CN111122671A

CN111122671A - Preparation of PANI-NiO enzyme-free electrochemical sensor

Info

Publication number: CN111122671A
Application number: CN201911254863.0A
Authority: CN
Inventors: 罗士平; 朱仕超; 谢爱娟; 张江辉; 陶祥; 刘忠翔; 魏冰雁; 彭文豪
Original assignee: Changzhou University
Current assignee: Changzhou University
Priority date: 2019-12-10
Filing date: 2019-12-10
Publication date: 2020-05-08

Abstract

The invention belongs to the technical field of nano functional materials and electrochemistry, and particularly relates to a preparation method of a PANI-NiO enzyme-free electrochemical sensor. According to the invention, NiO is prepared by calcination, then a certain amount of NiO is added in the aniline solution by adopting a one-pot method for in-situ polymerization to synthesize the PANI-NiO composite material, the PANI-NiO composite material is modified on a glassy carbon electrode to prepare the PANI-NiO enzyme-free sensor, and the PANI-NiO enzyme-free sensor is used for ascorbic acid detection. The result shows that the PANI-NiO enzyme-free electrochemical sensor prepared by the invention has the advantages of simple preparation, high sensitivity and the like.

Description

Preparation of PANI-NiO enzyme-free electrochemical sensor

Technical Field

The invention belongs to the technical field of nano functional materials and electrochemistry, and particularly relates to a preparation method of a PANI-NiO enzyme-free electrochemical sensor.

Background

Ascorbic acid, also known as vitamin C, is a potent reducing agent and antioxidant and is widely found in food and human organs. The development of a simple, rapid and accurate method for detecting ascorbic acid is important for food and drug safety. Compared with the traditional ascorbic acid detection methods such as a fluorescence method, a chromatography method, a spectrophotometry method and the like, the electrochemical method has the advantages of low manufacturing cost, high sensitivity, high reaction speed, simple operation and the like. The chemically modified electrode has good selectivity and sensitivity, and is of great interest in the detection of ascorbic acid.

Conductive polymers have entered the field of vision in the last 70 th century, and have a unique conjugated structure and excellent physicochemical properties, and thus have received much attention from researchers. The conductive polymer has wide application range and has attractive application prospect in the fields of electro-variable materials, new energy sources, sensors, super capacitors, metal corrosion prevention and molecular devices. Conductive polymers are of great interest and interest to electrochemical sensor workers because of their simple synthesis process, low cost, high electrical and thermal conductivity, ability to be compounded with other materials, and ease of deposition on chemically modified electrodes.

At present, the construction and application of Polyaniline (PANI) and polyaniline composite electrochemical sensors are increasingly popularized, and the development of novel aniline composite materials with special functions, the optimization of synthetic routes and the improvement of product stability are the key points of future research. With the process trend of electronic technology and micro device processing technology becoming mature, the development of PANI composite materials with special functions is easier, and the PANI composite materials are more widely applied to the fields of electrochemical sensors and multi-level.

Metal oxides are a functional inorganic material widely used in daily life. The metal oxide is very expensive and can constitute a large number of crystal structures having various morphologies and having different electronic structures, so that the oxide can exhibit characteristics of a metal, a semiconductor, or an insulator. These different crystal structures cause the metal oxide material to have different crystal plane activities and specific surface areas, thereby affecting the physical and chemical properties of the metal oxide material. Metal oxides are often used as electrode materials because they have a porous structure, large pore diameters, and a high specific surface area, and can undergo a relatively complete redox reaction. At present, metal oxide materials with rich and various properties are widely applied to the fields of photocatalysis, sensor materials, plasma batteries and the like.

The PANI-NiO electrochemical sensor is simple to prepare, has the advantages of good reproducibility and repeatability, high stability, strong anti-interference capability and the like, and has great development prospect in the industries of food monitoring, medical care and the like.

