Preparation method and application of flower-shaped flexible platinum counter electrode

Abstract

The invention belongs to the technical field of electrochemical electrode preparation, and discloses a preparation method and application of a flower-shaped flexible platinum counter electrode. The preparation method comprises the following steps: coating a flexible substrate modified by a hydrophilic layer with AgNWs to obtain an AgNWs electrode, putting the electrode into a mixed electrolyte solution, and carrying out electrochemical deposition to obtain the flower-shaped PtNPs / AgNWs flexible counter electrode. The counter electrode provided by the invention effectively overcomes the inherent defects of the traditional graphite carbon rod, platinum wire and platinum sheet counter electrode. The electrode is also easy to prepare and integrate a small flexible electrochemical device, and provides technical support for developing a micro flexible electrochemical sensor.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical electrode preparation, and particularly relates to a preparation method and application of a flower-shaped flexible platinum counter electrode. Background Art

[0002] With the rapid development of electronic technology, the flexibility of electronic devices has become an irresistible trend. Flexible sensors, with the characteristic of conforming to complex curved surfaces, achieve precise perception in fields such as industrial monitoring and environmental detection; stretchable solar cells, as a clean energy supply end, stably power devices in remote areas; and flexible displays reshape the information interaction method and are widely used in vehicle-mounted and portable devices. The rapid development of these cutting-edge fields has greatly stimulated the market demand for small flexible electrochemical devices, making the importance of high-performance flexible counter electrodes more prominent. In a three-electrode system, the counter electrode is a core component that collaborates with the working electrode to build a conduction path and drive electrochemical reactions. When an oxidation-reduction reaction occurs on the surface of the working electrode, the counter electrode acts as a charge carrier to complete the circuit closure. It not only needs to maintain low resistance to allow current to conduct smoothly but also has strong anti-polarization ability to maintain signal stability, playing a decisive role in the stable operation of the entire electrochemical system. Applying it to electrochemical detection and catalysis not only conforms to the trend of flexible electronic devices, improves the performance and stability of devices, but also provides support for the large-scale application of flexible electrochemical devices in fields such as the Internet of Things and artificial intelligence, further expanding the application boundaries of flexible electronic technology.

[0003] In the field of flexible counter electrodes, the current research situation is not optimistic and is almost blank. Although there are a small number of related patents and academic achievements, truly excellent flexible and highly integrated counter electrodes are still hard to find. There are already commercially available graphite counter electrodes prepared by flexible printing, but such electrodes still cannot get rid of the common problems of graphite carbon rods, with poor chemical stability. In extreme environments such as high temperature, high humidity, or strong acids and bases, the electrode performance will deteriorate rapidly. The lack of biocompatibility also makes it difficult to play a role in in-vivo detection scenarios. Some researchers have tried to improve the performance of counter electrodes through technological innovation. For example, Fu Nianqing et al. used ultraviolet photocatalytic reduction technology to load PtNPs on the surface of a flexible polymer conductive substrate (ITO-PEN). When the concentration of chloroplatinic acid is higher than 0.15 mM, the composite electrode exhibits good catalytic activity. However, the existing substrate brittleness problem still hinders the application of this achievement in actual flexible devices. In the field of electrochemical detection and catalysis, the development of flexible integrated devices urgently demands flexible counter electrodes. However, currently, there is no flexible counter electrode that can be adapted to flexible integrated devices in this field.

