Nanoscale silver-palladium triangular plate, preparation method thereof and application of nanoscale silver-palladium triangular plate in hydrogen production from formic acid

Abstract

The application discloses a nanoscale triangular sheet-shaped palladium-coated silver catalyst and a preparation method and application thereof. The method first prepares a seed suspension, uses the seed suspension to guide the generation of triangular silver nanosheets, and then coats a layer of nanometer palladium species on the triangular silver nanosheets. The method uses silver nitrate and palladium(II) nitrate dihydrate as reaction raw materials, so that the catalyst synthesis method is simple. The nanoscale triangular sheet-shaped palladium-coated silver catalyst prepared by the method has high hydrogen production efficiency and stability when used as a formic acid hydrogen production catalyst, the produced hydrogen is pollution-free and recyclable, can replace fossil fuels, and is an excellent energy substitute. Compared with noble metal single-atom catalysts and homogeneous catalysts, the nanoscale triangular sheet-shaped palladium-coated silver catalyst not only catalyzes the production of hydrogen from formic acid, but also greatly reduces the cost of the catalyst due to high hydrogen production efficiency and high raw material utilization rate, and the material is conducive to further scaled research on formic acid hydrogen production technology.

Description

Technical Field

[0001] This invention belongs to the field of new clean energy technology, specifically relating to a nanoscale silver-palladium triangular plate, its preparation method, and its application in hydrogen production from formic acid. Background Technology

[0002] The rapid depletion of fossil fuels and the environmental pollution caused by their combustion are prompting widespread exploration of renewable resources. To maintain sustainable development, the indispensability of fossil fuels must be overcome, and renewable energy must replace them. Comparative studies have found that hydrogen, with its high energy density, zero pollution, no CO2 emissions, and recyclability, is a promising clean energy carrier that can replace fossil fuels and has attracted widespread attention. Among the explored hydrogen production methods, the thermodynamically most supported method is the use of formic acid. Formic acid hydrogen production is considered a potential green and sustainable path for creating an energy-sustainable society because formic acid has high volumetric and gravimetric storage capacity for hydrogen, with a volumetric storage capacity reaching 53 g·L. -1 The mass storage capacity reaches 4.4%, and the energy density reaches 1.77 kWh·L. -1 Formic acid itself is non-toxic and is liquid at room temperature. Furthermore, formic acid is a renewable organic molecule that can be produced through CO2 hydrogenation and localized biological oxidation.

[0003] Although significant research has been conducted on noble metal-based single-atom catalysts for hydrogen production from formic acid, these noble metal materials are extremely scarce in the Earth's crust and are very expensive, which greatly limits their large-scale application in hydrogen production from formic acid. Furthermore, the local structure of single atoms in single-atom catalysts and the loading of metal single atoms are difficult to control. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a nanoscale silver-palladium triangular plate, its preparation method, and its application in formic acid hydrogen production, so as to solve the problems of high cost and difficult leaching of homogeneous catalysts for formic acid hydrogen production in the prior art.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for preparing a nanoscale silver-palladium triangular plate includes the following steps:

[0007] Step 1: Mix silver nitrate solution, trisodium citrate solution and sodium borohydride solution and stir. After stirring, store in the dark to obtain seed suspension.

[0008] Step 2: Stir the silver nitrate solution, polyvinylpyrrolidone solution, trisodium citrate solution and seed suspension evenly to obtain a mixed solution; add the mixed solution dropwise to the ascorbic acid solution while stirring continuously during the dropwise addition to obtain a triangular silver nanosheet solution;

[0009] Step 3: Add palladium dihydrate solution to triangular silver nanosheet solution, stir and obtain silver catalyst coated with nanoscale triangular palladium sheets.

[0010] A further improvement of the present invention is that:

[0011] Preferably, in step 1, the volume ratio of silver nitrate solution, trisodium citrate solution, and sodium borohydride solution is 2 mL: 0.685 L: 3 mL.

[0012] Preferably, in step 1, the molar concentration of silver nitrate solution is 0.1 mol / L, the molar concentration of trisodium citrate solution is 0.6 mol / L, and the molar concentration of sodium borohydride solution is 1 mol / L.

