Preparation method and application of N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst

Abstract

The present invention is a preparation method and application of N-Carbon@Ag-void@SiO2 egg yolk-eggshell structure nanocatalyst. The method first prepares 3-aminophenol formaldehyde resin microspheres@SiO2 core-shell structure nanoparticles, and then, the Ag in the medium + Through the SiO2 shell, it contacts with the amino groups on the surface of 3-APF and converts Ag into + The Ag nanoparticles are then in situ reduced to Ag nanoparticles and fixed to the 3-APF surface. Finally, the Ag-loaded 3-APF@Ag@SiO2 core-shell nanoparticles are carbonized. Due to the coordination between the Ag nanoparticles and the nitrogen atoms on the core, the Ag nanoparticles migrate as the core shrinks during carbonization, ultimately forming the N-Carbon@Ag-void@SiO2 yolk-eggshell nanocatalyst. This method eliminates the complex template removal process, resulting in a simple, low-cost method suitable for large-scale preparation.

Description

Technical Field

[0001] The present invention belongs to the field of catalysis, and specifically relates to a preparation method and application of an N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst. Background Art

[0002] Yolk-eggshell nanoparticles have attracted attention from researchers in the field of catalysis due to their unique structural features: a mesoporous shell, a cavity of adjustable size, and a removable core. By encapsulating precious metal nanoparticles within the shell, this structure solves the problem of agglomeration of precious metal nanoparticles during catalysis and improves the reuse rate of precious metals. Furthermore, the presence of the cavity makes the environment surrounding the precious metal nanoparticles relatively uniform, exposing more active sites during the catalytic process and thus improving their catalytic efficiency. Building on the advantages of yolk-eggshell catalysts in the catalytic field, by loading smaller precious metal nanoparticles onto the core / shell of this structure, more catalytic active sites can be exposed while retaining the advantages of the yolk-eggshell structure as a catalyst, thereby improving the utilization rate of precious metals and enhancing their catalytic activity.

[0003] Currently, yolk-eggshell nanocatalysts are typically coated layer by layer, followed by dissolution or calcination to remove the template to create a cavity, thereby preparing yolk-eggshell nanoparticle catalysts. Chinese patent CN 110405200 A discloses a method for preparing Au@hollow carbon nanocomposite nanoparticles. Using SiO2 as a sacrificial template, SiO2 is first coated on Au nanoparticles, followed by coating the composite particles with a polychloromethylstyrene complex. Carbonization and removal of the SiO2 template are then performed to obtain the Au@hollow carbon nanocomposite. To improve the utilization rate of precious metals, Chen Zhe et al. used carbon nanoparticles as templates to prepare a Pd@SiO2 nanoparticle catalyst with a precious metal loaded on the shell (Chem. Comm. 46 (2010) 6524-6526). First, Pd nanoparticles are loaded on carbon nanoparticles, then coated with a silica shell. Finally, calcination is performed to remove the core, resulting in a Pd@SiO2 nanoreactor with a shell loaded with precious metals. In the preparation of egg yolk-eggshell nanocatalysts, the use of sacrificial templates undoubtedly leads to drawbacks such as complex preparation processes and high costs. Therefore, it is of great research significance to develop a simple and low-cost method for preparing egg yolk-eggshell nanocatalysts. Summary of the Invention

[0004] The purpose of the present invention is to address the shortcomings of the current technology and provide a preparation method and application of N-Carbon@Ag-void@SiO2 egg yolk-eggshell structure nanocatalyst. The method first prepares 3-aminophenol formaldehyde resin microspheres@SiO2 (3-APF@SiO2) core-shell structure nanoparticles. Then, the Ag in the medium + Through the SiO2 shell, it contacts with the amino groups on the surface of 3-APF and converts Ag into + In situ reduction to Ag nanoparticles and fixation on the surface of 3-APF. Finally, the Ag-loaded 3-APF@Ag@SiO2 core-shell structured nanoparticles were carbonized. Due to the coordination between the Ag nanoparticles and the nitrogen atoms on the core, they migrated as the core shrank during the carbonization process, eventually forming the N-Carbon@Ag-void@SiO2 yolk-eggshell structured nanocatalyst. This method eliminates the complex template removal process, is simple, low-cost, and suitable for large-scale preparation. The N-Carbon@Ag-void@SiO2 yolk-eggshell structured nanocatalyst was applied to the catalytic degradation of p-nitrophenol, which could be completely degraded in 22 minutes, with a corresponding catalyst turnover frequency (TOF) of 137.1 / h.

