A gas sensor for dual-mode detection of multiple VOCs and its preparation method

Abstract

The present invention belongs to the technical field of gas sensors, and specifically relates to a gas sensor that can be used for dual-modal detection of multiple VOCs and a preparation method thereof. The present invention constructs a hexagonal close-packed single-layer SiO2 microsphere array on the non-test electrode part of a flat electrode and deposits an Au film or Ag, then transfers the single-layer PS microsphere array immersed in a precursor solution to an Au or Ag / SiO2 array and a test electrode, and anneals to sacrifice the single-layer PS microsphere array, thereby obtaining a Ni-SnO2 / Au or Ag / SiO2 double-layer array electrode. After the double-layer array electrode is assembled with a heater, the gas sensor can be used for dual-modal detection of multiple VOCs. In the prepared sensor, the eddy current generated in the Ni-SnO2 bowl of the double-layer array slows down the flow of VOCs and transports them to the gaps between the lower Ni-SnO2 / Au or Ag / SiO2 array units. These array units have both SERS activity and electrical sensitivity, which improves the sensor's high sensitivity response to multiple VOCs gases and has important application value in dual-modal monitoring sensors.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas sensors, and in particular relates to a gas sensor that can be used for dual-mode detection of multiple VOCs and a preparation method thereof. Background Art

[0002] VOCs (Volatile Organic Compounds) refer to organic compounds that have a high saturated vapor pressure (greater than 13.33 Pa), a low boiling point, a small molecular weight, and are easily volatile at room temperature under standard conditions. VOCs such as benzene and formaldehyde vapors produced in industrial production processes, automobile exhaust and household products can cause health hazards to the respiratory tract, liver, kidneys and central nervous system. Efficient monitoring of VOCs in human activity spaces is crucial for early warning and timely intervention, reducing safety risks and maintaining public health. At present, a single VOCs detection method is difficult to meet the needs of highly sensitive, highly selective, real-time and portable monitoring.

[0003] Existing technology achieves dual-modal monitoring by combining SERS technology and semiconductor sensing technology, which has been proven to be an effective means to achieve efficient and real-time monitoring of VOCs. Specifically, VOCs exposure causes the continuously running electrical sensor to produce a positive response, triggering SERS recognition.

[0004] For example, by designing and using ultrathin oxide-coated plasmonic metal nanoparticles (NPs), dual-modal monitoring of VOCs molecules such as thiols can be achieved. The oxide coating can interact with and capture target gas molecules, generating a conductivity response, while the plasmonic metal NPs have strong SERS activity. However, the performance of the detection device in this technology (high LoD at the level of tens of ppm) and the manufacturing reproducibility of the device cannot meet the requirements of practical applications. Therefore, the challenges of careful design of key devices and development of batch manufacturing to achieve higher performance and strong device reproducibility still need to be overcome. Summary of the Invention

[0005] One of the objectives of the present invention is to provide a method for preparing a gas sensor that can be used for dual-modal detection of multiple VOCs. This method forms a sensitive material in situ on a flat electrode. The sensitive material is a SiO2 array coated with a double layer of Ni-SnO2, Au or Ag, and the upper surface of the coating layer has a bowl-shaped pit array. This sensitive material can improve the sensor's high sensitivity response to multiple VOCs gases and has important application value in dual-modal monitoring sensors.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing a gas sensor that can be used for dual-mode detection of multiple VOCs, comprising the following steps:

[0007] 1) obtaining a flat sheet electrode comprising a flat flexible substrate and two strip-shaped test electrodes disposed on opposite ends of one surface of the flexible substrate;

[0008] The flat electrode was cleaned and hydrophilized, a mask was placed on the surface of two strip test electrodes, and a hexagonally close-packed single-layer SiO2 microsphere array was constructed on the mask and the surface of the flexible substrate on which the mask was placed using a gas / liquid interface self-assembly method.

[0009] Depositing a layer of gold or silver film on the surface of a single-layer SiO2 microsphere array, and then removing the mask on the two strip electrodes to form an Au or Ag / SiO2 array;

[0010] 2) forming a tightly packed monolayer PS microsphere array on a glass substrate via a gas / liquid interface self-assembly method, and then transferring the microspheres to a precursor solution containing 1.0-10.0 wt% SnCl4 and 0.1-0.5 wt% Ni(NO3)2 in water, where the microspheres float on the liquid surface after natural drying;

[0011] The Au or Ag / SiO2 array in step 1) is used to fish out the monolayer PS microsphere array in the precursor solution. The monolayer PS microsphere array is laid flat on the Au or Ag / SiO2 array until it dries. The salt in the precursor solution precipitates to fill the gap between the Au or Ag / SiO2 array and the monolayer PS microsphere array, thereby obtaining a PS microsphere / Au or Ag / SiO2 array.

