CN111988872A - Palladium nanosheet/graphene-based fiber membrane and preparation method thereof - Google Patents
Palladium nanosheet/graphene-based fiber membrane and preparation method thereof Download PDFInfo
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
- H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
- H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
- H05B3/34—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater flexible, e.g. heating nets or webs
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- Carbon And Carbon Compounds (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention provides a preparation method of a palladium nanosheet/graphene-based fiber membrane, which comprises the following steps: preparing a pre-stripping dispersion liquid of palladium powder, preparing a mixture of the palladium powder and graphene oxide, preparing a palladium nanosheet/graphene oxide dispersion liquid, spinning and post-treating. According to the preparation method of the palladium nanosheet/graphene-based fiber membrane, graphene oxide is added in the preparation process of the palladium nanosheet, so that the palladium powder can be assisted to be stripped into the palladium nanosheet, and the palladium nanosheet and the graphene oxide can be uniformly mixed. In the spinning process, palladium nanosheets, graphene and carbon black are further loaded on the fibers, and the fiber has the advantages of being large in specific surface area, strong in infrared radiation, high in thermal conductivity, good in flexibility, remarkable in bending resistance effect and the like. The invention also provides a palladium nanosheet/graphene-based fiber membrane.
Description
Technical Field
The invention relates to the technical field of graphene heating devices, in particular to a graphene electrostatic spinning fiber membrane technology, and more particularly relates to a preparation method of a flexible palladium nanosheet/graphene-based fiber membrane.
Background
Graphene is a two-dimensional nanomaterial with a hexagonal honeycomb lattice structure formed by carbon atoms through sp2 hybrid orbitals and only one layer of carbon atoms thick. The unique structure of graphene gives it a number of excellent properties, such as a high theoretical specific surface area (2630 m)2The material is prepared by the following raw materials, such as the raw materials of the material are selected from the following raw materials, such as/g), ultrahigh electron mobility (200000 cm2/v.s), high thermal conductivity (5300W/m.K), high Young modulus (1.0TPa), high light transmittance (97.7%) and the like. By virtue of the advantages of the structure and the performance of the graphene, the graphene has a huge application prospect in the fields of energy storage and conversion devices, nano-electronic devices, multifunctional sensors, flexible wearable electronics, electromagnetic shielding, corrosion prevention and the like. In view of the flexibility and the conductive characteristic of graphene, the graphene slurry is added into the printing ink to prepare the conductive printing ink, and the graphene heating layer is further prepared by spraying and drying the printing ink to prepare the graphene heating body.
Along with the trend of people to good and healthy life, the traditional heating system is improved, more economic and clean alternative energy is searched, and the development of a novel green low-carbon heating system is reluctant. An electric heating technology based on graphene infrared emission performance (far infrared rays with the wavelength of 5-14 microns), namely graphene-based infrared heating ink and an infrared heating body technology thereof, provides an effective solution for solving the problems. Compared with the traditional heating methods such as coal burning, steam, hot air and resistance, the graphene heating method has the advantages of high heating speed, high electricity-heat conversion rate, automatic temperature control, zone control, stable heating, no abnormal sound in the heating process, high heat conduction efficiency, low operation cost (the power consumption of each square meter of the graphene electrothermal film can be reduced to 0.5 degree every day), relatively uniform heating, small floor area, low investment and production cost, long service life, high working efficiency and the like, and is more favorable for popularization and application. The energy-saving heating device replaces the traditional heating device, has particularly remarkable electricity-saving effect, can generally save electricity by about 30 percent, and even can reach 60 to 70 percent in individual occasions.
In the prior art, graphene is generally prepared into graphene slurry, ink or paint, and then prepared into a graphene heating coating and the like through a printing method. For example, patent application No. CN 201911401440.7, the patent name of which is graphene far infrared heating brick, discloses a graphene far infrared heating brick, a brick unit of the floor heating brick comprises a heating element and a heat dissipation member, wherein the heating element is made of graphene composite coating, and the heat dissipation member is made of graphene composite rack. The graphene heating coating is printed on the base material, and the graphene heating coating prepared by printing is easily broken and degummed after being repeatedly folded and stretched, so that the graphene heating coating is broken to influence the heat production effect and the service life of the graphene heating coating. In addition, the defects that the graphene heating coating has poor adhesion effect with a flexible substrate and is easy to separate after being used for a long time are still the subject of the industry.
