A molybdenum-doped cadmium zinc sulfide solid solution photocatalyst, a preparation method and application thereof

Abstract

The application relates to a molybdenum-doped cadmium zinc sulfide solid solution photocatalyst and a preparation method and application thereof. 0.3 Cd 0.7 S matrix, and the molybdenum doping amount is 1-6% of the total molar amount of Zn and Cd. The molybdenum-doped cadmium zinc sulfide solid solution photocatalyst provided by the application can form Mo-based atomic-level defect clusters with extremely high adsorption and catalytic activity, so that the adsorption activation of aromatic diols is significantly improved, and the dehydrogenation reaction of the aromatic diols is accelerated to prepare hydrogen and aromatic alcohol ketones. The photocatalytic efficiency is extremely high, aromatic diols can be converted into hydrogen and high-value-added chemicals aromatic alcohol ketones through one-step catalytic reaction under sunlight irradiation, the conversion rate of the aromatic diol substrate can be close to 100% when the reaction time is 60-90 min, the selectivity of the product aromatic alcohol ketone is good, and can be up to 100%, that is, no side reaction occurs.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology containing molybdenum sulfides, specifically relating to a molybdenum-doped zinc cadmium sulfide solid solution photocatalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen energy plays a crucial role in the current and future energy structure due to its high energy density and green, pollution-free nature. However, current hydrogen production technologies are still limited to traditional non-renewable energy sources such as industrial by-product hydrogen production and coal and natural gas hydrogen production, resulting in significant carbon emissions. Furthermore, water electrolysis hydrogen production technology is not yet widely adopted due to its extremely high cost, making large-scale production impossible. Therefore, more economical hydrogen production methods need to be researched.

[0003] In addition, traditional synthesis methods in the field of fine chemical synthesis cannot escape harsh conditions, such as high temperature and pressure, strong oxidants and reducing agents, resulting in high energy consumption and large carbon emissions.

[0004] Based on this, the present invention proposes a molybdenum-doped zinc cadmium sulfide solid solution photocatalyst, which converts inexpensive organic raw material phenylethylene glycol into hydrogen and high-value-added chemical α-hydroxyacetophenone in a subsequent reaction under sunlight irradiation, thereby realizing green hydrogen production and green and environmentally friendly organic synthesis, and has great commercial application potential. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the shortcomings of the existing technology by providing a molybdenum-doped zinc cadmium sulfide solid solution photocatalyst, its preparation method and application. This photocatalyst can convert the inexpensive organic raw material phenylethylene glycol into hydrogen and the high-value-added chemical α-hydroxyacetophenone through a further reaction under sunlight.

[0006] This invention provides a molybdenum-doped zinc cadmium sulfide solid solution photocatalyst, wherein the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst is composed of Mo-doped Zn 0.3 Cd 0.7 The substrate is obtained by using S matrix, with Mo doping amount of 1-6% of the total molar amount of Zn and Cd.

[0007] Preferably, the Mo doping amount is 2.5% to 3.5% of the total molar amount of Zn and Cd.

[0008] The present invention also provides a method for preparing the above-mentioned molybdenum-doped zinc cadmium sulfide solid solution photocatalyst, the specific steps of which are as follows: Cadmium acetylacetonate (Cd(acac)2), zinc acetylacetonate (Zn(acac)2), and molybdenum oxyacetyl acetylacetonate (MoO2(acac)2) are added to ethylene glycol and heated and stirred to dissolve to obtain a mixed solution. Then, thioacetamide is added to the obtained mixed solution, and after stirring evenly, a solvothermal reaction is carried out. After the reaction is completed, the solid product is separated and purified to obtain the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst.

[0009] According to the above scheme, the molar ratio of cadmium acetylacetone, zinc acetylacetone, and molybdenum acetylacetone is 8-50:8-50:1.

[0010] According to the above scheme, the mass-to-volume ratio of cadmium acetylacetonate to ethylene glycol is 0.015–0.016 g / mL.

[0011] According to the above scheme, the heating and stirring dissolution temperature is 90-110℃, and the time is 30-60 minutes.

[0012] According to the above scheme, the molar ratio of cadmium acetylacetonate to thioacetamide is 1:2.2 to 2.7.

[0013] According to the above scheme, the solvothermal reaction temperature is 170-190℃ and the time is 1-3h.

[0014] The present invention also includes the application of the above-mentioned molybdenum-doped zinc cadmium sulfide solid solution photocatalyst in the photocatalytic dehydrogenation reaction of aromatic diols to produce hydrogen and aromatic alcohols and ketones.

