Palladium-platinum alloy mesoporous nanowire and preparation method and application thereof

Abstract

The invention provides a palladium-platinum alloy mesoporous nanowire as well as a preparation method and application thereof, and belongs to the technical field of nano materials. The palladium-platinum alloy mesoporous nanowire provided by the invention has palladium and platinum, so that after the two metal elements form an alloy, a synergistic effect can be generated, and the conductivity and the electro-catalytic property are improved; the mesoporous structure can increase the active surface area and further improve the electro-catalytic performance; the diameter of the palladium-platinum alloy mesoporous nanowire provided by the invention is nanoscale, and a plurality of mesopores are distributed in the center, so that the number of active sites can be increased; therefore, when the material is used as a modification material of an electrode in an electrochemical sensor, the material has excellent electrocatalytic activity and conductivity. The result of the embodiment shows that the electrochemical active area (ECSA) of the palladium-platinum alloy mesoporous nanowire modified electrode material provided by the invention is 0.232 cm < 2 >, and the electrode material has relatively high electrocatalytic activity.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a palladium-platinum alloy mesoporous nanowire and a preparation method and application thereof. Background Art

[0002] Using pesticides to reduce crop diseases and insect pests is a major method in the field of agricultural production. However, during use, pesticides will be retained in crops and the ecological environment through spraying, and enter the human body through the ecological cycle, causing irreversible harm to the human body. Therefore, with the increasing attention paid to environmental and food safety, countries around the world have formulated a series of standards to strictly control pesticide residues in food. At the same time, it is becoming increasingly important to choose a convenient, efficient, sensitive and accurate method for detecting pesticide residues. The electrochemical AChE biosensor has the advantages of accurate and rapid detection, simple operation, low cost and convenience for on-site detection, and has great application potential in pesticide residue detection.

[0003] In the preparation process of electrochemical biosensors, the selection of electrode modification materials is crucial to the performance of the sensor. In recent years, researchers have prepared various nanomaterials with different morphologies for the construction of new biosensors in the hope of improving the detection performance of the sensor. Among the many nanomaterials, one-dimensional nanomaterials, including nanofibers, nanowires, nanorods, nanobelts and nanotubes, can effectively promote electron transfer and improve chemical reaction activity. However, palladium-platinum alloys are currently often present in the form of nanoparticles. For example, the relevant prior art discloses a method for preparing platinum / palladium alloy nanoparticle catalysts, which can obtain nanoparticle catalysts with adjustable size and composition, but there are no reports on palladium-platinum alloy mesoporous nanowires. Summary of the invention

[0004] The object of the present invention is to provide a palladium-platinum alloy mesoporous nanowire and a preparation method and application thereof. The palladium-platinum alloy mesoporous nanowire provided by the present invention has high electrocatalytic activity when used as an electrode modification material for an electrochemical biosensor.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a palladium-platinum alloy mesoporous nanowire, wherein the average diameter of the palladium-platinum alloy mesoporous nanowire is 12 to 18 nm; the mesopores of the palladium-platinum alloy mesoporous nanowire are distributed in the center;

[0007] The palladium and platinum in the palladium-platinum alloy mesoporous nanowires are in an alloy phase; the palladium exists in a Pd 3d state, and the platinum exists in a Pt4f state; the amount ratio of the palladium to the platinum is (1-3):(1-6).

[0008] The present invention also provides a method for preparing the palladium-platinum alloy mesoporous nanowires described in the above technical solution, comprising the following steps:

[0009] (1) mixing a reducing agent, a surfactant, a structure directing agent, palladium nanowires, and a solvent to obtain a precursor mixture;

[0010] (2) After preheating the precursor mixed solution obtained in step (1), the platinum source solution is added dropwise to the preheated precursor solution to perform a reduction reaction to obtain palladium-platinum alloy mesoporous nanowires.

[0011] Preferably, the reducing agent in step (1) comprises ascorbic acid or glucose.

[0012] Preferably, the surfactant in step (1) comprises polyvinyl pyrrolidone or hexadecyltrimethylammonium bromide.

[0013] Preferably, the structure directing agent in step (1) is sodium iodide, polyvinyl pyrrolidone, polyvinyl alcohol or polyethylene glycol.

[0014] Preferably, in step (1), the average diameter of the palladium nanowires is 6 to 12 nm.

[0015] Preferably, the mass ratio of the reducing agent, surfactant, structure directing agent and palladium nanowires in step (1) is (0.020-0.030):(0.25-0.65):(0.10-0.20):(0.00050-0.0015).

[0016] Preferably, the rate of dropping the platinum source solution in step (2) is 0.5 to 2 mL / h.

[0017] Preferably, the temperature of the reduction reaction in step (2) is 110-210° C., and the time of the reduction reaction is 0.5-1.5 h.

