A Cu-doped MnMoO4 photocatalyst, its preparation method and application

Abstract

This invention belongs to the field of photocatalytic materials technology, specifically relating to a Cu-doped MnMoO4 photocatalyst, its preparation method, and its applications. The preparation method involves grinding copper sulfate pentahydrate into a MnMoO4 precursor. By changing the molar ratio of the copper source, MnMoO4-x%Cu composite materials with different molar ratios are obtained, which can be applied to the photocatalytic water splitting for hydrogen evolution. Compared to existing photocatalysts, the Cu-doped MnMoO4 of this invention exhibits good controllability as a catalyst, which is beneficial for further improving carrier separation efficiency. When applied to photocatalytic water splitting, it shows high hydrogen production and good stability. This invention is environmentally friendly, the method is simple, easy to operate, and the material preparation cost is low, conforming to the currently advocated green and environmentally friendly concept and possessing broad application market prospects.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to a Cu-doped MnMoO4 photocatalyst, its preparation method, and its application. Background Technology

[0002] In recent years, energy shortages and environmental damage have severely hampered sustainable social development, making the development of efficient and green hydrogen resources a key focus for most researchers. Hydrogen, as an environmentally friendly, sustainable, and renewable energy source, is gaining increasing popularity because it has the potential to alleviate energy shortages caused by the overuse of fossil fuels. To date, many methods for producing hydrogen have been established, including high-temperature water splitting and electrocatalytic water cracking. In particular, photocatalytic water splitting for hydrogen production is easy to operate and widely applicable, making it a potential environmentally friendly technology; however, achieving high-efficiency hydrogen production is not easy. Therefore, a key issue in high-performance photocatalytic water splitting for hydrogen evolution technology is exploring photocatalysts capable of effectively achieving charge separation.

[0003] MnMoO4 has attracted widespread attention and application due to its simple synthesis, environmental friendliness, good stability, and suitable band structure. However, the photocatalytic efficiency of pure MnMoO4 photocatalysts is usually limited, mainly due to its significantly low efficiency in harnessing sunlight and the large amount of charge recombination during photogeneration. Therefore, various modification techniques have been designed to improve the photocatalytic efficiency of MnMoO4 for hydrogen production; however, there are no reports on Cu-doped MnMoO4 as a photocatalyst for hydrogen evolution. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a Cu-doped MnMoO4 photocatalyst, its preparation method, and its application.

[0005] The technical solution adopted in this invention is as follows:

[0006] A Cu-doped MnMoO4 photocatalyst, wherein the Cu doping amount is 1-3% of the MnMoO4 by molar percentage.

[0007] The preparation method of the Cu-doped MnMoO4 photocatalyst described above includes the following steps: (NH4)2MoO4 and MnSO4·H2O are added to a mortar and ground to form a uniform precursor powder; CuSO4·5H2O is added to the precursor powder, and after further grinding to uniformity, it is transferred to a high-temperature muffle furnace for calcination reaction. After the reaction is completed, it is cooled to room temperature to obtain the Cu-doped MnMoO4 photocatalyst.

[0008] Preferably, in the above preparation method, the molar ratio is (NH4)2MoO4:MnSO4·H2O=1:5.

[0009] Preferably, in the above preparation method, the calcination reaction conditions are: reacting at 600°C for 3 hours with a heating rate of 5°C / min.

[0010] The application of the Cu-doped MnMoO4 photocatalyst provided by this invention in photocatalytic water splitting for hydrogen production under visible light irradiation.

[0011] Preferably, the above application is carried out by the following method: Cu-doped MnMoO4 photocatalyst is uniformly dispersed in a mixed solution of deionized water, triethanolamine (TEOA) and chloroplatinic acid, and argon gas is continuously introduced at a constant flow rate and irradiated under visible light irradiation conditions.

[0012] Preferably, the concentration of triethanolamine is 7.2 mmol / mL; and the concentration of chloroplatinic acid is 0.75 wt%.

[0013] Preferably, the solid-liquid ratio is Cu-doped MnMoO4:deionized water:triethanolamine:chloroplatinic acid = 20mg:18mL:3mL:20μL.

[0014] The beneficial effects of this invention are as follows:

[0015] 1. This invention utilizes a hydrothermal method to prepare Cu-doped MnMoO4 photocatalysts. After Cu doping modification, impurity energy levels are generated in the original band structure, reducing the electron transition barrier and effectively reducing the recombination of photogenerated electrons and holes, thereby improving the carrier separation efficiency and significantly enhancing the visible light response of the catalyst and strengthening its photocatalytic activity.

