Functionalized gold-silver nanalloy wire composite photoelectric material, and preparation method and application thereof

Abstract

The application discloses a functionalized gold-silver nanowire alloy composite photoelectric material and a preparation method and application thereof. A pillar[6]arene molecule AuAg@WP6 capable of undergoing host-guest complexation with a serotonin molecule 5- HT is wrapped on the surface of gold-silver nanowire alloy AuAg NWs, and the AuAg@WP6 / rGO-C3N4 is loaded on a reduced graphene oxide and carbon nitride rGO-C3N4 composite material to design a PEC biosensing system. The AuAg@WP6 / rGO-C3N4 serves as a sensing material. The LSPR effect of the AuAg NWs under visible light irradiation promotes charge separation. The host-guest complexation of the WP6 can selectively adsorb a large amount of 5- HT to the surface of the material. Since the g-C3N4 and the rGO have similar pi-conjugated structures, the two are easy to be bonded to form the rGO-C3N4 composite material. The photo-induced holes on the rGO-C3N4 can accelerate the oxidation of the serotonin molecule, and further improve the photocurrent response to detect 5- HT. Based on the excellent photoelectrochemical performance of the composite material, the linear range for detecting 5- HT is 0.01-100 muM, and the detection limit is 2 nM (S / N=3).

Description

Technical Field

[0001] The present invention belongs to the field of photoelectrochemical technology, and specifically relates to a functionalized gold-silver nano-alloy wire composite photoelectric material, a preparation method, and an application thereof. Background Art

[0002] Serotonin, also known as 5-hydroxytryptamine (5-HT), is a crucial neurotransmitter that acts on the central nervous system and some peripheral organs. It plays a role in regulating anxiety, mood, appetite, and even sleep. Fluctuations in its levels are closely associated with a variety of neurological and peripheral organ diseases, including anxiety, depression, Parkinson's disease, insomnia, gastrointestinal disorders, and heart disease. 5-HT has complex connections with endocrine disorders, diabetes, and even cancer, and can serve as an important biomarker for several diseases.

[0003] The content of 5-HT in normal human urine is about 300-1650nM. Similarly, the content of 5-HT in blood is about 262-1550nM 5-HT. Commonly used 5-HT detection methods include high performance liquid chromatography, enzyme-linked immunosorbent assay and electrochemical method. These methods require specific enzymes or special strategies to improve the selectivity of the determination method. The complex operation also limits their development. Therefore, there is an urgent need for a 5-HT detection method with high sensitivity, strong selectivity, fast and convenient. Photoelectrochemical (PEC) detection technology is an emerging bioanalysis method developed based on electrochemical detection technology. Due to the separation of excitation signal and detection signal (electricity), this detection method has a lower background signal, thereby obtaining a higher signal-to-noise ratio, and therefore has ultra-high sensitivity.

[0004] Using precious metal nanoparticles with a unique LSPR effect to modify electrode materials is currently an effective way to enhance the PEC performance of materials. By integrating the LSPR performance of Au and the good conductivity of Ag, a layer of Au was plated on the surface of previously synthesized silver nanowires (Ag NWs) through an ion exchange method, successfully synthesizing a gold-silver nanowire (AuAg NWs) composite material. This material not only has good photoelectrochemical properties but also excellent charge transfer capabilities. In PEC sensing, good specific recognition capabilities are indispensable. Traditional sensors based on Au or Ag are often limited by their lack of specific recognition capabilities. Therefore, it is necessary to add a sensing strategy that specifically recognizes 5-HT to PEC sensing. The unique size-adjustable cavity structure, host-guest complexation ability, and highly adjustable functionalized edges of water-soluble columnar aromatics provide a new method for specifically recognizing target substances to construct specific sensors. In addition, pillar[n]arenes with groups such as amine (-NH2) or carboxyl (-COOH) groups can be easily functionalized with Au or other inorganic nanomaterials, and the above groups can be designed to be specific groups that bind to target species.

[0005] Reduced graphene oxide (rGO) is a good adsorption material and electrochemically active material with the characteristics of large surface area, high electrical conductivity, strong adsorption capacity and good visible light absorption capacity. Therefore, rGO with a large surface area can load AuAg NWs and promote charge transfer. Graphitic carbon nitride (g-C3N4) is widely used in the field of photoelectrochemistry because of its strong light absorption capacity, excellent stability and easy synthesis. However, due to the small specific surface area of ​​g-C3N4 and the problem of easy recombination of photogenerated carriers, its widespread use is limited. Therefore, it is necessary to modify it with suitable materials to avoid these problems. Summary of the Invention

[0006] Technical issues solved:

[0007] This application addresses the technical problems of the existing technology, such as low sensitivity, limited detection range, expensive instruments, etc., and provides a functionalized gold-silver nano-alloy wire composite optoelectronic material and its preparation method and application.

[0008] Technical solution:

[0009] To achieve the above objectives, this application is implemented through the following technical solutions:

[0010] The preparation method of functionalized gold-silver nano-alloy wire composite photoelectric material specifically comprises the following steps:

[0011] Step 1: Preparation of anionic water-soluble [2]biphenyl extended column [6]arene WP6;

[0012] The second step is to prepare a silver nanowire solution: 85-90g of polyvinyl pyrrolidone with a molecular weight of 58,000 is dissolved in 5-15mL of 1,2-propylene glycol and transferred to a 25mL flask. The solution is heated in an oil bath at 150-170°C and stirred continuously at 450rpm for 1-2 hours. 1-2mL of sodium chloride dissolved in 1,2-propylene glycol is quickly added to a concentration of 1mM. After stirring at 450rpm for 5-10 minutes, 3-5mL of 0.15M silver nitrate 1,2-propylene glycol solution is added dropwise using a syringe pump. The solution is then heated at 450rpm and stirred for 30-60 minutes to obtain a silvery-white AgNWs crude solution. The centrifuge speed is controlled at 6500-7500rpm. The crude Ag NWs solution is centrifuged and washed with ultrapure water to obtain pure Ag nanowires. The pure Ag NWs are dispersed in 20-25mL of ultrapure water for subsequent storage and use.

