A composite sensitized quartz tuning fork for acetylene detection, a preparation method thereof and an acetylene detection device

Abstract

This invention discloses a composite sensitized quartz tuning fork for acetylene detection, its preparation method, and an acetylene detection device, relating to the field of gas detection. The composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitizing layer. The quartz tuning fork includes two resonant arms, and the composite sensitizing layer is disposed on the opposing inner surfaces of the two resonant arms. The composite sensitizing layer comprises an rGO substrate layer and Pd nanoclusters. In this application, a composite sensitizing layer is provided on the quartz tuning fork. The rGO substrate layer provides a large-area adsorption interface and a stable mechanical coupling channel for acetylene molecules, while the low-coverage Pd nanoclusters form a large number of spatially uniformly distributed active adsorption sites. The two elements form a synergistic sensitization effect, resulting in high adsorption efficiency for acetylene. Its resonant frequency exhibits a stable and monotonic drift trend with increasing acetylene concentration. By measuring this resonant frequency drift in real time, quantitative detection of acetylene gas concentration can be achieved.

Description

Technical Field

[0001] This invention relates to the field of gas detection, and more particularly to a composite sensitized quartz tuning fork for acetylene detection, its preparation method, and an acetylene detection device. Background Technology

[0002] A quartz tuning fork (QTF) is a miniature resonator that utilizes the piezoelectric effect of quartz crystal to achieve highly stable mechanical resonance. It offers advantages such as stable resonant frequency, high quality factor, low temperature drift, simple structure, and low cost. The standard 32.768 kHz quartz tuning fork has been widely used in timing and frequency reference applications, demonstrating mature and reliable mechanical and electrical properties and ease of integration with various electronic measurement circuits. Based on these advantages, quartz tuning forks have been increasingly introduced into the field of gas sensing in recent years, serving as highly sensitive transducers for weak gas-structure interactions. Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) is a typical gas detection scheme. This technology modulates a laser to irradiate the gas to be measured, causing gas molecules to absorb light energy and generate periodic photoacoustic waves. The high quality factor resonance response of the quartz tuning fork to these sound waves is then used to convert the acoustic signal into an electrical signal, thereby achieving gas concentration measurement. QEPAS technology has been widely used in the detection of gases such as methane (CH4) and carbon monoxide (CO), which have large infrared absorption cross sections and high vibration-translational energy relaxation efficiency.

[0003] However, acetylene gas has a significantly different molecular structure from saturated hydrocarbons such as methane. Acetylene molecules have a linear structure and strong C≡C triple bonds, and its vibrational energy level distribution and energy relaxation characteristics differ from common saturated hydrocarbons. Under normal temperature conditions, the efficiency of energy absorption and conversion into thermal or acoustic energy is relatively low. This characteristic means that in photoacoustic detection schemes, the effective photoacoustic signal amplitude generated by acetylene is usually weaker than that of gases such as methane, thus placing higher demands on the system's sensitivity and stability.

[0004] Furthermore, QEPAS technology itself relies on a stable, narrow-linewidth laser, precise optical path alignment, and strict matching between the modulation frequency and the resonant frequency of the quartz tuning fork, resulting in a complex system structure and high cost. In applications targeting acetylene detection, the aforementioned optical and acoustic coupling requirements further amplify the system design complexity, hindering its widespread application in industrial settings or portable devices.

[0005] Therefore, although QEPAS technology has demonstrated good performance in the detection of gases such as methane, its technical approach is not the optimal choice for acetylene gas detection. Given the limited photoacoustic conversion efficiency of acetylene molecules under room temperature conditions and the high complexity of the detection system, there is an urgent need to explore a novel technical solution that does not rely on the photoacoustic effect and can directly utilize the changes in the resonant characteristics of a quartz tuning fork to achieve acetylene detection. Summary of the Invention

[0006] This invention provides a composite sensitized quartz tuning fork for acetylene detection, its preparation method, and an acetylene detection device. By utilizing the synergistic sensitization structure formed by rGO and Pd nanoclusters in the composite sensitization layer, the sensitivity and stability of acetylene gas detection are improved without significantly altering the inherent mechanical structure and resonant modes of the quartz tuning fork.

[0007] To address the aforementioned technical problems, one objective of this invention is to provide a composite sensitized quartz tuning fork for acetylene detection, comprising a quartz tuning fork and a composite sensitization layer. The quartz tuning fork includes two parallel and spaced-apart resonant arms, and the composite sensitization layer is disposed on the opposing inner surfaces of the two resonant arms. The composite sensitization layer comprises an rGO substrate layer and Pd nanoclusters arranged sequentially along the direction away from the resonant arms.

[0008] This application incorporates a composite sensitization layer on the surface of a resonant vibrating arm. rGO, with its two-dimensional sheet structure and large specific surface area, contains abundant defect sites and π-conjugated electronic structures, providing numerous adsorption sites for acetylene molecules. This allows acetylene molecules to form a stable physical or weak chemisorption interface on the sensitization layer surface. Simultaneously, the rGO sheet structure provides a stable loading substrate for Pd nanoclusters. When Pd nanoclusters are dispersed on the rGO surface with low coverage, they form a large number of spatially uniformly distributed active adsorption sites. rGO provides a large-area adsorption interface and stable mechanical coupling channels, resulting in a synergistic sensitization effect. This significantly improves the adsorption efficiency of acetylene molecules on the sensitization layer surface. The combined effect of molecular adsorption, interfacial coupling, and mass loading enhances the sensitivity and stability of acetylene gas detection.

[0009] Without significantly altering the inherent mechanical structure and resonant modes of the quartz tuning fork, the adsorption amount of acetylene molecules on the surface of the composite sensitization layer changes with the concentration of acetylene in the test gas, thus causing a change in the equivalent mass of the sensitization layer. Due to the stable mechanical coupling between the composite sensitization layer and the quartz tuning fork arm, this mass change directly affects the mechanical resonance system of the quartz tuning fork, altering its equivalent vibrating mass and manifesting as a measurable drift in the resonant frequency. This frequency drift can be acquired in real time via electrical means, enabling highly sensitive and stable detection of acetylene gas. The entire detection process requires no laser, light source, or optical modulation unit; the system structure is simple, easy to integrate, and suitable for miniaturization and engineering applications.

[0010] In some embodiments, the thickness of the rGO substrate layer is 50-200 nm.

[0011] This application preferably controls the thickness of the rGO substrate layer within the above-mentioned range. When the thickness of the rGO substrate layer is less than 50 nm, the resulting sheet structure is thin and lacks continuity, with limited effective specific surface area and the number of defect sites per unit area. This results in fewer acetylene adsorption sites, which is not conducive to forming a stable gas adsorption interface, thereby reducing the capture capacity and detection sensitivity of acetylene molecules. When the thickness of the rGO substrate layer is greater than 200 nm, although the number of adsorption sites increases further, the excessively thick rGO layer will significantly increase the mass loading of the composite sensitization layer and weaken its mechanical coupling efficiency with the quartz tuning fork arm. This makes it difficult for the mass change caused by gas adsorption to be effectively transmitted to the vibration system of the quartz tuning fork. It may also lead to excessive resonant frequency shift and a decrease in quality factor, affecting detection stability.

