Vanadium oxide, preparation method and application of vanadium oxide as Raman indicator for monitoring hydrogen diffusion and in hydrogen separation membrane

Abstract

The invention discloses a vanadium oxide, a preparation method and application of the vanadium oxide as a Raman indicator for monitoring hydrogen diffusion and in a hydrogen separation membrane. According to the method, vanadium oxide (VOx) prepared by adopting a chemical vapor deposition method is used as a Raman indicator, and the dynamic distribution and transmission path of hydrogen are accurately tracked through Raman spectrum change caused by interaction of the vanadium oxide (VOx) and the hydrogen. According to the invention, visualization of a transmission path of hydrogen in the separation membrane is realized through a Raman spectrum technology, and important experimental basis and design guidance are provided for development of a novel efficient gas separation membrane.

Description

Technical Field

[0001] The invention belongs to the technical field of membrane separation, and more specifically, relates to a vanadium oxide, a preparation method and an application of the vanadium oxide as a Raman indicator for monitoring hydrogen diffusion and in a hydrogen separation membrane. Background Art

[0002] In the current context of carbon neutrality, as the strategic position of hydrogen energy becomes increasingly prominent, how to efficiently separate hydrogen from industrial by-products has become a technical problem that urgently needs to be solved. Traditional separation methods, such as distillation, compression condensation or adsorption, are often accompanied by high energy consumption or require the use of specific additives, while membrane separation technology has gradually become the preferred choice due to its economy and environmental friendliness. In particular, with the development of two-dimensional material technology, materials such as MXene, layered silicate (RUB-15), and metal organic frameworks (MOFs) have provided new possibilities for the preparation of membrane materials with high separation performance.

[0003] These two-dimensional nanosheet materials can be stacked in parallel to form ultra-thin membrane structures with nanoscale channels, through which macromolecular gases can be effectively excluded, thereby achieving highly selective permeation of hydrogen. However, in practical applications, the separation efficiency of such membranes, especially selectivity and permeability, is often significantly affected by the geometry of the transmission channels in the membrane. Studies have shown that the transmission channels in the membrane that are parallel or perpendicular to the two-dimensional materials exhibit different characteristics in terms of diffusion resistance. Nevertheless, it is still unclear how these different channel orientations specifically affect the performance of selective membranes based on the above materials, and this uncertainty has exacerbated the gap between theoretical models and practical applications. Monitoring mass diffusion in separation membranes based on two-dimensional materials has always been a major challenge. At present, some attempts have used techniques such as transmission electron microscopy, super-resolution fluorescence microscopy, and scanning electrochemical microscopy to track ion diffusion paths. In contrast, tracking the diffusion process of gas molecules, especially hydrogen, is more difficult because gas molecules lack clear diffusion traces in traditional interface and surface characterization techniques. In addition, due to the non-polar nature of hydrogen molecules, their interaction with polar or charged materials is extremely limited, making their adsorption process difficult.

[0004] Therefore, there is an urgent need in the art for a method that can be effectively used to monitor the diffusion of hydrogen in hydrogen separation membranes, and a method to further understand the diffusion path of hydrogen in two-dimensional membranes, so as to accurately and objectively reveal the behavior of hydrogen through selective membranes, thereby improving the efficiency of gas separation technology and reducing R&D costs. Summary of the invention

[0005] 1. Problem to be solved

[0006] The first purpose of the present invention is to provide a vanadium oxide to solve the problem that hydrogen is difficult to monitor in the prior art. The vanadium oxide has a changed Raman spectrum when in contact with hydrogen, thereby realizing hydrogen monitoring.

[0007] Based on the first aspect of the present invention, the vanadium oxide can be used as a Raman indicator for monitoring hydrogen diffusion.

[0008] The second purpose of the present invention is to address the problem that the diffusion path of hydrogen in the existing two-dimensional material-based selective membrane is difficult to monitor. The present invention provides a hydrogen separation membrane, in which the vanadium oxide is loaded on the surface of the hydrogen separation membrane base membrane, and the vanadium oxide Raman spectrum is used to indicate whether hydrogen passes through the hydrogen separation membrane base membrane and the diffusion path.

[0009] 2. Technical solution

[0010] In the present invention, VO was first discovered x After contact with hydrogen, specific Raman peaks will change regularly. Based on this, the present invention proposes a strategy based on vanadium oxide as an indicator to detect the presence of hydrogen (H2) and its transmission path in the two-dimensional hydrogen separation membrane base membrane through confocal Raman spectroscopy. In the present invention, the Raman spectrum changes caused by the interaction between hydrogen and the indicator are used to locate the transmission trajectory of hydrogen in the membrane. This method can not only reveal the path of hydrogen through the membrane, but also evaluate the selective permeability of the membrane by analyzing the phase change of the indicator caused by hydrogen, thereby providing a new direction and technical support for the design and manufacture of efficient hydrogen separation membranes.

[0011] [Method for preparing vanadium oxide]

[0012] The first aspect of the present invention provides a method for preparing vanadium oxide, comprising the steps of using chemical vapor deposition (CVD) in a mixed atmosphere formed by argon and hydrogen, using vanadium chloride and vanadium pentoxide as raw materials, and growing them at a temperature of 500°C±10°C for 5 to 15 minutes to obtain the vanadium oxide.

[0013] In the above temperature range and mixed atmosphere, vanadium oxide (VO x ), after the vanadium oxide contacts with hydrogen, the vanadium oxide undergoes a phase change, which results in a change in the Raman peak intensity. Specifically, the vanadium oxide transforms from the M1 phase to the rutile phase at 197 cm -1 The attenuated Raman peak is displayed at the position, thus enabling hydrogen monitoring.

[0014] As a preferred embodiment of any embodiment of the first aspect of the present invention, the vanadium pentoxide contains sodium chloride, and the mass of the sodium chloride accounts for 10-20% of the total mass of the vanadium pentoxide and the sodium chloride. The presence of sodium chloride can promote the sublimation of the vanadium pentoxide, so that the vanadium pentoxide can be transferred to the gas phase during the reaction and react with the vanadium chloride to form vanadium oxide.

[0015] As a preferred embodiment of any embodiment of the first aspect of the present invention, the volume ratio of argon to hydrogen in the mixed atmosphere formed by the argon and hydrogen is (1.8-2.2): 1. Preferably, the volume ratio of argon to hydrogen in the mixed atmosphere formed by the argon and hydrogen is 2: 1. For example, a mixed gas is formed by introducing an argon flow rate of 10 sccm and a H2 flow rate of 5 sccm.

[0016] It should be noted that the volume ratio of argon to hydrogen in the mixed atmosphere formed by argon and hydrogen should be controlled within the above range to ensure that the vanadium oxide has sufficient Raman response when used.