[0013] Preferably, in step 2, the volume ratio of silver nitrate solution, polyvinylpyrrolidone solution, trisodium citrate solution and seed suspension is 100:300:300:8.

[0014] Preferably, in step 2, the molar concentration of silver nitrate solution is 0.1 mol / L, the mass concentration of polyvinylpyrrolidone solution is 10 g / L, and the molar concentration of trisodium citrate solution is 0.6 mol / L.

[0015] Preferably, in step 2, the molar concentration of the ascorbic acid solution is 1.6 mol / L; the volume ratio of the ascorbic acid solution to the silver nitrate solution is 1:1.

[0016] Preferably, in step 3, the molar ratio of silver content in the triangular silver nanosheet solution to palladium content in the palladium dihydrate solution is 1:(2~0.01), wherein the concentration of the palladium dihydrate solution is 0.1 mol / L.

[0017] Preferably, after step 3, the nanoscale silver-palladium triangular plate catalyst is washed by centrifugation.

[0018] A nanoscale silver-palladium triangular plate prepared by the above preparation method includes triangular silver nanosheets, on which palladium is attached and can be detected.

[0019] An application of the above-mentioned nanoscale silver-palladium triangular plate in the hydrogen production of formic acid, wherein the nanoscale silver-palladium triangular plate serves as a catalyst.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention discloses a method for preparing nanoscale silver-palladium triangular plates. The method first prepares a seed suspension, which guides the formation of triangular silver nanosheets. These nanosheets are then reacted with a palladium solution to obtain a nanoscale silver-palladium triangular plate catalyst. The catalyst obtained by this method is a nanoscale two-dimensional material. Compared to single-atom noble metal catalysts, this nanoscale two-dimensional structure has a larger specific surface area. In the presence of an equal amount of noble metal, more of the noble metal, acting as active centers, is exposed on the material surface, significantly improving the utilization rate of the noble metal raw materials. This method uses silver nitrate and palladium(II) nitrate dihydrate as reactants, simplifying the catalyst synthesis process. The nanoscale triangular palladium-coated silver catalyst prepared by this method, when used as a formic acid hydrogen production catalyst, exhibits high and stable hydrogen production efficiency. The generated hydrogen is pollution-free, recyclable, and can replace fossil fuels, making it an excellent energy alternative. Compared to noble metal single-atom catalysts and homogeneous catalysts, this nanoscale silver-palladium triangular plate catalyst, with its nanoscale two-dimensional structure, boasts a larger specific surface area. Furthermore, because the palladium species are coated on the outside, palladium atoms exist only on the catalyst surface, avoiding waste due to their presence inside the material and non-participation in the reaction. Therefore, this method significantly improves palladium utilization and effectively reduces its input cost. Moreover, due to palladium's excellent hydrogen absorption and dehydrogenation properties, this method is more conducive to improving hydrogen production efficiency. This material is beneficial for further large-scale research into formic acid-to-hydrogen technology.

[0022] This invention also discloses a nanoscale silver-palladium triangular plate prepared by the above-described method. While existing noble metal single-atom catalysts do indeed have palladium species in single-atom form on their surface, more palladium exists within the catalyst, leading to raw material waste and increasing catalyst input costs to some extent; furthermore, homogeneous catalysts are difficult to separate from the reaction. The nanoscale triangular palladium-coated catalyst obtained by this invention is a nanoscale two-dimensional material, where palladium species exist only on the catalyst surface, avoiding the waste caused by palladium species remaining inside the catalyst and not participating in the reaction. Furthermore, the catalyst obtained by this invention is small in size and can be easily separated from the reaction by washing with water, providing an effective solution to the shortcomings of existing catalysts. Moreover, this method is simple to operate, and the prepared catalyst can effectively promote the development and utilization of hydrogen energy, opening up new avenues for the field of catalysts and offering a good solution to the energy crisis and environmental pollution.