[0012] The PS microsphere / Au or Ag / SiO2 array is subjected to an annealing process to sacrifice a single-layer PS microsphere array and convert the salt in the precursor solution into Ni-SnO2. After natural drying, a SiO2 array with a surface coated by a double layer of Ni-SnO2 and Au or a double layer of Ni-SnO2 and Ag is in situ formed on a flat electrode, and the upper surface of the coating layer has a bowl-shaped pit array, which is recorded as a Ni-SnO2 / Au or Ag / SiO2 double-layer array electrode;

[0013] 3) A heater is placed on the lower surface of the Ni-SnO2 / Au or Ag / SiO2 double-layer array electrode, and two strip test electrodes are connected to the current collector to produce a gas sensor that can be used for dual-modal detection of multiple VOCs.

[0014] As a further improvement to the above-mentioned preparation method of the gas sensor for dual-modal detection of multiple VOCs:

[0015] Preferably, the flexible substrate in the flat electrode is made of quartz or silicon, the side length or diameter of the flat electrode is 0.2-2 cm, and the width of the strip test electrode on the flexible substrate is 0.03-0.3 cm.

[0016] Preferably, the specific operation of cleaning and hydrophilizing the flat electrode is: cleaning the flat electrode with ethanol, acetone and deionized water in sequence, and then treating it with ozone for 5-10 minutes.

[0017] Preferably, the particle size of the SiO2 microspheres in the single-layer SiO2 microsphere array is 50-500 nm.

[0018] Preferably, the thickness of the gold film or silver film is 30-150 nm.

[0019] Preferably, the particle size of the PS microspheres in the single-layer PS microsphere array is 80-500 nm.

[0020] Preferably, the annealing process is an oxygen plasma annealing process.

[0021] Preferably, the specific operation of the oxygen plasma annealing process is to place the sensor in an oxygen plasma cleaning machine for 20-60 minutes in an oxygen atmosphere.

[0022] A second object of the present invention is to provide a gas sensor for dual-modal detection of multiple VOCs, which is prepared by the method for preparing a gas sensor for dual-modal detection of multiple VOCs as described in any one of the above.

[0023] As a further improvement of the above-mentioned gas sensor that can be used for dual-modal detection of multiple VOCs:

[0024] Preferably, the gas sensor is placed in a detection chamber for multiple VOCs gases, and a heater is turned on to heat the temperature to 150-300° C. to monitor VOCs efficiently and in real time.

[0025] The beneficial effects of the present invention compared to the prior art are:

[0026] 1) The present invention provides a method for preparing a gas sensor that can be used for dual-modal detection of multiple VOCs. The method comprises constructing a hexagonally close-packed single-layer SiO2 microsphere array on the non-test electrode portion of a flat electrode and depositing an Au film or an Ag film to form an Au or Ag / SiO2 array. The single-layer PS microsphere array, which has been immersed in a precursor solution, is then transferred to the Au or Ag / SiO2 array and the test electrode. After annealing the sacrificial single-layer PS microsphere array, a sensitive layer is prepared on the flat electrode. The electrode is assembled with a heater to form a gas sensor. The sensitive layer structure consists of a double-layer ordered array structure: the surface layer is a semiconductor oxide sensitive film with an electrical response and has an ultra-thin, ordered, porous structure; the bottom layer is a noble metal (gold, silver) nanopillar array rich in SERS hotspots, which is also an ordered array in structure.