[0013] Step 3: Prepare gold-silver nanowire solution: add 2-3 mL of 20 mM sodium hydroxide aqueous solution, 100-120 μL of 25.4 mM chloroauric acid aqueous solution and 17-19 mL of ultrapure water into the reaction kettle, and stir at 500 rpm for 1-2 hours at room temperature to obtain mixed solution A; add 40-50 mg of PVP to 3-5 mL of ultrapure water and heat at 60 ° C to obtain solution B; after 2 minutes, add 500-600 μL of 100 mM anti- Ascorbic acid AA and 500-600 μL of 200 mM sodium hydroxide were added to solution B. After stirring at 500 rpm for 5 minutes, 700-800 μL of the AgNWs solution prepared in the second step was added to solution B to obtain a mixed solution C. After rapid stirring at 800 rpm for 10 minutes, the mixed solution A was dripped dropwise into the mixed solution C at a rate of one drop per 3 seconds. After the dripping was completed, the mixture was heated and stirred at 800 rpm for 10-20 minutes, and then the reaction was stopped to obtain a crude AuAg NWs solution. The crude AuAg NWs solution was centrifuged and washed with ultrapure water at 6500-7500 rpm to obtain pure AuAg NWs. The product was dispersed in 7-8 mL of ultrapure water for subsequent use.

[0014] The fourth step is to prepare AuAg@WP6 NWs by ultrasonic method: take 0.1-0.2 mL of AuAg NWs synthesized in the third step, add 0.8-1 mL of ultrapure water, add 1-1.5 mg of WP6 and ultrasonicate for 1-2 hours to prepare AuAg@WP6 NWs;

[0015] The fifth step is to prepare reduced graphene oxide by graphene oxide: 10-20 mg of graphene oxide GO and 10-15 mL of ultrapure water are added to a flask and dispersed by ultrasonication for 1-2 hours to obtain a GO dispersion. The GO dispersion is added to a reactor and 45-50 mL of ethanol is added. The pH of the mixed solution is adjusted with a 1 M potassium hydroxide aqueous solution and the pH value is detected with a pH test paper. When the pH of the dispersion reaches 9.0-10.0, the reactor is placed in an oven and heated at 80-85 ° C for two hours to obtain a product rGO precipitate. The black precipitate is ultrasonically dispersed and centrifuged and washed with deionized water to obtain a pure rGO dispersion, which is dispersed in 20-25 mL of ultrapure water to obtain 0.6 mg mL -1 rGO dispersion;

[0016] Step 6: Prepare reduced graphene oxide-carbon nitride rGO-C3N4 by compounding graphene-like π-conjugated structure with graphene: 5 mg of graphene-carbon nitride g-C3N4 was dissolved in 2 mL of isopropanol and stirred at 450 rpm to obtain 2.5 mg mL -1g-C3N4 suspension; 0.03mL g-C3N4 suspension and 0.5mL rGO dispersion were mixed thoroughly at 450rpm to obtain rGO-C3N4 composite suspension;

[0017] In the seventh step, 10 μL of the rGO-C3N4 solution prepared in the sixth step was dropped on the surface of the glassy carbon electrode polished smooth with alumina and dried at 50°C. Then, 10 μL of the AuAg@WP6 NWs solution prepared in the fourth step was dropped on the electrode surface and dried at 50°C to obtain the AuAg@WP6 / rGO-C3N4 composite photoelectric material for subsequent use.

[0018] Furthermore, the second step of preparing the silver nanowire solution is specifically as follows:

[0019] S1. Dissolve 87 g of polyvinylpyrrolidone (MW 58,000) in 10 mL of 1,2-propylene glycol and transfer the mixture to a 25 mL flask. Heat the mixture in an oil bath at 160 °C and stir continuously at 450 rpm for 1 hour.

[0020] S2. Quickly add 1 mL of sodium chloride dissolved in 1,2-propylene glycol to a concentration of 1 mM. After stirring at 450 rpm for 5 minutes, add 4 mL of 0.15 M silver nitrate 1,2-propylene glycol solution dropwise using a syringe pump. Then heat and stir at 450 rpm for 40 minutes to obtain a silvery-white Ag NWs crude solution.

[0021] S3, controlling the centrifuge speed to 7000 rpm, using a centrifuge and ultrapure water to centrifuge and wash the crude Ag NWs solution to obtain pure Ag nanowires;

[0022] S4. Use 20 mL of ultrapure water to disperse the purified Ag NWs for subsequent storage and use.