[0016] 2. The Cu-doped MnMoO4 photocatalyst prepared by this invention has a larger specific surface area and more effective photogenerated electron and hole separation capabilities, as well as stronger photocatalytic reduction capabilities, and participates in catalytic reactions. It is an effective way to improve visible light photocatalytic activity.

[0017] 3. The Cu-doped MnMoO4 photocatalyst prepared by this invention has good photocatalytic hydrogen evolution performance, and the method is simple, convenient, low-cost, mild, and conducive to large-scale production. Attached Figure Description

[0018] Figure 1 X-ray diffraction patterns of the MnMoO4, MnMoO4-1%Cu, MnMoO4-2%Cu and MnMoO4-3%Cu photocatalysts prepared in Example 1.

[0019] Figure 2 Photocurrent-time curves of the MnMoO4, MnMoO4-1%Cu, MnMoO4-2%Cu and MnMoO4-3%Cu photocatalysts prepared in Example 1.

[0020] Figure 3 Comparison of the photocatalyst activities for water splitting and hydrogen evolution of MnMoO4, MnMoO4-1%Cu, MnMoO4-2%Cu and MnMoO4-3%Cu prepared in Example 1. Detailed Implementation

[0021] Example 1 Cu-doped MnMoO4 photocatalyst (I) Preparation of MnMoO4

[0022] 1 mmol (NH4)2MoO4 and 5 mmol MnSO4·H2O were placed in a mortar and mixed evenly to form a precursor powder. The powder was then placed in a porcelain boat and reacted in a high-temperature muffle furnace at 600℃ for 3 hours with a heating rate of 5℃ / min. After natural cooling to room temperature, MnMoO4 was obtained.

[0023] (II) Preparation of MnMoO4 photocatalyst with 1% Cu doping

[0024] 1 mmol (NH4)2MoO4 and 5 mmol MnSO4·H2O were placed in a mortar and mixed evenly to form a precursor powder. Then, 0.01 mmol CuSO4·5H2O was added and mixed evenly. The mixture was then ground for 30 min. After being ground evenly, the mixture was transferred to a porcelain boat and reacted in a high-temperature muffle furnace at 600℃ for 3 h with a heating rate of 5℃ / min. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a MnMoO4 photocatalyst with a Cu doping content of 1%, labeled as MnMoO4-1%Cu.

[0025] (III) Preparation of MnMoO4 photocatalyst with 2% Cu doping

[0026] 1 mmol (NH4)2MoO4 and 5 mmol MnSO4·H2O were placed in a mortar and mixed evenly to form a precursor powder. Then, 0.02 mmol CuSO4·5H2O was added and mixed evenly. The mixture was then ground for 30 min. After being ground evenly, the mixture was transferred to a porcelain boat and reacted in a high-temperature muffle furnace at 600℃ for 3 h with a heating rate of 5℃ / min. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a MnMoO4 photocatalyst with a Cu doping content of 1%, labeled as MnMoO4-2%Cu.

[0027] (iv) Preparation of MnMoO4 photocatalyst with 3% Cu doping

[0028] 1 mmol (NH4)2MoO4 and 5 mmol MnSO4·H2O were placed in a mortar and mixed evenly to form a precursor powder. Then, 0.03 mmol CuSO4·5H2O was added and mixed evenly. The mixture was then ground for 30 min. After being ground evenly, the mixture was transferred to a porcelain boat and reacted in a high-temperature muffle furnace at 600℃ for 3 h with a heating rate of 5℃ / min. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a MnMoO4 photocatalyst with a Cu doping content of 3%, labeled as MnMoO4-3%Cu.

[0029] (V) Testing

[0030] Figure 1 X-ray diffraction patterns of the MnMoO4, MnMoO4-1%Cu, MnMoO4-2%Cu and MnMoO4-3%Cu photocatalysts prepared in Example 1. Figure 1 In the figure, five significant characteristic diffraction peaks at 2θ = 12.9°, 22.7°, 25.7°, 27.7°, and 37.7° correspond to the (100), (021), (220), (-311), and (040) crystal planes of MnMoO4, respectively (standard card PDF#72-0285). From Figure 1 No characteristic peaks of other impurities were observed, indicating that Cu doping of MnMoO4 still retains the original structure of MnMoO4.

