Preparation method of amido-modified Ru quantum dot-loaded mixed crystal C3N5 catalyst

Abstract

The invention discloses a preparation method of an amido modified and Ru quantum dot loaded mixed crystal C3N5 catalyst, and the preparation method comprises the following steps: by taking 3-amino-1, 2, 4-triazole, namely 3-AT, as a raw material, preparing a body C3N5 by adopting a pyrolysis method; the method comprises the following steps: calcining a body C3N5 at a high temperature in a nitrogen atmosphere to obtain a mixed crystal C3N5 containing amorphous C3N5, namely MC3N5; according to the method, RuCl3. 3H2O and MC3N5 are taken as raw materials, deionized water is taken as a solvent, the raw materials are violently stirred and fully impregnated, then centrifugal drying is carried out, the product is placed in an H2 / Ar mixed atmosphere to be calcined, and Ru quantum dot loaded MC3N5, namely RQ / MC3N5, is obtained; the preparation method comprises the following steps: by taking L-ascorbic acid, namely VC and RQ / MC3N5 as raw materials and deionized water as a solvent, preparing a VC-RQ / MC3N5 catalyst by adopting a solvothermal method; the preparation process is simple, the production cost is low, and the prepared VC-RQ / MC3N5 catalyst greatly improves the capability and stability of anchoring Ru quantum dots by the substrate C3N5; by introducing VC modification and quantum dot anchoring, the light absorption capacity, the surface adsorption capacity and the carrier separation and migration capacity of the catalyst can be effectively improved, so that the catalytic performance of the material is improved.

Description

Technical Field

[0001] This invention relates to the fields of environmental pollution control and production capacity technology, and in particular to a method for preparing a mixed-crystal C3N5 catalyst with amide group modification and Ru quantum dot support. Background Technology

[0002] Nitrogen-rich carbonitrides (C3N5) have attracted much attention as a novel photocatalytic semiconductor material due to their simple synthesis process, high cost-effectiveness, and environmental friendliness. However, like most semiconductor materials, C3N5 also faces challenges such as high carrier recombination efficiency and insufficient catalytic active sites. These defects fundamentally limit the quantum efficiency and interfacial reaction kinetics of C3N5, posing a significant challenge to achieving excellent photocatalytic performance under sunlight irradiation.

[0003] Therefore, loading metal quantum dots onto C3N5 is a simple and effective solution to address the aforementioned shortcomings of C3N5. Ruthenium (Ru) exhibits excellent hydrogen adsorption energy due to its high d-band center. Furthermore, compared to the high cost of platinum (Pt), Ru's low cost (approximately 33% of Pt's price) makes it a preferred choice for loading noble metal quantum dots; and Ru's broad spectral capture range and strong affinity for nitrogen further make it a high-quality noble metal for loading onto a C3N5 substrate. In addition, to address the uneven distribution, agglomeration, and deactivation of Ru quantum dots during loading and catalysis, introducing amorphous C3N5 rich in defects and coordination unsaturated sites can effectively disperse Ru quantum dots and uniformly anchor them on the C3N5 substrate. Simultaneously, this amorphous structure can selectively capture photogenerated holes, preventing them from flowing back to the bulk phase; while the internally retained crystalline C3N5 effectively maintains the stability of the overall structure, avoiding carrier transport blockage caused by complete amorphization.

[0004] Surface modification of C3N5 is also an effective strategy to enhance its catalytic activity. The amide group, acting as an electron-donating group, can rapidly extract photogenerated holes from the valence band of C3N5 and enrich them on the surface, thereby achieving spatial separation of electron-hole pairs and providing active sites for related oxidation reactions. Since the C3N5 surface is rich in amino (-NH2) and imino (=NH) active sites, the lactone ring of VC readily undergoes a ring-opening reaction under hydrothermal conditions to generate a carboxyl group (-COOH). Subsequently, -COOH undergoes a condensation reaction with -NH2 on C3N5 to form an amide covalent bond (-CONH-), thus anchoring the amide group to the MC3N5 surface. This amide group, acting as an electron donor, can rapidly extract holes and enrich them on the surface, promoting spatial separation of photogenerated electrons and holes in the catalyst. It can also effectively enhance the catalyst's light absorption and surface adsorption capacity, thereby further improving the catalytic performance of the material. However, there are currently no reports on the preparation of mixed-crystal C3N5 catalysts VC-RQ / MC3N5 with amide group modification rich in hydroxyl carbon chains and Ru quantum dot support using methods such as solvothermal and impregnation reduction. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems existing in the prior art and to provide a method for preparing a mixed-crystal C3N5 catalyst with amide group modification and Ru quantum dot support.

