Sodium-doped carbon nitride cerium dioxide heterojunction photocatalytic material as well as preparation and application thereof

Abstract

The invention discloses a sodium-doped carbon nitride cerium dioxide heterojunction photocatalytic material as well as preparation and application thereof. The photocatalytic material comprises lamellar sodium-doped carbon nitride and CeO2 spherical particles dispersed on the surface of the lamellar sodium-doped carbon nitride, and the sodium-doped carbon nitride and CeO2 form a heterojunction. The preparation method comprises the following steps: uniformly mixing organic amine and a sodium source, calcining, and washing to obtain sodium-doped carbon nitride; dispersing sodium-doped carbon nitride and CeO2 in the liquid, and fully mixing to obtain a suspension; and centrifuging the suspension, taking the precipitate, and drying to obtain the heterojunction photocatalytic material. According to the invention, through the heterojunction formed by sodium-doped carbon nitride and CeO2 nanoparticles, the transfer of photon-generated carriers is promoted, the utilization rate of sunlight is improved, the photocatalytic oxidation desulfurization performance of the photocatalytic material is synergistically improved, and the photocatalyst can be applied to the efficient degradation of thiophene sulfides difficult to remove in fuel oil.

Description

Technical Field

[0001] This invention relates to a heterojunction photocatalytic material, its preparation and application, and more particularly to a sodium-doped carbon nitride cerium dioxide heterojunction photocatalytic material, its preparation and application in photocatalytic oxidation desulfurization. Background Technology

[0002] With the continuous upgrading of fuel cleanliness standards, the removal of thiophene (TH) and other sulfides from fuel has become a key challenge in the industry. Current mainstream desulfurization technologies have many limitations: hydrodesulfurization (HDS) is ineffective at removing thiophene sulfides and requires high temperature, high pressure, and expensive catalysts, resulting in high energy consumption and costs; adsorption desulfurization (ADS) has insufficient adsorbent regeneration capacity, making it difficult to adapt to large-scale applications; physical extraction desulfurization (EDS) has a complex solvent recovery process; biological desulfurization (BDS) has low catalyst efficiency and a long reaction cycle; and chemical oxidation desulfurization (ODS) is prone to generating secondary pollution.

[0003] Photocatalytic oxidation desulfurization (PODS) has become a research hotspot due to its advantages of being green, environmentally friendly, and low-cost. However, its core photocatalysts still have shortcomings: pure graphitic carbon nitride (g-C3N4) has a blocky, stacked layered structure with a small specific surface area, few active sites, a wide band gap, and a fast photogenerated electron-hole recombination rate, resulting in limited photocatalytic activity. Some modified photocatalysts have problems such as poor interfacial contact and high carrier transfer resistance, failing to achieve an effective balance between desulfurization efficiency and practicality, and cannot meet the requirements for deep removal of thiophene sulfides. Summary of the Invention

[0004] Objectives of this invention: The objective of this invention is to provide a sodium-doped cerium carbon nitride (CNO) heterojunction photocatalytic material, addressing the problem of poor oxidative desulfurization performance in existing photocatalytic degradation materials. A second objective is to propose a method for preparing this sodium-doped CNOOC heterojunction photocatalytic material, solving the problem of how to prepare such a material. A third objective is to propose the application of this sodium-doped CNOOC heterojunction photocatalytic material in the photocatalytic degradation of sulfur-containing compounds in fuel oil, solving the problem of how to photocatalytically degrade sulfur-containing compounds in fuel oil.

[0005] Technical solution: The sodium-doped carbon nitride cerium dioxide heterojunction photocatalytic material of the present invention includes thin sheet-like sodium-doped carbon nitride and CeO2 spherical particles dispersed on its surface, wherein the sodium-doped carbon nitride and CeO2 form a heterojunction.

[0006] The second aspect of this invention discloses a method for preparing the above-mentioned sodium-doped carbon nitride cerium dioxide heterojunction photocatalytic material, comprising the following steps: (1) After mixing organic amine and sodium source, calcination and washing are performed to obtain sodium-doped carbon nitride; (2) Sodium-doped carbon nitride and CeO2 are dispersed in a liquid and mixed thoroughly to obtain a suspension; (3) Centrifuge the suspension to collect the precipitate, and dry it to obtain the heterojunction photocatalytic material.

[0007] Preferably, in step (1), the organic amine includes at least one of melamine, urea, and dicyandiamide; and the sodium source includes at least one of sodium chloride, sodium carbonate, sodium sulfate, and sodium nitrate.

