A rapid preparation method of chlorophyll-sensitized modified cadmium sulfide nanomaterial

Abstract

The application discloses a kind of chlorophyll sensitized modified cadmium sulfide nanomaterials rapid preparation method, belong to photochemical energy conversion, photocatalytic degradation field.The present application is to solve the technical problems of high-quality preparation of natural organic dye sensitized semiconductor composite material and how to effectively improve photochemical energy conversion efficiency.The method of the present application: one, cadmium nitrate tetrahydrate and thioacetamide are dissolved in triethylene glycol, after being stirred sufficiently, the solution is transferred to the reaction kettle with polytetrafluoroethylene lining and heated, after being cooled to room temperature, it is washed multiple times and dried in vacuum drying oven, to obtain cadmium sulfide (CdS) powder;Two, fresh spinach leaves are added to ethanol and ground, then soaked in anhydrous ethanol, to obtain chlorophyll solution by absorbing supernatant;Three, cadmium sulfide nanomaterials obtained in step one and chlorophyll solution and anhydrous ethanol obtained in step two are ground to dryness under infrared lamp irradiation, to obtain chlorophyll sensitized modified cadmium sulfide (Chl@CdS) nanomaterials.

Description

Technical Field

[0001] This invention belongs to the field of photochemical energy conversion and photocatalytic degradation. Background Technology

[0002] With the progress of the times and the development of science and technology, the massive consumption of non-renewable energy sources such as coal, oil, and natural gas, and the extensive use of fossil fuels, have brought serious energy consumption and environmental pollution problems to mankind. Since Akira Fujishima et al. achieved photocatalytic water splitting to produce hydrogen in 1970, semiconductor photocatalysis technology has been considered the cleanest and most effective technology to solve these problems. The principle of semiconductor photocatalysis technology is that when a photocatalyst is irradiated with light of energy greater than or equal to its band gap, valence band electrons jump to the conduction band, generating freely moving electrons and holes. These electrons, along with the vacancies left by the electron transitions, act as charge carriers and various free radicals generated by the reaction of charge carriers with water, such as superoxide radicals and hydroxyl radicals, to carry out redox reactions, thereby degrading pollutants or generating clean energy.

[0003] Among various semiconductor photocatalytic materials, transition metal sulfides have attracted widespread attention. Cadmium sulfide (CdS), in particular, is considered a promising photocatalyst due to its narrow bandgap, high potential, low cost, and high activity. However, in practical photocatalytic reactions, cadmium sulfide alone is prone to photocorrosion, leading to a decrease in photocatalytic efficiency and limiting its application. Therefore, extensive research has been conducted on the modification of cadmium sulfide, with several modification methods widely reported, such as doping with metal and non-metal elements and constructing heterojunctions with other materials. Notably, sensitizing semiconductors with organic dyes is also a commonly used surface modification method. Dye sensitization can improve the absorption range of semiconductor materials for visible light, suppress carrier recombination, extend carrier lifetime, and enhance the redox capability of semiconductors. However, conventional organic dyes suffer from difficulties in synthesis routes, high environmental toxicity, and low yields, limiting the practical application of this modification technology. Thanks to the natural organic pigments found in the roots, stems, and leaves of green plants, such as anthocyanins and chlorophyll, these pigments offer advantages such as rapid extraction, simple operation, abundant reserves, low price, and environmental friendliness, making them better suited for the role of surface-sensitized modification of semiconductors. Chlorophyll is the most important substance for photosynthesis in plants and a natural light absorber. As a natural organic macromolecule, its central part consists of four pyrrole rings linked by magnesium ions, exhibiting high quantum absorption efficiency with a near-full solar spectrum response. When chlorophyll is combined with semiconductors, it acts as a "gateway" for absorbing a large amount of photon energy. Electrons in its molecular ground state orbitals are excited and transition to high-energy orbitals, and can be transferred in large quantities to the conduction band of adjacent components, completing the spatial separation of photogenerated carriers and the injection of photogenerated charges into the surface of inorganic materials. This modification strategy effectively extends the lifetime of photogenerated carriers and enhances the catalytic ability of the material.