[0006] To achieve the above objectives, the technical solution provided by this invention is: a method for preparing an amide-modified Ru quantum dot-supported mixed-crystalline C3N5 catalyst, wherein the preparation method employs pyrolysis, impregnation reduction, and other methods to prepare amide-modified Ru quantum dot-supported mixed-crystalline C3N5, i.e., VC-RQ / MC3N5 catalyst; the preparation method involves fully impregnating amorphous C3N5 rich in numerous defects and coordination unsaturated sites in a RuCl3·3H2O solution, and then calcining the centrifuged and dried precursor under an H2 / Ar mixed atmosphere to obtain RQ / MC3N5; subsequently, a synergistic solvothermal method is used to induce a ring-opening reaction of the lactone ring in VC to generate a carboxyl group, which then undergoes a condensation reaction with the amino group on MC3N5, to prepare a unique hydroxyl-rich carbon chain amide-modified Ru quantum dot-supported mixed-crystalline C3N5 catalyst, i.e., VC-RQ / MC3N5 catalyst; the preparation method specifically includes the following steps: A certain amount of 3-AT was added to a covered Al2O3 crucible, then placed in a muffle furnace and pyrolyzed at a certain temperature for 1-6 h. After grinding, bulk C3N was obtained. 5， 3-AT is 3-amino-1,2,4-triazole; A certain amount of the bulk C3N5 obtained in step (1) is placed in an N2 atmosphere, heated to a certain temperature and held for 1-6 h, and then cooled to room temperature in the furnace to obtain mixed crystal C3N5 containing amorphous C3N5, namely MC3N5. Take a certain amount of RuCl3·3H2O and dissolve it in an appropriate amount of deionized water. After stirring until completely dissolved, add a certain amount of MC3N5 obtained in step (2) and disperse it in it. After stirring vigorously and soaking for 1-36 h, centrifuge and take the precipitate to dry under vacuum to obtain the Ru quantum dot loaded MC3N5 precursor, i.e. RQ / MC3N5 precursor. A certain amount of the RQ / MC3N5 precursor obtained in step (3) was added into a ceramic boat, and then heated to a certain temperature under a H2 / Ar mixed atmosphere and held for 30-360 min to obtain RQ / MC3N5. Take a certain amount of VC and dissolve it in an appropriate amount of deionized water. VC is L-ascorbic acid. After stirring until completely dissolved, add a certain amount of RQ / MC3N5 obtained in step (4) and disperse it in it. Stir thoroughly for 1-360 min to form a uniformly mixed suspension. The suspension obtained in step (5) was transferred into a solvothermal reactor and reacted at a certain temperature for 1-24 h. The resulting product was centrifuged, washed, and vacuum dried to obtain the VC-RQ / MC3N5 catalyst.

[0007] Preferably, the mass of 3-AT used in step (1) is 0.1-10 g, and the pyrolysis temperature is 350-650 ℃.

[0008] Preferably, the mass of the C3N5 used in step (2) is 0.1-10 g, and the heating temperature is 500-800 ℃.

[0009] Preferably, in step (3), the mass of RuCl3·3H2O used is 0.01-10 g, the volume of deionized water is 1-1000 mL, the mass of MC3N5 is 0.1-10 g, the vacuum drying temperature is 30-100 ℃, and the time is 1-48 h.

[0010] Preferably, the mass of the RQ / MC3N5 precursor used in step (4) is 0.01-10 g, and the heating temperature is 100-800℃.

[0011] Preferably, the mass of VC used in step (5) is 0.01-10 g, the volume of deionized water is 1-1000 mL, and the mass of RQ / MC3N5 is 0.01-10 g.

[0012] Preferably, in step (6), the reaction temperature of the solvothermal reactor is 80-350 ℃, the vacuum drying temperature is 30-100 ℃, and the time is 1-48 h.

