Three-dimensional silver-based composite aerogel, preparation method and application thereof

Abstract

The present application relates to the technical field of three-dimensional composite materials, and particularly relates to a three-dimensional silver-based composite aerogel as well as a preparation method and application thereof. After a cross-linking reaction between a poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel prepared by an ultraviolet light polymerization method and calcium chloride, a poly(acrylamide-co-acrylic acid) / sodium alginate aerogel is prepared by a freeze-drying method, a poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel is prepared by a sintering method, and a three-dimensional silver-based composite aerogel with high specific surface area and high catalytic activity is prepared by an in-situ deposition method using silver nitrate as a precursor solution. A three-dimensional hydrogen peroxide sensor prepared by using the aerogel as a working electrode can realize rapid and accurate detection of hydrogen peroxide. Through a cyclic voltammetry (CV) module of an electrochemical workstation, the detection limit of the hydrogen peroxide sensor is 0.1 muM, and the hydrogen peroxide sensor has a linear reaction in a range of 1-20000 muM.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional composite materials, and in particular to a three-dimensional silver-based composite aerogel and a preparation method and application thereof. Background Art

[0002] Hydrogen peroxide is an inorganic, volatile compound with strong oxidizing properties. It is commonly used as a chemical in bleaching solutions, water treatment, and chemical synthesis. It is also an important biomolecule involved in host defense, oxidative biosynthetic reactions, metabolism, oxidative stress, and signaling. In respiratory and body fluids, hydrogen peroxide concentrations can indicate metabolic disturbances associated with diabetes, lung disease, or other health conditions. According to food safety regulations reported by Food Standards Australia New Zealand, the concentration of hydrogen peroxide in the final product should be less than 147 μM. Ensuring that hydrogen peroxide levels are within safe limits is critical for health, safety, and the environment.

[0003] Existing methods for hydrogen peroxide detection primarily include titration, colorimetry, chromatography, and electrochemistry. Electrochemical sensors are favored due to their higher sensitivity and selectivity, cost-effectiveness, relatively short response time, and miniaturization capabilities. The key to electrochemical methods lies in increasing the catalytic sites and specific surface area of ​​the catalyst, enabling faster and more efficient catalysis of hydrogen peroxide, thereby increasing the catalytic current and enhancing the sensitivity and detection limit of electrochemical detection.

[0004] Aerogels are solid materials with a highly porous structure and an extremely large specific surface area. Due to their large surface area, aerogels provide numerous active sites, resulting in excellent catalytic performance in catalytic reactions. Studies have demonstrated that using aerogels as a carrier or support allows for the uniform dispersion and immobilization of catalyst particles, thereby enhancing catalytic activity. Currently, aerogel composites prepared by freeze-drying methods have demonstrated excellent repeatability, selectivity, stability, and catalytic activity for H2O2 sensing.

[0005] Silver nanoparticles possess a large surface area and a highly tunable surface structure, enabling them to exhibit exceptional catalytic activity in catalytic reactions. Studies have demonstrated that carriers loaded with silver nanoparticles can provide a larger surface area and increase contact between reactants and catalysts, thereby enhancing the efficiency of catalytic reactions. Currently, chemical reduction methods, which are widely used to prepare silver nanoparticles, allow for precise control of their morphology and size, thereby regulating the distribution of surface active sites and the rate of catalytic reactions.

[0006] Therefore, designing a three-dimensional silver-based aerogel with high specific surface area and high catalytic activity is of great significance for the detection of hydrogen peroxide. Summary of the Invention

[0007] In light of this, the present invention aims to provide a three-dimensional silver-based composite aerogel, its preparation method, and its application. The three-dimensional silver-based composite aerogel provided by the present invention exhibits a high specific surface area, high catalytic activity, and excellent selectivity and stability. Using this aerogel as a working electrode, a three-dimensional hydrogen peroxide sensor can achieve rapid and accurate detection of hydrogen peroxide. Using the cyclic voltammetry (CV) module of an electrochemical workstation, the hydrogen peroxide sensor demonstrated a detection limit of 0.1 μM, with a linear response within the range of 1–20,000 μM.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a method for preparing a three-dimensional silver-based composite aerogel, comprising the following steps:

[0010] Step 1): Mix sodium alginate and deionized water and stir for 6 to 48 hours to obtain a sodium alginate solution;