[0012] Therefore, controlling the thickness of the rGO substrate layer within the range of 50-200 nm can ensure a high specific surface area and abundant adsorption sites while maintaining good structural continuity and mechanical flexibility of the rGO substrate layer and forming a stable coupling relationship with the quartz tuning fork arm. This achieves a better balance between gas adsorption capacity, mass loading effect and resonance performance, thereby improving the sensitivity and stability of acetylene detection.

[0013] In some embodiments, the rGO substrate layer has a coverage of 50%-100% on the inner surface of the resonant arm, preferably 60%-70%; in a preferred embodiment, the rGO substrate layer extends from the free end of the resonant arm toward the connecting base and covers an area of ​​2 / 3 of the total length of the resonant arm.

[0014] In some embodiments, the Pd nanoclusters have a coverage of 0.5%-5% on the surface of the rGO substrate.

[0015] Because Pd metal exhibits strong surface interaction with molecules containing unsaturated carbon-carbon bonds, when Pd nanoclusters are dispersed on the surface of the rGO substrate at the aforementioned low coverage, the rGO sheet structure provides a stable loading substrate for the Pd nanoclusters and effectively inhibits nanoparticle aggregation, allowing the Pd nanoclusters to maintain high dispersion and effective surface area. Simultaneously, the C≡C triple bond in acetylene molecules can interact with the d-orbital electrons on the Pd surface, thereby forming a strong chemisorption or quasi-chemisorption state on the Pd nanocluster surface. When Pd nanoclusters are dispersed on the rGO surface at the aforementioned low coverage, a large number of spatially uniformly distributed active adsorption sites can be formed, significantly improving the adsorption efficiency of acetylene molecules on the sensitized layer surface.

[0016] In some embodiments, the average particle size of the Pd nanoclusters is 2-10 nm.

[0017] This application preferably controls the average particle size of Pd nanoclusters within the aforementioned range. When the average particle size of Pd nanoclusters is less than 2 nm, the nanoclusters are too small, resulting in unstable surface atomic coordination and a tendency to migrate and aggregate. This leads to a reduction in active sites during use, affecting the structural stability of the sensitized layer and the repeatability of detection. When the average particle size of Pd nanoclusters is greater than 10 nm, their specific surface area decreases significantly, reducing the number of surface active sites available per unit area. Simultaneously, the increased spacing between nanoparticles hinders the formation of uniformly distributed gas adsorption active centers, thereby reducing the adsorption efficiency for acetylene molecules. Therefore, controlling the average particle size of Pd nanoclusters within the range of 2–10 nm ensures a high specific surface area and abundant active sites while improving the dispersion stability of the nanoclusters, thus achieving efficient adsorption of acetylene molecules.

[0018] In some embodiments, the equivalent height of the Pd nanoclusters is 1-5 nm.

[0019] This application preferably controls the equivalent height of the Pd nanoclusters within the aforementioned range. When the equivalent height of the Pd nanoclusters is less than 1 nm, their structure is close to an ultrathin atomic layer or a discontinuous distribution state, making it difficult to form a stable three-dimensional nanostructure. The number of active sites is limited, and structural rearrangement or deactivation is prone to occur. When the equivalent height of the Pd nanoclusters is greater than 5 nm, the nanoclusters tend to be bulk particles, their specific surface area decreases, and the overall mass loading of the composite sensitization layer increases, which is not conducive to maintaining the stable resonance characteristics of the quartz tuning fork. Therefore, controlling the equivalent height of the Pd nanoclusters within the range of 1-5 nm can ensure the stability of the nanocluster structure while taking into account both high surface activity and low mass loading, thereby improving the sensitivity and stability of acetylene detection.

[0020] In some embodiments, the composite sensitized layer accounts for 0.5%-1% of the mass fraction of the quartz tuning fork.

[0021] By controlling the mass fraction of the composite sensitized layer in the quartz tuning fork within the above-mentioned range, this application can ensure that the resonant frequency change rate is less than 1% and the quality factor decreases by no more than 20%, thus keeping the mass loading and acoustic performance of each sensitized quartz tuning fork within a controllable range.

[0022] In some embodiments, the mass of the quartz tuning fork is 60-90 μg.

[0023] In some embodiments, the quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork.

[0024] To address the aforementioned technical problems, a second objective of this invention is to provide a method for preparing a composite sensitized quartz tuning fork for acetylene detection, comprising the following steps: (1) The rGO dispersion was drop-coated onto the corresponding surface of the resonant arm and dried to form the rGO substrate layer; (2) H2PdC was dropped onto the rGO substrate. l4 The solution was mixed with an equal volume of NaBH4 solution for in-situ reduction to generate Pd nanoclusters. After rinsing and drying, a composite sensitized quartz tuning fork was obtained.

[0025] In some embodiments, in step (1), the concentration of rGO in the rGO dispersion is 0.1-0.5 mmol / L.

[0026] In some embodiments, in step (1), the rGO dispersion is drop-coated onto the corresponding surface of the resonant arm at a rate of 0.1-0.5 μL / drop.

[0027] In some embodiments, in step (1), the rGO dispersion is pre-treated with ultrasonic dispersion.

[0028] In some embodiments, in step (1), the ultrasonic dispersion time of the rGO dispersion is 10-60 min.

[0029] In some embodiments, in step (1), the drying temperature is 50-60 °C and the drying time is 10-30 min.

[0030] In some implementations, in step (2), the H2PdC l4 H2PdC in solution l4 The concentration is 0.05-0.5 mmol / L.

[0031] In some embodiments, in step (2), the concentration of NaBH4 in the NaBH4 solution is 0.5-2 mmol / L.

[0032] To address the aforementioned technical problems, a third objective of this invention is to provide an acetylene detection device, comprising a composite sensitized quartz tuning fork.

[0033] In some embodiments, the acetylene detection device further includes a computer device, a function generator, a first preamplifier, a second preamplifier, and a lock-in amplifier. The electrode pins of the composite sensitized quartz tuning fork are connected to the first and second preamplifiers. The first preamplifier is connected to the function generator, and the second preamplifier is connected to the lock-in amplifier. Both the function generator and the lock-in amplifier are connected to the computer device.

[0034] When the two resonant arms of the composite sensitized quartz tuning fork are placed in the test gas environment, the function generator, under the control of a computer, outputs a preset electrical excitation signal. This signal is then applied to the electrode pins of the composite sensitized quartz tuning fork after amplitude matching by a first preamplifier, exciting it to undergo mechanical resonance near its natural resonant frequency. As a piezoelectric transducer, the composite sensitized quartz tuning fork generates a piezoelectric response current signal corresponding to its vibration state on its electrode pins under mechanical resonance. This piezoelectric response signal is amplified transimpedance by a second preamplifier and then sent to a lock-in amplifier for synchronous demodulation. The lock-in amplifier uses the electrical excitation signal or its synchronization signal output by the function generator as a reference signal to perform phase-sensitive detection on the amplified piezoelectric response signal, thereby obtaining the resonant response characteristics of the composite sensitized quartz tuning fork under different excitation frequency conditions.