[0013] Beneficial effects of this invention: This invention employs solvothermal and impregnation-reduction methods to achieve the synergistic loading of Ru quantum dots on mixed-crystalline C3N5 by modifying amide groups. The preparation process is simple and cost-effective. The prepared VC-RQ / MC3N5 catalyst utilizes the abundant defects and coordination unsaturated sites of the amorphous C3N5 surface, significantly improving the loading and stability of Ru quantum dots anchored in the C3N5 substrate. Simultaneously, this amorphous structure can selectively trap photogenerated holes, preventing them from flowing back into the bulk phase; while the retained crystalline C3N5 effectively maintains the overall structural stability. Qualitatively, this invention introduces a novel VC modification, using a solvothermal method to induce a ring-opening reaction of the lactone ring in VC to generate a carboxyl group, which then undergoes a condensation reaction with the amino group on MC3N5 to form an amide covalent bond. This results in a unique amide group rich in hydroxyl carbon chains modifying the surface of MC3N5. This amide group acts as an electron donor, rapidly extracting holes and accumulating them on the surface, promoting the spatial separation and migration of photogenerated electrons and holes in the catalyst. It also effectively enhances the light absorption capacity and surface adsorption capacity of the catalyst, thereby further improving the catalytic performance of the material.

[0014] The VC-RQ / MC3N5 catalyst prepared by this invention has the advantages of strong visible light response, stable structure, excellent surface adsorption capacity, high carrier separation efficiency and abundant active sites. It is expected to be applied in the fields of photocatalytic water splitting to produce hydrogen, pollutant degradation and CO2 reduction. Attached Figure Description

[0015] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention.

[0016] Figure 1 This is a flowchart of the sample preparation process in the preparation method of a mixed-crystal C3N5 catalyst with amide group modification and Ru quantum dot support according to the present invention.

[0017] Figure 2 This is a transmission electron microscope image of VC-RQ / MC3N5 prepared in the preparation method of amide-modified synergistic Ru quantum dot supported mixed crystal C3N5 catalyst of the present invention; wherein, the dashed circle in Figure b represents Ru quantum dots, and the inset is Ru lattice fringes.

[0018] Figure 3These are the UV-Vis diffuse reflectance and fluorescence spectra of a sample from the preparation method of an amide-modified, Ru-quantum-dot-supported mixed-crystalline C3N5 catalyst according to the present invention; wherein, Figure 3 a is the ultraviolet-visible diffuse reflectance spectrum. Figure 3 b is the fluorescence spectrum.

[0019] Figure 4 This is a graph showing the photocatalytic hydrogen production performance of a sample prepared using the method for preparing an amide-modified, Ru quantum dot-supported mixed-crystal C3N5 catalyst according to the present invention; wherein, Figure 4 a is a comparison graph of photocatalytic hydrogen production rates of the samples. Figure 4 b is a comparison of the photocatalytic hydrogen evolution efficiency of the samples under 5 rounds of 15-hour cycle tests. Detailed Implementation

[0020] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention. Example 1

[0021] A method for preparing a mixed-crystal C3N5 catalyst with amide group modification and Ru quantum dot support.

[0022] (1) 1 g of 3-AT was added to a lidded Al2O3 crucible, and then placed in a muffle furnace and pyrolyzed at 500 °C for 2 h. After grinding, bulk C3N5 was obtained. Then, 1 g of bulk C3N5 was placed in a N2 atmosphere, heated to 620 °C and held for 1 h. After cooling to room temperature with the furnace, MC3N5 was obtained. (2) Dissolve 0.01 g RuCl3·3H2O in 100 mL of deionized water. After stirring until completely dissolved, add 0.1 g MC3N5 and disperse it in the solution. Stir vigorously and soak for 12 h. Centrifuge and take the precipitate to be vacuum dried at 60 ℃ for 12 h to obtain RQ / MC3N5 precursor. Then, add the precursor to a ceramic boat and heat it to 300 ℃ under H2 / Ar mixed atmosphere and keep it for 120 min to obtain RQ / MC3N5. (3) Dissolve 0.02 g of VC in 100 mL of deionized water. After stirring until completely dissolved, add 0.1 g of RQ / MC3N5 and disperse it in the solution. Stir well for 60 min to form a uniform suspension. Then transfer the suspension into a solvothermal reactor and react at 180 °C for 12 h. The precipitate is washed three times by alternating centrifugation with deionized water and anhydrous ethanol, and then dried under vacuum at 60 °C for 12 h to obtain the VC-RQ / MC3N5 catalyst. Example 2

[0023] A method for preparing a mixed-crystal C3N5 catalyst with amide group modification and Ru quantum dot support.

