Preparation method and application of gold-loaded bismuth-based nano material

Abstract

The invention discloses a preparation method of a gold-loaded bismuth-based nano material, which comprises the following steps: adding potassium bromide and bismuth nitrate pentahydrate into a mixed solution of deionized water and ethanol, heating and stirring; after the reaction is finished, filtering, collecting precipitates and drying to form bismuth oxybromide; the preparation method comprises the following steps: uniformly mixing tantalum pentoxide, bismuth oxybromide, bismuth oxide, sodium chloride and potassium chloride, putting the mixture into a crucible, putting the crucible into a muffle furnace, calcining, cleaning with deionized water, and finally drying to obtain the Bi4TaO8Br catalyst. The preparation method comprises the following steps: adding a Bi4TaO8Br catalyst into deionized water, stirring and dispersing uniformly, then adding a chloroauric acid solution and a methanol solution, illuminating by a xenon lamp, and stirring; after the reaction is finished, filtering, collecting a precipitate, and drying to form Au-Bi4TaO8Br. According to the bismuth-based piezoelectric catalyst Bi4TaO8Br prepared by the preparation method disclosed by the invention, metal gold is loaded on the surface of the bismuth-based piezoelectric catalyst Bi4TaO8Br, so that the good water oxidation performance of the catalyst is ensured, meanwhile, the loaded metal gold can provide sites required by an oxygen reduction reaction, and the purpose of efficiently preparing H2O2 by coupling water oxidation and the oxygen reduction reaction is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a preparation method and application of a gold-loaded bismuth-based nanomaterial. Background Art

[0002] Hydrogen peroxide (H2O2), a mild, economical, and green oxidant, has a wide range of applications in medicine and environmental remediation. The global demand for H2O2 is rapidly growing, leading to a widening gap between supply and demand. Unfortunately, the H2O2 production processes currently used in industry rely on anthraquinone technology and direct synthesis techniques, both of which are environmentally harmful, energy-intensive, and pose the risk of explosive hydrogen-oxygen mixtures. Furthermore, the concentration, storage, and transportation of H2O2 require significant manpower and material resources, posing potential safety risks. Therefore, the exploration of environmentally friendly, efficient, and convenient H2O2 synthesis technologies is urgent.

[0003] Piezoelectric catalysis applies mechanical stress to a piezoelectric material under ultrasonic drive, causing changes in its internal polarization and generating positive and negative charges. These positive and negative charges can then participate in redox reactions, producing H2O2 using water and oxygen as raw materials. This is a green and safe technology for producing H2O2. Piezoelectric catalysis requires a catalyst with significant polarization strength to provide a strong driving force for the reaction. Among the numerous piezoelectric catalysts, a class of Bi-based catalysts with a Sillén-Aurivillius structure (e.g., Bi4MO8X (M=Nb, Ta, X=Cl, Br)) not only possesses good polarization strength, but also shows great potential in producing H2O2 through water oxidation reaction. That is, during the piezoelectric catalytic process, the positive charge reacts with water to oxidize water into hydrogen peroxide. It is worth noting that the synthesis of H2O2 through piezoelectric catalysis can be carried out not only through water oxidation reaction, but also through oxygen reduction reaction. The oxygen reduction reaction refers to the reaction of negative charge with oxygen, reducing oxygen and combining it with hydrogen ions in water to produce hydrogen peroxide. Coupling the two modes of water oxidation and oxygen reduction is, in principle, believed to be able to increase the production of H2O2 by 2 times. However, the bismuth-based catalysts with the Sillén-Aurivillius structure show poor ability in the oxygen reduction reaction, which limits the efficient preparation of H2O2 by this type of piezoelectric catalyst.

[0004] Precious metals loaded on the catalyst surface can capture electrons generated during the catalytic reaction, which not only accelerates electron transfer and promotes the catalytic reaction, but also provides reaction sites for the catalytic reaction. Among the many precious metals, gold, when loaded on the catalyst surface as a reaction site, shows good selectivity for the oxygen reduction reaction to produce H2O2.

