Nano vanadium oxide based on micro-cantilever, oxygen content regulation and preparation method

Abstract

The invention provides nano vanadium oxide based on a micro-cantilever, oxygen content regulation and control and a preparation method, the regulation and control method adopts a real-time quality monitoring function of the micro-cantilever to realize accurate regulation and control of the oxygen content in a vanadium oxide precursor material, and the change relation of the oxygen content reduction amount delta m of the vanadium oxide precursor material along with time or temperature is obtained; the preparation method comprises the following steps: coating a sample area at the free end of a micro-cantilever with a vanadium oxide precursor material, introducing H2S mixed gas according to the change relation of delta m along with time or temperature in a regulation and control method, controlling the temperature through a program of a heating element, monitoring the change of delta m in real time, and preparing nano vanadium oxide with target oxygen content when delta m reaches a preset target value. The oxygen content of the nano vanadium oxide can be accurately regulated and controlled, controllable preparation of a series of nano vanadium oxide with different oxygen contents is achieved, and dynamic monitoring and accurate regulation and control of the oxygen content of the nano vanadium oxide are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material preparation, and in particular relates to a nano vanadium oxide based on a micro cantilever beam, oxygen content control and a preparation method. Background Art

[0002] As a typical representative of transition metal oxide semiconductor materials, nano-vanadium oxide (VOx) has shown broad application prospects in energy storage and conversion, environmental governance, intelligent sensing and catalytic synthesis due to its unique electronic structure, adjustable energy band characteristics and rich redox activity. Studies have shown that the phase composition of nano-vanadium oxide (such as VO2, V2O3, V2O5, etc.) is directly related to its oxygen content, and a slight change in oxygen content will significantly affect the material's charge transfer characteristics, surface active site distribution and interface interaction with the target substance, ultimately determining its performance in specific application scenarios.

[0003] At present, the preparation technologies of nano vanadium oxide mainly include sol-gel method, hydrothermal method, combustion method and solution chemical method. For example, the sol-gel method can prepare nanostructured vanadium oxide on a large scale by reacting metal organic precursors with solvents, but the oxygen content of the product is limited by the coordination environment of the precursor, and the regulation range is limited; the hydrothermal method can synthesize VOx with specific morphology (such as nanowires and nanosheets) under high temperature and high pressure conditions, but the closed reaction system leads to a single means of regulating oxygen defects; although the combustion method can quickly obtain products with high crystallinity, it is difficult to achieve gradient regulation of oxygen content due to the violent exothermic process; the solution chemical method reduces vanadium-containing compounds to nano vanadium oxide through chemical reduction reactions, and the reductant regulation can prepare nanoparticles of different sizes and shapes, but there is a lack of systematic research on the fine control of oxygen content. The existing technology generally has the following defects: the existing preparation methods are mostly designed for a single phase (such as VO2 or V2O5), and usually can only prepare nano vanadium oxide with a fixed oxygen content. It is difficult to control the stoichiometric ratio of oxygen and vanadium in the product by optimizing the process parameters, and it is difficult to achieve continuous regulation of oxygen content by adjusting the same process parameters.

[0004] Different application scenarios have differentiated requirements for the oxygen content of nano-vanadium oxide. The existing preparation methods are insufficiently capable of regulating the oxygen content, which limits the optimization of material performance. It is urgent to develop a synthesis strategy with strong universality and controllable parameters, which can prepare nano-vanadium oxide with adjustable oxygen content and stable phase through the same technical path to meet the customized needs of multi-scenario applications. Summary of the invention

[0005] In view of the shortcomings of the prior art mentioned above, the purpose of the present invention is to provide a nano-vanadium oxide based on a micro-cantilever beam, an oxygen content regulation and a preparation method, which is used to solve the problem that it is difficult to achieve on-demand regulation of the oxygen content in nano-vanadium oxide in the prior art, and the problem that it is difficult to meet the preparation of a series of nano-vanadium oxides with different oxygen contents by one method.

[0006] To achieve the above-mentioned purpose and other related purposes, the present invention provides a method for regulating the oxygen content of nano-vanadium oxide based on a micro-cantilever beam, and the regulating method comprises the following steps:

[0007] S1. Provide a gas-solid reaction microreactor, the gas-solid reaction microreactor comprising a sealed cavity and a micro-cantilever located in the sealed cavity, the micro-cantilever is integrated with a heating element and a frequency signal reading element, the heating element is provided with a sample area, the heating element heats the sample by programmed temperature control, and the frequency signal reading element is used to monitor the resonant frequency of the micro-cantilever in real time;

[0008] S2, introducing H2S mixed gas into the sealed cavity, heating the heating element by programmed temperature control, recording the curve of the resonant frequency of the micro-cantilever beam changing with time or temperature, and using it as a baseline;

[0009] S3, coating the vanadium oxide precursor material on the sample area, setting the flow rate of the H2S mixed gas, the concentration of the H2S mixed gas, and the programmed temperature control of the heating element according to the same reaction conditions as step S2, and recording the curve of the change of the resonant frequency of the microcantilever beam over time or temperature;

[0010] S4, according to the change curves in steps S2 and S3, the relationship between the frequency change and time or temperature is obtained;

[0011] S5. According to Δm=Δf / S, the relationship between Δm and time or temperature is calculated. When Δm reaches the preset target value, the termination reaction signal is triggered, wherein Δf is the frequency change, S is the mass sensitivity of the microcantilever, and Δm is the reduction in oxygen content during the reduction of the vanadium oxide precursor material by H2S.

