Method for preparing photocatalytic material by using synthesis environment composed of dihydrogen bond system
By controlling the morphology of silver bromide through a double hydrogen bond system composed of a deep eutectic solvent and nanocellulose, the low efficiency problem of existing silver bromide photocatalysts was solved, and high-efficiency photocatalytic performance was achieved.
Patent Information
- Application Number
- CN202510960659.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-11
- Publication Date
- 2025-11-07
Smart Images
Figure CN120903548A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of photocatalytic materials, and particularly relates to a method for preparing a photocatalyst material by regulating the morphology of silver bromide in an environment by using a deep eutectic solvent / nano-cellulose composed double hydrogen bond. BACKGROUND
[0002] Semiconductor photocatalytic technology, as a typical representative of advanced oxidation processes, exhibits significant technical advantages in the field of environmental governance. Through the redox reaction initiated by photo-generated carriers, it can achieve the deep mineralization of refractory organic pollutants. Its core advantages are reflected in three aspects: first, the reaction system has environmental friendly characteristics, which can drive the reaction process using solar energy at normal temperature and pressure, completing the direct conversion of solar energy to chemical energy; second, the photocatalytic degradation process follows the principles of green chemistry, which can completely convert organic pollutants into CO2, H2O and inorganic salts, fundamentally avoiding the problem of secondary pollution caused by intermediate products; third, typical photocatalytic materials represented by TiO2 have cost-effective advantages, with abundant raw material reserves, simple preparation process, and can be recycled and reused by physical cleaning. Photocatalytic materials are effective and sustainable in treating organic pollutants. Unmodified photocatalytic materials have major defects in quantum efficiency, reactivity and stability, which cannot meet the requirements of practical applications. In order to solve the above problems, a simple, economical and green photocatalytic material preparation process needs to be developed.
[0003] Silver bromide is a typical semiconductor photocatalyst, which is considered as a potential photocatalyst due to its wide light response range (band gap of 2.6 eV) and high degradation activity driven by visible light. However, its inherent defects such as low specific surface area, weak stability and low adsorption activity seriously hinder the comprehensive catalytic efficiency. Deep eutectic solvent is a kind of solvent composed of hydrogen bond donor and hydrogen bond acceptor, which has similar properties to ionic liquid. It has a liquid hydrogen bond network, as well as dense and reversible ion-dipole interaction and dipole-dipole interaction. Nano-cellulose also has a unique hydrogen bond network structure. The double hydrogen bond system formed by the combination of the two can limit the growth direction of the crystal, affect the aggregation state and reaction activity of the precursor ions, and then affect the nucleation and growth rate, and regulate the morphology of the photocatalyst. This structure with high customization promotes the separation and migration rate of photo-generated carriers in the photocatalytic process, effectively improving the photocatalytic efficiency. SUMMARY
[0004] The application aims to provide a method for preparing a photocatalytic material by using a synthetic environment composed of a dihydrogen bond system.
[0005] To achieve the above-mentioned object, the technical scheme of the application is as follows.
[0006] The application provides a method for preparing a photocatalytic material by using a synthetic environment composed of a dihydrogen bond system, comprising the following steps: (1) Preparation of a deep eutectic solvent First, lactate and betaine are weighed respectively, heated in a water bath until the mixture forms a uniform solution, and then cooled to room temperature to obtain a deep eutectic solvent. (2) Preparation of a silver bromide photocatalytic material in a deep eutectic solvent / nano-cellulose synthetic environment Nano-cellulose is weighed and dissolved in the deep eutectic solvent to obtain a uniformly mixed nano-cellulose solution, and then silver nitrate solution and potassium bromide solution are added to the nano-cellulose solution, and after the addition is completed, the reaction is stirred at room temperature under acidic conditions. After the reaction is completed, solid-liquid separation, washing and drying are sequentially performed to obtain a rock-like silver bromide photocatalytic material.
[0007] In the application, in step (1), the molar ratio of lactate to betaine is 12:1, the water bath heating temperature is 90-95℃, and the heating time is 1-2h.
[0008] In the application, in step (2), the feeding ratio of the deep eutectic solvent to the nano-cellulose is 1:20~1:30 mL / mg. Nano-cellulose is used to provide a hydrogen bond environment for the synthesis of silver bromide, affect the nucleation and growth rate, and thus regulate the morphology of the photocatalyst.