[0031] Example 2: Application of Cu-doped MnMoO4 photocatalyst in catalytic water splitting and hydrogen evolution under light irradiation

[0032] The method is as follows: Under normal temperature and pressure, 18 mL of deionized water, 3 mL of 7.2 mmol / mL TEOA solution, and 20 μL of 0.75 wt% chloroplatinic acid aqueous solution were added to a container. Then, 20 mg of the MnMoO4, MnMoO4-1%Cu, MnMoO4-2%Cu, and MnMoO4-3%Cu photocatalysts prepared in Example 1 were added respectively. The mixture was sonicated for 10 min to obtain a dispersion. Argon gas was introduced into the container at a rate of 40 mL / min for 30 min. The container was sealed, and under visible light irradiation, 1000 μL of gas was taken from the container every 30 min using a microsyringe. The composition of the sample gas was detected by gas chromatography, and the hydrogen evolution concentration was determined.

[0033] Figure 2 Photocurrent-time curves of the MnMoO4, MnMoO4-1%Cu, MnMoO4-2%Cu, and MnMoO4-3%Cu photocatalysts prepared in Example 1 are shown. The results indicate that the photocurrent intensity of MnMoO4-2%Cu is approximately 1.84 μA·cm. -2 It is pure MnMoO4 (0.65 μA·cm⁻¹). -2The efficiency of Cu doping is 2.83 times that of photogenerated carriers in semiconductors. This indicates that Cu doping improves the separation efficiency of photogenerated carriers in semiconductors, thereby enhancing the photoelectrochemical performance of semiconductors.

[0034] Figure 3 This is a comparison of the photocatalyst activities for water splitting and hydrogen evolution of MnMoO4, MnMoO4-1%Cu, and MnMoO4-2%Cu prepared in Example 1. Figure 3 It can be seen that after 2.5 h of light irradiation, the hydrogen production of MnMoO4 reached a maximum of 279 μmol·g. -1 ·h -1 The highest H2 production from MnMoO4-1%Cu reached 410 μmol·g. -1 ·h -1 The highest H2 production from MnMoO4-2%Cu reached 690 μmol·g. -1 ·h -1 The highest H2 production from MnMoO4-3%Cu reached 589 μmol·g. -1 ·h -1 The photocatalytic hydrogen production performance of Cu-doped MnMoO4 is significantly improved compared to pure MnMoO4. This indicates that Cu-doped MnMoO4 exhibits stronger photogenerated electron transport and transfer capabilities, and stronger redox capabilities for electrons and holes.

Claims

1. The application of a Cu-doped MnMoO4 photocatalyst in the catalytic splitting of water to produce hydrogen under visible light irradiation, characterized in that, The Cu-doped MnMoO4 photocatalyst has a Cu doping amount of 1-3% of MnMoO4 by molar percentage.

2. The application according to claim 1, characterized in that, The preparation method of Cu-doped MnMoO4 photocatalyst includes the following steps: (NH4)2MoO4 and MnSO4·H2O are added to a mortar and ground to form a uniform precursor powder; CuSO4·5H2O is added to the precursor powder, and after grinding to uniformity, it is transferred to a high-temperature muffle furnace for calcination reaction. After the reaction is completed, it is cooled to room temperature to obtain Cu-doped MnMoO4 photocatalyst.

3. The application according to claim 2, characterized in that, The molar ratio is (NH4)2MoO4:MnSO4·H2O = 1:

5.

4. The application according to claim 2, characterized in that, The calcination reaction conditions are: reacting at 600°C for 3 hours at a rate of 5°C / min.

5. The application according to claim 1, characterized in that, The method is as follows: Cu-doped MnMoO4 photocatalyst is uniformly dispersed in a mixed solution of deionized water, triethanolamine and chloroplatinic acid, and argon gas is continuously introduced at a constant flow rate and irradiated under visible light.

6. The application according to claim 5, characterized in that, The concentration of triethanolamine is 7.2 mmol / mL; the concentration of chloroplatinic acid is 0.75 wt%.

7. The application according to claim 6, characterized in that, Based on the solid-liquid ratio, Cu-doped MnMoO4:deionized water:triethanolamine:chloroplatinic acid = 20mg:18mL:3mL:20μL.

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