[0012] Preferably, an air inlet and an air outlet are provided on the sealed cavity, and the H2S mixed gas enters the sealed cavity through the air inlet, and the unreacted H2S is discharged as tail gas through the air outlet.

[0013] Preferably, an electrical adapter is provided on the sealed cavity, and the electrical adapter is used to achieve connection between the micro-cantilever beam and an external circuit.

[0014] Preferably, the flow rate of the H2S mixed gas introduced in step S2 is 1 mL / min to 100 mL / min, and the concentration of the H2S mixed gas is 0.01% to 100%, wherein the H2S mixed gas includes a mixture of H2S and a diluent gas, and the diluent gas includes argon or nitrogen.

[0015] Preferably, in step S2, the temperature at which the heating element heats the sample through programmed temperature control is no higher than 700° C., and the heating rate is 1° C. / min to 20° C. / min.

[0016] Preferably, the vanadium oxide precursor material in step S3 is a VOx nanomaterial, wherein x=1.5-2.5.

[0017] Preferably, the termination reaction signal in step S5 includes stopping the heating of the heating element or stopping the introduction of the H2S mixed gas into the sealed cavity.

[0018] The present invention also provides a method for preparing nano vanadium oxide, which adopts the above-mentioned method for controlling the oxygen content of nano vanadium oxide based on micro cantilever beam, and specifically comprises the following steps:

[0019] Coating a vanadium oxide precursor material on the sample area, and placing a micro cantilever beam coated with the vanadium oxide precursor material in the sealed cavity;

[0020] According to the same reaction conditions as step S2, the flow rate of the H2S mixed gas and the programmed temperature control of the heating element are set, the H2S mixed gas is introduced into the sealed cavity, the heating element performs programmed temperature control on the vanadium oxide precursor material, the resonant frequency change of the micro-cantilever beam is monitored in real time, and the reduction amount Δm of the oxygen content in the process of the vanadium oxide precursor material being reduced by H2S is calculated;

[0021] When Δm reaches a preset target value, a termination reaction signal is triggered to prepare nano-vanadium oxide with a target oxygen content.

[0022] The present invention also provides a nano vanadium oxide, which is prepared by adopting the above-mentioned method for preparing the nano vanadium oxide.

[0023] In addition, the present invention also provides a macro-scale preparation method of nano vanadium oxide, the preparation method comprising the following steps:

[0024] Placing the vanadium oxide precursor material in a reaction furnace;

[0025] A gas-solid reaction is carried out according to the gas-solid reaction parameters determined in the above-mentioned micro-cantilever-based method for controlling the oxygen content of nano-vanadium oxide, and the gas-solid reaction is terminated according to the temperature at which the heating element heats the vanadium oxide precursor material, thereby preparing nano-vanadium oxide with a corresponding oxygen content; wherein the gas-solid reaction parameters include the flow rate of the H2S mixed gas, the concentration of the H2S mixed gas, the heating rate at which the heating element heats the vanadium oxide precursor material through program temperature control, and the temperature at which the heating element heats the vanadium oxide precursor material.

[0026] The present invention also provides a nano vanadium oxide, which is prepared by adopting the above-mentioned macro-preparation method of nano vanadium oxide.

[0027] As described above, the nano-vanadium oxide, oxygen content control and preparation method based on micro-cantilever beam of the present invention have the following beneficial effects:

[0028] The present invention provides a method for preparing nano vanadium oxide capable of precisely controlling the oxygen content. The method utilizes the redox reaction between hydrogen sulfide gas and a vanadium oxide precursor material to carry out a gas-solid reaction in a gas-solid reaction microreactor, thereby realizing controllable preparation of a series of nano vanadium oxides with different oxygen contents, and realizing dynamic monitoring and precise control of the oxygen content of the nano vanadium oxide, thereby meeting the requirements for material performance in different application scenarios.

[0029] The present invention uses a micro cantilever beam integrated with a heating element and a frequency signal reading element as a reaction chamber to monitor in real time the mass change (i.e., the reduction in the oxygen content in the vanadium oxide precursor material) during the gas-solid reaction between the vanadium oxide precursor material and the hydrogen sulfide gas; when the reduction in the oxygen content reaches a preset target value, the reaction process can be terminated by stopping the heating or the introduction of the hydrogen sulfide atmosphere, thereby achieving precise control of the oxygen content in the nano vanadium oxide. In addition, the process parameters for preparing nano vanadium oxide obtained by the micro cantilever beam, such as the flow rate of the H2S mixed gas, the concentration of the H2S mixed gas, and the temperature and heating rate at which the heating element heats the vanadium oxide precursor material through program temperature control, can also be used in conventional equipment (tube furnace, etc.) with heating, ventilation and other functions to achieve large-scale preparation of nano vanadium oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of a gas-solid reaction microreactor in an embodiment of the present invention.

