CN111595914B

CN111595914B - Preparation method of titanium oxide nanotube array-based photoelectrochemical detection electrode

Info

Publication number: CN111595914B
Application number: CN202010589940.4A
Authority: CN
Inventors: 赵建玲; 吴志刚; 王西新; 刘东鑫; 朱淼
Original assignee: Hebei University of Technology
Current assignee: Hebei University of Technology
Priority date: 2020-06-24
Filing date: 2020-06-24
Publication date: 2022-06-07
Anticipated expiration: 2040-06-24
Also published as: CN111595914A

Abstract

The invention relates to a preparation method of a titanium oxide nanotube array-based photoelectrochemical detection electrode. According to the method, Ag is used for modifying TNTA to prepare Ag-TNTA, and then metal silver and copper are deposited in the Ag-TNTA through chemical codeposition and hydrothermal reduction to prepare the electrode. The photoelectrochemical detection electrode prepared by the method can be used for detecting permanganate and dopamine, and is simple and quick in test process and free of pollution.

Description

Preparation method of titanium oxide nanotube array-based photoelectrochemical detection electrode

Technical Field

The invention belongs to the technical field of analysis and detection, and particularly relates to a preparation method of a photoelectrochemistry detection electrode.

Background

Because heavy metal elements are widely applied in many fields, a large amount of heavy metal ions enter a water body to cause heavy metal ion pollution, and serious harm is caused to human health, animals, plants and the like. For example, dopamine is a catecholamine neurotransmitter, a chemical substance used by intracerebral information transmitters to help cells to deliver impulses and regulate various physiological functions of the central nervous system. This brain endocrine is related to the emotion, sensation and transmits information about excitement and distraction. In addition, dopamine is also associated with various addictive behaviors. During manganese poisoning, levodopa decarboxylase is inhibited, so that the process of decarboxylating levodopa into dopamine and norepinephrine is hindered, and the content of dopamine and norepinephrine in basal ganglia is obviously reduced. Disorders of dopamine system regulation are involved in the development of parkinson's disease, schizophrenia, tourette syndrome, attention deficit hyperactivity syndrome, and pituitary tumors, among others.

The detection of heavy metal ions is the basis for preventing and treating heavy metal ion pollution. The methods for detecting heavy metal ions are various, and the analysis methods of instruments such as atomic absorption spectroscopy, mass spectrometry, fluorescence spectroscopy, Raman spectroscopy and the like need expensive, heavy and complex instruments, so that the detection cost is high, the steps are multiple, the time consumption is long, and the popularization is not easy; the chemical analysis method needs a plurality of chemical reagents, and has the problems of secondary pollution besides multiple steps and long time consumption; the electrochemical analysis method is a method for determining the quantity of a substance to be measured in a solution according to a certain relation between the quantity and certain electrical parameters (such as resistance, conductance, potential, current, electric quantity and the like), and has the characteristics of simple operation, low cost, high detection speed and easiness in realizing miniaturization and automation.

