Gas sensor based on phosphorus pentoxide-doped graphene and preparation method thereof

Abstract

The present invention relates to the technical field of gas sensors, and particularly relates to a gas sensor based on phosphorus pentoxide-doped graphene and a preparation method thereof. For the gas sensor based on phosphorus pentoxide-doped graphene, phosphorus-doped graphene is prepared by using phosphorus pentoxide as a reaction source. A large number of adsorption sites are introduced on its surface due to doping, which helps to capture more gas molecules. Therefore, the gas sensor based on phosphorus atom-doped graphene has a fast response rate, is easy to reach saturation, has a fast desorption rate, good repeatability, and can operate at room temperature. In addition, the doping method proposed in the preparation method of the gas sensor based on phosphorus pentoxide-doped graphene has high controllability. The CVD system can precisely control the doping temperature, doping time, gas flow rate and ratio, so as to control the content of phosphorus elements incorporated into graphene. In addition, the CVD has sufficient internal space, simple operation, controllable process, and stable reaction, and is suitable for large-scale production in industrialization.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensors, and in particular to a gas sensor based on phosphorus pentoxide-doped graphene and a preparation method thereof. Background Art

[0002] As a new material, graphene has been widely studied and applied in various fields due to its excellent material properties. However, when graphene is applied to gas sensors, it is restricted, mainly because of its disadvantages of zero bandgap and chemical inertness, resulting in problems such as slow response speed and low sensitivity when pure graphene is used as a gas sensor. Summary of the Invention

[0003] The purpose of the present invention is to provide a gas sensor based on phosphorus pentoxide-doped graphene and a preparation method thereof, aiming to solve the problems such as slow response speed and low sensitivity when graphene is applied to gas sensors.

[0004] To achieve the above purpose, a gas sensor based on phosphorus pentoxide-doped graphene adopted by the present invention includes phosphorus pentoxide-doped graphene, two metal electrodes and a substrate. Both of the two metal electrodes are arranged on the top of the substrate, and the graphene is arranged on the top of the two metal electrodes.

[0005] Among them, the two metal electrodes are any one of Pt, Pb, Au, Ag, Ti, Ni, Al, Cu, Co.

[0006] Among them, the substrate is any one of a silicon oxide wafer, a quartz wafer, a ceramic wafer, a glass wafer.

[0007] The present invention also provides a preparation method of the above-mentioned gas sensor based on phosphorus pentoxide-doped graphene, including the following steps:

[0008] Performing photolithography on the surface of the substrate to obtain an electrode pattern;

[0009] Depositing a layer of the metal electrode on the surface of the substrate by a metal thin film deposition technique, and obtaining a patterned metal substrate structure after lift-off;

[0010] Transferring copper-based graphene to the surface of the metal substrate structure by wet etching to obtain a graphene metal substrate structure;

[0011] Performing photolithography on the graphene metal substrate structure, and removing redundant graphene by oxygen plasma to obtain a patterned graphene metal substrate structure;

[0012] Setting CVD parameters, and doping the patterned graphene metal substrate structure with phosphorus pentoxide as the source of phosphorus element.

[0013] Among them, the metal thin film deposition technology is any one of magnetron sputtering coating, thermal evaporation coating, electroplating coating, vacuum ion evaporation coating, and electron beam evaporation coating.

[0014] Among them, the method of transferring copper-based graphene to the surface of the metal substrate structure by wet etching to obtain a graphene metal substrate structure includes:

[0015] Configure an etching solution with a concentration of 0.5 - 1.5 mol / L;

[0016] Take the copper-based graphene grown by chemical vapor deposition, spin-coat a support film PMMA on its surface to obtain a PMMA graphene copper foil structure;

[0017] Place the PMMA graphene copper foil structure in the configured ammonium persulfate solution, and the copper foil and ammonium persulfate are etched away to obtain a PMMA graphene structure;

[0018] Transfer the PMMA graphene structure to the metal substrate structure with a glass slide, and then rinse it 4 - 5 times with ionized water to obtain a PMMA graphene metal substrate structure;

[0019] Place the PMMA graphene metal substrate structure in a vacuum drying cabinet and dry it at 90 °C for 45 min to make the graphene closely adhere to the metal substrate. Subsequently, remove the PMMA with acetone solution to obtain the graphene metal substrate structure.

[0020] Among them, the etching solution is a ferric chloride solution or an ammonium persulfate solution.

