Highly selective K + Method for preparing intercalated porous layered g-c3n4 and photocatalytic applications

Abstract

The application belongs to the technical field of photocatalytic materials, and relates to a high-selectivity K + A preparation method of intercalated porous layered g-C3N4: thiocyanic acid, ammonium chloride and potassium chloride are fully ground to obtain a white solid mixture, wherein the mass ratio of the thiocyanic acid, the ammonium chloride and the potassium chloride is 1:2-6:0.015-0.09; the white solid mixture is calcined at a temperature rising rate of 1-3 DEG C / min to 500-550 DEG C for 3-5 h, and after being cooled to room temperature, the obtained yellow solid is washed and dried, and the intercalated porous layered g-C3N4 is obtained. The application also discloses application of the material in photocatalytic production of H2O2. The prepared intercalated porous layered g-C3N4 has the advantages of narrow band gap and enhanced reduction capacity. + The intercalated porous layered g-C3N4 has narrow band gap and enhanced reduction capacity, K + The introduction of the K can effectively inhibit the recombination of photo-generated carriers, the porous structure can significantly improve the 2e ‑ ORR selectivity, thereby greatly improving the photocatalytic production of H2O2 performance of the K + Intercalated porous layered g-C3N4.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, and relates to photocatalysts, specifically a highly selective K... + Preparation method and photocatalytic application of intercalated porous layered g-C3N4. Background Technology

[0002] H₂O₂ is a highly efficient and environmentally friendly oxidant with the highest active oxygen content (47.1% w / w). It produces no toxic byproducts during the reaction, generating only H₂O and O₂. Due to these advantages, H₂O₂ has been widely used in organic synthesis, wastewater treatment and disinfection, and the pulp and paper industry. Photocatalytic production of H₂O₂ requires only water and O₂ as raw materials, sunlight as the energy source, and semiconductor materials as the photocatalyst. Moreover, the production process is pollution-free, making it a safe and green method for producing H₂O₂. Among many photocatalysts, g-C₃N₄, composed of carbon and nitrogen, is characterized by its low cost, easy availability, high physicochemical stability, suitable band structure, and ease of control, making it widely used in photocatalytic reactions.

[0003] Carbon nitride has been widely reported in the field of photocatalytic H2O2 production. Modified carbon nitride is prepared through methods such as elemental doping or defect construction, and its photocatalytic performance is improved by enhancing its photoresponse capability and suppressing the recombination of photogenerated carriers. It is well known that improving the H2O2 selectivity of catalysts is also one of the important ways to enhance the performance of photocatalytic H2O2 production. On the one hand, through K... + Doping can controllably adjust the band structure of carbon nitride and suppress charge recombination. On the other hand, it introduces a porous structure, which significantly enhances the 2e-energy dissipation of the catalyst. - ORR selectivity, thereby increasing the yield of H2O2. Summary of the Invention

[0004] To address the shortcomings of the existing technology, the purpose of this invention is to provide a highly selective K... + A method for preparing intercalated porous layered g-C3N4.

[0005] Technical solution

[0006] A highly selective K + The preparation method of intercalated porous layered g-C3N4 includes the following steps:

[0007] (1) Thiourea, ammonium chloride and potassium chloride are thoroughly ground to obtain a white solid mixture, wherein the mass ratio of thiourea, ammonium chloride and potassium chloride is 1:2 to 6:0.015 to 0.09;

[0008] (2) The resulting white solid mixture was heated to 500–550°C at a heating rate of 1–3°C / min for 3–5 hours. After cooling to room temperature, the resulting yellow solid was washed and dried to obtain K. + Intercalated porous layered g-C3N4.

[0009] In a preferred embodiment of the present invention, the mass ratio of thiourea, ammonium chloride and potassium chloride in step (1) is 1:4:0.05.

[0010] In the preferred embodiment of the present invention, the calcination temperature in step (2) is 520°C, the calcination time is 4 hours, and the heating rate is 2°C / min.

[0011] In a preferred embodiment of the present invention, the yellow solid in step (2) is ground into powder, washed with distilled water at 60°C, centrifuged, and dried to obtain K. + Intercalated porous layered g-C3N4.

