Preparation method and application of gold-silver alloy with hollow cube structure

Abstract

The present invention discloses a preparation method and application of a gold-silver alloy with a hollow cubic structure, and relates to the technical field of nano gold-silver alloys. The main points of the technical solution are: based on a one-pot method and a step-by-step control method, silver chloride is used as a template, sodium citrate with good biocompatibility and a single reducing agent ascorbic acid are used to prepare a gold-silver alloy with a hollow cubic structure. The gold-silver alloy with a hollow cubic structure has excellent catalytic activity and can be applied to the field of catalysis. The preparation method of the present invention is simple, and the prepared hollow cubic gold-silver alloy structure has the characteristics of adjustable size and surface plasmon resonance peak position, and the gold-silver alloy with a hollow cubic structure has a relatively rapid mode catalytic reaction, which is conducive to its application in catalysts.

Description

Technical Field

[0001] The invention relates to the technical field of hollow gold-silver alloys, and more specifically, to a preparation method and application of a gold-silver alloy with a hollow cubic structure. Background Art

[0002] Generally, the preparation of nano-scale colloidal gold and colloidal silver is relatively easy to achieve by chemical reduction method, but there are still great difficulties for the controllable synthesis of hollow gold-silver alloy nanocube structures. The prior art still has great difficulties in preparing hollow gold-silver alloy nanocube structures with regular morphology and adjustable optical properties using silver chloride as a sacrificial template. There are also relatively few literature reports in this regard, and it is often necessary to add surfactants, etc., which hinders the further modification and application of hollow gold-silver alloy nanocube structures. Regarding hollow cubic gold-silver alloy structures, there are still relatively few reports. For example, Ryu et al. (DOI: 10.1021 / acsami.9b18364) prepared a nano-mesh structure of silver chloride wrapped in a multi-metal structure, but the preparation process is complicated and it is difficult to accurately control the particle size and optical properties of the hollow nanocube structure. In addition, the article reports that the alloy structure is prepared by silver chloride and chloroauric acid, and different concentrations of surface coating agent PVP are also needed to prepare different hollow multi-metal nanostructures respectively. Li et al. (ACS Appl. Mater. Interfaces 2018, 10, 32526-32535) prepared gold-silver alloy nanocubes based on a mixed solution of chloroauric acid and silver chloride by adding ascorbic acid for direct reduction, mainly based on the Galvani replacement reaction.

[0003] The method for preparing hollow gold-silver alloy nanoparticles with high SERS activity disclosed in patent CN108372314B is: prepare silver nanocubes by a polyol process, add a stabilizer PVP and a reducing agent ascorbic acid, and slowly add chloroauric acid to obtain a hollow cubic gold-silver alloy nanoparticle sol. However, the defect of the hollow gold-silver alloy nanoparticle preparation method in the prior art is that it is necessary to prepare nanosilver cubes first, the process is complicated, and an additional surface coating agent needs to be added.

[0004] The preparation method of hollow gold-silver alloy polyhedron disclosed in patent CN201711098009.0 is: prepare silver nanocubes by polyol process, add surfactant and chloroauric acid to obtain hollow cubic gold-silver alloy nanoparticle sol, but the defect of the preparation method of hollow gold-silver alloy nanoparticles in the prior art is that high temperature is required to prepare nanosilver solid first, the process is complicated, and additional surface coating agent is required. Therefore, the preparation of hollow cubic gold-silver alloy structure based on one-pot method and step-by-step control method is very innovative. However, there are few reports on the application of hollow cubic gold-silver alloy structure in the field of catalysis. In addition, this method does not use organic toxic and harmful reagents, is a green synthesis method, and provides new ideas for the green synthesis of micro-nanostructure materials.

[0005] Through the above analysis, the problems and defects of the prior art are as follows: there are relatively great difficulties in synthesizing hollow cubic gold-silver alloy structures with controllable morphology and adjustable performance in the prior art. For example, from the perspective of the synthesis process of the hollow cubic gold-silver alloy structure, the existing methods often require surfactants (and) or different reducing agents to achieve the preparation of the hollow cubic gold-silver alloy structure, and the size and optical properties of the synthesized hollow cubic gold-silver alloy structure are difficult to control. Another commonly used method is to first prepare a silver nanostructure with a certain morphology, and then prepare a hollow cubic gold-silver alloy structure based on the Galvani replacement reaction, and the process is relatively cumbersome. Therefore, in terms of the safety of the reagents used, the convenience of the synthesis process, and the effectiveness of the application, the hollow cubic gold-silver alloy structure prepared by the present invention has good innovations.