[0005] The technical solution of the present invention is:

[0006] A method for preparing an N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst, the method comprising the following steps:

[0007] The material composition and proportion are as follows:

[0008]

[0009] Step (1): According to the above raw material ratio, 3-aminophenol is dissolved in a mixed solution of distilled water, anhydrous ethanol, and ammonia water, and formaldehyde is added to react for 0.5 to 1.5 hours to prepare 3-aminophenol formaldehyde resin microspheres (3-APF). Then, CTAB is added to the system and stirred for 5 to 15 minutes, and then TEOS is added and the reaction is continued for 20 to 30 hours to obtain 3-APF@SiO2 core-shell structure nanoparticle emulsion;

[0010] Step (2): hydrothermally reacting the obtained 3-APF@SiO2 core-shell structure nanoparticle emulsion at 100-130°C for 0.5-24 hours; after cooling to room temperature, adding an ethanol solution of AgNO3, magnetically stirring, and reacting at room temperature for 6-10 hours; and centrifugally separating to obtain 3-APF@Ag@SiO2 core-shell structure nanoparticles;

[0011] Step (3): The obtained 3-APF@Ag@SiO2 core-shell structured nanoparticles are carbonized at 500-550°C for 2-4h to obtain N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalysts.

[0012] The mass concentration range of the AgNO3 ethanol solution is 0.01-0.03%;

[0013] The mass concentration of the ammonia water is 25-30%;

[0014] The mass concentration of the formaldehyde solution is 30-40%.

[0015] In step (1), the stirring rate is 230-300 rpm and the reaction temperature is 35-40°C;

[0016] The diameter of N-Carbon-void@SiO2 egg yolk-eggshell structured nanoparticles is 389-538nm.

[0017] The particle size of Ag nanoparticles in N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanoparticles is 8-25nm.

[0018] The shell material thickness of N-Carbon@Ag-void@SiO2 egg yolk-eggshell structure nanoparticles is 30-42nm.

[0019] The N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst prepared by the above preparation method is used to catalyze the degradation of p-nitrophenol under the condition of NaBH4 as a reducing agent.

[0020] The essential features of the present invention are:

[0021] The present invention breaks the traditional method of preparing yolk-eggshell structured nanoparticle catalysts by first coating layer by layer and then removing the template, and provides a method for preparing yolk-eggshell nanocatalysts by loading precious metals using the "ship-building in a bottle" thinking (i.e., first preparing core-shell structured nanoparticles and then loading the metal on the core part).

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention utilizes the idea of ​​"building a ship in a bottle" to load Ag nanoparticles to prepare N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst, which has the advantages of simple process, low cost, high yield, and is easy to mass produce;

[0024] (2) The N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanoparticles prepared by the preparation method provided by the present invention exhibit the characteristics of uniform particle size (PDI = 0.298), adjustable particle size (415-610nm), and high Ag loading (0.805%), and have good application prospects in the field of catalysis;

[0025] (3) Based on its structural advantages, the N-Carbon@Ag-void@SiO2 yolk-eggshell nanocatalyst prepared in this invention maximizes the utilization of precious metals and provides excellent recycling stability. The catalyst exhibits excellent catalytic performance in the catalytic degradation of p-nitrophenol (TOF = 137.1 / h). BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of the preparation of N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst in Example 1.

[0027] Figure 2 TEM photo of 3-APF@Ag@SiO2 core-shell structured nanoparticles prepared in Example 1.

[0028] Figure 3 This is the SEM photo of the N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst prepared in Example 1.

[0029] Figure 4 XRD pattern of N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst prepared in Example 1.

[0030] Figure 5 SEM photos of N-Carbon-void@SiO2 egg yolk-eggshell structures prepared in Examples 2-5 with 0.5 g, 0.6 g, 0.7 g, and 0.8 g of 3-aminophenol added, respectively.

[0031] Figure 6 TEM photos of N-Carbon-void@SiO2 yolk-shell structures prepared in Examples 2-5 with 0.5 g, 0.6 g, 0.7 g, and 0.8 g of 3-aminophenol added, respectively.