[0017] [Vanadium Oxide]

[0018] The second aspect of the present invention provides a vanadium oxide prepared by the preparation method of the first aspect of the present invention, wherein the vanadium oxide has a wavelength of 197±1cm at an excitation wavelength of 532nm. -1 Here, the Raman peak with 197±1cm at 532nm excitation wavelength can be -1 The Raman peak is used as a sign that vanadium oxide with hydrogen response function has been prepared. When the prepared vanadium oxide meets this condition, it can be used for hydrogen monitoring.

[0019] [Raman indicators for monitoring hydrogen diffusion]

[0020] The third aspect of the present invention provides a Raman indicator for monitoring hydrogen diffusion, wherein the Raman indicator comprises the vanadium oxide according to the second aspect of the present invention, and the Raman indicator is located at 197±1cm at an excitation wavelength of 532nm after contacting with hydrogen compared to not contacting with hydrogen. -1 The Raman peak area at is reduced.

[0021] The principle is the same as that of the first aspect of the present invention. After the vanadium oxide contacts with hydrogen, the vanadium oxide transforms from the M1 phase to the rutile phase. -1 The attenuated Raman peak intensity is shown at the position, so that hydrogen can be monitored. Therefore, vanadium oxide can be used as or can be used as one of the components to constitute a Raman indicator for monitoring hydrogen diffusion.

[0022] As a preferred embodiment of any one of the third aspects of the present invention, the vanadium oxide is a two-dimensional vanadium oxide film, and the thickness of the two-dimensional vanadium oxide film is 20 to 50 nm.

[0023] It should be noted that when the vanadium oxide used as a Raman indicator is a two-dimensional film, its thickness should be within the above-mentioned appropriate range. When the thickness is too high, for example, higher than 50 nm, the vanadium oxide crystal phase structure far away from the hydrogen changes slowly, making it difficult to monitor the changes from the Raman spectrum. When the thickness is too thin, for example, lower than 20 nm, the vanadium oxide film is prone to discontinuity, affecting its film structure as an effective monitor.

[0024] Preferably, the thickness of the vanadium oxide two-dimensional film is 25-40 nm.

[0025] More preferably, the vanadium oxide two-dimensional film has a thickness of 25-35 nm. Within this thickness range, a large Raman response signal change can be ensured.

[0026] [Application of Raman indicators for monitoring hydrogen diffusion in hydrogen detection]

[0027] The fourth aspect of the present invention provides the use of the Raman indicator for monitoring hydrogen diffusion described in the third aspect of the present invention in detecting hydrogen, comprising:

[0028] Detecting the Raman spectrum of the Raman indicator that is not in contact with hydrogen at an excitation wavelength of 532 nm;

[0029] The Raman indicator is contacted with hydrogen at 150-250° C. for 1-4 hours;

[0030] Detecting the Raman spectrum of the Raman indicator after contacting with hydrogen at an excitation wavelength of 532 nm;

[0031] Compared with the case without contact with hydrogen, the Raman indicator is located at 197±1cm after contact with hydrogen. -1 The Raman peak area at is reduced.

[0032] The Raman peak areas and their ratios were determined by the following method:

[0033] The Raman indicator that was not exposed to hydrogen was used as a reference, and its wavelength was 197 cm at an excitation wavelength of 532 nm. -1 The Raman peak area is A0; the Raman indicator after contact with hydrogen is used as the sample to be tested. The sample to be tested has an excitation wavelength of 532nm at 197cm -1 The Raman peak area is A; the fitting 197cm -1The vibration at corresponds to the Raman peak area of ​​the lattice motion of VV, and the peak area ratio is calculated: A / A0, where A and A0 represent the Raman peak area after the Raman indicator is exposed to hydrogen and the Raman peak area without contacting hydrogen, respectively.

[0034] When the area ratio (A / A0) is lower than 1, it means that hydrogen is in contact with the Raman indicator. The lower the area ratio, the closer it is to the Raman indicator VO. x The more hydrogen.

[0035] When the area ratio (A / A0) is higher than 1, it means that the Raman indicator is not in contact with hydrogen.

[0036] As a preference of any embodiment of the fourth aspect of the present invention, the contact temperature is 150-250°C, most preferably 200°C.

[0037] As a preference of any embodiment of the fourth aspect of the present invention, the contact time is preferably 2 to 4 hours, most preferably 3 hours.

[0038] [Hydrogen separation membrane]

[0039] A fifth aspect of the present invention provides a hydrogen separation membrane, comprising:

[0040] Hydrogen separation membrane base membrane; and

[0041] The Raman indicator according to any embodiment of the third aspect of the present invention;

[0042] The Raman indicator is loaded on one side of the hydrogen separation membrane base film. In particular, it is located on the outside of the hydrogen separation membrane base film so as to detect whether hydrogen passes through the hydrogen separation membrane base film.

[0043] The transmission paths of hydrogen in the hydrogen separation membrane base film include vertical transmission channels and planar transmission channels; wherein the vertical transmission channel refers to the vertical diffusion of hydrogen through the two-dimensional material membrane (vertical diffusion). Generally, when there are vertical holes in the hydrogen separation membrane base film, the way hydrogen passes through the hydrogen separation membrane base film is vertical diffusion; wherein the planar transmission channel refers to the tiny gaps or dislocations between layers that can form microchannels, allowing hydrogen to pass through. Generally, in a non-porous membrane, there is planar diffusion through the planar transmission channel. When the above-mentioned hydrogen separation membrane is applied to hydrogen separation, after hydrogen passes through the hydrogen separation membrane base film by vertical diffusion or planar diffusion, the hydrogen contacts the Raman indicator. The Raman indicator at the position of contacting hydrogen is located at 197±1cm at an excitation wavelength of 532nm. -1 The Raman peak area at the position not in contact with hydrogen is reduced, while the Raman peak area at the position not in contact with hydrogen is located at 197±1cm at an excitation wavelength of 532nm. -1The Raman peak area at will not show a smaller change. Therefore, the above changes can be used to determine whether hydrogen has passed through the hydrogen separation membrane base film, and further determine the area on the hydrogen separation membrane base film where hydrogen has passed through.

[0044] As a preferred embodiment of any one of the fifth aspects of the present invention, the Raman indicator is a two-dimensional film of vanadium oxide, and the thickness of the two-dimensional film of vanadium oxide is preferably 20 to 50 nm.

[0045] Preferably, the thickness of the vanadium oxide two-dimensional film is 25-40 nm.

[0046] More preferably, the vanadium oxide two-dimensional film has a thickness of 25-35 nm. Within this thickness range, a large Raman response signal change can be ensured.

[0047] In this case, the Raman indicator can be located at 197 ± 1 cm at an excitation wavelength of 532 nm. -1 The diffusion mode of hydrogen in the hydrogen separation membrane base membrane is judged by the region where the Raman peak area decreases.