[0005] Therefore, it is necessary to propose a preparation method and application of gold-loaded bismuth-based nanomaterials to achieve the purpose of coupling water oxidation and oxygen reduction reactions to achieve efficient preparation of H2O2. Summary of the Invention

[0006] The present invention aims to solve the problem of how to achieve the coupling of water oxidation and oxygen reduction reaction to achieve the purpose of efficiently preparing H2O2, and proposes a preparation method and application of gold-loaded bismuth-based nanomaterials.

[0007] The method for preparing the gold-loaded bismuth-based nanomaterial comprises the following steps:

[0008] S1. Add potassium bromide and bismuth nitrate pentahydrate to a mixed solution of deionized water and ethanol, and heat and stir; after the reaction is completed, filter and collect the white precipitate, and dry it in an oven to form bismuth oxybromide powder;

[0009] S2. Tantalum pentoxide, bismuth oxybromide, bismuth oxide, sodium chloride, and potassium chloride were mixed evenly, placed in a crucible, and placed in a muffle furnace for calcination for 10 hours. After the reaction was completed, the sample was washed with deionized water to remove residual sodium chloride and potassium chloride, and finally dried in an oven to form a Bi4TaO8Br catalyst with a Sillén-Aurivillius structure.

[0010] S3. Add Bi4TaO8Br catalyst into deionized water and stir to disperse evenly, then add chloroauric acid solution and methanol solution, irradiate with xenon light and stir for 30 minutes; after the reaction is completed, filter and collect the precipitate, place in an oven at 60°C and dry to form gold-loaded Bi4TaO8Br catalyst Au-Bi4TaO8Br.

[0011] In a preferred embodiment of the present invention, S1 is specifically as follows: 2.38g of potassium bromide and 9.70g of bismuth nitrate pentahydrate are added to a mixed solution of 160ml of deionized water and 10ml of ethanol, heated and stirred at 70°C for 15h; after the reaction is completed, the white precipitate is collected by filtration and placed in an oven at 60°C for drying to form bismuth oxybromide powder.

[0012] Furthermore, S2 is specifically as follows: 0.88g of tantalum pentoxide, 1.22g of bismuth oxybromide, 2.80g of bismuth oxide, 2.34g of sodium chloride and 2.98g of potassium chloride are mixed evenly and placed in a crucible and placed in a muffle furnace. The heating program is set to 5°C / min and calcined at 700°C for 10h; after the reaction is completed, the sample is washed 5 times with deionized water to remove residual sodium chloride and potassium chloride, and finally placed in an oven at 60°C for drying to form a Sillén-Aurivillius structure Bi4TaO8Br catalyst.

[0013] Furthermore, S3 is specifically as follows: 25 mg of Bi4TaO8Br catalyst is added to 20 ml of deionized water and stirred to disperse evenly, followed by adding 250 ul of 1 mg / ml chloroauric acid solution, and then adding 2 ml of methanol solution, irradiating with a 300 W xenon lamp and stirring for 30 minutes; after the reaction is completed, the precipitate is collected by filtration and placed in an oven at 60°C for drying to form a gold-loaded Bi4TaO8Br catalyst Au-Bi4TaO8Br.

[0014] The Au-Bi4TaO8Br catalyst prepared by the above preparation method is used in the field of piezoelectric catalytic preparation of hydrogen peroxide.