[0023] This invention also discloses an application of a nanoscale silver-palladium triangular catalyst, which utilizes a nanoscale silver-palladium triangular catalyst to replace noble metal single-atom catalysts and homogeneous catalysts. This method provides a new opportunity to realize the industrial application of hydrogen production from formic acid. Experiments have confirmed that this catalyst has catalytic activity in the selective catalytic dehydrogenation of formic acid. The well-defined structure of the nanoscale silver-palladium triangular catalyst not only makes the local structure of the catalyst very clear and the atomic loading well-defined, but also, since palladium species are the active centers for formic acid dehydrogenation, they exist on the catalyst surface, which is the most efficient utilization of the active centers, far superior to noble metal single-atom catalysts and homogeneous catalysts. This application enables the efficient hydrogen production from formic acid, and thus makes hydrogen a clean energy carrier that can replace fossil fuels, an urgent priority.

[0024] Furthermore, the nanoscale silver-palladium triangular plate catalyst of the present invention can be used as a catalyst to catalytically decompose hydrogen-based formic acid at room temperature, and the generated H2 can serve as an effective solution to the energy crisis and environmental pollution.

[0025] The nanoscale silver-palladium triangular plate catalyst of this invention exhibits high selectivity and can efficiently catalyze the production of hydrogen from formic acid, while also solving the problems of difficult leaching and catalyst recovery from solution. Compared with noble metal single-atom catalysts and homogeneous catalysts, this nanoscale silver-palladium triangular plate catalyst not only significantly improves the catalytic efficiency of hydrogen-source formic acid but also reduces the cost of the catalyst. This material is beneficial for further large-scale research on formic acid hydrogen production technology. Attached Figure Description

[0026] Figure 1 Photographs of the dispersion morphology of the nanoscale silver-palladium triangular plate catalyst prepared in this invention;

[0027] Figure 2 TEM image of the nanoscale silver-palladium triangular plate catalyst prepared in Example 2 of this invention;

[0028] Figure 3 HAADF image of the nanoscale silver-palladium triangular plate catalyst prepared in Example 2 of this invention;

[0029] Figure 4 The elemental analysis diagram of the nanoscale silver-palladium triangular plate catalyst prepared in Example 2 of the present invention;

[0030] In this figure, (a) represents Ag; and (b) represents Pd.

[0031] Figure 5 The image shows data on the catalytic hydrogen production from formic acid using a nanoscale silver-palladium triangular plate catalyst prepared according to an embodiment of the present invention. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings:

[0033] Step 1: The first step is the synthesis of the seed suspension. 2 mL of silver nitrate solution, 0.685 L of trisodium citrate solution, and 3 mL of sodium borohydride solution are mixed thoroughly. The molar concentrations of the silver nitrate solution, trisodium citrate solution, and sodium borohydride solution are 0.1 mol / L, 0.6 mol / L, and 1 mol / L, respectively. After mixing thoroughly, the mixture is stirred at room temperature for ten minutes, then stopped and stored at room temperature in the dark for 6 hours to prevent the silver from oxidizing. This yields the seed suspension.

[0034] Step 2: Synthesize triangular silver nanosheets.

[0035] First, add 100 mL of silver nitrate solution, 300 mL of polyvinylpyrrolidone solution, 300 mL of trisodium citrate solution, and 8 mL of the seed suspension synthesized in step one to a beaker. The molar concentration of the silver nitrate solution is 0.1 mol / L, the mass concentration of the polyvinylpyrrolidone solution is 10 g / L, and the molar concentration of the trisodium citrate solution is 0.6 mol / L. Stir until the mixture is homogeneous.

[0036] The second step is to prepare an ascorbic acid solution with a molar concentration of 1.6 mol / L. Take 100 mL of the solution. At this point, the ascorbic acid solution acts as a reducing agent for the silver precursor. A stable precursor needs to be prepared in the first step above. Add the mixed solution obtained in the second step to the solution dropwise to avoid uneven contact between the silver precursor and ascorbic acid due to adding too quickly, which would result in the silver precursor not being completely reduced. Keep stirring during the process to obtain triangular silver nanosheets.

