Photocatalyst for hydrogen production by reforming formaldehyde solution and preparation method thereof
By modifying C3N4 photocatalysts with Mn and Ni bimetallic doping, the problems of narrow light absorption range, carrier recombination, and high cost in the formaldehyde solution reforming hydrogen production process in the prior art have been solved. This has enabled efficient formaldehyde degradation and stable hydrogen production under sacrificial agent-free conditions, improved the activity and stability of the catalyst, reduced costs, and reduced environmental pollution.
Patent Information
- Application Number
- CN202512000752.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-02-24
AI Technical Summary
Existing photocatalysts for hydrogen production from formaldehyde solution reforming suffer from problems such as narrow visible light absorption range, low solar energy utilization, easy recombination of photogenerated electron-hole pairs, limited catalytic activity, small specific surface area, and high cost. Furthermore, most reforming reactions require the addition of sacrificial agents, leading to environmental pollution.
A C3N4 photocatalyst modified with Mn and Ni bimetallic doping was used to prepare MnxNiy/C3N4 photocatalysts via sodium borohydride reduction and calcination in a reducing atmosphere. This enabled efficient formaldehyde degradation and stable hydrogen production under sacrificial agent-free conditions. The electronic structures of Mn and Ni were used to modify the band structure of C3N4, broadening the light absorption range and suppressing carrier recombination.
The catalyst achieves efficient degradation and stable hydrogen production of formaldehyde solution at room temperature without sacrificial agents, with a hydrogen production performance of 134.53 mmol·g⁻¹·h⁻¹. This significantly improves the activity and stability of the catalyst, reduces costs, and minimizes environmental pollution.
Smart Images
Figure CN121551047A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the interdisciplinary field of catalyst preparation and hydrogen energy technology, specifically relating to a novel bimetallic supported photocatalyst for hydrogen production from formaldehyde solution reforming and its preparation method.
[0002] Background Area
[0003] Formaldehyde, a volatile organic pollutant widely generated in industrial production, not only poses a serious threat to the ecological environment and human health, but is also a compound rich in hydrogen (with a hydrogen mass fraction of 12.6%). By using photocatalytic technology to reform formaldehyde solution to produce hydrogen, we can realize the resource utilization of pollutants and produce clean energy, which meets the strategic needs of "environmental protection and energy" coordinated development and has important practical significance and application prospects.
[0004] In the field of photocatalysis, the performance of the catalyst directly determines the reaction efficiency and industrialization feasibility. Developing photocatalytic materials that combine high activity, high stability, and low cost is key to driving the technology's implementation. Graphitic carbon nitride (C3N4), as a novel layered semiconductor material similar to graphene, has attracted widespread interest from researchers due to its unique advantages. The C and N atoms within this material are separated by sp... 2 Hybridization forms a highly delocalized π-conjugated structure, which can promote the efficient migration of surface electrons. It also possesses outstanding properties such as ease of synthesis, high cost-effectiveness, strong chemical and thermal stability, narrow band gap (~2.7 eV), and low toxicity, thus attracting widespread research and application in the field of photocatalysis. However, the original C3N4 material suffers from inherent defects such as a narrow visible light absorption range, low solar energy utilization, easy recombination of photogenerated electron-hole pairs, limited catalytic activity, low specific surface area, and insufficient reactive sites, severely restricting further improvement of its photocatalytic performance. Elemental doping, as an effective strategy to optimize its catalytic performance, can improve light utilization and redox capacity by regulating the band gap structure, while simultaneously constructing new active sites or defects in the material to suppress carrier recombination.
