Preparation method of gold nanobipyramid surface localized silica coating based on iodide sub-monolayer mask

Abstract

This invention discloses a method for preparing gold nanobipyramidal surfaces with localized silica coating based on an iodide submonolayer mask. First, high-purity gold nanobipyramidal structures are obtained through seed growth and AgNO3-Ag selective etching. Then, NaI is introduced into a degassed CTAC solution to form a submonolayer adsorption mask on the gold surface, followed by gradient centrifugation purification. Finally, the mask-modified gold nanobipyramidal structures are reacted with a TEOS-ethanol solution in a weakly alkaline CTAB system, achieving precise silica deposition only in the uncovered end and waist regions. This invention combines atomic-level iodide submonolayer masking technology with a highly efficient purification process, achieving precise localization and patch uniformity of the silica coating area. Compared to traditional preparation methods, this significantly improves structural purity, controllability of the coating area, and experimental repeatability.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial synthesis technology, specifically to a method for preparing gold nanobipyramidal surface-localized silica coating based on an iodide sub-monolayer mask. Background Technology

[0002] Gold bipyramidal nanoparticles, as a class of highly anisotropic noble metal nanomaterials, possess broad application potential in fields such as optical metamaterials, controlled assembly, biosensing, and nanocatalysis due to their strong electromagnetic field enhancement effect at the tip region and tunable longitudinal localized surface plasmon resonance characteristics. Their performance largely depends on the controllability of surface functionalization methods. However, traditional methods such as chemical grafting, interface modulation, or solvent-induced methods struggle to achieve high-resolution, reproducible localized modification of nanoparticle surfaces, often resulting in problems such as uneven patch placement, large size deviations, and poor structural consistency.

[0003] On the other hand, the preparation of gold nanobipyramidal structures inevitably generates impurities such as nanorods and nanospheres. These impurities have similar surface chemical environments, making them difficult to completely separate using conventional centrifugation or elution methods. This significantly limits the purity, uniformity, and controllability of the final material's coating area. Furthermore, for systems requiring selective coating at the ends, waists, or specific plaque locations of gold nanobipyramidal structures, current technology lacks effective strategies to define reaction sites at the atomic scale.

[0004] In recent years, the construction of "atomic-level masks" utilizing the selective adsorption behavior of anionic ligands on gold surfaces has become a cutting-edge research direction in patchy nanoparticles. Iodides, in particular, can form adsorption layers on gold surfaces with a thickness approaching submonolayers and exhibit a significant blocking effect on subsequent reaction sites. Therefore, they hold promise for limiting the area where coating reactions occur, achieving true "localized functionalization." However, the construction of iodide masks still relies on high-purity, highly uniform gold bipyramidal nanoparticles as a substrate; otherwise, uneven mask coverage and differences in grafting interfaces will significantly reduce the patterning accuracy.

[0005] Therefore, there is an urgent need for an overall preparation strategy that combines efficient purification capabilities with atomic-level localized mask control to achieve precise silica coating of the ends and waist regions of gold nanoparticles, while ensuring high reproducibility, high uniformity and scalability of the structure. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing gold nanoparticles with localized silica coating based on an iodide sub-monolayer mask. Through efficient purification of gold nanoparticles, construction of the iodide sub-monolayer mask, and selective silica coating, precise coating of the tip and waist regions of the gold nanoparticles is achieved. This method features mild reaction conditions and high controllability, significantly improving the size uniformity and positional repeatability of the plaque region, and increasing the overall product purity, making it more suitable for high-performance applications such as metamaterial construction, targeted sensing, and interfacial catalysis.