Disclosure of Invention

Based on the reasons, the invention provides preparation of the PANI-NiO enzyme-free electrochemical sensor. The invention relates to a PANI-NiO enzyme-free electrochemical sensor which is prepared by the following specific steps:

(1) weighing 2.8986g of nickel nitrate hexahydrate and 3.1616g of sodium carbonate, placing the nickel nitrate hexahydrate and the sodium carbonate into an agate mortar, fully grinding until products are in a homogeneous light green powder shape, washing the products (three times of washing with distilled water and three times of washing with absolute ethyl alcohol), then drying the products at a constant temperature of 80 ℃, and calcining a precipitation precursor in a muffle furnace with the temperature set to be 500 ℃ for 2 hours to prepare NiO;

(2) weighing 1.0g of aniline and 0.25g of sodium dodecyl benzene sulfonate, placing the aniline and the sodium dodecyl benzene sulfonate into a 100mL beaker, adding NiO prepared in advance according to a certain proportion, and adding 40mL0.5 mol/L H₂SO₄Dissolve and mark as solution A. Then 1.5g of ammonium persulfate is weighed and dissolved in 20mL0.5mol/L H₂SO₄In (1), denoted as solution B. Slowly dripping the solution B into the solution A (about 3 seconds per drop, at the temperature of 0 ℃ and under stirring), continuously stirring for 8 hours under the condition of ice-water bath, filtering and washing to obtain a dark green product, drying in a drying oven at the temperature of 60 ℃, and grinding to obtain the PANI-NiO composite material;

(3) preparing a modified electrochemical sensor by adopting a dropping method, preparing a PANI-NiO composite material into a dispersion liquid with the concentration of 2 mg/mL, placing the dispersion liquid in an ultrasonic cleaning instrument for uniform dispersion through ultrasound, finally, accurately sucking 10 muL of the dispersion liquid by using a micropipettor, dropping and coating the dispersion liquid on a glassy carbon electrode to enable the solution to be uniformly attached to the surface of the electrode, dropping 5 muL of Nafion solution after solidification and film formation so as to enhance the stability of the modified electrode, and obtaining the polyaniline-NiO chemically modified electrode after drying and solidification again;

further, in the step (2), the ratio of aniline to sodium dodecyl benzene sulfonate is 1: 0.25; the adding amount of the ethanol is 150-200 mL.

Further, the protonic acid in step (2) may be H₂SO₄HCl, p-toluenesulfonic acid; proton(s)The addition amount of the acid is 40-60 mL, and the concentration is 0.5-1.0 mol/L.

Further, the mass ratio of the addition amount of NiO to the addition amount of aniline in the step (3) is 1-5: 5 to 1.

The invention has the beneficial effects that:

the three-dimensional nano spherical PANI-NiO non-enzymatic ascorbic acid electrochemical sensor prepared by the method has the advantages of simple preparation, high sensitivity and the like, and has great development prospect in the industries of food monitoring, medical care and the like.

Drawings

The invention will be further explained with reference to the drawings.

FIG. 1 is the XRD pattern of the PAN-NiO enzyme-free ascorbic acid electrochemical sensor in example 1.

FIG. 2 is a comparison of electrochemical performance of PAN-NiO enzyme-free ascorbic acid electrochemical sensor of comparative example 1.

Detailed Description

The invention will now be further illustrated by reference to specific examples, which are intended to be illustrative of the invention and are not intended to be a further limitation of the invention.

Example 1:

(1) 1.0g of aniline and 0.25g of sodium dodecylbenzenesulfonate are weighed into a 100mL beaker, and 40mL of 0.5 mol/LH is added₂SO₄Dissolve and mark as solution A. Then 1.5g of ammonium persulfate was weighed and dissolved in 20mL of 0.5mol/L H₂SO₄In (1), denoted as solution B. Slowly dripping the solution B into the solution A (about 3 seconds per drop, at 0 ℃ and under stirring), continuously stirring for 8 hours under the condition of ice-water bath, filtering and washing to obtain a dark green product, drying in an oven at 60 ℃, and grinding to obtain dark green homogeneous powder;

(2) weighing 2.8986g of nickel nitrate hexahydrate and 3.1616g of sodium carbonate, placing the nickel nitrate hexahydrate and the sodium carbonate into an agate mortar, fully grinding the mixture until the product is in a homogeneous light green powder state, washing the product (three times of washing by distilled water and three times of washing by absolute ethyl alcohol), then drying the product at a constant temperature of 80 ℃, and calcining a precipitation precursor in a muffle furnace with the temperature set to 500 ℃ for 2 hours to obtain nickel oxide;

(3) by one-pot method for preparing polyanilineMeanwhile, a certain proportion of NiO prepared in advance is added to prepare a composite material PANI-NiO of the two, FIG. 1 is an XRD pattern of the PAN-NiO enzyme-free ascorbic acid electrochemical sensor in example 1, and the diffraction angle is 2θTwo peaks appear in the angle of 21 degrees and 25 degrees, which are consistent with the characteristic peaks of polyaniline in the literature, and the characteristic peaks of nickel oxide appear in other diffraction angles, so that the successful preparation of PANI/NiO can be judged.