[0011] Step 2): The sodium alginate solution obtained in step 1 is mixed with acrylamide, acrylic acid, N,N-methylenebisacrylamide and ammonium persulfate, and then deionized water is added and stirred for 0.5 to 30 minutes to obtain a mixed solution; the mixed solution is transferred to a polytetrafluoroethylene template and irradiated under ultraviolet light for 1 to 60 minutes to obtain a poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel;

[0012] Step 3): Soaking the poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel in a beaker containing calcium chloride solution for a cross-linking reaction, the reaction time being 0.5 to 24 h;

[0013] Step 4): The cross-linked poly (acrylamide-co-acrylic acid) / sodium alginate hydrogel obtained in step 3) is removed from the beaker, washed with deionized water 3 to 5 times, placed in a freeze dryer for 24 to 72 hours, and then placed in a vacuum drying oven for 1 to 48 hours to obtain a poly (acrylamide-co-acrylic acid) / sodium alginate aerogel;

[0014] Step 5): placing the poly(acrylamide-co-acrylic acid) / sodium alginate aerogel in a forced air drying oven for heat treatment to obtain poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel; the heat treatment time is 1 to 24 hours, and the heat treatment temperature is 100 to 800°C.

[0015] Step 6): The poly (acrylamide-co-acrylic acid) / sodium alginate carbon aerogel is placed in deionized water for ultrasonic dispersion, and the ultrasonic dispersion time is 1 to 60 min; then sodium hydroxide and chloroacetic acid are added, stirred for 1 to 60 min, and the mixture is placed in an ultrasonic bath for reaction for 1 to 5 hours, and washed alternately with deionized water and anhydrous ethanol 3 to 5 times, and then placed in a blast drying oven for 1 to 24 hours, and the drying temperature is 30 to 100 ° C;

[0016] Step 7): The aerogel obtained in step 6) is placed in deionized water, silver nitrate solution is added, stirred for 1 to 60 minutes, and then formaldehyde aqueous solution is added, stirred for 1 to 60 minutes, and washed alternately with deionized water and anhydrous ethanol 3 to 5 times, and placed in a blast drying oven to dry to prepare a three-dimensional silver-based composite aerogel; the drying time is 1 to 24 hours, and the drying temperature is 30 to 100°C.

[0017] Preferably, in step 1), the mass volume ratio of sodium alginate to deionized water is (10-50):1 mg / mL.

[0018] Preferably, in step 2), the mass ratio of the sodium alginate solution, acrylamide, acrylic acid, N,N-methylenebisacrylamide and ammonium persulfate is (5000-10000):(500-2000):(100-500):(1-10):(1-10); and the mass volume ratio of the total mass of the sodium alginate solution, acrylamide, acrylic acid, N,N-methylenebisacrylamide and ammonium persulfate to deionized water is (1-10):1 g / mL.

[0019] Preferably, the wavelength of the ultraviolet lamp in step 2) is 365 nm.

[0020] Preferably, in step 3), the mass ratio of poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel to calcium chloride is (100-1000):(1-10).

[0021] Preferably, in step 4), the processing temperature of the freeze dryer is -60°C, and the processing temperature of the vacuum drying oven is 37°C.

[0022] Preferably, in step 6), the mass volume ratio of poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel to deionized water is (100-500):1 mg / mL; the mass ratio of poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel, sodium hydroxide and chloroacetic acid is (10-50):(1-50):(1-50).

[0023] Preferably, in step 7), the mass volume ratio of aerogel to deionized water is (100-500):1 mg / mL; the volume ratio of deionized water, silver nitrate solution and formaldehyde aqueous solution is (10-50):(1-50):(1-50); and the concentration ratio of the silver nitrate solution to the formaldehyde aqueous solution is 1:(10-50)M.

[0024] The present invention also provides a three-dimensional hydrogen peroxide sensor, comprising a working electrode, an auxiliary electrode, a reference electrode and an electrolyte; the working electrode is a three-dimensional silver-based composite aerogel prepared by the above preparation method; the auxiliary electrode is a platinum sheet; the reference electrode is a saturated calomel electrode; and the electrolyte is a PBS buffer solution with a PBS concentration ≥0.01 M.