[0018] The present invention also provides the use of the palladium-platinum alloy mesoporous nanowires described in the above technical solution or the palladium-platinum alloy mesoporous nanowires prepared by the preparation method described in the above technical solution as a modification material for electrodes in electrochemical sensors.

[0019] The present invention provides a palladium-platinum alloy mesoporous nanowire, wherein the average diameter of the palladium-platinum alloy mesoporous nanowire is 12 to 18 nm; the mesopores are distributed in the center of the palladium-platinum alloy mesoporous nanowire; the palladium and platinum in the palladium-platinum alloy mesoporous nanowire are alloy phases; the palladium exists in the state of Pd 3d, and the platinum exists in the state of Pt 4f; the amount ratio of the palladium to the platinum is (1 to 3): (1 to 6). The palladium-platinum alloy mesoporous nanowire provided by the present invention has palladium and platinum. After the two metal elements form an alloy in the range of (1 to 3): (1 to 6), a synergistic effect can be produced to improve the conductivity and electrocatalytic performance; its mesoporous structure can increase the active surface area and improve the electrocatalytic performance; the palladium-platinum alloy mesoporous nanowire provided by the present invention has a diameter of nanometer scale, and a plurality of mesopores are distributed in the center, which can increase the number of active sites; therefore, when it is used as a modified material for the electrode in the electrochemical sensor, it has excellent catalytic performance. The results of the embodiment show that the electrochemically active area (ECSA) of the electrode material modified by the palladium-platinum alloy mesoporous nanowire provided by the present invention is 0.232 cm 2 , with high electrocatalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 TEM image of palladium-platinum alloy mesoporous nanowires provided in Example 1 of the present invention;

[0021] Figure 2 TEM image of palladium-platinum alloy mesoporous nanowires provided in Example 2 of the present invention;

[0022] Figure 3 TEM image of palladium-platinum alloy mesoporous nanowires provided in Example 3 of the present invention;

[0023] Figure 4 CV curve diagram of the electrode prepared in Application Example 1 of the present invention;

[0024] Figure 5 It is a linear fitting diagram of the CV curve diagram of the electrode prepared in Application Example 1 of the present invention;

[0025] Figure 6 CV curve diagram of the electrode prepared in Application Example 2 of the present invention;

[0026] Figure 7 The linear fitting diagram of the CV curve of the electrode prepared in Application Example 2 of the present invention;

[0027] Figure 8 CV curve diagram of the electrode prepared in Application Example 3 of the present invention;

[0028] Fig. 9 It is a linear fitting diagram of the CV curve of the electrode prepared in Application Example 3 of the present invention;

[0029] Fig.10 The XRD pattern of palladium-platinum alloy mesoporous nanowires provided in Example 3 of the present invention;

[0030] Fig.11 This is an EDS image of the palladium-platinum alloy mesoporous nanowires provided in Example 3 of the present invention;

[0031] Fig.12 This is the XPS image of the palladium-platinum alloy mesoporous nanowires provided in Example 3 of the present invention;

[0032] Fig.13 CV curves of electrodes modified with different materials of the present invention;

[0033] Fig.14 EIS curve diagram of CV curves of electrodes modified with different materials of the present invention;

[0034] Fig.15 The graphs are current response curves of different enzyme electrodes of the present invention to 4 mmol / L substrate ATCh. DETAILED DESCRIPTION

[0035] The present invention provides a palladium-platinum alloy mesoporous nanowire, wherein the average diameter of the palladium-platinum alloy mesoporous nanowire is 12 to 18 nm; the mesopores of the palladium-platinum alloy mesoporous nanowire are distributed in the center;

[0036] The palladium and platinum in the palladium-platinum alloy mesoporous nanowires are in an alloy phase; the palladium exists in a Pd 3d state, and the platinum exists in a Pt4f state; the amount ratio of the palladium to the platinum is (1-3):(1-6).

[0037] In the present invention, the average diameter of the palladium-platinum alloy mesoporous nanowires is 12 to 18 nm, preferably 12 to 15 nm. The diameter of the palladium-platinum alloy mesoporous nanowires provided by the present invention is within the above range and has a nanoscale size, which enables the palladium-platinum alloy mesoporous nanowires to have a larger specific surface area; the mesoporous structure is conducive to the exposure of active sites, so that the palladium-platinum alloy mesoporous nanowires have better electrocatalytic activity.

[0038] In the present invention, the mesopores are distributed in the center of the palladium-platinum alloy mesoporous nanowire. In the present invention, the pore size of the mesopores is preferably 2.3 to 5.6 nm. The mesopores in the palladium-platinum alloy mesoporous nanowires provided by the present invention can increase the contact sites, thereby making the palladium-platinum alloy mesoporous nanowires have higher electrocatalytic activity when used as electrode modification materials for electrochemical biosensors. The present invention does not specifically limit the number of the mesopores, and it can be adjusted as needed.