[0007] This invention discloses a method for preparing gold nanobipyramidal surface localized silica coating based on an iodide submonolayer mask, comprising the following steps: S1: Preparation of crude gold nanobipyramidal product: S10: Mix CTAC, HAuCl4 and C6H5Na3O7 solution, add NaBH4 and ice water mixture, and shake well. S11: At a set temperature, the reaction was allowed to stand to obtain a gold nanoparticle bipyramidal seed solution; S12: Mix CTAB, HAuCl4, AgNO3 and HCl solution, shake well until transparent; S13: Add AA solution and the gold nanoparticle seed solution prepared in S10 to the mixed solution, and let it stand overnight at the set temperature to obtain crude gold nanoparticles. S2: Purification of gold nanobipyramidal particles: S20: The crude gold nanobipyramidal material obtained in S13 was dispersed in CTAC solution, AgNO3 solution and AA solution were added, and the reaction was carried out by stirring at a set temperature and then naturally cooled to room temperature to obtain Au@Ag nanorods. S21: After centrifuging the reaction solution, disperse the precipitate in a CTAB solution of a certain concentration and let it stand overnight; S22: Remove the supernatant, redisperse the precipitate in CTAB solution, add ammonia and H2O2 solution, allow the reaction to stand at the set temperature, and obtain purified gold nanobipyramidal particles after centrifugation and washing.

[0008] S3: Modification of iodide sub-monolayer masks: S30: The degassing process involves purging with nitrogen for 1 hour, then mixing 500 µL of 200 mM NaOH solution, 8.5 mL of degassed deionized water, and 1 mL of 100 mM NaI solution to prepare the NaI working solution; 0.9 mL to 1.4 mL of the NaI working solution is added dropwise to the gold nanoparticle bipyramidal dispersion, and the mixture is gently stirred at 300 rpm for 1 minute, then placed in a water bath at 25 ~ 35 ℃ and reacted in the dark for 20 ~ 35 minutes. S31: After repeated gradient centrifugation and washing, gold nanobipyramidal structures modified with iodide sub-monolayer masks were obtained; S4: Preparation of silica-localized gold nanobipyramidal nanoparticles: S40: The gold nanobipyramidal structure modified with the iodide sub-monolayer mask prepared in S31 was dispersed in CTAB solution and the pH was adjusted to weakly alkaline. S41: Add the TEOS ethanol solution quickly in one go at the set rotation speed; S42: Continue stirring the reaction slowly at the set temperature, and centrifuge and wash 2-3 times to obtain silica-localized gold nanobipyramidal nanoparticles.

[0009] Furthermore, in S13, the temperature is set to be controlled at 25 ~ 35 ℃, and the settling time is controlled at 10 ~ 12 hours.

[0010] Furthermore, in S20, the temperature is set to be controlled at 65~70℃, the stirring speed is 270 rpm, and the reaction time is controlled at 3~4 hours.

[0011] Furthermore: In S21, the centrifugation speed is 7000 rpm, and the settling time is controlled at 10 to 12 hours.

[0012] Furthermore, in S22, the temperature is set to be controlled at 25 ~ 35 ℃, and the static reaction time is controlled at 3 ~ 4 hours.

[0013] Furthermore, in S30, the degassing process involves nitrogen purging for 1 hour, a rotation speed of 300 rpm, a temperature setting of 25-35 ℃, and a settling reaction time of 20-35 minutes.

[0014] Furthermore, in S31, the cleaning method is to add deaerated deionized water for cleaning, with rotation speeds of 6000 rpm, 7500 rpm, and 5500 rpm, for 15 minutes each time.

[0015] Furthermore: In S40, the pH is adjusted to the range of 8.3 to 8.7 using 0.1 M NaOH.

[0016] Furthermore: In S41, the rotation speed is set to 1400 rpm; the volume ratio of TEOS to ethanol is 4:1; the volume ratio of gold nanoparticle biconical dispersion to TEOS-ethanol solution is preferably 100:1, and the volume ratio is controlled within the range of 80:1 to 150:1 depending on the particle size.