[0008] Preferably, in step (1), the mass ratio of organic amine to sodium source is 5-15:1-10. Preferably, in step (1), the mixing method is as follows: The organic amine and sodium source were dispersed in an alcohol solvent and mixed to obtain a first mixture; the alcohol solvent was removed from the first mixture to obtain a mixed solid. The calcination conditions are as follows: the mixed solid of organic amine and sodium source is heated from room temperature to 500-600℃ at a rate of 1-10℃ / min and held at that temperature for 1-10h; The washing method is as follows: after grinding the calcined product into powder, it is washed with water to remove residual sodium chloride, and then the washed powder is dried to obtain sodium-doped carbon nitride.

[0009] Furthermore, the alcohol solvent includes at least one of methanol, ethanol, and propanol.

[0010] Preferably, in step (2), the mass ratio of sodium-doped carbon nitride to CeO2 is 25-75:10-40.

[0011] Preferably, in step (2), the liquid is at least one of water, methanol, ethanol, and propanol.

[0012] The third aspect of this invention discloses the application of the heterojunction photocatalytic material prepared by the above-described method in the photocatalytic degradation of sulfur-containing compounds in fuel oil.

[0013] Preferably, the sulfur-containing compound includes at least one of thiophene, thiophene derivatives, cyclic sulfides, disulfides, thioethers, thiols, and hydrogen sulfide.

[0014] In some embodiments, the concentration of sulfur compounds in the fuel oil does not exceed 500 ppm, preferably 100-300 ppm.

[0015] In some embodiments, the feed-to-liquid ratio of heterojunction photocatalytic material to fuel oil is 10-50 mg: 10-50 mL.

[0016] In some embodiments, the photocatalytic degradation method involves irradiating a mixture of heterojunction photocatalytic material and fuel with a light source in an air atmosphere for 1-5 hours to continuously degrade the mixture.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) From the morphological level, sodium doping in this invention transforms the blocky, layered structure of g-C3N4 into a sheet structure, significantly increasing the specific surface area and active sites. At the same time, CeO2 nanoparticles can be uniformly dispersed on the surface of Na-C3N4 sheets, forming a tight heterojunction with no obvious agglomeration. From the carrier transport level, PL spectral characterization shows that g-C3N4 has the highest fluorescence intensity and the lowest carrier separation efficiency. After sodium doping, the fluorescence intensity of Na-C3N4 decreases and the carrier separation efficiency increases. However, sodium doping alone does not significantly improve the photocatalytic oxidation desulfurization performance of C3N4 material. Only after Na-C3N4 further forms a heterojunction with CeO2 particles can it significantly suppress the recombination rate of photogenerated electrons and holes, significantly improve the carrier separation and transfer efficiency, and thus obtain excellent photocatalytic performance.

[0018] (2) In the application of photocatalytic oxidation desulfurization, the desulfurization conversion rate of thiophene in fuel oil is significantly higher than that of existing g-C3N4 materials, reaching more than 90%. The core reason is that the heterojunction structure promotes the transfer of photogenerated carriers, improves the utilization rate of sunlight, and realizes the efficient degradation of thiophene-type difficult-to-remove sulfur compounds.

[0019] (3) The raw materials used in this invention are common reagents such as melamine, sodium chloride, and commercial CeO2, which are widely available and inexpensive. The preparation process does not require harsh conditions such as high temperature and high pressure. The muffle furnace calcination, ultrasonic dispersion, and centrifugal drying processes are simple to operate and the energy consumption is much lower than that of traditional hydrodesulfurization technology. The desulfurization process uses air as the oxidation medium and does not require the addition of harmful oxidants, which is in line with the concept of green chemical industry. Moreover, the material structure is highly stable and has high potential for industrial application. Attached Figure Description

[0020] Figure 1 SEM images of samples from different materials; Figure 2 TEM images of samples from different materials; Figure 3 The images show the HRTEM image and EDS spectrum of the Na-C3N4 / CeO2 sample prepared in Example 1. Figure 4 XRD patterns for different materials; Figure 5 FTIR spectra of different materials; Figure 6 PL spectra of different materials; Figure 7 The results show the photocatalytic oxidation desulfurization performance of thiophene on different materials. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0022] Example 1: A method for preparing a sodium-doped carbon nitride cerium dioxide heterojunction photocatalytic material is as follows: (1) Preparation of Na-C3N4: Weigh 10g of melamine and 5g of sodium chloride, put them into a 50mL glass beaker, add 30mL of anhydrous ethanol, place the beaker on a magnetic stirrer, and stir at 250r / min for 6h to ensure that the materials are mixed evenly. After stirring, transfer to a drying oven and dry overnight at 72℃ until the ethanol is completely evaporated to obtain a mixed solid.

