METHOD FOR PREPARATION OF PLASMA-TREATED NANOFIBER-BASED HYDROGEN GAS SENSING MATERIAL

Abstract

The present disclosure provides a preparation method of a plasma-treated nanofiber-based hydrogen gas sensing material, including the following steps: (1) stirring a mixed solution of absolute ethanol, polyvinyl pyrrolidone (PVP), N, N-dimethylformamide, SnCl.sub.2.H.sub.2O, and Zn(CH.sub.3COO).sub.2.2H.sub.2O uniformly on a constant-temperature magnetic stirrer to obtain a spinning solution; (2) electrospinning the spinning solution and depositing on an aluminum foil to obtain a spinning fiber; (3) annealing the spinning fiber in a muffle furnace to obtain a hydrogen gas sensing material sample; and (4) subjecting the hydrogen gas sensing material sample to a vacuum argon plasma treatment with a Hall ion source to obtain the nanofiber-based hydrogen gas sensing material. In the method, nanofibers are prepared by electrospinning and subjected to the vacuum argon plasma treatment through the Hall ion source. The prepared sensing material has an extremely large specific surface area, and gas-sensing properties of rapid response and high sensitivity to hydrogen gas.

Claims

1. A method for preparation of a plasma-treated nanofiber-based hydrogen gas sensing material, comprising the following steps: (1) stirring a mixed solution of absolute ethanol, polyvinyl pyrrolidone (PVP), N,N-dimethylformamide (DMF), SnCl.sub.2.H.sub.2O, and Zn(CH.sub.3COO).sub.2.2H.sub.2O uniformly on a constant-temperature magnetic stirrer to obtain a spinning solution; (2) electrospinning the spinning solution and depositing on an aluminum foil to obtain a spinning fiber; (3) annealing the spinning fiber in a muffle furnace to obtain a hydrogen gas sensing material sample; and (4) subjecting the hydrogen gas sensing material sample to a vacuum argon plasma treatment with a Hall ion source to obtain the nanofiber-based hydrogen gas sensing material.

2. The method for preparation of a plasma-treated nanofiber-based hydrogen gas sensing material according to claim 1, wherein in step (1), the SnCl.sub.2.H.sub.2O and the Zn(CH.sub.3COO).sub.2.2H.sub.2O have a mass ratio of (1-1.6):(1-1.6), and the absolute ethanol, the DMF, and the PVP have a volume ratio of (1-1.5):(1-1.5):(1-1.5).

3. The method for preparation of a plasma-treated nanofiber-based hydrogen gas sensing material according to claim 2, wherein step (1) specifically comprises the following steps: mixing 0.5 g to 0.8 g of the SnCl.sub.2.H.sub.2O, 0.5 g to 0.8 g of the Zn(CH.sub.3COO).sub.2.2H.sub.2O, 5 mL to 7.5 mL of the absolute ethanol, and 5 mL to 7.5 mL of the DMF, and stirring the mixed solution on the constant-temperature magnetic stirrer at 50° C. and 300 r/min; after mixing uniformly by the stirring, adding 5 mL to 7.5 mL of the PVP to an obtained mixture, and continuing stirring at 50° C. and 300 r/m in for 6 h to mix uniformly, to obtain the spinning solution.

4. The method for preparation of a plasma-treated nanofiber-based hydrogen gas sensing material according to claim 2, wherein in step (2), a temperature is controlled at 40° C. to 60° C. and a relative humidity is controlled at 35% before the electrospinning; and the electrospinning is conducted by a flat plate winding method, with a needle as a positive electrode at a voltage range of 10 kV to 15 kV, and the aluminum foil as a negative electrode at a voltage range of 2 kV to 3 kV.

5. The method for preparation of a plasma-treated nanofiber-based hydrogen gas sensing material according to claim 2, wherein in step (3), the spinning fiber is annealed in a muffle furnace by the following three stages: a first stage of heating: heating the muffle furnace from a room temperature to 600° C. within 3 h; a second stage of maintaining a constant-temperature: maintaining the muffle furnace at 600° C. for 2 h; and a third stage of cooling: reducing a power of the muffle furnace to 0, and naturally cooling to the room temperature.

6. The method for preparation of a plasma-treated nanofiber-based hydrogen gas sensing material according to claim 2, wherein in step (4), the vacuum argon plasma treatment comprises the following steps: placing the hydrogen gas sensing material sample into a vacuum chamber; conducting vacuumization with an air pump and a molecular pump to a vacuum degree of 5×10.sup.−3 Pa, and introducing 3 sccm to 5 sccm of argon gas into the vacuum chamber to keep the vacuum degree at 1×10.sup.−2 Pa to 5×10.sup.−2 Pa; turning on the Hall ion source, adjusting an anode voltage and an anode current, starting timing, and recording a cathode voltage and a cathode current; and when the treatment is completed, turning off the Hall ion source, introducing nitrogen gas, opening the vacuum chamber, and removing the sample to complete the vacuum argon plasma treatment; wherein the vacuum argon plasma treatment is conducted at a cathode voltage of 10 V to 15 V, a cathode current of 8.0 A to 10.0 A, an anode voltage of 120 V to 150 V, and an anode current of 1.0 A to 1.9 A for 5 min to 20 min.