The graphene fiber membrane is prepared by adding graphene into a spinning solution and further using an electrostatic spinning technology, has the advantages of strong flexibility, good bending resistance effect, large surface area and the like, does not need to be attached to a substrate, and can be independently formed into a membrane or bonded on the flexible substrate through an adhesive for heat supply after the membrane is formed. However, the existing graphene fiber membrane has the following defects: (1) the dispersion effect is poor, and the graphene flakes are easy to stack with each other, so that the concentration of local graphene is too high, and the fibers cannot be spun; (2) the resistance value is large, and the graphene fiber membrane with low resistance value are difficult to prepare through single graphene spinning; (3) poor heat resistance and easy melt deformation at higher temperature.
Disclosure of Invention
In view of the above, the invention provides a preparation method of a palladium nanosheet/graphene-based fiber film, and the invention also provides a palladium nanosheet/graphene-based fiber film prepared by the preparation method of the palladium nanosheet/graphene-based fiber film, so as to solve the defects that the existing/graphene-based fiber film is poor in dispersion effect, large in resistance value, low in conductivity, poor in heat resistance and the like, and graphene flakes are easy to stack mutually.
In a first aspect, the invention provides a preparation method of a palladium nanosheet/graphene-based fiber membrane, which comprises the following steps:
preparing a pre-stripping dispersion of palladium powder: providing palladium powder and adding the palladium powder into the pre-stripping dispersion liquid, performing primary water bath ultrasound on the pre-stripping dispersion liquid added with the palladium powder, wherein the temperature of the primary water bath ultrasound is 5-15 ℃, and centrifuging and collecting supernatant after the primary water bath ultrasound is finished to prepare the pre-stripping dispersion liquid of the palladium powder;
preparing a mixture of palladium powder and graphene oxide: adding graphene oxide into a pre-stripping dispersion liquid of palladium powder, performing secondary water bath ultrasound at the temperature of 5-15 ℃, centrifuging after the secondary water bath ultrasound is finished, collecting a bottom layer mixture, dispersing the bottom layer mixture in water, washing and drying to obtain a mixture of the palladium powder and the graphene oxide;
preparing a palladium nanosheet/graphene oxide dispersion liquid: dispersing a mixture of palladium powder and graphene oxide in DMF to prepare a mixed solution, performing ultrasonic treatment on the mixed solution by using a pulse probe at the ultrasonic temperature of 5-15 ℃, and concentrating the mixed solution after the ultrasonic treatment is finished to prepare a palladium nanosheet/graphene oxide dispersion solution;
spinning: adding carbon black and PAN powder into a palladium nanosheet/graphene oxide dispersion liquid, uniformly stirring, and then carrying out three-stage water bath ultrasound, wherein the temperature of the three-stage water bath ultrasound is 5-15 ℃, and after the three-stage water bath ultrasound is finished, the three-stage water bath ultrasound is used as a spinning stock solution, and electrostatic spinning and collection are carried out by using a spinning needle with the inner diameter increased along a filament outlet direction, so as to prepare the palladium nanosheet/graphene oxide hybrid porous fibrous membrane;
and (3) post-treatment: washing the palladium nanosheet/graphene oxide hybrid porous fiber membrane, drying and reducing to obtain a palladium nanosheet/graphene-based fiber membrane;
the mass of the graphene oxide is 0.5-5 times of the mass of the palladium powder in the pre-stripping dispersion liquid of the palladium powder, the mass fraction of PAN in the spinning stock solution is 8-12%, and the pre-stripping dispersion liquid is isopropanol, deionized water or a mixed solution of the isopropanol and the deionized water.
