NO electrochemical sensor based on electrochemical dealloying platinum-cobalt bimetallic nano material and preparation method of NO electrochemical sensor

Abstract

The invention relates to an NO electrochemical sensor based on an electrochemical dealloying platinum-cobalt bimetallic nano material and a preparation method thereof. Platinum-cobalt alloy nanoparticles (dPtCo SP) are generated on the surface of an electrode in situ through an electrochemical deposition technology, and after Pt and Co form an alloy structure, part of Co is selectively removed by adopting an electrochemical dealloying technology, so that a nanoparticle interface with rich surface active sites is obtained. The sensor is simple and convenient in preparation method, low in cost and excellent in performance, and can meet the requirements of NO monitoring under physiological conditions. In addition, the sensor also has the advantages of high sensitivity, low detection limit, good stability, strong anti-interference capability and the like, and has important application value and commercial potential in the field of biomedical analysis and detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical sensors, and in particular relates to the application of electrochemically dealloyed platinum-cobalt bimetallic nanomaterials in constructing NO electrochemical sensors. Background Art

[0002] In the physiological environment, nitric oxide (NO), as a key mediator of nitrosative stress response, plays an important negative regulatory role in the development of various pathological injuries and diseases. This biological characteristic has prompted researchers to pay close attention to the study of the dynamic changes in NO production levels in cells and its conversion mechanism. NO is mainly produced in the mitochondrial electron transport chain. Its production process usually presents explosive characteristics and exhibits significant physicochemical properties such as high reactivity and short half-life (about a few seconds). After generation, NO molecules will undergo a series of dynamic processes such as transmembrane transport, redox reaction and free diffusion. However, due to its transient existence characteristics (short half-life) and limited diffusion distance (about 100-200μm), the development of analytical techniques that can achieve in situ real-time monitoring of NO still faces major challenges.

[0003] Methods for detecting NO mainly include colorimetry, spectrophotometry, spectroscopy, fluorescence, and electrochemical methods. Among them, electrochemical methods are particularly suitable for real-time detection of NO molecules due to their advantages such as high sensitivity, strong specificity, simple operation, and low cost. When constructing NO sensors, electrochemical dealloying treatment can effectively form a nanoporous structure, which not only significantly increases the specific surface area and the number of active sites of the material, but also enhances the electrocatalytic activity of platinum-based alloys (including platinum and non-precious metal alloys), while also improving the stability and durability of platinum-based catalysts to a certain extent. Therefore, NO electrochemical sensors based on electrochemical dealloyed nanomaterials show good application prospects.

[0004] The outermost d-electron orbitals of platinum group elements (PGMs) can coordinate with the lone pairs of electrons in NO molecules, enabling efficient NO adsorption. Furthermore, PGMs possess excellent physicochemical properties, such as high-temperature stability, low electrical resistance, and high corrosion resistance, which contribute to their exceptional performance in NO electrocatalytic sensing. However, as a precious metal, PGM is relatively expensive, necessitating the development of alternative metal components. This sensor, characterized by its simple fabrication method, low cost, and excellent performance, is expected to play an important role in biomedical analytical detection. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide an application of platinum-based nanomaterials in constructing a nitric oxide electrochemical sensor.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A NO electrochemical sensor based on electrochemical dealloyed platinum-cobalt bimetallic nanomaterial and a preparation method thereof.

[0008] Preferably, the nitric oxide electrochemical sensor comprises an electrochemical workstation, a working electrode whose surface is modified with electrochemically dealloyed platinum-cobalt bimetallic nanomaterials, a matching counter electrode, a reference electrode, an electrolytic cell and an electrolyte.