[0024] (1) 2 g of 3-AT was added to a lidded Al2O3 crucible, and then placed in a muffle furnace and pyrolyzed at 520 °C for 3 h. After grinding, bulk C3N5 was obtained. Then, 2 g of bulk C3N5 was placed in a N2 atmosphere, heated to 640 °C and held for 2 h. After cooling to room temperature with the furnace, MC3N5 was obtained. (2) Dissolve 0.05 g RuCl3·3H2O in 200 mL of deionized water. After stirring until completely dissolved, add 1 g of MC3N5 and disperse it in the solution. Stir vigorously and soak for 18 h. Centrifuge and take the precipitate. Place it in a vacuum dryer at 70 °C for 10 h to obtain the RQ / MC3N5 precursor. Then, add the precursor to a ceramic boat and heat it to 350 °C in a mixed atmosphere of H2 / Ar for 60 min to obtain RQ / MC3N5. (3) Dissolve 0.1 g of VC in 200 mL of deionized water. After stirring until completely dissolved, add 1 g of RQ / MC3N5 and disperse it in the solution. Stir thoroughly for 90 min to form a uniform suspension. Then transfer the suspension into a solvothermal reactor and react at 160 °C for 16 h. The precipitate is washed three times by alternating centrifugation with deionized water and anhydrous ethanol, and then dried under vacuum at 70 °C for 10 h to obtain the VC-RQ / MC3N5 catalyst. Example 3

[0025] A method for preparing a mixed-crystal C3N5 catalyst with amide group modification and Ru quantum dot support.

[0026] (1) 3 g of 3-AT was added to a lidded Al2O3 crucible, and then placed in a muffle furnace and pyrolyzed at 550 °C for 4 h. After grinding, bulk C3N5 was obtained. Then, 3 g of bulk C3N5 was placed in a N2 atmosphere, heated to 660 °C and held for 3 h. After cooling to room temperature in the furnace, MC3N5 was obtained. (2) Dissolve 0.1 g RuCl3·3H2O in 500 mL of deionized water. After stirring until completely dissolved, add 2 g MC3N5 and disperse it in the solution. Stir vigorously and soak for 24 h. Centrifuge and take the precipitate to be vacuum dried at 80 °C for 8 h to obtain RQ / MC3N5 precursor. Then, add the precursor to a ceramic boat and heat it to 400 °C under a H2 / Ar mixed atmosphere and keep it for 180 min to obtain RQ / MC3N5. (3) Dissolve 0.1 g of VC in 500 mL of deionized water. After stirring until completely dissolved, add 2 g of RQ / MC3N5 and disperse it in the solution. Stir thoroughly for 180 min to form a uniform suspension. Then transfer the suspension into a solvothermal reactor and react at 200 °C for 8 h. The precipitate is washed three times by alternating centrifugation with deionized water and anhydrous ethanol, and then dried under vacuum at 80 °C for 8 h to obtain the VC-RQ / MC3N5 catalyst. Example 4

[0027] Photocatalytic performance testing was conducted at room temperature in a top-irradiated Pyrex reactor connected to a glass-sealed gas circulation system. First, 50 mg of VC-RQ / MC3N5 catalyst powder was dispersed in 100 mL of triethanolamine (10% v / v) solution. The reactor was then fixed to an automated online vacuum photocatalytic system. A vacuum pump was used to evacuate the system, and multiple gas purging operations were performed (alternating between vacuum evacuation and carrier gas filling) to ensure the reaction system was in an anaerobic state, while circulating water cooling (6°C) was initiated. Subsequently, photocatalytic hydrogen production experiments were conducted under a 300 W visible light source, and the amount of H2 produced was measured every half hour using gas chromatography.

[0028] Without causing conflict, those skilled in the art can freely combine and use the above-mentioned additional technical features.

[0029] The above description is only a preferred embodiment of the present invention. Any technical solution that achieves the purpose of the present invention by essentially the same means is within the protection scope of the present invention.