[0004] Currently, there is no invention of flexible Pt counter electrodes, and this technological gap has greatly restricted the R & D and application of flexible electrochemical devices. R & D personnel urgently need a counter electrode that not only has excellent electrochemical performance and acid-base corrosion resistance, but also can withstand bending, stretching, and has long-term stability, so as to promote the integration and development of flexible electrochemical devices. Such electrodes can not only meet the special requirements of flexible devices for material flexibility, but also operate stably in complex working environments, laying a solid foundation for the large-scale application of flexible electrochemical devices in cutting-edge fields such as wearable devices, portable medical instruments, and environmental monitoring sensors. Summary of the Invention

[0005] In order to overcome the deficiencies in performance of commercial hard graphite carbon rods, platinum wires, platinum sheets, etc. as counter electrodes in the prior art, the present invention provides a preparation method and application of a flower-shaped flexible platinum counter electrode. The prepared flower-shaped PtNPs / AgNWs counter electrode has high stability and strong conductivity. This flexible electrode has a low sheet resistance and can still maintain good conductivity after being bent multiple times and stretched to a certain extent, meeting the characteristics of flexibility.

[0006] The above object of the present invention is achieved by the following technical solutions: A preparation method of a flower-shaped flexible platinum counter electrode, the steps are as follows:

[0007] 1. Immerse AgNWs in methanol, and then clean them with ozone. The treated AgNWs solution is spin-coated, spray-coated or coated on a flexible substrate modified with a hydrophilic layer to obtain an AgNWs electrode;

[0008] 2. Place the AgNWs electrode in a mixed electrolyte solution of K2PtCl4, H2SO4 and K2SO4, and perform electrochemical deposition by chronoamperometry. After deposition, a flower-shaped PtNPs / AgNWs flexible counter electrode is obtained.

[0009] Further, in step 1, AgNWs are immersed in methanol 3 times, then cleaned with ozone for ten minutes, the concentration of the AgNWs solution is 0.1 - 5 mg / ml, and the spin-coating speed is 100 - 10000 rpm.

[0010] A further preference of the present invention is that in step 1, the concentration of the AgNWs solution is 1.0 mg / ml, and the spin-coating speed is 3000 rpm.

[0011] Further, in step 2, the concentration of K2PtCl4 is 1 - 100 mmol / L, the concentration of H2SO4 is 1 - 1000 mmol / L, and the concentration of K2SO4 is 1 - 500 mmol / L.

[0012] Further preferably in the present invention, in step 2, the concentration of K2PtCl4 is 5 mmol / L, the concentration of H2SO4 is 50 mmol / L, and the concentration of K2SO4 is 50 mmol / L.

[0013] Further, in step 2, chronoamperometry is used for electrochemical deposition, where the deposition time is 100 - 5000 s and the deposition potential range is (-0.5) - (+0.5) V.

[0014] Further preferably in the present invention, in step 2, the electrochemical deposition time is set to 4000 s and the deposition potential is set to -0.2 V.

[0015] Another object of the present invention is to protect the flower-shaped flexible platinum counter electrode prepared by the above-mentioned method for preparing a flower-shaped flexible platinum counter electrode.

[0016] Another object of the present invention is to protect the application of the above-mentioned flower-shaped flexible platinum counter electrode.

[0017] Further, the application specifically includes: the application of the flower-shaped flexible platinum counter electrode in the electrochemical catalysis and detection of ethanol, the application of the flower-shaped flexible platinum counter electrode in the electrocatalysis of sucrose, and the application of the flower-shaped flexible platinum counter electrode in the synchronous detection of dopamine and adrenaline in a flexible electrochemical sensor.

[0018] The beneficial effects of the present invention compared with the prior art are:

[0019] The counter electrode adopts a novel flower-shaped nano-platinum structure, which is different from the traditional rigid counter electrode and has advantages such as tensile resistance, bending resistance, and corrosion resistance, and can better adapt to complex application scenarios, expanding the scope of use of the counter electrode in the electrochemical field.

[0020] The present invention has the advantage of improved electrode performance: the counter electrode uses PDMS or PI as the electrode substrate material, which has the characteristics of flexibility and elasticity; silver nanowires are used as the conductive layer and PtNPs are used as the nano-electrode material for the electrochemical deposition layer. Through the composite structure design with flower-shaped nano-platinum on the outer layer and silver nanowires with good conductivity on the inner layer, both the stability of the electrode (platinum element on the outside and stable) and the conductivity of the electrode (good conductivity of silver nanowires, wrapped inside) are ensured, improving the overall performance of the electrode.