[0004] In summary, this invention proposes a rapid preparation method for chlorophyll-sensitized modified nanomaterials. This method combines the prepared cadmium sulfide nanomaterials and extracted natural chlorophyll through a rapid grinding process aided by infrared light irradiation, causing the two components to combine on their surfaces. Chlorophyll molecules modify the cadmium sulfide surface, allowing photons irradiated onto the cadmium sulfide to both excite internal electron transitions and successfully inject photogenerated electrons from the chlorophyll into the cadmium sulfide surface. This process not only enhances the stability of the nano-cadmium sulfide and inhibits surface photocorrosion but also improves the material's photocatalytic activity. The components are tightly bound, and the method is convenient, rapid, and environmentally friendly. This invention organically combines natural plant extracts with artificial materials, offering a convenient, efficient, and energy-saving approach that aligns with a low-carbon, low-energy-consumption development strategy. Summary of the Invention

[0005] This invention relates to solving the problems of surface modification of cadmium sulfide nanomaterials and optimization of light stability and photocatalytic performance. It proposes a rapid and simple preparation strategy that organically and efficiently combines natural plant extracts and artificial structures. To solve the above problems, the rapid preparation method of chlorophyll-sensitized modified cadmium sulfide nanomaterials in this invention is completed through the following steps.

[0006] Step 1: Dissolve cadmium nitrate tetrahydrate and thioacetamide in triethylene glycol. After stirring thoroughly, transfer the solution to a polytetrafluoroethylene-lined reactor and heat it. After cooling to room temperature, wash it several times and vacuum dry it to obtain cadmium sulfide (CdS) powder.

[0007] Step 2: Grind fresh spinach leaves with ethanol, then soak them in anhydrous ethanol. Extract the supernatant to obtain a chlorophyll solution.

[0008] Step 3: Grind the cadmium sulfide powder obtained in Step 1, the chlorophyll solution obtained in Step 2, and anhydrous ethanol under infrared lamp irradiation until dry to obtain chlorophyll-sensitized modified cadmium sulfide powder (Chl@CdS).

[0009] Further specifying, in step one, 1.73~3.21 g of cadmium nitrate tetrahydrate and 0.53~0.98 g of thiourea are added to 60 mL of triethylene glycol.

[0010] Further specifying, the stirring and dissolving time in step one is 60 min.

[0011] Further specified, the heating temperature in step one is 160~220 ℃, and the holding time is 10~14 h.

[0012] Further specifying, in step one, 60 Vacuum drying at ℃ for 12 h.

[0013] Further specify that the amount of spinach leaves used in step two is 80-120 g, and the amount of anhydrous ethanol is 200-300 mL.

[0014] Further specifying, the soaking time in step two is 8~12 hours.

[0015] Further specifying, in step three, 0.10~0.20 g of cadmium sulfide powder and 0.35~2.25 mL of chlorophyll solution are mixed and ground with 10~30 mL of anhydrous ethanol.

[0016] The chlorophyll-sensitized cadmium sulfide nanomaterial catalyst prepared by the method of this invention involves loading and modifying the surface of artificially synthesized CdS nanoparticles with naturally extracted plant chlorophyll. This modification strategy employs a simple and rapid wet grinding process supplemented with infrared light irradiation, ensuring thorough grinding and mixing of plant chlorophyll and CdS, and stabilizing the organic molecules on the surface of the inorganic material. This invention provides a novel natural-artificial modification strategy that, through the sensitization of the cadmium sulfide surface by chlorophyll, achieves efficient utilization of photons, rapid transfer of photogenerated electrons, and improved photocatalytic activity. Attached Figure Description

[0017] Figure 1 XRD patterns of CdS and Chl@CdS; Figure 2 Surface photovoltage spectra of various types; Figure 3 The surface photovoltage phase spectrum of each sample; Figure 4 Mott-Schottky electrochemical test lines for CdS and Chl@CdS; Figure 5 Electrochemical impedance spectral lines for CdS and Chl@CdS; Figure 6 The UV-Vis absorption spectra of each sample, the band gap diagram of each sample, the photocatalytic reduction degradation curve of each sample with 30 mL of 40 mg / L potassium dichromate indicator over time, and the photocatalytic oxidation degradation curve of each sample with 30 mL of 5 mg / L rhodamine B indicator over time are shown. Implementation

[0018] Example 1: The CdS nanoparticles used in this example were prepared according to the following steps: 2.47 g of cadmium nitrate tetrahydrate [Cd(NO3)2·4H2O] and 0.75 g of thioacetamide (C2H5NS) were dissolved in 60 mL of triethylene glycol (C6H5NS). 14 O4) and stir for 60 min, then transfer the mixture to a 100 mL reactor liner and heat at 200 °C. Heating reaction at ℃ for 12 After h, cool to room temperature. Wash three times each with anhydrous ethanol and deionized water, and then sterilize under vacuum for 60 h. Dry at ℃ for 12 h.

[0019] The chlorophyll-sensitized modified cadmium sulfide nanomaterial and its preparation method in this embodiment are accomplished through the following steps.