[0015] Specifically, the present invention includes the application of the above-mentioned molybdenum-doped zinc cadmium sulfide solid solution photocatalyst in the photocatalytic dehydrogenation reaction of phenylethylene glycol to produce hydrogen and α-hydroxyacetophenone.

[0016] According to the above scheme, the specific application method is as follows: dissolve phenyl ethylene glycol in an organic solvent, then add the above molybdenum-doped zinc cadmium sulfide solid solution photocatalyst, mix evenly (inert gas is introduced into the system to remove air), and carry out photocatalytic reaction under sunlight irradiation.

[0017] The reaction formula is as follows:

[0018]

[0019] Preferably, the mass ratio of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst to phenylethylene glycol is 1:0.7 to 1.4.

[0020] Preferably, the organic solvent is anhydrous acetonitrile, and the mass-to-volume ratio of phenylethylene glycol to the organic solvent is 1.25–1.75 mg / mL.

[0021] Preferably, the photocatalytic reaction time is 60–90 min.

[0022] This invention uses an appropriate amount of Mo-doped Zn 0.3 Cd 0.7 S yields a doped solid solution nanocatalyst. The Mo doping sites and the in-situ formed Zn vacancies constitute an atomically dispersed cluster of active defects. This not only enhances the separation rate of photogenerated carriers but also provides a large number of atomically active catalytic sites, thereby improving the efficiency of hydrogen production and the synthesis of α-hydroxyacetophenone. Furthermore, the reaction exhibits high selectivity, with no side reactions or impurities. Under simulated sunlight irradiation, it can efficiently catalyze the acceptorless dehydrogenation of the organic substrate phenylethylene glycol, simultaneously yielding hydrogen and the high-value-added chemical α-hydroxyacetophenone.

[0023] The beneficial effects of this invention are as follows: 1. The molybdenum-doped zinc cadmium sulfide solid solution photocatalyst provided by this invention can form Mo-based atomic-level defect clusters with extremely high adsorption and catalytic activity, thereby significantly enhancing the adsorption and activation of aromatic diols and accelerating their dehydrogenation reaction to produce hydrogen and aromatic ketones. The photocatalytic efficiency is extremely high, enabling aromatic diols to be converted into hydrogen and high-value-added aromatic ketones under sunlight irradiation. When the reaction time is 60–90 min, the conversion rate of the substrate aromatic diol can approach 100%, and the selectivity of the product aromatic ketones is good, reaching up to 100%, meaning no side reactions occur. 2. The preparation method provided by this invention has simple steps, mild reaction conditions, and is easy to scale up for production. Attached Figure Description

[0024] Figure 1 This is a field emission scanning electron microscope image of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in Example 2 of the present invention;

[0025] Figure 2 This is a high-angle annular dark-field image with spherical aberration correction of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in Example 2;

[0026] Figure 3 The elemental distribution diagram is shown for the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in Example 2.

[0027] Figure 4 X-ray diffraction patterns of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in Example 2 and the undoped zinc cadmium sulfide solid solution photocatalyst prepared in Comparative Example 1.

[0028] Figure 5 Raman spectra of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in Example 2 and the undoped zinc cadmium sulfide solid solution photocatalyst prepared in Comparative Example 1.

[0029] Figure 6The image shows a comparison of the photocatalytic activities of the molybdenum-doped zinc cadmium sulfide solid solution photocatalysts prepared in Examples 1-3 and the undoped zinc cadmium sulfide solid solution photocatalyst in Comparative Example 1.

[0030] Figure 7 The image shows a comparison of high-performance liquid chromatography (HPLC) values ​​at different times for the photocatalytic reaction of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in Example 2. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below using embodiments and in conjunction with the accompanying drawings.

[0032] Comparative Example 1

[0033] The preparation method of the undoped zinc cadmium sulfide solid solution photocatalyst is as follows:

[0034] 0.3106 g Cd(acac)₂ (1 mmol) and 0.2636 g Zn(acac)₂ (1 mmol) were added together to a 50 mL single-necked flat-bottomed flask containing 20 mL ethylene glycol. The flask was heated to 100 °C using an oil bath while being magnetically stirred at 500 rpm for 30 min until completely dissolved, yielding a white mixed solution. Then, 0.1880 g thioacetamide (2.5 mmol) was added to the resulting mixed solution, resulting in an orange-yellow turbid dispersion. Subsequently, the dispersion was heated to 180 °C and held at 500 rpm for 1 h for further processing. A thorough solvothermal reaction was carried out to obtain a yellow reaction solution. After the reaction was completed, the solution was allowed to cool naturally for 30 minutes. Then, the reaction solution was centrifuged at high speed (10,000 rpm, 5 minutes / time) using a high-speed centrifuge. The supernatant was discarded, and the solution was ultrasonically washed with a mixture of 15 mL ultrapure water and 15 mL anhydrous ethanol. The centrifugation and washing steps were repeated 5 times. The resulting solid product was then placed in a vacuum drying oven and vacuum dried at 60 °C for 24 hours. After drying, the product was ground for 5 minutes to obtain a zinc cadmium sulfide solid solution photocatalyst without molybdenum doping.

[0035] Example 1

[0036] A molybdenum-doped zinc cadmium sulfide solid solution photocatalyst, the specific steps of its preparation are as follows:

[0037] 0.3106 g Cd(acac)₂ (1 mmol), 0.2636 g Zn(acac)₂ (1 mmol), and 0.0058 g MoO₂(acac)₂ (0.02 mmol) were added to a 50 mL single-necked flat-bottomed flask containing 20 mL ethylene glycol. The flask was heated to 100 °C using an oil bath and stirred magnetically at 500 rpm for 30 min until completely dissolved, yielding a white mixed solution. Then, 0.1880 g thioacetamide (2.5 mmol) was added to the resulting mixed solution, resulting in an orange-yellow turbid dispersion. Subsequently, the dispersion was heated to 180 °C and held at 500 rpm for 1 h to allow for a complete solvothermal reaction, yielding a light brown reaction product. After the reaction was completed, the single-necked flat-bottom flask was immediately removed and placed in ice water to cool for 30 minutes. Then, the reaction solution was centrifuged at high speed (10,000 rpm, 5 minutes / time) using a high-speed centrifuge. After discarding the supernatant, the product was ultrasonically washed with a mixture of 15 mL ultrapure water and 15 mL anhydrous ethanol. The centrifugation and washing steps were repeated 5 times. The resulting solid product was then placed in a vacuum drying oven and vacuum dried at 60 °C for 24 hours. After drying, it was ground for 5 minutes to obtain a molybdenum-doped zinc cadmium sulfide solid solution photocatalyst. In this example, the amount of Mo doping in the photocatalyst was 1% of the total molar amount of Zn and Cd.

[0038] Example 2

[0039] A molybdenum-doped zinc cadmium sulfide solid solution photocatalyst, the specific steps of its preparation are as follows:

[0040] 0.3106 g Cd(acac)₂ (1 mmol), 0.2636 g Zn(acac)₂ (1 mmol), and 0.0196 g MoO₂(acac)₂ (0.06 mmol) were added to a 50 mL single-necked flat-bottomed flask containing 20 mL ethylene glycol. The flask was heated to 100 °C using an oil bath while stirring magnetically at 500 rpm until completely dissolved, which took 30 min, resulting in a white mixed solution. Then, 0.1880 g thioacetamide (2.5 mmol) was added to the resulting mixed solution, resulting in an orange-yellow turbid dispersion. Subsequently, the dispersion was heated to 180 °C and held at 500 rpm for 1 h to allow for a complete solvothermal reaction, yielding a light brown [substance / product]. After the reaction was completed, the single-necked flat-bottom flask was immediately removed and placed in ice water to cool for 30 minutes. Then, the reaction solution was centrifuged at high speed (10,000 rpm, 5 minutes / cycle) using a high-speed centrifuge. After discarding the supernatant, the product was ultrasonically washed with a mixture of 15 mL ultrapure water and 15 mL anhydrous ethanol. The centrifugation and washing steps were repeated 5 times. The resulting solid product was then placed in a vacuum drying oven and vacuum dried at 60 °C for 24 hours. After drying, the product was ground for 5 minutes to obtain a molybdenum-doped zinc cadmium sulfide solid solution photocatalyst. In this example, the Mo doping amount in the photocatalyst was 3% of the total molar amount of Zn and Cd.

[0041] like Figure 1 The image shown is a field emission scanning electron microscope (FESEM) image of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in this embodiment. As can be seen from the image, the photocatalyst is an aggregate of uniform nanoparticles with a particle size of about 10 nm, and the diameter of the aggregates varies from 50 to 500 nm.