[0023] Furthermore, the third step of preparing the gold-silver nanowire solution by the ion exchange method specifically includes the following steps:

[0024] Step 1: Add 2 mL of 20 mM sodium hydroxide aqueous solution, 100 μL of 25.4 mM chloroauric acid aqueous solution, and 17.9 mL of ultrapure water into a reaction vessel, and stir at 500 rpm for 1 hour at room temperature to obtain a mixed solution A;

[0025] Step 2: Add 40 mg of PVP to 3 mL of ultrapure water and heat at 60°C to obtain solution B;

[0026] Step 3: After 2 minutes, 500 μL of 100 mM ascorbic acid AA and 500 μL of 200 mM sodium hydroxide were added to solution B. After stirring at 500 rpm for 5 minutes, 700 μL of the AgNWs solution prepared in the second step was added to solution B to obtain a mixed solution C. After rapid stirring at 800 rpm for 10 minutes, mixed solution A was dripped dropwise into mixed solution C at a rate of one drop per 3 seconds. After the dripping was completed, heating was continued at 800 rpm and stirring was continued for 10 minutes before stopping the reaction to obtain a crude AuAg NWs solution.

[0027] Step 4: The crude AuAg NWs solution was centrifuged and washed several times with ultrapure water at 7000 rpm to obtain pure AuAgNWs, and the product was dispersed in 7 mL of ultrapure water for subsequent use.

[0028] Furthermore, in the first step, anionic water-soluble [2]biphenyl extended column [6]arene WP6 is prepared, and the process route is as follows:

[0029] Furthermore, in the fourth step, 0.14 mL of the AuAgNWs synthesized in the third step was taken, 0.86 mL of ultrapure water was added, and 1.26 mg of WP6 was added and ultrasonicated for 1.5 hours to prepare AuAg@WP6 NWs.

[0030] Furthermore, the fifth step of preparing reduced graphene oxide by graphene oxide is specifically as follows:

[0031] Step a: 14 mg of graphene oxide (GO) and 10 mL of ultrapure water were added to a flask and dispersed by ultrasonication for 2 h to obtain a GO dispersion.

[0032] Step b: The GO dispersion was added to a reactor, and 46 mL of ethanol was added. The pH of the mixed solution was adjusted with a 1 M potassium hydroxide aqueous solution and tested with pH test paper. When the pH of the dispersion reached 9.0-10.0, the reactor was placed in an oven and heated at 80°C for two hours to obtain the product rGO precipitate.

[0033] Step c: Ultrasonic dispersion of black precipitate was performed and washed with centrifugal and deionized water to obtain pure rGO dispersion, which was then dispersed in 23 mL of ultrapure water to obtain 0.6 mg mL -1 rGO dispersion.

[0034] A functionalized gold-silver nano alloy wire composite photoelectric material prepared by any of the above preparation methods.

[0035] This application also discloses the application of functionalized gold-silver nano alloy wire composite photoelectric material in a novel signal switch type photoelectrochemical PEC sensing system. 2 10 μL rGO-C3N4 composite photoelectric material solution was drop-coated on the glassy carbon electrode and dried at 50 °C. Then, 10 μL AuAg@WP6 NWs composite photoelectric material solution was drop-coated on the electrode surface and dried at 50 °C to prepare AuAg@WP6 / rGO-C3N4 / GCE nanocomposite electrode.

[0036] Furthermore, the novel signal switch type photoelectrochemical PEC sensing system uses a traditional three-electrode system to

[0037] The AuAg@WP6 / rGO-C3N4 / GCE nanocomposite electrode was used as the working electrode, the platinum mesh was used as the counter electrode, and the saturated calomel electrode (SCE) was used as the reference electrode. A xenon lamp was used to simulate a visible light source to illuminate the AuAg@WP6 / rGO-C3N4 / GCE surface, and the shading interval time was controlled as an adjustable "on-off" switch. The electrochemical workstation was then used for photoelectrochemical detection in a phosphate buffer solution containing serotonin.

[0038] Principle explanation: Through the ion exchange method, a layer of Au was plated on the surface of Ag NWs to successfully synthesize the gold-silver alloy nanowire AuAg NWs composite material, and the AuAg NWs were functionalized with extended column [6] aromatic hydrocarbons to prepare AuAg@WP6. Then, reduced graphene oxide was prepared by graphene oxide, and the two were compounded through the similar π-conjugated structure of graphite phase carbon nitride and graphene to prepare reduced graphene oxide-carbon nitride (rGO-C3N4). Finally, rGO-C3N4 with a large surface area was used to load

[0039] AuAg@WP6, preparation of AuAg@WP6 / rGO-C3N4 composite photoelectric materials.

[0040] Beneficial effects:

[0041] This application provides a functionalized gold-silver nano-alloy wire composite optoelectronic material and its preparation method and application, which has the following beneficial effects compared with the existing technology:

[0042] 1. This application designs AuAg alloy nanowires that form localized surface plasmon resonance effects under visible light, as well as extended macrocyclic pillar[6]arene WP6 with stronger host-guest complexing ability, and reduced graphene oxide-carbon nitride composite materials with large specific surface area, redox properties, and strong light absorption capacity, which can be used for photoelectrochemical detection of serotonin (5-HT);

[0043] 2. This application solves the technical problems of the existing detection technology, such as low sensitivity, limited detection range, serious environmental pollution, expensive instruments, need for specialized operators, low efficiency, slow speed, and difficulty in operation;

[0044] 3. The detection range of the functionalized gold-silver nano-alloy wire composite photoelectric material of this application is 0.01-100 μmol / L, and the sensitivity is 0.7640 μAcm -2 μmol / L -1 , the detection limit was 2nmol / L(S / N);

[0045] 4. The expanded macrocyclic column [6] square hydrocarbon synthesized in this application has a good host-guest complexation with serotonin molecules, and the host-guest complexation constant is 13721;

[0046] 5. The detection of serotonin molecules in this application has good stability and reproducibility, with a relative standard deviation of 2.8% measured in five parallel experiments;

