Defective cu-mo co-doped mn 0.5 Cd 0.5 S composite photocatalyst and its application in photocatalysis

Abstract

This invention discloses defect-type Cu-Mo co-doped Mn 0.5 Cd 0.5 S-composite catalysts and their applications in photocatalysis belong to the field of inorganic materials. A simple hot solvent method was used to prepare defect-type Cu-Mo co-doped Mn. 0.5 Cd 0.5 S-composite catalyst, Mn 0.5 Cd 0.5 Sulfur vacancies exist on the S surface, and Mn in the complex 0.5 Cd 0.5 The molar ratio of S, Cu, and Mo is 1:0.01–0.1:0.01–0.1. Mn 0.5 Cd 0.5 The introduction of sulfur vacancies on the S surface not only expands the light absorption range of the catalyst, but also effectively promotes the separation and transport of photogenerated carriers, thereby improving the Mn content. 0.5 Cd 0.5 S exhibits photocatalytic activity under visible light. Furthermore, Cu and Mo bimetallic doping utilizes the complementary effect between the two metal ions to enhance Mn... 0.5 Cd 0.5 With a wider light absorption range and higher carrier separation efficiency, the S composite catalyst exhibits excellent photocatalytic H2O2 production performance.

Description

Technical Field

[0001] This invention belongs to the field of inorganic materials technology, specifically relating to defect-type Cu-Mo co-doped Mn. 0.5 Cd 0.5 S-composite catalysts and their application in photocatalysis. Background Technology

[0002] Hydrogen peroxide (H2O2), as a green and multifunctional chemical raw material, possesses strong oxidizing power and is widely used in pharmaceuticals, textiles, energy, and other fields. Compared to the energy-intensive and complex anthraquinone oxidation method, photocatalytic oxygen reduction reaction (ORR) technology can utilize abundant solar energy to reduce dissolved oxygen in water into H2O2 through photogenerated electrons on a photocatalyst. Among the many photocatalysts for H2O2 production, Mn... x Cd 1-x Sulfur (S), as a low-cost and readily available sulfur solid solution photocatalyst, has shown superior potential in the photocatalytic production of H₂O₂ due to its suitable bandgap structure and tunability. However, due to the influence of Mn... x Cd 1-x The rapid recombination of photogenerated carriers and the lack of active sites in S result in a less than optimistic efficiency for photocatalytic H2O2 production via the reduction of O2 in water. To improve Mn... x Cd 1-x To improve the photocatalytic hydrogen production performance of S materials, various strategies have been employed, such as defect modulation, metal doping, compositing with semiconductor materials, and loading different co-catalysts.

[0003] Defect engineering is considered to improve Mn x Cd 1-x An effective strategy for improving the utilization of photogenerated carriers and light absorption rate of S catalysts has been demonstrated in several studies. Generally, in Mn... x Cd 1-x Introducing surface vacancies or defects formed by surface functional groups into S photocatalysts will provide more trapping sites, promoting electron accumulation and carrier separation. Although the introduction of defects has an impact on Mn... x Cd 1-x S material promotes photocatalytic activity, but single-type defects have a negative impact on Mn. x Cd 1-x The performance improvement of S materials in photocatalytic H2O2 production is limited. x Cd 1-x S forms electron and hole trapping centers on the surface, thereby suppressing the recombination of photogenerated electrons and holes; in addition, doping with transition metal ions can also be applied to Mn. x Cd 1-xIntroducing doping levels into the band gap of S shortens its band gap. Compared to single metal doping, bimetallic doping can utilize the complementary effect between two metal ions to make Mn... x Cd 1-x S has a wider light absorption range and higher carrier separation efficiency.