[0031] Figure 2 The graph shows the change in percentage of mass of the vanadium oxide precursor material with temperature measured in the method for controlling the oxygen content of nano-vanadium oxide based on a micro-cantilever in Example 1 of the present invention.

[0032] Figure 3Shown are the TEM images and XRD patterns of the V4O9 nanowires prepared in Example 2 of the present invention.

[0033] Figure 4 Shown are the TEM images and XRD patterns of the VO2 nanowires prepared in Example 3 of the present invention.

[0034] Figure 5 Shown are the TEM images and XRD patterns of the V2O3 nanowires prepared in Example 4 of the present invention.

[0035] Component number description

[0036] 10 Sealing chamber

[0037] 101 Air Inlet

[0038] 102 Exhaust port

[0039] 20 Microcantilever

[0040] 201 Heating element

[0041] 202 frequency signal reading element

[0042] 203 Sample Area DETAILED DESCRIPTION

[0043] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0044] Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are intended to describe specific embodiments, rather than to limit the scope of protection of the present invention. The test methods in the following examples without specifying specific conditions are generally carried out under conventional conditions or under conditions recommended by the manufacturers.

[0045] When the embodiments give numerical ranges, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art. In addition to the specific methods, equipment, and materials used in the embodiments, according to the grasp of the prior art by those skilled in the art and the record of the present invention, any methods, equipment, and materials of the prior art similar or equivalent to the methods, equipment, and materials described in the embodiments of the present invention can also be used to realize the present invention.

[0046] Please refer to the accompanying drawings. It should be noted that the diagrams provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, the diagrams only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout type may also be more complicated.

[0047] The present invention provides a method for controlling the oxygen content of nano-vanadium oxide based on a micro-cantilever beam, and the method comprises the following steps:

[0048] S1. Provide a gas-solid reaction microreactor, which includes a sealed cavity 10 and a micro-cantilever beam 20 located in the sealed cavity 10, wherein a heating element 201 and a frequency signal reading element 202 are integrated on the micro-cantilever beam 20, a sample area 203 is provided on the heating element 201, the heating element 201 heats the sample through program temperature control, and the frequency signal reading element 202 is used to monitor the resonant frequency of the micro-cantilever beam 20 in real time;

[0049] S2, introducing H2S mixed gas into the sealed cavity 10, heating the heating element 201 by program temperature control, recording the change curve of the resonant frequency of the micro cantilever beam 20 with time or temperature, and using it as a baseline;

[0050] S3, coating the vanadium oxide precursor material on the sample area 203, setting the flow rate of the H2S mixed gas, the concentration of the H2S mixed gas, and the program temperature control of the heating element 201 according to the same reaction conditions as step S2, and recording the change curve of the resonant frequency of the micro cantilever beam 20 over time or temperature;

[0051] S4, according to the change curves in steps S2 and S3, the relationship between the frequency change and time or temperature is obtained;

[0052] S5. According to Δm=Δf / S, the relationship between Δm and time or temperature is calculated. When Δm reaches the preset target value, a termination reaction signal is triggered, wherein Δf is the frequency change, S is the mass sensitivity of the micro cantilever beam 20, and Δm is the reduction in oxygen content during the reduction of the vanadium oxide precursor material by H2S.

[0053] First, execute step S1 to provide a gas-solid reaction microreactor, which includes a sealed cavity 10 and a micro-cantilever 20 located in the sealed cavity 10, wherein a heating element 201 and a frequency signal reading element 202 are integrated on the micro-cantilever 20, a sample area 203 is provided on the heating element 201, the heating element 201 heats the sample by programmed temperature control, and the frequency signal reading element 202 is used to monitor the resonant frequency of the micro-cantilever 20 in real time.

[0054] For details, see Figure 1 The micro cantilever 20 includes a root and a free end, a heating element 201 is integrated at the free end, a sample area 203 is provided on the heating element 201 for coating the sample, and the heating element 201 is used to heat the sample loaded at the free end of the micro cantilever 20; a frequency signal reading element 202 is integrated at the root for real-time monitoring of the resonant frequency of the micro cantilever 20.

[0055] As an example, an air inlet 101 and an air outlet 102 are provided on the sealed cavity 10 , and the H 2 S mixed gas enters the sealed cavity 10 through the air inlet 101 , and the unreacted H 2 S is discharged as tail gas through the air outlet 102 .

[0056] Specifically, the H 2 S mixed gas for gas-solid reaction with the sample flows into the sealed cavity 10 through the gas inlet 101 , and the unreacted gas is discharged as tail gas through the exhaust hole and passed into the gas washing bottle for collection.

[0057] As an example, an electrical transfer interface (not shown in the figure) is provided on the sealed cavity 10, and the electrical transfer interface is used to achieve the connection between the micro cantilever beam 20 and the external circuit.

[0058] Then, step S2 is performed, H2S mixed gas is introduced into the sealed cavity 10, the heating element 201 heats the sample through programmed temperature control, and the curve of the resonant frequency of the micro cantilever beam 20 changing with time or temperature is recorded and used as a baseline.

[0059] Specifically, for the micro-cantilever beam 20, the resonant frequency is its inherent vibration frequency in the free vibration state. When the micro-cantilever beam 20 is stimulated by the external environment, it will produce a significant vibration response near its resonant frequency. By monitoring the changes in the resonant frequency of the micro-cantilever beam 20, the changes in parameters such as the mass of the micro-cantilever beam 20 can be inferred.