[0047] 6. The anionic water-soluble [2] biphenyl extended pillar [6] aromatic hydrocarbon modified by 8 ammonium salt ions used in this application, referred to as extended macrocyclic WP6, has a larger cavity volume than traditional pillar [5] and pillar [6] aromatic hydrocarbons, and can ionize in water to release NH4 + ions, thus carrying a negative charge, and expanding the macrocyclic WP6 molecular structure similar to a root tube, with 4 -COONH4 groups on each side. After dissolving in water, the -COONH4 groups on both sides will form free NH4 + cation, leaving behind a negatively charged -COO - , electrostatic attraction occurs with the positively charged 5-HT molecule, enters its cavity, and a host-guest complexation reaction occurs. Compared with the traditional WP5 and WP6, the synthesized expanded macrocyclic WP6 has a larger cavity volume, so the host-guest complexation ability is stronger. In addition, -COO - The strong interaction between WP6 and AuAgNWs can combine to prepare AuAg@WP6 NWs, so that the composite material can selectively recognize 5-HT while having excellent photoelectrochemical properties. However, AuAg NWs are large in size and require a material with a large surface area as a substrate to load AuAg NWs; g-C3N4 and graphene have similar π-conjugated structures, which makes the two easy to bond. By using a suitable method to composite the two materials with rGO-C3N4, it is bound to be able to improve the photoelectrochemical performance of the composite material while solving the problems of small specific surface area and high carrier recombination rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1The figures are SEM images of this application, where A is the SEM image of AgNWs; B is the SEM image of AuAg NWs; C is the SEM image of rGO-C3N4; D is the SEM image of AuAg@WP6 / rGO-C3N4;

[0049] Figure 2 The XRD powder diffraction pattern and visible absorption spectrum of the present application, wherein A is the XRD powder diffraction pattern of rGO-C3N4, AuAg@WP6, and AuAg@WP6 / rGO-C3N4, and B is the UV absorption spectrum of Ag, AuAg, WP6, and AuAg@WP6;

[0050] Figure 3 : The time current (IT) curve and Nyquist (EIS) diagram of the present application under visible light irradiation, wherein a is Ag / GCE, b is AuAg / GCE, c is AuAg@WP6 / GCE, and d is the time current (IT) curve of AuAg@WP6 / rGO-C3N4 / GCE in 20 mL 0.1 M phosphate buffer solution (pH = 7.0) containing 0.02 mM 5-HT under visible light irradiation as shown in Figure A; the Nyquist (EIS) diagram of Ag / GCE (a), AuAg / GCE (b), AuAg@WP6 / GCE (c), and AuAg@WP6 / rGO-C3N4 / GCE (d) in a mixed solution of 5 mM K3[Fe(CN)6] / K4[Fe(CN)6] and 0.1 M KCl is shown in Figure B;

[0051] Figure 4 The differential pulse voltammetry curve (A) and the linear fitting curve of the oxidation peak current (B) of the sensor of the present application for 0.01-100 μmol / L 5-HT;

[0052] Figure 5 This is a flow chart of the synthetic method for expanding the macrocyclic column [6] aromatic hydrocarbon WP6 in this application. DETAILED DESCRIPTION

[0053] The present invention is further described below with reference to examples. The examples are only used to illustrate the present invention and do not limit the scope of the claims. Other alternative means that can be thought of by those skilled in the art are all within the scope of the claims of the present invention.

[0054] Example 1:

[0055] The preparation method of functionalized gold-silver nano-alloy wire composite photoelectric material specifically comprises the following steps:

[0056] The first step is to prepare anionic water-soluble [2]biphenyl extended column [6]arene WP6:

[0057]

[0058] The second step is to prepare a silver nanowire solution: 87g of polyvinyl pyrrolidone with a molecular weight of 58,000 is dissolved in 10mL of 1,2-propylene glycol and transferred to a 25mL flask. It is heated in an oil bath at 160°C and stirred continuously at 450rpm for 1 hour. 1mL of sodium chloride dissolved in 1,2-propylene glycol is quickly added to a concentration of 1mM. After stirring at 450rpm for 5 minutes, 4mL of 0.15M silver nitrate 1,2-propylene glycol solution is added dropwise using a syringe pump. Then, the mixture is heated and stirred at 450rpm for 40 minutes to obtain a silvery-white AgNWs crude solution. The centrifuge speed is controlled at 7000rpm. The Ag NWs crude solution is centrifuged and washed with ultrapure water to obtain pure Ag nanowires. The pure Ag NWs are dispersed in 20mL of ultrapure water for subsequent storage and use.

[0059] Step 3: Preparation of gold and silver nanowire solution: 2 mL of 20 mM sodium hydroxide aqueous solution, 100 μL of 25.4 mM chloroauric acid aqueous solution and 17.9 mL of ultrapure water were added to the reactor and stirred at 500 rpm for 1 hour to obtain a mixed solution A; 40 mg of PVP was added to 3 mL of ultrapure water and heated at 60 ° C to obtain a solution B; 2 minutes later, 500 μL of 100 mM ascorbic acid AA and 500 μL of 200 mM sodium hydroxide were added to the B solution, stirred at 500 rpm for 5 minutes, and then 700 μL of the AgNWs solution prepared in the second step was added to the B solution to obtain a mixed solution C; after rapid stirring at 800 rpm for 10 minutes, the mixed solution A was dripped dropwise into the mixed solution C at a speed of one drop per 3 seconds, and continued to heat and stir at 800 rpm for 10 minutes after the dripping was completed to stop the reaction to obtain a crude AuAg NWs solution, which was centrifuged and washed with ultrapure water at 7000 rpm. The crude NWs solution was used to obtain pure AuAgNWs, which were then dispersed in 7 mL of ultrapure water for subsequent use.