[0015] The implementation of the embodiments of the present invention has the following beneficial effects:

[0016] The bismuth-based piezoelectric catalyst Bi4TaO8Br prepared by the preparation method of the gold-loaded bismuth-based nanomaterial of the present invention has metallic gold loaded on its surface. While ensuring the good water oxidation performance of the catalyst itself, the loaded gold metal can provide the sites required for the oxygen reduction reaction, thereby coupling the water oxidation and oxygen reduction reactions to achieve the purpose of efficiently preparing H2O2. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is the XRD pattern of Bi4TaO8Br material;

[0019] Figure 2 The left is the TEM image of the Au-Bi4TaO8Br catalyst, and the right is the EDS image of the gold element loaded on the surface of the Bi4TaO8Br catalyst;

[0020] Figure 3 This is the standard curve of hydrogen peroxide color developer;

[0021] Figure 4 Piezoelectric catalytic preparation of hydrogen peroxide using Bi4TaO8Br catalyst;

[0022] Figure 5 Piezoelectric catalytic preparation of hydrogen peroxide over Au-Bi4TaO8Br catalyst; DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0024] The preparation method of the gold-loaded bismuth-based nanomaterial comprises the following steps:

[0025] S1. Add 2.38 g of potassium bromide and 9.70 g of bismuth nitrate pentahydrate to a mixed solution of 160 ml of deionized water and 10 ml of ethanol, and heat with stirring at 70° C. for 15 h. After the reaction is completed, filter and collect the white precipitate, and dry it in an oven at 60° C. to form bismuth oxybromide powder.

[0026] S2. Mix 0.88g of tantalum pentoxide, 1.22g of bismuth oxybromide, 2.80g of bismuth oxide, 2.34g of sodium chloride and 2.98g of potassium chloride evenly, place them in a crucible and place it in a muffle furnace, set the heating program to 5°C / min, and calcine at 700°C for 10h; after the reaction is completed, use deionized water to wash the sample 5 times to remove residual sodium chloride and potassium chloride, and finally place it in an oven at 60°C to dry to form a Bi4TaO8Br catalyst with a Sillén-Aurivillius structure.

[0027] S3. Add 25 mg of Bi4TaO8Br catalyst to 20 ml of deionized water and stir to disperse evenly. Then add 250 μl of 1 mg / ml chloroauric acid solution and 2 ml of methanol solution. Irradiate with a 300 W xenon lamp and stir for 30 min. After the reaction is completed, filter and collect the precipitate, place it in an oven at 60°C and dry it to form the gold-loaded Bi4TaO8Br catalyst Au-Bi4TaO8Br.

[0028] This study prepared a bismuth-based piezoelectric catalyst, bismuth tantalate bromide (Bi4TaO8Br), with a Sillén-Aurivillius structure and loaded it with gold. While maintaining the catalyst's inherently good water oxidation performance, the loaded gold provides sites for the oxygen reduction reaction, coupling the water oxidation and oxygen reduction reactions to achieve efficient H2O2 production.

[0029] Performance Study:

[0030] The Bi4TaO8Br catalyst prepared in S2 was tested by XRD, see Figure 1 , Figure 1 This is the XRD pattern of Bi4TaO8Br material.

[0031] The Au-Bi4TaO8Br catalyst prepared in S3 was characterized by TEM and EDS, see Figure 2 , Figure 2 The left is the TEM photo of the Au-Bi4TaO8Br catalyst, and the right is the EDS image of the gold element loaded on the surface of the Bi4TaO8Br catalyst. Figure 2 The transmission electron microscopy results show that gold metal is loaded on the Bi4TaO8Br catalyst, and EDS detects obvious gold element distribution on the surface of the catalyst.

[0032] Prepare a hydrogen peroxide colorimetric standard curve to calibrate the concentration of hydrogen peroxide produced during the reaction. The specific preparation process is as follows:

[0033] 1. Prepare 0.4 mol / L potassium iodide and 0.1 mol / L potassium hydrogen phthalate solutions respectively.

[0034] 2. Take 1 ml of hydrogen peroxide of known concentration and add 0.5 ml of prepared potassium iodide and potassium hydrogen phthalate solution respectively. Mix well and let it stand for more than 2 hours. After it develops color, use UV-visible absorption spectroscopy to test its absorption peak intensity at 350 nm.

[0035] 3. Convert the concentration of hydrogen peroxide according to the absorption peak intensity. The standard curve results are as follows: Figure 3 shown.