[0060] The heating element 201 heats the sample at a certain heating rate, so that the temperature of the sample starts to rise from room temperature. In this step, the sample is not loaded in the sample area 203, that is, the heating of the heating element 201 is equivalent to the heating of the micro-cantilever 20. During the whole process, only the atmosphere and temperature of the micro-cantilever 20 change. The recorded curve of the change of the resonant frequency of the micro-cantilever 20 with the temperature is used as the baseline.

[0061] As an example, the flow rate of the H2S mixed gas in step S2 is 1 mL / min to 100 mL / min, and the concentration of the H2S mixed gas is 0.01% to 100%, wherein the H2S mixed gas includes a mixture of H2S and a diluent gas, and the diluent gas includes argon or nitrogen.

[0062] Specifically, the flow rate of the H2S mixed gas may include a value in any range of 1 mL / min, 5 mL / min, 10 mL / min, 20 mL / min, 40 mL / min, 60 mL / min, 80 mL / min, 100 mL / min, etc., and the concentration of the H2S mixed gas may include a value in any range of 0.01%, 0.1%, 1%, 5%, 10%, 50%, 80%, 90%, 100%, etc. Preferably, the concentration of the H2S mixed gas is 0.1% (the H2S mixed gas is a mixture of H2S and argon), and the flow rate of the H2S mixed gas is 20 ml / min.

[0063] As an example, in step S2, the temperature at which the heating element 201 heats the sample through program temperature control is no higher than 700° C., and the heating rate is 1° C. / min to 20° C. / min.

[0064] Specifically, the sample is usually heated from room temperature, the heating temperature is room temperature to 700°C, and the heating rate may include any value in the range of 1°C / min, 5°C / min, 10°C / min, 15°C / min, 20°C / min, etc.

[0065] Then, execute step S3, apply the vanadium oxide precursor material to the sample area 203, set the flow rate of the H2S mixed gas, the concentration of the H2S mixed gas, and the programmed temperature control of the heating element 201 according to the same reaction conditions as step S2, and record the change curve of the resonant frequency of the micro-cantilever beam 20 over time or temperature.

[0066] Specifically, the flow rate of the H2S mixed gas introduced in step S3, the concentration of the H2S mixed gas, and the heating rate of the heating element 201 for heating the vanadium oxide precursor material are the same as the conditions in step S2; the only difference between step S3 and step S2 is that in step S3, the vanadium oxide precursor material is coated on the sample area 203, and during the heating process of the heating element 201, the vanadium oxide precursor material undergoes a redox reaction (gas-solid reaction) with H2S, and the oxygen content in the vanadium oxide precursor material continues to decrease during the reaction. The smaller the mass of the load on the free end of the micro cantilever beam 20, the higher the resonant frequency.

[0067] As an example, the vanadium oxide precursor material in step S3 is a VOx nanomaterial, wherein x=1.5-2.5.

[0068] Specifically, when x=1.5, the vanadium oxide precursor material is V2O3; when x=2, the vanadium oxide precursor material is VO2; when x=2.5, the vanadium oxide precursor material is V2O5.

[0069] Then, step S4 is executed to obtain the relationship between the frequency variation and time or temperature according to the variation curves in steps S2 and S3.

[0070] Finally, execute step S5, and calculate the change relationship of Δm with time or temperature according to Δm=Δf / S. When Δm reaches the preset target value, trigger the termination reaction signal, wherein Δf is the frequency change, S is the mass sensitivity of the micro cantilever beam 20, and Δm is the reduction in oxygen content during the reduction of the vanadium oxide precursor material by H2S.

[0071] Specifically, according to the frequency change Δf and the mass sensitivity S of the micro cantilever 20, the reduction Δm of the oxygen content of the vanadium oxide precursor material during the H2S reduction process can be obtained, thereby obtaining the relationship between Δm and time or temperature, and the change of oxygen content in the vanadium oxide precursor material can be monitored in real time; wherein, the mass sensitivity S is a parameter of the micro cantilever itself, and its mass sensitivity can be calibrated after the micro cantilever is manufactured, and there is no excessive restriction on S here; m0 is the mass of the vanadium oxide precursor material loaded on the cantilever chip, and the mass change percentage of the vanadium oxide precursor material can be calculated as Δm / m0. As an example, the termination reaction signal in step S5 includes stopping the heating of the heating element 201 or stopping the introduction of the H2S mixed gas into the sealed cavity 10.

[0072] Specifically, the micro cantilever beam 20 is used to realize real-time monitoring of the oxygen content in the vanadium oxide precursor material. When the reduction in oxygen content reaches a preset target value, the gas-solid reaction of H2S and vanadium oxide can be terminated by stopping the heating of the heating element 201 or stopping the introduction of the H2S mixed gas, thereby achieving the control of the oxygen content in the nano vanadium oxide product to be prepared.