[0012] K prepared by the method described in this invention + Intercalated porous layered g-C3N4, the material has a layered structure, K + Intercalated porous layered g-C3N4 possesses a controllable band structure, excellent electron transport capability, and high 2e energy. - ORR selectivity enables efficient photocatalytic production of H2O2.

[0013] Another object of the present invention is to produce K + Intercalated porous layered g-C3N4 is used for photocatalytic H2O2 production.

[0014] Experimental steps:

[0015] S1, based on K + Intercalated porous layered g-C3N4 was placed in a reaction vessel, and an aqueous ethanol solution was added. The mixture was stirred until K + Intercalated porous layered g-C3N4 is uniformly dispersed in an ethanol-water solution;

[0016] S2. Place the reaction vessel in the photocatalytic reactor, stir continuously, and irradiate with a 300W xenon lamp (λ≥420nm) to obtain H2O2.

[0017] Wherein, K in step S1 + The mass-to-volume ratio of intercalated porous layered g-C3N4 to ethanol aqueous solution is 0.0005–0.001:1 g / mL, and the volume fraction of ethanol aqueous solution is 10–15%.

[0018] The illumination time in step S2 is 50 to 70 minutes.

[0019] The advantage of this invention lies in the K prepared+ Intercalated porous layered g-C3N4 exhibits a narrow band gap and enhanced reduction capability. Meanwhile, K... + The introduction of porous structures can effectively suppress the recombination of photogenerated carriers, and the porous structure can significantly improve the 2e - ORR selectivity, thereby greatly improving K + Photocatalytic H2O2 production performance of intercalated porous layered g-C3N4.

[0020] Beneficial effects

[0021] This invention, through the introduction of potassium (K) element doping and a porous structure, can effectively enhance the photocatalytic H2O2 production performance of g-C3N4. Under air conditions, the optimal activity of K is achieved. + The H2O2 yield of intercalated porous layered g-C3N4 can reach 781.39 μM, which is the highest among potassium-free materials. + The intercalated g-C3N4 has 8.6 times the efficiency. The modified carbon nitride proposed in this invention has high 2e content. - ORR selectivity, especially for KUCN9 at 0.3V vs. RHE, can reach 94.5% H2O2 selectivity. Attached Figure Description

[0022] Figure 1 K prepared in the example + XRD pattern of intercalated porous layered g-C3N4 (KUCNx);

[0023] Figure 2 K prepared in the example + SEM image of intercalated porous layered g-C3N4 (KUCNx) (the precursor ratio of the sample is: thiourea to ammonium chloride mass ratio is 1:2, and the mass ratio of ammonium chloride to potassium chloride is 0.08);

[0024] Figure 3 K prepared in the example + Solid UV diffuse reflectance pattern of intercalated porous layered g-C3N4 (KUCNx) (the ratio of the precursors in the sample is: thiourea to ammonium chloride mass ratio is 1:2, and the mass ratio of ammonium chloride to potassium chloride mass ratio is 0.08);

[0025] Figure 4 K prepared in the example + Pore ​​size distribution of intercalated porous layered g-C3N4 (KUCNx) (the ratio of the precursors in the sample is: thiourea to ammonium chloride mass ratio is 1:2, and the mass ratio of ammonium chloride to potassium chloride mass ratio is 0.08);

[0026] Figure 5 K prepared in the example +Photocurrent plot of intercalated porous layered g-C3N4 (KUCNx) (the ratio of the precursors in the sample is: thiourea to ammonium chloride mass ratio is 1:2, and the mass ratio of ammonium chloride to potassium chloride mass ratio is 0.08);

[0027] Figure 6 K prepared in the example + Photocatalytic H2O2 production curve of intercalated porous layered g-C3N4 (KUCNx) under visible light irradiation time (the mass ratio of the precursors in the sample is: thiourea to ammonium chloride is 1:2, and the mass ratio of ammonium chloride to potassium chloride is 0.08).

[0028] Figure 7 K prepared in the example + H2O2 selectivity of intercalated porous layered g-C3N4 (KUCNx) at 1600 rpm (the ratio of the sample precursors was: thiourea to ammonium chloride mass ratio of 1:2, and ammonium chloride to potassium chloride mass ratio of 0.08). Detailed Implementation

[0029] The present invention will be described in detail below with reference to embodiments, so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following embodiments.