[0060] The fourth step was to prepare AuAg@WP6 NWs by ultrasonic method: 0.14 mL of AuAg NWs synthesized in the third step was added to 0.86 mL of ultrapure water and 1.26 mg of WP6 and ultrasonicated for 1.5 h to prepare AuAg@WP6 NWs;

[0061] The fifth step is to prepare reduced graphene oxide by graphene oxide: 14 mg of graphene oxide GO and 10 mL of ultrapure water are added to a flask and dispersed by ultrasonication for 2 hours to obtain a GO dispersion. The GO dispersion is added to a reactor and 46 mL of ethanol is added. The pH of the mixed solution is adjusted with a 1 M potassium hydroxide aqueous solution and the pH value is detected with a pH test paper. When the pH of the dispersion reaches 9.0-10.0, the reactor is placed in an oven and heated at 80 ° C for two hours to obtain a product rGO precipitate. The black precipitate is ultrasonically dispersed and centrifuged and washed with deionized water to obtain a pure rGO dispersion, which is dispersed in 23 mL of ultrapure water to obtain 0.6 mg mL -1 rGO dispersion;

[0062] Step 6: Prepare reduced graphene oxide-carbon nitride rGO-C3N4 by compounding graphene-like π-conjugated structure with graphene: 5 mg of graphene-carbon nitride g-C3N4 was dissolved in 2 mL of isopropanol and stirred at 450 rpm to obtain 2.5 mg mL -1 g-C3N4 suspension; 0.03mL g-C3N4 suspension and 0.5mL rGO dispersion were mixed thoroughly at 450rpm to obtain rGO-C3N4 composite suspension;

[0063] In the seventh step, 10 μL of the rGO-C3N4 solution prepared in the sixth step was dropped on the surface of the glassy carbon electrode polished with alumina and dried at 50°C. Then, 10 μL of the AuAg@WP6 NWs solution prepared in the fourth step was dropped on the electrode surface and dried at 50°C.

[0064] After drying, the AuAg@WP6 / rGO-C3N4 composite photoelectric material was obtained for subsequent use.

[0065] Example 2

[0066] The composite photoelectric material AuAg@WP6 / rGO-C3N4 prepared in Example 1 was used in a novel signal-switching photoelectrochemical (PEC) sensing system. The electrodes were placed in a phosphate buffer solution containing serotonin for photoelectrochemical detection of 5-HT. The novel signal-switching PEC sensing system employed a conventional three-electrode system, with the AuAg@WP6 / rGO-C3N4 electrode as the working electrode, a platinum metal mesh electrode as the counter electrode, and a saturated calomel electrode (SCE) as the reference electrode. Photoelectrochemical detection was performed using an electrochemical workstation, with a xenon lamp serving as the analog power source.

[0067] Performance Testing

[0068] 1. Morphological determination of Ag, AuAg, rGO-C3N4 and AuAg@WP6 / rGO-C3N4

[0069] like Figure 1 A is a typical Ag nanowire image shown in Figure 1. The prepared Ag NWs have uniform size and complete morphology. Figure 1 In Figure B, it can be seen that the surface of AuAg NWs prepared by ion exchange method is smooth. Figure 1 As shown in Figure C, rGO-C3N4 nanosheets are composed of many layered structures and have a large surface area, so they have enough area to load AuAg@WP6NWs. In addition, Figure 1 As shown in Figure D, AuAg@WP6 is evenly dispersed in rGO-C3N4 to form AuAg@WP6 / rGO-C3N4 composite materials.

[0070] 2. XRD powder diffraction and UV characterization of AuAg@WP6 / rGO-C3N4 composite photoelectric materials

[0071] Figure 2 Figure A is the XRD powder diffraction pattern of rGO-C3N4, AuAg@WP6 NWs, and AuAg@WP6 / rGO-C3N4. It can be seen from the figure that AuAg@WP6 / rGO-C3N4 clearly shows the (111), (200), (220), (311) crystal planes of typical AuAg NWs, the (002) crystal plane of rGO, and the (100) and (002) crystal planes of g-C3N4. In addition, the peak at 21.59° is the amorphous diffraction peak of WP6, indicating the successful synthesis of the AuAg@WP6 / rGO-C3N4 composite optoelectronic material.

[0072] Figure 2 Figure B is the UV-visible absorption spectra of Ag, AuAg, WP6 and AuAg@WP6 NWs. Among them, the absorption peaks of Ag and WP6 are located at 370nm and 260nm, respectively, which is consistent with previous reports. After a layer of Au is replaced on the surface of Ag NWs, its UV absorption peak at 370nm red-shifts, which may be the effect of Au doping, and the composite material also has an absorption peak at 521nm, which is the plasma resonance absorption peak of gold. In the UV absorption spectrum of AuAg@WP6 NWs, there are obvious absorption peaks at these positions, indicating that the materials are successfully combined. In addition, the monomer absorption peak of the composite material is weaker than that of the individual material. This is mainly because the strong absorption peak of WP6 near 260nm may affect other broad absorption peaks.

