A bio-oil carbon dot-supported g-C3N4 composite catalyst for photocatalytic hydrogen evolution, its preparation method and application

Abstract

This invention discloses a bio-oil carbon dot-supported g-C3N4 composite catalyst for photocatalytic hydrogen evolution, its preparation method, and its application. Using pine pyrolysis oil as raw material, DMF as both solvent and nitrogen source, and hydrogen peroxide aqueous solution as oxidant, nitrogen-doped highly crystalline carbon dots (PNCDs) were successfully prepared via a one-step hydrothermal method. Subsequently, the prepared PNCDs were loaded onto mesoporous g-C3N4 nanosheets using a high-temperature calcination method, constructing a PNCDs / g-C3N4 composite material with a three-dimensional hierarchical structure. This invention systematically studied the effect of PNCD loading on the photocatalytic hydrogen evolution performance of the composite material. The results show that loading a small amount of PNCDs onto the g-C3N4 surface can significantly improve its photocatalytic hydrogen production activity. This invention not only provides a new approach for the high-value utilization of bio-pyrolysis oil but also offers new ideas for developing efficient and low-cost photocatalytic hydrogen production materials.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic hydrogen production technology, and more specifically, to a bio-oil carbon point supported g-C3N4 composite catalyst for photocatalytic hydrogen evolution, its preparation method, and its application. Background Technology

[0002] With the acceleration of industrialization, the demand for traditional energy sources is constantly increasing, leading to a series of serious environmental problems. Therefore, developing and using green and clean energy has become an important strategy for environmental protection. Hydrogen energy, with its advantages of being clean and efficient, is considered a key to future energy transformation. Photocatalytic water splitting, with its characteristics of directly utilizing solar energy, requiring no additional power input, and having mild reaction conditions, is considered one of the most promising and attractive green hydrogen production strategies. g-C3N4, as a non-metallic photocatalyst, stands out due to its suitable band structure, excellent thermal stability, low cost, and environmental friendliness. However, g-C3N4 suffers from problems such as a narrow light absorption range and high photogenerated carrier recombination rate, which greatly limits its application in the field of photocatalytic hydrogen evolution. Therefore, researchers have adopted various modification strategies to improve the hydrogen evolution efficiency of photocatalysts. Among these, introducing a co-catalyst can enhance light absorption and suppress photogenerated electron-hole recombination.

[0003] Carbon dots are carbon nanomaterials smaller than 10 nm, composed of sp2 / sp3 hybridized carbon cores and surface functional groups. Compared with other carbon materials, carbon dots exhibit excellent photoluminescence properties and a wide light absorption range. Furthermore, carbon dots can serve as photogenerated electron storage devices, enabling spatial separation of photogenerated electrons and holes, thereby reducing the recombination rate of photogenerated carriers. Therefore, they are widely used to improve the hydrogen production efficiency of photocatalysts. Currently, although researchers have successfully prepared carbon dots using various carbon sources, such as small organic molecules, biomass, and waste, finding new low-cost carbon sources is crucial to advancing photocatalytic water production technology.

[0004] Bio-pyrolysis oil is a byproduct of the thermal decomposition of biomass under anaerobic or hypoxic conditions. It can be used directly as fuel in oil-fired boilers, turbines, and engines. However, due to its low calorific value, high oxygen content, and complex composition, bio-pyrolysis oil has limited its direct application. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned defects in the existing technology. This invention proposes an innovative application direction, providing a bio-oil carbon dot-supported g-C3N4 composite catalyst for photocatalytic hydrogen evolution, its preparation method, and its application. Using pine pyrolysis oil as raw material, DMF as solvent and nitrogen source, and hydrogen peroxide aqueous solution as oxidant, nitrogen-doped highly crystalline carbon dots (PNCDs) are prepared by a one-step hydrothermal method. Then, they are loaded onto mesoporous g-C3N4 nanosheets by high-temperature calcination to construct a three-dimensional hierarchical PNCDs / g-C3N4 composite material.