[0021] Among them, the method of performing photolithography on the graphene metal substrate structure to obtain a patterned graphene metal substrate structure includes:

[0022] Perform photolithography on the graphene metal substrate structure to obtain a graphene metal substrate structure with a layer of photoresist attached at a specified position;

[0023] Place the graphene metal substrate structure with a layer of photoresist attached into a plasma asher, and use oxygen plasma to etch the graphene not covered by the photoresist to complete graphene patterning, obtaining a photoresist graphene metal substrate structure;

[0024] Place the photoresist graphene metal substrate structure in acetone to remove the photoresist, obtaining the patterned graphene metal substrate structure.

[0025] Among them, the method of setting CVD parameters and doping the patterned graphene metal substrate structure with phosphorus pentoxide as the source of phosphorus includes:

[0026] Open the quartz tube of the CVD tube furnace;

[0027] Clean two quartz boats with absolute ethanol;

[0028] Put the graphene metal substrate structure into the quartz boat, and then put them together into the quartz tube;

[0029] Put 1 - 3 g of phosphorus pentoxide into another quartz boat, and then put them together into the quartz tube;

[0030] Make the inside of the quartz tube in a vacuum state through a CVD vacuum pump, and then introduce argon and hydrogen into the inside of the quartz tube, and make the ratio of argon to hydrogen between 100:10 and 100:15;

[0031] Heat the quartz tube to between 430 °C and 490 °C, and keep the constant temperature for 20 - 30 min;

[0032] After doping is completed, open the top cover of the CVD tube furnace, keep the same ratio of gas, cool down to room temperature, open the quartz tube and take out the sample, and the phosphorus doping is completed.

[0033] The beneficial effects of the present invention are as follows: For the gas sensor of phosphorus pentoxide - doped graphene, using phosphorus pentoxide as the reaction source for phosphorus - doped graphene, a large number of adsorption sites are introduced on its surface due to doping, which helps to capture more gas molecules. Therefore, the gas sensor based on phosphorus - atom - doped graphene has a fast response rate, is easy to reach saturation, has a fast desorption rate, good repeatability, and can work at room temperature; the doping method proposed in the preparation method of the gas sensor based on phosphorus pentoxide - doped graphene has high controllability, and the CVD system can precisely control the doping temperature, doping time, gas flow rate and ratio, so as to control the content of phosphorus elements incorporated into graphene. In addition, the CVD has sufficient internal space, simple operation, controllable process, stable reaction, and is suitable for large - scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0035] Figure 1 is a cross - sectional view of the gas sensor based on phosphorus pentoxide - doped graphene in the embodiment of the present invention.

[0036] Figure 2 is a step - flow chart of the preparation method of the gas sensor based on phosphorus pentoxide - doped graphene in the embodiment of the present invention.

[0037] Figure 3 It is an experimental schematic diagram of phosphorus pentoxide-doped graphene according to an embodiment of the present invention.

[0038] 1 - Graphene, 2 - Metal electrode, 3 - Substrate, 4 - Quartz tube, 5 - Phosphorus pentoxide, 6 - Graphene-metal substrate structure. Specific embodiments

[0039] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0040] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a gas sensor based on phosphorus pentoxide-doped graphene provided by an embodiment of the present invention. As Figure 1 shown, the gas sensor based on phosphorus pentoxide-doped graphene includes phosphorus pentoxide-doped graphene 1, two metal electrodes 2 and a substrate 3. Both of the two metal electrodes 2 are disposed on the top of the substrate 3, and the graphene 1 is disposed on the top of the two metal electrodes 2. The two metal electrodes 2 are any one of Pt, Pb, Au, Ag, Ti, Ni, Al, Cu, Co, and the substrate 3 is any one of a silicon oxide wafer, a quartz wafer, a ceramic wafer, and a glass wafer.

[0041] For the graphene doped with phosphorus using phosphorus pentoxide as a reaction source, a large number of adsorption sites are introduced on its surface due to doping, which helps to capture more gas molecules. Therefore, the gas sensor based on phosphorus atom-doped graphene has a fast response rate, is easy to reach saturation, has a fast desorption rate, good repeatability, and can operate at room temperature.

[0042] Please refer to Figure 2 and Figure 3 , an embodiment of the present invention also provides a preparation method of a gas sensor based on phosphorus pentoxide-doped graphene, including the following steps:

[0043] S101. Perform photolithography on the surface of the substrate 3 to obtain an electrode pattern.

[0044] Take a piece of silicon oxide as the substrate 3. The thickness of the substrate 3 is about 90 - 300.

[0045] Place the above-mentioned silicon oxide wafer in a spin coater, and drip negative photoresist evenly on the surface of the silicon oxide wafer. Set the rotation speed and time in seconds to evenly coat the negative photoresist on the surface of the silicon oxide wafer. The photoresist model is AZ5214, and the rotation speed of the spin coater is set as: low speed 450r / 10s, high speed 4000r / 40s. After spin coating, the thickness of the photoresist is approximately 1.4um.