[0017] Furthermore: In S42, the temperature is set to be controlled at 25 ~ 35 ℃, the stirring reaction time is controlled at 40 ~ 48 hours, and the stirring speed is 400 rpm; the cleaning method is to add deaerated deionized water for cleaning, with the speeds being 6000 rpm, 4000 rpm, and 3500 rpm in sequence, for 10 minutes each time.

[0018] (1) The process conditions are mild and controllable, and easy to scale up: The entire process is based on wet chemical operation and does not rely on complex and expensive equipment; the reaction temperature is moderate, the solvent system is stable, and the operation steps are highly standardized, making it suitable for large-scale preparation and application.

[0019] (2) Atomic-level precise positioning of silica coating area is achieved: by constructing a sub-monolayer adsorption mask on the surface of gold nanobipyramidal by iodide, the hydrolytic deposition of TEOS in the mask area is selectively blocked, thereby achieving high-precision localized coating of silica in non-mask areas (such as the end and waist), the coating patch position is fixed, the size is uniform, and the repeatability is significantly improved.

[0020] (3) Combined with efficient purification process, the product structure purity and consistency are significantly improved: Au@Ag nanorod intermediate is used and silver layer is selectively etched by ammonia water-hydrogen peroxide to effectively remove morphological impurities such as nanorods and nanospheres, and obtain gold nanobipyramidal substrate with high purity and high morphological consistency, which lays the structural foundation for subsequent mask modification and localization coating.

[0021] (4) The coating structure has excellent stability and functional tunability: The obtained AuNBPs@SiO2 composite nanostructure has both the plasmonic resonance characteristics of gold nanobipyramids and the chemical stability of silica, showing good application potential in the fields of optical metamaterial construction, targeted biosensing, interfacial catalysis and controllable self-assembly.

[0022] (5) The method is highly versatile and the process parameters are flexible and adjustable: By adjusting the coverage of the iodide mask, the TEOS addition ratio and reaction conditions, the size and position of the coated patches can be further controlled to meet the customized needs of different application scenarios for the surface functions of nanostructures. Attached Figure Description

[0023] Figure 1 The ultraviolet-visible absorption spectrum of the crude gold nanobipyramidal material obtained in Example 1 is shown. Figure 2 This is a transmission electron microscope (TEM) image of the crude gold nanobipyramidal sample obtained in Example 1. Figure 3 The ultraviolet-visible absorption spectrum of the Au@Ag nanorods obtained in Example 1 is shown below. Figure 4The ultraviolet-visible absorption spectra of gold nanobipyramidal particles before and after purification obtained in Example 1 are shown. Figure 5 This is a transmission electron microscope (TEM) image of the purified gold nanobipyramidal nanoparticles obtained in Example 1. Figure 6 The image shows a transmission electron microscope (TEM) image of the localized coated AuNBPs@SiO2 obtained in Example 1. Figure 7 The image shows a transmission electron microscope (TEM) image of the fully coated AuNBPs@SiO2 obtained in Comparative Example 1. Figure 8 The image shows a transmission electron microscope (TEM) image of the abnormally coated AuNBPs@SiO2 obtained in Comparative Example 2. Detailed Implementation

[0024] The following provides further explanation of the structures involved in this invention and the technical terms used. These descriptions are merely illustrative of implementations of the invention and do not constitute any limitation on the invention.

[0025] This invention discloses a method for preparing gold nanobipyramidal surface localized silica coating based on an iodide submonolayer mask, comprising the following steps: S1: Preparation of crude gold nanobipyramidal product: S10: Mix hexadecyltrimethylammonium chloride (CTAC), chloroauric acid (HAuCl4) and sodium citrate (C6H5Na3O7) solution, add sodium borohydride (NaBH4) and ice water mixture, and shake well; S11: At a temperature of 80 ~ 90 ℃, allow the reaction to stand for 60 ~ 90 minutes to obtain a gold nanoparticle bipyramidal seed solution; S12: Mix hexadecyltrimethylammonium bromide (CTAB), tetrachloroauric acid (HAuCl4), silver nitrate (AgNO3), and hydrochloric acid (HCl) solution, and shake until transparent; S13: Add ascorbic acid (AA) solution and gold nanoparticle bipyramidal seed solution prepared in S10 to the mixed solution, and let it stand for 10 to 12 hours at 25 to 35 ℃ to obtain crude gold nanoparticle bipyramidal product.