[0035] Compared with the prior art, the present invention has the following beneficial effects: 1. This application sets a composite sensitization layer on the surface of the resonant arm of a quartz tuning fork. The rGO substrate layer contains abundant defect sites and π-conjugated electronic structures, which can provide a large-area adsorption interface and a stable mechanical coupling channel for acetylene molecules. The low-coverage Pd nanoclusters on the surface can form a large number of spatially uniformly distributed active adsorption sites. The two form a synergistic sensitization effect, thereby significantly improving the adsorption efficiency of acetylene molecules on the surface of the sensitization layer. Its resonant frequency can show a stable and monotonic drift trend with the increase of acetylene concentration, showing good acetylene gas selectivity.

[0036] 2. The composite sensitizing layer of the quartz tuning fork in this application accounts for 0.5%-1% of the mass of the quartz tuning fork, which can ensure that the resonant frequency change rate is less than 1% and the quality factor decreases by no more than 20%. This keeps the mass loading and acoustic performance of each sensitized quartz tuning fork within a controllable range. The composite sensitizing layer will not have an unacceptable negative impact on the resonant frequency and quality factor of the quartz tuning fork, thus improving the sensitivity and stability of acetylene gas detection. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of a composite sensitized quartz tuning fork for acetylene detection in an embodiment of this application; Figure 2 This is a schematic diagram of an acetylene detection device according to this application; Figure 3 The graphs showing the relationship between the resonant frequency of the composite sensitized quartz tuning fork and the concentration of acetylene gas in Examples 1 and 3 of this application are shown. Figure 4 This is a statistical chart showing the resonant frequency drift of the composite sensitized quartz tuning fork in Examples 1-3 of this application as a function of methane / acetylene concentration; Figure 5This is a statistical chart showing the resonant frequency drift of the composite sensitized quartz tuning fork in Examples 4-6 of this application as a function of methane / acetylene concentration; Figure 6 This is a statistical chart showing the resonant frequency drift of the composite sensitized quartz tuning fork in Examples 7-9 of this application as a function of methane / acetylene concentration; Figure 7 Statistical charts showing the resonant frequency drift of the composite sensitized quartz tuning fork in Examples 10-11 and Comparative Example 1 of this application as a function of methane / acetylene concentration; Figure 8 Statistical charts showing the resonant frequency drift of the composite sensitized quartz tuning forks in Comparative Examples 2-4 of this application as a function of methane / acetylene concentration; The reference numerals in the accompanying drawings are as follows: 1. Computer equipment; 2. Composite sensitized quartz tuning fork; 20. Connecting base; 21. Resonant vibrating arm; 22. rGO substrate layer; 23. Pd nanocluster; 24. Electrode pin; 3. Function generator; 4. First preamplifier; 5. Second preamplifier; 6. Lock-in amplifier. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0040] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0041] As used in this article: In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0042] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0043] In the description of this invention, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", etc., indicating orientation or positional relationship are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0044] To further illustrate the present invention, the following detailed description is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention. Unless otherwise specified, the raw materials used in the following embodiments and comparative examples are all commercially available, and the same raw materials were used in parallel experiments.

[0045] Example 1 A composite sensitized quartz tuning fork for acetylene detection, such as Figure 1 As shown, it includes a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode pins and two parallel and spaced resonant arms. One end of the two resonant arms is fixedly connected to the connecting base, and the two electrode pins are fixedly disposed on the side of the connecting base opposite to the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms. The mass of the composite sensitization layer is 0.5% of the effective mass of the quartz tuning fork. The composite sensitization layer includes a reduced graphene oxide (rGO) substrate and Pd nanoclusters arranged sequentially along the direction away from the resonant arms. The rGO substrate extends from the free end of the resonant arm toward the connecting base and covers a region of 2 / 3 of the total length of the resonant arm. That is, the coverage of the rGO substrate on the inner surface of the resonant arm is about 67%. The thickness of the rGO substrate is 100 nm. The coverage of the Pd nanoclusters on the surface of the rGO substrate is 3%. The average particle size of the Pd nanoclusters is 5 nm. The equivalent height of the Pd nanoclusters on the surface of the rGO substrate is 3 nm.

[0046] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the relative inner surfaces of the two resonant arms at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. (3) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the rGO basal layer. l4 The solution was prepared by in-situ reduction of sparse Pd nanoclusters by adding an equal volume of 1 mmol / L NaBH4 aqueous solution, followed by rinsing with deionized water and drying at a temperature below 60 °C to finally obtain the composite sensitized quartz tuning fork.

[0047] Example 2 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the thickness of the rGO substrate layer is different. Specifically, the composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly located on the side of the connecting base facing away from the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms. The mass of the composite sensitization layer is 0.3% of the effective mass of the quartz tuning fork. The composite sensitization layer includes a reduced graphene oxide (rGO) substrate and Pd nanoclusters arranged sequentially along the direction away from the resonant arms. The rGO substrate extends from the free end of the resonant arm toward the connecting base and covers a region of 2 / 3 of the total length of the resonant arm. That is, the coverage of the rGO substrate on the inner surface of the resonant arm is about 67%. The thickness of the rGO substrate is 50 nm. The coverage of the Pd nanoclusters on the surface of the rGO substrate is 3%. The average particle size of the Pd nanoclusters is 5 nm. The equivalent height of the Pd nanoclusters on the surface of the rGO substrate is 3 nm.

[0048] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the relative inner surfaces of the two resonant arms at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. (3) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the rGO basal layer. l4 The solution was prepared by in-situ reduction of sparse Pd nanoclusters by adding an equal volume of 1 mmol / L NaBH4 aqueous solution, followed by rinsing with deionized water and drying at a temperature below 60 °C to finally obtain the composite sensitized quartz tuning fork.

[0049] Example 3 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the thickness of the rGO substrate layer is different. Specifically, the composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly located on the side of the connecting base facing away from the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms. The mass of the composite sensitization layer is 0.9% of the effective mass of the quartz tuning fork. The composite sensitization layer includes a reduced graphene oxide (rGO) substrate and Pd nanoclusters arranged sequentially along the direction away from the resonant arms. The rGO substrate extends from the free end of the resonant arm toward the connecting base and covers a region of 2 / 3 of the total length of the resonant arm. That is, the coverage of the rGO substrate on the inner surface of the resonant arm is about 67%. The thickness of the rGO substrate is 200 nm. The coverage of the Pd nanoclusters on the surface of the rGO substrate is 3%. The average particle size of the Pd nanoclusters is 5 nm. The equivalent height of the Pd nanoclusters on the surface of the rGO substrate is 3 nm.

[0050] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the relative inner surfaces of the two resonant arms at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. (3) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the rGO basal layer. l4 The solution was prepared by in-situ reduction of sparse Pd nanoclusters by adding an equal volume of 1 mmol / L NaBH4 aqueous solution, followed by rinsing with deionized water and drying at a temperature below 60 °C to finally obtain the composite sensitized quartz tuning fork.