[0073] The present invention also provides a method for preparing nano vanadium oxide, which adopts the above-mentioned method for controlling the oxygen content of nano vanadium oxide based on the micro cantilever beam 20, and specifically comprises the following steps:

[0074] A1, coating a vanadium oxide precursor material on the sample area 203, and placing the micro cantilever beam 20 coated with the vanadium oxide precursor material in the sealed cavity 10;

[0075] A2. According to the same reaction conditions as step S2, the flow rate of the H2S mixed gas and the programmed temperature control of the heating element 201 are set, the H2S mixed gas is introduced into the sealed cavity 10, the heating element 201 performs programmed temperature control on the vanadium oxide precursor material, the resonant frequency change of the micro-cantilever beam 20 is monitored in real time, and the reduction amount Δm of the oxygen content in the process of the vanadium oxide precursor material being reduced by H2S is calculated;

[0076] A3. When Δm reaches a preset target value, a termination reaction signal is triggered to prepare nano-vanadium oxide with a target oxygen content.

[0077] Specifically, the flow rate of the H2S mixed gas, the concentration of the H2S mixed gas, and the programmed temperature control of the heating element 201 are set, and the relationship between Δm and time or temperature is obtained according to the nano-vanadium oxide oxygen content control method based on the micro-cantilever beam 20; in the specific embodiment of the present invention, based on the same vanadium oxide precursor material and reaction system, nano-vanadium oxide with different oxygen contents can be continuously prepared by adjusting the oxygen content reduction Δm. The preparation method of the present invention breaks through the limitation that the traditional method can only obtain a single phase in a single reaction.

[0078] The present invention also provides a nano vanadium oxide, which is prepared by adopting the above-mentioned preparation method of the nano vanadium oxide.

[0079] In addition, the present invention also provides a macro-scale preparation method of nano vanadium oxide, which comprises the following steps:

[0080] B1. placing a vanadium oxide precursor material in a reaction furnace;

[0081] B2. Carry out a gas-solid reaction according to the gas-solid reaction parameters determined in the above-mentioned method for controlling the oxygen content of nano-vanadium oxide based on the micro-cantilever beam 20, terminate the gas-solid reaction according to the temperature at which the heating element 201 heats the vanadium oxide precursor material, and thus prepare nano-vanadium oxide with a corresponding oxygen content; wherein the gas-solid reaction parameters include the flow rate of the H2S mixed gas, the concentration of the H2S mixed gas, the heating rate at which the heating element 201 heats the vanadium oxide precursor material through programmed temperature control, and the temperature at which the heating element 201 heats the vanadium oxide precursor material.

[0082] Specifically, the present invention applies the process parameters optimized by the micro-cantilever beam small-scale test to conventional equipment such as a tubular furnace, so as to achieve the reproduction of process parameters from the laboratory to large-scale production. According to the method for controlling the oxygen content of nano-vanadium oxide based on the micro-cantilever beam 20, the relationship between Δm and time or temperature is obtained. In large-scale preparation, according to the expected oxygen content in the nano-vanadium oxide to be prepared, the temperature at which the heating element 201 heats the vanadium oxide precursor material can be calculated according to the relationship between Δm and temperature. After heating to a predetermined temperature, the gas-solid reaction can be terminated, thereby realizing the large-scale preparation of nano-vanadium oxide with a corresponding oxygen content, solving the pain point of unstable performance during scale-up production of traditional methods, and continuously preparing nano-vanadium oxide of different phases, breaking through the limitation that traditional methods can only obtain a single phase in a single reaction.

[0083] Specifically, the reaction furnace is a reaction furnace with heating and ventilation functions, including equipment such as a tubular furnace, and no excessive restrictions are made here.

[0084] The present invention also provides a nano vanadium oxide, which is prepared by adopting the above-mentioned macro-preparation method of nano vanadium oxide.

[0085] In order to better understand the nano vanadium oxide, the method for regulating the oxygen content of nano vanadium oxide based on micro cantilever 20 and the preparation method thereof in the present invention, the nano vanadium oxide, the method for regulating the oxygen content of nano vanadium oxide based on micro cantilever 20 and the preparation method thereof in the present invention are described below with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0086] The mass sensitivity S of the microcantilever used in the following examples is 0.5 Hz / pg.

[0087] Example 1

[0088] This embodiment provides a method for controlling the oxygen content of nano-vanadium oxide based on a micro-cantilever beam, and the method comprises the following steps:

[0089] S1. Provide a gas-solid reaction microreactor, which includes a sealed cavity 10 and a micro-cantilever beam 20 located in the sealed cavity 10, wherein a heating element 201 and a frequency signal reading element 202 are integrated on the micro-cantilever beam 20, wherein a sample area 203 is provided on the heating element 201, wherein the heating element 201 heats the sample by program temperature control, and the frequency signal reading element 202 is used to monitor the resonant frequency of the micro-cantilever beam 20 in real time; an electrical adapter is provided on the sealed cavity 10, wherein the electrical adapter is connected to an external circuit to realize the connection between the micro-cantilever beam 20 and the external circuit;

[0090] S2. The sealed cavity 10 is provided with an air inlet 101 and an exhaust port 102. The H2S mixed gas enters the sealed cavity 10 through the air inlet 101, and the unreacted H2S is discharged as tail gas through the exhaust port 102. A H2S mixed gas with a concentration of 0.1% (the H2S mixed gas is a mixture of H2S and argon) is introduced into the sealed cavity 10 at a flow rate of 20 ml / min. The heating element 201 heats the sample from room temperature to 600°C through program temperature control at a heating rate of 10°C / min. The curve of the change of the resonant frequency of the micro-cantilever beam 20 with temperature is recorded and used as a baseline.