[0025] The present invention uses a poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel prepared by ultraviolet polymerization and then cross-linked with calcium chloride. The poly(acrylamide-co-acrylic acid) / sodium alginate aerogel is then freeze-dried. This is followed by a sintering process to prepare a poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel. Finally, an in-situ deposition method using silver nitrate as a precursor solution is used to prepare a three-dimensional silver-based composite aerogel with a high specific surface area and high catalytic activity. The preparation method provided by the present invention is low-cost, simple, and suitable for large-scale production for commercial applications.

[0026] A three-dimensional hydrogen peroxide sensor was prepared using the three-dimensional silver-based composite aerogel as a working electrode, which can achieve rapid and accurate detection of hydrogen peroxide. Through the cyclic voltammetry (CV) module of the electrochemical workstation, the detection limit of the hydrogen peroxide sensor was 0.1 μM, and it had a linear response in the range of at least 1 to 20,000 μM. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The CV curve is the peak value of the cyclic voltammetry response curve and the hydrogen peroxide concentration of the three-dimensional silver-based composite aerogel prepared by the present invention.

[0028] Figure 2 The graph is a linear fitting curve of the peak value of the cyclic voltammetry response curve of the three-dimensional silver-based composite aerogel prepared by the present invention and the logarithm of the hydrogen peroxide concentration. Implementation Method

[0029] The present invention provides a method for preparing a three-dimensional silver-based composite aerogel, comprising the following steps:

[0030] Step 1): Mix sodium alginate and deionized water and stir for 6 to 48 hours to obtain a sodium alginate solution;

[0031] Step 2): The sodium alginate solution obtained in step 1 is mixed with acrylamide, acrylic acid, N,N-methylenebisacrylamide, and ammonium persulfate, and then deionized water is added and stirred for 0.5 to 30 minutes to obtain a mixed solution; the mixed solution is transferred to a polytetrafluoroethylene template and irradiated under ultraviolet light for 1 to 60 minutes to obtain a poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel;

[0032] Step 3): Soaking the poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel in a beaker containing calcium chloride solution for a cross-linking reaction, the reaction time being 0.5 to 24 h;

[0033] Step 4): The cross-linked poly (acrylamide-co-acrylic acid) / sodium alginate hydrogel obtained in step 3) is removed from the beaker, washed with deionized water 3 to 5 times, placed in a freeze dryer for 24 to 72 hours, and then placed in a vacuum drying oven for 1 to 48 hours to obtain a poly (acrylamide-co-acrylic acid) / sodium alginate aerogel;

[0034] Step 5): placing the poly(acrylamide-co-acrylic acid) / sodium alginate aerogel in a forced air drying oven for heat treatment to obtain poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel; the heat treatment time is 1 to 24 hours, and the heat treatment temperature is 100 to 800°C.

[0035] Step 6): The poly (acrylamide-co-acrylic acid) / sodium alginate carbon aerogel is placed in deionized water for ultrasonic dispersion, and the ultrasonic dispersion time is 1 to 60 min; then sodium hydroxide and chloroacetic acid are added, stirred for 1 to 60 min, and the mixture is placed in an ultrasonic bath for reaction for 1 to 5 h, and washed alternately with deionized water and anhydrous ethanol 3 to 5 times, and then placed in a blast drying oven for 1 to 24 h, and the drying temperature is 30 to 100 ° C;

[0036] Step 7): The aerogel obtained in step 5 is placed in deionized water, silver nitrate solution is added, stirred for 1 to 60 minutes, and then formaldehyde aqueous solution is added, stirred for 1 to 60 minutes, and washed alternately with deionized water and anhydrous ethanol for 3 to 5 times, and placed in a blast drying oven for drying. The drying time is 1 to 24 hours and the drying temperature is 30 to 100 ° C to prepare a three-dimensional silver-based composite aerogel.

[0037] Unless otherwise specified, the present invention has no special requirements on the sources of the raw materials used, and commercially available products known to those skilled in the art can be used.

[0038] In the present invention, the stirring in step 1), step 2), step 6) and step 7) is all carried out at room temperature.

[0039] In the present invention, the mass volume ratio of sodium alginate and deionized water in step 1) is (10-50):1 mg / mL.