[0006] The inventors further investigated the effect of PNCDs content on the photocatalytic performance of the composite material. The results showed that loading a small amount of PNCDs on the surface of g-C3N4 can significantly improve its photocatalytic hydrogen evolution performance, opening up a new path for the efficient utilization of bio-pyrolysis oil and providing new ideas for the development of sustainable energy.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A method for preparing a bio-oil carbon dot-supported g-C3N4 composite catalyst for photocatalytic hydrogen evolution includes the following steps: (1) Pine biomass is thermally decomposed to obtain pine pyrolysis oil; (2) The pyrolysis oil of the pine wood is subjected to atmospheric distillation to obtain bio-oil residue; (3) The bio-oil residue is ultrasonicated and stirred with N,N-dimethylformamide (DMF) and hydrogen peroxide aqueous solution to form a mixed solution; (4) The mixed solution is subjected to hydrothermal synthesis, followed by cooling, centrifugation and filtration to obtain a carbon dot solution; (5) The carbon dot solution and urea are added to distilled water, ultrasonicated and stirred, and then calcined at high temperature. After washing and drying, the bio-oil carbon dot supported g-C3N4 composite catalyst is obtained.

[0009] Optionally, in step (1), the temperature of the thermal pyrolysis is 350~750℃; the time of the thermal pyrolysis is 35~60min; the heating rate of the thermal pyrolysis is 24℃ / min; and the atmosphere of the thermal pyrolysis is an inert atmosphere.

[0010] Optionally, in step (2), the temperature of atmospheric distillation is 200~300℃.

[0011] Optionally, in step (3), the mass-to-volume ratio of the bio-oil residue, the N,N-dimethylformamide, and the hydrogen peroxide aqueous solution is 0.5g:40ml:10ml. Optionally, in step (3), the concentration of the hydrogen peroxide aqueous solution is 30 wt%.

[0012] Optionally, in step (3), the ultrasound time is 2 hours; the stirring time is 30 minutes; and the stirring speed is 500 r / min.

[0013] Optionally, in step (4), the temperature of the hydrothermal synthesis is 200°C; the time of the hydrothermal synthesis is 8 hours; and the pressure of the hydrothermal synthesis is 2.5 MPa.

[0014] Optionally, in step (4), the centrifugation speed is 3000 r / min and the centrifugation time is 20 min.

[0015] Optionally, in step (4), the filtration is performed using a 22μm polytetrafluoroethylene filter.

[0016] Optionally, in step (5), the mass-to-volume ratio of the carbon dot solution, the urea, and the distilled water is 100μL~950μL:3g:20ml.

[0017] Optionally, in step (5), the ultrasound time is 1 hour; the stirring speed is 500 r / min; and the stirring time is 10 min.

[0018] Optionally, in step (5), the high-temperature calcination temperature is 540℃; the high-temperature calcination heating rate is 5℃ / min; and the high-temperature calcination time is 3h.

[0019] Optionally, in step (5), the crucible used for high-temperature calcination is an alumina crucible, and the alumina crucible is wrapped with aluminum foil before calcination.

[0020] Optionally, in step (5), the washing reagent used is anhydrous ethanol and distilled water.

[0021] Optionally, in step (5), the drying temperature is 70~105℃; the drying time is 4h~10h.

[0022] The present invention also discloses a bio-oil carbon dot supported g-C3N4 composite catalyst prepared by the preparation method described above.

[0023] The present invention also discloses a bio-oil carbon dot supported g-C3N4 composite catalyst prepared by the preparation method described above, or the application of the bio-oil carbon dot supported g-C3N4 composite catalyst described above in photocatalytic hydrogen production.

[0024] Implementing the embodiments of the present invention will have the following beneficial effects: This invention addresses the shortcomings of existing g-C3N4 photocatalysts, such as high photogenerated carrier recombination rate and narrow light absorption range, as well as the low calorific value, high oxygen content, and complex composition of bio-pyrolysis oil, and the need to explore low-cost carbon sources. It proposes a method for preparing high-performance composite photocatalysts using pine wood pyrolysis oil.

[0025] This invention utilizes pine pyrolysis oil as raw material, DMF as both solvent and nitrogen source, and hydrogen peroxide aqueous solution as oxidant to successfully prepare nitrogen-doped highly crystalline carbon dots (PNCDs) via a one-step hydrothermal method. Subsequently, the prepared PNCDs were loaded onto mesoporous g-C3N4 nanosheets using a high-temperature calcination method to construct a PNCDs / g-C3N4 composite material with a three-dimensional hierarchical structure. This invention systematically investigated the effect of PNCD loading on the photocatalytic hydrogen evolution performance of the composite material. The results show that loading a small amount of PNCDs onto the g-C3N4 surface can significantly improve its photocatalytic hydrogen evolution activity.