[0009] Preferably, the working electrode, whose surface is modified with electrochemically dealloyed platinum-cobalt bimetallic nanomaterials, is prepared as follows: the electrode is immersed in an electrolyte containing potassium chloroplatinite, cobalt chloride, and a nonionic surfactant. A constant potential is applied to the working electrode, and the metal ion precursors are co-reduced to metal atoms on the electrode surface under the applied potential, thereby depositing on the electrode surface. The electrode is then electrochemically dealloyed with the platinum-cobalt alloy in an HClO₄ solution, causing most of the cobalt to dissolve or migrate into the material, forming a platinum-rich surface. Subsequently, the residual surfactant in the material is removed with ethanol, and the electrode is rinsed clean before use.

[0010] Preferably, the working electrode is a glassy carbon electrode or a platinum electrode.

[0011] Preferably, the electrolyte is prepared as follows: dissolving the triblock copolymer surfactant in a mixture of tetrahydrofuran (THF) and ethanol, then mixing the mixture with potassium chloroplatinite and cobalt chloride solution. The electrolyte is stored at 4° C. in the dark.

[0012] Preferably, the molar ratio of platinum ions to cobalt ions in the electrolyte is optimized and controlled within the range of 9:11.

[0013] Preferably, the nonionic surfactant is P123.

[0014] Preferably, the dealloying solution is a perchloric acid solution.

[0015] In a second aspect, the present invention provides an electrochemical sensor for direct and real-time detection of NO, which is prepared using the above-mentioned preparation method.

[0016] In a third aspect, the present invention provides the use of the above electrochemical sensor for direct and real-time detection of NO in detecting NO concentration.

[0017] Furthermore, the electrochemical sensor can achieve direct real-time detection of NO in the liquid phase, specifically comprising the following steps: (1) constructing a three-electrode system using a silver / silver chloride electrode as a reference electrode, a platinum wire electrode as a counter electrode, and the prepared electrochemical sensor as a working electrode; (2) placing the three-electrode system in a 0.1 mol / L phosphate buffer solution (pH 7.4); (3) performing pulse voltammetry within a potential range of 0.4 V to 1 V; and (4) adding a sample to the base solution and quantitatively analyzing the NO in the sample using the current peak. If the solution contains NO, an oxidation peak is observed at approximately 0.76 V. If the sample does not contain NO, no oxidation peak is observed, thereby enabling qualitative analysis of NO. Furthermore, the magnitude of the current peak is proportional to the concentration of NO in the solution, thus enabling quantitative analysis of NO in the sample.

[0018] The electrochemical sensor was applied to the detection of NO using pulse voltammetry, and its linear range was wide, from 1.8nM to 6.1μM and from 6.1μM to 201.5μM. In the low concentration range of 1.8nM to 6.1μM, the sensitivity of the sensor was 173.43μA / μM·cm 2 , the detection limit was 1.74±0.026nM.

[0019] The beneficial effects of the present invention are:

[0020] (1) The present invention provides a method for preparing platinum-cobalt bimetallic nanomaterials based on electrochemical dealloying technology. The method first places an electrode in an electrolyte containing a surfactant, and co-deposits platinum and cobalt metal atoms on the electrode surface by electrodeposition; then, electrochemical dealloying technology is used to selectively dissolve most of the cobalt or migrate into the interior of the material, forming a platinum-rich surface structure, thereby significantly improving the catalytic performance of the material. As an effective electrochemical activation method, electrochemical dealloying can achieve performance control of nanomaterials and construct a material interface with excellent catalytic activity.

[0021] (2) This invention is the first to apply a platinum-cobalt bimetallic nanomaterial prepared by electrochemical dealloying to the construction of a nitric oxide electrochemical sensor. Experiments show that the material exhibits excellent sensitivity to low concentrations of NO, and its oxidation current signal is significantly stronger than that of a bare electrode.

[0022] This enhanced effect stems primarily from two factors: first, the optimized surface properties of the material are controlled by the alloying effect of the platinum-cobalt bimetallic element; second, the highly efficient electrocatalytic activity of the nanoporous platinum-rich surface structure on NO molecules. The resulting sensor exhibits low detection limits and excellent selectivity in practical applications, while also demonstrating excellent electrochemical stability and cycle life, promising promising commercial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0024] Figure 1 CV graphs of the platinum-cobalt bimetallic control material prepared in Example 1 and the porous platinum-cobalt nanomaterial formed by dealloying treatment.