[0006] The difficulty of solving the above problems and defects is:

[0007] The synthesis of hollow cubic gold-silver alloy structure not only replaces the traditional preparation of nanosilver structure with the conveniently prepared silver chloride microstructure, but also requires controlling the morphology formation process of silver chloride and chloroauric acid. This technology is based on a one-pot method and adopts the step-by-step addition of sodium citrate, ascorbic acid and chloroauric acid to achieve the preparation of hollow cubic gold-silver alloy structure. It is not only an innovation in the new application of silver chloride microstructure, but also an innovation in the new method for preparing hollow cubic gold-silver alloy structure, and also an innovation in the catalytic application of hollow cubic gold-silver alloy structure.

[0008] The significance of solving the above problems and defects is:

[0009] The synthesis of hollow cubic gold-silver alloy structures solves the problem of traditional methods requiring the preparation of nanosilver structures first, expands the application of silver chloride in controllable functional nanostructures, and does not add other biologically toxic surface coating agents, laying the foundation for the application of hollow cubic gold-silver alloy structures and providing new ideas. Summary of the invention

[0010] The purpose of the present invention is to solve the above problems and provide a preparation method and application of a gold-silver alloy with a hollow cubic structure. The preparation method of the present invention is simple, and the size of the prepared gold-silver alloy with a hollow cubic structure can be controlled. Under different molar ratios of silver nitrate and chloroauric acid, the size of the gold-silver alloy with a hollow cubic structure can vary from 94 to 116 nm, and the surface plasmon resonance peak can vary from 600 to 740 nm, with a relatively wide controllable size and tunable range. Moreover, the gold-silver alloy with a hollow cubic structure has a very rapid mode catalytic reaction, which is conducive to its application in catalysts.

[0011] The above technical objectives of the present invention are achieved through the following technical solutions: a method for preparing a gold-silver alloy with a hollow cubic structure, based on a one-pot method and a step-by-step control method, using silver chloride as a template, sodium citrate with good biocompatibility and a single reducing agent, ascorbic acid, to prepare a gold-silver alloy with a hollow cubic structure.

[0012] The present invention is further configured as follows: the method for preparing the gold-silver alloy with a hollow cubic structure specifically comprises the following steps:

[0013] S1: Preparation of silver chloride microstructures;

[0014] S2: Preparation of silver chloride-gold composite structure;

[0015] S3: Preparation of gold-silver alloy with hollow cubic structure.

[0016] The present invention is further configured as follows:

[0017] Step S1: The specific steps of preparing the silver chloride microstructure are as follows: at room temperature, a proper amount of sodium chloride is added to a certain amount of diluted silver nitrate solution to prepare the silver chloride microstructure.

[0018] Further preferably, a 20 mM silver nitrate aqueous solution is prepared as a stock solution and a 2% sodium citrate solution is prepared for standby use; a 1 mM NaCl aqueous solution is prepared as a stock solution; at room temperature, 100 microliters of the 20 mM silver nitrate aqueous solution is diluted to 4.2 mL in a 20 mL sample bottle, 50 microliters of 2% sodium citrate is added, and then 5 mL of the 1 mM NaCl aqueous solution is added; and a slightly milky white mixed solution is shaken to obtain a silver chloride microstructure formed on the surface.

[0019] The present invention is further configured as follows:

[0020] The specific steps of preparing the silver chloride-gold composite structure in step S2 are as follows: a small amount of ascorbic acid and chloroauric acid are successively added to a mixed solution of silver nitrate and sodium chloride (i.e., the mixed solution in which the silver chloride microstructure is formed in S1) to form a silver chloride-gold composite structure with a preliminary cubic morphology.

[0021] Further preferably, 100 mM ascorbic acid and 1% chloroauric acid (24.5 mM) are prepared for use; 1 mM ascorbic acid is obtained by diluting 100 mM ascorbic acid 100 times; and 200 microliters of 1 mM ascorbic acid and 100 microliters of 1% chloroauric acid are successively added to a mixed solution of silver nitrate and sodium chloride (i.e., a mixed solution in which a silver chloride microstructure is formed in S1) to form a silver chloride-gold composite structure with a preliminary cubic morphology.

[0022] The present invention is further configured as follows:

[0023] The specific steps of step S3 for preparing the gold-silver alloy with a hollow cubic structure are as follows: a large amount of ascorbic acid is added as a reducing agent to the mixed solution of the silver chloride-gold composite structure synthesized in S2, and the mixture is shaken and allowed to stand for 30 minutes to prepare the gold-silver alloy with a hollow cubic structure.

[0024] Further preferably, 500 microliters of 100 mM ascorbic acid is added as a reducing agent to the mixed solution of the silver chloride-gold composite structure synthesized in S2, and the mixture is stirred evenly and allowed to stand for 30 minutes to obtain a hollow gold-silver alloy nanocube.

