CN104090006A - Polycarbazole/nitrogen-doped graphene modified electrode and its preparation method and use - Google Patents

Abstract

The invention discloses a polycarbazole/nitrogen-doped graphene modified electrode and a preparation method and application thereof. The invention adopts a two-step method of drop coating and polymerization to obtain the PCZ/N-GE modified glassy carbon electrode, so that the PCZ and N-GE components generate more obvious synergistic effect, the catalytic effect on reduction of p-nitrophenol is stronger, and the reduction potential is obviously increased. The raw materials are easy to obtain, and the dosage of the medicine is small. The preparation method is simple and quick, the repeatability is good, and the prepared electrode has good environmental stability.

Description

Polycarbazole/nitrogen-doped graphene modified electrode and its preparation method and use

technical field

The invention relates to a polycarbazole/nitrogen-doped graphene modified electrode, a preparation method and application.

Background technique

Graphene is a hexagonal honeycomb crystal structure with closely arranged carbon atoms, with a thickness of only 0.35nm. Its basic structural unit is the most stable benzene six-membered ring in organic materials. Ideal graphene has good electrical conductivity and relatively large specific surface area, so it has many unique physical, chemical and mechanical properties, and is widely used in the field of electrochemical sensors. Doping some heteroatoms such as N, B, etc. into the structure of graphene destroys the ideal SP2 hybridization of carbon atoms, thus causing significant changes in the electronic properties and chemical activity of graphene. Since the nitrogen atom is adjacent to the carbon atom in the periodic table of elements and has a lone pair of electrons, it also has good conductivity after doping. As a conductive polymer with superior performance, polycarbazole has been widely used in many fields. Copolymers of polycarbazole and its derivatives have been used as electrochemical sensors for the detection of dopamine. Lei Wu et al. used a compound of polycarbazole and graphene to modify the glassy carbon electrode to realize the detection of the pesticide imidacloprid. It has low detection limit and sensitivity. Therefore, polycarbazole has a wider application prospect in the field of electrochemical sensing.

As one of the most serious environmental pollutants, p-nitrophenol has been widely used in dyes, pesticides and explosives. Due to its special toxicity to humans, animals and plants, and it is difficult to degrade through traditional treatment methods, p-nitrophenol and its derivatives have been listed by the US Environmental Protection Agency as one of the 114 organic pollutants. Its detection is very necessary. At present, there are many methods that can be used to detect p-nitrophenol, such as gas chromatography, high performance liquid chromatography, spectrometry and so on. But these methods are very complicated. Time-consuming and expensive, not suitable for popularization and application.

Contents of the invention

The object of the present invention is to provide a polycarbazole/nitrogen-doped graphene modified electrode with excellent performance, simple and rapid preparation, a preparation method and use.

Technical solution of the present invention is:

A polycarbazole/nitrogen-doped graphene modified electrode is characterized in that: a glassy carbon electrode is used as a substrate, and a conductive polymer polycarbazole and nitrogen-doped graphene are composed.

A kind of preparation method of polycarbazole/nitrogen-doped graphene modified electrode is characterized in that: comprise the following steps:

(1) Grind the glassy carbon electrode on 0.1 and 0.03 μm alumina to smooth, rinse with water and acetone, and set aside;

(2) Dissolve a certain amount of nitrogen-doped graphene in NN-dimethylformamide, and form a dark brown uniformly dispersed mixed solution after ultrasonication; take the above mixed solution and drop it on the glass treated in step (1). on the carbon electrode. Dry under infrared lamps for later use;

(3) The electrochemical polymerization method adopts cyclic voltammetry, using a three-electrode system, a saturated calomel electrode as a reference electrode, a platinum wire electrode as a counter electrode, and a glassy carbon electrode as a working electrode. In the ether solution, adjust the low potential to -0.2~0.4V, the high potential to 1.4~1.8V, the scanning speed to 50~200mV s-1, and scan 4~12 times. The modified electrode obtained is washed repeatedly with ethanol and water, and washed with Blow dry with nitrogen to prepare PCZ/N-GE modified electrode.

A polycarbazole/nitrogen-doped graphene modified electrode is used to detect p-nitrophenol, and it is characterized in that: the detection method comprises the following steps:

Place the PCZ/N-GE modified glassy carbon electrode in a buffer solution with a pH value of 4.6, pass nitrogen gas for 10 minutes, add p-nitrophenol, and use cyclic voltammetry to detect the electrochemical reaction of the electrode to environmental pollutant p-nitrophenol response.

The buffer solution is acetic acid and sodium acetate. The concentration range of p-nitrophenol is 0.8~20μM.