[0009] In the application, in step (2), the concentration of the silver nitrate aqueous solution is 1:5~1:10 mmol / mL, the concentration of the potassium bromide aqueous solution is 1:5~1:10 mmol / mL, the molar ratio of silver nitrate to potassium bromide is 1:0.9~1:1.1, and the mass ratio of nano-cellulose to silver nitrate is 1.1:1~1.2:1.
[0010] In the application, in step (2), the silver nitrate solution is first added to the nano-cellulose solution, and then the potassium bromide solution is added.
[0011] In the present application, in step (2), after adding the silver nitrate solution and the potassium bromide solution, the pH value is not adjusted, and the stirring reaction is directly carried out at room temperature, or the pH value of the system is adjusted to be between 3.0 and 5.2 by using dilute nitric acid and / or ethylenediamine, and then the stirring reaction is carried out at room temperature.
[0012] In the present application, in step (2), the stirring reaction is carried out at room temperature for 2-3 hours; when the solid-liquid separation is carried out, the filtration or centrifugation method is used, and the solid obtained after the solid-liquid separation is washed with water and ethanol for multiple times, and then dried at a temperature of 60-80 DEG C for 6-18 hours.
[0013] Compared with the prior art, the present application has the following advantages: (1) The preparation process of the present application is simple, and a catalyst synthesis environment composed of a deep eutectic solvent (DES) and a nano-cellulose (CNF) double hydrogen bond system is constructed, and silver bromide with special morphology is synthesized under mild conditions; (2) The silver bromide is prepared at room temperature in the present application, which is energy-saving, environment-friendly, green, pollution-free, low-cost and high-economic value;
[0014] (3) The photocatalytic material prepared in the present application has better performance than pure silver bromide material, the double hydrogen bond system formed in the present application can limit the growth direction of the crystal, affect the aggregation state and reaction activity of the precursor ions, and then affect the nucleation and growth rate, and the morphology of the photocatalyst is adjusted, and the high-efficiency photocatalytic activity comes from the higher active free radical conversion rate and the more active photoelectrochemical properties, and then the photocatalytic performance is improved. BRIEF DESCRIPTION OF DRAWINGS
[0015] Figure 1 It is a scanning electron microscope image of the photocatalytic material prepared in the examples; a) silver bromide, b) DCA3, c) DCA5, d) DCA6, e) DCA.
[0016] Figure 2 It is a transient photocurrent diagram of the photocatalytic material prepared in the examples.
[0017] Figure 3 It is a UV-Vis diffuse reflectance spectrum diagram of the photocatalytic material prepared in the examples.
[0018] Figure 4 It is a photoluminescence spectrum diagram of the photocatalytic material prepared in the examples.
[0019] Figure 5 It is a degradation performance diagram of the photocatalytic material prepared in the examples. DETAILED DESCRIPTION
[0020] The technical solutions of the present application will be described in detail below in combination with the drawings and examples.
[0021] The synthetic environment composed of a double hydrogen bond system is used to prepare a photocatalytic material, and the main reagents include: lactic acid; betaine; nanocellulose; silver nitrate; potassium bromide; dilute nitric acid; and ethylenediamine.
[0022] Example 1
[0023] First, the weighed silver nitrate is dissolved in deionized water, and then the potassium bromide aqueous solution is added. The concentration of the silver nitrate aqueous solution is 0.2 mmol / mL, and the concentration of the potassium bromide aqueous solution is 0.21 mmol / mL. After stirring at room temperature for 3 h, the precipitate is centrifuged, the powder is washed, and the powder is placed in a 60°C oven for 12 h to dry. The finally prepared sample is called AgBr (silver bromide) photocatalytic material.
[0024] Catalytic material degradation rate test: 50 mg of the AgBr (silver bromide) photocatalytic material is placed in a photocatalytic glass reactor, 100 mL of 1*10 -5 mol / L rhodamine B solution is added, and adsorption is performed in the dark for 1 h to reach adsorption equilibrium. Then, a 300 W xenon lamp (λ>420 nm) is turned on for 1 h of photocatalytic reaction. Every 10 min, 3 mL of the mixed solution is taken into a centrifuge tube, the centrifuge tube is placed in a centrifuge for 5 min (at a speed of 5000 rpm), and the supernatant is taken. The concentration of RhB in the supernatant is measured at 554 nm by a UV spectrophotometer. It is measured that the degradation rate of the AgBr (silver bromide) photocatalytic material on RhB within 30 min is 60%.