[0026] S2: Purification of gold nanobipyramidal particles: S20: The crude gold nanobipyramidal particles obtained in S13 were dispersed in CTAC solution, AgNO3 solution and AA solution were added, and after shaking evenly, the mixture was placed in a water bath at 65-70 ℃ for 3-4 hours at a speed of 270 rpm and then naturally cooled to room temperature to obtain Au@Ag nanorods. S21: Centrifuge the obtained reaction solution at 7000 rpm for 10 minutes, disperse the precipitate in CTAB solution, and let it stand at room temperature for 10 to 12 hours; S22: Remove the supernatant, redisperse the precipitate in CTAB solution, add ammonia and H2O2 solution, let it stand for 3 to 4 hours at 25 to 35°C, and then centrifuge and wash to obtain purified gold nanobipyramidal nanoparticles.

[0027] S3: Modification of iodide sub-monolayer masks: S30: The CTAC solution was degassed by purging with nitrogen for 1 hour at a speed of 300 rpm. The purified gold nanobipyramidal particles obtained in S22 were dispersed in the degassed CTAC solution, NaI solution was added dropwise and stirred, and the reaction was allowed to proceed in the dark at 25-35 ℃ for 20-35 minutes. S31: The gold nanobipyramidal nanoparticles modified with iodide sub-monolayer mask were obtained by sequentially centrifuging and washing with deaerated deionized water at speeds of 6300 rpm, 7600 rpm and 5600 rpm for 15 minutes each time. S4: Preparation of silica-localized gold nanobipyramidal nanoparticles: S40: Disperse the gold nanobipyramidal modified by the iodide sub-monolayer mask prepared in S31 in CTAB solution, and adjust the pH to weakly alkaline using 0.1 M NaOH. The pH needs to be controlled in the range of 8.3 to 8.7, preferably around pH 8.5. S41: At a rotation speed of 1400 rpm, a tetraethyl orthosilicate (TEOS)-ethanol solution with a volume ratio of 4:1 is rapidly added to the gold nanoparticle bipyramidal dispersion in one go; the volume ratio of the gold nanoparticle bipyramidal dispersion to the TEOS-ethanol solution is preferably 100:1, and can be controlled within the range of 80:1 to 150:1 depending on the particle size.

[0028] S42: Continue the reaction at 25 ~ 35 ℃ with slow stirring at 400 rpm for 40 ~ 48 hours. Centrifuge and wash 2-3 times by adding deaerated deionized water at speeds of 6000 rpm, 4000 rpm, and 3500 rpm for 10 minutes each time to obtain silica-localized coated gold nanobipyramidal nanoparticles. Example 1

[0029] A1: Preparation of crude gold nanobipyramidal product: (1) Take 5 mL of 0.1 M CTAC solution, add 5 mL of 10 mM HAuCl4 solution, and then add 0.25 mL of 10 mM C6H5Na3O7 solution. Shake well. While maintaining a speed of 800 rpm, quickly inject 0.25 mL of 25 mM NaBH4 ice-water mixed solution. The solution instantly changes from light yellow to brown. After stirring for 1 minute, place it in a 90℃ water bath for 90 minutes and let it cool naturally to room temperature to obtain gold nanobipyramidal seed solution. (2) Take 20 mL of 0.1 M CTAB solution, 1 mL of 10 mM HAuCl4 solution, 0.2 mL of 10 mM AgNO3 solution, and 0.4 mL of 1 M HCl solution, and shake well. Add 0.16 mL of 0.1 M AA solution to the mixture, and shake well until the solution changes from yellow to colorless and transparent to obtain the gold nanoparticle bipyramidal growth solution; (3) Add 160 uL of gold nano bipyramidal seed solution to the growth solution, place it in a 30℃ water bath, and let it stand for 12 hours to obtain crude gold nano bipyramidal product.