Compared with the prior art, the present invention has the following remarkable advantages: (1) The PCZ/N-GE modified glassy carbon electrode is obtained by two-step method of drip coating and polymerization, so that the two components of PCZ and N-GE produce more obvious The synergistic effect makes it have a strong catalytic effect on the reduction of p-nitrophenol, and the reduction potential increases significantly. The raw materials used are easy to obtain, and the dosage of medicines is small. The preparation method is simple and fast, has good repeatability, and the prepared electrode has good environmental stability. (2) The prepared modified electrode has a strong current response on the CV curve, and the electrochemical detection of p-nitrophenol has a low detection limit (~10-8M), and the linear correlation coefficient is 0.9971. The detection method is fast and accurate.

Description of drawings

The present invention will be further described below in conjunction with drawings and embodiments.

Figure 1 is the preparation of Example 1 PCZ/N-GE of the present invention (polymerization curve of carbazole on nitrogen-doped graphene-modified glassy carbon electrode).

Fig. 2, Fig. 3 are the scanning electron micrographs of the PCZ/N-GE modified electrode prepared in Example 1 of the present invention.

Fig. 4 is the cyclic voltammetry curve of the PCZ/N-GE modified electrode prepared in Example 1 of the present invention and other modified electrodes to p-nitrophenol.

Figure 5 and Figure 6 are respectively the cyclic voltammetry curve (0.8-20 μM) and the linear relationship diagram of the PCZ/N-GE modified electrode prepared in Example 1 of the present invention in response to the current response to p-nitrophenol.

Detailed ways

Example 1:

(1) Grind the glassy carbon electrode on 0.1 and 0.03 μm alumina to smooth, rinse with water and acetone, and set aside.

(2) Nitrogen-doped graphene (N-GE) was dissolved in N,N-dimethylformamide (DMF) medium to form a solution of 2 mg ml ^-1 . Use a precision pipette to pipette 10 μL and drop it on the treated glassy carbon electrode, and dry it with an infrared lamp.

(3) Cyclic voltammetry was used as the electrochemical polymerization method, and a three-electrode system was used. The saturated calomel electrode was used as the reference electrode, the platinum wire electrode was used as the counter electrode, and the N-GE modified glassy carbon electrode was used as the working electrode. In the boron trifluoride ether solution of carbazole, adjust the low potential to 0 V, the high potential to 1.4 V, and the scanning speed to 100 mV s ^-1 , and scan 8 times. The obtained modified electrode is rinsed repeatedly with ethanol and water, and then rinsed with nitrogen gas. Blow dry to prepare PCZ/N-GE modified electrode (see Figure 1). The glassy carbon electrodes modified by N-GE and PCZ/N-GE were tested by scanning electron microscope (see Figure 2 and Figure 3). It can be seen from Figure 2 that N-GE has a typical thin paper-like structure of graphene with a large surface area. It can be seen from Figure 3 that when a layer of polycarbazole is polymerized on N-GE, the surface has a loose structure to facilitate the transfer of analytes and electrons between the solution and the electrode.

Example 2:

(1) Grind the glassy carbon electrode on 0.1 and 0.03 μm alumina to smooth, rinse with water and acetone, and set aside.

(2) Nitrogen-doped graphene (N-GE) was dissolved in N,N-dimethylformamide (DMF) medium to form a solution of 0.5 mg ml ^-1 . Use a precision pipette to pipette 10 μL and drop it on the treated glassy carbon electrode, and dry it with an infrared lamp.

(3) Cyclic voltammetry was used as the electrochemical polymerization method, and a three-electrode system was used. The saturated calomel electrode was used as the reference electrode, the platinum wire electrode was used as the counter electrode, and the N-GE modified glassy carbon electrode was used as the working electrode. In the boron trifluoride ether solution of carbazole, adjust the low potential to -0.2 V, the high potential to 1.4 V, and the scanning speed to 200 mV s ^-1 , and scan 8 times. The modified electrode obtained was washed repeatedly with ethanol and water, and washed with Blow dry with nitrogen to prepare PCZ/N-GE modified electrode.

Example 3:

(1) Grind the glassy carbon electrode on 0.1 and 0.03 μm alumina to smooth, rinse with water and acetone, and set aside.

(2) Dissolve nitrogen-doped graphene (N-GE) in a certain amount of N,N-dimethylformamide (DMF) medium to form a solution of 1 mg ml ^-1 . Use a precision pipette to pipette 10 μL and drop it on the treated glassy carbon electrode, and dry it with an infrared lamp.