[0023] The mixed solids were loaded into a covered crucible, which was then placed in a muffle furnace. An air atmosphere and a heating program were set: the temperature was increased from room temperature to 550℃ at a rate of 3.5℃ / min, and the temperature was maintained for 6 hours to complete the thermal polymerization. After cooling, the mixture was ground and washed multiple times with deionized water to remove residual sodium chloride. The mixture was then placed in a 65℃ drying oven and dried to constant weight. 2.8g of pale yellow Na-C3N4 powder was collected and sealed for later use.

[0024] (2) Preparation of Na-C3N4 / CeO2: Weigh 50 mg of Na-C3N4 powder (particle size approximately 62 μm), add 35 mL of deionized water, and sonicate in an ultrasonic instrument for 4 h to form a uniform suspension. Then weigh 25 mg of commercial CeO2 powder (particle size approximately 45 nm) and add it to the suspension. Stir magnetically at 200 r / min for 8 h at room temperature to ensure thorough mixing and contact. Transfer the mixed solution to a centrifuge tube and centrifuge at 8500 r / min for 30 min. Collect the wet material at the bottom and dry it in a 55℃ drying oven for 12 h. After grinding into a fine powder, the Na-C3N4 / CeO2 heterojunction material is obtained.

[0025] The prepared Na-C3N4 / CeO2 heterojunction material was subjected to HRTEM and EDS spectroscopy analysis, and the results are as follows: Figure 3 As shown, from Figure 3 The HRTEM images show that CeO2 nanoparticles are uniformly and well dispersed on the surface of Na-C3N4. CeO2 lattice fringes are clearly visible in the HRTEM images, while the Na-C3N4 lattice is difficult to find in the sample. A tight interface exists between CeO2 and Na-C3N4, forming a heterojunction. This is significant for suppressing the recombination of photogenerated carriers and the transfer of photogenerated electrons and holes, thus contributing to improved photocatalytic activity. Furthermore, EDS image analysis of Na-C3N4 / CeO2 revealed the presence of C, N, O, Na, and Ce elements in the sample, indicating the successful preparation of Na-C3N4 / CeO2.

[0026] Example 2: A method for preparing a sodium-doped carbon nitride cerium dioxide heterojunction photocatalytic material is as follows: (1) Preparation of Na-C3N4: Weigh 5g of melamine and 1g of sodium chloride, put them into a 50mL glass beaker, add 30mL of methanol, place the beaker on a magnetic stirrer, and stir at 250r / min for 7h to ensure that the materials are mixed evenly. After stirring, transfer to a drying oven and dry overnight at 80℃ until the methanol is completely evaporated to obtain a mixed solid.

[0027] The mixed solids were loaded into a covered crucible and placed in a muffle furnace. An air atmosphere and a heating program were set: the temperature was increased from room temperature to 500℃ at a rate of 1℃ / min and held for 10 hours to complete the thermal polymerization. After cooling, the mixture was ground and washed multiple times with deionized water to remove residual sodium chloride. Then, it was placed in a 65℃ drying oven to dry to constant weight. The pale yellow Na-C3N4 powder was collected and sealed for later use.

[0028] (2) Preparation of Na-C3N4 / CeO2: Weigh 25 mg of Na-C3N4 powder (particle size approximately 62 μm), add 35 mL of ethanol, and sonicate in an ultrasonic instrument for 4 h to form a uniform suspension. Then weigh 10 mg of commercial CeO2 powder (particle size approximately 45 nm) and add it to the suspension. Stir magnetically at 200 r / min for 8 h at room temperature to ensure thorough mixing and contact. Transfer the mixed solution to a centrifuge tube and centrifuge at 5000 r / min for 45 min. Collect the wet material at the bottom and dry it in a 55℃ drying oven for 12 h. After grinding into a fine powder, the Na-C3N4 / CeO2 heterojunction material is obtained.