[0025] The present invention also provides a gold-silver alloy with a hollow cubic structure prepared by the method for preparing the gold-silver alloy with a hollow cubic structure. The size of the gold-silver alloy with a hollow cubic structure is adjustable. Under different molar ratios of silver nitrate and chloroauric acid, the size of the hollow gold-silver alloy nanocube can vary from 94 to 116 nm, and the surface plasmon resonance peak can vary from 600 to 740 nm, with a wide tunable range.

[0026] The present invention also includes the application of a gold-silver alloy with a hollow cubic structure. The gold-silver alloy with a hollow cubic structure has excellent catalytic activity and is quite rapid in model catalytic reactions, which is conducive to the application of the hollow gold-silver alloy nanocube in catalysts.

[0027] In summary, the present invention has the following beneficial effects: the preparation method of the present invention is simple, the size of the prepared hollow cubic structure gold-silver alloy can be adjusted, and under different molar ratios of silver nitrate and chloroauric acid, the size of the hollow gold-silver alloy nanocube can vary from 94 to 116 nm, and the surface plasmon resonance peak can vary from 600 to 740 nm, with a relatively wide tunable range. Moreover, the hollow cubic structure gold-silver alloy has a very rapid mode catalytic reaction, which is conducive to its application in catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of a method for preparing a gold-silver alloy with a hollow cubic structure provided by an embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of gold-silver alloys with hollow cubic structures of different sizes provided by an embodiment of the present invention;

[0030] Figure 3 Schematic diagram of element composition and selected area electron diffraction of a gold-silver alloy with a hollow cubic structure provided by an embodiment of the present invention;

[0031] Figure 4 It is the ultraviolet-visible spectrum diagram of the gold-silver alloy with hollow cubic structures of different sizes provided by the embodiment of the present invention;

[0032] Figure 5 is an XRD diffraction pattern of a gold-silver alloy with a hollow cubic structure provided by an embodiment of the present invention;

[0033] Figure 6 It is the overall preparation process roadmap provided by the embodiment of the present invention;

[0034] Figure 7 It is a diagram showing the catalytic effect of 20 μL and 50 μL hollow cube-structured gold-silver alloys provided in an embodiment of the present invention on 4-nitrophenol. DETAILED DESCRIPTION

[0035] The following is combined with Figure 1-7 The present invention is described in further detail.

[0036] Embodiment: A method for preparing a gold-silver alloy with a hollow cubic structure is based on a one-pot method and a step-by-step control method, using silver chloride as a template, sodium citrate with good biocompatibility and a single reducing agent, ascorbic acid, to prepare a gold-silver alloy with a hollow cubic structure.

[0037] The method for preparing a gold-silver alloy with a hollow cubic structure specifically comprises the following steps:

[0038] S1: Preparation of silver chloride microstructures;

[0039] S2: Preparation of silver chloride-gold composite structure;

[0040] S3: Preparation of gold-silver alloy with hollow cubic structure.

[0041] The specific operations are as follows:

[0042] Prepare a 20mM silver nitrate aqueous solution as a stock solution for later use; prepare a 1mM NaCl aqueous solution as a stock solution; at room temperature, take 100 microliters of the 20mM silver nitrate aqueous solution and dilute it to 4.2mL in a 20mL sample bottle, add 50 microliters of 2% sodium citrate, and then add 5mL of 1mM NaCl aqueous solution; shake well to see a slightly milky mixed solution, and a silver chloride microstructure is formed on the surface.

[0043] 100 mM ascorbic acid and 1% chloroauric acid (24.5 mM) were prepared for use; 1 mM ascorbic acid was obtained by diluting 100 mM ascorbic acid 100 times; 200 microliters of 1 mM ascorbic acid and chloroauric acid were added successively to the mixed solution in which the silver chloride microstructure was formed to form a silver chloride-gold composite structure with a preliminary cubic morphology.

[0044] A certain amount of ascorbic acid is added as a reducing agent to the synthesized mixed solution containing the silver chloride-gold composite structure, and the mixture is stirred evenly and allowed to stand for 30 minutes to obtain a gold-silver alloy with a hollow cubic structure.

[0045] A method for preparing a gold-silver alloy with a hollow cubic structure obtains a gold-silver alloy with a hollow cubic structure. The size of the gold-silver alloy with a hollow cubic structure synthesized by the method is adjustable. Under different molar ratios of silver nitrate and chloroauric acid, the size of the gold-silver alloy with a hollow cubic structure can vary from 94 to 116 nm, and the surface plasmon resonance peak can vary from 600 to 740 nm, with a wide tunable range.

[0046] The invention discloses an application of a gold-silver alloy with a hollow cubic structure. The hollow gold-silver alloy nanocube has excellent catalytic activity and is quite rapid in model catalytic reaction, which is beneficial to the application of the hollow gold-silver alloy nanocube in catalysts.