(4) Preparing a modified electrochemical sensor by adopting a dropping method, and preparing the PANI-NiO composite material into a material with the concentration of 2 mg.mL^-1The dispersion liquid is placed in an ultrasonic cleaning instrument to be dispersed uniformly through ultrasound, finally, a micropipettor is used for accurately sucking 10 mu L of the dispersion liquid, the dispersion liquid is dripped on a glassy carbon electrode, the solution of the dispersion liquid is uniformly attached to the surface of the electrode, 5 mu L of LNafion solution is dripped after the dispersion liquid is solidified into a membrane so as to enhance the stability of a modified electrode, and the polyaniline-NiO chemically modified electrode, namely the enzyme-free electrochemical sensor, is obtained after the dispersion liquid is dried and solidified again.

Example 2:

the PANI-NiO enzyme-free ascorbic acid electrochemical sensor is placed in PBS buffer solution containing 0.20 mmol/L ascorbic acid, pH = 7.0 and 0.20 mol/L, and forms a three-electrode system with a Pt sheet electrode and a calomel electrode, the scanning speed is set to be 100 mV/s, the mass ratio of aniline to NiO is 5:1, and cyclic voltammetry curve determination is carried out.

Comparative example 1:

the mass ratio of aniline to NiO in example 1 is changed to 1:1 and 3:1, and the rest conditions are controlled to be unchanged, so that the PANI-NiO enzyme-free electrochemical sensor is synthesized. The ascorbic acid response effect in the phosphate buffer solution of PBS was measured by the same measurement method as in example 2. The test result shows that the electrochemical performance of the PANI-NiO (5:1) without enzyme is obviously superior to that of the PANI-NiO (1:1) and the PANI-NiO (3:1) (shown in the attached figure 2). The PANI-NiO (5:1) enzyme-free electrochemical sensor prepared by the method has stronger electrochemical activity in the detection of ascorbic acid compared with PANI-NiO (1:1) and PANI-NiO (3: 1).

Claims

1. The preparation method of the PANI-NiO enzyme-free electrochemical sensor is characterized by comprising the following main steps of:

(2) weighing 1.0g of aniline and 0.25g of sodium dodecyl benzene sulfonate, placing the aniline and the sodium dodecyl benzene sulfonate into a 100mL beaker, adding NiO prepared in advance according to a certain proportion, and adding 40mL0.5 mol/L H₂SO₄Dissolving and marking as A liquid; then 1.5g of ammonium persulfate is weighed and dissolved in 20mL0.5mol/L H₂SO₄In (1), marking as liquid B; slowly dripping the solution B into the solution A (about 3 seconds per drop, at the temperature of 0 ℃ and under stirring), continuously stirring for 8 hours under the condition of ice-water bath, filtering and washing to obtain a dark green product, drying in a drying oven at the temperature of 60 ℃, and grinding to obtain the PANI-NiO composite material;

(3) preparing a modified electrochemical sensor by adopting a dropping method, preparing a PANI-NiO composite material into a dispersion liquid with the concentration of 2 mg/mL, placing the dispersion liquid in an ultrasonic cleaning instrument for uniform dispersion through ultrasound, finally, accurately sucking 10 muL of the dispersion liquid by using a micropipettor, dropping and coating the dispersion liquid on a glassy carbon electrode to enable the solution to be uniformly attached to the surface of the electrode, dropping 5 muL of Nafion solution after solidification and film formation so as to enhance the stability of the modified electrode, and obtaining the polyaniline-NiO chemically modified electrode after drying and solidification again.

2. The method for preparing the PANI-NiO enzyme-free electrochemical sensor according to claim 1, wherein the electrochemical sensor comprises: in the step (2), the ratio of aniline to sodium dodecyl benzene sulfonate is 1: 0.25; the adding amount of the ethanol is 150-200 mL.

3. The method for preparing the PANI-NiO enzyme-free electrochemical sensor according to claim 1, wherein the electrochemical sensor comprises: the protonic acid in the step (2) may be H₂SO₄HCl, p-toluenesulfonic acid; the addition amount of the protonic acid is 40-60 mL, and the concentration is 0.5-1.0 mol/L.

4. The method for preparing the PANI-NiO enzyme-free electrochemical sensor according to claim 1, wherein the electrochemical sensor comprises: the mass ratio of the addition amount of NiO to the addition amount of aniline in the step (3) is 1-5: 5 to 1.