Photoelectrochemical detection is an analytical technique developed on the basis of electrochemical analysis, which is carried out based on the existence of a certain relationship between an electrochemical signal generated when a detection electrode is irradiated with light and the amount of a substance to be detected in a solution. The key of the photoelectrochemical detection is a detection electrode, and the photoelectrochemical method is adopted to detect substances such as heavy metal ions, dopamine and the like. For example, Analytical Chemistry (2010, 82, P2253-. Biosensors and Bioelectronics (2007, 22, P2812-2818) report a preparation method of a photoelectrochemical detection electrode, a titanium oxide nanotube array (TiO) is grown on the surface of a Ti sheet by an anodic oxidation method₂Ti electrode) and then impregnating the TiO with a Glucose Oxidase (GOD) solution₂a/Ti electrode, finally depositing polypyrrole on the sample through electropolymerization, fixing GOD and preparing the TiO modified by GOD₂Ti electrode (GOD-TiO)₂a/Ti electrode) which can be used for the photoelectrochemical detection of glucose. Microchim Acta (2017, 184, P3333-3338) reports a preparation method of a photoelectrochemical detection electrode, SnSe nanosheets are prepared by a solvothermal method, then the SnSe nanosheets are dispersed and dripped on the surface of a cleaned gold electrode, and the gold electrode modified by SnSe (SnSe/GE) can be obtained by natural drying in the air, and the electrode can be used for photoelectrochemical detection of dopamine. Microchim Acta (2017, 184, P4827-4833) reports a preparation method of a photoelectrochemical detection electrode, wherein nitrogen-doped carbon quantum dots (N-CDs) can be obtained by heating and refluxing an ammonium citrate solution at 200 ℃; preparation of BiVO by hydrothermal method₄Powder of BiVO₄Dispersing the powder into dilute hydrochloric acid to prepare a dispersion solution, then adding N-CDs, stirring and dispersing uniformly, transferring into a hydrothermal kettle for hydrothermal reaction to prepare BiOCl/BiVO₄a/N-CDs composite powder; using BiOCl/BiVO₄Preparing dispersion liquid from the/N-CDs composite powder, dripping the dispersion liquid on the surface of the cleaned ITO electrode, and drying in the air at room temperature to prepare the electrode (BiOCl/BiVO)₄/N-CDs/ITO) that can be used for the photoelectrochemical detection of dopamine. The biosensor and Bioelectronics (2014, 56, P243-249) reports a preparation method of a photoelectrochemical detection electrode, ITO glass is used as a substrate, zinc oxide nanoflower is firstly deposited on the surface of the ITO glass by a hydrothermal method, then a DNA film is deposited by electrostatic adsorption, and the zinc oxide nanoflower-based electrode can be prepared and can be used for Pb²⁺Photoelectrochemical detection of (1). However, no report on a photoelectrochemical electrode which can be used for detecting both permanganate and dopamine is available at present. In addition, the photoelectrochemical sensor reported in the literature has some disadvantages and shortcomings, for example, the photoelectrochemical sensor containing enzyme is generally poor in stability, and the photoelectrochemical sensor prepared by the coating method has the problems that the active substance is easy to agglomerate, the dosage is not easy to control, the conductivity is poor, and the like.

The photoelectric chemical detection is a testing method with high speed, low cost and no secondary pollution, and the research contents mainly comprise the development of a new electrode which can be used for detecting different substances, the simplification of the preparation process of the electrode, the reduction of the preparation cost of the electrode, the improvement of the detection performance of the electrode and the like.

Disclosure of Invention

The invention aims to provide a preparation method of a titanium oxide nanotube array-based photoelectrochemical detection electrode aiming at the defects in the prior art. According to the method, Ag is used for modifying TNTA to prepare Ag-TNTA, and then metal silver and copper are deposited in the Ag-TNTA through chemical codeposition and hydrothermal reduction to prepare the electrode. The electrode obtained by the invention can detect both permanganate acid radicals and dopamine.

The technical scheme of the invention is as follows:

a preparation method of a titanium oxide nanotube array-based photoelectrochemical detection electrode comprises the following steps:

(1) inserting the cleaned Ti sheet into the mixed solution, using the Ti sheet as an anode and the Pt sheet as a cathode, carrying out anodic oxidation for 2-4 hours under the conditions that the temperature is 35-45 ℃ and the voltage is 35-45V, and after the reaction is finished, washing and drying to obtain a metallic titanium sheet with a titanium dioxide nanotube array film (TNTA) generated on the surface;

wherein the mixed solution comprises ammonium fluoride, distilled water and glycol, and the mass ratio is as follows: ammonium fluoride, distilled water and ethylene glycol 0.1 to 0.2: 2.5-7.5: 42.5 to 47.5;