[0025] Figure 2 AB are scanning electron microscope images of the platinum-cobalt bimetallic control material prepared in Examples 1 and 2 and the porous platinum-cobalt nanomaterial formed by dealloying treatment, respectively.

[0026] Figure 3 This is the full X-ray photoelectron spectroscopy (XPS) spectrum of the porous platinum-cobalt nanomaterial formed by dealloying treatment prepared in Example 1.

[0027] Figure 4 AB are the X-ray photoelectron spectroscopy (XPS) narrow spectra of the platinum element in the platinum-cobalt bimetallic reference material and the dealloyed platinum-cobalt nanomaterial prepared in Examples 1 and 2, respectively.

[0028] Figure 5 AB are the electrodes prepared in Example 1 Figure 5 AB are the cyclic voltammograms and differential pulse voltammograms of different electrodes (platinum-cobalt bimetallic reference material modified electrode, dealloyed platinum-cobalt nanomaterial modified electrode) in 10 μM NO, respectively.

[0029] Figure 6 A is the cyclic voltammogram of the porous platinum-cobalt nanomaterial sensor formed by dealloying treatment prepared in Example 1 at different scan rates in 10 μM NO. Figure 6 B is the corresponding linear relationship curve between current and scan rate.

[0030] Figure 7 A is the it curve of the porous platinum-cobalt nanomaterial sensor formed by dealloying treatment prepared in Example 1 in different concentrations of NO (1.8nM-174.5μM), Figure 7 B is the corresponding linear relationship curve.

[0031] Figure 8 This is a graph showing the results of the selectivity test of the sensor constructed in Example 1 for different interfering components.

[0032] Figure 9 This is a graph showing the reproducibility test results of the sensor constructed in Example 1.

[0033] Figure 10 This is a graph showing the stability test results of the sensor constructed in Example 1. DETAILED DESCRIPTION

[0034] The following describes in detail the implementation methods of the present invention through specific examples. Those skilled in the relevant art can clearly understand other advantages and effects of the present invention based on the contents disclosed in this specification. It should be noted that the present invention can also be implemented and applied through other different implementation methods, and the technical details described in this specification can also be appropriately adjusted or changed based on different technical perspectives and application requirements without departing from the core idea of ​​the present invention. All other implementation methods obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work should fall within the scope of protection of the claims of the present invention.

[0035] Example 1

[0036] Construct a nitric oxide electrochemical sensor and prepare it as follows:

[0037] (1) Preparation of metal precursor electrolyte

[0038] Mix the potassium chloroplatinite solution and the cobalt chloride solution until the concentrations of platinum ions and cobalt ions in the electrolyte are 9 μM and 11 μM, respectively (molar ratio 9:11). This mixed solution, the electrolyte, is stored at 4°C in the dark. Deoxygenate the electrolyte by purging with nitrogen for 5 minutes before use.

[0039] (2) Preparation of platinum-cobalt bimetallic modified electrodes by electrochemical deposition

[0040] Using an electrochemical workstation (CHI 660E, CHI Instrument, US), a standard three-electrode system was used, including an Ag / AgCl (saturated KCl) electrode as a reference electrode, a platinum wire as a counter electrode, and a platinum disk electrode or a glassy carbon electrode as a working electrode. At room temperature, the reduction potential of the metal ions was first determined by cyclic voltammetry scanning, and then a constant potential of -0.5 V was applied for electrodeposition. Afterwards, the electrodes were thoroughly rinsed with deionized water and dried in air.

[0041] (3) Assembly of nitric oxide electrochemical sensor

[0042] The modified electrode prepared in step (2) was assembled into a NO electrochemical sensor together with an electrochemical workstation, a counter electrode (platinum wire electrode), a reference electrode (Ag / AgCl electrode), an electrolytic cell and an electrolyte (0.1 mol / L, pH = 7.4 phosphate buffer solution).