[0032] Figure 7 This is a SEM photograph of the sample prepared in Example 6 without adding CTAB.

[0033] Figure 8 This is an SEM photograph of the sample prepared in Example 7 without the participation of ammonia water in the coating process.

[0034] Figure 9 This is a TEM photograph of Example 8 that failed to successfully load Ag nanoparticles.

[0035] Figure 10 The time-dependent UV absorption spectrum of the N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst prepared in Example 1 catalyzing the degradation of p-nitrophenol to produce p-aminophenol.

[0036] Figure 11 This is a diagram showing the effect of the cyclic application of the N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst prepared in Example 1 to degrade p-nitrophenol into p-aminophenol. DETAILED DESCRIPTION

[0037] Example 1.

[0038] (1) 0.7 g of 3-aminophenol was ultrasonically dissolved in a mixed solution of 15.79 g of anhydrous ethanol, 45.00 g of distilled water and 0.18 g of ammonia water (28 wt%). At a reaction temperature of 35 ° C and a rotation speed of 300 rpm, 0.73 g of formaldehyde solution (37 wt%) was added and reacted for 1 h to prepare 3-APF. Then, 0.51 g of CTAB was added to the system and stirred for 10 min. After that, 2.36 g of TEOS was added and the reaction was continued for 24 h to obtain 3-APF@SiO2 core-shell structure nanoparticle emulsion (67.7 mL).

[0039] (2) 19.13 g (20 mL) of 3-APF@SiO2 core-shell structure nanoparticle emulsion was reacted in a polytetrafluoroethylene-lined hydrothermal reactor at 130°C for 24 h. After cooling to room temperature, 15.79 g of 0.02% silver nitrate ethanol solution was added thereto. The mixture was stirred magnetically at room temperature for 8 h. After centrifugation, 3-APF@Ag@SiO2 core-shell structure nanoparticles with Ag core loading were obtained. TEM test was performed on the sample at this time, see Figure 2 It can be clearly seen in the figure that Ag nanoparticles are loaded on the core of the core-shell structure.

[0040] (3) 3-APF@Ag@SiO2 core-shell structured nanoparticles were carbonized at 550℃ for 2h in a tube furnace to obtain N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalysts. The prepared samples were subjected to TEM and XRD tests, see Figure 3 and Figure 4 It can be clearly seen in the figure that the nanoparticles are evenly loaded on the core of the yolk-eggshell structure, and the loaded nanoparticles are Ag nanoparticles.

[0041] The process flow chart of the above preparation process is shown in Figure 1 .

[0042] Example 2.

[0043] (1) 0.5 g of 3-aminophenol was ultrasonically dissolved in a mixed solution of 15.79 g of anhydrous ethanol, 45.00 g of distilled water and 0.18 g of ammonia water (28 wt%). At a reaction temperature of 35 ° C and a rotation speed of 300 rpm, 0.73 g of formaldehyde solution (37 wt%) was added and reacted for 1 h to prepare 3-APF. Then, 0.51 g of CTAB was added to the system and stirred for 10 min. After that, 2.36 g of TEOS was added and the reaction was continued for 24 h to obtain 3-APF@SiO2 core-shell structure nanoparticle emulsion.

[0044] (2) 19.07 g of 3-APF@SiO2 core-shell structured nanoparticle emulsion was reacted in a polytetrafluoroethylene-lined hydrothermal reactor at 130°C for 24 h, and solidified 3-APF@SiO2 core-shell structured nanoparticles were obtained after centrifugal separation.

[0045] (3) The solidified 3-APF@SiO2 core-shell structured nanoparticles were carbonized at 550 °C in a tube furnace for 2 h to obtain N-Carbon-void@SiO2 yolk-eggshell structured nanoparticles.

[0046] Example 3.

[0047] (1) 0.6 g of 3-aminophenol was ultrasonically dissolved in a mixed solution of 15.79 g of anhydrous ethanol, 45.00 g of distilled water and 0.18 g of ammonia water (28 wt%). At a reaction temperature of 35 ° C and a rotation speed of 300 rpm, 0.73 g of formaldehyde solution (37 wt%) was added and reacted for 1 h to prepare 3-APF. Then, 0.51 g of CTAB was added to the system and stirred for 10 min. After that, 2.36 g of TEOS was added and the reaction was continued for 24 h to obtain 3-APF@SiO2 core-shell structure nanoparticle emulsion.