(2) soaking the titanium sheet attached with the TNTA in a silver ion solution for 5-15 min, soaking the titanium sheet in a 0.05-0.20M NaOH solution for 5-15 min after washing, and then soaking the sample sheet in distilled water for 3-5 min; after the process of 'silver ion solution soaking-NaOH solution soaking-distilled water soaking' is carried out for 1-9 times, the material is taken out and calcined for 1-3 hours at the temperature of 430-460 ℃, and the Ag modified TNTA (marked as Ag-TNTA) is obtained;

wherein the silver ion solution is silver nitrate solution with the concentration of 0.01-0.05M, and contains 0.01-0.1M nitric acid and 0.01-0.1M surfactant;

(3) firstly, soaking Ag-TNTA in a copper-silver ion mixed solution for 5-15 min, after washing, soaking in a 0.05-0.20M NaOH solution for 5-15 min, and then soaking a sample wafer in distilled water for 3-5 min; after the process of soaking in a copper silver ion solution, soaking in a NaOH solution and soaking in distilled water is carried out for 1-9 times, taking out the material to obtain a copper silver hydroxide/Ag-TNTA sample wafer;

and after the steps are completed, putting the copper-silver hydroxide/Ag-TNTA sample wafer into a hydrothermal reaction kettle with a polytetrafluoroethylene lining, adding a reducing solution to immerse the sample wafer, carrying out hydrothermal reaction at the temperature of 120-140 ℃ for 5-7 h, cooling, washing, and airing at room temperature to obtain the photoelectric detection electrode (marked as Ag-Cu/Ag-TNTA).

The copper-silver ion mixed solution is a mixed solution of copper nitrate and silver nitrate with the total concentration of 0.05-0.1M, the molar ratio of the copper nitrate to the silver nitrate is 1: 9-9: 1, and the mixed solution contains 0.01-0.1M nitric acid and 0.01-0.1M surfactant.

The reducing solution is 0.1-0.5M NaOH solution containing a reducing agent, the reducing agent is glucose, hydrazine hydrate or formaldehyde, and the addition amount of the reducing agent is 0.1-1.0 g added into 100ml of NaOH solution.

The surfactant in the steps (2) and (3) is ethanolamine.

The titanium oxide nanotube array-based photoelectrochemical detection electrode can be used for detecting permanganate acid radicals and dopamine.

The invention has the beneficial effects that:

(1) the invention has the outstanding characteristics that the prepared photoelectrochemistry detection electrode can be used for detecting permanganate and dopamine, and the detection process is simple, rapid and pollution-free.

(2) The method has the remarkable characteristics that silver oxide (silver hydroxide) is firstly deposited in the newly prepared TNTA, and then the sample wafer is calcined at 450 ℃ to prepare the Ag modified TNTA (Ag-TNTA). The newly prepared TNTA is in an amorphous structure, silver ions easily enter the titanium oxide, the titanium oxide is crystallized in the calcining process, and the silver oxide is converted into metal silver and doped in the titanium oxide. The modification of TNTA with Ag can raise the conductivity of TNTA and facilitate the combination of metal particle deposited in the subsequent step and TNTA.

(3) The method has the remarkable characteristics that Ag-TNTA is taken as a substrate, a compound of silver oxide and copper hydroxide is firstly deposited in the Ag-TNTA, and then the compound is reduced into metal silver and copper by adopting a hydrothermal method. The sample prepared by the method has the advantages of fine metal particles, more defects and more uniform dispersion, and can improve the sensitivity of the electrode. In addition, the hydrothermal reduction can also increase the number of hydroxyl groups on the surface of the titanium oxide and reduce the interfacial tension between the electrode and the aqueous solution.

(4) The invention is characterized in that ethanolamine is added into the metal ion solution as a surfactant. The amino group of the ethanolamine can be complexed with silver ions and copper ions, and the hydroxyl group of the ethanolamine can act with the hydroxyl group on the surface of the titanium oxide, so that the interfacial tension between the metal ion solution and the titanium oxide is reduced, and the combination between the metal ions and the titanium oxide is promoted; in addition, the ethanolamine has a certain volume and also has the functions of dispersing metal particles, inhibiting the agglomeration and growth of the metal particles and the like, so that the ethanolamine added into the metal ion solution is beneficial to the uniform dispersion and deposition of the metal ions in the TNTA.