[0026] This invention not only provides a new approach for the high-value utilization of bio-pyrolysis oil, but also offers new ideas for developing efficient and low-cost photocatalytic hydrogen production materials. Attached Figure Description

[0027] Figure 1 This describes the preparation route of the PNCDs / g-C3N4 photocatalytic material in Example 1.

[0028] Figure 2 The images show the TEM and EDS-Mapping diagrams of the PNCDs / g-C3N4 photocatalyst material in Example 1.

[0029] Figure 3 The XRD patterns of g-C3N4 and PNCDs / g-C3N4 in Example 1 are shown.

[0030] Figure 4 The infrared spectra of g-C3N4 and PNCDs / g-C3N4 in Example 1 are shown.

[0031] Figure 5 The image shows the UV-Vis diffuse reflectance absorption spectra of g-C3N4 and PNCDs / g-C3N4 in Example 1.

[0032] Figure 6 XPS spectra of PNCDs, g-C3N4, and PNCDs / g-C3N4 in Example 1.

[0033] Figure 7 The hydrogen production performance of g-C3N4 and PNCDs / g-C3N4 photocatalysts in Example 1 is shown.

[0034] Figure 8The cyclic photocatalytic activity of the PNCDs / g-C3N4 photocatalytic material with high hydrogen production activity in Example 1 is shown.

[0035] Figure 9 The mechanism of the PNCDs / g-C3N4 photocatalytic material in Example 1. Detailed Implementation

[0036] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0037] In this invention, X-ray diffraction (XRD) spectroscopy is used to analyze the crystal structure and phase composition information of the material.

[0038] X-ray diffraction (XRD) spectroscopy is used to analyze the crystal structure and phase composition of materials.

[0039] Use transmission electron microscopy (TEM) to observe the morphology and structure of materials.

[0040] Infrared spectroscopy is used to analyze the structure and composition of materials.

[0041] X-ray photoelectron spectroscopy (XPS) was used to detect the chemical elemental composition and valence state of the material surface.

[0042] The optical properties of materials are tested using UV-vis diffuse reflection.

[0043] Example 1 The preparation method of the bio-oil carbon point supported g-C3N4 composite catalyst for photocatalytic hydrogen evolution in this embodiment includes the following steps: (1) Pine biomass was thermally decomposed in an inert atmosphere at a temperature of 500℃ for 50 min and a heating rate of 24℃ / min to obtain pine pyrolysis oil.

[0044] (2) The pyrolysis oil of pine wood is distilled at atmospheric pressure at a temperature of 250°C to obtain bio-oil residue.

[0045] (3) The bio-oil residue, DMF and hydrogen peroxide aqueous solution (concentration of 30wt%) were ultrasonicated for 2 hours and stirred for 30 minutes at a mass-volume ratio of 0.5g:40ml:10ml to form a mixed solution.

[0046] (4) The mixed solution was subjected to hydrothermal synthesis at a temperature of 200℃ for 8 hours and a pressure of 2.5MPa. After cooling and centrifugation (3000r / min, 20min), the carbon dot solution was obtained by filtration through a 22μm polytetrafluoroethylene filter.

[0047] (5) Add carbon dot solution and urea to distilled water (the mass-volume ratio of carbon dot solution, urea and distilled water is 350 μL: 3 g: 20 ml), sonicate for 1 h and stir at a stirring speed of 500 r / min for 10 min. Then, calcine at 540 °C for 3 h at a heating rate of 5 °C / min. After washing and drying (70 °C; 6 h), the bio-oil carbon dot supported g-C3N4 composite catalyst is obtained.

[0048] The photocatalytic hydrogen production performance of the PNCDs / g-C3N4 photocatalytic material prepared in Example 1 was verified by evaluating the amount of hydrogen produced by water decomposition under visible light.