[0004] This invention uses Mn 0.5 Cd 0.5 Using S nanowires as the main catalyst, defect-type Cu-Mo co-doped Mn was successfully prepared via a simple one-step hot solvent method. 0.5 Cd 0.5 S-type composite catalyst and its application in the photocatalytic preparation of H2O2. In this invention, Mn 0.5 Cd 0.5 The introduction of sulfur vacancies on the S surface can not only expand the light absorption range of the catalyst, but also effectively promote the separation and transport of photogenerated carriers, thereby improving the Mn content. 0.5 Cd 0.5 S exhibits photocatalytic activity under visible light. Co-doping with transition metal ions Cu and Mo can utilize the complementary effect between the two metal ions to enhance the photocatalytic activity of Mn. 0.5 Cd 0.5 S-type light has a wider absorption range and higher carrier separation efficiency. Based on these advantages, the defect-type Cu-Mo co-doped Mn prepared in this invention... 0.5 Cd 0.5 S-type composite catalysts have shown promising applications in the photocatalytic preparation of H2O2. Summary of the Invention

[0005] This invention provides a defect-type Cu-Mo co-doped Mn method that is simple to operate and easy to implement. 0.5 Cd 0.5 S-type composite catalysts, their preparation methods, and their application in photocatalytic H2O2 production; defective Cu-Mo co-doped Mn catalysts prepared by this method. 0.5 Cd 0.5 The S composite catalyst has the advantages of high activity and stable performance in the photocatalytic preparation of H2O2.

[0006] The defect-type Cu-Mo co-doped Mn of the present invention 0.5 Cd 0.5 The S-composite catalyst is characterized by the following structural features: Mn in the composite catalyst 0.5 Cd 0.5 Sulfur vacancies exist on the S surface; Mn 0.5 Cd 0.5The molar ratio of S, Cu, and Mo is 1:0.01-0.1:0.01-0.1; strong diffraction peaks are observed at 25.4°, 27.2°, 28.9°, 37.5°, 44.6°, 49.4°, and 53.0° in the XRD pattern; binding energies are present at 160.8 eV, 162.1 eV, 404.4 eV, 411.2 eV, 640.8 eV, 652.7 eV, 932.9 eV, 952.7 eV, 224.9 eV, and 225.6 eV in the XPS pattern; a sulfur defect signal peak is observed at g = 2.004 in the paramagnetic resonance spectrum; defect-type Cu-Mo co-doped with Mn. 0.5 Cd 0.5 S has a nanowire structure.

[0007] from Figure 1 Mn can be clearly observed in the crystal structure of the XRD sample. 0.5 Cd 0.5 Sample S exhibits strong diffraction peaks at 25.4°, 27.2°, 28.9°, 37.5°, 44.6°, 49.4°, and 53.0°, which are similar to those of Mn. 0.5 Cd 0.5 The S XRD standard spectra are consistent. Furthermore, Cu-doped or Cu-Mo co-doped Mn... 0.5 Cd 0.5 No Cu or Mo compounds were observed in the S XRD pattern, indicating that Cu and Mo doping did not result in the formation of new substances.

[0008] from Figure 2 XPS analysis of defective Cu-Mo co-doped Mn 0.5 Cd 0.5 The elemental composition spectrum of sample S shows that: Mn 2p 3 / 2 and Mn 2p 1 / 2 The binding energies are 640.8 eV and 652.7 eV; Cd 3d 5 / 2 and Cd 3d 3 / 2 The binding energies are 404.4 eV and 411.2 eV; S2p 3 / 2 and S2p 1 / 2 The binding energies are 160.8 eV and 162.1 eV; Cu 2p 3 / 2 and Cu 2p 1 / 2 The binding energies are 932.9 eV and 952.7 eV, with the 225.6 eV binding energy attributed to the Mo-S bond. Furthermore, the XPS spectra show the simultaneous presence of all five elements—S, Mn, Cd, Cu, and Mo—with no other impurity peaks detected, indicating the successful preparation of high-purity Cu-Mo co-doped Mn. 0.5 Cd 0.5 S complex.

[0009] from Figure 3 TEM and SEM morphology analysis revealed that Cu-Mo co-doped with Mn 0.5 Cd 0.5 Sample S exhibits a regular nanowire structure with a length of approximately 2 μm and a diameter of approximately 50 nm.

[0010] from Figure 4 The UV-Vis diffuse reflectance spectrum shows that Cu-Mo is co-doped with Mn. 0.5 Cd 0.5 The absorption band edge of sample S exhibits a red shift, and its absorption performance in the visible light region is significantly stronger than that of undoped Mn. 0.5 Cd 0.5 S indicates that bimetallic doping can further optimize the light absorption performance of the composite catalyst.