7. The preparation method for preparation of a plasma-treated nanofiber-based hydrogen gas sensing material according to claim 6, wherein the vacuum argon plasma treatment is conducted at the cathode voltage of 14.2 V, the cathode current of 10.0 A, the anode voltage of 150 V, and the anode current of 1.9 A.

8. The method for preparation of a plasma-treated nanofiber-based hydrogen gas sensing material according to claim 6, wherein the vacuum argon plasma treatment is conducted at the cathode voltage of 15 V, the cathode current of 8 A, the anode voltage of 145 V, and the anode current of 1.2 A for 20 min.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 shows a gas-sensing response characteristic comparison of a ZnO/SnO.sub.2 nanofiber-based sensing material prepared by a preparation method for plasma-treated nanofiber-based hydrogen gas sensing material (Example 1) and a ZnO/SnO.sub.2 nanofiber-based sensing material without plasma treatment (blank example);

[0024] FIG. 2 shows a surface topography of the ZnO/SnO.sub.2 nanofiber-based sensing material prepared by a preparation method of a plasma-treated nanofiber-based hydrogen gas sensing material (Example 1) under a field emission scanning electron microscope; and

[0025] FIG. 3 shows an X-ray diffraction (XRD) pattern of the ZnO/SnO.sub.2 nanofiber-based sensing material prepared by a preparation method of a plasma-treated nanofiber-based hydrogen gas sensing material (Example 1).

DETAILED DESCRIPTION

[0026] Blank Example: a method of preparing a plasma-treated nanofiber-based hydrogen gas sensing material included the following steps:

[0027] (1) a mixed solution of absolute ethanol, PVP, DMF, SnCl.sub.2.H.sub.2O, and Zn(CH.sub.3COO).sub.2.2H.sub.2O were stirred uniformly on a constant-temperature magnetic stirrer to obtain a spinning solution;

[0028] in step (1), the SnCl.sub.1.H.sub.2O and the Zn(CH.sub.3COO).sub.2.2H.sub.2O had a mass ratio of 1:1, and the absolute ethanol, the DMF, and the PVP had a volume ratio of 1:1:1;

[0029] specifically, step (1) included the following steps: 0.5 g of the SnCl.sub.2.H.sub.2O, 0.5 g of the Zn(CH.sub.3COO).sub.2.2H.sub.2O, 5 mL of the absolute ethanol, and 5 mL of the DMF were mixed, and stirred on the constant-temperature magnetic stirrer at 50° C. and 300 r/min; after mixing uniformly by the stirring, 5 mL of the PVP was added to an obtained mixture, and continued stirring at 50° C. and 300 r/min for 6 h to mix uniformly, to obtain the spinning solution;

[0030] (2) the spinning solution was subjected to electrospinning and deposited on an aluminum foil to obtain a spinning fiber;

[0031] in step (2), a temperature was controlled at 50° C. and a relative humidity was controlled at 35% before electrospinning; and the electrospinning was conducted by a flat plate winding method, with a needle as a positive electrode at a voltage range of 15 kV, and the aluminum foil as a negative electrode at a voltage range of 3 kV;

[0032] (3) the spinning fiber was annealed in a muffle furnace to obtain a hydrogen gas sensing material sample; and

[0033] in step (3), the spinning fiber was annealed in a muffle furnace by the following three stages:

[0034] a first stage of heating: the muffle furnace was heated from a room temperature to 600° C. within 3 h;

[0035] a second stage of maintaining a constant-temperature: the muffle furnace was maintained at 600° C. for 2 h; and

[0036] a third stage of cooling: a power of the muffle furnace was reduced to 0, and naturally cooled to the room temperature; such that the nanofiber-based hydrogen gas sensing material was obtained.

