing the amount of catalyst or extending the reaction time, the accumulated H2O2 can still meet the concentration requirements for practical use, highlighting its application potential in pollutant degradation and disinfection.

[0053] 4. Stability and reusability performance evaluation In addition to its excellent photocatalytic performance in H2O2 synthesis, the CTF-TTD prepared in Example 2 of this invention also possesses good stability and applicability. Figure 17 As shown in Figure a, CTF-TTD maintained a H2O2 synthesis rate of 1570.6 µmol·g in four consecutive cycles of the experiment, although the H2O2 synthesis rate decreased. -1 ·h -1 The H2O2 synthesis rate exhibits excellent reusability. Figure 17Further analysis in Figure b shows that CTF-TTD / pure water produces 4 mM H2O2 after 10 h of visible light irradiation, which meets the concentration requirements for water purification. In particular, when 10% benzyl alcohol is added as a quencher, the H2O2 production after 10 h of visible light irradiation increases by 11.8 times (47 mM), highlighting its excellent application potential.

[0054] 5. Apparent quantum efficiency (AQY) The apparent quantum efficiency (AQY) of the catalyst was measured using a multi-channel photocatalytic reaction system (PCX-50C Discover). All light sources were single-wavelength LEDs with wavelengths of 420, 450, 485, 520, and 595 nm. Other experimental procedures were consistent with the photocatalytic synthesis of H₂O₂. AQY is an important indicator of the efficiency of photochemical reactions in photosynthesis. Figure 18 As shown, CTF-TTD exhibits an AQY of 4.11% at 420 nm.

[0055] Application Example 2 1. Pollutant Degradation Experiment The degradation performance of the catalyst on novel pollutants was studied using a quartz reactor equipped with a xenon lamp light source. The specific experimental procedures were as follows: A certain amount of catalyst and 30 mL of pollutant at a certain concentration were added to the quartz reactor, and the mixture was magnetically stirred at 25°C in the dark for 30 min to reach adsorption-desorption equilibrium. Subsequently, the light source was turned on to trigger photocatalytic degradation. At a predetermined time point, a certain amount of reaction solution was removed from the reactor, filtered through a 0.22 µm polyethersulfone membrane, and an equal volume of methanol (MeOH) was immediately added to the filtrate. After thorough mixing, the solution was transferred to a sample vial for subsequent analysis. It should be noted that when performing enrofloxacin (ENR) degradation experiments, the filtered sample did not require the addition of MeOH and could be directly used for UV-Vis spectrophotometric analysis.

[0056] The concentrations of novel contaminants such as bisphenol F (BPF) and nimesulide (NIM) were determined using high-performance liquid chromatography (HPLC, Waters e2695). The HPLC system was equipped with an Agilent C-18 column (4.6 mm × 250 mm, 5 µm), with 0.1% HCOOH, methanol (MeOH), and acetonitrile (MeCN) as mobile phases A, B, and C, respectively. Detailed HPLC settings for each contaminant are shown in Table 1. The concentration of ENR was analyzed using a UV-Vis spectrophotometer at a detection wavelength of 271 nm.

[0057] Table 1. HPLC test methods for different organic pollutants

[0058] Referring to the pollutant degradation experimental methods described above, degradation experiments were conducted on the catalyst prepared in Example 2 of this invention. BPF, ENR, and NIM were selected as typical target new pollutants for in-situ degradation experiments. Figure 19 As shown, the CTF-TTD system achieved complete degradation of all three target novel pollutants within 60 minutes. This result not only confirms the significant advantage of the CTF-TTD system in efficiently degrading novel pollutants, but also indicates its broad application potential in the field of environmental pollution control.

[0059] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A modified carbonitriding catalyst, characterized in that, The modified carbon-nitrogen material catalyst is a covalent triazine framework CTF catalyst containing a thiophene ring group.

2. The method for preparing the modified carbonitriding catalyst as described in claim 1, characterized in that, Includes the following steps: A mixture of 1-2 mmol of a amine oxime compound, 0.5-1 mmol of a thiophene ring compound, 1-2 mmol of CsCO3 and 10-20 ml of DMSO was subjected to gradient heating to obtain a precipitate. The precipitate was then washed and dried to obtain a modified carbonitridium catalyst.

3. The preparation method according to claim 2, characterized in that, The thiophene-containing compound includes one of 2,5-thiophene dicarboxaldehyde and thiophene[3,2-b]thiophene-2,5-dicarboxaldehyde; the geminitroxime compound includes 1,4-digeminoxime benzene.

4. The preparation method according to claim 2 or 3, characterized in that, The molar ratio of the thiophene-containing compound to the amylopyridine group compound is 1:(1-2).

5. The preparation method according to any one of claims 2-4, characterized in that, The gradient heating includes at least two heating stages. The first stage of heating has a temperature of 80-120℃ and a heating time of 10-12 hours. The second stage of heating has a temperature of 140-160℃ and a heating time of 40-50 hours.

6. The preparation method according to any one of claims 2-5, characterized in that, The washing process includes washing the sample three or more times each with HCl solution, tetrahydrofuran solution, and deionized water. The drying process involves drying at 50-60℃ for 20-30 hours.

7. The application of a modified carbonitriding material catalyst as described in claim 1 or a modified carbonitriding material catalyst prepared by any one of claims 2-6 in photocatalytic H2O2 production.

8. The application according to claim 7, characterized in that, The modified carbon and nitrogen material catalyst is used in the photocatalytic production of H2O2 to degrade organic pollutants in water.

9. The application according to claim 8, characterized in that, The steps of using modified carbon and nitrogen materials as catalysts for photocatalytic H2O2 degradation of organic pollutants in water include: adding the modified carbon and nitrogen materials as catalysts to the aqueous solution to form a reaction system, reaching adsorption-desorption equilibrium under dark conditions, and then applying light to carry out the photocatalytic reaction; The aqueous solution to be reacted is an aqueous solution containing organic pollutants; The illumination wavelength λ ≥ 420 nm.

10. The application according to any one of claims 7-9, characterized in that, The concentration of the modified carbonitriding catalyst in the reaction system is 0.25-1 g / L; The organic pollutants include one or more of bisphenol F, fluoroquinolone antibiotics, and β-lactam antibiotics.

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