[0051] Example 4 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the average particle size and equivalent height of the Pd nanoclusters are different. Specifically, the composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly disposed on the side of the connecting base facing away from the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms. The mass of the composite sensitization layer is about 0.45% of the effective mass of the quartz tuning fork. The composite sensitization layer includes a reduced graphene oxide (rGO) substrate and Pd nanoclusters arranged sequentially along the direction away from the resonant arms. The rGO substrate extends from the free end of the resonant arm toward the connecting base and covers a region of 2 / 3 of the total length of the resonant arm. That is, the coverage of the rGO substrate on the inner surface of the resonant arm is about 67%. The thickness of the rGO substrate is 100 nm. The coverage of the Pd nanoclusters on the surface of the rGO substrate is 3%. The average particle size of the Pd nanoclusters is 2 nm. The equivalent height of the Pd nanoclusters on the surface of the rGO substrate is 1 nm.

[0052] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the relative inner surfaces of the two resonant arms at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. (3) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the rGO basal layer. l4The solution was prepared by in-situ reduction of sparse Pd nanoclusters by adding an equal volume of 1 mmol / L NaBH4 aqueous solution, followed by rinsing with deionized water and drying at a temperature below 60 °C to finally obtain the composite sensitized quartz tuning fork.

[0053] Example 5 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the average particle size and equivalent height of the Pd nanoclusters are different. Specifically, the composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly disposed on the side of the connecting base facing away from the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms. The mass of the composite sensitization layer is about 0.6% of the effective mass of the quartz tuning fork. The composite sensitization layer includes a reduced graphene oxide (rGO) substrate and Pd nanoclusters arranged sequentially along the direction away from the resonant arms. The rGO substrate extends from the free end of the resonant arm toward the connecting base and covers a region of 2 / 3 of the total length of the resonant arm. That is, the coverage of the rGO substrate on the inner surface of the resonant arm is about 67%. The thickness of the rGO substrate is 100 nm. The coverage of the Pd nanoclusters on the surface of the rGO substrate is 3%. The average particle size of the Pd nanoclusters is 10 nm, and the equivalent height of the Pd nanoclusters on the surface of the rGO substrate is 5 nm.

[0054] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the relative inner surfaces of the two resonant arms at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. (3) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the rGO basal layer. l4 The solution was prepared by in-situ reduction of sparse Pd nanoclusters by adding an equal volume of 1 mmol / L NaBH4 aqueous solution, followed by rinsing with deionized water and drying at a temperature below 60 °C to finally obtain the composite sensitized quartz tuning fork.

[0055] Example 6 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the Pd nanoclusters have a different surface coverage on the rGO substrate. Specifically, the composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly located on the side of the connecting base facing away from the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms. The mass of the composite sensitization layer is approximately 0.42% of the effective mass of the quartz tuning fork. The composite sensitization layer includes a reduced graphene oxide (rGO) substrate and Pd nanoclusters arranged sequentially along the direction away from the resonant arms. The rGO substrate extends from the free end of the resonant arm toward the connecting base and covers a region of 2 / 3 of the total length of the resonant arm. That is, the coverage of the rGO substrate on the inner surface of the resonant arm is approximately 67%. The thickness of the rGO substrate is 100 nm. The coverage of the Pd nanoclusters on the surface of the rGO substrate is 0.5%. The average particle size of the Pd nanoclusters is 5 nm, and the equivalent height of the Pd nanoclusters on the surface of the rGO substrate is 3 nm.

[0056] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the relative inner surfaces of the two resonant arms at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. (3) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the rGO basal layer. l4 The solution was prepared by in-situ reduction of sparse Pd nanoclusters by adding an equal volume of 1 mmol / L NaBH4 aqueous solution, followed by rinsing with deionized water and drying at a temperature below 60 °C to finally obtain the composite sensitized quartz tuning fork.

[0057] Example 7 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the Pd nanoclusters have a different surface coverage on the rGO substrate. Specifically, the composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly located on the side of the connecting base facing away from the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms. The mass of the composite sensitization layer is approximately 0.58% of the effective mass of the quartz tuning fork. The composite sensitization layer includes a reduced graphene oxide (rGO) substrate and Pd nanoclusters arranged sequentially along the direction away from the resonant arms. The rGO substrate extends from the free end of the resonant arm toward the connecting base and covers a region of 2 / 3 of the total length of the resonant arm. That is, the coverage of the rGO substrate on the inner surface of the resonant arm is approximately 67%. The thickness of the rGO substrate is 100 nm. The coverage of the Pd nanoclusters on the surface of the rGO substrate is 5%. The average particle size of the Pd nanoclusters is 5 nm, and the equivalent height of the Pd nanoclusters on the surface of the rGO substrate is 3 nm.

[0058] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the relative inner surfaces of the two resonant arms at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. (3) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the rGO basal layer. l4 The solution was prepared by in-situ reduction of sparse Pd nanoclusters by adding an equal volume of 1 mmol / L NaBH4 aqueous solution, followed by rinsing with deionized water and drying at a temperature below 60 °C to finally obtain the composite sensitized quartz tuning fork.

[0059] Example 8 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the Pd nanoclusters have a different surface coverage on the rGO substrate. Specifically, the composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly located on the side of the connecting base facing away from the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms. The mass of the composite sensitization layer is about 0.65% of the effective mass of the quartz tuning fork. The composite sensitization layer includes a reduced graphene oxide (rGO) substrate and Pd nanoclusters arranged sequentially along the direction away from the resonant arms. The rGO substrate extends from the free end of the resonant arm toward the connecting base and covers a region of 2 / 3 of the total length of the resonant arm. That is, the coverage of the rGO substrate on the inner surface of the resonant arm is about 67%. The thickness of the rGO substrate is 100 nm. The coverage of the Pd nanoclusters on the surface of the rGO substrate is 7%. The average particle size of the Pd nanoclusters is 5 nm. The equivalent height of the Pd nanoclusters on the surface of the rGO substrate is 3 nm.

[0060] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the relative inner surfaces of the two resonant arms at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. (3) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the rGO basal layer. l4 The solution was prepared by in-situ reduction of sparse Pd nanoclusters by adding an equal volume of 1 mmol / L NaBH4 aqueous solution, followed by rinsing with deionized water and drying at a temperature below 60 °C to finally obtain the composite sensitized quartz tuning fork.

[0061] Example 9 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the mass fraction of the composite sensitization layer relative to the effective mass of the quartz tuning fork is different. Specifically, the composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly located on the side of the connecting base facing away from the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms. The mass of the composite sensitization layer is 0.2% of the effective mass of the quartz tuning fork. The composite sensitization layer includes a reduced graphene oxide (rGO) substrate and Pd nanoclusters arranged sequentially along the direction away from the resonant arms. The rGO substrate extends from the free end of the resonant arm toward the connecting base and covers a region of 2 / 3 of the total length of the resonant arm. That is, the coverage of the rGO substrate on the inner surface of the resonant arm is about 67%. The thickness of the rGO substrate is 50 nm. The coverage of the Pd nanoclusters on the surface of the rGO substrate is 0.5%. The average particle size of the Pd nanoclusters is 2 nm, and the equivalent height of the Pd nanoclusters on the surface of the rGO substrate is 1 nm.