[0025] Example 2
[0026] 1) Preparation of a deep eutectic solvent Lactic acid and betaine are weighed, and the molar ratio is 12:1. Water bath heating is performed at 90°C for 1-2 h until a uniform solution is formed. After cooling to room temperature, a deep eutectic solvent is obtained.
[0027] 2) Preparation of a catalytic material using a synthetic environment composed of a double hydrogen bond system First, 20 mL of DES (deep eutectic solvent) is mixed with 400 mg of CNF (nanocellulose) at a feed ratio of 1:20 mL / mg. After stirring at room temperature for 30 min, a uniform mixture is formed, which is denoted as DC. Then, 0.34 g of silver nitrate and 0.25 g of potassium bromide are dissolved in 10 mL of deionized water, respectively. The silver nitrate and potassium bromide aqueous solutions are added to the mixed solution in sequence, and the molar ratio of silver nitrate to potassium bromide is 1:1. Dilute nitric acid is used to adjust the pH to 3.0-3.2, and stirring is performed at room temperature for 2 h. Finally, the sample is washed repeatedly with deionized water and ethanol until the sample is colorless and odorless. The washed sample is placed in a 60°C oven for drying for 12 h, and the dried sample is denoted as DCA3.
[0028] 3) Degradation rate test of the catalytic material The experimental method is the same as in Example 1. It is measured that the degradation rate of DCA3 photocatalytic material to RhB within 30 min is 90%.
[0029] Example 3
[0030] 1) Preparation of the deep eutectic solvent is the same as in Example 2.
[0031] 2) Preparation of the catalytic material in the synthetic environment composed of the double hydrogen bond system The other is the same as in Example 2, except that in this example, after adjusting the pH to 5.0-5.2 using ethylenediamine, the reaction is stirred at room temperature. The final photocatalytic material sample obtained in this example is denoted as DCA5, which has a rock-like morphology.
[0032] 3) Degradation rate test of the catalytic material The experimental method is the same as in Example 1. It is measured that the degradation rate of DCA5 photocatalytic material to RhB within 30 min is 99%.
[0033] Example 4
[0034] 1) Preparation of the deep eutectic solvent is the same as in Example 2.
[0035] 2) Preparation of the catalytic material in the synthetic environment composed of the double hydrogen bond system The other is the same as in Example 2, except that in this example, after adjusting the pH to 6.7-6.9 using ethylenediamine, the reaction is stirred at room temperature. The final photocatalytic material sample obtained in this example is denoted as DCA6.
[0036] 3) Degradation rate test of the catalytic material The experimental method is the same as in Example 1. It is measured that the degradation rate of DCA6 photocatalytic material to RhB within 30 min is 80%.
[0037] Example 5
[0038] 1) Preparation of the deep eutectic solvent is the same as in Example 2.
[0039] 2) Preparation of the catalytic material in the synthetic environment composed of the double hydrogen bond system The other is the same as in Example 2, except that in this example, the pH is not adjusted, the initial pH value is 4.7-4.8, and the reaction is stirred at room temperature. The final photocatalytic material sample obtained in this example is denoted as DCA.
[0040] 3) Degradation rate test of the catalytic material The experimental method is the same as in Example 1. It is measured that the degradation rate of DCA photocatalytic material to RhB within 30 min is 95%.
[0041] Figure 1The scanning electron microscope (SEM) image of the photocatalytic material prepared in the embodiment of the present application is shown in the figure. The change in the morphology of the silver bromide can be clearly seen in the SEM image. The particle size of the pure silver bromide material is large and easy to agglomerate. The photocatalytic material with a rock-like morphology is successfully prepared in the synthetic environment composed of the double hydrogen bond system. The particle size of the photocatalytic material is small and not easy to agglomerate, and the active sites can be increased.
[0042] Figure 2 The transient photocurrent graph of the photocatalytic material prepared in the embodiment of the present application is shown in the figure. The transient photocurrent refers to the current generated due to light excitation in a very short time. When light is incident on certain dielectric materials, photons are absorbed by the materials, and then electrons are excited from the valence band to the conduction band to form electron-hole pairs. The size of the transient photocurrent can reflect the catalytic performance of the photocatalyst to some extent, and the two are positively correlated. As can be seen from the figure, the response ability of the DCA5 photocatalytic material is the strongest, and therefore the photocatalytic performance is the strongest.