[0073] 3. Electrochemical Characterization

[0074] like Figure 3As shown in Figure A, the photoelectrochemical activity of Ag / GCE, AuAg / GCE, AuAg@WP6 / GCE, and AuAg@WP6 / rGO-C3N4 / GCE in 20 mL of 0.1 M phosphate buffer solution (pH = 7.0) containing 0.02 mM 5-HT under visible light irradiation is investigated using time-current (it) curves in phosphate buffer solution containing 0.02 mM serotonin. Under light illumination, the photocurrent density of AuAg@WP6 / rGO-C3N4 / GCE increases dramatically, while in the dark, it decreases rapidly. Compared to Ag / GCE and AuAg@WP6 / GCE, AuAg@WP6 / rGO-C3N4 / GCE exhibits the highest photocurrent density, primarily due to the synergistic effect between AuAg@WP6 and rGO-C3N4.

[0075] like Figure 3 As shown in Figure B, Nyquist electron microscope (EIS) patterns were measured in a solution containing 5.0 mM K3[Fe(CN)6] / K4[Fe(CN)6] and 0.1 M KCl. The diameter of the semicircle can be used to assess the charge transfer resistance (Rct) of the electrode; a larger diameter indicates a higher charge transfer resistance. The figure shows that the electron transfer capacity increases in the order: Ag / GCE > AuAg / GCE > AuAg@WP6 / GCE > AuAg@WP6 / rGO-C3N4 / GCE, demonstrating the composite's high charge transfer capacity.

[0076] 4. Detection of serotonin

[0077] like Figure 4 As shown, the concentration of serotonin can be detected by monitoring the photocurrent intensity of the PEC sensor. The photocurrent response of the sensor is directly related to the concentration of serotonin. Figure 4 A in the middle shows that the photocurrent increases with the increase of serotonin concentration. Figure 4 Middle B shows that the photocurrent response increases linearly with increasing serotonin concentration in the range of 0.01 μmol / L to 100 μmol / L. The calibration equation is I = 0.7640C 5-HT +3.2953, with a correlation coefficient of 0.9957. The oxidation peak current density gradually increased with increasing serotonin concentration. The photoelectrochemical sensor showed a better detection limit of 2 nmol / L, indicating that the proposed sensor may meet the requirements for future improvements in serotonin analysis.

[0078] Example 3:

[0079] The preparation method of functionalized gold-silver nano-alloy wire composite photoelectric material AuAg@WP6 / rGO-C3N4 specifically comprises the following steps:

[0080] The first step is to prepare anionic water-soluble [2]biphenyl extended column [6]arene WP6:

[0081]

[0082] The second step is to prepare a silver nanowire solution: 90g of polyvinyl pyrrolidone with a molecular weight of 58,000 is dissolved in 15mL of 1,2-propylene glycol and transferred to a 25mL flask. It is heated in an oil bath at 170°C and stirred continuously at 450rpm for 2 hours. 2mL of sodium chloride dissolved in 1,2-propylene glycol is quickly added, and the sodium chloride concentration is 1mM. After stirring at 450rpm for 10 minutes, 5mL of 0.15M silver nitrate 1,2-propylene glycol solution is added dropwise using a syringe pump. Then, it is heated at 450rpm and stirred for 60 minutes to obtain a silvery-white AgNWs crude solution. The centrifuge speed is controlled at 7500rpm. The AgNWs crude solution is centrifuged and washed with ultrapure water to obtain pure Ag nanowires. The pure Ag NWs are dispersed in 25mL of ultrapure water for subsequent storage and use.

[0083] Step 3: Preparation of gold and silver nanowire solution: 3 mL of 20 mM sodium hydroxide aqueous solution, 120 μL of 25.4 mM chloroauric acid aqueous solution and 19 mL of ultrapure water were added to the reactor and stirred at 500 rpm for 2 hours to obtain a mixed solution A; 50 mg of PVP was added to 5 mL of ultrapure water and heated at 60 ° C to obtain a solution B; 2 minutes later, 600 μL of 100 mM ascorbic acid AA and 600 μL of 200 mM sodium hydroxide were added to the B solution, stirred at 500 rpm for 5 minutes, and then 800 μL of the AgNWs solution prepared in the second step was added to the B solution to obtain a mixed solution C; after rapid stirring at 800 rpm for 10 minutes, the mixed solution A was dripped dropwise into the mixed solution C at a speed of one drop per 3 seconds, and continued to heat and stir at 800 rpm for 20 minutes after the dripping was completed to stop the reaction to obtain a crude AuAg NWs solution, which was centrifuged and washed with ultrapure water at 7500 rpm. The crude NWs solution was used to obtain pure AuAg NWs, which were then dispersed in 8 mL of ultrapure water for subsequent use.

[0084] The fourth step was to prepare AuAg@WP6 NWs by ultrasonic method: 0.2 mL of AuAg NWs synthesized in the third step was added with 1 mL of ultrapure water and 1.5 mg of WP6 and ultrasonicated for 2 h to prepare AuAg@WP6 NWs;

[0085] Fifth step, preparation of reduced graphene oxide by graphene oxide: 20 mg of graphene oxide GO and 15 mL of ultrapure water were added to a flask and dispersed by ultrasonic for 2 hours to obtain a GO dispersion liquid, the GO dispersion liquid was added to a reaction kettle, and 50 mL of ethanol was added, the pH of the mixed solution was adjusted with a 1 M potassium hydroxide aqueous solution and detected with pH paper, when the pH of the dispersion liquid reached 9.0-10.0, the reaction kettle was placed in an oven and heated at 85°C for two hours to obtain a product rGO precipitate, the black precipitate was dispersed by ultrasonic and centrifuged with a centrifuge and deionized water to obtain a pure rGO dispersion liquid, and dispersed in 20-25 mL of ultrapure water to obtain a 0.6 mg mL -1 of rGO dispersion liquid;