[0027] 2) The present invention combines a flat electrode with a double-layer sensitive layer with a heater and current collector to produce a sensor. The current collector is used to collect the electrical sensing signal, and the heater is used to control the operating temperature. The resulting gas sensor exhibits dual-mode response performance, both electrical and SERS spectroscopy. Eddy currents generated in the Ni-SnO2 bowls of the upper array slow the flow of VOCs and transport them to the gaps between the lower Ni-SnO2 / Au or Ag / SiO2 array elements. These array elements exhibit both SERS activity and electrical sensitivity, enhancing the sensor's high sensitivity to various VOC gases and possessing significant application value in dual-mode monitoring sensors. Specifically, when target gas molecules are present in the environment, they first contact the surface oxide sensitive layer, generating a rapid electrical response and exhibiting real-time response characteristics. Subsequently, SERS spectroscopy analysis is performed, and the target molecules are accurately identified through the SERS spectrum. This achieves both real-time response and accurate identification of target VOC molecules, and the large-area consistency of the sensitive elements ensures signal repeatability and reproducibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart for preparing the Ni-SnO2 / Au or Ag / SiO2 double-layer array electrode of the present invention.

[0029] Figure 2 This is a typical SEM morphology of the Ni-SnO2 / Au or Ag / SiO2 double-layer array electrode prepared in Example 1. The upper figure and its inset show top view images at different magnifications, and the lower figure shows a cross-sectional image.

[0030] Figure 3 The results of the dual-mode monitoring performance test of the sensor prepared in Example 1 for styrene vapor are shown in Figure 1. The working temperature is 250°C, and the sensor resistance and SERS response (1001cm -1 The peak intensity at (A) varies with styrene concentration, where (A) is electrical sensing and (B) is SERS sensing.

[0031] Figure 4 The resistance change and Raman spectrum of the Ni-SnO2 / Au / SiO2 double-layer array sensor prepared in Example 1 in response to styrene vapor at a concentration of 200 ppm at a heating temperature of 250°C.

[0032] Figure 5 These are SEM images of the Ni-SnO2 / Au / SiO2 double-layer array electrode prepared using PS microspheres of different particle sizes in Example 2, where (A) is 500nm, (B) is 300nm, (C) is 200nm, and (D) is 120nm.

[0033] Figure 6The gas sensor prepared by the 300 nm microsphere array in Example 2 was used to perform electrical and SERS monitoring of 100 ppm of toluene, dodecanethiol, and ethanol at a heating temperature of 150°C.

[0034] Figure 7 The SEM images of the Ni-SnO2 / Au / SiO2 double-layer array electrodes with different bowl wall thicknesses prepared by using precursor solutions of different concentrations in Example 3 are shown in FIG. 4+ Concentration 0.3M, (B)Sn 4+ Concentration 0.2M, (C)Sn 4+ Concentration 0.1M, (D)Sn 4+ Concentration 0.05M.

[0035] Figure 8 The gas sensor prepared in Example 3 using an aqueous solution of 1.75wt% SnCl4 and 0.1wt% Ni(NO3)2 as a precursor solution was used to perform electrical and SERS monitoring of three VOC gases, namely, 100ppm benzaldehyde, xylene, and nitrobenzene, at a heating temperature of 250°C. DETAILED DESCRIPTION

[0036] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] This embodiment provides a method for preparing a gas sensor that can be used for dual-mode detection of multiple VOCs, which specifically includes the following steps:

[0039] 1) Prepare a flat electrode comprising a flat flexible substrate and two strip-shaped test electrodes disposed on opposite ends of one surface of the flexible substrate. The flat electrode is made of a quartz sheet and measures 5 mm by 5 mm. The strip test electrodes on the flexible substrate are 0.1 cm wide.

[0040] The flat electrode was cleaned and hydrophilized, and a mask was placed on the surface of the two strip test electrodes. Using the air / liquid interface self-assembly method, a hexagonal close-packed single-layer SiO2 microsphere array with a particle size of 150 nm was constructed on the mask and the surface of the flexible substrate on which the mask was placed.

[0041] A layer of Au film (110 nm thick) was deposited on the surface of the single-layer SiO2 microsphere array using a Q150Rplus sputtering coater (Quorum). The masks on the two strip electrodes were then removed to form an Au / SiO2 array.

[0042] 2) Forming a tightly packed monolayer PS microsphere array (500 nm in diameter) on a glass substrate via a gas / liquid interface self-assembly method. After natural drying, the array was transferred to a precursor solution containing 7.0 wt% SnCl₄ and 0.2 wt% Ni(NO₃)₂ in water and allowed to float on the surface for 5 minutes.