[0039] In the present invention, the palladium and platinum in the palladium-platinum alloy mesoporous nanowires are in an alloy phase.

[0040] In the present invention, the palladium exists in the state of Pd 3d, and the state of Pd 3d preferably includes Pd3d5 / 2 and Pd3d3 / 2; the platinum exists in the state of Pt 4f, and the state of Pt 4f preferably includes Pt 4f7 / 2 and Pt 4f5 / 2. When the palladium and platinum in the palladium-platinum alloy mesoporous nanowires provided by the present invention exist in the above states, they can play a synergistic role and improve the conductivity; the presence of mesopores is conducive to increasing the active sites, thereby improving the detection performance of the sensor modified with the palladium-platinum alloy mesoporous nanowires.

[0041] In the present invention, the molar ratio of palladium to platinum is preferably (1 to 3): (1 to 6), and more preferably 1: 2 to 5. In the palladium-platinum alloy mesoporous nanowires provided by the present invention, palladium and platinum form an alloy phase in the above-mentioned molar ratio, and the addition of platinum can improve the conductivity of the palladium-platinum alloy mesoporous nanowires.

[0042] The present invention also provides a method for preparing the palladium-platinum alloy mesoporous nanowires described in the above technical solution, comprising the following steps:

[0043] (1) mixing a reducing agent, a surfactant, a structure directing agent, palladium nanowires, and a solvent to obtain a precursor mixture;

[0044] (2) After preheating the precursor mixed solution obtained in step (1), the platinum source solution is added dropwise to the preheated precursor solution to perform a reduction reaction to obtain palladium-platinum alloy mesoporous nanowires.

[0045] In the present invention, the reducing agent preferably includes ascorbic acid or glucose, and more preferably ascorbic acid. The present invention uses a reducing agent to reduce the platinum source to platinum.

[0046] In the present invention, the surfactant preferably includes polyvinyl pyrrolidone or hexadecyl trimethyl ammonium bromide, and more preferably polyvinyl pyrrolidone. The present invention utilizes the surfactant to promote the uniform dispersion of palladium nanowires in the precursor mixture.

[0047] In the present invention, the structure directing agent preferably includes sodium iodide, polyvinyl pyrrolidone, polyvinyl alcohol or polyethylene glycol. The present invention utilizes the structure directing agent to guide the platinum source to form an alloy with the palladium nanowire during the reduction reaction.

[0048] In the present invention, the average diameter of the palladium nanowires is preferably 6 to 12 nm, more preferably 6 to 10 nm.

[0049] The present invention has no special limitation on the source of the palladium nanowires, and conventional methods or commercially available products may be used.

[0050] In the present invention, the method for preparing the palladium nanowires is preferably: dissolving a palladium salt, a surfactant and a structure directing agent in water to obtain a palladium-containing solution; and subjecting the palladium-containing solution to a hydrothermal reaction to obtain palladium nanowires.

[0051] In the present invention, the palladium salt, the surfactant and the structure directing agent are preferably dissolved in water to obtain a palladium-containing solution.

[0052] In the present invention, the palladium salt is preferably one or more of palladium chloride, palladium acetate and palladium nitrate.

[0053] In the present invention, the surfactant is preferably polyvinyl pyrrolidone and / or cetyltrimethylammonium bromide.

[0054] In the present invention, the structure directing agent is preferably sodium iodide, polyvinyl pyrrolidone, polyvinyl alcohol or polyethylene glycol.

[0055] In the present invention, the mass ratio of the palladium salt, the surfactant and the structure directing agent is preferably (0.01-0.02):(0.5-1.5):(0.2-0.4), and more preferably 0.0177:1:0.3.

[0056] The present invention has no particular limitation on the amount of water used, and it can be adjusted as needed.

[0057] After obtaining the palladium-containing solution, the present invention preferably subjects the palladium-containing solution to a hydrothermal reaction to obtain palladium nanowires.

[0058] In the present invention, the temperature of the hydrothermal reaction is preferably 200-240°C, more preferably 220°C; the time of the hydrothermal reaction is preferably 2-4h, more preferably 3h. The present invention causes the palladium salt to undergo a reduction reaction through the hydrothermal reaction, and forms palladium nanowires under the action of a surfactant and a structure directing agent.

[0059] In the present invention, after the hydrothermal reaction, the system obtained by the hydrothermal reaction is preferably washed and dried in sequence to obtain palladium nanowires. The present invention has no particular limitation on the washing and drying methods, and conventional washing and drying methods can be used to fully remove impurities in the palladium nanowires.

[0060] In the present invention, the mass ratio of the reducing agent, surfactant, structure directing agent and palladium nanowires is preferably (0.020-0.030): (0.25-0.65): (0.10-0.20): (0.00050-0.0015), and more preferably (0.025-0.030): (0.35-0.65): (0.15-0.20): (0.0010-0.0015).