[0005] In the specific application of formaldehyde solution reforming for hydrogen production, the activity, stability, and cost of the catalyst directly affect the practical value of the technology. Although noble metal catalysts exhibit excellent activity and stability in the formaldehyde cracking reaction at room temperature, their high cost and resource scarcity limit their practical application. Therefore, transition metal catalysts have become a more promising alternative. Among them, 3d metals, due to their unique electronic structure, show particularly outstanding potential in C3N4 doping modification. Manganese (Mn) and nickel (Ni), as common 3d metals, are not only abundant and inexpensive, but their electronic configurations and catalytic properties can also be precisely adapted to the modification requirements of C3N4. This is mainly achieved by changing the band structure of C3N4, significantly regulating its electronic, optical, and physical properties: on the one hand, metals can introduce defects or change the crystal structure in C3N4, and these defects can act as electrons (electrons). - ) and holes (h + The capture centers of the C3N4 matrix effectively extend the lifetime of photogenerated carriers and reduce recombination probability. Furthermore, the d orbitals of transition metals can hybridize with the molecular orbitals of the C3N4 framework, thereby reducing the band gap, broadening the visible light absorption range, and improving solar energy utilization. It is hoped that high-performance photocatalytic materials can be constructed through doping modification, addressing the performance defects of the original C3N4 while avoiding the application limitations of noble metal catalysts. In addition, manganese and nickel metals possess magnetic properties, which greatly facilitates the recycling and reuse of photocatalysts, reducing separation costs in subsequent applications and further improving the economic viability of the technology.
[0006] Meanwhile, most reforming reactions improve hydrogen production performance by adding sacrificial agents, but this leads to increased costs and environmental pollution, limiting its application in practical engineering. Therefore, developing a photocatalytic material that requires no sacrificial agents, has high hydrogen yield, is cost-effective, and is easily recyclable is of great significance for promoting the industrial application of photocatalysis technology in formaldehyde solution reforming for hydrogen production. Summary of the Invention
[0007] To address the shortcomings of existing transition metal photocatalyst hydrogen production technologies, such as low catalytic efficiency and high dependence on sacrificial agents in the reaction system, which significantly increase the cost of industrial applications and cause secondary environmental problems due to the consumption and residue of sacrificial agents, thus severely restricting their large-scale promotion in the field of hydrogen energy production, this invention provides a novel photocatalyst and its preparation method, aiming to enable the catalyst to exhibit excellent photocatalytic hydrogen production performance of formaldehyde solution reforming under mild reaction conditions without sacrificial agents.
[0008] The present invention is achieved through the following technical solutions.
[0009] This invention provides a photocatalyst for hydrogen production from formaldehyde solution reforming. The catalyst is a bimetallic material with a different Mn / Ni molar ratio; the molecular formula of the photocatalyst is Mn. x Ni y / C3N4, in which x : y = (0~4):1; the total mass of the Mn and Ni bimetals accounts for 6% of the mass of the carrier C3N4.
[0010] Furthermore, the photocatalyst has the molecular formula MnNi / C3N4.
[0011] This invention also provides a method for preparing the above-mentioned photocatalyst, specifically including the following preparation steps:
[0012] (1) C3N4 was dispersed in deionized water as a carrier, and then manganese acetate and nickel chloride solutions were added, stirred and mixed, and labeled as solution A;
[0013] (2) Take another small beaker, add deionized water and place it in an ice-water bath. Use Na2CO3 to adjust the pH to 10 to inhibit the hydrolysis of NaBH4. After cooling, add NaBH4 and stir until dissolved. Label it as solution B.
[0014] (3) Add solution B to solution A dropwise using a peristaltic pump at an initial low flow rate. When solution A begins to change color, increase the flow rate appropriately to accelerate the metal reduction process. After the addition is complete, continue stirring to ensure the reaction is complete. After the reaction is complete, centrifuge, dry, calcine at high temperature under a hydrogen atmosphere, and grind in sequence to finally obtain Mn. x Ni y / C3N4 photocatalyst.
[0015] Furthermore, the stirring time for both steps (1) and (3) is 10 min.
[0016] Furthermore, in step (3), the initial low flow rate is 0.2 mL / min, and the flow rate is increased to 0.5 mL / min after the solution changes color.
[0017] Furthermore, the high-temperature calcination in the hydrogen atmosphere in step (3) refers to the following: the hydrogen atmosphere concentration is 1%H2(Ar) to 10%H2(Ar), the calcination temperature is 500 to 600 ℃, and the calcination time is 2 to 4 h.
[0018] The aforementioned photocatalyst can be applied to the photocatalytic production of hydrogen in formaldehyde solution at room temperature.