[0030] B1: Purification of gold nanobipyramidal particles: (1) Take 20 mL of crude gold nanoparticle bipyramidal dispersion, centrifuge at 8000 rpm for 15 minutes, then disperse the precipitate in 15 mL of 0.08 M CTAC solution, add 3 mL of 20 mM AgNO3 solution and 1.5 mL of 20 mM AA solution in sequence, shake evenly, and react in a water bath at 65℃ for 4 hours at a speed of 270 rpm to obtain Au@Ag nanorods; (2) Centrifuge the obtained reaction solution at 7000 rpm for 10 minutes, disperse the precipitate in 15 mL of 0.175 M CTAB solution, and let it stand overnight at room temperature; (3) Remove the supernatant, redisperse the precipitate in 2.5 mL of 1 mM CTAB solution, add 2.5 mL of 25~28 wt% ammonia water and 0.2 mL of 0.1 M H2O2 solution, react in a water bath at 30℃ for 4 hours, take the supernatant, centrifuge at 7000 rpm for 15 minutes to obtain the purified gold nanobipyramidal precipitate.

[0031] C1: Preparation of iodide sub-monolayer masks: (1) The purified gold nanoparticle bipyramidal precipitate was dispersed in 2.5 mL of 20 mM degassed CTAC solution; (2) Take 500 µL of 200 mM NaOH solution, 8.5 mL of degassed deionized water, and 1 mL of 100 mM NaI solution and mix them evenly to prepare NaI working solution; add 1 mL of NaI working solution to the gold nano bipyramidal dispersion (the amount added can be controlled within the range of 0.9 mL to 1.4 mL depending on the particle size), stir gently at 300 rpm for 1 minute, and place in a 30℃ water bath to react in the dark for 30 minutes; (3) The gold nanobipyramidal particles were centrifuged and washed at speeds of 6300 rpm, 7600 rpm and 5600 rpm for 15 minutes each time. After each centrifugation, they were resuspended in deaerated deionized water to obtain gold nanobipyramidal particles modified with iodide sub-monolayer mask.

[0032] D1: Preparation of silica-localized gold nanobipyramidal nanoparticles: (1) The gold nanobipyramidal nanoparticles modified with iodide sub-monolayer mask were dispersed in 0.15 mM CTAB solution, and the pH was adjusted to 8.5 by slowly adding 0.1 M NaOH solution. TEOS-ethanol solution was added rapidly in one go at 1400 rpm; (2) Place it in a water bath at 30°C and continue to stir slowly at 400 rpm for 48 hours; (3) The gold nanobipyramidal particles were centrifuged and washed at speeds of 6000 rpm, 4000 rpm and 3500 rpm for 10 minutes each time. After each centrifugation, they were resuspended in deaerated deionized water to obtain silica-localized coated gold nanobipyramidal particles.

[0033] Figure 1 The ultraviolet-visible absorption spectrum of the crude gold nanobipyramidal material obtained in Example 1 is shown below. Figure 2 This is a transmission electron microscope (TEM) image of the crude gold nanobipyramidal sample obtained in Example 1. Figure 3 The ultraviolet-visible absorption spectrum of the Au@Ag nanorods obtained in Example 1 is shown below. Figure 4 The image shows the ultraviolet-visible absorption spectrum of the purified gold nanobipyramidal nanoparticles obtained in Example 1. Figure 5 This is a transmission electron microscope (TEM) image of the purified gold nanobipyramidal nanoparticles obtained in Example 1. Figure 6 This is a transmission electron microscope (TEM) image of the gold nanobipyramidal surface localized with silica obtained in Example 1.