[0062] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the relative inner surfaces of the two resonant arms at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. (3) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the rGO basal layer. l4 The solution was prepared by in-situ reduction of sparse Pd nanoclusters by adding an equal volume of 1 mmol / L NaBH4 aqueous solution, followed by rinsing with deionized water and drying at a temperature below 60 °C to finally obtain the composite sensitized quartz tuning fork.

[0063] Example 10 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the mass fraction of the composite sensitization layer relative to the effective mass of the quartz tuning fork is different. Specifically, the composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly located on the side of the connecting base facing away from the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms. The mass of the composite sensitization layer is 1% of the effective mass of the quartz tuning fork. The composite sensitization layer includes a reduced graphene oxide (rGO) substrate and Pd nanoclusters arranged sequentially along the direction away from the resonant arms. The rGO substrate extends from the free end of the resonant arm toward the connecting base and covers a region of 2 / 3 of the total length of the resonant arm. That is, the coverage of the rGO substrate on the inner surface of the resonant arm is about 67%. The thickness of the rGO substrate is 200 nm. The coverage of the Pd nanoclusters on the surface of the rGO substrate is 5%. The average particle size of the Pd nanoclusters is 5 nm. The equivalent height of the Pd nanoclusters on the surface of the rGO substrate is 3 nm.

[0064] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the relative inner surfaces of the two resonant arms at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. (3) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the rGO basal layer. l4 The solution was prepared by in-situ reduction of sparse Pd nanoclusters by adding an equal volume of 1 mmol / L NaBH4 aqueous solution, followed by rinsing with deionized water and drying at a temperature below 60 °C to finally obtain the composite sensitized quartz tuning fork.

[0065] Example 11 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the mass fraction of the composite sensitization layer relative to the effective mass of the quartz tuning fork is different. Specifically, the composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly located on the side of the connecting base facing away from the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms. The mass of the composite sensitization layer is 1.5% of the effective mass of the quartz tuning fork. The composite sensitization layer includes a reduced graphene oxide (rGO) substrate and Pd nanoclusters arranged sequentially along the direction away from the resonant arms. The rGO substrate extends from the free end of the resonant arm toward the connecting base and covers a region of 2 / 3 of the total length of the resonant arm. That is, the coverage of the rGO substrate on the inner surface of the resonant arm is about 67%. The thickness of the rGO substrate is 250 nm. The coverage of the Pd nanoclusters on the surface of the rGO substrate is 7%. The average particle size of the Pd nanoclusters is 12 nm. The equivalent height of the Pd nanoclusters on the surface of the rGO substrate is 6 nm.

[0066] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the relative inner surfaces of the two resonant arms at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. (3) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the rGO basal layer. l4 The solution was prepared by in-situ reduction of sparse Pd nanoclusters by adding an equal volume of 1 mmol / L NaBH4 aqueous solution, followed by rinsing with deionized water and drying at a temperature below 60 °C to finally obtain the composite sensitized quartz tuning fork.

[0067] Comparative Example 1 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the composite sensitization layer does not contain Pd nanoclusters. Specifically, the composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly located on the side of the connecting base facing away from the resonant arms. The composite sensitization layer is disposed on the opposing inner surfaces of the two resonant arms. The mass of the composite sensitization layer is approximately 0.4% of the effective mass of the quartz tuning fork. The composite sensitization layer includes a reduced graphene oxide (rGO) substrate layer. The rGO substrate layer extends from the free end of the resonant arm towards the connecting base, covering a region of 2 / 3 of the total length of the resonant arm, i.e., the coverage of the rGO substrate layer on the inner surface of the resonant arm is approximately 67%, and the thickness of the rGO substrate layer is 100 nm.

[0068] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the relative inner surfaces of the two resonant arms at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. Finally, the composite sensitive quartz tuning fork was prepared.

[0069] Comparative Example 2 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the composite sensitization layer does not have an rGO substrate layer. Specifically, the composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly located on the side of the connecting base facing away from the resonant arms. The composite sensitization layer is disposed on the opposing inner surfaces of the two resonant arms. The mass of the composite sensitization layer is 0.1% of the effective mass of the quartz tuning fork. The composite sensitization layer includes Pd nanoclusters located in a region extending from the free end of the resonant arm towards the connecting base to a distance of 2 / 3 of the total length of the resonant arm. The Pd nanoclusters have a 2% coverage rate on the inner surface of the resonant arm, an average particle size of 5 nm, and an equivalent height of 3 nm on the surface of the resonant arm.

[0070] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the inner surfaces of the two resonant arms. l4 The solution was prepared by in-situ reduction of sparse Pd nanoclusters by adding an equal volume of 1 mmol / L NaBH4 aqueous solution, followed by rinsing with deionized water and drying at a temperature below 60 °C to finally obtain the composite sensitized quartz tuning fork.

[0071] Comparative Example 3 A quartz tuning fork for acetylene detection differs from Example 1 in that the resonant arms do not have a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly located on the side of the connecting base facing away from the two resonant arms.

[0072] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks by cleaning the surface of the resonant arm with isopropanol and drying it to obtain quartz tuning forks.

[0073] Comparative Example 4 A composite sensitized quartz tuning fork for acetylene detection differs from Example 1 in that the composite sensitization layer comprises Pd nanoclusters and a reduced graphene oxide (rGO) substrate layer sequentially arranged along the direction away from the resonant arms. Specifically, the composite sensitized quartz tuning fork includes a quartz tuning fork and a composite sensitization layer. The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork with an effective mass of 75 μg. It includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly disposed on the side of the connecting base opposite to the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms. The mass of the composite sensitization layer is 0.5% of the effective mass of the quartz tuning fork. The composite sensitization layer includes Pd nanoclusters and reduced graphene oxide (rGO) substrate layer arranged sequentially along the direction away from the resonant arms. The Pd nanoclusters are located in the region extending from the free end of the resonant arms toward the connecting base to 2 / 3 of the total length of the resonant arms. The coverage of the Pd nanoclusters on the inner surface of the resonant arms is 2%. The average particle size of the Pd nanoclusters is 5 nm. The equivalent height of the Pd nanoclusters on the inner surface of the resonant arms is 3 nm. The rGO substrate layer is located in the region extending from the free end of the resonant arms toward the connecting base to 2 / 3 of the total length of the resonant arms. That is, the rGO substrate layer occupies 67% of the inner surface area of ​​the resonant arms. The thickness of the rGO substrate layer is 100 nm.