[0021] The present invention embodies the characteristics of material optimization: the composite structure composed of flower-shaped nano-platinum and silver nanowires not only has excellent conductivity but also good biocompatibility. Silver nanowires are used internally, which can significantly improve conductivity while having little impact on the overall electrode material, ensuring the stability of the electrode's other performance aspects and achieving the efficient utilization of material properties. Moreover, the electrochemical deposition method used in the present invention for preparing the nano-platinum conductive layer has the greatest advantage of being simple and easy to implement with good repeatability. At the same time, it can overcome the difficulties encountered in the synthesis and separation of nano-platinum, with a simple preparation process and easy mass production.

[0022] The present invention helps to integrate flexible electrochemical sensors: traditional rigid counter electrodes are difficult to achieve the integration of a three-electrode system. However, the flexible counter electrode of the present invention, with its bendable and deformable characteristics, can flexibly adapt to various complex shapes and narrow spaces, providing the possibility for integration with other electronic components. During the integration process, it can stably combine with other materials or components, effectively avoiding integration problems caused by material mismatch and ensuring the stable operation of the integrated system.

[0023] In summary, the counter electrode provided by the present invention effectively overcomes the inherent defects of traditional graphite carbon rods, platinum wires, and platinum sheet counter electrodes. The flower-shaped flexible Pt counter electrode prepared by the method of the present invention shows significant improvement in both electrochemical performance and mechanical stability. At the same time, it has acid and alkali corrosion resistance and excellent flexibility, and its performance can be comparable to that of commercial counter electrodes. It can be applied to the efficient catalysis and detection of sucrose and the simultaneous detection of dopamine and epinephrine. In addition, this electrode is also easy to prepare and integrate into small flexible electrochemical devices, providing technical support for the development of micro flexible electrochemical sensors. Description of the Drawings

[0024] The present invention will be further described below in conjunction with the drawings and specific embodiments

[0025] Figure 1 is the flow chart of the preparation method of the flower-shaped flexible Pt counter electrode of the present invention;

[0026] Figure 2 is the SEM image of the flower-shaped PtNPs / AgNWs flexible counter electrode of the present invention;

[0027] Figure 3 is the OCP test of the prepared flower-shaped PtNPs / AgNWs flexible counter electrode placed in H2SO4, PBS, and KOH solutions with a concentration of 1mol / L respectively;

[0028] Figure 4 is the stability test of the flower-shaped PtNPs / AgNWs flexible counter electrode;

[0029] Figure 5 is the reproducibility test of the flower-shaped PtNPs / AgNWs flexible counter electrode;

[0030] Figure 6 Cyclic voltammogram comparison diagram of the flower-shaped PtNPs / AgNWs flexible counter electrode, commercial hard platinum wire, platinum sheet, and graphite carbon rod CE for catalyzing ethanol;

[0031] Figure 7 Cyclic voltammogram of the flower-shaped PtNPs / AgNWs flexible counter electrode of the embodiment of the present invention for catalyzing 0.9 M sucrose;

[0032] Figure 8 Differential pulse voltammetry (DPV) curve of the flower-shaped PtNPs / AgNWs flexible counter electrode of the embodiment of the present invention for simultaneously detecting dopamine and epinephrine;

[0033] Figure 9 Test results of the tensile resistance performance of the flower-shaped PtNPs / AgNWs flexible counter electrode of the embodiment of the present invention;

[0034] Figure 10 Test results of the bending resistance of the flower-shaped PtNPs / AgNWs flexible counter electrode of the embodiment of the present invention. Detailed implementation manners

[0035] The present invention will be described in detail below through specific embodiments, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained from commercial channels.