[0061] In the present invention, the solvent preferably includes hexylene glycol, hydrazine hydrate or oleylamine. The present invention uses a solvent to dissolve the reducing agent, the surfactant and the structure directing agent.

[0062] The present invention has no special limitation on the amount of the solvent, which can be adjusted according to the amounts of the reducing agent, the surfactant and the structure directing agent so as to completely dissolve the above components.

[0063] The present invention has no particular limitation on the method for mixing the reducing agent, surfactant, structure directing agent, palladium nanowires and solvent, as long as the reducing agent, surfactant and structure directing agent can be completely dissolved.

[0064] After obtaining the precursor mixed solution, the present invention preheats the precursor mixed solution, and then drops a platinum source solution into the preheated precursor solution to perform a reduction reaction to obtain palladium-platinum alloy mesoporous nanowires.

[0065] In the present invention, the preheating temperature is preferably 100-120°C, more preferably 110°C. The present invention does not specifically limit the preheating time, and the temperature of the precursor solution can be preheated to the above temperature range. In an embodiment of the present invention, the preheating time can be 20 minutes. The present invention preheats the precursor solution first, so that the platinum source solution reacts when it is added dropwise to the precursor solution, so that the composition of the alloy in the obtained product is more uniform.

[0066] In the present invention, the solvent of the platinum source solution is preferably hexylene glycol, and the platinum source in the platinum source solution is preferably chloroplatinic acid or platinum chloride, more preferably chloroplatinic acid.

[0067] In the present invention, the concentration and volume of the platinum source solution are preferably adjusted according to the concentration of palladium nanowires in the precursor mixture, so that the molar ratio of the palladium nanowires in the precursor mixture and the platinum source in the platinum source solution can reach the desired level. In the present invention, the molar ratio of the palladium nanowires and the platinum source in the precursor mixture is preferably (7.6-13.2): (20-80), and more preferably (9.4-13.2): (40-80). In an embodiment of the present invention, the concentration of the palladium nanowires in the platinum precursor mixture may be 0.38 mmol / L, 0.66 mmol / L or 0.47 mmol / L, and the volume of the palladium nanowires in the platinum precursor mixture may be 20 mL; the concentration of the platinum source solution may be 4 mmol / L, 8 mmol / L or 16 mmol / L, and the volume of the platinum source solution may be 5 mL. The present invention controls the amount of platinum source and palladium nanowires within the above range, which is more conducive to making the amount ratio of palladium and platinum in the palladium-platinum alloy mesoporous nanowires reach the desired range.

[0068] In the present invention, the platinum source solution is added at a rate of preferably 0.5 to 2 mL / h, more preferably 1.5 mL / h. By controlling the platinum source solution addition rate within the above range, the present invention can prevent uneven distribution of platinum in the formed alloy caused by excessively fast addition of the platinum source solution.

[0069] In the present invention, the temperature of the reduction reaction is preferably 110-210°C, more preferably 190-210°C; the time of the reduction reaction is preferably 0.5-1.5h, more preferably 1-1.5h. Under the above temperature and time, the present invention can reduce the platinum source to platinum under the action of the reducing agent, and form an alloy with palladium at high temperature; at the same time, palladium-platinum alloy mesoporous nanowires are formed under the guidance of the surfactant and sodium iodide.

[0070] In the present invention, the product after the reduction reaction is preferably post-treated to obtain palladium-platinum alloy mesoporous nanowires.

[0071] In the present invention, the post-treatment is preferably solid-liquid separation, washing and drying performed sequentially.

[0072] In the present invention, the solid-liquid separation method is preferably centrifugal; the centrifugal speed is preferably 4000-6000 r / min, more preferably 5000-6000 r / min; the centrifugal time is preferably 12-18 min, more preferably 15 min. The present invention can separate the solid and liquid in the oil bath thermal reaction liquid by solid-liquid separation.

[0073] In the present invention, the washing method is preferably to wash with an organic solution first and then with water. In the present invention, the organic solution reagent is preferably an ethanol-acetone mixed solution; the present invention does not specifically limit the amount of ethanol-acetone used, as long as it can remove the surfactant in the oil bath hot reaction liquid. In the present invention, the oil bath hot reaction liquid washing is preferably carried out under ultrasonic conditions; the present invention does not specifically limit the time and power of ultrasound, and can be adjusted as needed. In an embodiment of the present invention, the number of organic solution washings is preferably 3 times. In the present invention, the number of water washings is preferably 2 times.

[0074] In the present invention, the drying temperature is preferably 60 to 90° C., more preferably 80 to 90° C.; the drying time is preferably 4 to 6 hours, more preferably 5 to 6 hours.

