CN104730115A - Novel biological and gas sensor based on bionic honeycomb coal aerogel material - Google Patents

Abstract

The invention discloses a biological and gas sensor based on a novel bionic honeycomb carbon airgel material, which includes a built-in metal electron collector and a carbon airgel electrode material. The sensor of the present invention can be prepared by rapidly freeze-drying the graphene oxide/carbon nanotube/nafion mixed solution, and the pore size and specific surface area of the material can be controlled by changing the mixing ratio of the three. At the same time, the present invention molds the device through rapid freeze-drying, and can control the size of the electrode through the control of the size of the template. This processing method is fast and simple, and it is relatively easy to realize the transformation from the laboratory to the industry. It is proved by experiments that the present invention can be used for the detection of harmful components in the air such as acetone, chloroform and other harmful organic vapors, and plays the role of a gas sensor. And it can be used as a biosensor to detect dopamine.

Description

Novel biological and gas sensors based on biomimetic honeycomb carbon airgel materials

technical field

The invention belongs to the technical field of sensors, and relates to a high-precision three-dimensional sensor and a preparation method thereof.

Background technique

New carbon materials represented by graphene and carbon nanotubes have become research hotspots in the past ten years due to their good electrical conductivity, thermal conductivity, high specific surface area and excellent mechanical properties and have been widely used in supercapacitors, lithium-ion Batteries, organic electronic components, environmental and biosensors, and biointerface materials. However, with the deepening of research in recent years, researchers have found that when carbon nanotubes and graphene are applied to these fields, due to the stacking of materials during the processing of devices, the effective working area of the materials is greatly reduced. , which seriously limits the application performance of the device.

In the past two or three years, in order to further increase the effective working area of materials based on graphene and carbon nanotubes, researchers have devoted more and more energy to the preparation of carbon-based three-dimensional materials. The study found that compared with the two-dimensional structure of the film, the three-dimensional structure made of graphene and carbon nanotubes has a higher specific surface area per unit volume, so in applications requiring high specific surface area, such as biosensors, gas Sensors, supercapacitors, etc. all have superior performance. However, how to quickly and easily prepare structure-controllable carbon airgel materials and how to prepare them into effective sensors is still a challenge.

Contents of the invention

In view of this, the object of the present invention is to provide a method for preparing a biological and environmental sensor based on bionic honeycomb carbon aerogel, which is convenient to operate, strong in controllability, low in preparation cost, and suitable for large-scale industrial production.

In order to achieve the above object, after research, the present invention provides the following technical solutions:

1. Biological and chemical sensors based on bionic honeycomb carbon airgel materials, including rod-shaped bionic honeycomb carbon airgel electrodes and metal electron collectors built into the carbon airgel electrodes. The electron collector is embedded in the rod-shaped biomimetic honeycomb carbon airgel electrode, and forms an effective connection with the carbon airgel electrode during the freeze-drying process.

The material constituting the biomimetic honeycomb carbon airgel electrode is graphene oxide/multi-walled carbon nanotube/nafion mixture, and the material constituting the metal electron collector is copper wire, platinum wire, gold wire and the like.

The preparation method of the biological and gas sensor based on the biomimetic honeycomb carbon airgel material comprises the following steps:

1) Mix graphene oxide and multi-walled carbon nanotubes according to a certain ratio, use an ultrasonic pulverizer to process them, and then use ultrasonication in a water bath to uniformly mix the prepared graphene oxide and multi-walled carbon nanotubes.

2) The prepared graphene oxide/multi-walled carbon nanotube mixed solution was mixed with nafion in a certain proportion, and the water bath was ultrasonically mixed.

3) Put the prepared mixed solution into a syringe, and connect the syringe with a stainless steel flat needle.

4) Place the wire electron collector in the stainless steel flat needle, and push the syringe to fill the needle with the mixed solution.

5) Place the stainless steel needle in liquid nitrogen for quick freezing.

6) Take the needle and syringe out of the liquid nitrogen and place it for one minute. After the periphery melts slightly, push it hard, and put the stick in the needle back into the liquid nitrogen to freeze.

7) Freeze-drying the obtained rods to obtain graphene oxide rod-shaped carbon airgel electrodes.