[0029] Example 3: A method for preparing a sodium-doped carbon nitride cerium dioxide heterojunction photocatalytic material is as follows: (1) Preparation of Na-C3N4: Weigh 15g of melamine and 10g of sodium carbonate, put them into a 50mL glass beaker, add 30mL of isopropanol, place the beaker on a magnetic stirrer, and stir at 250r / min for 5h to ensure that the materials are mixed evenly. After stirring, transfer to a drying oven and dry overnight at 60℃ until the isopropanol is completely evaporated to obtain a mixed solid.

[0030] The mixed solids were loaded into a covered crucible and placed in a muffle furnace. The air atmosphere and heating program were set: 10℃ / min from room temperature to 600℃, and the temperature was held for 1 hour to complete the thermal polymerization. After cooling, the mixture was ground and washed multiple times with deionized water to remove residual sodium carbonate. Then it was placed in a 65℃ drying oven to dry to constant weight. The pale yellow Na-C3N4 powder was collected and sealed for later use.

[0031] (2) Preparation of Na-C3N4 / CeO2: Weigh 75 mg of Na-C3N4 powder (particle size approximately 62 μm), add 35 mL of methanol, and sonicate in an ultrasonic instrument for 6 h to form a uniform suspension. Then weigh 40 mg of commercial CeO2 powder (particle size approximately 45 nm) and add it to the suspension. Stir magnetically at 300 r / min for 10 h at room temperature to ensure thorough mixing and contact. Transfer the mixed solution to a centrifuge tube and centrifuge at 10000 r / min for 20 min. Collect the wet material at the bottom, dry it in a 55℃ drying oven for 12 h, and grind it into a fine powder to obtain the Na-C3N4 / CeO2 heterojunction material.

[0032] Example 4: Everything else is the same as in Example 1, except that: Replace melamine with urea and sodium chloride with sodium nitrate.

[0033] Example 5: Everything else is the same as in Example 1, except that: Replace melamine with dicyandiamide and sodium chloride with sodium sulfate.

[0034] Comparative Example 1: g-C3N4 was prepared as follows: Accurately weigh 10g of melamine, divide it into 4 equal portions, and place each portion into a lidded ceramic crucible. The crucibles are covered to reduce material volatilization during calcination. Place the crucibles in a muffle furnace, set the air atmosphere and heating program: 3.5℃ / min from room temperature to 550℃, hold at this temperature for 4 hours to complete the thermal polymerization. After the furnace has naturally cooled to room temperature, remove the yellow solid product, grind it into a fine powder using an agate mortar and pestle, and finally obtain 4.4g of g-C3N4 sample, which is sealed in a sample bottle for later use.

[0035] Comparative Example 2: Everything else is the same as in Example 1, except that: Replace the Na-C3N4 powder in step (2) with g-C3N4 powder to obtain g-C3N4 / CeO2.

[0036] The g-C3N4 prepared in Comparative Example 1, the g-C3N4 / CeO2 prepared in Comparative Example 2, and the Na-C3N4 prepared in Example 1 were compared. 4、 Na-C3N4 / CeO2 and CeO2 powder were used as test samples. The morphology of each sample was studied by field emission scanning electron microscopy (SEM) and field emission transmission electron microscopy (TEM), respectively. The results are as follows: like Figure 1 As shown, Figure 1 Image (a) is a SEM image of g-C3N4, image (b) is a SEM image of Na-C3N4, image (c) is a SEM image of CeO2, and image (d) is a SEM image of the Na-C3N4 / CeO2 sample. Figure 1 As can be seen, the bulk g-C3N4 exhibits an irregular, stacked layered structure. Na doping alters the morphology of g-C3N4 and etches the bulk g-C3N4 into smaller flakes, thus allowing the clear observation of the layered g-C3N4 structure. Figure 1 As shown in Figure (c), CeO2 appears as small, spherical particles that are clustered together. From... Figure 1 As observed in Figure (d), CeO2 nanoparticles are dispersed on the surface of Na-C3N4 without obvious agglomeration.

[0037] like Figure 2 As shown, Figure 2 Image (a) is a TEM image of the g-C3N4 sample, image (b) is a TEM image of the Na-C3N4 sample, image (c) is a TEM image of the CeO2 sample, and image (d) is a TEM image of the Na-C3N4 / CeO2 sample. Figure 2 As can be seen, g-C3N4 exhibits a relatively thick, stacked layer structure. After Na doping, g-C3N4 becomes very thin, and the layered structure of g-C3N4 can be clearly observed. Figure 2 As shown in Figure (c), CeO2 appears as small, spherical particles that are clustered together. From... Figure 2 As observed in Figure (d), CeO2 nanoparticles are dispersed on the surface of Na-C3N4 without obvious agglomeration.