[0075] The preparation method of the palladium-platinum alloy mesoporous nanowires provided by the present invention is simple, and the prepared palladium-platinum alloy mesoporous nanowires have uniform diameter and mesopore distribution.

[0076] The present invention also provides the use of the palladium-platinum alloy mesoporous nanowires described in the above technical solution or the palladium-platinum alloy mesoporous nanowires prepared by the preparation method described in the above technical solution as a modification material for electrodes in electrochemical sensors.

[0077] The present invention does not impose any particular limitation on the application method, and any conventional application method of electrode modification materials may be used.

[0078] In the present invention, the preparation method of the application preferably includes: dispersing the palladium-platinum alloy mesoporous nanowires in water, and then applying them to the electrode surface; the present invention does not specifically limit the coating thickness of the palladium-platinum alloy mesoporous nanowires, and technical personnel in this field can choose according to actual needs.

[0079] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0080] Example 1

[0081] A palladium-platinum alloy mesoporous nanowire, wherein the average diameter of the palladium-platinum alloy mesoporous nanowire is 12 nm; the mesopores are distributed in the center of the palladium-platinum alloy mesoporous nanowire; the palladium and platinum in the palladium-platinum alloy mesoporous nanowire are alloy phases; the palladium exists in the state of Pd 3d (Pd 3d5 / 2 and Pd 3d3 / 2), and the platinum exists in the state of Pt 4f (Pt 4f7 / 2 and Pt4f5 / 2); the amount ratio of the palladium to the platinum is 1:5.

[0082] The preparation method of the palladium-platinum alloy mesoporous nanowires comprises the following steps:

[0083] (1) The preparation method of palladium nanowires is as follows: weigh 0.0177 g PdCl 2 , 1g polyvinyl pyrrolidone, 0.3g NaI are dissolved in 15mL ultrapure water, and completely dissolved by ultrasonic treatment to obtain a palladium-containing solution; the palladium-containing solution is transferred to a 25mL polytetrafluoroethylene-lined reactor, placed in a stainless steel reactor, and the muffle furnace is preheated to 220°C, and the reactor is placed in the muffle furnace for reaction for 3h. After the reaction is completed, it is taken out and cooled to room temperature; an acetone-ethanol mixed solution is used for purification twice, and the product is collected by centrifugation (9000rpm, 20min), and placed in a vacuum oven (70°C, 6h) for drying. The final product is palladium nanowires, recorded as PdNWs;

[0084] Weigh 0.020 g of ascorbic acid, 0.35 g of polyvinyl pyrrolidone, and 0.10 g of sodium iodide and dissolve them in 20 mL of hexylene glycol, then add a 0.38 mmol / L palladium nanowire solution (0.0008 g of palladium nanowires), and mix the solution evenly by ultrasonication at 9000 W for 10 min to obtain a precursor mixture;

[0085] (2) The precursor mixture obtained in step (1) is transferred to a 50 mL three-necked flask, placed in an oil bath at 110° C. for preheating for 20 min, and 5 mL of chloroplatinic acid (concentration of 8 mmol / L) is slowly added dropwise (1.5 mL / h) to the preheated precursor solution, while the temperature is raised from 110° C. to 190° C. After the solution is added, the mixture is reacted at 190° C. for 0.5 h; the oil bath hot reaction liquid is transferred to a 50 mL beaker, an ethanol-acetone mixed solution is added, and ultrasonic washing is performed for 20 min. The ultrasonic oil bath hot reaction liquid is then centrifuged at 6000 r / min for 15 min. The obtained precipitate is washed twice with an ethanol-acetone mixed solution, and then washed twice with deionized water, and finally dried at 90° C. for 4 h to obtain palladium-platinum alloy mesoporous nanowires.

[0086] Figure 1 TEM image of palladium-platinum alloy mesoporous nanowires provided in this embodiment, from Figure 1 It can be seen that the average diameter of the prepared palladium-platinum alloy mesoporous nanowires is about 12 nm.

[0087] Example 2

[0088] A palladium-platinum alloy mesoporous nanowire, wherein the average diameter of the palladium-platinum alloy mesoporous nanowire is 18 nm; the mesopores are distributed in the center of the palladium-platinum alloy mesoporous nanowire; the palladium and platinum in the palladium-platinum alloy mesoporous nanowire are alloy phases; the palladium exists in the state of Pd 3d (Pd 3d5 / 2 and Pd 3d3 / 2), and the platinum exists in the state of Pt 4f (Pt 4f7 / 2 and Pt 4f5 / 2); the amount ratio of the palladium to the platinum is 1:6.