[0074] The preparation method of the composite sensitized quartz tuning fork for acetylene detection includes the following steps: (1) Prepare commercial quartz tuning forks, clean the surface of the resonant arm with isopropanol and dry it; (2) Add a small amount of H2PdC at a concentration of 0.3 mmol / L to the inner surfaces of the two resonant arms. l4 The solution was prepared by adding an equal volume of 1 mmol / L NaBH4 aqueous solution for in-situ reduction to generate sparse Pd nanoclusters, followed by rinsing with deionized water and drying at a temperature below 60 °C. (3) The reduced graphene oxide (rGO) dispersion with a concentration of 0.5 mg / mL was ultrasonically treated for 30 min to achieve uniform dispersion. The solvent of the rGO dispersion was deionized water. The rGO dispersion was drop-coated onto the inner surface of the resonant vibrating arm at a rate of about 0.3 μL / drop. After natural drying, it was dried at a low temperature of 55 °C for 15 min. The thickness was adjusted by controlling the drop volume to form the rGO substrate layer. Finally, the composite sensitive quartz tuning fork was prepared.

[0075] Table 1 - Parameter settings of the composite sensitization layer in the composite sensitized quartz tuning fork of this application The composite sensitized quartz tuning fork prepared in this application embodiment can also be used to assemble an acetylene detection device, such as... Figure 2 As shown, the acetylene detection device specifically includes a computer, a composite sensitized quartz tuning fork, a function generator, a first preamplifier, a second preamplifier, and a lock-in amplifier.

[0076] The composite sensitized quartz tuning fork comprises a quartz tuning fork and a composite sensitization layer. The quartz tuning fork includes a connecting base, two electrode leads, and two parallel and spaced-apart resonant arms. One end of each resonant arm is fixedly connected to the connecting base, and the two electrode leads are fixedly disposed on the side of the connecting base facing away from the two resonant arms. The composite sensitization layer is disposed on the opposite inner surfaces of the two resonant arms and comprises a reduced graphene oxide (rGO) substrate layer and Pd nanoclusters arranged sequentially along the direction away from the resonant arms.

[0077] The electrode pins of the composite sensitive quartz tuning fork are connected to a first preamplifier and a second preamplifier. The first preamplifier is connected to a function generator, and the second preamplifier is connected to a lock-in amplifier. Both the function generator and the lock-in amplifier are connected to computer equipment.

[0078] The two resonant arms of the composite sensitized quartz tuning fork can be placed in the acetylene gas environment to be tested. The function generator outputs a preset electrical excitation signal under the control of the computer equipment, and after amplitude matching by the first preamplifier, it is applied to the electrode pins of the composite sensitized quartz tuning fork to excite it to undergo mechanical resonance near its natural resonant frequency.

[0079] The composite sensitive quartz tuning fork, as a piezoelectric transducer, generates a piezoelectric response current signal on its electrode pins in a mechanical resonance state, which corresponds to the vibration state. The piezoelectric response signal is amplified by a second preamplifier and then sent to a lock-in amplifier for synchronous demodulation.

[0080] The lock-in amplifier uses the electrical excitation signal or its synchronization signal output from the function generator as a reference signal to perform phase-sensitive detection on the amplified piezoelectric response signal, thereby obtaining the resonant response characteristics of the composite sensitive quartz tuning fork under different excitation frequencies. By sweeping the frequency, the resonant frequency position of the composite sensitive quartz tuning fork can be determined continuously or periodically.

[0081] In a further embodiment, the function generator performs continuous or periodic frequency sweeps on the composite sensitized quartz tuning fork within a preset frequency range to obtain its complete frequency response curve and determine the resonant frequency f and quality factor Q under the current gas environment. This frequency sweep process can be continuously performed during the detection process to continuously or periodically acquire and process the minute drift of the resonant frequency.

[0082] In a further embodiment, the computer device can dynamically adjust the excitation frequency of the function generator based on the phase or amplitude response of the lock-in amplifier output, so as to achieve the tracking measurement of the resonant frequency.

[0083] Performance testing 1. Surface coverage of Pd nanoclusters: Surface coverage θ is defined as the ratio of the actual projected area of ​​Pd nanoclusters on the surface of the loaded material to the total area of ​​the statistical region, and its expression is: ; in, This is the sum of the equivalent projected areas of all Pd nanoclusters. To determine the total area of ​​the field of view of the loaded material, this application acquires surface images of the loaded material's field of view using a scanning electron microscope (SEM), and performs threshold segmentation and particle identification using image processing software such as ImageJ to obtain the average diameter d of each Pd nanocluster. Based on this, the coverage can be further expressed as: In the formula, N is the total amount of Pd nanoclusters, and the test results are shown in Table 1.

[0084] 2. Quality Testing of the Composite Sensitized Layer: Establish a quantitative relationship between the quality of the composite sensitized layer and the change in the resonant frequency of the quartz tuning fork. Equivalently, the commercial quartz tuning fork is treated as a single-degree-of-freedom resonant system in the inverted fundamental mode, and its intrinsic resonant frequency is determined. With equivalent stiffness and effective quality satisfy: ; When a mass is loaded onto the surface of the resonant vibrating arm When the composite sensitizer layer is used, the resonant frequency becomes: ; A first-order expansion of this expression yields the relative rate of change of the resonant frequency and the quality of the composite sensitizer layer. Relationship: , ; It can be seen that the relative decrease in resonant frequency is approximately equal to the mass of the composite sensitizer layer. Relative to effective mass Half of the total mass. Therefore, by measuring the change in resonant frequency before and after loading the composite sensitizer layer, the equivalent mass loading of the composite sensitizer layer can be deduced. The following calculation formula must be satisfied: The mass fraction of the composite sensitized layer in the quartz tuning fork and the rate of change of the resonant frequency after the composite sensitized layer is loaded can be further calculated. The test results are shown in Table 1.

[0085] 3. Quality Factor Change Rate: Commercially available quartz tuning forks and the composite sensitized quartz tuning forks prepared in the examples and comparative examples were respectively installed in the test circuit, and the resonant response was tested under room temperature, normal pressure, and high-purity nitrogen atmosphere. During the test, a function generator performed frequency sweep excitation near the resonant frequency of the quartz tuning fork, and a lock-in amplifier synchronously acquired the amplitude-frequency response curve of the quartz tuning fork, and recorded the resonant frequency of each sample. and half-power bandwidth The quality factor of a quartz tuning fork Calculate using the following formula: ; The quality factor of commercial quartz tuning forks was measured respectively. Quality factor of composite sensitive quartz tuning fork Then, the rate of change of the quality factor is calculated using the following formula: ; Because the composite sensitization layer introduces additional mass and damping, the quality factor of a composite sensitized quartz tuning fork is typically lower than that of a commercial quartz tuning fork; therefore, the rate of change of the quality factor is generally negative. The influence of the composite sensitization layer parameters on the resonant performance of the quartz tuning fork in different embodiments and comparative examples can be evaluated using the above method. The test results are shown in Table 1.