[0048] For example, in a typical vertical diffusion situation, hydrogen vertically permeates the hydrogen separation membrane base film, and thus is located at 197±1cm at an excitation wavelength of 532nm. -1 The area where the Raman peak area decreases is distributed on the surface of the vanadium oxide two-dimensional film.

[0049] For example, in a typical planar diffusion situation, hydrogen permeates through the edge of the hydrogen separation membrane base film, so at an excitation wavelength of 532 nm, the hydrogen permeates at 197 ± 1 cm -1 The region where the Raman peak area decreases is distributed at the edge of the vanadium oxide two-dimensional film.

[0050] For example, when the hydrogen separation membrane base film does not allow hydrogen to pass through, there is no ion at 197±1cm at the 532nm excitation wavelength on the surface and edge of the vanadium oxide two-dimensional membrane. -1 The area of ​​the Raman peak at the point where the peak decreases.

[0051] As a preferred embodiment of any embodiment of the fifth aspect of the present invention, the thickness of the hydrogen separation membrane base film is 20 to 100 nm. When the thickness of the hydrogen separation membrane base film is too thick, it will affect the measurement of Raman spectrum, resulting in the inability to accurately determine the Raman spectrum at 197 ± 1 cm at an excitation wavelength of 532 nm. -1 The Raman peak at 240 nm is eliminated, which makes it impossible for vanadium oxide to function as a Raman indicator.

[0052] Preferably, the thickness of the hydrogen separation membrane base film is 20 to 50 nm.

[0053] As a preferred embodiment of any one of the fifth aspects of the present invention, the hydrogen separation membrane base membrane is selected from one of Mxene and zeolite RUB-15 having pores with a diameter of 10 to 20 nm.

[0054] The vanadium oxide two-dimensional film of the present invention is loaded on one of the above hydrogen separation membrane base films as a Raman indicator. After hydrogen passes through the above hydrogen separation membrane base film, the Raman indicator shows a Raman indicator at 197±1cm at an excitation wavelength of 532nm. -1 The Raman peak area at the position decreases, so it can be judged that Mxene and zeolite RUB-15 with pores with diameters of 10 to 20 nm are both typical vertical diffusion hydrogen separation membrane base membranes.

[0055] As a preferred embodiment of any one of the fifth aspects of the present invention, the hydrogen separation membrane base membrane is non-porous Mxene, and the surface roughness of the non-porous Mxene is greater than or equal to 16 nm.

[0056] The vanadium oxide two-dimensional film of the present invention is loaded on the basis of a non-porous Mxene film with a surface roughness greater than or equal to 16 nm as a Raman indicator, and the surface of the Raman indicator is located at 197±1 cm at an excitation wavelength of 532 nm. -1 The region where the Raman peak area decreases is at the edge of the vanadium oxide two-dimensional film. Therefore, it can be judged that hydrogen mainly diffuses horizontally in the non-porous Mxene film with a surface roughness greater than or equal to 16 nm.

[0057] As any embodiment of the fifth aspect of the present invention, the hydrogen separation membrane base membrane is a BN membrane.

[0058] The vanadium oxide two-dimensional film of the present invention is loaded on the BN film as a Raman indicator, and the Raman indicator shows that there is almost no localization at 197±1cm at an excitation wavelength of 532nm. -1 The Raman peak area at the position decreases, so it can be judged that the hydrogen diffusion in the BN film is extremely small.

[0059] 3. Beneficial effects

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] (1) In the present invention, vanadium oxide VO is prepared by controlling the temperature range and mixed atmosphere of the chemical vapor deposition method. x After the vanadium oxide comes into contact with hydrogen, the vanadium oxide undergoes a phase change, which causes a change in the Raman peak intensity. The vanadium oxide obtained by this preparation method can realize hydrogen monitoring.

[0062] (2) The Raman indicator for monitoring hydrogen diffusion of the present invention comprises or is the aforementioned vanadium oxide. Compared with the case where the Raman indicator is not in contact with hydrogen, the Raman indicator is located at 197±1cm at an excitation wavelength of 532nm after contact with hydrogen. -1 The Raman peak area at the position is reduced, and thus it can be used to detect hydrogen diffusion.

[0063] (3) The hydrogen separation membrane of the present invention has the Raman indicator loaded on one side of the hydrogen separation membrane base membrane. When the hydrogen separation membrane is used for hydrogen separation, after hydrogen passes through the hydrogen separation membrane base membrane by vertical diffusion or planar diffusion, the hydrogen contacts the Raman indicator. The Raman indicator at the position contacting the hydrogen is located at 197±1cm at an excitation wavelength of 532nm. -1 The Raman peak area at the position not in contact with hydrogen is reduced, while the Raman peak area at the position not in contact with hydrogen is located at 197±1cm at an excitation wavelength of 532nm. -1 The Raman peak area at will not show a smaller change, therefore, it can be judged whether hydrogen has passed through the hydrogen separation membrane base membrane by the above changes;

[0064] In addition, the present invention can also use a Raman indicator at 197±1cm at an excitation wavelength of 532nm. -1 The diffusion mode of hydrogen in the hydrogen separation membrane base membrane (vertical diffusion, planar diffusion or non-diffusion) is determined by the area where the Raman peak area decreases. x Indicators are used to monitor the transport path of hydrogen in the separation membrane based on two-dimensional materials in real time; x The Raman spectral changes caused by the interaction of the indicators successfully tracked the dynamic distribution of hydrogen in real time and non-destructively; this innovative method not only improved the accuracy of monitoring, but also provided a new perspective for the in-depth understanding of the hydrogen transport mechanism and the design and optimization of selective membranes.

[0065] (4) The present invention uses Raman spectroscopy to visualize the transmission path of hydrogen in the separation membrane, which is a major innovation in gas separation technology. Experimental results show that by optimizing the assembly structure of the two-dimensional material membrane (such as adjusting the roughness of the MXene membrane) and introducing artificial or inherent pores, the transmission efficiency and selectivity of hydrogen are significantly enhanced; these findings provide important experimental basis and design guidance for the development of new and efficient gas separation membranes. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 :

[0067] (a) Schematic diagram of observing hydrogen passing through a hydrogen separation membrane using Raman spectroscopy;

[0068] (b) CVD-grown vanadium oxide (VO x ) Optical microscope image of the nanosheet at 100 times magnification;

[0069] (c) CVD-grown vanadium oxide (VO x ) Typical atomic force microscopy (AFM) images of nanosheets;

[0070] (d) CVD-grown vanadium oxide (VO x ) transmission electron microscopy (TEM) image of nanosheets; the left inset is VO x High-resolution transmission electron microscopy (HRTEM) image of the M1 phase VO x In the zone axis [1-2 2] M1 Selected area electron diffraction (SAED) experimental pattern at;

[0071] (e) VO before and after exposure to hydrogen x Electron Energy Loss Spectrum (EELS) in the relevant energy range (including vanadium L-edge and oxygen K-edge). The dark blue line below represents the original VO x The upper red line represents VO after exposure to hydrogen x .