[0036] 4. In subsequent tests, take 1 ml of the sample to be tested and add 0.5 ml of the prepared potassium iodide and potassium hydrogen phthalate solutions respectively. Calculate the hydrogen peroxide concentration of the sample to be tested based on the standard curve.

[0037] The piezoelectric catalytic preparation of hydrogen peroxide by Bi4TaO8Br catalyst is as follows:

[0038] Disperse the Bi4TaO8Br catalyst evenly in 30ml of aqueous solution, replace the reaction with oxygen or argon, seal the reaction vessel, and then place the reactor in an ultrasonic machine to start the reaction. The amount of catalyst is 0.025g; the ultrasonic machine power is 120W; the frequency is 80kHz; and circulating cooling water is added throughout the reaction process to ensure the reaction temperature is around 25°C. The method for testing the hydrogen peroxide concentration of the sample is consistent with the above method. A control group without adding catalyst is set up, and the experimental results are as follows Figure 4 .

[0039] Figure 4The results show that the Bi4TaO8Br catalyst exhibits optimal performance in an argon atmosphere, producing 0.51 μmol / ml of hydrogen peroxide in 2 hours. In an argon atmosphere, the only raw material involved in the piezoelectric catalytic reaction is water, which is consistent with the excellent water oxidation performance of this type of catalyst. In an oxygen atmosphere, the piezoelectric catalytic reaction involves not only water but also oxygen. However, due to the Bi4TaO8Br catalyst's weak oxygen reduction performance, not only is oxygen not consumed in the reaction, but it also affects the catalyst's original water oxidation performance.

[0040] Au-Bi4TaO8Br catalyst piezoelectrically prepares hydrogen peroxide. The specific process is as follows:

[0041] The Au-Bi4TaO8Br catalyst was evenly dispersed in 30ml of aqueous solution. The experimental preparation process and test method were the same as above. Figure 5 shown.

[0042] Please refer to Table 1, which shows the piezoelectric catalytic hydrogen peroxide production of different catalysts in different atmospheres. The results in Table 1 show that the hydrogen peroxide production of the Au-Bi4TaO8Br catalyst in an oxygen atmosphere is 2.53umol / ml in 2 hours, which is approximately 2.07 times the hydrogen peroxide production of 1.22umol / ml in an argon atmosphere. By loading gold on the catalyst surface, the original disadvantage of the Bi4TaO8Br catalyst's poor oxygen reduction performance has been overcome. While providing the reaction sites required for the oxygen reduction reaction, the gold loading also improves the catalyst's overall performance in producing hydrogen peroxide. The hydrogen peroxide production of the Au-Bi4TaO8Br catalyst in an argon atmosphere in 2 hours is approximately 2.39 times that of the Bi4TaO8Br catalyst.

[0043] Table 1 Piezoelectric catalytic hydrogen peroxide production of different catalysts in different atmospheres

[0044] catalyst atmosphere Hydrogen peroxide concentration after 2h reaction (umol / ml) / oxygen 0.06 / Argon 0.05 <![CDATA[Bi4TaO8Br]]> oxygen 0.28 <![CDATA[Bi4TaO8Br]]> Argon 0.51 <![CDATA[Au-Bi4TaO8Br]]> oxygen 2.53 <![CDATA[Au-Bi4TaO8Br]]> Argon 1.22

[0045] According to the experimental results, the Au-Bi4TaO8Br catalyst prepared by the preparation method of the present invention can be applied to the field of piezoelectric catalytic preparation of hydrogen peroxide with excellent effect.

[0046] The present invention prepares a bismuth-based piezoelectric catalyst Bi4TaO8Br with good water oxidation performance for preparing hydrogen peroxide.