[0049] 10.0 mg of the composite catalyst prepared in Example 1 was accurately weighed and dispersed in 100 mL of triethanolamine aqueous solution (10 vol%). The mixture was stirred with a magnetic stirrer for 30 min to form a homogeneous suspension. 1 mL of chloroplatinic acid solution (0.300 mol / L) was introduced into the system using a microsyringe, and the reaction mixture was then transferred to a quartz photocatalytic reactor. In-situ photodeposition was then performed using a 300 W xenon lamp equipped with a UV cutoff filter (λ > 420 nm). The loading of Pt nanoparticles was precisely controlled at 3.0 wt% by adjusting the irradiation time. Before the experiment, the system was continuously purged with high-purity nitrogen (99.999%) at a flow rate of 50 mL / min for 30 min to establish an anaerobic environment, and magnetic stirring (800 rpm) was maintained to ensure system homogeneity. During the photocatalytic reaction, 1 mL of headspace gas was collected every 60 min using a gas-tight syringe and injected into a gas chromatography system equipped with a TCD detector (5A molecular sieve column, Ar carrier gas, column temperature 80 °C). Hydrogen concentration was quantitatively analyzed using the external standard method, and the hydrogen production rate was accurately calculated by combining this with the reactor headspace volume. During the experiment, a circulating water pump was used to maintain the reactor temperature at 5°C.

[0050] Figure 1 This describes the preparation process of the PNCDs / g-C3N4 photocatalytic material in this embodiment.

[0051] Figure 2 This is a TEM image of the PNCDs / g-C3N4 photocatalyst material in this embodiment. Figure 2 In the model, pure g-C3N4 exhibits a typical layered stacked structure with relatively loose layers and a relatively flat surface. After loading PNCDs, the morphology of the PNCDs / g-C3N4 did not change significantly. These transmission electron microscopy images confirm that PNCDs were successfully loaded and bonded to the surface of the g-C3N4 nanosheets, and that the lattice spacing of the PNCDs was 0.23 nm.

[0052] Figure 3The XRD patterns of g-C3N4 and PNCDs / g-C3N4 in this embodiment are shown. The peaks at 13.0° and 27.3° correspond to the (100) and (002) crystal planes of g-C3N4, respectively, representing the planar structure of the triazine unit and the interlayer stacking of the conjugated aromatic structure. Notably, after adding PNCDs, the intensity of the sharp peak at 21.7° of g-C3N4 drops sharply, indicating that PNCDs successfully load g-C3N4 into its structure without changing the graphitic structure of g-C3N4.

[0053] Figure 4 The images show the infrared spectra of g-C3N4 and PNCDs / g-C3N4 in this embodiment. Clearly, the characteristic peaks of PNCDs / g-C3N4 remain relatively consistent compared to pure g-C3N4. The characteristic stretching peaks are mainly distributed in three regions: 810 cm⁻¹... - ¹、1200-1700 cm - ¹、3000-3500 cm - ¹. 3000-3500 cm - The broad vibrational band at ¹ is attributed to NH, residual amino, and OH groups adsorbed on the g-C3N4 surface. The peak intensity decreases significantly with varying carbon dot content. (1100-1700 cm⁻¹) - ¹ Multiple strong vibrational peaks within this range originate from the characteristic stretching vibrations of the C–N heterocyclic structure. Furthermore, at 810 cm⁻¹… - The sharp peak at ¹ corresponds to the stretching vibration of the triazine ring.

[0054] Figure 5 The images show the UV-Vis diffuse reflectance absorption spectra of the g-C3N4 and PNCDs / g-C3N4 photocatalytic materials in this embodiment. Compared to pure g-C3N4, all samples modified with the additives showed enhanced light absorption in the visible region. Furthermore, the figures show a distinct absorption peak around 370 nm for both g-C3N4 and PNCDs / g-C3N4, attributed to the local surface plasmon resonance (LSPR) effect of the PNCD nanoparticles, indicating successful deposition of the PNCD nanoparticles.

[0055] Figure 6 The figures show the high-resolution XPS spectra of PNCDs, g-C3N4, and PNCDs / g-C3N4 in this embodiment. As can be seen from the figures, nitrogen doping was successfully achieved with PNCDs, and both g-C3N4 and PNCDs / g-C3N4 XPS spectra show obvious C 1s (~288 eV) and N 1s (~398 eV) characteristic peaks, confirming that the composite material is mainly composed of carbon and nitrogen. This confirms that CDs were successfully integrated into the g-C3N4 nanosheets.