(3) Cyclic voltammetry was used as the electrochemical polymerization method, and a three-electrode system was used. The saturated calomel electrode was used as the reference electrode, the platinum wire electrode was used as the counter electrode, and the N-GE modified glassy carbon electrode was used as the working electrode. In the boron trifluoride ether solution of carbazole, adjust the low potential to 0 V, the high potential to 1.8 V, and the scanning speed to 50 mV s ^-1 , and scan 8 times. The obtained modified electrode is rinsed repeatedly with ethanol and water, and then rinsed with nitrogen gas. Blow dry to prepare PCZ/N-GE modified electrode.

Example 4: The electrode prepared in Example 1 was tested with N-GE, graphene (GE), polycarbazole (PCZ) and bare glassy carbon electrodes in 0.1 mM p-nitrophenol solution for cyclic voltammetry . See Figure 4. It can be seen from the figure that the current response of N-GE and PCZ modified electrodes is many times stronger than that of bare glassy carbon, and on the N-GE modified electrode, the potential of the reduction peak is larger than that of bare glassy carbon , indicating that N-GE has a strong catalytic effect on the reduction of p-nitrophenol. The PCZ/N-GE modified electrode is many times stronger than the two, the reduction potential is more positive, and the catalytic effect is stronger, which is mainly caused by the synergistic effect of PCZ and N-GE. The PCZ/N-GE modified glassy carbon electrode can be used as an electrochemical sensor to detect p-nitrophenol quickly and conveniently.

Example 5:

The application of the PCZ/N-GE modified glassy carbon electrode prepared in Example 1 in the detection of environmental pollutant p-nitrophenol, the detection method is as follows:

The obtained PCZ/N-GE modified glassy carbon electrode was placed in an acetate buffer solution with a pH value of 4.6, nitrogen gas was passed for 10 minutes, different amounts of p-nitrophenol solutions were added, and the effect of the electrode on the environment was detected by cyclic voltammetry. Electrochemical response of pollutants to nitrophenol. The experimental results are shown in Figure 5 and Figure 6. Figure 5 is a cyclic voltammetry curve. Figure 6 shows a good linear relationship between the current and the concentration of p-nitrophenol in the range of 0.8-20 μM. The linear relationship is Ipc(μA) =0.6549+1.6531C (μM), and the correlation coefficient is 0.9971. The detection limit is 0.062 μM (S/N=3). It shows that the modified electrode has a good linear relationship and a low detection limit for p-nitrophenol.

Claims (5)

1. polycarbazole/nitrogen-doped graphene modified electrode, is characterized in that: by glass-carbon electrode, as substrate, conducting polymer polycarbazole and nitrogen-doped graphene form.

2. a preparation method for polycarbazole/nitrogen-doped graphene modified electrode, is characterized in that: comprise the following steps:

(1) glass-carbon electrode is ground to respectively on the aluminium oxide of 0.1 and 0.03 μ m smooth, water and acetone rinsing are clean, for subsequent use;

(2) a certain amount of nitrogen-doped graphene is dissolved in NN-dimethyl formamide to the finely dispersed mixed solution of ultrasonic rear formation dark-brown; Get above-mentioned mixed solution, drop on the glass-carbon electrode of handling well through step (1).Dry for standby under infrared lamp;

(3) electrochemical polymerization is selected cyclic voltammetry, uses three-electrode system, and saturated calomel electrode is contrast electrode, platinum electrode is to electrode, glass-carbon electrode is working electrode, and in the boron trifluoride ether solution that contains carbazole, adjusting electronegative potential is-0.2 ~ 0.4V, noble potential is 1.4 ~ 1.8V, sweep velocity is 50 ~ 200mV s-1, scanning 4 ~ 12 circles, and the modified electrode obtaining uses second alcohol and water repeatedly to rinse, and dry up with nitrogen, make PCZ/N-GE modified electrode.

3. polycarbazole/nitrogen-doped graphene modified electrode claimed in claim 1, for detection of a p-nitrophenol, is characterized in that: detection method comprises the following steps:

PCZ/N-GE modified glassy carbon electrode is positioned in the buffer solution of pH value 4.6, logical nitrogen 10 minutes, adds p-nitrophenol, uses cyclic voltammetry, and detecting electrode is the electrochemical response of p-nitrophenol to environmental pollutants.

4. polycarbazole/nitrogen-doped graphene modified electrode according to claim 3, for detection of p-nitrophenol, is characterized in that: buffer solution is selected acetic acid and sodium acetate.

5. polycarbazole/nitrogen-doped graphene modified electrode according to claim 3, for detection of p-nitrophenol, is characterized in that: p-nitrophenol concentration range is 0.8 ~ 20 μ M.