[0046] Then heat the silicon oxide wafer with a layer of negative photoresist on a hot plate, and then perform exposure in a lithography machine. The heating time is 90s, and a URE-2000 / 35L type ultraviolet deep lithography machine is used, with an exposure time of 6s.

[0047] Perform a flood exposure again. After exposure, put the silicon oxide wafer into the developer, and then rinse it with deionized water 4 - 5 times to wash away the excess developer. The developer is of AZ300 model and needs to be developed for 40s.

[0048] After transferring the graphene, perform lithography again. Spin coat positive photoresist, use the display screen to find the corresponding position, and perform exposure. The positive photoresist model is RZJ304, and the spin coating parameters are: low speed 450r / 10s, high speed 4000r / 30s. After spin coating, the thickness of the photoresist is approximately 1.6um, and the exposure time is 2s.

[0049] Use the developer to develop the above structure, and rinse it with deionized water 4 - 5 times to wash away the excess developer. The developer model is RZX3038, and the development time is 50s.

[0050] S102. Deposit a layer of the metal electrode 2 on the surface of the substrate 3 by metal thin film deposition technology, and obtain a patterned metal substrate 3 structure after lift-off.

[0051] The metal thin film deposition technology is any one of magnetron sputtering coating, thermal evaporation coating, electroplating coating, vacuum ion evaporation coating, and electron beam evaporation coating.

[0052] S103. Transfer the copper-based graphene to the surface of the metal substrate structure by wet etching to obtain a graphene metal substrate structure.

[0053] Configure an etching solution (ferric chloride solution or ammonium persulfate solution) with a concentration of 0.5 - 1.5mol / L;

[0054] Take the copper-based graphene grown by chemical vapor deposition, and spin coat a layer of supporting film PMMA on its surface to obtain a PMMA graphene copper foil structure;

[0055] Place the PMMA graphene copper foil structure in the configured ammonium persulfate solution, and the copper foil reacts with the ammonium persulfate and is etched away to obtain a PMMA graphene structure;

[0056] Transfer the PMMA graphene structure to the metal substrate structure using a glass slide, and then rinse it 4-5 times with deionized water to obtain a PMMA graphene metal substrate structure;

[0057] Place the PMMA graphene metal substrate structure in a vacuum drying cabinet and dry it at 90 °C for 45 min to closely bond the graphene to the metal substrate 3. Subsequently, remove the PMMA with an acetone solution to obtain the graphene metal substrate structure.

[0058] S104. Perform photolithography on the graphene metal substrate structure, and use oxygen plasma to remove the excess graphene to obtain a patterned graphene metal substrate structure.

[0059] Perform photolithography on the graphene metal substrate structure to obtain a graphene metal substrate structure with a layer of photoresist attached at the specified position;

[0060] Place the graphene metal substrate structure with a layer of photoresist attached into a plasma asher, and use oxygen plasma to etch the graphene not covered by the photoresist to complete the graphene patterning and obtain a photoresist graphene metal substrate structure;

[0061] Place the photoresist graphene metal substrate structure in acetone to remove the photoresist and obtain the patterned graphene metal substrate structure.

[0062] S105. Set the CVD parameters and dope the patterned graphene metal substrate structure using phosphorus pentoxide as the source of phosphorus.

[0063] Open the quartz tube 4 of the CVD tube furnace;

[0064] Clean the two quartz boats with anhydrous alcohol;

[0065] Place the graphene metal substrate structure in the quartz boat and then place them together in the quartz tube 4;

[0066] Put 1-3 g of phosphorus pentoxide in another quartz boat and then place them together in the quartz tube 4;

[0067] Use a CVD vacuum pump to make the inside of the quartz tube 4 in a vacuum state, and then introduce argon and hydrogen into the inside of the quartz tube 4, and make the ratio of argon to hydrogen between 100:10 and 100:15;

[0068] Heat the quartz tube 4 to between 430 °C and 490 °C and keep it at a constant temperature for 20-30 min;

[0069] After the doping is completed, open the furnace hood of the CVD tube furnace, keep the same ratio of gas, cool down to room temperature, open the quartz tube and take out the sample, and the phosphorus doping is completed.

[0070] Compared with other doping methods, the doping method proposed in the preparation method of the gas sensor based on phosphorus pentoxide-doped graphene has high controllability. The CVD system can precisely control the doping temperature, doping time, gas flow rate and ratio, so as to control the content of phosphorus elements doped into graphene 1. In addition, the internal space of CVD is sufficient, the operation is simple, the process is controllable, the reaction is stable, and it is suitable for large-scale production in industrialization.