[0048] (2) 19.09 g of 3-APF@SiO2 core-shell structured nanoparticle emulsion was reacted in a polytetrafluoroethylene-lined hydrothermal reactor at 130°C for 24 h, and solidified 3-APF@SiO2 core-shell structured nanoparticles were obtained after centrifugal separation.

[0049] (3) The solidified 3-APF@SiO2 core-shell structured nanoparticles were carbonized at 550 °C in a tube furnace for 2 h to obtain N-Carbon-void@SiO2 yolk-eggshell structured nanoparticles.

[0050] Example 4.

[0051] (1) 0.7 g of 3-aminophenol was ultrasonically dissolved in a mixed solution of 15.79 g of anhydrous ethanol, 45.00 g of distilled water and 0.18 g of ammonia water (28 wt%). At a reaction temperature of 35 ° C and a rotation speed of 300 rpm, 0.73 g of formaldehyde solution (37 wt%) was added and reacted for 1 h to prepare 3-APF. Then, 0.51 g of CTAB was added to the system and stirred for 10 min. After that, 2.36 g of TEOS was added and the reaction was continued for 24 h to obtain 3-APF@SiO2 core-shell structure nanoparticle emulsion.

[0052] (2) 19.13 g of 3-APF@SiO2 core-shell structured nanoparticle emulsion was reacted in a polytetrafluoroethylene-lined hydrothermal reactor at 130°C for 24 h, and solidified 3-APF@SiO2 core-shell structured nanoparticles were obtained after centrifugal separation.

[0053] (3) The solidified 3-APF@SiO2 core-shell structured nanoparticles were carbonized at 550 °C in a tube furnace for 2 h to obtain N-Carbon-void@SiO2 yolk-eggshell structured nanoparticles.

[0054] Example 5.

[0055] (1) 0.8 g of 3-aminophenol was ultrasonically dissolved in a mixed solution of 15.79 g of anhydrous ethanol, 45.00 g of distilled water and 0.18 g of ammonia water (28 wt%). At a reaction temperature of 35 ° C and a rotation speed of 300 rpm, 0.73 g of formaldehyde solution (37 wt%) was added and reacted for 1 h to prepare 3-APF. Then, 0.51 g of CTAB was added to the system and stirred for 10 min. After that, 2.36 g of TEOS was added and the reaction was continued for 24 h to obtain 3-APF@SiO2 core-shell structure nanoparticle emulsion.

[0056] (2) 19.14 g of 3-APF@SiO2 core-shell structured nanoparticle emulsion was reacted in a polytetrafluoroethylene-lined hydrothermal reactor at 130°C for 24 h, and solidified 3-APF@SiO2 core-shell structured nanoparticles were obtained after centrifugal separation.

[0057] (3) The solidified 3-APF@SiO2 core-shell structured nanoparticles were carbonized at 550 °C in a tube furnace for 2 h to obtain N-Carbon-void@SiO2 yolk-eggshell structured nanoparticles.

[0058] The samples obtained in Example 2-5 were subjected to SEM and TEM tests:

[0059] SEM images of the samples can be found at Figure 5 , TEM photos see Figure 6By varying the amount of 3-aminophenol added, the prepared egg yolk-shell nanoparticles exhibited a uniform hollow spherical shape. Furthermore, increasing the amount of 3-aminobenzene added increased the particle size of the prepared N-Carbon-void@SiO2 egg yolk-shell nanoparticles (389 to 538 nm). Therefore, varying the amount of 3-aminophenol added allows the preparation of N-Carbon@Ag-void@SiO2 egg yolk-shell nanocatalysts of varying particle sizes.

[0060] Comparative Example 1.

[0061] The difference from Example 4 is that CTAB is not added in this example.