[0056] Figure 7 The image shows the photocatalytic hydrogen production performance of g-C3N4 and PNCDs / g-C3N4 photocatalytic materials in this embodiment. It can be seen that the photocatalytic hydrogen production performance of pure g-C3N4 is 0.4 mmol / h. -1 g -1 When PNCDs are deposited on g-C3N4, the photocatalytic hydrogen production performance of the PNCDs / g-C3N4 photocatalytic material is further significantly enhanced, reaching 2.43 mmol / h. -1 g -1 .

[0057] Figure 8 This section describes the cycle stability of the hydrogen production performance of the high-hydrogen-yielding PNCDs / g-C3N4 photocatalyst material in this embodiment. Figure 8 As can be seen, after four photocatalytic hydrogen production cycle experiments, the photocatalytic hydrogen production activity of the PNCDs / g-C3N4 photocatalyst did not decrease significantly, indicating that the highly active PNCDs / g-C3N4 material prepared in this invention has good cycle stability in photocatalytic hydrogen production applications.

[0058] Figure 9 The mechanism of the PNCDs / g-C3N4 photocatalytic material in Example 1 is illustrated. The photocatalytic hydrogen production process comprises three consecutive steps: photoexcitation to generate electron-hole pairs, electron migration, and surface catalytic reaction. Regarding light absorption, carbon dot (PNCDs) modification narrows the band gap (Eg) of PNCDs / g-C3N4, and the band gap determines the minimum energy threshold for photon absorption. The narrowed band gap allows the material to absorb low-energy photons corresponding to longer wavelengths. Furthermore, by introducing intermediate energy levels, carbon dots enable electrons to transition from the valence band to these intergrowth states, resulting in a redshift of the absorption edge, thereby extending the visible light utilization range to the longer wavelength region (≥500 nm). In terms of carrier separation, the ultrathin structure of g-C3N4 nanosheets significantly shortens the migration distance of conduction band electrons to the surface, effectively suppressing bulk recombination. Simultaneously, carbon dots anchored to the g-C3N4 surface act as electron traps, effectively capturing and directionally transporting conduction band electrons from the g-C3N4 nanosheets through their specific electron affinity, achieving rapid spatial separation of electron-hole pairs. The synergistic effect of band alignment and interface coupling in the heterojunction optimizes the separation and utilization efficiency of photogenerated carriers, ultimately significantly enhancing the photocatalytic hydrogen evolution activity of the composite system. During the photocatalytic reaction, Pt acts as a co-catalyst for H2O. + Reduction provides the active site, while triethanolamine acts as a sacrificial electron donor for holes. In the photocatalytic reaction, Pt acts as a co-catalyst (promoter) for H... + Reduction provides the active site, while triethanolamine (TEOA) is a sacrificial electron donor used to capture holes.

[0059] Example 2 The difference between this embodiment and embodiment 1 is that in step (5), the amount of carbon dot solution added is 100 μL, and the amount of urea and distilled water added is the same as in embodiment 1.

[0060] Example 3 The difference between this embodiment and embodiment 1 is that in step (5), the amount of carbon dot solution added is 200 μL, and the amount of urea and distilled water added is the same as in embodiment 1.

[0061] Example 4 The difference between this embodiment and embodiment 1 is that in step (5), the amount of carbon dot solution added is 500 μL, and the amount of urea and distilled water added is the same as in embodiment 1.

[0062] Example 5 The difference between this embodiment and embodiment 1 is that in step (5), the amount of carbon dot solution added is 650 μL, and the amount of urea and distilled water added is the same as in embodiment 1.

[0063] Example 6 The difference between this embodiment and embodiment 1 is that in step (5), the amount of carbon dot solution added is 800 μL, and the amount of urea and distilled water added is the same as in embodiment 1.

[0064] Example 7 The difference between this embodiment and embodiment 1 is that in step (5), the amount of carbon dot solution added is 950 μL, and the amount of urea and distilled water added is the same as in embodiment 1.