[0043] The Au / SiO2 array in step 1) is used to fish out the monolayer PS microsphere array in the precursor solution. The monolayer PS microsphere array is laid flat on the Au / SiO2 array and dried naturally. The salt in the precursor solution precipitates and fills the gap between the Au / SiO2 array and the monolayer PS microsphere array, thereby obtaining a PS microsphere / Au / SiO2 array.

[0044] The PS microsphere / Au / SiO2 array was irradiated in an oxygen plasma cleaner for 40 minutes in an oxygen atmosphere. The single-layer PS microsphere array was sacrificed and the salt was converted into Ni-SnO2. After natural drying, a SiO2 array with a double layer of Ni-SnO2 and Au coated on the surface was formed in situ on the flat electrode. The upper surface of the coating layer had a bowl-shaped pit array, which was recorded as a Ni-SnO2 / Au / SiO2 double-layer array electrode.

[0045] 3) A heater is set on the lower surface of the Ni-SnO2 / Au / SiO2 double-layer array electrode, and two strip test electrodes are connected to the collector to obtain a gas sensor that can be used for dual-modal detection of multiple VOCs.

[0046] Figure 1 This is a flow chart for preparing the Ni-SnO2 / Au or Ag / SiO2 double-layer array electrode of the present invention.

[0047] Figure 2 This is a typical SEM morphology image of the Ni-SnO2 / Au / SiO2 double-layer array electrode prepared in Example 1. It can be seen that the upper array is a hexagonal close-packed bowl-shaped array with a period of about 500nm and a bowl sidewall thickness of 20nm, and the lower array is an Au nanocolumn array with a period of about 150nm.

[0048] Figure 3 The sensor is tested for dual-mode monitoring performance of styrene vapor at an operating temperature of 250°C. The sensor resistance and SERS response (1001cm -1The peak intensity at (A) changes with styrene concentration. (A) Electrical sensing; (B) SERS sensing. The figures show that the dual-mode gas sensor has a detection limit as low as 50 ppb, demonstrating excellent monitoring performance.

[0049] The Ni-SnO2 / Au / SiO2 double-layer array sensor prepared in Example 1 was placed in an environment containing styrene vapor at a concentration of 200 ppm. The sensor temperature was heated to 250°C by the heating function of the heater. The gas sensitive tester and Raman spectrometer were turned on to record the resistance change and Raman spectrum of the sensor. When the target gas appeared in the environment, the resistance change of the sensor and the corresponding Raman spectrum were observed, as shown in FIG. Figure 4 The left figure shows the electrical sensing signal (upper) and the time-resolved SERS signal (lower), and the right figure shows the SERS spectra obtained at different times. Figure 4 It can be seen that the sensor has strong and synchronous electrical and SERS response signals to styrene gas, with an electrical response time of 1.5 seconds, a SERS response time of 10 seconds, an electrical recovery time of 7 seconds, and a SERS recovery time of 25 seconds, indicating that real-time monitoring and accurate identification of target molecules can be achieved.

[0050] Example 2

[0051] This embodiment provides a method for preparing a gas sensor that can be used for dual-mode detection of multiple VOCs, which specifically includes the following steps:

[0052] 1) preparing an Au / SiO2 array by referring to step 1) of Example 1;

[0053] 2) Forming a tightly packed monolayer PS microsphere array (PS microsphere particle size: 500 nm, 300 nm, 200 nm, and 120 nm) on a glass substrate via a gas / liquid interface self-assembly method. After natural drying, the array was transferred to a precursor solution containing 7.0 wt% SnCl4 and 0.2 wt% Ni(NO3)2 in water, where it was allowed to float on the liquid surface for 5 minutes.

[0054] The Au / SiO2 array in step 1) is used to fish out the monolayer PS microsphere array in the precursor solution. The monolayer PS microsphere array is laid flat on the Au / SiO2 array and dried naturally. The salt in the precursor solution precipitates and fills the gap between the Au / SiO2 array and the monolayer PS microsphere array, thereby obtaining a PS microsphere / Au / SiO2 array.

[0055] The PS microsphere / Au / SiO2 array was placed in an oxygen plasma cleaner and irradiated for 40 minutes in an oxygen atmosphere. The single-layer PS microsphere array was sacrificed and the salt was converted into Ni-SnO2. After natural drying, a SiO2 array with a surface coated with a double layer of Ni-SnO2 and Au was formed in situ on the flat electrode. The upper surface of the coating layer had an array of bowl-shaped pits of different sizes, which was recorded as a Ni-SnO2 / Au / SiO2 double-layer array electrode. Figure 4 ;

[0056] 3) A heater is set on the lower surface of the Ni-SnO2 / Au / SiO2 double-layer array electrode, and two strip test electrodes are connected to the collector to obtain a gas sensor that can be used for dual-modal detection of multiple VOCs.