[0040] In the present invention, in step 2), the mass ratio of the sodium alginate solution, acrylamide, acrylic acid, N,N-methylenebisacrylamide, and ammonium persulfate is (5000-10000):(500-2000):(100-500):(1-10):(1-10); and the mass-to-volume ratio of the total mass of the sodium alginate solution, acrylamide, acrylic acid, N,N-methylenebisacrylamide, and ammonium persulfate to deionized water is (1-10):1 g / mL.

[0041] In the present invention, the wavelength of the ultraviolet lamp in step 2) is 365 nm.

[0042] In the present invention, the mass ratio of poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel to calcium chloride in step 3) is (100-1000):(1-10).

[0043] In the present invention, the processing temperature of the freeze dryer in step 4) is -60°C, and the processing temperature of the vacuum drying oven is 37°C.

[0044] In the present invention, in step 6), the mass volume ratio of poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel to deionized water is (100-500):1 mg / mL; the mass ratio of poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel, sodium hydroxide and chloroacetic acid is (10-50):(1-50):(1-50).

[0045] In the present invention, the mass volume ratio of aerogel to deionized water in step 7) is (100-500):1 mg / mL; the volume ratio of deionized water, silver nitrate solution and formaldehyde aqueous solution is (10-50):(1-50):(1-50); and the concentration ratio of the silver nitrate solution to the formaldehyde aqueous solution is 1:(10-50)M.

[0046] The present invention also provides a three-dimensional hydrogen peroxide sensor, comprising a working electrode, an auxiliary electrode, a reference electrode and an electrolyte; the working electrode is the three-dimensional silver-based composite aerogel prepared by the above preparation method; the auxiliary electrode is a platinum sheet; the reference electrode is a saturated calomel electrode; and the electrolyte is a PBS buffer solution with a PBS concentration of ≥0.01M.

[0047] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example

[0048] 0.2 g of sodium alginate was dissolved in 8 mL of water and stirred for 12 h. A 1 mL mixed solution containing 1.0 g of acrylamide, 0.2 g of acrylic acid, 0.0072 g of N,N-methylenebisacrylamide, and 0.0060 g of ammonium persulfate was prepared. The mixed solution was added to the sodium alginate solution and stirred for 3 min. After shaking, the mixture was transferred to a polytetrafluoroethylene template and irradiated under ultraviolet light for 10 min to obtain a poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel.

[0049] The obtained poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel was immersed in a centrifuge tube containing 40 mL of 0.5 mM calcium chloride solution and allowed to stand for 6 hours to fully cross-link. After the cross-linking was completed, the excess calcium chloride solution was poured out and the hydrogel was washed with deionized water three times. The hydrogel was freeze-dried at -60°C for 48 hours and vacuum-dried at 37°C for 12 hours to obtain poly(acrylamide-co-acrylic acid) / sodium alginate aerogel.

[0050] The obtained poly(acrylamide-co-acrylic acid) / sodium alginate aerogel was placed in a forced air drying oven for heat treatment at a temperature of 200 °C for 2 h to obtain poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel.

[0051] The obtained poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel was dispersed in 100 mL of deionized water and ultrasonically dispersed for 10 min. 5 g of sodium hydroxide and 5 g of chloroacetic acid were added and stirred for 2 min. The mixture was reacted in an ultrasonic bath for 2 h, washed alternately with deionized water and anhydrous ethanol three times, and placed in a forced air drying oven at 50 °C for 2 h to finally obtain a three-dimensional silver-based composite aerogel.

[0052] Electrochemical testing method of three-dimensional silver-based composite aerogel:

[0053] A three-electrode system was used, namely, a three-dimensional silver-based composite aerogel as the working electrode, a platinum sheet as the auxiliary electrode, and a saturated calomel as the reference electrode. 50 mL of 0.1 mM phosphate buffer solution was taken as the electrolyte. After connecting to an electrochemical workstation and using a cyclic voltammetry module, the detection limit was measured to be 5 μM, and a linear response was shown at least in the range of 10~6000 μM.