[0036] The preparation method of the flower-shaped PtNPs / AgNWs flexible counter electrode in the following embodiments is as follows:

[0037] Step 1: Prepare the AgNWs conductive layer. Soak the AgNWs in methanol three times, and then clean them with ozone for 10 minutes. Using a mixed solution of absolute ethanol and water (5:5, V / V) as the solvent, prepare a 1 mg / ml silver nanowire solution with the pretreated AgNWs. The specifications of the silver nanowires are: diameter 90 nm, length 60 μm. Spread it evenly in the grooves on the surface of the flexible substrate and place it at room temperature to dry for one day;

[0038] Step 2: Preparation of flower-shaped PtNPs / AgNWs flexible counter electrode. A three-electrode system composed of an AgNWs flexible electrode as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum wire as the counter electrode was placed in a mixed electrolyte solution containing 5 mmol / L K2PtCl4, 50 mmol / L H2SO4, and 50 mmol / L K2SO4. Chronoamperometry (i-t method) was used for potentiostatic deposition. Potentiostatic deposition was carried out using the i-t method of an electrochemical workstation. The deposition voltage was -0.2 V, and the deposition time was 4000 s. It was left to dry at room temperature for one day, and the flower-shaped PtNPs / AgNWs flexible counter electrode was prepared.

[0039] The surface morphology diagram of the flower-shaped PtNPs / AgNWs flexible counter electrode is as Figure 2 shown. The electrodeposited Pt presents many sheet-like structures with tip-shaped flowers. This is because during the electroreduction process, by applying additional electrons to potassium chloroplatinate, zero-valent Pt atoms are formed in the solution. PtNPs continuously accumulate on the AgNWs conductive layer. PtNPs tend to cluster and aggregate, resulting in a relatively small distance between adjacent clusters. This morphology has a large specific surface area, which can provide more sites, is conducive to electron transport, and thus reduces the electrode resistance. It can be preliminarily judged from the above that the performance of this new type of counter electrode is good.

[0040] Example 1 OCP test of flower-shaped PtNPs / AgNWs flexible counter electrode in acidic, neutral, and alkaline solutions

[0041] To verify the stability of the flower-shaped PtNPs / AgNWs flexible counter electrode under acidic and alkaline conditions, continuous long-term testing of this electrode was carried out using the electrochemical open-circuit potential mode. The prepared counter electrode was respectively placed into 1 mol / L H2SO4, PBS, and KOH and connected to a saturated calomel electrode RE to form a two-electrode system for testing. The results are as Figure 3 shown. In the three solutions, the OCPT curves of this counter electrode are very stable at 10000 s, all near 0 V and with little difference. It can be seen from this that the counter electrode prepared by the present invention has excellent stability against acid and alkali corrosion.

[0042] Example 2 Stability and reproducibility test of flower-shaped PtNPs / AgNWs flexible counter electrode at room temperature

[0043] To verify the stability of the prepared counter electrode at room temperature, four-point probe resistance tests were carried out every week. The test results are as Figure 4 shown. It was found that as time increased, the resistance of the electrode changed little, and its RSD was 1.44%. To verify the reproducibility of this electrode at room temperature, six electrodes were placed in a 5 mM potassium ferricyanide solution for testing. The results are as Figure 5As shown, it is found that the sheet resistance of the electrode changes little with time, and its RSD is 0.47%. Thus, it can be proved that the flower-like PtNPs / AgNWs flexible counter electrode of the present invention has good long-term stability and reproducibility.

[0044] Comparative Example 1

[0045] The flower-like PtNPs / AgNWs flexible counter electrode was applied to the catalysis of ethanol and then compared with a commercial rigid counter electrode.