[0057] Example 2 The SEM images of the Ni-SnO2 / Au / SiO2 double-layer array electrode prepared using PS microspheres of different particle sizes are shown in the following order: Figure 5 (A)-(D) shown, where (A) 500nm, (B) 300nm, (C) 200nm, (D) 120nm. Figure 5 It can be seen that Ni-SnO2 / Au / SiO2 double-layer array electrodes with different bowl-shaped pit sizes can be prepared by using PS microspheres with different particle sizes.

[0058] The gas sensor prepared by the 300 nm microsphere array in Example 2 was used to perform electrical and SERS detection of toluene, dodecanethiol, and ethanol. The heating temperature was 150°C. The results were as follows: Figure 6 As shown, the gas sensor exhibits good electrical real-time response and SERS spectroscopy recognition performance.

[0059] Example 3

[0060] This embodiment provides a method for preparing a gas sensor that can be used for dual-mode detection of multiple VOCs, which specifically includes the following steps:

[0061] 1) preparing an Au / SiO2 array by referring to step 1) of Example 1;

[0062] 2) A tightly packed monolayer PS microsphere array (PS microsphere particle size of 500 nm) was formed on a glass substrate by a gas / liquid interface self-assembly method. After natural drying, the microspheres were transferred to a precursor solution containing, in sequence, 10.0 wt% SnCl4 and 0.3 wt% Ni(NO3)2 in water, 7.0 wt% SnCl4 and 0.2 wt% Ni(NO3)2 in water, 3.5 wt% SnCl4 and 0.1 wt% Ni(NO3)2 in water, and 1.75 wt% SnCl4 and 0.1 wt% Ni(NO3)2 in water;

[0063] The Au / SiO2 array in step 1) is used to fish out the monolayer PS microsphere array in the precursor solution. The monolayer PS microsphere array is laid flat on the Au / SiO2 array and dried naturally. The salt in the precursor solution precipitates and fills the gap between the Au / SiO2 array and the monolayer PS microsphere array, thereby obtaining a PS microsphere / Au / SiO2 array.

[0064] The PS microsphere / Au / SiO2 array was irradiated in an oxygen plasma cleaner for 40 minutes in an oxygen atmosphere. The single-layer PS microsphere array was sacrificed and the salt was converted into Ni-SnO2. After natural drying, a SiO2 array with a double layer of Ni-SnO2 and Au coated on the surface was formed in situ on the flat electrode. The upper surface of the coating layer had an array of bowl-shaped pits of different sizes, which was recorded as a Ni-SnO2 / Au / SiO2 double-layer array electrode.

[0065] 3) A heater is set on the lower surface of the Ni-SnO2 / Au / SiO2 double-layer array electrode, and two strip test electrodes are connected to the collector to obtain a gas sensor that can be used for dual-modal detection of multiple VOCs.

[0066] The SEM images of Ni-SnO2 / Au / SiO2 double-layer array electrodes with different bowl wall thicknesses prepared by using precursor solutions of different concentrations are shown in FIG. Figure 7 As shown, (A) 10.0wt% SnCl4, (B) 7.0wt% SnCl4, (C) 3.5wt% SnCl4, (D) 1.75wt% SnCl4. Figure 7 It can be seen that the Sn content in the precursor solution can be controlled by 4+ Salt and Ni 2+ concentration to achieve the wall thickness of the bowl-shaped pits in the Ni-SnO2 / Au / SiO2 double-layer array electrode.

[0067] The gas sensor prepared by using the aqueous solution of 1.75wt% SnCl4 and 0.1wt% Ni(NO3)2 as the precursor solution in Example 3 was used to perform electrical and SERS detection on benzaldehyde, xylene, and nitrobenzene gases with a concentration of 100ppm. The heating temperature was 250℃. The results are as follows: Figure 8 As shown, the above-mentioned gas sensor exhibits good electrical real-time response and SERS spectroscopy recognition performance.