[0089] The preparation method of the palladium-platinum alloy mesoporous nanowires comprises the following steps:

[0090] (1) Weigh 0.030 g of ascorbic acid, 0.65 g of polyvinyl pyrrolidone, and 0.20 g of sodium iodide and dissolve them in 20 mL of hexylene glycol, then add a palladium nanowire solution with a concentration of 0.66 mmol / L (the palladium nanowire is 0.0014 g), and mix the solution evenly under ultrasonic conditions at 9000 W for 10 min to obtain a precursor mixture;

[0091] (2) The precursor mixture obtained in step (1) is transferred to a 50 mL three-necked flask, placed in an oil bath at 110° C. for preheating for 20 min, and 5 mL of chloroplatinic acid (concentration of 16 mmol / L) is slowly added dropwise (1.5 mL / h) to the preheated precursor solution, while the temperature is raised from 110° C. to 210° C. After the solution is added, the mixture is reacted at 210° C. for 1.5 h; the oil bath hot reaction liquid is transferred to a 50 mL beaker, an ethanol-acetone mixed solution is added for ultrasonic washing for 20 min, and the oil bath hot reaction liquid after ultrasonic washing is centrifuged at 6000 r / min for 15 min. The obtained precipitate is washed twice with an ethanol-acetone mixed solution, and then washed twice with deionized water, and finally dried at 70° C. for 6 h to obtain palladium-platinum alloy mesoporous nanowires.

[0092] Figure 2 TEM image of palladium-platinum alloy mesoporous nanowires provided in this embodiment, from Figure 2 It can be seen that the average diameter of the prepared palladium-platinum alloy mesoporous nanowires is about 18 nm.

[0093] Example 3

[0094] A palladium-platinum alloy mesoporous nanowire, wherein the average diameter of the palladium-platinum alloy mesoporous nanowire is 15 nm; the mesopores are distributed in the center of the palladium-platinum alloy mesoporous nanowire; the palladium and platinum in the palladium-platinum alloy mesoporous nanowire are alloy phases; the palladium exists in the state of Pd 3d (Pd 3d5 / 2 and Pd 3d3 / 2), and the platinum exists in the state of Pt 4f (Pt 4f7 / 2 and Pt 4f5 / 2); the amount ratio of the palladium to the platinum is 1:2.

[0095] The preparation method of the palladium-platinum alloy mesoporous nanowires comprises the following steps:

[0096] (1) Weighing 0.025 g of ascorbic acid, 0.55 g of polyvinyl pyrrolidone, and 0.15 g of sodium iodide, dissolving them in 20 mL of hexylene glycol, then adding a palladium nanowire solution having a concentration of 0.47 mmol / L (0.001 g of palladium nanowire), and ultrasonically mixing the solution at 9000 W for 10 min to obtain a precursor mixture;

[0097] (2) The precursor mixture obtained in step (1) is transferred to a 50 mL three-necked flask, placed in an oil bath at 110° C. for preheating for 20 min, and 5 mL of chloroplatinic acid (concentration of 4 mmol / L) is slowly added dropwise (1.5 mL / h) to the preheated precursor solution, while the temperature is raised from 110° C. to 200° C. After the solution is added, the mixture is reacted at 200° C. for 1 h; the oil bath hot reaction liquid is transferred to a 50 mL beaker, an ethanol-acetone mixed solution is added for ultrasonic washing for 20 min, and the oil bath hot reaction liquid after ultrasonic washing is centrifuged at 6000 r / min for 15 min, the obtained precipitate is washed twice with an ethanol-acetone mixed solution, and then washed twice with deionized water, and finally dried at 60° C. for 4 h to obtain palladium-platinum alloy mesoporous nanowires.

[0098] Figure 3 TEM image of palladium-platinum alloy mesoporous nanowires provided in this embodiment, from Figure 3 It can be seen that the average diameter of the prepared palladium-platinum alloy mesoporous nanowires is about 15nm. The length is between hundreds of nanometers and micrometers, and the pore size distribution is between 2.3nm and 5.6nm, which is mesoporous. The TEM image is very clear, indicating that the palladium-platinum alloy mesoporous nanowires have good conductivity, which can prove that the palladium-platinum alloy mesoporous nanowires prepared by this method have a clean surface and do not affect the conductivity of the metal.

[0099] Comparative Example 1

[0100] A method for preparing palladium nanowires is as follows: weigh 0.0177 g PdCl 2 , 1g polyvinyl pyrrolidone, and 0.3g NaI are dissolved in 15mL ultrapure water, and completely dissolved by ultrasonic treatment to obtain a palladium-containing solution; the palladium-containing solution is transferred to a 25mL polytetrafluoroethylene-lined reactor, placed in a stainless steel reactor, and the muffle furnace is preheated to 220°C. The reactor is placed in the muffle furnace to react for 3h. After the reaction is completed, it is taken out and cooled to room temperature; an acetone-ethanol mixed solution is used for purification twice, and the product is collected by centrifugation (9000rpm, 20min), and placed in a vacuum oven (70°C, 6h) for drying. The final product is palladium nanowires, recorded as PdNWs.