Claims

1. A method for preparing an amide-modified, Ru quantum dot-supported mixed-crystal C3N5 catalyst, characterized in that: The preparation method involves fully impregnating amorphous C3N5 rich in defects and coordination unsaturated sites in a RuCl3·3H2O solution, followed by calcination of the centrifuged and dried precursor under an H2 / Ar mixed atmosphere to obtain RQ / MC3N5. Subsequently, a synergistic solvothermal method is used to induce a ring-opening reaction of the lactone ring in VC to generate a carboxyl group, which then undergoes a condensation reaction with the amino group on MC3N5, thus preparing a unique mixed-crystal C3N5 catalyst rich in hydroxyl carbon chain amide groups and synergistically supported by Ru quantum dots, namely the VC-RQ / MC3N5 catalyst. The specific preparation method includes the following steps: A certain amount of 3-AT was added to a covered Al2O3 crucible, then placed in a muffle furnace and pyrolyzed at a certain temperature for 1-6 hours. After grinding, bulk C3N was obtained. 5， 3-AT is 3-amino-1,2,4-triazole; A certain amount of the bulk C3N5 obtained in step (1) is placed in an N2 atmosphere, heated to a certain temperature and held for 1-6 h, and then cooled to room temperature in the furnace to obtain mixed crystal C3N5 containing amorphous C3N5, namely MC3N5. Take a certain amount of RuCl3·3H2O and dissolve it in an appropriate amount of deionized water. After stirring until completely dissolved, add a certain amount of MC3N5 obtained in step (2) and disperse it in it. After stirring vigorously and soaking for 1-36 h, centrifuge and take the precipitate to dry under vacuum to obtain the Ru quantum dot loaded MC3N5 precursor, i.e. RQ / MC3N5 precursor. A certain amount of the RQ / MC3N5 precursor obtained in step (3) was added into a ceramic boat, and then heated to a certain temperature under a H2 / Ar mixed atmosphere and held for 30-360 min to obtain RQ / MC3N5. Take a certain amount of VC and dissolve it in an appropriate amount of deionized water. VC is L-ascorbic acid. After stirring until completely dissolved, add a certain amount of RQ / MC3N5 obtained in step (4) and disperse it in it. Stir thoroughly for 1-360 min to form a uniformly mixed suspension. The suspension obtained in step (5) was transferred into a solvothermal reactor and reacted at a certain temperature for 1-24 h. The resulting product was centrifuged, washed, and vacuum dried to obtain the VC-RQ / MC3N5 catalyst.

2. The method for preparing an amide-modified, Ru quantum dot-supported mixed-crystal C3N5 catalyst according to claim 1, characterized in that: The mass of 3-AT used in step (1) is 0.1-10 g, and the pyrolysis temperature is 350-650 ℃.

3. The method for preparing an amide-modified, Ru quantum dot-supported mixed-crystal C3N5 catalyst according to claim 1, characterized in that: The mass of the C3N5 used in step (2) is 0.1-10 g, and the heating temperature is 500-800 ℃.

4. The method for preparing an amide-modified, Ru quantum dot-supported mixed-crystal C3N5 catalyst according to claim 1, characterized in that: In step (3), the mass of RuCl3·3H2O used is 0.01-10 g, the volume of deionized water is 1-1000 mL, the mass of MC3N5 is 0.1-10 g, the vacuum drying temperature is 30-100 ℃, and the time is 1-48 h.

5. The method for preparing an amide-modified, Ru quantum dot-supported mixed-crystal C3N5 catalyst according to claim 1, characterized in that: The mass of the RQ / MC3N5 precursor used in step (4) is 0.01-10 g, and the heating temperature is 100-800 ℃.

6. The method for preparing an amide-modified, Ru quantum dot-supported mixed-crystal C3N5 catalyst according to claim 1, characterized in that: The mass of VC used in step (5) is 0.01-10 g, the volume of deionized water is 1-1000 mL, and the mass of RQ / MC3N5 is 0.01-10 g.

7. The method for preparing an amide-modified, Ru quantum dot-supported mixed-crystal C3N5 catalyst according to claim 1, characterized in that: In step (6), the reaction temperature of the solvothermal reactor is 80-350 ℃, the vacuum drying temperature is 30-100 ℃, and the time is 1-48 h.

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