Preparation method of composite photocatalytic hydrogen production material MoO3 / CuO

Abstract

The application discloses a preparation method of a composite photocatalytic hydrogen production material MoO3 / CuO and belongs to the technical field of photocatalytic hydrogen production.The method has the advantages of high uniformity, high purity, low cost and the like, and has excellent controllability for the crystal, shape and size of the synthesized photocatalyst.The preparation operation is simple, the required equipment is little, and the safety factor of using molybdenum trioxide as a precursor is higher.The prepared MoO3 / CuO has strong stability and high photocatalytic activity.Under the irradiation of a simulated sunlight xenon lamp, 3mg of the composite photocatalytic hydrogen production material is dispersed in 3mL of a 55mmol / L ascorbic acid aqueous solution, the hydrogen production amount reaches 1797.66nmol after 6h of light irradiation, and the hydrogen production rate can reach 99.87μmol·g ‑1 ·h ‑1 ·h .The prepared product can be widely used in the field of photocatalytic hydrogen production.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic hydrogen production technology, specifically to a method for preparing a composite photocatalytic hydrogen production material MoO3 / CuO. Background Technology

[0002] With rapid economic development, the energy gap is widening, making the development of new clean energy sources an urgent priority. Hydrogen energy has advantages such as high efficiency, safety, and being green and pollution-free, and it occupies an important position among clean energy sources such as solar, wind, and geothermal energy, with broad application prospects. Currently, there are mainly two methods for producing hydrogen: electrolysis of water and photocatalytic water splitting. The former has higher costs, while the latter has the advantages of simple operation and lower cost. However, its efficiency is limited by the catalyst. Therefore, it is necessary to develop a new high-efficiency photocatalyst for water splitting.

[0003] Traditional photocatalysts, such as TiO2 and ZnO, have wide band gaps and extremely low visible light utilization, requiring high excitation energies, which hinders their application in practical production. Molybdenum-based catalysts, on the other hand, exhibit high activity and abundant energy storage. Due to their unique electronic structure and metal-like properties, they have attracted widespread attention and are used as co-catalysts in the photocatalytic water splitting and hydrogen evolution reaction. MoO3, with its special structure and high efficiency, non-toxicity, and low cost, has significant application value in photocatalytic water splitting for hydrogen production. However, its actual application effect and catalytic activity are still limited by its own limitations, such as the limited number of active sites on its surface, poor electron and hole mobility, high recombination rate of photogenerated carriers, and short lifetime, making it difficult to achieve satisfactory results. In recent years, numerous studies have modified MoO3 through methods such as loading, doping, and semiconductor composites to improve its photocatalytic performance. Among these, the formation of heterojunctions by combining other semiconductor materials to expand the photoresponse range of photocatalytic materials, improve overall solar energy utilization and quantum yield, enhance the separation efficiency of photogenerated electron-hole pairs, suppress the recombination of photogenerated carriers, and effectively improve the photocatalytic activity of catalysts has attracted considerable attention from researchers. CuO is a p-type semiconductor material with a band gap of 1.2-1.9 eV, belonging to the monoclinic crystal system. CuO is an important industrial material, widely used not only as a raw material for copper salt production but also in gas sensors, semiconductors, catalysis, and magnetic storage media. For example, in the field of catalysis, it exhibits high catalytic activity for the decomposition of ammonium perchlorate and the complete oxidation of carbon monoxide, ethanol, ethyl acetate, and toluene. Due to its excellent performance, it has the potential to replace noble metal catalysts. Successfully constructing a MoO3 / CuO heterojunction could potentially enhance its photocatalytic performance. Summary of the Invention

[0004] This invention provides a hydrothermal method for preparing the composite photocatalytic hydrogen production material MoO3 / CuO, which improves the activity and stability of the composite photocatalytic material. This preparation method is simple, has a short cycle time, and exhibits high catalytic activity. The preparation method of the composite photocatalytic hydrogen production material MoO3 / CuO of this invention is as follows:

[0005] (1) Preparation of MoO3

[0006] Accurately measure 2.42 g of Na₂MoO₄ and dissolve it in 32 mL of deionized water, stirring for 30 min at room temperature. Then, measure 6.25 mL of HNO₃ and add it to the resulting solution, stirring for another 10 min. Transfer the resulting precursor solution to a 50 mL Teflon-lined stainless steel autoclave and react it in an oven at 220 °C for 12 h. After the autoclave has cooled naturally to room temperature, centrifuge the precipitate five times with anhydrous ethanol. Finally, freeze-dry the centrifuged product under vacuum at -50 °C for 12 h to obtain a white powder, MoO₃.

[0007] (2) Preparation of MoO3 / CuO composite material

[0008] 0.3 g of MoO3 was added to 50 mL of anhydrous ethanol and ultrasonically dispersed for 5 minutes. Then, 0.16 g of copper nitrate was added and stirred for 10 minutes. The mixture was then ultrasonically dispersed for 60 minutes and stirred for another 60 minutes. Finally, the mixture was annealed in air at 550 °C for 2 hours. After cooling, the mixture was ground into powder using a quartz mortar to obtain the composite photocatalytic hydrogen production material MoO3 / CuO.

[0009] The present invention adopts the above technical solution, and has the following main effects:

[0010] (1) The composite photocatalytic hydrogen production material MoO3 / CuO prepared by the method of the present invention, under the irradiation of a xenon lamp (greater than 420 nm) simulating sunlight, 3 mg of MoO3 / CuO photocatalytic hydrogen production material dispersed in 3 mL of 55 mmol / L ascorbic acid aqueous solution, produced 1797.66 nmol of hydrogen after 6 h of irradiation, and the hydrogen production rate reached 99.87 μmol·g. -1 ·h -1 ;

[0011] (2) The present invention uses a hydrothermal method for preparation, which has the advantages of high uniformity, high purity and low cost, and has excellent controllability over the crystals, shape and size of the synthesized photocatalyst. The preparation operation is simple and requires few equipment. Attached Figure Description

[0012] Figure 1 These are SEM images of MoO3 and MoO3 / CuO in embodiments of the present invention;

[0013] Figure 2The XRD patterns of MoO3 and MoO3 / CuO are shown in the embodiments of the present invention.

[0014] Figure 3 This is a comparison chart of hydrogen production rates of MoO3 and MoO3 / CuO in embodiments of the present invention. Detailed Implementation

[0015] The methods and techniques described in this invention are illustrated below through examples, but in practical applications, they are not limited to these examples.

[0016] Example 1

[0017] The MoO3 / CuO photocatalytic hydrogen production material and its preparation method described in this embodiment need to be carried out according to the following steps:

[0018] (1) Preparation of MoO3

[0019] Accurately measure 2.42 g of Na₂MoO₄ and dissolve it in 32 mL of deionized water, stirring for 30 min at room temperature. Then, measure 6.25 mL of HNO₃ and add it to the resulting solution, stirring for another 10 min. Transfer the resulting precursor solution to a 50 mL Teflon-lined stainless steel autoclave and react it in an oven at 220 °C for 12 h. After the autoclave has cooled naturally to room temperature, centrifuge the precipitate five times with anhydrous ethanol. Finally, freeze-dry the centrifuged product under vacuum at -50 °C for 12 h to obtain a white powder, MoO₃.

[0020] (2) Preparation of MoO3 / CuO composite material

[0021] 0.3 g of MoO3 was added to 50 mL of anhydrous ethanol and ultrasonically dispersed for 5 minutes. Then, 0.16 g of copper nitrate was added and stirred for 10 minutes. The mixture was then ultrasonically dispersed for 60 minutes and stirred for another 60 minutes. Finally, the mixture was annealed in air at 550 °C for 2 hours. After cooling, the mixture was ground into powder using a quartz mortar to obtain the composite photocatalytic hydrogen production material MoO3 / CuO.