[0072] Figure 2 :

[0073] (a) VO x VO before and after exposure to hydrogen at different temperatures x Normalized intensity of Raman spectra (50-250℃, exposure time 3h);

[0074] (b) VO x The peak at 197 cm-1 after (A) and before (A0) exposure to hydrogen at different temperatures (50-250 °C) -1 The Raman peak area ratio at

[0075] (c)VO x VO before and after exposure to hydrogen for different time periods x Normalized intensity of Raman spectra (exposure time 1-4h, 200℃);

[0076] (d) Hydrogen exposure time and VO x 197cm -1 and 229cm -1 The relationship between the Raman peak area.

[0077] Figure 3 :

[0078] (a) 20nm-MXene / VO x Schematic diagram of the heterostructure;

[0079] (b) TEM image of 20 nm-MXene nanosheets; white arrows indicate the pores in the nanosheets, and the scale bar is 50 μm;

[0080] (c) 20nm-MXene / VO x Normalized intensity of Raman spectra before and after exposure to hydrogen at different temperatures (50-250°C, exposure time 3h);

[0081] (d) 20nm-MXene / VO x After exposure to hydrogen at different temperatures (50-250°C) (A) and before exposure (A0) at 197 cm -1 The Raman peak area ratio at

[0082] (e) 20nm-MXene / VO x Normalized intensity of Raman spectra before and after exposure to hydrogen for different times (exposure time was 1-4h, 200℃);

[0083] (f) Hydrogen contact time and 20nm-MXene / VO x 197cm -1 and 229cm -1 The relationship between the Raman peak area.

[0084] Figure 4 :

[0085] (a) TEM image of a nonporous MXene nanosheet. The upper left corner shows a schematic diagram of the MXene crystal structure along the c-axis.

[0086] (b) Nonporous MXene / VO x 100x magnified optical microscope image of the heterostructure (above), the Raman mapping test area is outlined in the white box, the scale bar is 5μm; 197cm -1 The Raman peak area plots at show the situation before (lower left) and after (lower right) hydrogen exposure;

[0087] (c) Nonporous MXene / VO x Atomic force microscopy image of the heterostructure, with the pink area representing non-porous MXene and the green area representing VO x , scale bar is 2 nm;

[0088] (d) Nonporous MXene / VO x Surface roughness of heterostructure membrane (nm) before and after contact with hydrogen 197cm -1 The relationship between the Raman peak area ratios at

[0089] Figure 5 :

[0090] (a)BN / VO x Atomic force microscopy image of the heterostructure. The pink area represents non-porous BN and the blue area represents VO x Substrate; scale bar is 2nm. Below is a schematic diagram of the structure of BN crystal along the c-axis;

[0091] (b)BN / VO x 100x magnified optical microscope image of the heterostructure (above), the Raman mapping test area is outlined in the white box, the scale bar is 5μm; 197cm -1 The Raman peak area plot at shows the situation before (lower left) and after (lower right) hydrogen exposure;

[0092] (c)RUB-15 / VO x Atomic force microscopy image of the heterostructure; pink areas represent zeolite and blue areas represent VO x ; The scale bar is 2 nm; the lower left corner is a schematic diagram of the structure of the RUB-15 crystal along the c-axis;

[0093] (d) RUB-15 / VO x 100x magnified optical microscope image of the heterostructure (above), the white frame is the Raman mapping test area; the scale bar is 5μm; the image shows the 197cm -1 Raman peak area diagram at (lower left) and after contact with hydrogen (lower right);

[0094] Figure 6 :

[0095] (a) VO x Nanosheets (VO x Raman spectrum intensity of 2D film before and after exposure to nitrogen at different temperatures (exposure time is 3h);

[0096] (b) VO at different temperatures x Nanosheets (VO x The 2D membrane was located at 197 cm after (A) and before (A0) contact with nitrogen. -1 The Raman peak area ratio at . DETAILED DESCRIPTION

[0097] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs; the term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0098] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased from the market.

[0099] As used herein, the term "about" is used to provide flexibility and imprecision associated with a given term, measurement or value. The degree of flexibility for a particular variable can be easily determined by one skilled in the art.

[0100] Concentration, amount and other numerical data can be presented in range format herein.It should be understood that such range format is only used for convenience and simplicity, and should be flexibly interpreted as not only including the numerical value clearly described as range limit, but also including all single numerical values ​​or sub-ranges contained in the range, just as each numerical value and sub-range are clearly described.For example, the numerical range of about 1 to about 4.5 should be interpreted as not only including the limit value of 1 to about 4.5 clearly described, but also including single numerals (such as 2,3,4) and sub-ranges (such as 1 to 3,2 to 4, etc.).The same principle is applicable to the scope of only narrating a numerical value, such as "less than about 4.5", which should be interpreted as including all the above-mentioned values ​​and ranges.In addition, no matter how the breadth of the described range or feature is, this explanation should be applicable.

[0101] Preparation Example 1

[0102] 1. Preparation of Materials

[0103] High-purity vanadium (III) chloride powder (purity 99%) and vanadium pentoxide (V2O5) powder (purity 99%) were purchased from Anage. Sodium chloride (NaCl) powder (purity 99%) was purchased from Heowns. Nonporous MXene, 20nm-MXene (MXene with pore size 20nm) and RUB-15 nanosheet dispersion were purchased from Zhuhai Enwang Nanomaterial Technology Co., Ltd. Mica flakes (KMg3AlSi3O 10 F2) was purchased from Jilin Taizhi Technology Co., Ltd. Boron nitride (BN) was purchased from Tianjin Xiensiopude Technology Co., Ltd. Polymethyl methacrylate (PMMA, 0.7 nm) was purchased from Suzhou Boyan Micronano Technology Co., Ltd. Polydimethylsiloxane (PDMS) was purchased from Zhongke Materials.

[0104] All chemicals were used directly without further purification.