[0043] Example 2

[0044] Construct a nitric oxide electrochemical sensor and prepare it as follows:

[0045] (1) Preparation of metal precursor electrolyte

[0046] An amphiphilic surfactant, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123), was dissolved in a mixture of THF and ethanol (volume ratio 1:1) to a mass fraction of 4 wt%. The 4 wt% P123 solution, 20 mM potassium chloroplatinite solution, and 20 mM cobalt chloride solution were mixed to achieve an electrolyte with platinum and cobalt ion concentrations of 9 μM and 11 μM, respectively (molar ratio 9:11), and a P123 mass fraction of 2 wt%. This mixed solution, the electrolyte, was stored at 4°C in the dark. Deoxygenation was performed by purging with nitrogen for 5 minutes before use.

[0047] (2) Preparation of porous platinum-cobalt bimetallic nanomaterials by electrochemical deposition

[0048] Using an electrochemical workstation (CHI 660E, CHI Instrument, US), a standard three-electrode system was used, including an Ag / AgCl (saturated KCl) electrode as a reference electrode, a platinum wire as a counter electrode, and a platinum disk electrode or a glassy carbon electrode as a working electrode. At room temperature, the reduction potential of the metal ions was first determined by cyclic voltammetry scans, and then a constant potential of -0.5 V was applied for electrodeposition, with the reaction time controlled according to the deposited charge (Q).

[0049] (3) Electrochemical dealloying to construct porous platinum-cobalt nanomaterials

[0050] An electrochemical workstation (CHI 660E, CHI Instrument, US) was used with a standard three-electrode system, including an Ag / AgCl (saturated KCl) electrode as a reference electrode, a platinum wire as a counter electrode, and the working electrode as the working electrode. -1 Electrochemical dealloying of a platinum-cobalt alloy was performed in HClO₄ using cyclic voltammetry at a scan rate of 50 mV / s over a potential range of -0.2 V to 1.0 V (vs. Ag / AgCl). Residual surfactant was subsequently removed with ethanol. The electrode was rinsed clean and ready for use.

[0051] (4) Assembly of Nitric Oxide Electrochemical Sensor

[0052] The modified electrode prepared in step (3) was assembled into a NO electrochemical sensor together with an electrochemical workstation, a counter electrode (platinum wire electrode), a reference electrode (Ag / AgCl electrode), an electrolytic cell and an electrolyte (0.1 mol / L, pH = 7.4 phosphate buffer solution).

[0053] Figure 1 This is the CV graph of the porous platinum-cobalt nanomaterial formed by dealloying the platinum-cobalt bimetallic control material prepared in Example 1. Figure 1As can be seen, in the first dealloying cycle (dashed line), an oxidation peak is observed between 0.2V and 1V, attributed to the oxidative dissolution of the Co material. In the tenth dealloying cycle (solid line), the oxidation peak almost disappears, while the characteristic peak in the hydrogen adsorption / desorption region gradually increases, indicating that the material surface is mainly enriched with Pt, with no Co metal present on the surface. This is beneficial for NO electrochemical sensing.

[0054] Figure 2 AB are scanning electron microscope images of the platinum-cobalt bimetallic control material and the porous platinum-cobalt nanomaterial prepared in Examples 1 and 2, respectively. Figure 2 As can be seen from A, the platinum-cobalt bimetallic material presents a non-porous spherical nanostructure, and the electrode surface is covered with smaller spherical nanoparticles that are evenly dispersed. Figure 2 As shown in Figure 2, after dealloying, the electrode surface was significantly modified due to the obvious dissolution of cobalt, and a porous structure was observed.

[0055] Figure 3 The X-ray photoelectron spectrum of the porous platinum-cobalt nanomaterial prepared in Example 2 is as follows: Figure 3 It can be seen that the material shows peaks of Pt 4f (70-76eV) and Co2p (770-790eV), indicating the presence of these two metal atoms.