[0062] 0.7g of 3-aminophenol was ultrasonically dissolved in a mixed solution of 15.79g of anhydrous ethanol, 45.00g of distilled water, and 0.18g of ammonia water (28wt%). 3-APF was prepared by adding 0.73g of formaldehyde solution (37wt%) at a reaction temperature of 35°C and a rotation speed of 300rpm for 1h. 2.36g of TEOS was then added to the system and the reaction continued for 24h. The obtained sample was subjected to SEM testing. SEM photos are shown in Figure 7 The results show that when CTAB is not added, only some silica particles are deposited on 3-APF, and it cannot completely coat it. This phenomenon occurs mainly because in the silica-coated 3-APF experiment, CTAB self-assembles on the 3-APF surface, with the hydrophobic end extending toward 3-APF and the amino group (i.e., the hydrophilic end) extending toward the reaction medium. As a result, the surface of 3-APF has a positive charge, which attracts the negatively charged silica to nucleate and grow on its surface, forming completely coated 3-APF@SiO2 core-shell structured nanoparticles.

[0063] Comparative Example 2.

[0064] The difference from Example 4 is that no ammonia water is involved when the silica coats 3-APF.

[0065] (1) 0.7 g of 3-aminophenol was ultrasonically dissolved in a mixed solution of 15.79 g of anhydrous ethanol, 45.00 g of distilled water, and 0.18 g of ammonia water (28 wt%). At a reaction temperature of 35 ° C and a rotation speed of 300 rpm, 0.73 g of formaldehyde solution (37 wt%) was added and reacted for 1 h to prepare a 3-APF nanoparticle emulsion.

[0066] (2) The obtained 3-APF nanoparticle emulsion was centrifuged (8000 rpm), washed with a 1:1 mixture of water and ethanol, and then redispersed in a mixture of 15.79 g of anhydrous ethanol and 45.00 g of distilled water. 0.51 g of CTAB was added to the system and stirred for 10 min. 2.36 g of TEOS was then added and reacted for 24 h. The prepared sample was subjected to SEM testing. The SEM photos are shown in FIG. Figure 8 The results show that in the silica-coated 3-APF experiment, without the addition of ammonia, most of the silica nucleated in the medium, with some depositing on the 3-APF surface. This is mainly because during the silica-coated 3-APF process, the ammonium ions released by the ammonia adsorbed on the 3-APF surface, attracting the negatively charged silica to nucleate and grow on it. Without the addition of ammonia, the silica could not be completely deposited on the 3-APF surface, resulting in incomplete coating.

[0067] From Example 4, Comparative Example 1 and Comparative Example 2, we can see that the mutual attraction between the positive charge on 3-APF and the negative charge on silica is the main reason for the successful preparation of 3-APF@SiO2 core-shell structured nanoparticles.

[0068] Comparative Example 3.

[0069] The difference from Example 1 is that the 3-APF@SiO2 core-shell structure nanoparticles prepared in step (1) are not subjected to high-temperature hydrothermal treatment and are directly loaded with Ag.

[0070] (1) 0.7 g of 3-aminophenol was ultrasonically dissolved in a mixed solution of 15.79 g of anhydrous ethanol, 45.00 g of distilled water and 0.18 g of ammonia water (28 wt%). At a reaction temperature of 35 ° C and a rotation speed of 300 rpm, 0.73 g of formaldehyde solution (37 wt%) was added and reacted for 1 h to prepare 3-APF. Then, 0.51 g of CTAB was added to the system and stirred for 10 min. After that, 2.36 g of TEOS was added and the reaction was continued for 24 h to obtain 3-APF@SiO2 core-shell structure nanoparticle emulsion.

[0071] (2) Add 15.79 g of 0.02% silver nitrate ethanol solution to 19.13 g of 3-APF@SiO2 core-shell structure nanoparticle emulsion and stir under magnetic stirring at room temperature for 8 h. TEM test of the sample was performed at this time, see Figure 9. At this time, the Ag nanoparticles failed to be successfully loaded between the core and shell of the 3-APF@SiO2 core-shell structure composite particles. The occurrence of this phenomenon is mainly because in the 3-APF@SiO2 core-shell nanoparticles that have not undergone hydrothermal treatment, the core and the shell are closely fitted together, and there is no position for the Ag nanoparticles to be loaded. However, the 3-APF@SiO2 core-shell structure nanoparticles that have undergone hydrothermal treatment will have small pits on the core surface, and this structure provides a position for the loading of Ag. Therefore, hydrothermal treatment is the main reason for the successful loading of Ag nanoparticles on the surface of the core of the 3-APF@SiO2 core-shell structure.

[0072] Example 9.