[0105] 2. Preparation Steps

[0106] The Raman indicator used to monitor hydrogen diffusion is VO x , the preparation steps are as follows:

[0107] 2.1VO xSynthesis of nanosheets

[0108] High-quality VO was grown using ambient pressure CVD technology in a single-zone quartz tube furnace. x Nanosheets. In a typical synthesis process, high-purity vanadium (III) chloride powder (9 mg, Anergy, 99%) was used as a precursor and placed in the upstream area of ​​the furnace, and a mixture of vanadium pentoxide (V2O5) powder (14 mg, Anergy, 99%) and a small amount of sodium chloride (NaCl) powder (2.5 mg, Heowns, 99%) was placed in the middle area of ​​the furnace. Mica flakes (KMg3AlSi3O 10 F2) was used as the substrate and placed in the center of the furnace above the mixture of vanadium pentoxide and sodium chloride. Prior to growth, the tube was evacuated and purged with argon (300 sccm) for 10 min. Then, the temperature was set at 30 °C min -1 The middle of the furnace was uniformly heated to 500°C at a speed of 10 sccm. During the growth process, a mixed gas with an argon flow rate of 10 sccm and a H2 flow rate of 5 sccm was introduced for VO x The growth was maintained at 500°C and ambient pressure for 10 minutes. After the growth was completed, the furnace was naturally cooled to room temperature, and VO was obtained on the mica substrate. x Nanosheets.

[0109] 2.2VO x Transfer of nanosheets

[0110] First, in the case of VO x Nanosheets are spin-coated with polymethyl methacrylate (PMMA) on a mica substrate. PMMA / VO x The PMMA / VO composite was baked at 130 °C for 10 min and then soaked in deionized water for 6 h. After soaking, the PMMA / VO composite was carefully placed in water with tweezers. x The nanosheets were peeled off from the mica substrate and then transferred to the target substrate (silicon dioxide / silicon).

[0111] Will be loaded with PMMA / VO x The target substrate of the nanosheets was heated at 100 °C for 1 h to evaporate the residual moisture and enhance the PMMA / VO x The adhesion between the nanosheets and the substrate. x The target substrate of the nanosheet was immersed in acetone for 10 min to dissolve the PMMA and make the VO x The nanosheets remain on the target substrate. Finally, the VO x Nanosheets are successfully transferred to the target substrate, that is, VO loaded on a silicon dioxide / silicon substrate is obtained. x Nanosheets (VO x / SiO2 / Si).

[0112] 2.3 Hydrogen separation membrane base membrane / VO x Preparation of heterostructures

[0113] As VO x One of the applications of nanosheets is to convert VO x Nanosheets loaded on various hydrogen separation membrane base membranes to form hydrogen separation membrane base membrane / VO x Heterostructure, making VO x The nanosheets serve as an indicator of hydrogen after passing through the hydrogen separation membrane. When hydrogen passes through the hydrogen separation membrane, it reacts with the VO2O3 loaded on the other side of the hydrogen separation membrane. x Nanosheets contact, making VO x VO in nanosheets x A change in the Raman peak occurs, thereby indicating the presence of hydrogen.

[0114] Hydrogen separation membrane base membrane / VO x Preparation of heterogeneous structures: Nonporous MXene, 20nm-MXene (MXene with pore size of 20nm) and RUB-15 nanosheet dispersions were diluted to 1 mg / ml. 1 mg / ml of the above nanosheet dispersions were dropped onto the VO2 / silicon substrate prepared in step 2.2. x VO on nanosheets x On one side of the nanosheet, spin coating was performed at 3000 rpm for 15 seconds to obtain the following on the silicon dioxide / silicon substrate:

[0115] 20nm-MXene / VO x Heterostructure (20nm-MXene layer thickness is about 40nm, VO x The layer thickness is about 30nm);

[0116] Non-porous MXene / VO x Heterostructure (non-porous MXene layer thickness is about 50nm, VO x The layer thickness is about 30nm);

[0117] RUB-15 / VO x Heterostructure (the thickness of RUB-15 layer is about 80-100nm, VO x The layer thickness is about 30 nm).

[0118] BN / VO x Fabrication of heterostructures: Defect-free boron nitride nanosheets with a thickness of 15.4 nm were obtained by mechanical exfoliation, and then the BN nanosheets were transferred to VO via PDMS using a dry transfer method. x On the substrate, BN / VO is obtainedx Heterostructure (BN layer thickness is about 15.4nm, VO x The layer thickness is about 30 nm).

[0119] 3. Indicator VO x Characterization

[0120] 3.1VO x Optical microscope image of nanosheets

[0121] like Figure 1 (b) shows VO synthesized in step 2.1 of Preparation Example 1 x Optical microscope image of the nanosheet at 100x magnification.

[0122] 3.2VO x AFM image of nanosheets:

[0123] like Figure 1 (c) shows the VO after transfer in step 2.2 of preparation example 1. x AFM image of nanosheets, VO x The thickness of the nanosheet is about 30 nm.

[0124] 3.3VO x TEM image of nanosheets:

[0125] like Figure 1 (d) shows the VO after transfer in step 2.2 of preparation example 1. x TEM image of nanosheets.

[0126] 3.4 20nm-MXene / VO x Characterization of heterostructures:

[0127] like Figure 3 (a) shows the 20nm-MXene / VO obtained in step 2.3 of Preparation Example 1 x Schematic diagram of the heterostructure. Figure 3 (b) is the TEM image of the 20 nm-MXene nanosheet used in step 2.3 of Preparation Example 1. The white arrows indicate the pores in the nanosheet.

[0128] 3.5 TEM image of nonporous MXene nanosheets:

[0129] like Figure 4 (a) shows a TEM image of the non-porous MXene nanosheet used in step 2.3 of Preparation Example 1. The upper left corner shows a schematic diagram of the MXene crystal structure along the c-axis.

[0130] 3.6 Nonporous MXene / VO x Heterogeneous structures:

[0131] like Figure 4 (b) shows non-porous MXene / VO x Optical microscope image of the heterostructure at 100x magnification (above), with the Raman spectroscopy test area outlined in the white box.

[0132] 3.7BN / VO x Heterogeneous structures:

[0133] like Figure 5 (a) shows BN / VO x Atomic force microscopy image of the heterostructure. The pink area represents non-porous BN and the blue area represents VO x The base is shown below, and the schematic diagram of the structure of the BN crystal along the c-axis is shown below. Figure 5 (b) shows BN / VO x Optical microscope image of the heterostructure at 100x magnification (top).

[0134] 3.8RUB-15 zeolite / VO x Heterogeneous structures:

[0135] like Figure 5 (c) shows RUB-15 / VO x Atomic force microscopy image of the heterostructure. The pink area represents zeolite and the blue area represents VO x substrate; the lower right corner is a schematic diagram of the structure of the RUB-15 crystal along the c-axis; Figure 5 (d) shows RUB-15 / VO x Optical microscope image of the heterostructure at 100x magnification (top).

[0136] Test Case

[0137] Principle of Raman spectroscopy

[0138] Raman spectroscopy is a spectroscopy technique based on inelastic scattering, in which the incident light interacts with the sample molecules to produce energy transfer, resulting in a change in the frequency of the scattered light. This change reflects specific information about the vibration mode within the molecule, which can be used to identify and analyze the chemical structure and molecular composition of the material.