[0037] Step 3: Coating the surface of triangular silver nanosheets with palladium species. Prepare a 0.1 mol / L palladium(II) nitrate dihydrate solution. Take (0.01–200) mL of this solution, where the molar ratio of silver to palladium is 1:(2–0.01). Add this solution to the triangular silver nanosheet solution obtained in Step 3 and stir at room temperature for 2 h to obtain nanoscale silver-palladium triangular plates, i.e., Ag@Pd. (0.01-2) The side length of the triangle is 50nm.

[0038] Step 4, process the Ag@Pd synthesized in step 3. (0.01-2) Centrifugation was performed at 12,000 rpm for 10 minutes using deionized water as the washing solvent. The centrifuged product was dispersed in deionized water to maintain the stability of the catalyst.

[0039] The room temperature range involved in the above steps is 20 to 30°C.

[0040] This invention discloses a method for preparing a nanoscale silver-palladium triangular plate catalyst. The method involves forming silver nitrate into nanoscale triangular sheets, further growing palladium species on them, and then centrifuging and washing to obtain a silver catalyst material coated with palladium in nanoscale triangular sheets. This invention can reduce silver nitrate into regular triangular silver nanosheets at room temperature and grow palladium species at room temperature. This catalyst can efficiently catalyze the production of hydrogen from formic acid, addressing energy crises and environmental pollution problems. The technology is simple to operate and has high catalytic efficiency.

[0041] Example 1

[0042] Step 1: The first step is the synthesis of the seed suspension. 2 mL of silver nitrate solution, 0.685 L of trisodium citrate solution, and 3 mL of sodium borohydride solution are mixed thoroughly. The molar concentrations of the silver nitrate solution, trisodium citrate solution, and sodium borohydride solution are 0.1 mol / L, 0.6 mol / L, and 1 mol / L, respectively. After homogenization, the mixture is stirred at room temperature for ten minutes, then stopped and stored at room temperature in the dark for 6 hours. This yields the seed suspension.

[0043] Step 2: Synthesize triangular silver nanosheets.

[0044] First, add 100 mL of silver nitrate solution, 300 mL of polyvinylpyrrolidone solution, 300 mL of trisodium citrate solution, and 8 mL of the seed suspension synthesized in step one to a beaker. The molar concentration of the silver nitrate solution is 0.1 mol / L, the mass concentration of the polyvinylpyrrolidone solution is 10 g / L, and the molar concentration of the trisodium citrate solution is 0.6 mol / L. Stir until the mixture is homogeneous.

[0045] The second step is to prepare an ascorbic acid solution with a molar concentration of 1.6 mol / L. Take 100 mL of the solution and add the mixed solution obtained in step two dropwise, while keeping the mixture stirred, to obtain triangular silver nanosheets.

[0046] Step 3: Growing palladium species on the surface of triangular silver nanosheets. Prepare a 0.1 mol / L palladium(II) nitrate dihydrate solution. Take 100 mL of this solution, at which point the molar ratio of silver to palladium is 1:1. Add this solution to the triangular silver nanosheet solution obtained in Step 3 and stir at room temperature for 2 h to obtain a triangular silver nanosheet catalyst coated with palladium species, namely Ag@Pd.

[0047] Step 4: The Ag@Pd synthesized in Step 3 is centrifuged and washed. The centrifuge speed is 12000 rpm / min, the centrifugation time is 10 min, and the washing solvent is deionized water. The centrifuged product is dispersed in deionized water.

[0048] Example 2

[0049] Step 1: The first step is the synthesis of the seed suspension. 2 mL of silver nitrate solution, 0.685 L of trisodium citrate solution, and 3 mL of sodium borohydride solution are mixed thoroughly. The molar concentrations of the silver nitrate solution, trisodium citrate solution, and sodium borohydride solution are 0.1 mol / L, 0.6 mol / L, and 1 mol / L, respectively. After homogenization, the mixture is stirred at room temperature for ten minutes, then stopped and stored at room temperature in the dark for 6 hours. This yields the seed suspension.

[0050] Step 2: Synthesize triangular silver nanosheets.

[0051] First, add 100 mL of silver nitrate solution, 300 mL of polyvinylpyrrolidone solution, 300 mL of trisodium citrate solution, and 8 mL of the seed suspension synthesized in step one to a beaker. The molar concentration of the silver nitrate solution is 0.1 mol / L, the mass concentration of the polyvinylpyrrolidone solution is 10 g / L, and the molar concentration of the trisodium citrate solution is 0.6 mol / L. Stir until the mixture is homogeneous.