(5) The invention has the obvious characteristic that the silver oxide and the copper hydroxide are deposited by adopting a chemical precipitation process for many times, so that the deposition dispersion uniformity of the deposit in the TNTA can be improved.

(6) The invention is characterized in that the titanium oxide nanotube array is adopted to prepare the photoelectrochemical detection electrode. The titanium oxide nanotube array has a large specific surface area and a highly ordered tubular structure, which is beneficial to improving the response signal intensity of the electrode.

The testing principle of the photoelectrochemical detection electrode prepared by the invention is as follows:

titanium oxide is a semiconductor material, when the titanium oxide is irradiated by light, electron-hole pairs are generated, electrons and holes are separated, the holes are transferred to the surface of the titanium oxide, the holes on the surface of the titanium oxide react with water molecules or hydroxyl radicals to be consumed due to the oxidation performance of the holes, and the electrons are transferred to an external circuit to form a photocurrent. The magnitude of the photocurrent is closely related to the consumption rate of holes, and factors such as the type of metal and the modification method affect the surface state of the electrode, so that the selectivity of the electrode and the photocurrent (the consumption rate of holes) are changed.

The Ag-Cu/Ag-TNTA electrode can be used for photoelectrochemical detection of permanganate and dopamine. When dopamine exists in the detection solution, the dopamine is easily oxidized, so that the consumption of photogenerated holes on the surface of the electrode is accelerated, and the photocurrent is increased. When permanganate radicals exist in the detection solution, the permanganate radicals have strong oxidizing property and carry negative charges, and the permanganate radicals can be adsorbed on the surface of an electrode to block and inhibit the oxidation reaction of holes, so that the photocurrent is reduced. The more the amount of permanganate and dopamine is, the stronger the corresponding influence effect is, and the larger the change of photocurrent is, so that the detection of the permanganate and dopamine can be realized.

Drawings

FIG. 1 is a photocurrent response curve (target concentration 2mM) of Ag-Cu/Ag-TNTA electrode prepared in example 1 of the present invention.

FIG. 2 is a photocurrent response curve (target concentration 2mM) of the Cu/Ag-TNTA electrode prepared in example 1 of the present invention.

FIG. 3 is a photocurrent response curve of Ag/Ag-TNTA electrode prepared in example 1 of the present invention (target concentration 2 mM).

The invention is further illustrated by the following examples in conjunction with the drawings.

The specific implementation mode is as follows:

example 1

(1) The Ti sheet (10 mm. times.20 mm. times.0.3 mm) was ultrasonically cleaned with ethanol and distilled water to remove oil stains on the surface of the Ti sheet. Preparing a mixed solution by using 0.15g of ammonium fluoride, 5g of distilled water and 45g of ethylene glycol, inserting 10mm of the lower end of a Ti sheet into the mixed solution, using the Ti sheet as an anode and a Pt sheet as a cathode, and carrying out anodic oxidation for 3 hours under the conditions that the temperature is 40 ℃ and the voltage is 40V to generate a titanium dioxide nanotube array film (marked as TNTA) on the surface of the metal titanium sheet; after the reaction is finished, the sample wafer is washed by distilled water and dried.

(2) A0.03M silver nitrate solution containing 0.05M nitric acid and 0.05M ethanolamine was prepared. The TNTA is firstly put into 10ml of silver nitrate solution to be soaked for 10min, then distilled water is used for washing off redundant solution on the surface of the sample wafer, 10ml of 0.1M NaOH solution is put into the sample wafer to be soaked for 10min, and finally the sample wafer is put into the distilled water to be soaked for 5 min. The above process was repeated 3 times. After the above experimental procedure was completed, the swatches were calcined at 450 ℃ for 2h to obtain Ag-modified TNTA (labeled as Ag-TNTA).