[0139] When a laser source is irradiated onto a sample, most of the light is elastically scattered at the same frequency (Rayleigh scattering). However, a small portion of the light interacts with the vibrational energy levels of the sample molecules, resulting in scattered light with a frequency different from the incident light frequency. This portion of light is called Raman scattered light. The frequency change (Raman shift) of the scattered light is determined by the vibrational mode of the molecule, and each chemical bond and molecular structure has its own specific Raman fingerprint.

[0140] In the technical solution of the present invention, VO was first discovered xAfter contact with hydrogen, a regular change of specific Raman peaks occurs, so VO x As an indicator, the Raman peaks corresponding to the phase change behavior under different hydrogen contact time are used as the key indicators for monitoring. x When in contact or through a two-dimensional hydrogen separation base film with VO x When in contact, VO x The structural and chemical states of the -1 The Raman peak intensity (area) at the two-dimensional membrane decreases, so the transmission of hydrogen can be monitored by Raman spectroscopy. Furthermore, the changes in these Raman peaks can accurately show the transmission path and interaction of hydrogen in the two-dimensional membrane, thus providing an experimental basis for efficient hydrogen separation.

[0141] In the measurement process of the embodiment of the present invention, all Raman spectrum measurement results are obtained using a confocal Raman spectrometer equipped with a 532 nm laser source, controlled by WiRE 5.5 software.

[0142] For testing at room temperature, environmental conditions (such as temperature and relative humidity) are controlled by the laboratory environment to ensure stability during testing. The temperature (T) is usually maintained at about 298K (25°C) and the relative humidity (RH) is controlled at about 50%.

[0143] Test Example 1

[0144] VO at different reaction temperatures x Raman spectrum changes of nanosheets in hydrogen

[0145] First, the VO prepared in step 2.2 of Preparation Example 1 was measured by Raman spectrometer. x Raman spectra of nanosheets. Before each measurement, ensure that the sample is placed stably on the sample stage of the Raman spectrometer and align the laser beam accurately to focus on the target area. The frequency range for measurement is set within the Raman active region (100 cm -1 -3000cm -1 ) to ensure that all key Raman active peaks are captured.

[0146] In this test case, control VO x The nanosheets were exposed to hydrogen for 3 hours and the hydrogen concentrations at 197 and 229 cm-1 were measured at ambient temperatures of 50, 100, 150, 200, and 250 °C. -1 The Raman peak intensity at 197 cm at an excitation wavelength of 532 nm was taken as a reference. -1 The Raman peak area is A0;

[0147] like Figure 2As shown in (a), after exposure to a 5sccm hydrogen environment for 3 hours, as the ambient temperature rises from 50°C to 250°C, the 197cm -1 and 229cm -1 The intensity of the Raman peak at is significantly reduced.

[0148] In order to further explore the relationship between Raman signals and contact temperature in hydrogen environment, Figure 2 As shown in (b), VO at different temperatures is calculated. x Nanosheets before and after contact with hydrogen 197cm -1 The attenuation ratio of the Raman peak area at . An area ratio (A / A0) below 1 indicates hydrogen diffusion. The lower the area ratio, the more hydrogen reaches the indicator. Figure 2 The results in (b) show that at 200°C, 197 cm -1 The Raman peak area of ​​VO decreased most significantly, with a ratio of 0.57 to the original peak area. x The change is because hydrogen reduces the oxidation state of vanadium, reduces oxygen vacancies, and moves the lattice structure toward rutile VO2, resulting in the attenuation of the Raman peak.

[0149] Test Example 2

[0150] VO at different reaction times x Raman spectrum changes of nanosheets in hydrogen

[0151] First, the VO prepared in step 2.2 of Preparation Example 1 was measured by Raman spectrometer. x Raman spectra of nanosheets. Before each measurement, ensure that the sample is placed stably on the sample stage of the Raman spectrometer and align the laser beam accurately to focus on the target area. The frequency range for measurement is set within the Raman active region (100 cm -1 -3000cm -1 ) to ensure that all key Raman active peaks are captured.

[0152] In this test case, control VO x The nanosheets were exposed to hydrogen for different times, and hydrogen was introduced from a high-purity gas cylinder through a precise flow controller to ensure a constant flow rate and pressure of hydrogen.

[0153] The ambient temperature was controlled at 200°C and the 197 cm-1 hydrogen contact time was measured from 1 to 4 hours. -1 and 229cm -1 The Raman peak intensity at 1000 nm was used to study the effect of hydrogen contact time on VO x The influence of phase transition behavior.

[0154] from Figure 2 It can be seen from (c) and 2(d) that 229cm -1The Raman peak at 197cm -1 The Raman peak area at α decreased sharply in the first hour and then stabilized after 2 hours.

[0155] Test Example 3

[0156] VO x EELS of nanosheets in hydrogen

[0157] The ambient temperature was controlled at 200°C, and the VO was measured under the conditions of no contact with hydrogen and a hydrogen contact time of 3 hours. x Energy loss of electrons in the relevant energy range of the nanosheet, including the vanadium L-edge and oxygen K-edge.

[0158] VO x EELS of nanosheets: Figure 1 (e) shows VO prepared in step 2.2 of Preparation Example 1. x The electron energy loss spectrum in the relevant energy range of the nanosheet (including vanadium L-edge and oxygen K-edge) is due to VO x There are two valence states of vanadium in the nanosheets. When hydrogen is present, the oxidation state of vanadium decreases, realizing the conversion of valence state. Such valence state conversion is reflected in the change of Raman spectral peaks, thus realizing VO x Nanosheets indicate H2.

[0159] Test Example 4

[0160] VO at different temperatures x Raman spectra of nanosheets in nitrogen First, the VO prepared in step 2.2 of Preparation Example 1 was measured using a Raman spectrometer. x Raman spectra of nanosheets. Before each measurement, ensure that the sample is placed stably on the sample stage of the Raman spectrometer and align the laser beam accurately to focus on the target area. The frequency range for measurement is set within the Raman active region (100 cm -1 -3000cm -1 ) to ensure that all key Raman active peaks are captured.

[0161] The VO was tested before and after exposure to nitrogen (3h). x The Raman peak intensity and peak area of ​​the nanosheets at 50℃, 100℃, 150℃, 200℃, and 250℃. The Raman indicator that was not in contact with hydrogen was used as a reference. The peak intensity of the nanosheets at 197cm -1 The Raman peak area is A0;

[0162] Tests found that Figure 6 As shown in (a) and (b), under nitrogen environment, VO x The nanosheets have a 197 cm -1The peak area of ​​the Raman spectrum of the nanosheets increases compared to the original peak area. This is because the oxidation state of vanadium remains essentially unchanged under nitrogen exposure, thereby maintaining the crystallinity of the nanosheets and enhancing the Raman signal from the higher-order structure.