[0034] Comparative Example 1: The difference between this comparative example and Example 1 is that NaI solution was not added; all other operations were completely consistent with Example 1. Following steps A1-B1 of Example 1, a high-purity gold nanorod CTAB dispersion was prepared; however, no NaI solution was added, and the pH of the gold nanorod CTAB dispersion was directly adjusted to 8.5 using 0.1M NaOH solution. Then, following step C1 of Example 1, the TEOS-ethanol solution was added, reacted, and washed to obtain the final AuNBPs@SiO2 product. Figure 7 The image shows a transmission electron microscope (TEM) image of the fully coated AuNBPs@SiO2 obtained in Comparative Example 1. Figure 7 The results show that a complete core-shell silica coating layer is formed on the surface of the gold nanorods, without end-oriented coating characteristics. This is because the lack of an iodide mask to block the reaction sites on the sides of the gold nanorods allows TEOS hydrolysis products to be uniformly deposited on the entire surface of the gold nanorods, further confirming the key role of the NaI-constructed sub-monolayer mask in directional coating.

[0035] Comparative Example 2: The difference between this comparative example and Example 1 is that the amount of NaI solution added is changed to 0.2 mL, while all other operations are completely consistent with Example 1. Following steps A1-B1 of Example 1, the preparation of a high-purity gold nanorod CTAB dispersion was completed; however, the amount of NaI solution added was changed to 0.2 mL, which is 1 / 5 of the amount of NaI used in Example 1. Then, following step C1 of Example 1, the pH was adjusted to weakly alkaline, TEOS-ethanol solution was added, the reaction was carried out, and washing was performed to obtain the final AuNBPs@SiO2 product. Figure 8 The image shows a transmission electron microscope (TEM) image of the abnormally coated AuNBPs@SiO2 obtained in Comparative Example 2. Figure 8 The results show that silica forms uneven, misaligned localized coatings on the sidewalls, exhibiting patchy defects or positional drift, and failing to achieve stable end and waist-level localized structures. This is because insufficient NaI dosage leads to reduced iodide mask coverage and incomplete shielding, allowing localized TEOS hydrolysis on the sidewalls to continue, resulting in random leakage in the coated areas and preventing the stable acquisition of localized coating structures.

[0036] Finally, it should be noted that the above embodiments are only used to help understand the method and core ideas of the present invention, and are not intended to limit it. 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 present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing gold nanobipyramidal surface-localized silica coating based on an iodide submonolayer mask, characterized in that: Includes the following steps: S1: Preparation of crude gold nanobipyramidal product: S10: Mix CTAC, HAuCl4 and C6H5Na3O7 solution, add NaBH4 and ice water mixture, and shake well. S11: At a set temperature, the reaction was allowed to stand to obtain a gold nanoparticle bipyramidal seed solution; S12: Mix CTAB, HAuCl4, AgNO3 and HCl solution, shake well until transparent; S13: Add AA solution and the gold nanoparticle seed solution prepared in S11 to the mixed solution, and let it stand overnight at the set temperature to obtain crude gold nanoparticles. S2: Purification of gold nanobipyramidal particles: S20: The crude gold nanobipyramidal material obtained in S13 was dispersed in CTAC solution, AgNO3 solution and AA solution were added, and the reaction was carried out by stirring at a set temperature and then naturally cooled to room temperature to obtain Au@Ag nanorods. S21: After centrifuging the naturally cooled reaction solution obtained in S20, disperse the precipitate in a CTAB solution of a certain concentration and let it stand overnight; S22: Remove the supernatant, redisperse the precipitate in CTAB solution, add ammonia and H2O2 solution, let it stand at the set temperature, and after centrifugation and washing, obtain the purified gold nanobipyramidal particles. S3: Modification of iodide sub-monolayer masks: S30: The purified gold nanobipyramidal particles obtained in S22 are dispersed in a degassed CTAC solution, NaI solution is added dropwise and stirred, and then the reaction is allowed to proceed in the dark at a set temperature. In S30, the degassing process involved purging with nitrogen for 1 hour. Then, 500 µL of 200 mM NaOH solution, 8.5 mL of degassed deionized water, and 1 mL of 100 mM NaI solution were mixed thoroughly to prepare the NaI working solution. 0.9 mL to 1.4 mL of the NaI working solution was added dropwise to the gold nanoparticle bipyramidal dispersion, and the mixture was gently stirred at 300 rpm for 1 minute. The mixture was then placed in a water bath at 25 ~ 35 ℃ and reacted in the dark for 20 ~ 35 minutes. S31: After repeated gradient centrifugation and washing, gold nanobipyramidal structures modified with iodide sub-monolayer masks were obtained; S4: Preparation of silica-localized gold nanobipyramidal nanoparticles: S40: The gold nanobipyramidal structure modified with the iodide sub-monolayer mask prepared in S31 was dispersed in CTAB solution and the pH was adjusted to weakly alkaline. S41: Add the TEOS ethanol solution quickly in one go at the set rotation speed; S42: Continue stirring the reaction slowly at the set temperature, and centrifuge and wash 2-3 times to obtain silica-localized gold nanobipyramidal nanoparticles.