[0086] 4. Relationship between resonant frequency drift and acetylene gas concentration: The composite sensitized quartz tuning forks prepared in the examples and comparative examples were installed in a sealed gas testing chamber, with both arms fully exposed to the gas environment to be tested. During the test, high-purity nitrogen (purity ≥99.999%) was used as the carrier gas and reference gas, and an acetylene standard gas mixture with a volume fraction of 1000 ppm was used as the concentration source. The acetylene standard gas was dynamically diluted with high-purity nitrogen using a mass flow controller to obtain acetylene test gases of different concentrations.

[0087] Before the test, high-purity nitrogen was continuously introduced into the test chamber to purge the system for 10 minutes to eliminate residual gas and stabilize the baseline. Then, the composite sensitized quartz tuning fork was excited by a function generator, and its reference resonant frequency f0 was measured under pure nitrogen conditions. Following this, acetylene mixtures with concentrations of 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, and 1000 ppm were sequentially introduced into the test chamber. At each concentration, the gas flow rate was kept stable, and the test was allowed to proceed for approximately 3 minutes to allow the gas concentration to stabilize within the chamber. Subsequently, a frequency sweep measurement was performed near the resonant frequency to obtain the frequency response curve of the composite sensitized quartz tuning fork, and the corresponding resonant frequency f was recorded.

[0088] By calculating the change in resonant frequency f relative to the reference resonant frequency f0 under different concentration conditions, the relationship between the resonant frequency drift and the acetylene gas concentration can be obtained. The test results are as follows: Figure 3 As shown in Table 2.

[0089] 5. Relationship between resonant frequency drift and methane gas concentration: The composite sensitized quartz tuning forks prepared in the examples and comparative examples were installed in a sealed gas testing chamber, with both arms fully exposed to the gas environment to be tested. During the test, high-purity nitrogen (purity ≥99.999%) was used as the carrier gas and reference gas, and a methane standard gas mixture with a volume fraction of 1000 ppm was used as the concentration source. The methane standard gas and high-purity nitrogen were dynamically diluted using a mass flow controller to obtain methane test gases of different concentrations.

[0090] Before the test, high-purity nitrogen was continuously introduced into the test chamber to purge the system for 10 minutes to eliminate residual gas and stabilize the baseline. Then, the composite sensitized quartz tuning fork was excited by a function generator, and its reference resonant frequency f0 was measured under pure nitrogen conditions. Following this, methane mixtures with concentrations of 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, and 1000 ppm were sequentially introduced into the test chamber. At each concentration, the gas flow rate was kept stable, and the test was allowed to proceed for approximately 3 minutes to allow the gas concentration to stabilize within the chamber. Subsequently, a frequency sweep measurement was performed near the resonant frequency to obtain the frequency response curve of the composite sensitized quartz tuning fork, and the corresponding resonant frequency f was recorded.

[0091] By calculating the change in resonant frequency f relative to the reference resonant frequency f0 under different concentration conditions, the relationship between the resonant frequency drift and the methane gas concentration can be obtained. The test results are shown in Table 3.

[0092] Table 2 - Relationship between resonant frequency drift and acetylene concentration in the embodiments and comparative examples of this application using composite sensitized quartz tuning forks. Table 3 - Relationship between resonant frequency drift and methane concentration in the embodiments and comparative examples of this application using composite sensitized quartz tuning forks. Comparing the schemes of Examples 1 and 6-8 in Table 2-3, it can be seen that the coverage rate of Pd nanoclusters on the surface of the rGO substrate in Examples 1 and 6-7 is between 0.5% and 5%. Since Pd metal has a strong surface interaction ability with molecules containing unsaturated carbon-carbon bonds, when Pd nanoclusters are dispersed on the surface of the rGO substrate at this low coverage rate, the rGO sheet structure provides a stable loading substrate for Pd nanoclusters and effectively inhibits the aggregation of nanoparticles. This allows Pd nanoclusters to maintain a high degree of dispersion and effective surface area, forming a large number of spatially uniformly distributed acetylene active adsorption sites, thereby significantly improving the adsorption efficiency of acetylene molecules on the surface of the sensitization layer and ensuring that the composite sensitization layer does not have an unacceptable negative impact on the resonant frequency and quality factor of the quartz tuning fork. Under the same concentration conditions, the resonant frequency drift caused by acetylene is significantly greater than that caused by methane, indicating that the rGO-Pd composite sensitization structure has a stronger adsorption capacity for acetylene molecules containing unsaturated C≡C bonds, thus exhibiting better gas selectivity. Its resonant frequency can show a stable and monotonic drift trend with the increase of acetylene concentration.

[0093] Compared to Example 1, the Pd nanoclusters in Example 8 have a 7% coverage rate on the rGO substrate surface, which is relatively high. However, this reduces the spacing between the Pd nanoclusters on the rGO substrate surface, making it easier for some nanoclusters to come into contact with each other or even form localized sheets. This leads to decreased dispersibility and a reduced effective specific surface area, preventing a further increase in the number of active sites per unit area that can participate in gas adsorption. Simultaneously, the higher coverage of Pd nanoclusters creates a relatively dense metallic distribution on the rGO substrate surface, potentially obstructing the original porous structure and gas transport channels of the rGO sheets. This hinders the diffusion and adsorption of acetylene molecules to the active sites, thus reducing the improvement in adsorption efficiency. Therefore, when the Pd nanocluster coverage exceeds 5%, although the loading increases, the detection performance is not further improved due to the combined effects of decreased dispersibility, limited gas transport, and enhanced mass loading effect. In fact, it may even negatively impact the stable detection of acetylene gas to some extent.

[0094] By comparing the schemes of Examples 1 and 9-11 in Table 2-3, it can be seen that the mass of the composite sensitization layer in Examples 1 and 9-10 is between 0.1% and 1% of the effective mass of the quartz tuning fork, and the corresponding resonant frequency change is about 0.05% to 0.5%. This can ensure that the resonant frequency change rate is less than 1% and the quality factor decreases by no more than 20%, so that the mass loading and acoustic performance of each sensitized quartz tuning fork are kept within a controllable range. Its resonant frequency can show a stable and monotonous drift trend with the increase of acetylene concentration.

[0095] Compared to Example 1, in Example 9, the mass of the composite sensitizing layer is 0.2% of the effective mass of the quartz tuning fork. The mass loading is too small, resulting in a small additional mass of the composite sensitizing layer on the quartz tuning fork vibration system. This makes the increase in the equivalent vibration mass not obvious, the amplitude shift of the resonant frequency is small, and the sensitivity of acetylene gas detection is reduced.

[0096] Compared to Example 1, in Example 11, the mass of the composite sensitizing layer is 1.5% of the effective mass of the quartz tuning fork. This mass loading exceeds the upper limit of the preferred range of 0.1%-1%. At this point, the added mass of the composite sensitizing layer to the quartz tuning fork vibration system is significantly increased, resulting in a substantial increase in its equivalent vibrating mass and a significant shift in the resonant frequency. Simultaneously, excessive mass loading enhances the energy dissipation effect during vibration, increasing the internal damping of the quartz tuning fork and significantly reducing the quality factor. This reduces the sharpness and signal-to-noise ratio of the resonant response, hindering the accurate detection of minute frequency changes. Furthermore, an excessively thick composite sensitizing layer may introduce additional mechanical inhomogeneities and interfacial stresses during vibration, weakening the stable coupling between the rGO substrate and the quartz vibrating arm. This makes it difficult to effectively convert the mass change caused by gas adsorption into a stable resonant frequency signal, thus affecting the repeatability and long-term stability of the detection results. Therefore, when the mass fraction of the composite sensitizing layer exceeds 1%, although the mass loading increases, the overall detection performance is actually inferior to that of the examples within the preferred range due to factors such as deteriorated resonant performance and decreased signal stability.