[0091] S3, coating the V2O5 nanomaterial on the sample area 203, setting the flow rate of the H2S mixed gas and the program temperature control of the heating element 201 according to the same reaction conditions as step S2, and recording the curve of the resonant frequency of the micro cantilever beam 20 changing with the temperature;

[0092] S4, according to the change curves in steps S2 and S3, the relationship between the frequency change and time or temperature is obtained;

[0093] S5. According to Δm=Δf / S, the relationship between Δm and temperature is calculated. When Δm reaches the preset target value, the heating element 201 is stopped from heating or the H2S mixed gas is stopped from being introduced into the sealed cavity 10 to terminate the reaction. The mass change percentage of the V2O5 nanomaterial is Δm / m0, where m0 is the mass of the V2O5 nanomaterial loaded on the micro cantilever beam 20. The relationship between Δm / m0 and temperature is calculated. Figure 2 .

[0094] See also Figure 2 This is a curve of the percentage change in mass of V2O5 nanomaterials versus temperature measured in the method for controlling the oxygen content of nano-vanadium oxide based on the micro-cantilever beam 20 of this embodiment. It can be seen from the figure that when the oxygen content of the V2O5 nanomaterial is reduced by about 4.3wt%, the corresponding temperature is 300°C, and the reaction is terminated by stopping the heating of the heating element 201 or stopping the introduction of the H2S mixed gas into the sealed cavity 10; when the oxygen content of the V2O5 nanomaterial is reduced by about 8.7wt%, the corresponding temperature is 350°C, and the reaction is terminated by stopping the heating of the heating element 201 or stopping the introduction of the H2S mixed gas into the sealed cavity 10; when the oxygen content of the V2O5 nanomaterial is reduced by about 16.9wt%, the corresponding temperature is 600°C, and the reaction is terminated by stopping the heating of the heating element 201 or stopping the introduction of the H2S mixed gas into the sealed cavity 10.

[0095] Example 2

[0096] This embodiment provides a method for preparing nano vanadium oxide, which is prepared by using the method for controlling the oxygen content of nano vanadium oxide based on a micro cantilever beam in Embodiment 1, and specifically comprises the following steps:

[0097] A1, coating the V2O5 nanomaterial on the sample area 203, and placing the micro cantilever beam 20 coated with the V2O5 nanomaterial in the sealed cavity 10;

[0098] A2, introducing H2S mixed gas with a concentration of 0.1% (H2S mixed gas is a mixture of H2S and argon) into the sealed cavity 10, the flow rate of the H2S mixed gas is 20ml / min, the heating element 201 heats the sample from room temperature through program temperature control, the heating rate is 10℃ / min, the resonant frequency change of the micro cantilever 20 is monitored in real time, and the reduction amount Δm of the oxygen content in the process of the V2O5 nanomaterial being reduced by H2S is calculated, m0 is the mass of the V2O5 nanomaterial loaded on the micro cantilever 20, and then the mass change percentage of the V2O5 nanomaterial is calculated as Δm / m0;

[0099] A3. When Δm / m0 reaches 4.3wt%, the heating of the heating element 201 is stopped or the introduction of the H2S mixed gas into the sealed cavity 10 is stopped to terminate the reaction. At this time, the temperature of the V2O5 nanomaterial is 300°C, and nano V4O9 is prepared.

[0100] This embodiment also provides a nano-vanadium oxide, which is prepared by the preparation method of the nano-vanadium oxide in this embodiment, and the nano-vanadium oxide is a V4O9 nanowire. Figure 3 TEM photos and XRD patterns of V4O9 nanowires. It can be seen from the figure that the prepared V4O9 has a one-dimensional nanowire morphology and the surface of the nanowire is rough; the XRD spectrum confirms that its main phase is V4O9.

[0101] Example 3

[0102] This embodiment provides a method for preparing nano vanadium oxide, which is prepared by using the method for controlling the oxygen content of nano vanadium oxide based on a micro cantilever beam in Embodiment 1, and specifically comprises the following steps:

[0103] A1, coating the V2O5 nanomaterial on the sample area 203, and placing the micro cantilever beam 20 coated with the V2O5 nanomaterial in the sealed cavity 10;

[0104] A2, introducing H2S mixed gas with a concentration of 0.1% (H2S mixed gas is a mixture of H2S and argon) into the sealed cavity 10, the flow rate of the H2S mixed gas is 20ml / min, the heating element 201 heats the sample from room temperature through program temperature control, the heating rate is 10℃ / min, the resonant frequency change of the micro cantilever 20 is monitored in real time, and the reduction amount Δm of the oxygen content in the process of the V2O5 nanomaterial being reduced by H2S is calculated, m0 is the mass of the V2O5 nanomaterial loaded on the micro cantilever 20, and then the mass change percentage of the V2O5 nanomaterial is calculated as Δm / m0;

[0105] A3. When Δm / m0 reaches 8.7 wt%, the heating of the heating element 201 is stopped or the introduction of the H2S mixed gas into the sealed cavity 10 is stopped to terminate the reaction. At this time, the temperature of the V2O5 nanomaterial is 350° C., and nano VO2 is prepared.