(3) A mixed solution of copper and silver ions containing 0.05M nitric acid, 0.05M ethanolamine, 0.03M silver nitrate and 0.03M copper nitrate was prepared. And (2) firstly soaking Ag-TNTA in 10ml of copper-silver ion mixed solution for 10min, then washing off redundant solution on the surface of the sample wafer by using distilled water, soaking in 10ml of 0.1M NaOH solution for 10min, and finally soaking the sample wafer in distilled water for 5 min. The above process was repeated 4 times. After the above steps were completed, the coupons were placed in a 25ml teflon lined hydrothermal reaction kettle.

1.0g of glucose was added to 100ml of a 0.25M NaOH solution, and dissolved by stirring to prepare a reducing solution. And adding 15ml of reducing solution into a hydrothermal reaction kettle, carrying out hydrothermal reaction for 6 hours at 130 ℃, cooling, washing, and airing at room temperature to obtain the photoelectric detection electrode (marked as Ag-Cu/Ag-TNTA).

For comparison with Ag-Cu/Ag-TNTA electrodes, Cu/Ag-TNTA and Ag/Ag-TNTA electrodes were prepared by the conditioning process:

Cu/Ag-TNTA electrode: and (4) changing the mixed solution of copper and silver ions containing 0.03M of silver nitrate and 0.03M of copper nitrate in the step (3) into a 0.06M copper nitrate solution, and preparing the electrode under the other conditions.

Ag/Ag-TNTA electrode: and (4) changing the mixed solution of copper and silver ions containing 0.03M of silver nitrate and 0.03M of copper nitrate in the step (3) into 0.06M of silver nitrate solution, and preparing the electrode under the unchanged other conditions.

A conventional three-electrode system is adopted to carry out a photoelectric detection experiment, the prepared sample is taken as a working electrode, a platinum sheet is taken as a counter electrode, a Saturated Calomel Electrode (SCE) is taken as a reference electrode, and the electrolyte is 0.5M Na₂SO₄A solution; A500W xenon lamp (CHF-XM-500W, Beijing, China) is used as a visible light source, and the distance between a sample wafer and the xenon lamp is 50 cm. The photocurrent response before and after the addition of the target object to the electrolyte was tested by an electrochemical workstation (CHI660, shanghai chenhua), and the results are shown in fig. 1, 2 and 3. The current densities detected by the electrode pairs for different targets can be obtained from FIGS. 1, 2 and 3, and are shown in Table 1 ("+" indicates increase in photocurrent density)Large, "-" indicates a decrease in photocurrent density). As can be seen from Table 1, the Cu/Ag-TNTA electrode is only active to permanganate and dopamine, and the Ag/Ag-TNTA electrode is active to Zn²⁺、Cu²⁺The high manganese acid radical and the dopamine are all active, the Ag-Cu/Ag-TNTA electrode only has activity on the high manganese acid radical and the dopamine, and the detection current density is obviously higher than that of the Cu/Ag-TNTA electrode and the Ag/Ag-TNTA electrode, so that the selectivity and the detection sensitivity of the electrode are improved due to the codeposition of copper and silver. The reasons for this result are: when copper and silver are co-deposited, the two metals have the function of mutually inhibiting growth, so that the particle size of metal particles can be reduced, and the defects and the surface energy of the metal particles can be improved; meanwhile, the two metals can generate a synergistic effect, so that the active sites on the surface of the electrode are increased.

TABLE 1 detection Current Density (Δ I, μ A/cm) of each electrode for different targets²)

Target object	Zn²⁺	Cu²⁺	H₂O₂	MnO₄ ^-	Dopamine
						Ag-Cu/Ag-TNTA	0	0	0	-45.3	+46.2
Cu/Ag-TNTA	0	0	0	-10.7	+10.0
						Ag/Ag-TNTA	+14.0	+15.5	0	-34.2	+5.5

Example 2

(1) 0.1g of ammonium fluoride, 7.5g of distilled water and 42.5g of ethylene glycol were used to prepare an electrolyte, and the procedure was the same as in example 1(1), and the electrolyte was anodized at 35 ℃ and 45V for 2 hours to prepare TNTA.