[0052] The second step is to prepare an ascorbic acid solution with a molar concentration of 1.6 mol / L. Take 100 mL of the solution and add the mixed solution obtained in step two dropwise, while keeping the mixture stirred, to obtain triangular silver nanosheets.

[0053] Step 3: Growing palladium species on the surface of triangular silver nanosheets. Prepare a 0.1 mol / L palladium(II) nitrate dihydrate solution. Take 80 mL of this solution, where the molar ratio of silver to palladium is 1:0.8. Add this solution to the triangular silver nanosheet solution obtained in Step 3 and stir at room temperature for 2 h to obtain a triangular silver nanosheet catalyst coated with palladium species, namely Ag@Pd. 0.8 .

[0054] Step 4, process the Ag@Pd synthesized in step 3. 0.8 Centrifugation washing was performed using a centrifuge at 12000 rpm / min for 10 min, with deionized water as the washing solvent. The centrifuged product was dispersed in deionized water.

[0055] Example 2 uses TEM, HAADF, and elemental analysis to study the reaction product prepared in this example, which is a nanoscale triangular palladium-coated silver catalyst (Ag@Pd). 0.8 Characterization was performed: photographs of its dispersed morphology are shown below. Figure 1 As shown, TEM and HAADF images are as follows: Figure 2 , 3 As shown, the product is confirmed to be triangular nanosheets, and the elemental analysis is as follows. Figure 4 As shown, the presence of silver and palladium elements is confirmed.

[0056] In Example 2, the key difference was that the volume of palladium solution used in the preparation of the nano-sized silver-palladium triangular plate catalyst was changed to 80 mL. The example demonstrated that when the volume of palladium solution was 80 mL, the catalyst produced hydrogen at the best efficiency, generating the largest volume of gas in the same time period.

[0057] Example 3

[0058] Step 1: The first step is the synthesis of the seed suspension. 2 mL of silver nitrate solution, 0.685 L of trisodium citrate solution, and 3 mL of sodium borohydride solution are mixed thoroughly. The molar concentrations of the silver nitrate solution, trisodium citrate solution, and sodium borohydride solution are 0.1 mol / L, 0.6 mol / L, and 1 mol / L, respectively. After homogenization, the mixture is stirred at room temperature for ten minutes, then stopped and stored at room temperature in the dark for 6 hours. This yields the seed suspension.

[0059] Step 2: Synthesize triangular silver nanosheets.

[0060] First, add 100 mL of silver nitrate solution, 300 mL of polyvinylpyrrolidone solution, 300 mL of trisodium citrate solution, and 8 mL of the seed suspension synthesized in step one to a beaker. The molar concentration of the silver nitrate solution is 0.1 mol / L, the mass concentration of the polyvinylpyrrolidone solution is 10 g / L, and the molar concentration of the trisodium citrate solution is 0.6 mol / L. Stir until the mixture is homogeneous.

[0061] The second step is to prepare an ascorbic acid solution with a molar concentration of 1.6 mol / L. Take 100 mL of the solution and add the mixed solution obtained in step two dropwise, while keeping the mixture stirred, to obtain triangular silver nanosheets.

[0062] Step 3: Coating palladium species onto the surface of triangular silver nanosheets. Prepare a 0.1 mol / L palladium(II) nitrate dihydrate solution. Take 60 mL of this solution, where the molar ratio of silver to palladium is 1:0.6. Add this solution to the triangular silver nanosheet solution obtained in Step 3 and stir at room temperature for 2 h to obtain a triangular silver nanosheet catalyst coated with palladium species, namely Ag@Pd. 0.6 .

[0063] Step 4, process the Ag@Pd synthesized in step 3. 0.6 Centrifugation washing was performed using a centrifuge at 12000 rpm / min for 10 min, with deionized water as the washing solvent. The centrifuged product was dispersed in deionized water.