[0038] The above test samples were subjected to XRD analysis, and the results are as follows: Depend on Figure 4 It is evident that g-C3N4 exhibits characteristic diffraction peaks at 12.9° (100) and 27.7° (002), corresponding to the periodic arrangement of triazine rings and the layered stacking of cyclic aromatic compounds, respectively. The peak intensity of the (002) crystal plane of Na-C3N4 is significantly reduced, indicating an increase in interlayer spacing, partial disruption of the graphite structure, and the formation of defects, which inhibits excessive crystal growth. The XRD pattern of g-C3N4 / CeO2 shows characteristic diffraction peaks of both components simultaneously. For the Na-C3N4 / CeO2 composite material, its spectrum also clearly shows the characteristic peaks corresponding to Na-C3N4 and CeO2. Notably, the intensity of the characteristic diffraction peak of Na-C3N4 / CeO2 at the (002) crystal plane is significantly reduced. This change indicates that the heterostructure has been successfully constructed, and the basic crystal structure of each component is maintained during the composite process.

[0039] The above test samples were subjected to infrared spectroscopy, and the results are as follows: like Figure 5As shown, the chemical structure of the photocatalyst was further investigated through analysis of these infrared spectra. Three main absorption regions were observed in g-C3N4, Na-C3N4, and Na-C3N4 / CeO2, in the 3000-3500 cm⁻¹ range. -1 The peak at 1200-1700 cm⁻¹ corresponds to the stretching vibrations of NH₄⁺ and OH⁻. -1 The absorption peak at 809 cm⁻¹ is attributed to the stretching vibration of the CN heterocycle. -1 The peak corresponds to the s-triazine ring vibration. Compared with pure g-C3N4, the Na-C3N4 sample shows a peak at 2176 cm⁻¹. -1 A distinct peak appeared at the point, which is attributed to the formation of C≡N. The infrared spectrum of the Na-C3N4 / CeO2 composite material shows the overlap of the CeO2 and Na-C3N4 spectra, indicating that the Na-C3N4 / CeO2 composite material was successfully prepared.

[0040] The applicant measured the steady-state fluorescence spectrum (PL) of the above samples, such as... Figure 6 As shown. By Figure 6 As can be seen, g-C3N4 exhibits the highest fluorescence intensity, which is due to the low carrier separation efficiency in pure carbon nitride. The emission peak is located at 460 nm, corresponding to the UV-Vis spectrum. After Na doping, a decrease in the photogenerated carrier separation (PL) intensity can be observed in g-C3N4, indicating that Na doping improves the photogenerated carrier separation efficiency. Upon recombination with CeO2, the PL intensity of g-C3N4 / CeO2 decreases, while the Na-C3N4 / CeO2 material exhibits the lowest PL peak intensity, indicating that its photogenerated carrier separation efficiency is the highest among all materials. This is consistent with the highest activity shown by Na-C3N4 / CeO2 in the performance test of photocatalytic oxidation desulfurization.

[0041] Photocatalytic oxidation desulfurization performance test Simulated fuel preparation: Weigh a certain amount of thiophene (TH) and add it to n-octane. Stir magnetically until completely dissolved. After adjusting the volume, prepare simulated fuel with a sulfur concentration of 200 ppm. Seal and store to prevent volatilization.

[0042] Photocatalytic reaction process: Measure 25 mL of simulated fuel and add it to 100 mL of the photocatalytic reactor. Then add 25 mg of Na-C3N4 / CeO2 material from Example 1, or Na-C3N4 material, or CeO2, or g-C3N4 material from Comparative Example 1. Seal the reactor with a quartz cap. Turn on a 300 W xenon lamp (the lamp source is 10 cm away from the reactor to ensure uniform light intensity), and keep air flowing in. Continue the reaction for 3 hours, taking samples periodically to monitor changes in thiophene concentration and calculating the desulfurization conversion rate.

[0043] The formula for calculating the desulfurization rate η (%) is: η = (1-Ct / C0) × 100% Where C0 is the initial sulfur content of the fuel, and Ct is the sulfur content of the fuel after degradation.