[0042] Figure 2 and Figure 3 The images shown are aberration-corrected high-angle annular dark-field images and elemental distribution maps of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in this embodiment. Figure 2 It can be seen that the photocatalyst nanoparticles contain atomic-level defect clusters (formed by the coupling of heteroatoms Mo and Zn vacancies). From Figure 3 As can be seen, a small amount of Mo is uniformly dispersed throughout the photocatalyst nanoparticles, while Zn, Cd, and S are uniformly distributed in large quantities throughout the photocatalyst nanoparticles.

[0043] Figure 4 The X-ray diffraction patterns of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in this embodiment and the undoped zinc cadmium sulfide solid solution photocatalyst prepared in Comparative Example 1 are shown. It can be found that, compared with the undoped sample, the characteristic diffraction peaks of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in this embodiment have not changed, indicating that the molybdenum-doped sample has good lattice stability.

[0044] Figure 5 The images show the Raman spectra of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in this embodiment and the undoped zinc cadmium sulfide solid solution photocatalyst prepared in Comparative Example 1. By comparing with Comparative Example 1, it was found that the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in this embodiment showed the stretching vibration signal of the Mo-S bond, indicating the successful incorporation of molybdenum.

[0045] Example 3

[0046] A molybdenum-doped zinc cadmium sulfide solid solution photocatalyst, the specific steps of its preparation are as follows:

[0047] 0.3106 g Cd(acac)₂ (1 mmol), 0.2636 g Zn(acac)₂ (1 mmol), and 0.0392 g MoO₂(acac)₂ (0.12 mmol) were added to a 50 mL single-necked flat-bottom flask containing 20 mL ethylene glycol. The flask was heated to 100 °C using an oil bath while stirring magnetically at 500 rpm until completely dissolved, which took 30 min, resulting in a white mixed solution. Then, 0.1880 g thioacetamide (2.5 mmol) was added to the resulting mixed solution, resulting in an orange-yellow turbid dispersion. The dispersion was then heated to 180 °C and held at 500 rpm for 1 h to allow for a complete solvothermal reaction, yielding... The light brown reaction solution was immediately removed from the single-necked flat-bottom flask after the reaction was completed and placed in ice water to cool for 30 minutes. Then, the reaction solution was centrifuged at high speed (10,000 rpm, 5 minutes / cycle) using a high-speed centrifuge. After discarding the supernatant, the product was ultrasonically washed with a mixture of 15 mL ultrapure water and 15 mL anhydrous ethanol. The centrifugation and washing steps were repeated 5 times. The resulting solid product was then placed in a vacuum drying oven for vacuum drying. After drying, the product was ground for 5 minutes to obtain a molybdenum-doped zinc cadmium sulfide solid solution photocatalyst. In this example, the Mo doping amount in the photocatalyst was 6% of the total molar amount of Zn and Cd.

[0048] Application Examples

[0049] A method for testing the activity of a molybdenum-doped zinc cadmium sulfide solid solution photocatalyst in the photocatalytic dehydrogenation of phenylethylene glycol to produce hydrogen and α-hydroxyacetophenone is described below:

[0050] 0.03 g of molybdenum-doped zinc cadmium sulfide solid solution photocatalyst, 0.0332 g of phenylethylene glycol as the reaction substrate, and 20 mL of anhydrous acetonitrile were added to a 621 mL quartz glass reaction vessel. The reaction vessel was then kept at 0 °C and evacuated for 10 min. Argon gas was then introduced to 80 kPa, and the reaction vessel was kept at 25 °C. Illumination tests were then conducted using a 300 W xenon lamp with an AM 1.5 G bandpass filter, with a light source intensity of 100 mW / cm².2 (Simulating a standard sunlight intensity), the illumination distance was 10 cm, and the illumination time was 1 hour. After the illumination ended, 600 μL of the gaseous product was sampled using an online gas chromatograph for quantitative detection of hydrogen, while 1 mL of the liquid product was sampled, the catalyst was filtered out, and then qualitatively and quantitatively detected using a high-performance liquid chromatograph.