[0011] from Figure 5 The transient photocurrent spectrum shows that: Mn 0.5 Cd 0.5 S exhibits a low current density, indicating that only a small number of photogenerated electrons participate in the transfer and separation process; compared with Mn 0.5 Cd 0.5 Compared to S, Cu-doped Cu-Mn 0.5 Cd 0.5 The transient photocurrent intensity of S increases significantly, indicating Cu-Mo co-doped Mn. 0.5 Cd 0.5 The highest S current intensity further proves that bimetallic doping can further accelerate the separation of photogenerated electrons and holes.

[0012] from Figure 6 The electrochemical impedance spectroscopy shows that the Nyquist radii are in the following order: Mn 0.5 Cd 0.5 S>Cu-Mn 0.5 Cd 0.5 S>Mo / Cu-Mn 0.5 Cd 0.5 S indicates that Cu-Mo co-doping can effectively reduce interfacial charge transfer resistance and improve the performance of photocatalytic H2O2 production.

[0013] from Figure 7 The paramagnetic resonance spectrum showed a significant signal peak at g = 2.004, indicating that the prepared Cu-Mo co-doped Mn... 0.5 Cd 0.5 There are S vacancies on the S surface.

[0014] from Figure 8 The photocatalytic H2O2 production experiment shows that pure Mn 0.5 Cd 0.5 Due to rapid charge carrier recombination, S exhibits poor H2O2 performance; after Cu doping, the resulting Cu-Mn...0.5 Cd 0.5 The H2O2 evolution performance of S composite photocatalyst is improved; when Cu and Mo are simultaneously doped into Mn 0.5 Cd 0.5 Cu-Mo co-doped Mn obtained after S 0.5 Cd 0.5 The S composite photocatalyst exhibits the highest H2O2 extraction performance, indicating that the synergistic effect of bimetallic doping can significantly enhance the performance of Mn. 0.5 Cd 0.5 The performance of S-precipitation H2O2.

[0015] This invention relates to defective Cu-Mo co-doped Mn 0.5 Cd 0.5 The method for preparing the S-composite catalyst is characterized by comprising the following steps:

[0016] 1) Dissolve cadmium acetate, manganese acetate, thioacetamide, and copper nitrate in ethylenediamine solution, and then stir the solution evenly at room temperature;

[0017] Furthermore, in the above technical solution, the molar ratio of manganese acetate to cadmium acetate is 1:1; the molar ratio of manganese acetate to thioacetamide is 1:2-4; and the molar ratio of manganese acetate to copper nitrate is 1:0.02-0.2.

[0018] 2) Sodium molybdate was added to the above ethylenediamine solution, and after stirring, the resulting mixed solution was subjected to a hot solvent reaction at 140-200℃ to obtain defect-type Cu-Mo co-doped Mn. 0.5 Cd 0.5 S nanowires.

[0019] Furthermore, in the above technical solution, the molar ratio of manganese acetate to sodium molybdate is 1:0.02-0.2.

[0020] This invention relates to defective Cu-Mo co-doped Mn 0.5 Cd 0.5 Application of S composite catalyst in photocatalytic production of H2O2.

[0021] Furthermore, in the above technical solution, the photocatalytic reaction operating conditions are: 300W xenon lamp as the light source; 100mg of catalyst; 90mL of deionized water; and 10mL of isopropanol. This process is used to prepare H2O2 via photocatalysis. Figure 8 From this, we can see that pure Mn 0.5 Cd 0.5 The photocatalytic production rate of H2O2 by S is 0.83 mmol g. -1 h -1 Cu-doped Mn 0.5 Cd 0.5 The photocatalytic production rate of H2O2 by S is 2.86 mmol g.-1 h -1 Cu and Mo co-doped Mn 0.5 Cd 0.5 The photocatalytic production rate of H2O2 by S is 5.37 mmol g. -1 h -1 This invention exhibits significantly enhanced photocatalytic H2O2 production performance. Beneficial effects of this invention:

[0022] This invention relates to defective Cu-Mo co-doped Mn 0.5 Cd 0.5 The S-composite catalyst has a nanowire structure, in which Mn 0.5 Cd 0.5 The introduction of sulfur vacancies on the S surface can not only expand the light absorption range of the catalyst, but also effectively promote the separation and transport of photogenerated carriers, thereby improving the Mn content. 0.5 Cd 0.5 The photocatalytic activity of S under visible light. Co-doping with transition metal ions Cu and Mo can utilize the complementary effect between the two metal ions to enhance the photocatalytic activity of Mn. 0.5 Cd 0.5 S-light has a wider absorption range and higher carrier separation efficiency, thus enabling defect-type Cu-Mo co-doped Mn 0.5 Cd 0.5 The H2O2 precipitation performance of the S composite photocatalyst is greatly improved. Attached Figure Description

[0023] Figure 1 The Mn prepared in Example 1 of this invention 0.5 Cd 0.5 S, Cu-doped Mn 0.5 Cd 0.5 S and Cu-Mo co-doped Mn 0.5 Cd 0.5 S XRD pattern;

[0024] Figure 2 The defective Cu-Mo co-doped Mn prepared in Example 1 of this invention 0.5 Cd 0.5 S XPS map;

[0025] Figure 3 The defective Cu-Mo co-doped Mn prepared in Example 1 of this invention 0.5 Cd 0.5 SEM image (a) and TEM image (b);

[0026] Figure 4 Mn prepared in Example 1 of this invention 0.5 Cd 0.5 S, Cu-doped Mn 0.5 Cd0.5 S and Cu-Mo co-doped Mn 0.5 Cd 0.5 S UV-Vis diffuse reflectance spectrum.

[0027] Figure 5 Mn prepared in Example 1 of this invention 0.5 Cd 0.5 S, Cu-doped Mn 0.5 Cd 0.5 S and Cu-Mo co-doped Mn 0.5 Cd 0.5 S-transient current spectrum;

[0028] Figure 6 Mn prepared in Example 1 of this invention 0.5 Cd 0.5 S, Cu-doped Mn 0.5 Cd 0.5 S and Cu-Mo co-doped Mn 0.5 Cd 0.5 S-electrochemical impedance spectroscopy;

[0029] Figure 7 The defective Cu-Mo co-doped Mn prepared in Example 1 of this invention 0.5 Cd 0.5 S solid paramagnetic resonance spectrum.

[0030] Figure 8 Mn prepared in Example 1 of this invention 0.5 Cd 0.5 S, Cu-doped Mn 0.5 Cd 0.5 S and Cu-Mo co-doped Mn 0.5 Cd 0.5 Effect diagram of S photocatalytic production of H2O2; Detailed implementation method:

[0031] The present invention is further described below with reference to embodiments. It should be noted that the present invention is not limited to the embodiments described below.

[0032] Example 1

[0033] 1) Dissolve 0.9391g thioacetamide, 0.9926g manganese acetate tetrahydrate, 1.1994g cadmium acetate dihydrate and 0.1087g copper nitrate trihydrate in 60mL ethylenediamine and stir vigorously at room temperature for 30min to make it homogeneous.

[0034] 2) Add 0.1318 g of sodium molybdate dihydrate to the above ethylenediamine solution, continue stirring for 30 min, then transfer the mixture to a 100 mL Teflon-lined stainless steel autoclave and maintain at 160 °C for 24 hours. The resulting sample, after centrifugation, washing, and drying, yields defect-type Cu-Mo co-doped Mn. 0.5 Cd 0.5 S composite photocatalyst.

[0035] Example 2

[0036] 1) Dissolve 0.7513g thioacetamide, 0.9926g manganese acetate tetrahydrate, 1.1994g cadmium acetate dihydrate and 0.0217g copper nitrate trihydrate in 60mL ethylenediamine and stir vigorously at room temperature for 30min to make it homogeneous.

[0037] 2) Add 0.0264 g of sodium molybdate dihydrate to the above ethylenediamine solution, continue stirring for 30 min, then transfer the mixture to a 100 mL Teflon-lined stainless steel autoclave and maintain at 140 °C for 24 hours. The resulting sample, after centrifugation, washing, and drying, yields defect-type Cu-Mo co-doped Mn. 0.5 Cd 0.5 S composite photocatalyst.

[0038] Example 3

[0039] 1) Dissolve 1.5026g thioacetamide, 0.9926g manganese acetate tetrahydrate, 1.1994g cadmium acetate dihydrate and 0.2174g copper nitrate trihydrate in 60mL ethylenediamine and stir vigorously at room temperature for 30min to make it homogeneous.