[0046] Figure 6 Figure 6 is a comparative cyclic voltammogram of the flower-like PtNPs / AgNWs flexible counter electrode, a commercial rigid platinum wire, a platinum sheet, and a graphite carbon rod CE for the catalysis of ethanol. Using the Ni-CuO / ITO electrode as the working electrode and the saturated calomel electrode as the reference electrode, and using the self-made flower-like PtNPs / AgNWs flexible counter electrode and a commercial rigid platinum wire, a platinum sheet, and a graphite carbon rod as the counter electrodes respectively, cyclic voltammetry was used to catalyze ethanol. The experimental results are as shown in Figure 6. Their oxidation peaks are similar, but there are obvious differences in the catalytic effects. Among them, the current density of the flower-like PtNPs / AgNWs flexible counter electrode is the largest, which is 23.19 mA / cm -2 , indicating that the catalytic response effect of the flower-like PtNPs / AgNWs flexible counter electrode of the present invention is significantly better than that of other commercial counter electrodes of the same area.

[0047] Application Example 1

[0048] The flower-like PtNPs / AgNWs flexible counter electrode was applied to the catalysis of sucrose.

[0049] The flower-like PtNPs / AgNWs flexible counter electrode is easy to integrate and can be used for the electrocatalytic reaction of sucrose. In this experiment, CV method was used for sucrose detection. The WE was the Pt / Ni / Ag flexible electrode, the RE was the saturated calomel electrode, and the CE was the flower-like PtNPs / AgNWs flexible electrode. It was placed in a sucrose solution with a concentration of 0.9 M, and CV method was used for the electrocatalytic reaction of sucrose. The obtained cyclic voltammogram is as Figure 7 shown. An oxidation peak of sucrose appeared near 0.45 V, and the detection current was 7.49 mA. Thus, it can be seen that the flower-like PtNPs / AgNWs flexible counter electrode can be applied to small flexible electrochemical devices, can be used for sucrose catalysis and detection, and provides a possibility for the integration of small flexible electrochemical devices.

[0050] Application Example 2

[0051] The flower-like PtNPs / AgNWs flexible counter electrode was applied to the simultaneous detection of dopamine and epinephrine.

[0052] The flower-like PtNPs / AgNWs flexible counter electrode is easy to integrate and can achieve the synchronous detection of dopamine and epinephrine. In this experiment, differential pulse voltammetry (DPV) was used to detect dopamine and epinephrine. The working electrode (WE) was an Au / Ni electrode, the reference electrode (RE) was a saturated calomel electrode, and the counter electrode (CE) was a flower-like PtNPs / AgNWs flexible electrode. It was placed in a mixed solution with a dopamine concentration of 1 M and an epinephrine concentration of 1 M, and tested by DPV method. The obtained DPV curves are as Figure 8 shown. A detection peak of DA appears at about 0.15 V, and the peak current is about 343 μA. An EP detection peak appears at about 0.45 V, and the peak current is about 364 μA. It can be seen that the flower-like PtNPs / AgNWs flexible counter electrode can be applied to small flexible electrochemical devices, and can be used for the synchronous detection of dopamine and epinephrine. This counter electrode provides another possibility for the integration of small flexible electrochemical devices.

[0053] The prepared flower-like PtNPs / AgNWs flexible counter electrode was subjected to a tensile resistance test. After the counter electrode was stretched by 3%, 6%, 9%, 12%, and 15% respectively, the relative change in R / R0 was measured and compared with the resistance of the electrode before stretching. The test results are as Figure 8 shown. As the amplitude of the tensile strength increases, the electrode resistance shows a slightly increasing trend. The relative standard deviation of the R / R0 value is 5.29%, and the overall change is not significant, indicating that the counter electrode has good tensile resistance.

[0054] The prepared flower-like PtNPs / AgNWs flexible counter electrode was subjected to a bending resistance test. After the counter electrode was bent at 30°, 60°, 90°, 120°, and 150°, the relative change in R / R0 was measured and compared with the resistance of the electrode before bending. The test results are as Figure 9 shown. As the bending angle increases, the electrode resistance shows a slightly increasing trend. The relative standard deviation of the R / R0 value is 2.99%, and the electrical performance does not show fatigue or significant decline, indicating the excellent bending resistance of the counter electrode.