[0051] Figure 6 The graph shows a comparison of the photocatalytic activities of the molybdenum-doped zinc cadmium sulfide solid solution photocatalysts prepared in Examples 1-3 and the undoped zinc cadmium sulfide solid solution photocatalyst in Comparative Example 1. It can be seen that, compared to the zinc cadmium sulfide solid solution photocatalyst in Comparative Example 1, the molybdenum-doped zinc cadmium sulfide solid solution photocatalysts prepared in Examples 1-3 all showed improved photocatalytic activity for the dehydrogenation of phenylethylene glycol, with the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in Example 2 exhibiting the best performance. Specifically, under the catalysis of the photocatalyst prepared in Example 2, the conversion rate of phenylethylene glycol reached over 90% within 1 hour, the evolution rate of hydrogen and α-hydroxyacetophenone reached over 215 μmol / h (stoichiometric ratio close to 1), and the effective ratio of photogenerated electrons and holes was close to 1, indicating that it has the best activity for the dehydrogenation of phenylethylene glycol to produce hydrogen. The carbon balance of around 100% indicates that no other byproducts were obtained in the catalytic process, and the selectivity for α-hydroxyacetophenone was 100%. These results indicate that the optimal Mo doping amount for the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst is 3% of the total molar amount of Zn and Cd.

[0052] Figure 7 The high-performance liquid chromatography (HPLC) comparison of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst prepared in Example 2 under the above conditions at different reaction times shows that no other by-products were produced during the reaction, and the selectivity of the product α-hydroxyacetophenone was 100%.

Claims

1. The application of a molybdenum-doped zinc cadmium sulfide solid solution photocatalyst in the photocatalytic dehydrogenation reaction of aromatic diols to produce hydrogen and aromatic alcohols and ketones, characterized in that, The molybdenum-doped zinc cadmium sulfide solid solution photocatalyst is composed of Mo-doped Zn. 0.3 Cd 0.7 The substrate is obtained with Mo doping amount of 1~6% of the total molar amount of Zn and Cd; The molybdenum-doped zinc cadmium sulfide solid solution photocatalyst contains atomic-level defect clusters formed by the coupling of Mo and Zn vacancies in the nanoparticles. A small amount of Mo is uniformly dispersed throughout the photocatalyst nanoparticles, while Zn, Cd, and S are abundantly and uniformly distributed throughout the photocatalyst nanoparticles.

2. The application of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst according to claim 1 in the photocatalytic dehydrogenation reaction of aromatic diols to produce hydrogen and aromatic alcohols and ketones, characterized in that, The Mo doping amount is 2.5~3.5% of the total molar amount of Zn and Cd.

3. The application of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst according to claim 1 in the photocatalytic dehydrogenation reaction of aromatic diols to produce hydrogen and aromatic alcohols and ketones, characterized in that, The specific steps for preparing the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst are as follows: Cadmium acetylacetonate, zinc acetylacetonate, and molybdenum oxyacetylacetonate are added to ethylene glycol and heated and stirred to dissolve them to obtain a mixed solution. Then, thioacetamide is added to the obtained mixed solution, and after stirring evenly, a solvothermal reaction is carried out. After the reaction is completed, the solid product is separated and purified to obtain the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst.

4. The application of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst according to claim 3 in the photocatalytic dehydrogenation reaction of aromatic diols to produce hydrogen and aromatic alcohols and ketones, characterized in that, The molar ratio of cadmium acetylacetone, zinc acetylacetone, and molybdenum acetylacetone is 8~50:8~50:

1.

5. The application of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst according to claim 3 in the photocatalytic dehydrogenation reaction of aromatic diols to produce hydrogen and aromatic alcohols and ketones, characterized in that, The mass-to-volume ratio of cadmium acetylacetonate to ethylene glycol is 0.015~0.016 g / mL.

6. The application of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst according to claim 3 in the photocatalytic dehydrogenation reaction of aromatic diols to produce hydrogen and aromatic alcohols and ketones, characterized in that, The heating and stirring process is carried out at a temperature of 90~110℃ for 30~60 min.

7. The application of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst according to claim 3 in the photocatalytic dehydrogenation reaction of aromatic diols to produce hydrogen and aromatic alcohols and ketones, characterized in that, The molar ratio of cadmium acetylacetonate to thioacetamide is 1:2.2~2.

7.

8. The application of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst according to claim 3 in the photocatalytic dehydrogenation reaction of aromatic diols to produce hydrogen and aromatic alcohols and ketones, characterized in that, The solvothermal reaction temperature is 170~190℃, and the time is 1~3h.

9. The application of the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst according to claim 1 in the photocatalytic dehydrogenation reaction of aromatic diols to produce hydrogen and aromatic alcohols and ketones, characterized in that, The specific application method is as follows: Phenylethylene glycol is dissolved in an organic solvent, and then the molybdenum-doped zinc cadmium sulfide solid solution photocatalyst is added, mixed evenly, and carried out photocatalytic reaction under sunlight irradiation.

Images