[0020] Step 1: Dissolve 2.47 g of cadmium nitrate tetrahydrate and 0.75 g of thioacetamide in 60 mL of triethylene glycol. After stirring for 60 min, transfer the resulting mixture to a 100 mL reactor liner and heat at 200 °C for 12 minutes. h. The obtained product was washed three times with anhydrous ethanol and three times with deionized water, and then dried under vacuum at 60 °C for 12 h to obtain CdS powder.

[0021] Step 2: Grind 100 g of fresh spinach leaves with ethanol, then soak them in 250 mL of anhydrous ethanol for 10 h. After soaking, extract the supernatant to obtain a chlorophyll solution. Chlorophyll is denoted as Chl.

[0022] Step 3: Grind 0.15 g of cadmium sulfide powder with 0.50 mL, 1.00 mL, and 2.00 mL of chlorophyll solution respectively with 20 mL of anhydrous ethanol under infrared lamp irradiation until dry to obtain CdS powder with different chlorophyll surface loading, which are denoted as 0.05wt%Chl@CdS, 0.1wt%Chl@CdS, and 0.2wt%Chl@CdS respectively.

[0023] The photocatalytic reduction degradation of potassium dichromate solution was performed using a 300 W xenon lamp simulating sunlight. 20 mg of the catalyst and 30 mL of a 40 mg / L potassium dichromate solution were placed in a 100 mL beaker. The photocatalytic oxidation degradation of rhodamine B solution was also performed using a 300 W xenon lamp simulating sunlight. 10 mg of the catalyst and 30 mL of a 5 mg / L rhodamine B solution were placed in a 100 mL beaker. The beaker was fixed 5 cm in front of the light source, and the reaction was continuously stirred magnetically at a constant speed. The absorbance of the reaction solution was measured at equal time intervals, and the concentration of the reaction solution was calculated. A curve showing the degradation rate versus illumination time was plotted to analyze and compare the photocatalytic activity of the samples. Figure 6 As shown.

[0024] from Figure 6As can be seen, the 0.1wt% Chl@CdS sample exhibited the fastest degradation rate, taking only 50 seconds to degrade 87% of the potassium dichromate indicator solution in the photocatalytic reduction reaction; and only 15 minutes to degrade 97% of the rhodamine B indicator solution in the photocatalytic oxidation reaction. These performance characteristics demonstrate that chlorophyll-sensitized cadmium sulfide nanomaterials possess a unique photogenerated electron migration pathway, creating favorable conditions for charge spatial separation. This not only extends the lifetime of photogenerated electrons but also effectively increases their reactive thermodynamic potential, macroscopically manifesting as a significant improvement in the material's photocatalytic performance.

Claims

1. The application of a chlorophyll-sensitized cadmium sulfide nanomaterial in the photocatalytic reduction degradation of potassium dichromate or the photocatalytic oxidation degradation of rhodamine B, characterized in that, A rapid preparation method for chlorophyll-sensitized modified cadmium sulfide nanomaterials is achieved through the following steps: Step 1: Dissolve cadmium nitrate tetrahydrate and thiourea in triethylene glycol, stir thoroughly, transfer the solution to a polytetrafluoroethylene-lined reactor, heat, cool to room temperature, wash repeatedly, and dry in a vacuum drying oven to obtain cadmium sulfide powder; Step 2: Grind fresh spinach leaves with ethanol, soak them in anhydrous ethanol, and extract the supernatant to obtain a chlorophyll solution; Step 3: Grind the cadmium sulfide nanomaterials obtained in Step 1, the chlorophyll solution obtained in Step 2, and anhydrous ethanol under infrared lamp irradiation until dry to obtain chlorophyll-sensitized modified cadmium sulfide powder. In step one, 1.73~3.21 g of cadmium nitrate tetrahydrate and 0.53~0.98 g of thiourea are added to 60 mL of triethylene glycol; In step one, the heating temperature is 160~220 ℃, and the holding time is 10~14 h; In step three, 0.11~0.20 g of cadmium sulfide powder, 0.35~2.25 mL of chlorophyll solution, and 10~30 mL of anhydrous ethanol are placed in a mortar, ground, and dried.

2. The application according to claim 1, characterized in that, The stirring and dissolving time in step one is 60 minutes.

3. The application according to claim 1, characterized in that, In step one, the temperature is maintained at 60°C for 12 hours in a vacuum drying oven.

4. The application according to claim 1, characterized in that, In step two, the amount of spinach leaves used is 80-120 g, and the amount of anhydrous ethanol used is 200-300 mL.

5. The application according to claim 1, characterized in that, In step two, the soaking time is 8-12 hours.

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