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a three-dimensional silver-based composite aerogel, characterized in that: The following steps are involved: Step 1): Mix sodium alginate and deionized water and stir for 6 to 48 hours to obtain a sodium alginate solution; Step 2): mixing the sodium alginate solution obtained in step 1) with acrylamide, acrylic acid, N,N-methylenebisacrylamide, and ammonium persulfate, adding deionized water, and stirring for 0.5 to 30 minutes to obtain a mixed solution; transferring the mixed solution to a polytetrafluoroethylene template, and irradiating the template under ultraviolet light for 1 to 60 minutes to obtain a poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel; Step 3): soaking the poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel in a beaker containing a calcium chloride solution to perform a cross-linking reaction for 0.5 to 24 hours; Step 4): The cross-linked poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel obtained in step 3) is removed from the beaker, washed with deionized water 3 to 5 times, placed in a freeze dryer for 24 to 72 hours, and then placed in a vacuum drying oven for 1 to 48 hours to obtain a poly(acrylamide-co-acrylic acid) / sodium alginate aerogel; Step 5): placing the poly(acrylamide-co-acrylic acid) / sodium alginate aerogel in a forced air drying oven for heat treatment to obtain a poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel; the heat treatment time is 1 to 24 hours, and the heat treatment temperature is 200 to 800° C.; Step 6): placing the poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel in deionized water for ultrasonic dispersion for 1 to 60 minutes; then adding sodium hydroxide and chloroacetic acid, stirring for 1 to 60 minutes, placing the mixture in an ultrasonic bath for reaction for 1 to 5 hours, washing it alternately with deionized water and anhydrous ethanol 3 to 5 times, and then drying it in a forced air drying oven for 1 to 24 hours at a drying temperature of 30 to 100° C.; Step 7): The aerogel obtained in step 6) is placed in deionized water, a silver nitrate solution is added, and the mixture is stirred for 1 to 60 minutes. Then, a formaldehyde solution is added and stirred for 1 to 60 minutes. The mixture is washed alternately with deionized water and anhydrous ethanol for 3 to 5 times, and dried in a forced air drying oven to prepare a three-dimensional silver-based composite aerogel. The drying time is 1 to 24 hours, and the drying temperature is 30 to 100° C.

2. The preparation method according to claim 1, characterized in that The mass volume ratio of sodium alginate and deionized water in step 1) is (10-50) mg / mL.

3. The preparation method according to claim 1, characterized in that In the step 2), the mass ratio of the sodium alginate solution, acrylamide, acrylic acid, N,N-methylenebisacrylamide and ammonium persulfate is (5000-10000):(500-2000):(100-500):(1-10):(1-10); the mass volume ratio of the total mass of the sodium alginate solution, acrylamide, acrylic acid, N,N-methylenebisacrylamide and ammonium persulfate to deionized water is (1-10) g / mL.

4. The preparation method according to claim 1, characterized in that The wavelength of the ultraviolet lamp in step 2) is 365 nm.

5. The preparation method according to claim 1, characterized in that In the step 3), the mass ratio of poly(acrylamide-co-acrylic acid) / sodium alginate hydrogel to calcium chloride is (100-1000):(1-10).

6. The preparation method according to claim 1, characterized in that In step 4), the processing temperature of the freeze dryer is -60°C, and the processing temperature of the vacuum drying oven is 37°C.

7. The preparation method according to claim 1, characterized in that In the step 6), the mass volume ratio of poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel to deionized water is (100-500) mg / mL; the mass ratio of the poly(acrylamide-co-acrylic acid) / sodium alginate carbon aerogel, sodium hydroxide and chloroacetic acid is (10-50):(1-50):(1-50).

8. The preparation method according to claim 1, characterized in that In step 7), the mass volume ratio of aerogel to deionized water is (100-500) mg / mL; the volume ratio of deionized water, silver nitrate solution and formaldehyde aqueous solution is (10-50):(1-50):(1-50); and the concentration ratio of the silver nitrate solution to the formaldehyde aqueous solution is 1:(10-50) mol / L.

9. A three-dimensional silver-based composite aerogel prepared according to the preparation method according to any one of claims 1 to 8.

10. A three-dimensional hydrogen peroxide sensor, characterized in that: The invention comprises a working electrode, an auxiliary electrode, a reference electrode and an electrolyte; the working electrode is a three-dimensional silver-based composite aerogel prepared by the preparation method according to any one of claims 1 to 8; the auxiliary electrode is a platinum sheet; the reference electrode is a saturated calomel electrode; and the electrolyte is a PBS buffer solution with a PBS concentration of ≥0.01M.

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