[0040] 2) Add 0.2636 g of sodium molybdate dihydrate to the above ethylenediamine solution, continue stirring for 30 min, then transfer the mixture to a 100 mL Teflon-lined stainless steel autoclave and maintain at 200 °C for 24 hours. The resulting sample, after centrifugation, washing, and drying, yields defect-type Cu-Mo co-doped Mn. 0.5 Cd 0.5 S composite photocatalyst.

[0041] Example 4: Photocatalytic H2O2 Production Experiment

[0042] 100 mg of catalyst was uniformly dispersed in a mixed solution containing 10 mL of isopropanol and 90 mL of water. After ultrasonic treatment for 10 min, oxygen was continuously introduced and the mixture was stirred in the dark for 30 min. A 300 W xenon lamp was used as the light source for the photocatalytic production of H₂O₂. Figure 8 From this, we can see that pure Mn 0.5 Cd 0.5The photocatalytic H2O2 evolution rate of S is 0.83 mmol g -1 h -1 The Cu-doped Mn obtained in Example 1 0.5 Cd 0.5 The photocatalytic H2O2 evolution rate of S is 2.86 mmol g -1 h -1 The Cu-Mo co-doped Mn obtained in Example 1 was used. 0.5 Cd 0.5 The photocatalytic H2O2 evolution rate of S is as high as 5.37 mmol g. -1 h -1 It exhibits significantly enhanced photocatalytic H2O2 extraction performance.

[0043] The composite photocatalysts prepared using Examples 2-3 achieved similar hydrogen peroxide production effects.

[0044] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its principles, and all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A defective Cu-Mo co-doped Mn for photocatalytic preparation of H2O2 0.5 Cd 0.5 S-composite catalyst, characterized in that: Mn in composite catalysts 0.5 Cd 0.5 Sulfur vacancies exist on the S surface; Mn 0.5 Cd 0.5 The molar ratio of S, Cu, and Mo is 1:0.01-0.1:0.01-0.1; strong diffraction peaks are observed at 25.4°, 27.2°, 28.9°, 37.5°, 44.6°, 49.4°, and 53.0° in the XRD pattern; binding energies are present at 160.8 eV, 162.1 eV, 404.4 eV, 411.2 eV, 640.8 eV, 652.7 eV, 932.9 eV, 952.7 eV, 224.9 eV, and 225.6 eV in the XPS pattern; a sulfur defect signal peak is observed at g = 2.004 in the paramagnetic resonance spectrum; defect-type Cu-Mo co-doped with Mn. 0.5 Cd 0.5 S has a nanowire structure; the defect-type Cu-Mo co-doped Mn 0.5 Cd 0.5 The preparation steps for the S-composite catalyst are as follows: 1) Dissolve cadmium acetate, manganese acetate, thioacetamide, and copper nitrate in ethylenediamine solution, and then stir the solution evenly at room temperature; 2) Sodium molybdate was added to the above ethylenediamine solution, and after stirring, the resulting mixed solution was subjected to a hot solvent reaction at 140-200℃ to obtain defect-type Cu-Mo co-doped Mn. 0.5 Cd 0.5 S-composite catalyst.

2. The catalyst according to claim 1, characterized in that: In step 1), the molar ratio of manganese acetate to cadmium acetate is 1:

1.

3. The catalyst according to claim 1, characterized in that: In step 1), the molar ratio of manganese acetate to thioacetamide is 1:2-4.

4. The catalyst according to claim 1, characterized in that: In step 1), the molar ratio of manganese acetate to copper nitrate is 1:0.02-0.

2.

5. The catalyst according to claim 1, characterized in that: In step 1), the molar ratio of manganese acetate to sodium molybdate in step 2) is 1:0.02-0.

2.

6. The defect-type Cu-Mo co-doped Mn as described in claim 1 0.5 Cd 0.5 Application of S composite catalysts in photocatalytic preparation of H2O2.

7. The defect-type Cu-Mo co-doped Mn according to claim 6 0.5 Cd 0.5 The application of S-composite catalyst in the photocatalytic preparation of H2O2 is characterized by: The operating conditions were as follows: 300 W xenon lamp as the light source; 100 mg catalyst; 90 mL deionized water; and 10 mL isopropanol.

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