[0163] In addition, we also found that the above-mentioned VO induced by hydrogen or nitrogen x The lattice change is irreversible in air. Therefore, VO x Nanosheets at 197 cm -1 The Raman fingerprint at can be used to show the diffusion of hydrogen.

[0164] Test Example 5

[0165] 20nm-MXene / VO x Raman Detection of Heterostructures in Hydrogen

[0166] First, the 20nm-MXene / VO prepared in step 2.3 of Preparation Example 1 was measured by Raman spectrometer. x Raman spectra of heterostructures. Before each measurement, ensure that the sample is placed stably on the sample stage of the Raman spectrometer and align the laser beam accurately to focus on the target area. The frequency range for measurement is set within the Raman active region (100cm -1 -3000cm -1 ) to ensure that all key Raman active peaks are captured.

[0167] The hydrogen contact time was controlled to be 3 hours, and the Raman peak intensity was tested at ambient temperatures of 50°C, 100°C, 150°C, 200°C, and 250°C. The Raman indicator that was not in contact with hydrogen was used as a reference, and its peak intensity at 197cm -1 The Raman peak area is A0; Figure 3 (c) shows that compared with bare VO x The Raman fingerprint of the H2 reaction in the indicator is similar, 197 cm -1 and 229cm -1 The peak intensity at decays with increasing temperature (50℃ to 250℃). Figure 3 As shown in (d), statistical analysis shows that 197cm -1 The ratio of the Raman peak areas reaches a minimum of 0.33 at 200°C.

[0168] As for the relationship between contact time and Raman peak intensity, the ambient temperature was controlled at 200 °C and the 197 cm-1 peak intensity was measured when the hydrogen contact time was from 1 hour to 4 hours. -1 and 229cm -1 The Raman peak intensity at .

[0169] like Figure 3 (e) and Figure 3 (f) shows 20nm-MXene / VO x The optimal contact time for the heterostructure is 1 hour, which is comparable to that of bare VO x The above results show that hydrogen can activate VO by penetrating the 20nm-MXene membrane with a pore size of 20nm. x Indicator, namely VO x The indicator can be applied to the surface of 20nm-MXene film through VO x The changes in the Raman spectrum detect the diffusion of hydrogen.

[0170] That is, in this test case, through VO x The Raman spectrum changes of the nanosheets indicate the presence of hydrogen that permeates the 20nm-MXene film, that is, the 20nm-MXene film can be used as a hydrogen permeation membrane; it also shows that VO x Nanosheets can be loaded on the surface of hydrogen separation membrane substrate as Raman indicators for monitoring hydrogen diffusion.

[0171] Test Example 6

[0172] Non-porous MXene / VO x Raman Detection of Heterostructures in Hydrogen

[0173] First, the non-porous MXene / VO prepared in step 2.3 of Preparation Example 1 was measured by Raman spectrometer. x Raman spectra of heterostructures. Before each measurement, ensure that the sample is placed stably on the sample stage of the Raman spectrometer and align the laser beam accurately to focus on the target area. The frequency range for measurement is set within the Raman active region (100cm -1 -3000cm -1 ) to ensure that all key Raman active peaks are captured.

[0174] After contact with the 20nm-MXene under the same conditions (200℃ for 3 hours), Raman spectra were collected and the spatial distribution of the Raman signal was obtained by mapping measurements. The Raman indicator that was not exposed to hydrogen was used as a reference, with a wavelength of 197cm at an excitation wavelength of 532nm. -1 The Raman peak area is A0;

[0175] like Figure 4 As shown in (b), the white box is the Raman mapping test area. Before exposure to H2 ( Figure 4 (b) lower left), 197cm -1 The Raman peak area integral diagram at MXene / VO x (roughness 14nm) area has a dark blue area, however, after exposure to hydrogen ( Figure 4(b) Lower right), Raman mapping shows that only part of the dark blue area becomes brighter, indicating that hydrogen penetrates in a planar diffusion manner and most of the H2 fails to penetrate.

[0176] The roughness of the corresponding areas was evaluated by atomic force microscopy, e.g. Figure 4 As shown in (d), when the roughness of the nonporous MXene 2D film is higher than 16 nm, the 197 cm -1 The peak area ratio at the bottom of the 20 nm peak is lower than 1, indicating that hydrogen has penetrated (planar diffusion). In contrast, the smooth area with a roughness of less than 14 nm does not have the 197 cm peak of contact H2 in the present invention. -1 The Raman fingerprint response at 100 nm indicates that the gas diffusion is low in the well-assembled nonporous MXene 2D film. The roughness-dependent H2 diffusion can be attributed to the narrower interlayer space between the nonporous MXene nanosheets in the well-assembled 2D film. In addition, the ripples and bubbles in the nonporous MXene 2D film indicate that the higher the roughness, the greater the gas diffusion.

[0177] That is, in this test case, through VO x The Raman spectrum changes of the nanosheets indicate that there is almost no hydrogen permeating through the non-porous MXene membrane, that is, the non-porous MXene membrane cannot be used as a hydrogen permeation membrane. At the same time, experimental verification also further shows that the diffusion of hydrogen in the non-porous MXene is extremely small, which is similar to VO x The Raman spectrum changes of the nanosheets indicate that the results are consistent.

[0178] However, when the roughness of the nonporous MXene 2D membrane is higher than 16 nm, the 197 cm -1 The peak area ratio at 0.0400 nm is lower than 1, which indicates that hydrogen permeates through the rough nonporous MXene in a planar diffusion manner.

[0179] Test Example 7

[0180] BN / VO x Raman Detection of Heterostructures in Hydrogen

[0181] First, the BN / VO prepared in step 2.3 of Preparation Example 1 was measured by Raman spectrometer. x Raman spectra of heterostructures. Before each measurement, ensure that the sample is placed stably on the sample stage of the Raman spectrometer and align the laser beam accurately to focus on the target area. The frequency range for measurement is set within the Raman active region (100cm -1 -3000cm -1 ) to ensure that all key Raman active peaks are captured.

[0182] Since the BN layer can be viewed as an ordered assembly of defect-free nanosheets, there is no xThe interlayer transport of layer diffusion is limited, so the possible hydrogen diffusion can only be used in the vertical direction, through the layer hexagonal pores.

[0183] Compared with 20nm-MXene / VO x In a similar hydrogen environment to the heterostructure test (200°C for 3 hours), the boron nitride nanosheet encapsulation area was 197 cm -1 VO x The Raman peak intensity increases significantly, such as Figure 5 (b) The lower left and right images show that this is consistent with the exposure behavior of the indicator in a nitrogen environment. According to the above results, the diffusion of hydrogen in boron nitride is extremely small compared to the layered structure of chemically exfoliated 20nm-MXene.