[0064] In Example 3, the key difference was that the volume of palladium solution used in the preparation of the nano-sized silver-palladium triangular plate catalyst was changed to 60 mL. The example demonstrated that the catalyst produced hydrogen at a volume of 80 mL, resulting in the highest gas volume produced within the same time period.

[0065] Example 4

[0066] Step 1: The first step is the synthesis of the seed suspension. 2 mL of silver nitrate solution, 0.685 L of trisodium citrate solution, and 3 mL of sodium borohydride solution are mixed thoroughly. The molar concentrations of the silver nitrate solution, trisodium citrate solution, and sodium borohydride solution are 0.1 mol / L, 0.6 mol / L, and 1 mol / L, respectively. After homogenization, the mixture is stirred at room temperature for ten minutes, then stopped and stored at room temperature in the dark for 6 hours. This yields the seed suspension.

[0067] Step 2: Synthesize triangular silver nanosheets.

[0068] First, add 100 mL of silver nitrate solution, 300 mL of polyvinylpyrrolidone solution, 300 mL of trisodium citrate solution, and 8 mL of the seed suspension synthesized in step one to a beaker. The molar concentration of the silver nitrate solution is 0.1 mol / L, the mass concentration of the polyvinylpyrrolidone solution is 10 g / L, and the molar concentration of the trisodium citrate solution is 0.6 mol / L. Stir until the mixture is homogeneous.

[0069] The second step is to prepare an ascorbic acid solution with a molar concentration of 1.6 mol / L. Take 100 mL of the solution and add the mixed solution obtained in step two dropwise, while keeping the mixture stirred, to obtain triangular silver nanosheets.

[0070] Step 3: Growing palladium species on the surface of triangular silver nanosheets. Prepare a 0.1 mol / L palladium(II) nitrate dihydrate solution. Take 40 mL of this solution, where the molar ratio of silver to palladium is 1:0.4. Add this solution to the triangular silver nanosheet solution obtained in Step 3 and stir at room temperature for 2 h to obtain a triangular silver nanosheet catalyst coated with palladium species, namely Ag@Pd. 0.4 .

[0071] Step 4, process the Ag@Pd synthesized in step 3. 0.4 Centrifugation washing was performed using a centrifuge at 12000 rpm / min for 10 min, with deionized water as the washing solvent. The centrifuged product was dispersed in deionized water.

[0072] In Example 4, the key difference was that the volume of palladium solution used in the preparation of the nano-sized silver-palladium triangular plate catalyst was changed to 40 mL. The example demonstrated that the catalyst produced hydrogen at a volume of 80 mL, resulting in the highest gas volume produced within the same time period.

[0073] Example 4

[0074] Step 1: The first step is the synthesis of the seed suspension. 2 mL of silver nitrate solution, 0.685 L of trisodium citrate solution, and 3 mL of sodium borohydride solution are mixed thoroughly. The molar concentrations of the silver nitrate solution, trisodium citrate solution, and sodium borohydride solution are 0.1 mol / L, 0.6 mol / L, and 1 mol / L, respectively. After homogenization, the mixture is stirred at room temperature for ten minutes, then stopped and stored at room temperature in the dark for 6 hours. This yields the seed suspension.

[0075] Step 2: Synthesize triangular silver nanosheets.

[0076] First, add 100 mL of silver nitrate solution, 300 mL of polyvinylpyrrolidone solution, 300 mL of trisodium citrate solution, and 8 mL of the seed suspension synthesized in step one to a beaker. The molar concentration of the silver nitrate solution is 0.1 mol / L, the mass concentration of the polyvinylpyrrolidone solution is 10 g / L, and the molar concentration of the trisodium citrate solution is 0.6 mol / L. Stir until the mixture is homogeneous.

[0077] The second step is to prepare an ascorbic acid solution with a molar concentration of 1.6 mol / L. Take 100 mL of the solution and add the mixed solution obtained in step two dropwise, while keeping the mixture stirred, to obtain triangular silver nanosheets.

[0078] Step 3: Growing palladium species on the surface of triangular silver nanosheets. Prepare a 0.1 mol / L palladium(II) nitrate dihydrate solution. Take 20 mL of this solution, where the molar ratio of silver to palladium is 1:0.2. Add this solution to the triangular silver nanosheet solution obtained in Step 3 and stir at room temperature for 2 h to obtain a triangular silver nanosheet catalyst coated with palladium species, namely Ag@Pd. 0.2 .