[0030] A highly selective K + The preparation method of intercalated porous layered g-C3N4 includes the following steps:

[0031] Step 1: Place 2.0g of thiourea, 4.0g of ammonium chloride and xg (x = 0.00, 0.03, 0.05, 0.07 and 0.09) of potassium chloride in a mortar and grind them thoroughly to obtain a white solid mixture;

[0032] Step 2: The resulting white solid mixture was calcined at 520℃, with a heating rate of 2℃ / min and a holding time of 4 hours. After cooling to room temperature, a yellow solid was obtained. The yellow solid was then washed and dried to obtain K. + Intercalated porous layered g-C3N4.

[0033] For details on the application of the prepared catalyst to the photocatalytic production of H2O2, please refer to the description of the invention.

[0034] Figure 1 As the KCl content increased, the intensity of the characteristic peak of the KUCNx sample increased and the position of the peak shifted, while other aspects remained unchanged.

[0035] Figure 2 The prepared sample shows a layered structure.

[0036] Figure 3 As shown in the figure, K was successfully introduced into the structure of modified carbon nitride.+ .

[0037] Figure 4 In the process, KUCNx exhibits enhanced light absorption in the visible light region and develops new absorption bands, which is beneficial for improving photocatalytic performance.

[0038] Figure 5 The pore size distribution diagram shows that the prepared sample has a porous structure.

[0039] Figure 6 Zhong K + The doped sample exhibited a stronger photocurrent intensity, indicating that it had better photoelectric carrier separation efficiency, thereby promoting the photocatalytic production of H2O2.

[0040] Figure 7 The graph shows the photocatalytic production curve of H2O2 under visible light irradiation. Under visible light irradiation, a mixed solution of ethanol and water with a volume ratio of 1:9, a catalyst mass of 30 mg, and a mixed solution of 30 mL are sufficient for effective photocatalytic production of H2O2. The K2 concentration can be clearly observed in the graph. + The activity of intercalated porous layered g-C3N4 (KUCNx) was significantly enhanced, likely due to the absence of K. + The intercalation efficiency was 8.6 times that of g-C3N4. Furthermore, it was found that KUCN9 exhibited 94.5% H2O2 selectivity at 0.3V vs. RHE.

[0041] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A highly selective K + The application of intercalated porous layered g-C3N4 is characterized by, Its application in photocatalytic H2O2 production includes the following steps: S1, Select K with high selectivity + Intercalated porous layered g-C3N4 was placed in a reaction vessel, and an aqueous ethanol solution was added. The mixture was stirred until K + Intercalated porous layered g-C3N4 is uniformly dispersed in an ethanol-water solution; S2. Place the reaction vessel in the photocatalytic reactor, stir continuously, and irradiate with a 300W xenon lamp with a wavelength λ≥ 420 nm to obtain H2O2; Among them, the highly selective K mentioned in step S1 + The preparation method of intercalated porous layered g-C3N4 includes the following steps: (1) Thiourea, ammonium chloride and potassium chloride are thoroughly ground to obtain a white solid mixture, wherein the mass ratio of thiourea, ammonium chloride and potassium chloride is 1:2 to 6:0.015 to 0.09; (2) The resulting white solid mixture was heated to 500–550 °C at a heating rate of 1–3 °C / min for 3–5 h. After cooling to room temperature, the resulting yellow solid was ground into powder, washed with distilled water at 60 °C, centrifuged, and dried to obtain K. + Intercalated porous layered g-C3N4.

2. The highly selective K according to claim 1 + The application of intercalated porous layered g-C3N4 is characterized by: In step S1, the K + The mass-to-volume ratio of intercalated porous layered g-C3N4 to ethanol aqueous solution is 0.0005–0.001:1 g / mL, and the volume fraction of ethanol aqueous solution is 10–15%.

3. The highly selective K according to claim 1 + The application of intercalated porous layered g-C3N4 is characterized by: The illumination time in step S2 is 50–70 min.

4. The highly selective K according to claim 1 + The application of intercalated porous layered g-C3N4 is characterized by: In step (1), the mass ratio of thiourea, ammonium chloride and potassium chloride is 1:4:0.

05.

5. The highly selective K according to claim 1 + The application of intercalated porous layered g-C3N4 is characterized by: In step (2), the calcination temperature is 520 ℃, the calcination time is 4 h, and the heating rate is 2 ℃ / min.

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