8) Change the proportion of graphene oxide/multi-walled carbon nanotubes/nafion to realize the control of electrode morphology and pore size.

9) Graphene carbon airgel biological and gas sensors were obtained by heating reduction or hydrazine vapor reduction.

Beneficial effects of the present invention: the present invention prepares a porous rod-shaped sensor with a three-dimensional structure by liquid nitrogen rapid freeze-drying method, which effectively improves the characteristic specific surface area of the sensor, and realizes the control of the three-dimensional structure pore size and the control of the electrical conductivity through the existence of nafion. The improvement and enhancement of the technology have realized the effective detection of dopamine molecules and harmful gas molecules such as acetone. At the same time, the invention has low cost and is easy to prepare, and the rod-shaped electrode is also conducive to realizing the monitoring of biological processes in the body, and is suitable for applications such as biological tissue engineering and harmful gas monitoring.

Description of drawings

Figure 1: (a) Schematic diagram of the structure of the biomimetic honeycomb carbon airgel biological and gas sensor; (b) is the cross-sectional view of (a); 1 is the carbon airgel electrode, and 2 is the wire electron collector.

Figure 2: Schematic diagram of the construction process and morphology of the biomimetic honeycomb carbon airgel biological and gas sensor; (a) carbon airgel biological and gas sensor with a diameter of 0.6 mm and a built-in diameter of 100 micron platinum wire; (b) rod-shaped Cross-sectional SEM image of the carbon airgel biosensor; (c) SEM image of the side of the rod-shaped carbon airgel sensor; (d) Schematic diagram of the pore structure of the rod-shaped carbon airgel biosensor and gas sensor.

Figure 3: When the molar ratio of graphene oxide and multi-walled carbon nanotubes in the biomimetic honeycomb carbon airgel sensor is 2:1, the SEM images of airgel at different nafion concentrations; (a) nafion concentration is 0 (b ) The concentration of nafion is 25%; (c) The concentration of nafion is 16.7% (d) The concentration of nafion is 9.1%.

Figure 4: Response of biomimetic cellular carbon airgel sensor to harmful acetone vapor.

Figure 5: (a) Cyclic voltammetry curves of the hydrazine-reduced biomimetic honeycomb carbon airgel electrode in the presence of different concentrations of dopamine molecules; (b) DPV curves of the hydrazine-reduced biomimetic honeycomb carbon airgel sensor at different dopamine concentrations; (c ) Fitting curve of peak current in Fig. 5(a); (d) Fitting curve of peak current in Fig. 5(b).

Detailed ways

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The experimental methods for which specific conditions are not indicated in the preferred embodiments are usually carried out according to conventional conditions, or according to the conditions suggested by the reagent manufacturer.

The structure of the biomimetic honeycomb carbon airgel biological and gas sensor is shown in Figure 1, 1 is the built-in metal wire electron collector, and 2 is the carbon airgel electrode. The preparation process of the biomimetic honeycomb carbon airgel electrode is shown in Figure 2. The carbon airgel biological and gas sensor is prepared by liquid nitrogen quick freezing and freeze drying. The carbon airgel material is composed of graphene oxide, multi-walled carbon nanotubes and nafion. Graphene oxide is synthesized by our laboratory according to the Hummers method. The specific steps for preparing the sensor are as follows:

1) Mix graphene oxide and multi-walled carbon nanotubes (Sigma) according to the molar ratio of 2:1, keep the total concentration of the two at 10mg/mL, use an ultrasonic pulverizer for 2 hours and then ultrasonicate for 24 hours in a water bath to make Graphene oxide and multi-walled carbon nanotubes are homogeneously mixed.

2) The prepared graphene oxide/multi-walled carbon nanotube mixed solution was mixed with nafion (Sigma), the mass concentration of nafion was 25%, and the water bath was ultrasonically mixed for 2 hours to mix evenly.

3) Put the prepared mixed solution into a 5mL syringe, and connect the syringe with a stainless steel flat needle.

4) Place a 2cm-long thin platinum wire in a stainless steel flat needle, and push the syringe to fill the needle with the mixed solution.

5) Quickly freeze the stainless steel needle in liquid nitrogen for 1 minute.