[0101] Application Example 1

[0102] An enzyme electrode modified with palladium-platinum alloy mesoporous nanowires, the preparation method of which is as follows:

[0103] (1) The glassy carbon electrode was polished with 300 nm and 50 nm alumina powders, ultrasonically cleaned in acetone, ethanol, and ultrapure water for 30 s respectively, and dried with nitrogen for later use;

[0104] (2) The palladium-platinum alloy mesoporous nanowires provided in Example 1 were dispersed in water to obtain a dispersion with a concentration of 1.5 mg / mL, and 8 μL of the palladium-platinum alloy mesoporous nanowires were transferred using a 10 μL micropipette and dropped onto the surface of the glassy carbon electrode, and then placed at room temperature to dry;

[0105] (3) Use a 10 μL micropipette to transfer 1.25 μL of AChE solution (0.2 U / μL) and 2 L of CS solution (0.5 wt%) and mix them evenly;

[0106] (4) The mixed solution is evenly coated on the surface of the glassy carbon electrode modified with palladium-platinum alloy mesoporous nanowires, and placed at 4°C to dry for later use.

[0107] Application Example 2

[0108] A palladium-platinum alloy mesoporous nanowire-modified enzyme electrode is different from Application Example 1 in that the palladium-platinum alloy mesoporous nanowire prepared in Example 2 is used, and the remaining steps are the same as those in Application Example 1.

[0109] Application Example 3

[0110] A palladium-platinum alloy mesoporous nanowire-modified enzyme electrode is different from Application Example 1 in that the palladium-platinum alloy mesoporous nanowire prepared in Example 3 is used, and the remaining steps are the same as those in Application Example 1.

[0111] Comparative application example 1

[0112] A palladium nanowire-modified enzyme electrode is different from Application Example 1 in that the palladium nanowire prepared in Comparative Example 1 is used, and the remaining steps are the same as those in Application Example 1.

[0113] Comparative Application Example 2

[0114] An enzyme electrode, which is different from Application Example 1 in that palladium-platinum alloy mesoporous nanowires are not added, and the remaining steps are the same as those of Application Example 1.

[0115] Test Case

[0116] (1) Using CV test, by changing the scan rate, the response current at different scan rates was obtained. Based on the linear relationship between the current and the square root of the scan rate, the electrochemical active area of ​​the palladium-platinum alloy mesoporous nanowire modified electrode was studied, and the CV curve of the electrode prepared in Application Example 1 was obtained as shown in FIG. Figure 4 As shown, the linear fitting diagram is Figure 5 As shown; the CV curve of the electrode prepared in Application Example 2 is as shown Figure 6 As shown, the linear fitting diagram is Figure 7 As shown; the CV curve of the electrode prepared in Application Example 3 is as shown Figure 8 As shown, the linear fitting diagram is Fig. 9As shown. By calculation, the electrochemical active area (ECSA) of the electrode prepared in Application Example 1 is 0.145 cm 2 The electrochemically active area (ECSA) of the electrode prepared in Application Example 2 is 0.194 cm 2 The electrochemically active area (ECSA) of the electrode prepared in Application Example 3 is 0.232 cm 2 This indicates that the palladium-platinum alloy mesoporous nanowire modified electrode provided by the present invention has excellent electrocatalytic activity.

[0117] (2) The XRD pattern of the palladium-platinum alloy mesoporous nanowires provided in Example 3 is as follows Fig.10 As shown, the EDS diagram is Fig.11 As shown. Figures 10-11 It can be seen that the peak in the XRD graph is between the peaks of standard palladium (Pd JCPDS No. 46-1043) and platinum (Pt JCPDS No. 01-1190), indicating that palladium and platinum form an alloy, and the elements present in the palladium-platinum alloy mesoporous nanowires are palladium and platinum.

[0118] (3) The XPS image of the palladium-platinum alloy mesoporous nanowires provided in Example 3 is as follows Fig.12 As shown. Fig.12 It can be seen that palladium and platinum in the palladium-platinum alloy mesoporous nanowire sample prepared in the present invention exist in the state of Pd 3d (Pd 3d5 / 2 and Pd 3d3 / 2) and Pt 4f (Pt 4f7 / 2 and Pt 4f5 / 2).