[0047] Experimental process:

[0048] Experimental Group 1:

[0049] Silver chloride microstructures were prepared at room temperature by diluting 100 μL of 20 mM diluted silver nitrate solution to 4.2 mL and then adding 5 mL of 1 mM sodium chloride solution;

[0050] In this group of experiments, no sodium citrate solution was added, and only the volume of the silver nitrate solution was changed (such as 20, 50, 150, or 200 microliters). The rest of the process was the same, and a mixed solution of silver chloride microstructures could also be prepared;

[0051] In the mixed solution of silver chloride microstructure, 1 mM ascorbic acid solution and 1% (24.5 mM) chloroauric acid solution were added successively to obtain a silver chloride-gold composite structure;

[0052] Finally, a large amount of (500 microliters of 100 mM) ascorbic acid solution was added to the mixed solution of the silver chloride-gold composite structure, and the mixture was shaken and allowed to stand for 30 minutes to obtain a gold-silver alloy with a hollow cubic structure.

[0053] The catalytic effect of the gold-silver alloy with a hollow cubic structure can be obtained in a model catalytic reaction of reducing 4-nitrophenol to 4-aminophenol.

[0054] Experimental Group 2:

[0055] At room temperature, 100 microliters of 20 mM diluted silver nitrate solution was diluted to 4.2 mL, 50 microliters of 2% sodium citrate solution was added, and then 5 mL of 1 mM sodium chloride solution was added to prepare silver chloride microstructures;

[0056] Only the volume of the silver nitrate solution is changed (such as 20, 50, 150, or 200 microliters), and the rest of the process is the same, and a mixed solution of silver chloride microstructure can also be prepared;

[0057] In the mixed solution of silver chloride microstructure, 1 mM ascorbic acid solution and 1% (24.5 mM) chloroauric acid solution were added successively to obtain a silver chloride-gold composite structure;

[0058] Finally, a large amount of (500 microliters of 100 mM) ascorbic acid solution was added to the mixed solution of the silver chloride-gold composite structure, and the mixture was shaken and allowed to stand for 30 minutes to obtain a gold-silver alloy with a hollow cubic structure.

[0059] Experimental Group 3:

[0060] Silver chloride microstructures were prepared at room temperature by diluting 100 μL of 20 mM diluted silver nitrate solution to 4.2 mL and then adding 5 mL of 1 mM sodium chloride solution;

[0061] In the mixed solution of silver chloride microstructure, only 1% (24.5 mM) chloroauric acid solution was added to obtain a silver chloride-gold composite structure;

[0062] Finally, a large amount of (500 microliters of 100 mM) ascorbic acid solution was added to the mixed solution of the silver chloride-gold composite structure, and the mixture was shaken and allowed to stand for 30 minutes to obtain a large number of spherical hollow gold-silver bimetallic structures.

[0063] Experimental Group 4:

[0064] Silver chloride microstructures were prepared at room temperature by diluting 100 μL of 20 mM diluted silver nitrate solution to 4.2 mL and then adding 5 mL of 1 mM sodium chloride solution;

[0065] In the mixed solution of silver chloride microstructure, (500 microliters of 100 mM) ascorbic acid solution is directly added, and after shaking, it is allowed to stand for 30 minutes to obtain a solid nano-silver particle structure.

[0066] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A method for preparing a gold-silver alloy with a hollow cubic structure, characterized in that: Based on the one-pot and step-by-step control methods, hollow cubic gold-silver alloys were prepared using silver chloride as a template, sodium citrate with good biocompatibility, and a single reducing agent, ascorbic acid. The specific steps include: S1: Preparation of silver chloride microstructure: At room temperature, a proper amount of sodium chloride is added to a certain amount of diluted silver nitrate solution to prepare a silver chloride microstructure; S2: preparing a silver chloride-gold composite structure: adding a small amount of sodium citrate, ascorbic acid and chloroauric acid to the mixed solution of silver nitrate and sodium chloride synthesized in step S1, to form a silver chloride-gold composite structure with a preliminary cubic morphology; S3: Preparation of a gold-silver alloy with a hollow cubic structure: Add a large amount of ascorbic acid as a reducing agent to the mixed solution of the silver chloride-gold composite structure synthesized in step S2, shake well and let stand for 30 minutes to prepare a gold-silver alloy with a hollow cubic structure.

2. The gold-silver alloy with a hollow cubic structure obtained by the method for preparing a gold-silver alloy with a hollow cubic structure according to claim 1 is characterized in that: The size of the gold-silver alloy with a hollow cubic structure is regulated to vary between 94 and 116 nm under different molar ratios of silver nitrate and chloroauric acid, and its surface plasma resonance peak varies between 600 and 740 nm.

3. An application of a gold-silver alloy with a hollow cubic structure, characterized by: Application of the gold-silver alloy with hollow cubic structure in catalyst.

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