[0106] This embodiment also provides a nano-vanadium oxide, which is prepared by the preparation method of the nano-vanadium oxide in this embodiment, and the nano-vanadium oxide is VO2 nanowire. Figure 4 The TEM photo and XRD spectrum of VO2 nanowires show that the prepared VO2 has a one-dimensional nanowire morphology and the surface of the nanowire is rough; the XRD spectrum confirms that its main phase is VO2.

[0107] Example 4

[0108] This embodiment provides a method for preparing nano vanadium oxide, which is prepared by using the method for controlling the oxygen content of nano vanadium oxide based on a micro cantilever beam in Embodiment 1, and specifically comprises the following steps:

[0109] A1, coating the V2O5 nanomaterial on the sample area 203, and placing the micro cantilever beam 20 coated with the V2O5 nanomaterial in the sealed cavity 10;

[0110] A2, introducing H2S mixed gas with a concentration of 0.1% (H2S mixed gas is a mixture of H2S and argon) into the sealed cavity 10, the flow rate of the H2S mixed gas is 20ml / min, the heating element 201 heats the sample from room temperature through program temperature control, the heating rate is 10℃ / min, the resonant frequency change of the micro cantilever 20 is monitored in real time, and the reduction amount Δm of the oxygen content in the process of the V2O5 nanomaterial being reduced by H2S is calculated, m0 is the mass of the V2O5 nanomaterial loaded on the micro cantilever 20, and then the mass change percentage of the V2O5 nanomaterial is calculated as Δm / m0;

[0111] A3. When Δm / m0 reaches 16.9wt%, the heating of the heating element 201 is stopped or the introduction of the H2S mixed gas into the sealed cavity 10 is stopped to terminate the reaction. At this time, the temperature of the V2O5 nanomaterial is 350°C, and nano V2O3 is prepared.

[0112] This embodiment also provides a nano-vanadium oxide, which is prepared by the preparation method of the nano-vanadium oxide in this embodiment, and the nano-vanadium oxide is a V2O3 nanowire. Figure 5 TEM photos and XRD patterns of V2O3 nanowires. It can be seen from the figure that the prepared V2O3 has a one-dimensional nanowire morphology and the surface of the nanowire is smooth; the XRD pattern confirms that its main phase is V2O3.

[0113] Examples 2 to 4 are based on the same vanadium oxide precursor material (V2O5 nanomaterial) and reaction system. By adjusting the reduction in oxygen content (or the mass change percentage of the V2O5 nanomaterial is Δm / m0), nano V4O9, VO2, and V2O3 with different oxygen contents can be continuously prepared, breaking through the limitation that traditional methods can only obtain a single phase in a single reaction.

[0114] Example 5

[0115] This embodiment provides a nano-vanadium oxide and a macro-scale preparation method thereof, wherein the macro-scale preparation method comprises the following steps:

[0116] B1. Place V2O5 nanomaterials in a tube furnace;

[0117] B2. Carry out gas-solid reaction according to the gas-solid reaction parameters determined in the method for controlling the oxygen content of nano-vanadium oxide based on the micro-cantilever beam 20 in Example 1, and prepare nano-V4O9 when the temperature of the heating element 201 rises to 300°C; wherein the gas-solid reaction parameters include a flow rate of 20 ml / min for introducing an H2S mixed gas, a concentration of 0.1% of an H2S mixed gas (the H2S mixed gas is a mixture of H2S and argon), and a heating rate of 10°C / min for heating the V2O5 nanomaterial by the heating element 201 through program temperature control.

[0118] In summary, the present invention provides a method for preparing nano vanadium oxide that can accurately control the oxygen content, utilizing the redox reaction between hydrogen sulfide gas and vanadium oxide precursor material, performing gas-solid reaction in a gas-solid reaction microreactor, and realizing a series of controllable preparations of nano vanadium oxides with different oxygen contents, realizing dynamic monitoring and precise control of the oxygen content of nano vanadium oxide, and meeting the requirements of different application scenarios for material performance. The present invention uses a micro cantilever beam integrated with a heating element and a frequency signal reading element as a reaction chamber, and monitors in real time the mass change (i.e., the reduction in oxygen content in the vanadium oxide precursor material) during the gas-solid reaction of the vanadium oxide precursor material and hydrogen sulfide gas; when the reduction in oxygen content reaches a preset target value, the heating or the introduction of hydrogen sulfide atmosphere can be stopped to achieve the effect of terminating the reaction process, thereby realizing precise control of the oxygen content in the nano vanadium oxide. In addition, the process parameters for preparing nano-vanadium oxide obtained by the micro-cantilever beam, such as the flow rate of the H2S mixed gas, the concentration of the H2S mixed gas, and the temperature and heating rate of the vanadium oxide precursor material heated by the heating element through program temperature control, can also be used for conventional equipment (tube furnace, etc.) with heating and ventilation functions to achieve large-scale preparation of nano-vanadium oxide. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0119] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for controlling the oxygen content of nano-vanadium oxide based on a micro-cantilever beam, characterized in that: The control method comprises the following steps: S1. Provide a gas-solid reaction microreactor, the gas-solid reaction microreactor comprising a sealed cavity and a micro-cantilever located in the sealed cavity, the micro-cantilever is integrated with a heating element and a frequency signal reading element, the heating element is provided with a sample area, the heating element heats the sample by programmed temperature control, and the frequency signal reading element is used to monitor the resonant frequency of the micro-cantilever in real time; S2, introducing H2S mixed gas into the sealed cavity, heating the heating element by programmed temperature control, recording the curve of the resonant frequency of the micro-cantilever beam changing with time or temperature, and using it as a baseline; S3, coating the vanadium oxide precursor material on the sample area, setting the flow rate of the H2S mixed gas, the concentration of the H2S mixed gas, and the programmed temperature control of the heating element according to the same reaction conditions as step S2, and recording the curve of the change of the resonant frequency of the microcantilever beam over time or temperature; S4, according to the change curves in steps S2 and S3, the relationship between the frequency change and time or temperature is obtained; S5. According to Δm=Δf / S, the relationship between Δm and time or temperature is calculated. When Δm reaches the preset target value, the termination reaction signal is triggered, wherein Δf is the frequency change, S is the mass sensitivity of the microcantilever, and Δm is the reduction in oxygen content during the reduction of the vanadium oxide precursor material by H2S.