[0037] Example 1: a preparation method of a plasma-treated nanofiber-based hydrogen gas sensing material included the following steps:

[0038] (1) a mixed solution of absolute ethanol, PVP, DMF, SnCl.sub.2.H.sub.2O, and Zn(CH.sub.3COO).sub.2.2H.sub.2O were stirred uniformly on a constant-temperature magnetic stirrer to obtain a spinning solution;

[0039] in step (1), the SnCl.sub.2.H.sub.2O and the Zn(CH.sub.3COO).sub.2.2H.sub.2O had a mass ratio of 1:1, and the absolute ethanol, the DMF, and the PVP had a volume ratio of 1:1:1;

[0040] specifically, step (1) included the following steps: 0.5 g of the SnCl.sub.2.H.sub.2O, 0.5 g of the Zn(CH.sub.3COO).sub.2.2H.sub.2O, 5 mL of the absolute ethanol, and 5 mL of the DMF were mixed, and stirred on the constant-temperature magnetic stirrer at 50° C. and 300 r/min; after mixing uniformly by the stirring, 5 mL of the PVP was added to an obtained mixture, and continued stirring at 50° C. and 300 r/min for 6 h to mix uniformly, to obtain the spinning solution;

[0041] (2) the spinning solution was subjected to electrospinning and deposited on an aluminum foil to obtain a spinning fiber;

[0042] in step (2), a temperature was controlled at 50° C. and a relative humidity was controlled at 35% before the electrospinning; and the electrospinning was conducted by a flat plate winding method, with a needle as a positive electrode at a voltage range of 15 kV, and the aluminum foil as a negative electrode at a voltage range of 3 kV;

[0043] (3) the spinning fiber was annealed in a muffle furnace to obtain a hydrogen gas sensing material sample; and

[0044] in step (3), the spinning fiber was annealed in a muffle furnace by the following three stages:

[0045] a first stage of heating: the muffle furnace was heated from a room temperature to 600° C. within 3 h;

[0046] a second stage of maintaining a constant-temperature: the muffle furnace was maintained at 600° C. for 2 h; and

[0047] a third stage of cooling: a power of the muffle furnace was reduced to 0, and naturally cooled to the room temperature;

[0048] (4) an annealed hydrogen gas sensing material sample was subjected to a vacuum argon plasma treatment with a Hall ion source to obtain the nanofiber-based hydrogen gas sensing material. The nanofibers were prepared by electrospinning and subjected to the vacuum argon plasma treatment through the Hall ion source. The prepared sensing material had an extremely large specific surface area, and gas-sensing properties of rapid response and high sensitivity to hydrogen gas.

[0049] In step (4), the vacuum argon plasma treatment included the following steps: the hydrogen gas sensing material sample was placed into a vacuum chamber; vacuumization was conducted with an air pump and a molecular pump to a vacuum degree of 5×10.sup.−3 Pa, and 4 sccm of argon gas was introduced into the vacuum chamber to keep the vacuum degree at 1×10.sup.−2 Pa; the Hall ion source was turned on, an anode voltage and an anode current were adjusted, timing was started, and a cathode voltage and a cathode current were recorded; when the treatment was completed, the Hall ion source was turned off, nitrogen gas was introduced, the vacuum chamber was opened, and the sample was removed to complete the vacuum argon plasma treatment; the vacuum argon plasma treatment was conducted at a cathode voltage of 15 V, a cathode current of 8 A, an anode voltage of 145 V, and an anode current of 1.2 A for 20 min.

[0050] As shown in FIG. 1, FIG. 1 showed a gas-sensing response characteristic comparison of a ZnO/SnO.sub.2 nanofiber-based sensing material prepared by a preparation method of a plasma-treated nanofiber-based hydrogen gas sensing material (Example 1) and a ZnO/SnO.sub.2 nanofiber-based sensing material without plasma treatment (blank example); the square and circle points in FIG. 1 described the gas-sensing responses of the plasma-treated and untreated materials, respectively. It was seen that when a hydrogen concentration was 10 ppm to 500 ppm, a gas-sensing performance of the plasma-treated material was significantly better than that of the untreated material.

[0051] FIG. 2 shows a surface topography of the ZnO/SnO.sub.2 nanofiber-based sensing material prepared by a preparation method of a plasma-treated nanofiber-based hydrogen gas sensing material (Example 1) under a field emission scanning electron microscope; it was seen from the figure that the plasma-treated ZnO/SnO.sub.2 nanofiber-based sensing material has a continuous nanofiber shape, with a diameter of about 500 nm.

[0052] FIG. 3 showed an X-ray diffraction (XRD) pattern of the ZnO/SnO.sub.2 nanofiber-based sensing material prepared by a preparation method of a plasma-treated nanofiber-based hydrogen gas sensing material (Example 1); the five-pointed star and pentagon in the figure represented each diffraction peak of ZnO/SnO.sub.2, and from XRD characterization results, it was proved that the gas sensing material included ZnO/SnO.sub.2.

[0053] The objectives, technical solutions, and beneficial effects of the present disclosure are further described in detail in the above specific examples. It should be understood that the above are merely specific examples of the present invention, but are not intended to limit the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present disclosure shall fall within the protection scope of the present disclosure.