[0056] Figure 4 AB are the X-ray photoelectron spectrum narrow spectra of platinum element in the platinum-cobalt bimetallic material and porous platinum-cobalt nanomaterial prepared in Examples 1 and 2, respectively. Figure 4 A shows that there are zero-valent and divalent platinum in the Pt 4f region of the Pt-Co bimetallic without P123 addition and dealloying treatment. 0 The peaks of appear at 73.9eV and 70.3eV. Figure 3 B shows that the divalent platinum in the prepared porous platinum-cobalt nanomaterial is reduced, and the main presence is zero-valent platinum. 0 The two peaks shifted to 74.0eV and 70.43eV respectively, shifting in the positive direction, indicating that the Pt-rich surface was electronically modified after dealloying.

[0057] Table 1 shows the elemental content of the platinum-cobalt bimetallic material and the porous platinum-cobalt nanomaterial prepared in Examples 1 and 2. The surface elemental composition was obtained by X-ray photoelectron spectroscopy, and the overall elemental composition was obtained by inductively coupled plasma emission spectroscopy. As can be seen from Table 1, in the platinum-cobalt bimetallic material, the platinum:cobalt ratio in the overall structure is 1:0.25, which does not conform to the ratio in the metal precursor (1:1.22); the surface platinum:cobalt ratio is 1:0.13, indicating that most of the silver and copper are enriched on the surface at this time. In the porous platinum-silver-copper core-shell nanomaterial, the platinum:cobalt ratio in the overall structure is 1:0.38; the surface platinum:cobalt ratio is 1:0.23, indicating that dealloying dissolves most of the cobalt, and the remaining cobalt migrates to the interior of the material to form a platinum-rich surface.

[0058] Figure 5 AB are the cyclic voltammograms and differential pulse voltammograms of the electrodes prepared in Examples 1 and 2 and the bare platinum electrode in 10 μM NO, respectively. Figure 5 It can be seen that the porous platinum-cobalt nanostructured NO sensor has the highest oxidation current and the lowest oxidation potential, showing high electrochemical sensing performance for NO.

[0059] Figure 6 A is the cyclic voltammogram of the sensor prepared in Example 2 at different scan rates in 10 μM NO, Figure 6 B is the linear relationship curve between the corresponding current and the scan rate. Figure 6 B shows that there is a linear relationship between the anode peak current and the scan rate (R 2 =0.997), which indicates that the kinetic process of NO on the surface of porous Pt-Co nanostructures is mainly controlled by adsorption.

[0060] Example 3

[0061] The sensor prepared in Example 2 was used to test the chronoamperometric current response in different concentrations of NO (1.8 nM-174.5 μM). The results are as follows: Figure 7 As shown in A. Figure 7 It can be seen that at the potential of +0.8V, as the NO concentration gradually increases, the current response gradually increases. The oxidation current and NO concentration show a good linear relationship in the two ranges ( Figure 7 B): 1.8nM~4.0μM, 2.6μM~174.5μM. The sensor is more sensitive to low concentration NO, and I(μA)=143.427C NO +10.492(R 2 =0.998), the sensitivity was calculated to be 173.43 μA / μM·cm and the detection limit was 1.74±0.026 nM. This indicates that the improved sensing interface has high sensitivity and low detection limit, making it suitable for trace NO detection.

[0062] Example 4

[0063] Solutions of different substances were sequentially added to the electrolyte of the sensor constructed in Example 2 to test the sensor's chronoamperometric response to different interfering components. The test voltage was 0.8 V, and the time interval between adding different interfering substances was 60 seconds. The amperometric response curves of the sensor's selectivity test for different interfering components were obtained. The results are shown in Figure 2. Figure 8 As shown. Figure 8 It can be seen that the sensor has good selectivity for NO.