[0044] The application of different materials in the degradation of thiophene (TH) under visible light in an air atmosphere was studied, and the results are as follows: Figure 7 As shown, during the photocatalytic degradation process, after 3 h of reaction, the conversion rate of thiophene by g-C3N4 was 42.3%, and the conversion rate of thiophene by CeO2 was 23.2%. Na doping slightly improved the desulfurization performance of g-C3N4, as Na doping inhibited the recombination of generated carriers in g-C3N4, thus increasing its catalytic activity, but the improvement was extremely limited. The desulfurization rate of g-C3N4 / CeO2 was 56.7%. Although the formation of the heterojunction improved its oxidative desulfurization ability, the improvement was still relatively small compared to the desulfurization rate of g-C3N4 itself. Compared with g-C3N4, Na-C3N4, and g-C3N4 / CeO2, Na-C3N4 / CeO2 significantly improves the photocatalytic desulfurization rate, reaching 95.8%. This is mainly because CeO2 and Na-C3N4 not only form a heterojunction, but also achieve a synergistic effect through the specific microstructure of Na-C3N4 and the heterojunction structure, which is conducive to the efficient transfer of photogenerated charge carriers, thereby improving the PODS of thiophene-containing sulfur compounds in fuel.

Claims

1. A sodium-doped carbon nitride ceria heterojunction photocatalytic material, characterized in that, The heterojunction photocatalytic material comprises sodium-doped carbon nitride in sheet form and CeO2 spherical particles dispersed on the surface of the sodium-doped carbon nitride, and the sodium-doped carbon nitride forms a heterojunction with the CeO2.

2. The method for preparing the sodium-doped carbon nitride / cerium dioxide heterojunction photocatalytic material according to claim 1, characterized in that, The method comprises the following steps: (1) mixing an organic amine and a sodium source, calcining, and washing to obtain sodium-doped carbon nitride; (2) dispersing the sodium-doped carbon nitride and CeO2 in a liquid, mixing thoroughly to obtain a suspension; (3) centrifuging the suspension to obtain a precipitate, and drying to obtain the heterojunction photocatalytic material.

3. The method for preparing the sodium-doped carbon nitride / cerium dioxide heterojunction photocatalytic material according to claim 2, characterized in that, In step (1), the organic amine comprises at least one of melamine, urea, and dicyandiamide; and the sodium source comprises at least one of sodium chloride, sodium carbonate, sodium sulfate, and sodium nitrate.

4. The method for preparing the sodium-doped carbon nitride / cerium dioxide heterojunction photocatalytic material according to claim 2, characterized in that, In step (1), the mass ratio of the organic amine to the sodium source is 5-15:1-10.

5. The method of claim 2, wherein the sodium-doped carbon nitride / ceria heterojunction photocatalytic material is prepared by the following steps: (1) preparing a sodium-doped carbon nitride material; (2) preparing a ceria material; and (3) mixing the sodium-doped carbon nitride material and the ceria material. In step (1), the mixing method is as follows: dispersing the organic amine and the sodium source in an alcohol solvent, mixing to obtain a first mixture, and removing the alcohol solvent from the first mixture to obtain a mixed solid; the calcining condition is that the mixed solid of the organic amine and the sodium source is heated from room temperature to 500-600℃ at a rate of 1-10℃ / min, and the temperature is maintained for 1-10h; the washing method is that the calcination product is ground into powder, and water is used to wash the powder to remove residual sodium chloride, and the washed powder is dried to obtain the sodium-doped carbon nitride.

6. The method for preparing the sodium-doped carbon nitride / cerium dioxide heterojunction photocatalytic material according to claim 5, characterized in that, The alcohol solvent comprises at least one of methanol, ethanol, and propanol.

7. The method of claim 2, wherein the sodium-doped carbon nitride / ceria heterojunction photocatalytic material is prepared by the following steps: (1) preparing a sodium-doped carbon nitride material; (2) preparing a ceria material; and (3) mixing the sodium-doped carbon nitride material and the ceria material. In step (2), the mass ratio of the sodium-doped carbon nitride to the CeO2 is 25-75:10-40.

8. The method for preparing the sodium-doped carbon nitride / cerium dioxide heterojunction photocatalytic material according to claim 2, characterized in that, In step (2), the liquid is at least one of water, methanol, ethanol, and propanol.

9. Application of the heterojunction photocatalytic material prepared by the method of any one of claims 2-8 in photocatalytic degradation of sulfur-containing compounds in fuel oil.

10. Use according to claim 9, characterized in that, The sulfur-containing compounds comprise at least one of thiophene, thiophene derivatives, cyclic sulfide, disulfide, sulfide, mercaptan, and hydrogen sulfide.

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