[0071] The above-disclosed is only a preferred embodiment of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Those of ordinary skill in the art can understand all or part of the processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the invention.

Claims

1. A preparation method of a gas sensor based on phosphorus pentoxide-doped graphene, characterized in that, It includes the following steps: Perform photolithography on the substrate surface to obtain an electrode pattern; Deposit a metal electrode on the substrate surface by metal thin film deposition technology, and obtain a patterned metal substrate structure after lift-off; Transfer copper-based graphene to the surface of the metal substrate structure by wet etching to obtain a graphene metal substrate structure; Perform photolithography on the graphene metal substrate structure, and use oxygen plasma to remove excess graphene to obtain a patterned graphene metal substrate structure; Set CVD parameters, and dope the patterned graphene metal substrate structure using phosphorus pentoxide as the source of elemental phosphorus; The setting of CVD parameters and doping the patterned graphene metal substrate structure using phosphorus pentoxide as the source of elemental phosphorus includes: Open the quartz tube of the CVD tube furnace; Clean two quartz boats with absolute ethanol; Place the graphene metal substrate structure in the quartz boat, and then place them together into the quartz tube; Put 1-3 g of phosphorus pentoxide in another quartz boat, and then place them together into the quartz tube; Make the inside of the quartz tube in a vacuum state through a CVD vacuum pump, and then introduce argon and hydrogen into the inside of the quartz tube, and make the ratio of argon to hydrogen between 100:10 and 100:15; Heat the quartz tube to between 430°C and 490°C, and keep it at a constant temperature for 20-30 min; After doping is completed, open the top cover of the CVD tube furnace, keep the same proportion of gas, cool down to room temperature, open the quartz tube and take out the sample, and phosphorus doping is completed.

2. The preparation method of the gas sensor based on phosphorus pentoxide-doped graphene according to claim 1, wherein The metal thin film deposition technology is any one of magnetron sputtering coating, thermal evaporation coating, electroplating coating, vacuum ion evaporation coating, and electron beam evaporation coating.

3. The preparation method of the gas sensor based on phosphorus pentoxide-doped graphene according to claim 2, wherein, The transfer of copper-based graphene to the surface of the metal substrate structure by wet etching to obtain a graphene metal substrate structure includes: Prepare an etching solution with a concentration of 0.5-1.5 mol / L; Take the copper-based graphene grown by chemical vapor deposition, and spin-coat a support film PMMA on its surface to obtain a PMMA graphene copper foil structure; Place the PMMA graphene copper foil structure in the prepared ammonium persulfate solution, and the copper foil reacts with ammonium persulfate and is etched away to obtain a PMMA graphene structure; Transfer the PMMA graphene structure to the metal substrate structure with a glass slide, and then rinse it with ionized water 4-5 times to obtain a PMMA graphene metal substrate structure; Place the PMMA graphene metal substrate structure in a vacuum drying cabinet, dry it at 90°C for 45 min to make the graphene closely adhere to the metal substrate, and then remove PMMA with acetone solution to obtain the graphene metal substrate structure.

4. The preparation method of the gas sensor based on phosphorus pentoxide-doped graphene according to claim 3, wherein The etching solution is ferric chloride solution, ammonium persulfate solution.

5. The preparation method of the gas sensor based on phosphorus pentoxide-doped graphene according to claim 4, characterized in that, The photolithography of the graphene metal substrate structure to obtain a patterned graphene metal substrate structure includes: Lithographically pattern the graphene-metal substrate structure to obtain a graphene-metal substrate structure with a layer of photoresist attached at a specified position; Place the graphene-metal substrate structure with a layer of photoresist attached into a plasma asher, and etch the graphene not covered by the photoresist with oxygen plasma to complete graphene patterning, obtaining a photoresist-graphene-metal substrate structure; Place the photoresist-graphene-metal substrate structure in acetone to remove the photoresist, obtaining the patterned graphene-metal substrate structure.

6. A gas sensor based on phosphorus pentoxide-doped graphene, which adopts the preparation method of the gas sensor based on phosphorus pentoxide-doped graphene as claimed in claim 5, wherein, it includes phosphorus pentoxide-doped graphene, two metal electrodes and a substrate. Both of the two metal electrodes are arranged on the top of the substrate, and the graphene is arranged on the top of the two metal electrodes.

7. The gas sensor based on phosphorus pentoxide-doped graphene as claimed in claim 6, wherein, the two metal electrodes are any one of Pt, Pb, Au, Ag, Ti, Ni, Al, Cu, Co.

8. The gas sensor based on phosphorus pentoxide-doped graphene as claimed in claim 7, wherein, the substrate is any one of a silicon oxide wafer, a quartz wafer, a ceramic wafer, a glass wafer.

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