[0064] Example 5

[0065] The differential pulse voltammetric responses of the sensors of 5 different batches constructed in Example 2 were tested in 10 μM NO with an applied voltage of 0.8 V. The results are shown in FIG. Figure 9 As shown. Figure 9 It can be seen that the sensor has good test reproducibility.

[0066] Example 6

[0067] The differential pulse voltammetric response of the sensor constructed in Example 2 in 10 μM NO after 0, 2, 4, 6, 8, and 10 days was tested. The results are shown in FIG. Figure 10 As shown. Figure 10 It can be seen that the sensor has good test stability.

[0068] Table 1 shows the inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray photoelectron spectroscopy (XPS) results of the platinum-cobalt bimetallic control materials prepared in Examples 1 and 2 and the porous platinum-cobalt nanomaterials formed by dealloying treatment, showing the content of each element of platinum and cobalt.

[0069] It should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail through preferred embodiments, those skilled in the art should understand that appropriate modifications or equivalent substitutions may be made to the technical solutions without departing from the core concept and scope of protection of the present invention, and such modifications or substitutions should be included within the scope of the claims of the present invention.

Claims

1. A method for preparing an electrochemical NO sensor based on electrochemical dealloyed platinum-cobalt bimetallic nanomaterials, characterized in that: The nitric oxide electrochemical sensor includes an electrochemical workstation, a working electrode with a surface modified with electrochemically dealloyed platinum-cobalt bimetallic nanomaterials, a counter electrode, a reference electrode, an electrolytic cell, and an electrolyte. The preparation method of the working electrode whose surface is modified with electrochemically dealloyed platinum-cobalt bimetallic nanomaterials is as follows: first, immersing the electrode in an electrolyte containing platinum salt, cobalt salt metal ion precursor and non-ionic surfactant P123, and performing electrodeposition at a constant potential of -0.5V; driven by an external potential, the metal ions are gradually reduced to metal atoms on the electrode surface, and the reaction time is controlled by the amount of deposited charge Q; then, electrochemically dealloying the platinum-cobalt alloy is performed by cyclic voltammetry in a nitrogen-saturated HClO4 solution; wherein the scan rate is 50mV / s and the potential range is -0.2V to 1.0V vs.Ag / AgCl; the process selectively oxidizes and dissolves the cobalt atoms on the outer surface, while inducing the remaining cobalt atoms to migrate inward to form a platinum-rich core-shell structure; the degree of dealloying is determined by monitoring the change of the cobalt oxidation peak in the cyclic voltammogram, and when the cobalt oxidation peak is no longer observed, the dealloying is complete; finally, the residual surfactant is removed with ethanol, and the finished electrode is obtained after rinsing; The electrolyte was prepared as follows: first, the amphiphilic surfactant polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer P123 was dissolved in a mixed solvent of tetrahydrofuran and ethanol with a volume ratio of 1:1; then the P123 solution was mixed with a K2PtCl4 solution and a CoCl2 solution to prepare an electrolyte containing 2 wt% P123, and Pt 2+ and Co 2+ The concentrations of α and β were 9 μM and 11 μM respectively; the prepared electrolyte solution should be stored at 4°C in the dark; The working electrode is a glassy carbon electrode or a platinum electrode.

2. The method according to claim 1, wherein The platinum salt is potassium chloroplatinite, and the cobalt salt is cobalt chloride.

3. The method according to claim 1, wherein The electrolyte used in the electrochemical dealloying process is 0.1 mol·L -1 HClO4, the electrochemical technique used is cyclic voltammetry (CV); the number of CV cycles varies in the range of 5-50 cycles, and the degree of dealloying is judged by observing the cobalt characteristic peak. When the cobalt oxidation peak is no longer observed in the CV graph, the dealloying is complete.

4. The NO electrochemical sensor obtained by the preparation method according to any one of claims 1 to 3.

5. The use of the NO electrochemical sensor according to claim 4, characterized in that: The electrochemical sensor is applied to the detection of NO in liquid phase.

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