6) Take the needle and syringe out of the liquid nitrogen and place it for one minute. After the periphery melts slightly, push it hard, and put the stick in the needle back into the liquid nitrogen to freeze.

7) Freeze-dry the frozen rods for 24 hours to obtain rod-shaped carbon airgel biological and chemical sensors as shown in Figure 2(a). The cross-section of the rod-shaped sensor is shown in Figure 2(b), so the side is a biomimetic honeycomb structure as shown in Figure 2(c), and the structure of the hole wall of the honeycomb structure is shown in Figure 2(d).

8) Change the concentration of nafion in the mixed solution to 0%, 16.7% and 9.1%, repeat steps 3 to 7, and the side views of the obtained rod electrodes are shown in Figure 3(a), (c), (d), respectively. It shows that the addition of nafion can try the carbon airgel sensor to form a stable honeycomb structure, and the size of the honeycomb aperture changes with the concentration of nafion.

9) The biomimetic honeycomb carbon airgel sensor with a nafion concentration of 25% was reduced at 600°C and 80°C in hydrazine hydrate vapor, respectively, to prepare the biomimetic honeycomb carbon airgel harmful gas sensor and biosensor.

The biomimetic honeycomb carbon airgel biological and gas sensor reduced at 600°C was connected with a digital multimeter to monitor harmful gases such as acetone vapor. The experiment found that with the increase of the concentration of acetone vapor, the bionic honeycomb carbon airgel The resistance value increases (Figure 4), the lower monitoring limit is as low as 5ppm, and the sensitivity can reach 8.5 ohm/ppm.

The prepared bionic honeycomb carbon airgel biosensor was connected to an electrochemical workstation, and the concentration of dopamine molecules in the solution was directly measured by cyclic voltammetry or differential pulse voltammetry. As shown in Figure 5(a) and (b), with the increase of the concentration of dopamine molecules, the peak value of cyclic voltammetry oxidation current and the current peak value of differential pulse voltammetry both increase linearly, and the sensitivity calculated by differential pulse Up to 8.52 x 10 ⁴ μAμM ^-1 cm ^-2 .

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that it can be described in terms of form and Various changes may be made in the details without departing from the scope of the invention defined by the claims.

Claims (3)

1. Biology and gas sensor based on carbon aerogel, it is characterized in that, comprise rod-shaped biomimetic honeycomb carbon airgel electrode and built-in metal electron collector; Described rod-shaped biomimetic honeycomb carbon airgel electrode is coated on as electron collector Around a platinum wire with a diameter of 100 microns, the electrode and the platinum wire are in contact with each other. 2. The biological and gas sensor based on biomimetic honeycomb carbon aerogel as claimed in claim 1, wherein the material constituting the biomimetic honeycomb carbon aerogel is a graphene/multi-walled carbon nanotube/nafion hybrid material. 3. claim 1 or 2 described based on the preparation method of bionic honeycomb carbon airgel biology and gas sensor, comprises the following steps: 1) Mix graphene oxide and multi-walled carbon nanotubes according to a certain ratio, and use an ultrasonic pulverizer to process them, and then use ultrasonication in a water bath to uniformly mix the obtained graphene oxide and multi-walled carbon nanotubes; 2) Mix the prepared graphene oxide/multi-walled carbon nanotube mixed solution with nafion in a certain proportion, and mix evenly in a water bath by ultrasonic; 3) Put the prepared mixed solution in a syringe, and connect the syringe with a stainless steel flat needle; 4) Place the wire electron collector in the stainless steel flat needle, and push the syringe to fill the needle with the mixed solution; 5) Place the stainless steel needle in liquid nitrogen for rapid freezing; 6) Take the needle and syringe out of the liquid nitrogen and place it for one minute. After the surrounding area melts slightly, push it hard, and put the stick in the needle back into the liquid nitrogen to freeze; 7) Freeze-dry the rod-shaped object obtained by freezing to obtain a rod-shaped biomimetic honeycomb carbon airgel electrode; 8) Change the proportion of graphene oxide/multi-walled carbon nanotubes/nafion to realize the control of electrode morphology and pore size; 9) Graphene carbon airgel biological and gas sensors were obtained by heating reduction or hydrazine vapor reduction.