[0097] like Figure 3 As shown, Comparative Example 3 uses a commercially available quartz tuning fork, and its resonant frequency does not show a significant drift trend with increasing acetylene concentration. Compared to Comparative Example 3, the rGO in the composite sensitization layer set in Example 1 has a two-dimensional sheet structure and a large specific surface area. Its surface contains abundant defect sites and π-conjugated electronic structures, which can provide a large number of adsorption sites for acetylene molecules. At the same time, when Pd nanoclusters are dispersed on the rGO surface with a low coverage, a large number of spatially uniform active adsorption sites can be formed. rGO provides a large-area adsorption interface and a stable mechanical coupling channel. The two form a synergistic sensitization effect, thereby significantly improving the adsorption efficiency of acetylene molecules on the surface of the sensitization layer. Under different acetylene gas concentrations, as the concentration of acetylene in the analyte increases, the adsorption of acetylene molecules on the surface of the rGO-Pd composite sensitized layer increases, which increases the equivalent vibrational mass of the composite sensitized quartz tuning fork, resulting in a measurable decrease in its resonant frequency. The resonant frequency exhibits a stable and monotonic drift trend with increasing acetylene concentration. This resonant frequency drift has a good correlation with the acetylene concentration and can be used as an effective criterion for quantitative detection of acetylene gas.

[0098] Compared to Example 1, the composite sensitized quartz tuning fork of Comparative Example 1 did not have Pd nanoclusters, but only retained the rGO substrate layer. Although rGO has a large specific surface area and a certain gas adsorption capacity, its adsorption of acetylene molecules mainly relies on physical adsorption or weak interactions. It lacks the enhanced adsorption effect of metal active sites on C≡C triple bonds, resulting in low adsorption strength and selectivity of acetylene molecules. It is difficult to form an efficient gas-sensitized layer interaction interface, which in turn results in a small resonant frequency drift and reduced detection sensitivity.

[0099] Compared to Example 1, the composite sensitized quartz tuning fork in Comparative Example 2 did not have an rGO substrate layer; instead, Pd nanoclusters were dispersed only on the vibrating arm surface. Due to the lack of a continuous rGO sheet structure as a supporting substrate, the Pd nanoclusters were prone to localized aggregation or uneven distribution on the vibrating arm surface, making it difficult to maintain a highly dispersed state and resulting in a reduction in the number of effective active sites. Simultaneously, the lack of the porous structure and gas diffusion channels provided by rGO hindered the enrichment and transport of acetylene molecules on the sensitized layer surface, thereby reducing the overall adsorption efficiency and weakening the coupling effect of gas adsorption on the quartz tuning fork vibration system.

[0100] Compared to Example 1, the hierarchical structure of the rGO substrate and Pd nanoclusters in Comparative Example 4 is reversed; the Pd nanoclusters are located near the vibrating arm surface, while rGO is located on the outer layer. This structure prevents the Pd nanoclusters from being fully exposed to the gaseous environment, as their active sites are partially covered or shielded by rGO, reducing the probability of direct contact with acetylene molecules. Simultaneously, although the outer layer of rGO has some adsorption capacity, it hinders the diffusion of gas to the inner Pd nanoclusters, thereby weakening the catalytic / adsorption effect of the Pd nanoclusters and reducing the overall sensitization efficiency. Furthermore, this structure is not conducive to forming a stable and effective mechanical coupling path, making it difficult to efficiently transfer the mass change caused by adsorption to the vibration system of the quartz tuning fork.

[0101] In summary, Comparative Examples 1, 2, and 4, due to the lack of Pd nanoclusters, the lack of an rGO substrate layer, or an unreasonable arrangement of the sensitization layer structure, respectively, could not form a composite sensitization structure with the synergistic effect of rGO and Pd nanoclusters as in Example 1. Consequently, they all exhibited poor performance in terms of gas adsorption efficiency, signal conversion capability, and detection stability. This further illustrates that the specific structural combination of the rGO substrate layer and Pd nanoclusters in this application plays an important role in achieving highly sensitive acetylene detection.

[0102] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A composite sensitized quartz tuning fork for acetylene detection, characterized in that, The device includes a quartz tuning fork and a composite sensitizing layer. The quartz tuning fork includes two parallel and spaced-apart resonant arms. The composite sensitizing layer is disposed on the opposite inner surfaces of the two resonant arms. The composite sensitizing layer includes an rGO substrate layer and a Pd nanocluster arranged sequentially along the direction away from the resonant arms.

2. The composite sensitized quartz tuning fork for acetylene detection according to claim 1, wherein, The thickness of the rGO substrate is 50-200 nm.

3. The composite sensitized quartz tuning fork for acetylene detection of claim 1, wherein, The coverage of the Pd nanoclusters on the surface of the rGO substrate is 0.5%-5%.

4. The composite sensitized quartz tuning fork for acetylene detection of claim 1, wherein, The average particle size of the Pd nanoclusters is 2-10 nm; And / or, the equivalent height of the Pd nanoclusters is 1-5 nm.

5. The composite sensitized quartz tuning fork for acetylene detection of claim 1, wherein, The composite sensitization layer accounts for 0.5%-1% of the mass of the quartz tuning fork.

6. The composite sensitized quartz tuning fork for acetylene detection of claim 1, wherein, The mass of the quartz tuning fork is 60-90 μg.

7. The composite sensitized quartz tuning fork for acetylene detection as described in claim 1, characterized in that, The quartz tuning fork is a standard 32.768 kHz commercial quartz tuning fork.

8. A method for preparing a composite sensitized quartz tuning fork for acetylene detection as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) The rGO dispersion was drop-coated onto the corresponding surface of the resonant arm and dried to form the rGO substrate layer; (2) H2PdC was dropped onto the rGO substrate. l4 The solution was mixed with an equal volume of NaBH4 solution for in-situ reduction to generate Pd nanoclusters. After rinsing and drying, a composite sensitized quartz tuning fork was obtained.

9. The method for preparing a composite sensitized quartz tuning fork for acetylene detection according to claim 8, wherein, In step (1), the concentration of rGO in the rGO dispersion is 0.1-0.5 mmol / L; And / or, in step (2), the H2PdC l4 H2PdC in solution l4 The concentration is 0.05-0.5 mmol / L; And / or, in step (2), the concentration of NaBH4 in the NaBH4 solution is 0.5-2 mmol / L.

10. An acetylene detection device, characterized by Including the composite sensitized quartz tuning fork as described in any one of claims 1-7.

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