[0065] The hydrogen production performance of the PNCDs / g-C3N4 photocatalyst materials prepared in Examples 2-7 was tested. Combined with the test results of Example 1, it was found that when the PNCDs addition amounts were 100, 200, 350, 500, 650, 800, and 950 μL, the hydrogen production performance of the PNCDs / g-C3N4 photocatalyst was 1.63, 1.41, 2.43, 1.35, 0.8, 1.17, and 1.17 mmol h⁻¹, respectively. -1 g -1 The results show that the photocatalytic hydrogen production performance of PNCDs / g-C3N4 is higher than that of g-C3N4, and its performance first increases and then decreases with increasing PNCDs concentration. Therefore, the optimal PNCDs addition amount is 350 μL in the preparation process of PNCDs / g-C3N4 photocatalyst.

[0066] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a bio-oil carbon dot-supported g-C3N4 composite catalyst for photocatalytic hydrogen evolution, characterized in that, Includes the following steps: (1) Pine biomass is thermally decomposed to obtain pine pyrolysis oil; (2) The pyrolysis oil of the pine wood is subjected to atmospheric distillation to obtain bio-oil residue; (3) The bio-oil residue is ultrasonicated and stirred with N,N-dimethylformamide and hydrogen peroxide aqueous solution to form a mixed solution; (4) The mixed solution is subjected to hydrothermal synthesis, followed by cooling, centrifugation and filtration to obtain a carbon dot solution; (5) The carbon dot solution and urea are added to distilled water, ultrasonicated and stirred, and then calcined at high temperature. After washing and drying, the bio-oil carbon dot supported g-C3N4 composite catalyst is obtained.

2. The method for preparing the bio-oil carbon dot-supported g-C3N4 composite catalyst for photocatalytic hydrogen evolution according to claim 1, characterized in that, In step (1), the temperature of the thermal pyrolysis is 350~750℃; the time of the thermal pyrolysis is 35~60min; the heating rate of the thermal pyrolysis is 24℃ / min; and the atmosphere of the thermal pyrolysis is an inert atmosphere.

3. The method for preparing the bio-oil carbon dot-supported g-C3N4 composite catalyst for photocatalytic hydrogen evolution according to claim 1, characterized in that, In step (2), the temperature of atmospheric distillation is 200~300℃.

4. The method for preparing the bio-oil carbon dot-supported g-C3N4 composite catalyst for photocatalytic hydrogen evolution according to claim 1, characterized in that, In step (3), the mass-to-volume ratio of the bio-oil residue, the N,N-dimethylformamide, and the hydrogen peroxide aqueous solution is 0.5g:40ml:10ml; In step (3), the concentration of the hydrogen peroxide aqueous solution is 30 wt%; In step (3), the ultrasound time is 2 hours; the stirring time is 30 minutes; and the stirring speed is 500 r / min.

5. The method for preparing the bio-oil carbon dot-supported g-C3N4 composite catalyst for photocatalytic hydrogen evolution according to claim 1, characterized in that, In step (4), the temperature of the hydrothermal synthesis is 200℃; the time of the hydrothermal synthesis is 8h; and the pressure of the hydrothermal synthesis is 2.5MPa. In step (4), the centrifugation speed is 3000 r / min and the centrifugation time is 20 min; In step (4), the filtration is performed using a 22μm polytetrafluoroethylene filter.

6. The method for preparing the bio-oil carbon dot-supported g-C3N4 composite catalyst for photocatalytic hydrogen evolution according to claim 1, characterized in that, In step (5), the mass-to-volume ratio of the carbon dot solution, the urea, and the distilled water is 100 μL~950 μL: 3 g: 20 ml; In step (5), the ultrasound time is 1 hour; the stirring speed is 500 r / min; and the stirring time is 10 minutes. In step (5), the temperature of the high-temperature calcination is 540℃; the heating rate of the high-temperature calcination is 5℃ / min; and the time of the high-temperature calcination is 3h. In step (5), the washing reagent used is anhydrous ethanol and distilled water used alternately for washing; In step (5), the drying temperature is 70℃~105℃; the drying time is 4h~10h.

7. A bio-oil carbon dot-supported g-C3N4 composite catalyst prepared by the preparation method according to any one of claims 1-6.

8. The application of a bio-oil carbon dot-supported g-C3N4 composite catalyst prepared by any one of claims 1-6, or the bio-oil carbon dot-supported g-C3N4 composite catalyst as described in claim 7, in photocatalytic hydrogen production.

Images