[0119] (4) The electrochemical properties of electrodes modified with different materials were studied and analyzed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Both cyclic voltammetry and electrochemical impedance spectroscopy tests were conducted in a 5 mmol / L potassium ferrocyanide / potassium ferrocyanide solution containing 0.1 mol / L potassium chloride. The voltage test range of the cyclic voltammetry test was -0.2V to 0.6V, and the scan rate was 0.1V / s; the electrochemical impedance spectroscopy test frequency was 100KHz to 0.01Hz, and the amplitude was 0.005V. The CV curves of electrodes modified with different materials are shown in the figure below. Fig.13 As shown, the EIS curve is Fig.14 As shown. Figures 13-14Among them, AChE-CS / GCE is the electrode prepared in comparative application example 2, and its electron transfer resistance is 1088Ω; bare GCE is an empty glassy carbon electrode, and its electron transfer resistance is 408Ω; PdNWs / GCE is a glassy carbon electrode modified with palladium nanowires, and its electron transfer resistance is 251Ω; PdPt alloy MNWs / GCE is a glassy carbon electrode modified with palladium platinum alloy mesoporous nanowires, and its electron transfer resistance is 135Ω; AChE-CS / PdPt alloy MNWs / GCE is an electrode prepared in application example 3, and its electron transfer resistance is 733Ω. It can be seen that the conductivity of the electrode prepared by the palladium platinum alloy mesoporous nanowires prepared in this embodiment is better than that of palladium alone, and their conductivity is better than that of platinum carbon electrodes alone.

[0120] (5) The electrodes prepared in Application Example 1, Comparative Application Example 1 and Comparative Application Example 2 were used to study the current response of different enzyme electrodes to 4 mmol / L substrate ATCh using differential pulse voltammetry. The results are as follows: Fig.15 As shown. Fig.15 In the figure, the arrows are in the order of curves a, b, c and d. Curve a is the enzyme electrode prepared in Application Example 3, curve b is the enzyme electrode prepared in Comparative Application Example 1, curve c is the enzyme electrode prepared in Comparative Application Example 2, and curve d is the DPV response curve when there is no substrate. Fig.15 It can be seen that the enzyme electrode modified with palladium-platinum alloy mesoporous nanowires has the largest response current to the substrate. This is not only due to the synergistic effect of the PdPt alloy bimetallic to enhance its conductivity, but also benefits from the active sites exposed by the mesoporous nanowire structure, which can produce a stronger adsorption effect on AChE while maintaining the activity of the enzyme to the greatest extent.

[0121] It can be seen from the above results that the enzyme electrode modified with the palladium-platinum alloy mesoporous nanowires provided by the present invention has excellent electrocatalytic activity. This is because the palladium-platinum alloy mesoporous nanowires provided by the present invention contain metal palladium and platinum. After the two metal elements form an alloy, a synergistic effect can be produced, the active surface area can be increased, and the conductivity can be improved; it can be used as a modification material for electrodes in electrochemical sensors to improve the electrocatalytic activity of the electrodes.

[0122] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A palladium-platinum alloy mesoporous nanowire, wherein the average diameter of the palladium-platinum alloy mesoporous nanowire is 12 to 18 nm; and the mesopores of the palladium-platinum alloy mesoporous nanowire are distributed in the center; The palladium and platinum in the palladium-platinum alloy mesoporous nanowires are in an alloy phase; the palladium exists in a Pd 3d state, and the platinum exists in a Pt4f state; the amount ratio of the palladium to the platinum is (1-3):(1-6).

2. The method for preparing the palladium-platinum alloy mesoporous nanowires according to claim 1, comprising the following steps: (1) mixing a reducing agent, a surfactant, a structure directing agent, palladium nanowires, and a solvent to obtain a precursor mixture; (2) After preheating the precursor mixed solution obtained in step (1), the platinum source solution is added dropwise to the preheated precursor solution to perform a reduction reaction to obtain palladium-platinum alloy mesoporous nanowires.

3. The preparation method according to claim 2, characterized in that: The reducing agent in step (1) includes ascorbic acid or glucose.

4. The preparation method according to claim 2, characterized in that: The surfactant in step (1) includes polyvinyl pyrrolidone or hexadecyltrimethylammonium bromide.

5. The preparation method according to claim 2, characterized in that: The structure directing agent in step (1) includes sodium iodide, polyvinyl pyrrolidone, polyvinyl alcohol or polyethylene glycol.

6. The preparation method according to claim 2, characterized in that: The average diameter of the palladium nanowires in step (1) is 6 to 12 nm.

7. The preparation method according to claim 2, characterized in that: The mass ratio of the reducing agent, surfactant, structure directing agent and palladium nanowire in the step (1) is (0.020-0.030): (0.25-0.65): (0.10-0.20): (0.00050-0.0015).

8. The preparation method according to claim 2, characterized in that: The rate of dropping the platinum source solution in step (2) is 0.5 to 2 mL / h.

9. The preparation method according to claim 2, characterized in that: The temperature of the reduction reaction in step (2) is 110-210° C., and the time of the reduction reaction is 0.5-1.5 h.

10. Use of the palladium-platinum alloy mesoporous nanowires according to claim 1 or the palladium-platinum alloy mesoporous nanowires prepared by the preparation method according to any one of claims 2 to 9 as a modification material for electrodes in electrochemical sensors.

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