2. The method for preparing iodide sub-monolayer mask based gold nanobipyramidal surface-localized silica coating according to claim 1, characterized in that: In S13, the temperature is set to 25 ~ 35 ℃, and the settling time is set to 10 ~ 12 hours.

3. The method for preparing iodide sub-monolayer mask based gold nanobipyramidal surface-localized silica coating according to claim 1, characterized in that: In S20, the temperature is set at 65-70℃, the stirring speed is 270 rpm, and the reaction time is controlled at 3-4 hours.

4. The method for preparing gold nanobipyramidal surface localized silica coating based on an iodide submonolayer mask according to claim 1, characterized in that: In S21, the centrifugation speed is 7000 rpm, and the settling time is controlled at 10 to 12 hours.

5. The method for preparing gold nanobipyramidal surface localized silica coating based on an iodide submonolayer mask according to claim 1, characterized in that: In S22, the temperature is set to be controlled between 25 and 35 ℃, and the static reaction time is controlled between 3 and 4 hours.

6. The method for preparing gold nanobipyramidal surface localized silica coating based on an iodide submonolayer mask according to claim 1, characterized in that: In S31, the cleaning method is to add deaerated deionized water for cleaning, with the rotation speeds being 6000 rpm, 7500 rpm, and 5500 rpm respectively, for 15 minutes each time.

7. The method for preparing gold nanobipyramidal surface localized silica coating based on an iodide submonolayer mask according to claim 1, characterized in that: In S40, the pH is adjusted to the range of 8.3 to 8.7 using 0.1 M NaOH.

8. The method for preparing gold nanobipyramidal surface localized silica coating based on an iodide submonolayer mask according to claim 1, characterized in that: In S41, the rotation speed is set to 1400 rpm; the volume ratio of TEOS to ethanol is 4:1; and the volume ratio of gold nanoparticle biconical dispersion to TEOS-ethanol solution is 100:

1.

9. The method for preparing gold nanobipyramidal surface localized silica coating based on an iodide submonolayer mask according to claim 1, characterized in that: In S41, the volume ratio of gold nanoparticle biconical dispersion to TEOS-ethanol solution is controlled within the range of 80:1 to 150:1, depending on the particle size.

10. The method for preparing gold nanobipyramidal surface-localized silica coating based on an iodide submonolayer mask according to claim 1, characterized in that: In S42, the temperature is set to 25 ~ 35 ℃, the stirring reaction time is set to 40 ~ 48 hours, and the stirring speed is 400 rpm. The cleaning method is to add deaerated deionized water for cleaning, with the speeds being 6000 rpm, 4000 rpm, and 3500 rpm in sequence, for 10 minutes each time.

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