[0019] Compared with the prior art, the present invention has the following technical effects:
[0020] 1. The Mn synthesized in this invention x Ni yThe C3N4 photocatalyst can simultaneously achieve formaldehyde degradation and stable hydrogen production in a room-temperature environment without sacrificial agents. Furthermore, its hydrogen production performance is optimal (134.53 mmol·g⁻¹) in an oxygen-rich environment with a solution pH of 3 and a formaldehyde concentration of 28%. -1 ·h -1 Its strong industrial adaptability and significant application prospects provide new catalyst selection and design ideas for the field of hydrogen production technology.
[0021] 2. This invention provides a simple and cost-effective preparation process. Its core innovation lies in the combined use of sodium borohydride reduction and reducing atmosphere calcination, which not only achieves in-situ epitaxial growth of Ni3C on a C3N4 matrix but also promotes high dispersion of Mn in C3N4, ultimately successfully synthesizing Mn with excellent structural properties. x Ni y / C3N4 photocatalyst.
[0022] 3. The Mn synthesized in this invention x Ni y / C3N4 material has excellent light absorption properties and can also be used in other photocatalytic reaction processes, such as photocatalytic water splitting to produce hydrogen or photocatalytic CO2 reduction reaction. Attached Figure Description
[0023] Figure 1 This is a flowchart illustrating the preparation process of the catalyst material synthesized in this invention.
[0024] Figure 2 Photocatalytic hydrogen production activity test data for formaldehyde solution reforming of different samples (test conditions: oxygen environment, solution pH=3, formaldehyde concentration of 28%).
[0025] Figure 3 The graph shows the photocatalytic hydrogen production activity test data of Mn1Ni1 / C3N4 samples under different formaldehyde concentrations (test conditions: oxygen environment, solution pH=3).
[0026] Figure 4 The graph shows the photocatalytic hydrogen production activity test data of Mn1Ni1 / C3N4 samples under different pH conditions (test conditions: oxygen environment, formaldehyde concentration of 28%).
[0027] Figure 5 The graph shows the change in hydrogen production performance of the Mn1Ni1 / C3N4 material obtained in this invention over time (test conditions: oxygen environment, solution pH=3, formaldehyde concentration of 28%).
[0028] Figure 6 Different proportions of Mn obtained in this invention x Ni y X-ray diffraction patterns of C3N4 and pure C3N4 materials.
[0029] Figure 7 Different proportions of Mn obtained in this invention x Ni y / UV-diffuse reflectance spectra of C3N4 and pure C3N4 materials. Detailed Implementation
[0030] The technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0031] Example 1
[0032] Weigh 1.00 g of carbon nitride (obtained by calcining melamine powder in a muffle furnace at 550 ℃ for 4 h) and dissolve it in 100 mL of deionized water while stirring. Then, add 10 mL of a 6.00 mg / mL manganese acetate solution (6% of the mass of C3N4) dropwise, and continue stirring for 10 min to obtain solution A. In a separate small beaker, add deionized water and place it in an ice-water bath. Adjust the pH to 10 with sodium carbonate to inhibit the hydrolysis of sodium borohydride. After cooling, add 0.10 g of sodium borohydride and stir until dissolved, labeling this solution B. Then, use a peristaltic pump to add solution B dropwise to solution A at an initial flow rate of 0.2 mL / min. After solution A begins to change color, increase the flow rate to 0.5 mL / min to promote metal reduction. After the addition is complete, continue stirring for 10 min to ensure the reaction is complete. After the reaction was completed, the catalyst was centrifuged and dried, and finally calcined at 500 °C for 2 h in a hydrogen atmosphere (10% H2 (Ar)) to obtain (6 wt%) Mn / C3N4 catalyst.
[0033] Example 2
[0034] Weigh 1.00 g of carbon nitride (obtained by calcining melamine powder in a muffle furnace at 550 ℃ for 4 h) and dissolve it in 100 mL of deionized water while stirring. Then, add 10 mL of a 6.00 mg / mL nickel chloride solution (6% of the mass of C3N4) dropwise, and continue stirring for 10 min to obtain solution A. In a separate small beaker, add deionized water and place it in an ice-water bath. Adjust the pH to 10 with sodium carbonate to inhibit the hydrolysis of sodium borohydride. After cooling, add 0.10 g of sodium borohydride and stir until dissolved, labeling this solution B. Then, use a peristaltic pump to add solution B dropwise to solution A at an initial flow rate of 0.2 mL / min. After solution A begins to change color, increase the flow rate to 0.5 mL / min to promote metal reduction. After the addition is complete, continue stirring for 10 min to ensure the reaction is complete. After the reaction was completed, the catalyst was centrifuged and dried, and finally calcined at 500 °C for 2 h in a hydrogen atmosphere (10% H2 (Ar)) to obtain (6wt%) Ni / C3N4 catalyst.