[0068] Those skilled in the art will appreciate that the foregoing descriptions are merely specific embodiments of the present invention, and not exhaustive. It should be noted that numerous variations and modifications are possible for those skilled in the art, and all such variations and modifications that do not exceed the scope of the claims should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a gas sensor for dual-mode detection of multiple VOCs, characterized in that: The steps include: 1) A flat sheet electrode is prepared, comprising a flat flexible substrate and two strip-shaped test electrodes disposed on opposite ends of one surface of the flexible substrate; The flat electrode was cleaned and hydrophilized, a mask was placed on the surface of two strip test electrodes, and a hexagonally close-packed single-layer SiO2 microsphere array was constructed on the mask and the surface of the flexible substrate on which the mask was placed using a gas / liquid interface self-assembly method. Depositing a layer of gold or silver film on the surface of a single-layer SiO2 microsphere array, and then removing the mask on the two strip electrodes to form an Au or Ag / SiO2 array; 2) A densely packed monolayer PS microsphere array was formed on a glass substrate via a gas / liquid interface self-assembly method. After natural drying, the microspheres were transferred to a precursor solution containing 1.0-10.0 wt% SnCl4 and 0.1-0.5 wt% Ni(NO3)2 in water and floated on the liquid surface. The monolayer PS microsphere array in the precursor solution is fished out using the Au or Ag / SiO2 array from step 1), and the monolayer PS microsphere array is laid flat on the Au or Ag / SiO2 array until it dries. Salt in the precursor solution precipitates to fill the gap between the Au or Ag / SiO2 array and the monolayer PS microsphere array, thereby obtaining a PS microsphere / Au or Ag / SiO2 array. The PS microsphere / Au or Ag / SiO2 array is subjected to an annealing process to sacrifice a single-layer PS microsphere array and convert the salt in the precursor solution into Ni-SnO2. After natural drying, a SiO2 array with a surface coated by a double layer of Ni-SnO2 and Au or a double layer of Ni-SnO2 and Ag is in situ formed on a flat electrode, and the upper surface of the coating layer has a bowl-shaped pit array, which is recorded as a Ni-SnO2 / Au or Ag / SiO2 double-layer array electrode; 3) A heater is placed on the lower surface of the Ni-SnO2 / Au or Ag / SiO2 double-layer array electrode, and two strip test electrodes are connected to the collector to produce a gas sensor that can be used for dual-modal detection of multiple VOCs.

2. The method for preparing a gas sensor for dual-mode detection of multiple VOCs according to claim 1, characterized in that: The flexible substrate in the flat electrode is made of quartz or silicon, the side length or diameter of the flat electrode is 0.2-2 cm, and the width of the strip test electrode on the flexible substrate is 0.03-0.3 cm.

3. The method for preparing a gas sensor for dual-mode detection of multiple VOCs according to claim 1, characterized in that: The specific operation of cleaning and hydrophilic treatment of the flat electrode is as follows: the flat electrode is cleaned with ethanol, acetone and deionized water in sequence, and then treated with ozone for 5-10 minutes.

4. The method for preparing a gas sensor for dual-mode detection of multiple VOCs according to claim 1, characterized in that: The particle size of SiO2 microspheres in the single-layer SiO2 microsphere array is 50-500 nm.

5. The method for preparing a gas sensor for dual-mode detection of multiple VOCs according to claim 1, characterized in that: The thickness of the gold or silver film is 30-150 nm.

6. The method for preparing a gas sensor for dual-mode detection of multiple VOCs according to claim 1, characterized in that: The particle size of PS microspheres in the monolayer PS microsphere array is 80-500 nm.

7. The method for preparing a gas sensor for dual-mode detection of multiple VOCs according to claim 1, characterized in that: The annealing process is an oxygen plasma annealing process.

8. The method for preparing a gas sensor for dual-mode detection of multiple VOCs according to claim 7, characterized in that: The specific operation of the oxygen plasma annealing process is to place the PS microsphere / Au or Ag / SiO2 array in an oxygen plasma cleaning machine and irradiate it for 20-60 minutes in an oxygen atmosphere.

9. A gas sensor for dual-modal detection of multiple VOCs, prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the gas sensor for dual-modal detection of multiple VOCs according to claim 9 in dual-modal detection of multiple VOCs, characterized in that: The gas sensor is placed in a detection chamber for various VOCs gases, and the heater is turned on to heat it to 150-300°C to monitor VOCs efficiently and in real time.

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