[0086] Sixth step, preparation of reduced graphene oxide-carbon nitride rGO-C3N4 by complexing graphene phase carbon nitride with graphene phase similar π conjugated structure: 5 mg of graphite phase-carbon nitride g-C3N4 was dissolved in 2 mL of isopropyl alcohol, and 450 rpm stirring was obtained 2.5 mg mL -1 of g-C3N4 suspension; 0.03 mL of g-C3N4 suspension and 0.5 mL of rGO dispersion liquid were mixed well and stirred at 450 rpm to obtain an rGO-C3N4 composite suspension;

[0087] Seventh step, 10 μL of rGO-C3N4 solution prepared in the sixth step was dropped on the surface of a glassy carbon electrode polished with alumina, and dried at 50°C, then 10 μL of AuAg@WP6 NWs solution prepared in the fourth step was dropped on the surface of the electrode, and dried at 50°C to prepare AuAg@WP6 / rGO-C3N4 composite photoelectric material for subsequent use.

[0088] The above description of the embodiments is to facilitate the understanding and use of the invention by those of ordinary skill in the art. Those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described herein to other embodiments without having to go through creative labor. Therefore, the present application is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present application without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A method for preparing functionalized gold-silver nano-alloy wire composite photoelectric material, characterized in that: The specific steps are as follows: Step 1: Preparation of anionic water-soluble [2]biphenyl extended column [6]arene WP6, the process route is as follows: ； The second step is to prepare a silver nanowire solution: 85-90 g of polyvinyl pyrrolidone with a molecular weight of 58,000 is dissolved in 5-15 mL of 1,2-propylene glycol and transferred to a 25 mL flask. The solution is heated in an oil bath at 150-170°C and stirred continuously at 450 rpm for 1-2 hours. 1-2 mL of sodium chloride dissolved in 1,2-propylene glycol is quickly added to a concentration of 1 mM. After stirring at 450 rpm for 5-10 minutes, 3-5 mL of 0.15 M silver nitrate 1, 2-propylene glycol solution is added dropwise using a syringe pump. The solution is then heated at 450 rpm and stirred for 30-60 minutes to obtain a silvery white Ag NWs crude solution. The centrifuge speed is controlled at 6500-7500 rpm. The Ag NWs crude solution is centrifuged and washed with ultrapure water to obtain pure Ag nanowires. Pure Ag is then added in 20-25 mL of ultrapure water. NWs are dispersed for subsequent preservation and use; Step 3: Preparation of gold and silver nanowire solution: 2-3 mL of 20 mM sodium hydroxide aqueous solution, 100-120 μL of 25.4 mM chloroauric acid aqueous solution and 17-19 mL of ultrapure water were added to the reactor and stirred at 500 rpm for 1-2 hours to obtain a mixed solution A; 40-50 mg of PVP was added to 3-5 mL of ultrapure water and heated at 60°C to obtain a solution B; 2 minutes later, 500-600 μL of 100 mM ascorbic acid AA and 500-600 μL of 200 mM sodium hydroxide were added to the B solution, stirred at 500 rpm for 5 minutes, and then 700-800 μL of the Ag NWs solution prepared in the second step was added to the B solution to obtain a mixed solution C; after rapid stirring at 800 rpm for 10 minutes, the mixed solution A was dripped drop by drop into the mixed solution C at a rate of one drop per 3 seconds, and continued to heat at 800 rpm until the dripping was complete. The reaction was stopped after stirring at rpm for 10-20 minutes to obtain a crude AuAg NWs solution. The crude AuAg NWs solution was centrifuged and washed with ultrapure water at 6500-7500 rpm to obtain pure AuAg NWs. The product was dispersed in 7-8 mL of ultrapure water for subsequent use. The fourth step is to prepare AuAg@WP6 NWs by ultrasonic method: take 0.1-0.2 mL of AuAg NWs synthesized in the third step, add 0.8-1 mL of ultrapure water, add 1-1.5 mg of WP6 and ultrasonicate for 1-2 hours to prepare AuAg@WP6 NWs; The fifth step is to prepare reduced graphene oxide by graphene oxide: 10-20 mg of graphene oxide GO and 10-15 mL of ultrapure water are added to a flask and dispersed by ultrasonication for 1-2 hours to obtain a GO dispersion. The GO dispersion is added to a reactor and 45-50 mL of ethanol is added. The pH of the mixed solution is adjusted with a 1 M potassium hydroxide aqueous solution and the pH value is detected with a pH test paper. When the pH of the dispersion reaches 9.0-10.0, the reactor is placed in an oven and heated at 80-85°C for two hours to obtain a product rGO precipitate. The black precipitate is ultrasonically dispersed and centrifuged and washed with deionized water to obtain a pure rGO dispersion, which is dispersed in 20-25 mL of ultrapure water to obtain 0.6 mg mL -1 rGO dispersion; Step 6: Prepare reduced graphene oxide-carbon nitride rGO-C3N4 by compounding graphene-like π-conjugated structure with graphene: 5 mg of graphene-carbon nitride g-C3N4 was dissolved in 2 mL of isopropanol and stirred at 450 rpm to obtain 2.5 mg mL -1 g-C3N4 suspension; 0.03 mL of g-C3N4 suspension and 0.5 mL of rGO dispersion were mixed thoroughly at 450 rpm to obtain rGO-C3N4 composite suspension; In the seventh step, 10 μL of the rGO-C3N4 solution prepared in the sixth step was dropped onto the surface of the glassy carbon electrode polished smooth with alumina and dried at 50°C. Then, 10 μL of the AuAg@WP6 NWs solution prepared in the fourth step was dropped onto the electrode surface and dried at 50°C to obtain the AuAg@WP6 / rGO-C3N4 composite photoelectric material for subsequent use.