[0035] Example 3
[0036] Weigh 1.00 g of carbon nitride (obtained by calcining melamine powder in a muffle furnace at 550 ℃ for 4 h) and dissolve it in 100 mL of deionized water while stirring. Then, add 2.5 mL of a 6.00 mg / mL manganese acetate solution and 7.5 mL of a 6.00 mg / mL nickel chloride solution (6% of the mass of C3N4), and continue stirring for 10 min to obtain solution A. In a separate small beaker, add deionized water and place it in an ice-water bath. Adjust the pH to 10 with sodium carbonate to inhibit the hydrolysis of sodium borohydride. After cooling, add 0.10 g of sodium borohydride and stir until dissolved, labeling this solution B. Then, use a peristaltic pump to add solution B dropwise to solution A at an initial flow rate of 0.2 mL / min. After solution A begins to change color, increase the flow rate to 0.5 mL / min to promote metal reduction. After the addition is complete, continue stirring for 10 min to ensure the reaction is complete. After the reaction was completed, centrifugation and drying were performed, and finally calcination was carried out at 500 °C for 2 h in a hydrogen atmosphere (10% H2 (Ar)) to obtain (6wt%) Mn1Ni3 / C3N4 catalyst.
[0037] Example 4
[0038] Weigh 1.00 g of carbon nitride (obtained by calcining melamine powder in a muffle furnace at 550 ℃ for 4 h) and dissolve it in 100 mL of deionized water while stirring. Then, add 5.0 mL of a 6.00 mg / mL manganese acetate solution and 5.0 mL of a 6.00 mg / mL nickel chloride solution (6% of the mass of C3N4), and continue stirring for 10 min to obtain solution A. In a separate small beaker, add deionized water and place it in an ice-water bath. Adjust the pH to 10 with sodium carbonate to inhibit the hydrolysis of sodium borohydride. After cooling, add 0.10 g of sodium borohydride and stir until dissolved, labeling this solution B. Then, use a peristaltic pump to add solution B dropwise to solution A at an initial flow rate of 0.2 mL / min. After solution A begins to change color, increase the flow rate to 0.5 mL / min to promote metal reduction. After the addition is complete, continue stirring for 10 min to ensure the reaction is complete. After the reaction was completed, the catalyst was centrifuged and dried, and finally calcined at 500 °C for 2 h in a hydrogen atmosphere (10% H2 (Ar)) to obtain (6wt%) Mn1Ni1 / C3N4 catalyst.
[0039] Example 5
[0040] Weigh 1.00 g of carbon nitride (obtained by calcining melamine powder in a muffle furnace at 550 ℃ for 4 h) and dissolve it in 100 mL of deionized water while stirring. Then, add 7.5 mL of a 6.00 mg / mL manganese acetate solution and 2.5 mL of a 6.00 mg / mL nickel chloride solution (6% of the mass of C3N4), and continue stirring for 10 min to obtain solution A. In a separate small beaker, add deionized water and place it in an ice-water bath. Adjust the pH to 10 with sodium carbonate to inhibit the hydrolysis of sodium borohydride. After cooling, add 0.10 g of sodium borohydride and stir until dissolved, labeling this solution B. Then, use a peristaltic pump to add solution B dropwise to solution A at an initial flow rate of 0.2 mL / min. After solution A begins to change color, increase the flow rate to 0.5 mL / min to promote metal reduction. After the addition is complete, continue stirring for 10 min to ensure the reaction is complete. After the reaction was completed, the catalyst was centrifuged and dried, and finally calcined at 500 °C for 2 h in a hydrogen atmosphere (10% H2 (Ar)) to obtain (6wt%) Mn3Ni1 / C3N4 catalyst.
[0041] in, Figure 1 The flowcharts show the preparation process of the catalyst materials in Examples 1-5.