[0022] Experimental results

[0023] (1) As Figure 1 As shown, the MoO3 prepared by the method of the present invention has a regular rod-shaped morphology, indicating that the prepared MoO3 is uniform and pure; it can be clearly seen from the prepared MoO3 / CuO composite material that some nanoparticles are sparsely dispersed on the surface of MoO3. It can be seen from the figure that the diameter of the composite increases after compositing, which may be due to heat treatment.

[0024] (2) Figure 2As shown, when comparing the MoO3 prepared by the method of this invention with the data of JCPDs 35-0609, all diffraction peaks can be confirmed as orthorhombic MoO3; the XRD pattern of the prepared MoO3 / CuO composite material clearly shows that only MoO3 diffraction peaks appear in the figure, indicating that the content of CuO in the composite material is low.

[0025] (3) Figure 3 As shown, the MoO3 and MoO3 / CuO composite materials prepared by the method of the present invention, under the irradiation of a xenon lamp (greater than 420 nm) simulating sunlight, 3 mg of MoO3 and the MoO3 / CuO composite material were dispersed in 3 mL of 55 mmol / L ascorbic acid aqueous solution. The MoO3 exhibited a hydrogen production of 1229.76 nmol after 6 hours of irradiation, with a hydrogen production rate of 68.32 μmol·g⁻¹. -1 ·h -1 The hydrogen production of MoO3 / CuO under light irradiation for 6 hours reached 1797.66 nmol, and the hydrogen production rate reached 99.87 μmol·g. -1 ·h -1 It is evident that constructing a MoO3 / CuO heterojunction enhances its photocatalytic hydrogen production performance.

[0026] Finally, it should be noted that although the present invention has been described in detail above with general descriptions and specific embodiments, the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite photocatalytic hydrogen production material MoO3 / CuO, comprising the following steps: (1) Preparation of MoO3 2.42 g of Na2MoO4 was accurately measured and dissolved in 32 mL of deionized water. The solution was magnetically stirred for 30 min at room temperature. Then, 6.25 mL of HNO3 was added to the resulting solution and stirred for another 10 min. The resulting precursor solution was transferred to a 50 mL Teflon-lined stainless steel autoclave and reacted in an oven at 220 °C for 12 h. After the autoclave cooled naturally to room temperature, the precipitate was centrifuged five times each with anhydrous ethanol and deionized water. Finally, the centrifuged product was vacuum dried at -50 °C in a freeze dryer for 12 h to obtain white powder MoO3. (2) Preparation of MoO3 / CuO composite material 0.3 g of MoO3 was added to 50 mL of anhydrous ethanol and ultrasonically dispersed for 5 minutes. Then, 0.16 g of Cu(NO3)2 was added and magnetically stirred at room temperature for 10 minutes. After ultrasonic dispersion for 60 minutes, the mixture was stirred for another 60 minutes. The resulting product was dried in air and then annealed in air at 550 °C for 2 hours. After cooling, the product was ground into powder using a quartz mortar to obtain the composite photocatalytic hydrogen production material MoO3 / CuO.

2. The method for preparing the composite photocatalytic hydrogen production material MoO3 / CuO according to claim 1, characterized in that... The hydrothermal method was used to prepare the catalyst, achieving a strong bond between the catalytically active components MoO3 and CuO.

3. All chemical reagents in claim 1 are of analytical grade.

4. The 6.25 mL HNO3 measured in step (1) of claim 1, wherein the mass fraction of HNO3 is 65%.

5. According to step (1) of claim 1, the precipitate is centrifuged five times with anhydrous ethanol and deionized water, respectively, wherein the centrifugation speed is 4000 rpm and the centrifugation time is 20 min each time.

6. According to step (2) of claim 1, the sample is placed in a sealed crucible and then heated in a muffle furnace at a heating rate of 10°C per minute. After heating is completed, the sample is taken out after it cools naturally to room temperature with the furnace.

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