[0079] Step 4 involves the Ag@Pd synthesized in Step 3. 0.2 Centrifugation washing was performed using a centrifuge at 12000 rpm / min for 10 min, with deionized water as the washing solvent. The centrifuged product was dispersed in deionized water.

[0080] In Example 5, the key difference was that the volume of palladium solution used in the preparation of the nano-sized silver-palladium triangular plate catalyst was changed to 20 mL. The example demonstrated that the catalyst produced hydrogen at a volume of 80 mL, resulting in the highest gas volume produced within the same time period.

[0081] Example 6

[0082] Step 1: The first step is the synthesis of the seed suspension. 2 mL of silver nitrate solution, 0.685 L of trisodium citrate solution, and 3 mL of sodium borohydride solution are mixed thoroughly. The molar concentrations of the silver nitrate solution, trisodium citrate solution, and sodium borohydride solution are 0.1 mol / L, 0.6 mol / L, and 1 mol / L, respectively. After homogenization, the mixture is stirred at room temperature for ten minutes, then stopped and stored at room temperature in the dark for 6 hours. This yields the seed suspension.

[0083] Step 2: Synthesize triangular silver nanosheets.

[0084] First, add 100 mL of silver nitrate solution, 300 mL of polyvinylpyrrolidone solution, 300 mL of trisodium citrate solution, and 8 mL of the seed suspension synthesized in step one to a beaker. The molar concentration of the silver nitrate solution is 0.1 mol / L, the mass concentration of the polyvinylpyrrolidone solution is 10 g / L, and the molar concentration of the trisodium citrate solution is 0.6 mol / L. Stir until the mixture is homogeneous.

[0085] The second step is to prepare an ascorbic acid solution with a molar concentration of 1.6 mol / L. Take 100 mL of the solution and add the mixed solution obtained in step two dropwise, while keeping the mixture stirred, to obtain triangular silver nanosheets.

[0086] Step 3: Growing palladium species on the surface of triangular silver nanosheets. Prepare a 0.1 mol / L palladium(II) nitrate dihydrate solution. Take 1 mL of this solution, where the molar ratio of silver to palladium is 1:0.01. Add this solution to the triangular silver nanosheet solution obtained in Step 3 and stir at room temperature for 2 h to obtain a triangular silver nanosheet catalyst coated with palladium species, namely Ag@Pd. 0.01 .

[0087] Step 4, process the Ag@Pd synthesized in step 3. 0.01 Centrifugation washing was performed using a centrifuge at 12000 rpm / min for 10 min, with deionized water as the washing solvent. The centrifuged product was dispersed in deionized water.

[0088] In Example 6, the key difference was that the volume of palladium solution used in the preparation of the nano-sized silver-palladium triangular plate catalyst was changed to 1 mL. The example demonstrated that the catalyst produced hydrogen at a volume of 80 mL, resulting in the highest gas volume produced within the same time period.

[0089] Example 7

[0090] Step 1: The first step is the synthesis of the seed suspension. 2 mL of silver nitrate solution, 0.685 L of trisodium citrate solution, and 3 mL of sodium borohydride solution are mixed thoroughly. The molar concentrations of the silver nitrate solution, trisodium citrate solution, and sodium borohydride solution are 0.1 mol / L, 0.6 mol / L, and 1 mol / L, respectively. After homogenization, the mixture is stirred at room temperature for ten minutes, then stopped and stored at room temperature in the dark for 6 hours. This yields the seed suspension.

[0091] Step 2: Synthesize triangular silver nanosheets.

[0092] First, add 100 mL of silver nitrate solution, 300 mL of polyvinylpyrrolidone solution, 300 mL of trisodium citrate solution, and 8 mL of the seed suspension synthesized in step one to a beaker. The molar concentration of the silver nitrate solution is 0.1 mol / L, the mass concentration of the polyvinylpyrrolidone solution is 10 g / L, and the molar concentration of the trisodium citrate solution is 0.6 mol / L. Stir until the mixture is homogeneous.