[0047] The water oxidation reaction, used to produce hydrogen peroxide, is a potentially valuable half-reaction that couples numerous reduction reactions, such as carbon dioxide reduction, nitrogen fixation, and hydrogen evolution reactions. However, producing hydrogen peroxide solely through the water oxidation half-reaction suffers from low charge utilization, resulting in a 50% loss in hydrogen peroxide yield, preventing maximum hydrogen peroxide production. By loading gold onto Bi4TaO8Br, the poor oxygen reduction performance of this bismuth-based catalyst is addressed. This provides oxygen reduction sites for the reaction, enabling the coupling of water oxidation and oxygen reduction reactions to double hydrogen peroxide production.

[0048] By loading gold on Bi4TaO8Br, it not only provides oxygen reduction reaction sites for the reaction, but also promotes rapid charge separation, further improving the water oxidation performance of the Bi4TaO8Br catalyst itself by 2.39 times, killing two birds with one stone.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a gold-loaded bismuth-based nanomaterial, characterized in that: The following steps are involved: S1. Add potassium bromide and bismuth nitrate pentahydrate to a mixed solution of deionized water and ethanol, and heat and stir; after the reaction is completed, filter and collect the white precipitate, and dry it in an oven to form bismuth oxybromide powder; S2. Tantalum pentoxide, bismuth oxybromide, bismuth oxide, sodium chloride, and potassium chloride were mixed evenly, placed in a crucible, and placed in a muffle furnace for calcination for 10 hours. After the reaction was completed, the sample was washed with deionized water to remove residual sodium chloride and potassium chloride, and finally dried in an oven to form a Bi4TaO8Br catalyst with a Sillén-Aurivillius structure. S3. Add Bi4TaO8Br catalyst into deionized water and stir to disperse evenly, then add chloroauric acid solution and methanol solution, irradiate with xenon light and stir for 30 minutes; after the reaction is completed, filter and collect the precipitate, place in an oven at 60°C and dry to form gold-loaded Bi4TaO8Br catalyst Au-Bi4TaO8Br.

2. The method for preparing the gold-loaded bismuth-based nanomaterial according to claim 1, wherein Specifically, S1 comprises the following steps: adding 2.38 g of potassium bromide and 9.70 g of bismuth nitrate pentahydrate to a mixed solution of 160 ml of deionized water and 10 ml of ethanol, heating and stirring at 70° C. for 15 h; after the reaction is completed, filtering and collecting the white precipitate, and drying it in an oven at 60° C. to form bismuth oxybromide powder.

3. The method for preparing the gold-loaded bismuth-based nanomaterial according to claim 2, wherein: Specifically, S2 is as follows: 0.88g of tantalum pentoxide, 1.22g of bismuth oxybromide, 2.80g of bismuth oxide, 2.34g of sodium chloride and 2.98g of potassium chloride are mixed evenly and placed in a crucible and placed in a muffle furnace. The heating program is set to 5°C / min and calcined at 700°C for 10h; after the reaction is completed, the sample is washed 5 times with deionized water to remove residual sodium chloride and potassium chloride, and finally placed in an oven at 60°C for drying to form a Bi4TaO8Br catalyst with a Sillén-Aurivillius structure.

4. The method for preparing the gold-loaded bismuth-based nanomaterial according to claim 3, wherein: Specifically, S3 comprises the following steps: adding 25 mg of Bi4TaO8Br catalyst to 20 ml of deionized water and stirring to disperse evenly, then adding 250 ul of 1 mg / ml chloroauric acid solution, and then adding 2 ml of methanol solution, irradiating with a 300 W xenon lamp and stirring for 30 minutes; after the reaction is completed, filtering and collecting the precipitate, and drying it in an oven at 60° C. to form a gold-loaded Bi4TaO8Br catalyst, Au-Bi4TaO8Br.

5. The method for preparing the gold-loaded bismuth-based nanomaterial according to any one of claims 1 to 4, characterized in that: The Au-Bi4TaO8Br catalyst prepared by the preparation method is applied in the field of piezoelectric catalytic preparation of hydrogen peroxide.

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