[0043] Figure 3 The ultraviolet-visible diffuse reflectance spectrum of the photocatalytic material prepared in the embodiment of the present application is shown in the figure. The ultraviolet-visible diffuse reflectance spectrum can be used to study the light absorption performance of the photocatalytic material. Through the spectrum, the light absorption of the material at different wavelengths can be understood, so as to judge the absorption ability of the material to ultraviolet light and visible light. This is of great significance for evaluating the catalytic efficiency of the photocatalytic material under sunlight. As can be seen from the figure, the DCA5 photocatalytic material has stronger absorption ability in the visible light range.
[0044] Figure 4 The photoluminescence spectrum of the photocatalytic material prepared in the embodiment of the present application is shown in the figure. Photoluminescence is a kind of cold light phenomenon, which refers to the process of re-emitting photons after a substance absorbs photons. When the photocatalyst is excited by light, electrons jump from the valence band to the conduction band to form photo-generated electron-hole pairs, i.e. carriers. Part of the carriers will directly recombine inside or on the surface of the material to release energy in the form of photons, thereby generating a PL signal. When the carriers recombine quickly (PL peak intensity), the photo-generated electron-hole pairs participating in the surface catalytic reaction are reduced, and the photocatalytic efficiency is reduced. When the carriers are effectively separated (PL peak is weak), more electrons / hole migrate to the surface to participate in the redox reaction, and the catalytic performance is improved. As can be seen from the figure, the peak intensity of DCA5 at 410 nm is significantly reduced, indicating that the recombination of the carriers is inhibited in the photocatalyst prepared in the DCA5 environment, thereby having strong photocatalytic activity.
[0045] Figure 5 The degradation performance graph of the photocatalytic material prepared in the embodiment of the present application is shown in the figure. Table 1 shows the degradation rate of the catalytic material prepared in the synthetic environment composed of the double hydrogen bond system in the embodiment.
[0046] Table 1 shows the degradation rate of the catalytic material prepared in the synthetic environment composed of the double hydrogen bond system.
[0047] Note: Deep eutectic solvent DES, nanocellulose CNF.
Claims
1. A method for preparing a photocatalytic material using a synthetic environment composed of a double hydrogen bond system, characterized by, Comprising the following steps: (1) Preparation of deep eutectic solvent First, respectively, lactic acid and betaine were mixed, heated in a water bath until a uniform mixture solution was formed; cooled to room temperature to obtain a deep eutectic solvent; (2) Preparation of silver bromide photocatalytic material under deep eutectic solvent / nano-cellulose synthesis environment The nano-cellulose was dissolved in the deep eutectic solvent to obtain a uniformly mixed nano-cellulose solution; then silver nitrate solution and potassium bromide solution were added to the nano-cellulose solution, and after addition, the reaction was carried out under acidic conditions at room temperature with stirring; after the reaction was completed, solid-liquid separation, washing and drying were carried out in sequence to obtain a rock-like silver bromide photocatalytic material.
2. The method of claim 1, wherein, In step (1), the molar ratio of lactic acid to betaine was 12:1, the water bath heating temperature was 90-95℃, and the heating time was 1-2h.
3. The method of claim 1, wherein, In step (2), the feeding ratio of deep eutectic solvent to nano-cellulose was 1:20~1:30 mL / mg.
4. The method of claim 1, wherein, In step (2), the concentration of silver nitrate aqueous solution was 1:5~1:10 mmol / mL, and the concentration of potassium bromide aqueous solution was 1:5~1:10 mmol / mL; the molar ratio of silver nitrate to potassium bromide was 1:0.9~1:1.1, and the mass ratio of nano-cellulose to silver nitrate was 1.1:1~1.2:
1.
5. The method of claim 1, wherein, In step (2), the silver nitrate solution was first added to the nano-cellulose solution, and then the potassium bromide solution was added.
6. The method of claim 1, wherein, In step (2), after adding the silver nitrate solution and the potassium bromide solution, the pH value was not adjusted and the reaction was directly carried out at room temperature with stirring, or the pH value of the system was adjusted to 3.0~5.2 using dilute nitric acid and / or ethylenediamine before the reaction was carried out at room temperature with stirring.
7. The method of claim 1, wherein, In step (2), the reaction was carried out at room temperature with stirring for 2-3h.
8. The method of claim 1, wherein, In step (2), filtration or centrifugation was used for solid-liquid separation, and the solid after solid-liquid separation was washed with water and ethanol for multiple times, and then dried at a temperature of 60-80℃ for 6-18h after washing.