[0093] The second step is to prepare an ascorbic acid solution with a molar concentration of 1.6 mol / L. Take 100 mL of the solution and add the mixed solution obtained in step two dropwise, while keeping the mixture stirred, to obtain triangular silver nanosheets.

[0094] Step 3: Growing palladium species on the surface of triangular silver nanosheets. Prepare a 0.1 mol / L palladium(II) nitrate dihydrate solution. Take 200 mL of this solution, at which point the molar ratio of silver to palladium is 1:2. Add this solution to the triangular silver nanosheet solution obtained in Step 3 and stir at room temperature for 2 h to obtain a triangular silver nanosheet catalyst coated with palladium species, namely Ag@Pd2.

[0095] Step 4: The Ag@Pd2 synthesized in Step 3 is centrifuged and washed. The centrifuge speed is 12000 rpm / min, the centrifugation time is 10 min, and the washing solvent is deionized water. The centrifuged product is dispersed in deionized water.

[0096] In Example 7, the key difference was that the volume of palladium solution used in the preparation of the nano-sized silver-palladium triangular plate catalyst was changed to 200 mL. The example demonstrated that the catalyst produced hydrogen at a volume of 80 mL, resulting in the highest gas volume produced within the same time period.

[0097] See Figure 5 Performance tests were conducted on the products of specific implementation examples 1-7, and the volume of gas produced was statistically analyzed within the same time range. It can be seen that Ag@Pd 0.8 Formic acid has the strongest hydrogen production performance.

[0098] 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 within the protection scope of the present invention.

Claims

1. A method for preparing a nanoscale silver-palladium triangular plate, characterized in that, Includes the following steps: Step 1: Mix silver nitrate solution, trisodium citrate solution and sodium borohydride solution and stir. After stirring, store in the dark to obtain seed suspension. Step 2: Stir the silver nitrate solution, polyvinylpyrrolidone solution, trisodium citrate solution and seed suspension evenly to obtain a mixed solution; A mixed solution was added dropwise to an ascorbic acid solution with continuous stirring to obtain a triangular silver nanosheet solution. The volume ratio of silver nitrate solution, polyvinylpyrrolidone solution, trisodium citrate solution, and seed suspension was 100:300:300:

8. The molar concentration of silver nitrate solution was 0.1 mol / L, the mass concentration of polyvinylpyrrolidone solution was 10 g / L, the molar concentration of trisodium citrate solution was 0.6 mol / L, the molar concentration of ascorbic acid solution was 1.6 mol / L, and the volume ratio of ascorbic acid solution to silver nitrate solution was 1:

1. Step 3: Add palladium nitrate dihydrate solution to triangular silver nanosheet solution, stir and obtain nanoscale triangular palladium-coated silver catalyst; The molar ratio of silver content in the triangular silver nanosheet solution to palladium content in the palladium dihydrate solution is 1:(2~0.01), and the concentration of the palladium dihydrate solution is 0.1 mol / L.

2. The method for preparing a nanoscale silver-palladium triangular plate according to claim 1, characterized in that, In step 1, the volume ratio of silver nitrate solution, trisodium citrate solution, and sodium borohydride solution is 2 mL: 0.685 L: 3 mL.

3. The method for preparing a nanoscale silver-palladium triangular plate according to claim 1, characterized in that, In step 1, the molar concentration of silver nitrate solution is 0.1 mol / L, the molar concentration of trisodium citrate solution is 0.6 mol / L, and the molar concentration of sodium borohydride solution is 1 mol / L.

4. The method for preparing a nanoscale silver-palladium triangular plate according to claim 1, characterized in that, After step 3, the nanoscale silver-palladium triangular plate catalyst is washed by centrifugation.

5. A nanoscale silver-palladium triangular plate prepared by the preparation method according to any one of claims 1-4, characterized in that, It includes triangular silver nanosheets with palladium attached to them, and the palladium is detectable.

6. The application of the nanoscale silver-palladium triangular plate as described in claim 5 in the hydrogen production of formic acid, characterized in that, The nanoscale silver-palladium triangular plate serves as a catalyst.

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