[0073] The catalytic reduction reaction of p-nitrophenol was used as a model reaction to evaluate the performance of the N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst prepared in Example 1. 0.3mL of a 0.2mol / L freshly prepared NaBH4 solution was added to a mixed solution of 0.3mL of a 0.01mol / L p-nitrophenol solution and 3ml of deionized water. 0.2mL of an aqueous solution of N-Carbon@Ag-void@SiO2 with a mass fraction of 0.04% was added at room temperature. The degradation process was monitored by an ultraviolet spectrophotometer (the absorbance of the reaction system at 402nm was tested every 2min). The results showed that the catalyst could completely degrade p-nitrophenol in 22min, and the corresponding catalytic degradation process was as follows: Figure 10 The yolk-eggshell catalyst was separated by centrifugation and its cyclic catalytic performance was tested. Figure 11 As shown, the catalytic degradation effect can still be maintained above 90% after five times.

[0074] The catalyst showed excellent catalytic performance in the catalytic degradation of p-nitrophenol (TOF = 137.1 / h). The comparison of the catalytic effect of different Ag-based catalysts on the reduction of p-nitrophenol is shown in Table 1.

[0075] Table 1 Comparison of catalytic effects of different Ag-based catalysts on the reduction of p-nitrophenol

[0076]

[0077] The above examples demonstrate that varying the amount of 3-aminophenol added can yield yolk-shell composite particles of varying particle sizes. Furthermore, the presence of mesopores in the 3-APF@SiO2 shell and amino groups on the core are key factors in enabling in-situ loading of Ag nanoparticles onto the core.

[0078] In summary, the present invention provides a method for preparing N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalysts. The resulting egg yolk-eggshell nanoparticles have adjustable particle size, can stably load Ag, and can efficiently catalyze the degradation of p-nitrophenol. The catalyst preparation method is simple and low-cost, with promising large-scale industrial applications. It is expected to be applied to a variety of chemical reactions in the catalysis field and provides new methods and ideas for preparing catalysts with novel structures.

[0079] Matters not covered by the present invention are known technologies.

Claims

1. A method for preparing N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst. The method is characterized in that it comprises the following steps: The raw material composition and proportion are as follows: ， Step (1): According to the above raw material ratio, 3-aminophenol is dissolved in a mixed solution of distilled water, anhydrous ethanol and ammonia water, and formaldehyde solution is added to react for 0.5 to 1.5 hours to prepare 3-aminophenol formaldehyde resin microspheres 3-APF, and then hexadecyltrimethylammonium bromide is added to the system and stirred for 5 to 15 minutes, and then tetraethyl silicate is added and the reaction is continued for 20 to 30 hours to obtain 3-APF@SiO2 core-shell structure nanoparticle emulsion; Step (2): The obtained 3-APF@SiO2 core-shell structure nanoparticle emulsion is subjected to a hydrothermal reaction at 100-130°C for 0.5-24 h, and after cooling to room temperature, an ethanol solution of AgNO3 is added according to the above raw material ratio, and the mixture is stirred magnetically and reacted at room temperature for 6-10 h; 3-APF@Ag@SiO2 core-shell structure nanoparticles are obtained after centrifugal separation; Step (3): The obtained 3-APF@Ag@SiO2 core-shell structured nanoparticles are carbonized at 500-550°C for 2-4 hours to obtain N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalysts; In step (1), the stirring rate is 230-300 rpm and the reaction temperature is 35-40°C; The mass concentration range of the AgNO3 ethanol solution is 0.01~0.03%; The mass concentration of the ammonia water is 25-30%; The mass concentration of the formaldehyde solution is 30-40%.

2. The method for preparing the N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanocatalyst according to claim 1, wherein the diameter of the N-Carbon-void@SiO2 egg yolk-eggshell structured nanoparticles is 389-538 nm; The particle size of Ag nanoparticles in N-Carbon@Ag-void@SiO2 egg yolk-eggshell structured nanoparticles is 8-25 nm; The shell material thickness of N-Carbon@Ag-void@SiO2 yolk-eggshell structured nanoparticles is 30-42 nm.

3. The use of the N-Carbon@Ag-void@SiO2 egg yolk-eggshell structure nanocatalyst prepared by the method according to claim 1, characterized in that it is used to achieve catalytic degradation of p-nitrophenol under the condition of NaBH4 as a reducing agent.

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