[0042] Example 6
[0043] The catalysts prepared in Examples 1 to 5 were subjected to activity determination and comparative analysis. The test method was as follows: 0.01 g of catalyst was weighed and mixed with 10 mL of formaldehyde solution in a reactor, and a vacuum was drawn. High-purity oxygen was then introduced into the solution for 10 min, after which the reactor was sealed. After adsorption in the dark for 1 h under magnetic stirring at 800 r / min, a photocatalytic reaction was carried out for 2 h under xenon lamp irradiation. The generated hydrogen gas was quantitatively analyzed by gas chromatography, and the data are shown below. Figure 2 As shown. Further parameter optimization revealed that altering the formaldehyde concentration and solution pH significantly affected hydrogen production performance (see...). Figure 3 and 4 The best performance was observed under the conditions of a Ni to Mn ratio of 1:1, solution pH=3, and formaldehyde concentration of 28%, where the catalyst achieved a peak hydrogen production rate of 134.53 mmol·g⁻¹. -1 ·h -1 Compared to the original C3N4 material, its activity increased by approximately 4484 times. Simultaneously, stability tests were conducted on the Mn1Ni1 / C3N4 material (see...). Figure 5 It exhibits good catalytic stability.
[0044] Example 7
[0045] Different proportions of Mn prepared in Example 1 x Ni y C3N4 and C3N4 materials underwent two characterization tests. X-ray diffraction patterns ( Figure 6 The image clearly shows that the co-doping of metallic Mn and Ni alters the crystal phase structure of C3N4, revealing NiO and Ni3C compositions. Ultraviolet-diffuse reflectance spectroscopy (UV-DDR) Figure 7 It was found that the introduction of Mn and Ni broadened the light absorption range of C3N4.
Claims
1. A photocatalyst for hydrogen production from formaldehyde solution reforming, characterized in that, The photocatalyst is a bimetallic structure material with different Mn and Ni molar ratios; The photocatalyst has the molecular formula Mn. x Ni y / C3N4, in this molecular formula: x : y = (0~4): 1; The total mass of the Mn and Ni bimetals accounts for 6% of the mass of the C3N4 carrier.
2. The photocatalyst for hydrogen production from formaldehyde solution reforming as described in claim 1, characterized in that, The photocatalyst has the molecular formula MnNi / C3N4.
3. The method for preparing a photocatalyst for hydrogen production from formaldehyde solution reforming as described in claim 1, characterized in that... The preparation steps include the following: (1) C3N4 was dispersed in deionized water as a carrier, and then manganese acetate and nickel chloride solutions were added, stirred and mixed, and labeled as solution A; (2) Take another small beaker, add deionized water and place it in an ice-water bath. Use Na2CO3 to adjust the pH to 10 to inhibit the hydrolysis of NaBH4. After cooling, add NaBH4 and stir until dissolved. Label it as solution B. (3) Add solution B to solution A dropwise using a peristaltic pump at an initial low flow rate. When solution A begins to change color, increase the flow rate appropriately to accelerate the metal reduction process. After the addition is complete, continue stirring to ensure the reaction is complete. After the reaction is complete, centrifuge, dry, calcine at high temperature under a hydrogen atmosphere, and grind in sequence to finally obtain Mn. x Ni y / C3N4 photocatalyst.
4. The method for preparing the photocatalyst for hydrogen production from formaldehyde solution reforming as described in claim 3, characterized in that, The stirring time for both steps (1) and (3) is 10 min.
5. The method for preparing the photocatalyst for hydrogen production from formaldehyde solution reforming as described in claim 3, characterized in that, The initial low flow rate in step (3) is 0.2 mL / min, and the flow rate is increased to 0.5 mL / min after the solution changes color.
6. The method for preparing the photocatalyst for hydrogen production from formaldehyde solution reforming as described in claim 3, characterized in that, The high-temperature calcination in step (3) under a hydrogen atmosphere refers to a hydrogen atmosphere concentration of 1%H2(Ar)-10%H2(Ar), a calcination temperature of 500-600 ℃, and a calcination time of 2-4 h.
7. The application of the photocatalyst as described in claim 1 in the photocatalytic production of hydrogen from formaldehyde solution at room temperature.