2. The method for preparing the functionalized gold-silver nano-alloy wire composite photoelectric material according to claim 1, characterized in that: The second step of preparing the silver nanowire solution is specifically as follows: S1. Dissolve 87 g of polyvinylpyrrolidone (MW 58,000) in 10 mL of 1,2-propylene glycol and transfer the mixture to a 25 mL flask. Heat the mixture in an oil bath at 160 °C and stir continuously at 450 rpm for 1 hour. S2. Quickly add 1 mL of sodium chloride dissolved in 1,2-propylene glycol to a concentration of 1 mM. After stirring at 450 rpm for 5 minutes, add 4 mL of 0.15 M silver nitrate 1,2-propylene glycol solution dropwise using a syringe pump. Then heat and stir at 450 rpm for 40 minutes to obtain a silvery-white Ag NWs crude solution. S3, controlling the centrifuge speed to 7000 rpm, using a centrifuge and ultrapure water to centrifuge and wash the crude Ag NWs solution to obtain pure Ag nanowires; S4. Use 20 mL of ultrapure water to disperse the purified Ag NWs for subsequent storage and use.

3. The method for preparing a functionalized gold-silver nano-alloy wire composite photoelectric material according to claim 1, characterized in that: The third step of preparing the gold-silver nanowire solution by ion exchange method specifically comprises the following steps: Step 1: Add 2 mL of 20 mM sodium hydroxide aqueous solution, 100 μL of 25.4 mM chloroauric acid aqueous solution, and 17.9 mL of ultrapure water to the reactor and stir at 500 rpm for 1 hour at room temperature to obtain a mixed solution A; Step 2: Add 40 mg of PVP to 3 mL of ultrapure water and heat at 60°C to obtain solution B. Step 3: After 2 minutes, 500 μL of 100 mM ascorbic acid AA and 500 μL of 200 mM sodium hydroxide were added to solution B. After stirring at 500 rpm for 5 minutes, 700 μL of the Ag NWs solution prepared in the second step was added to solution B to obtain a mixed solution C. After rapid stirring at 800 rpm for 10 minutes, mixed solution A was dripped dropwise into mixed solution C at a rate of one drop per 3 seconds until the solution was completely dripped. After continued heating at 800 rpm and stirring for 10 minutes, the reaction was stopped to obtain a crude AuAg NWs solution. Step 4: The crude AuAg NWs solution was washed several times with ultrapure water by centrifugation at 7000 rpm to obtain pure AuAg NWs, and the product was dispersed in 7 mL of ultrapure water for subsequent use.

4. The method for preparing a functionalized gold-silver nano-alloy wire composite photoelectric material according to claim 1, characterized in that: In the fourth step, 0.14 mL of the AuAg NWs synthesized in the third step was taken, 0.86 mL of ultrapure water was added, and 1.26 mg of WP6 was added and ultrasonicated for 1.5 hours to prepare AuAg@WP6 NWs.

5. The method for preparing a functionalized gold-silver nano-alloy wire composite photoelectric material according to claim 1, characterized in that: The fifth step of preparing reduced graphene oxide by graphene oxide is specifically as follows: Step a: 14 mg of graphene oxide (GO) and 10 mL of ultrapure water were added to a flask and dispersed by ultrasonication for 2 h to obtain a GO dispersion. Step b: Add the GO dispersion to a reactor and add 46 mL of ethanol. Adjust the pH of the mixed solution with a 1 M potassium hydroxide aqueous solution and test the pH value with pH test paper. When the pH of the dispersion reaches 9.0-10.0, place the reactor in an oven and heat at 80°C for two hours to obtain the product rGO precipitate. Step c: Ultrasonic dispersion of the black precipitate was performed and washed with centrifugal and deionized water to obtain a pure rGO dispersion, which was then dispersed in 23 mL of ultrapure water to obtain 0.6 mg mL -1 rGO dispersion.

6. A functionalized gold-silver nano-alloy wire composite optoelectronic material prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the composite photoelectric material according to claim 6 in a novel signal switch type photoelectrochemical (PEC) sensing system, characterized in that: The surface area is 0.07 cm 2 10 μL of rGO-C3N4 composite suspension was drop-coated on the glassy carbon electrode and dried at 50 °C. Then, 10 μL of AuAg@WP6 NWs composite photoelectric material solution was drop-coated on the electrode surface and dried at 50 °C to prepare the AuAg@WP6 / rGO-C3N4 / GCE nanocomposite electrode.

8. Use of the composite photoelectric material according to claim 7 in a novel signal switch type photoelectrochemical (PEC) sensing system, characterized in that: The novel signal-switch photoelectrochemical (PEC) sensing system uses a traditional three-electrode system, with an AuAg@WP6 / rGO-C3N4 / GCE nanocomposite electrode as the working electrode, a platinum mesh as the counter electrode, and a saturated calomel electrode (SCE) as the reference electrode. A xenon lamp is used to simulate a visible light source to illuminate the AuAg@WP6 / rGO-C3N4 / GCE surface, and the shading interval time is controlled as a controllable "on-off" switch. Photoelectrochemical detection is then performed using an electrochemical workstation in a phosphate buffer solution containing serotonin.

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