(2) 0.05M silver nitrate solution containing 0.1M nitric acid and 0.1M ethanolamine is prepared, the process steps are the same as those of example 1(2), and Ag-TNTA is prepared by codeposition for 2 times.

(3) A mixed solution of copper and silver ions containing 0.01M nitric acid, 0.01M ethanolamine, 0.005M silver nitrate and 0.045M copper nitrate was prepared, and the deposition process was the same as in example 1(3) and was carried out for 10 times.

0.5g of hydrazine hydrate was added to 100ml of a 0.5M NaOH solution, and dissolved by stirring to prepare a reducing solution. The Ag-Cu/Ag-TNTA electrode can be prepared by performing hydrothermal reduction reaction under the process conditions of the embodiment 1 and 3.

Example 3

(1) 0.2g of ammonium fluoride, 2.5g of distilled water and 47.5g of ethylene glycol were used to prepare an electrolyte, and the procedure of example 1(1) was followed to conduct anodic oxidation at 45 ℃ and 35V for 4 hours to prepare TNTA.

(2) Preparing 0.01M silver nitrate solution containing 0.01M nitric acid and 0.01M ethanolamine, the process steps are the same as those of example 1(2), and preparing Ag-TNTA by codeposition for 9 times.

(3) A mixed solution of copper and silver ions containing 0.1M nitric acid, 0.1M ethanolamine, 0.09M silver nitrate and 0.01M copper nitrate was prepared, and the deposition process was the same as in example 1(3) and was performed for 2 times.

0.1g of formaldehyde was added to 100ml of a 0.1M NaOH solution, and dissolved by stirring to prepare a reducing solution. The Ag-Cu/Ag-TNTA electrode can be prepared by performing hydrothermal reduction reaction under the process conditions of the embodiment 1 and 3.

The invention is not the best known technology.

Claims

1. A preparation method of a titanium oxide nanotube array-based photoelectrochemical detection electrode is characterized by comprising the following steps:

the mixed solution comprises ammonium fluoride, distilled water and ethylene glycol, wherein the mass ratio of the ammonium fluoride to the distilled water to the ethylene glycol is 0.1-0.2: 2.5-7.5: 42.5 to 47.5;

(2) soaking the titanium sheet attached with the TNTA in a silver ion solution for 5-15 min, soaking the titanium sheet in a 0.05-0.20M NaOH solution for 5-15 min after washing, and soaking the sample sheet in distilled water for 3-5 min; after the process of 'silver ion solution soaking-NaOH solution soaking-distilled water soaking' is carried out for 1-9 times, the material is taken out and calcined for 1-3 hours at the temperature of 430-460 ℃, and the Ag modified TNTA (marked as Ag-TNTA) is obtained;

wherein the silver ion solution is a silver nitrate solution with the concentration of 0.01-0.05M, and contains 0.01-0.1M nitric acid and 0.01-0.1M surfactant;

after the steps are completed, putting the copper-silver hydroxide/Ag-TNTA sample wafer into a hydrothermal reaction kettle with a polytetrafluoroethylene lining, adding a reducing solution to immerse the sample wafer, carrying out hydrothermal reaction at the temperature of 120-140 ℃ for 5-7 h, cooling, washing, and airing at room temperature to obtain a photoelectric detection electrode (marked as Ag-Cu/Ag-TNTA);

the copper-silver ion mixed solution is a mixed solution of copper nitrate and silver nitrate with the total concentration of 0.05-0.1M, the molar ratio of the copper nitrate to the silver nitrate is 1: 9-9: 1, and the mixed solution contains 0.01-0.1M of nitric acid and 0.01-0.1M of surfactant;

2. The method for preparing the titanium oxide nanotube array-based photoelectrochemical detection electrode according to claim 1, wherein the surfactant used in the steps (2) and (3) is ethanolamine.

3. The titanium oxide nanotube array-based photoelectrochemical detection electrode prepared by the method of claim 1, wherein the electrode is used for detection of permanganate and dopamine.