[0184] That is, in this test case, through VO x The Raman spectrum changes of the nanosheets indicate that there is almost no hydrogen permeating through the BN film, that is, the BN film cannot be used as a hydrogen permeation membrane. At the same time, experimental verification also further shows that the diffusion of hydrogen in boron nitride is extremely small, which is similar to VO x The Raman spectrum changes of the nanosheets indicate that the results are consistent.

[0185] Test Case 8

[0186] RUB-15 / VO x Raman Detection of Heterostructures in Hydrogen

[0187] First, the RUB-15 / VO prepared in step 2.3 of Preparation Example 1 was measured by Raman spectrometer. x Raman spectra of heterostructures. Before each measurement, ensure that the sample is placed stably on the sample stage of the Raman spectrometer and align the laser beam accurately to focus on the target area. The frequency range for measurement is set within the Raman active region (100cm -1 -3000cm -1 ) to ensure that all key Raman active peaks are captured.

[0188] Compared with 20nm-MXene / VO x In a similar hydrogen environment as the heterostructure test (200 °C, 3 hours), Raman fingerprints were collected to evaluate the diffusion of hydrogen through the RUB-15 zeolite membrane. Figure 5 (d) As shown in the lower left and right images, when exposed to hydrogen, VO x Located at 197cm -1 The peak area at 20 nm decreases rapidly in the RUB-15 zeolite encapsulation region, and the attenuation rate of the Raman signal is faster than that of the Raman signal through the artificial pore size 20 nm-MXene membrane. Therefore, the RUB-15 zeolite membrane based on intrinsic pores has a high permeability to hydrogen.

[0189] That is, in this test case, through VO x The Raman spectrum changes of the nanosheets indicate the presence of hydrogen that permeates the RUB-15 membrane, that is, the RUB-15 membrane can be used as a hydrogen permeation membrane; it also shows that VO x Nanosheets can be loaded on the surface of hydrogen separation membrane substrate as Raman indicators for monitoring hydrogen diffusion.

[0190] In some loads with VO x In the example of a two-dimensional film of nanosheets, VO x The changes in the Raman spectrum of the nanosheets can be used to determine whether hydrogen is penetrating into the two-dimensional film.

[0191] In some loads with VO x In the example of a two-dimensional film of nanosheets, VO x The changes in the Raman spectra of different areas of the nanosheet can be used to determine whether hydrogen is penetrating into the corresponding area of ​​the two-dimensional film, that is, the diffusion path of hydrogen can be displayed.

[0192] Here, the present invention demonstrates a strategy to monitor the penetration of hydrogen through a two-dimensional membrane using Raman spectroscopy. x The nanosheet indicator is loaded on the two-dimensional film, and the Raman spectrum measurement can show whether hydrogen permeates the two-dimensional film, as well as the area where hydrogen permeates.

[0193] Under the action of hydrogen, VO x The indicator changes from the M1 phase to the rutile phase at 197 cm -1 The attenuated Raman fingerprints are displayed at the surface, which can detect the transmission of gases through selective membranes based on different two-dimensional materials. For crystalline membranes based on non-porous nanosheets (such as boron nitride), vertical penetration is hindered. Roughness dependence studies on non-porous MXene membranes have shown that the disruption of nanosheet assembly is crucial to open interlayer pathways for hydrogen. At the same time, the diffusion of hydrogen in the vertical direction can be significantly enhanced by introducing artificial or inherent pores in the plane of the nanosheets. In summary, the scheme of the present invention can be used to reveal the pathways of hydrogen diffusion and guide the new design of efficient gas separation selective membranes.

[0194] The above content is a schematic description of the present invention and its implementation methods, which is not restrictive. What is shown in the embodiment is only one of the implementation methods of the present invention, and the actual implementation method is not limited thereto. Therefore, if a person of ordinary skill in the art is inspired by it and designs implementation methods and embodiments similar to the technical solution without creative design without departing from the purpose of the invention, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing vanadium oxide, characterized in that: The method comprises the steps of adopting a chemical vapor deposition method, in a mixed atmosphere formed by argon and hydrogen, using vanadium chloride and vanadium pentoxide as raw materials, growing at a temperature of 500°C±10°C for 5-15 minutes to obtain the vanadium oxide.

2. The method for preparing vanadium oxide according to claim 1, characterized in that: The vanadium pentoxide contains sodium chloride, and the mass of the sodium chloride accounts for 10-20% of the total mass of the vanadium pentoxide and the sodium chloride.

3. The method for preparing vanadium oxide according to claim 2, characterized in that: The volume ratio of argon to hydrogen in the mixed atmosphere formed by the argon and hydrogen is (1.8-2.2):

1.

4. The vanadium oxide obtained by the method for preparing vanadium oxide according to any one of claims 1 to 3, wherein the vanadium oxide has a molecular weight of 197±1 cm at an excitation wavelength of 532 nm. -1 Raman Peak.

5. A Raman indicator for detecting hydrogen diffusion, characterized in that: The Raman indicator comprises the vanadium oxide according to claim 4, and compared with not contacting with hydrogen, the Raman indicator is located at 197±1cm at an excitation wavelength of 532nm after contacting with hydrogen. -1 The Raman peak area at is reduced.

6. The Raman indicator for monitoring hydrogen diffusion according to claim 5, characterized in that: The vanadium oxide is a two-dimensional vanadium oxide film, and the thickness of the two-dimensional vanadium oxide film is 20 to 50 nm.

7. Use of the Raman indicator for monitoring hydrogen diffusion according to claim 5 or 6 in detecting hydrogen, characterized in that: include: Detecting the Raman spectrum of the Raman indicator that is not in contact with hydrogen at an excitation wavelength of 532 nm; contacting the Raman indicator with hydrogen at 150-250° C.; Detecting the Raman spectrum of the Raman indicator after contacting with hydrogen at an excitation wavelength of 532 nm; Compared with the case without contact with hydrogen, the Raman indicator is located at 197±1cm after contact with hydrogen. -1 The Raman peak area at is reduced.

8. A hydrogen separation membrane, characterized in that Include: Hydrogen separation membrane base membrane; and The Raman indicator according to claim 5 or 6; The Raman indicator is loaded on one side of the hydrogen separation membrane base film.

9. The hydrogen separation membrane according to claim 8, characterized in that The thickness of the hydrogen separation membrane base film is 20 to 100 nm; The Raman indicator is a two-dimensional film of vanadium oxide, and the thickness of the two-dimensional film of vanadium oxide is 20-50 nm.

10. The hydrogen separation membrane according to claim 8 or 9, characterized in that The hydrogen separation membrane base film is selected from one of Mxene and zeolite RUB-15 having pores with a diameter of 10 to 20 nm.

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