[0055] In summary, in the present invention, PDMS or PI is used to fabricate the flexible substrate of the counter electrode, and AgNWs endow the counter electrode with good conductivity. Compared with commercial graphite carbon rod, platinum wire, and platinum sheet electrodes, the ethanol oxidation peak current is increased. The present invention simplifies the experimental steps, has high repeatability, and the fabricated flexible counter electrode has higher conductivity and stronger stability. The electrode product can be comparable to commercial counter electrodes, and the electrode shows high sensitivity when applied to the catalysis of sucrose and the synchronous detection of dopamine and epinephrine, and has practicality in the integration of small flexible electrochemical sensors. The performance of the flower-like PtNPs / AgNWs flexible counter electrode prepared by the method of the present invention is at the leading level in the same industry, and has good application prospects in the miniaturization and integration of flexible electronic devices.

[0056] The above-described embodiments are only the preferred embodiments of the present invention, rather than all the feasible embodiments of the present invention. Any obvious modifications made by those of ordinary skill in the art without departing from the principle and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A preparation method of a flower-shaped flexible platinum counter electrode, characterized in that, The steps are as follows: S1. Immerse AgNWs in methanol, then clean them with ozone. The processed AgNWs solution is spin-coated, spray-coated or coated on a flexible substrate modified with a hydrophilic layer to obtain an AgNWs electrode; S2. Place the AgNWs electrode in a mixed electrolyte solution of K2PtCl4, H2SO4 and K2SO4, and perform electrochemical deposition using chronoamperometry. After deposition, a flower-shaped PtNPs / AgNWs flexible counter electrode is obtained.

2. The preparation method of the flower-shaped flexible platinum counter electrode according to claim 1, characterized in that, In step S1, AgNWs are immersed in methanol three times, then cleaned with ozone for ten minutes. The concentration of the AgNWs solution is 0.1 - 5 mg / ml, and the spin-coating speed is 100 - 10,000 rpm.

3. The preparation method of the flower-shaped flexible platinum counter electrode according to claim 2, characterized in that, In step S1, the concentration of the AgNWs solution is 1.0 mg / ml, and the spin-coating speed is 3000 rpm.

4. The preparation method of the flower-shaped flexible platinum counter electrode according to claim 1, wherein, In step S2, the concentration of K2PtCl4 is 1 - 100 mmol / L, the concentration of H2SO4 is 1 - 1000 mmol / L, and the concentration of K2SO4 is 1 - 500 mmol / L. In step S2, electrochemical deposition is performed using chronoamperometry, where the deposition time is 100 - 5000 s, and the deposition potential range is (-0.5) - (+0.5) V.

5. The preparation method of the flower-shaped flexible platinum counter electrode according to claim 4, wherein, In step S2, the concentration of K2PtCl4 is 5 mmol / L, the concentration of H2SO4 is 50 mmol / L, and the concentration of K2SO4 is 50 mmol / L. The electrochemical deposition time is set to 4000 s, and the deposition potential is set to -0.2 V.

6. A flower-shaped flexible platinum counter electrode, characterized in that, It is prepared by the preparation method of the flower-shaped flexible platinum counter electrode as described in claim 1.

7. The application of the flower-shaped flexible platinum counter electrode as described in claim 6.

8. The application of the flower-shaped flexible platinum counter electrode according to claim 7, characterized in that, Specifically, it includes the application of the flower-shaped flexible platinum counter electrode in the electrocatalysis and detection of ethanol.

9. The application of the flower-shaped flexible platinum counter electrode according to claim 7, characterized in that, Specifically, it includes the application of the flower-shaped flexible platinum counter electrode in the electrocatalysis of sucrose.

10. The application of the flower-shaped flexible platinum counter electrode according to claim 7, characterized in that, Specifically, it includes the application of the flower-shaped flexible platinum counter electrode in the synchronous detection of dopamine and epinephrine in a flexible electrochemical sensor.

Images