2. The method for controlling the oxygen content of nano-vanadium oxide based on micro-cantilever beam according to claim 1, characterized in that: The sealed cavity is provided with an air inlet and an air outlet. The H2S mixed gas enters the sealed cavity through the air inlet, and the unreacted H2S is discharged as tail gas through the air outlet.

3. The method for controlling the oxygen content of nano-vanadium oxide based on micro-cantilever beam according to claim 1, characterized in that: The sealed cavity is provided with an electrical transfer interface, and the electrical transfer interface is used to realize the connection between the micro cantilever beam and an external circuit.

4. The method for controlling the oxygen content of nano-vanadium oxide based on micro-cantilever according to claim 1, characterized in that: In step S2, the flow rate of the H2S mixed gas is 1 mL / min to 100 mL / min, and the concentration of the H2S mixed gas is 0.01% to 100%, wherein the H2S mixed gas includes a mixture of H2S and a diluent gas, and the diluent gas includes argon or nitrogen.

5. The method for controlling the oxygen content of nano-vanadium oxide based on micro-cantilever according to claim 1, characterized in that: In step S2, the temperature at which the heating element heats the sample through programmed temperature control is no higher than 700° C., and the heating rate is 1° C. / min to 20° C. / min.

6. The method for controlling oxygen content of nano-vanadium oxide based on micro-cantilever according to claim 1, characterized in that: The vanadium oxide precursor material in step S3 is a VOx nanomaterial, wherein x=1.5-2.

5.

7. The method for controlling the oxygen content of nano-vanadium oxide based on micro-cantilever beam according to claim 1, characterized in that: The termination reaction signal in step S5 includes stopping the heating of the heating element or stopping the introduction of the H2S mixed gas into the sealed cavity.

8. A method for preparing nano vanadium oxide, characterized in that: The preparation method is prepared by the method for controlling the oxygen content of nano-vanadium oxide based on a micro-cantilever beam as described in any one of claims 1 to 7, and specifically comprises the following steps: Coating a vanadium oxide precursor material on the sample area, and placing a micro cantilever beam coated with the vanadium oxide precursor material in the sealed cavity; According to the same reaction conditions as step S2, the flow rate of the H2S mixed gas and the programmed temperature control of the heating element are set, the H2S mixed gas is introduced into the sealed cavity, the heating element performs programmed temperature control on the vanadium oxide precursor material, the resonant frequency change of the micro-cantilever beam is monitored in real time, and the reduction amount Δm of the oxygen content in the process of the vanadium oxide precursor material being reduced by H2S is calculated; When Δm reaches a preset target value, a termination reaction signal is triggered to prepare nano-vanadium oxide with a target oxygen content.

9. A nano vanadium oxide, characterized in that: The nano vanadium oxide is prepared by the method for preparing the nano vanadium oxide according to claim 8.

10. A method for preparing nano vanadium oxide in large quantities, characterized in that: The preparation method comprises the following steps: Placing the vanadium oxide precursor material in a reaction furnace; A gas-solid reaction is carried out according to the gas-solid reaction parameters determined in the method for controlling the oxygen content of nano-vanadium oxide based on a micro-cantilever beam as described in any one of claims 1 to 7, and the gas-solid reaction is terminated according to the temperature at which the vanadium oxide precursor material is heated by the heating element, thereby preparing nano-vanadium oxide with a corresponding oxygen content; wherein the gas-solid reaction parameters include the flow rate of the H2S mixed gas, the concentration of the H2S mixed gas, the heating rate at which the heating element heats the vanadium oxide precursor material through program temperature control, and the temperature at which the heating element heats the vanadium oxide precursor material.

11. A nano vanadium oxide, characterized in that: The nano vanadium oxide is prepared by the macro-scale preparation method of nano vanadium oxide according to claim 10.

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