The preparation method of the palladium nanosheet/graphene-based fibrous membrane comprises the steps of preparing a pre-stripping dispersion liquid of palladium powder, preparing a mixture of the palladium powder and graphene oxide, preparing the palladium nanosheet/graphene oxide dispersion liquid, spinning and post-treating. The step of preparing the pre-stripping dispersion liquid of the palladium powder can strip the palladium powder in advance, and the stripping efficiency of the palladium powder and the preparation efficiency of the palladium nanosheets are improved by collecting the preliminarily stripped palladium powder and using the palladium powder for the next stripping. In the step of preparing the mixture of the palladium powder and the graphene oxide, the preliminarily peeled palladium powder and the graphene oxide are subjected to water bath ultrasound together, the palladium powder has poor dispersibility in the pre-peeling dispersion liquid, the graphene is added into the pre-peeling dispersion liquid of the palladium powder and the water bath ultrasound is carried out together, and the palladium powder is effectively peeled and can be well mixed with the graphene oxide with the aid of the graphene. In the step of preparing the palladium nanosheet/graphene oxide dispersion liquid, the mixed liquid is subjected to ultrasonic treatment by adopting a pulse probe, so that the palladium nanosheet can be effectively prepared, and the palladium nanosheet and the graphene oxide dispersion liquid are further mixed, so that the phenomenon that the palladium nanosheet or the graphene oxide is stacked mutually to cause that the local concentration is too high and cannot be spun is prevented, and the conductivity and the dispersion uniformity among graphene sheet layers can be improved. The primary water bath ultrasound, the secondary water bath ultrasound and the pulse probe ultrasound are carried out at low temperature, so that the prepared palladium nanosheet can be effectively prevented from being degraded. In the spinning step, PAN powder and carbon black are added into a DMF solution, three-stage water bath ultrasound is performed after uniform stirring, the spinning solution is more uniform through the stirring and ultrasound processes, the uniformity of the physical size and the performance of the produced filament is ensured, the carbon black and the PAN powder can be fully dispersed in the palladium nanosheet/graphene oxide dispersion liquid, the uniform distribution and the uniform conductivity of the electric conductor of the spinning fiber are ensured, the electric conductor is fully doped on the PAN high molecular compound, and the palladium nanosheet/graphene oxide hybrid porous fiber with uniform conductivity is prepared. In the post-treatment step, the palladium nanosheet/graphene oxide hybrid porous fiber membrane is washed, dried and reduced, and the graphene oxide is reduced into reduced graphene oxide, so that the reduced palladium nanosheet/graphene-based fiber membrane is prepared, and has the advantages of stable chemical property, heat resistance, strong electric conductivity, high infrared radiance, integration of heat collecting property and photo-thermal property and the like.
According to the preparation method of the palladium nanosheet/graphene-based fiber membrane, graphene oxide is added in the preparation process of the palladium nanosheet, so that the palladium powder can be assisted to be stripped into the palladium nanosheet, and the palladium nanosheet and the graphene oxide can be uniformly mixed. The palladium nanosheet, the graphene oxide and the carbon black are further loaded on the fiber in the spinning process, so that the fiber has the advantages of large specific surface area, strong infrared radiation, remarkable electrothermal and photothermal properties, high thermal conductivity, good flexibility, remarkable bending-resistant effect and the like, and the fiber also has the advantages of high mechanical strength, medium-high temperature resistance and the like due to the fact that a large amount of PAN (polyacrylonitrile) polymers are contained in the fiber.
Preferably, in the step of preparing the pre-stripping dispersion liquid of the palladium powder, the mass-volume ratio of the palladium powder to the pre-stripping dispersion liquid is 10-500 mg/ml, the power of the primary water bath ultrasound is 250-500W, and the time of the primary water bath ultrasound is 24-72 h;
the rotating speed of the centrifugation is 1500-3500 RPM, and the time of the centrifugation is 5-30 min. The function of pre-stripping the palladium simple substance can be achieved through primary water bath ultrasound, the subsequent centrifugal process can separate the pre-stripped few-layer palladium simple substance from un-stripped palladium powder, the small palladium simple substance generated by pre-stripping is transferred to the next stripping procedure, and the few-layer palladium nanosheet is efficiently prepared.
Preferably, in the step of preparing the mixture of palladium powder and graphene oxide, the power of the secondary water bath ultrasound is 250-500W, and the time of the secondary water bath ultrasound is 8-24 h;
the rotating speed of the centrifugation is 8000-15000 RPM, and the time of the centrifugation is 20-100 min. After adding the graphene oxide, mixing the graphene oxide with the preliminarily peeled palladium powder, further performing secondary water bath ultrasound, mixing the graphene oxide with the preliminarily peeled palladium powder, wherein the graphene oxide has the effect of assisting the peeling and dispersion of the palladium powder, and preventing the palladium nanosheets and the graphene oxide from being stacked mutually. And further collecting the palladium nanosheets and graphene oxide generated by stripping through centrifugation for subsequent steps.
Preferably, in the step of preparing the mixture of palladium powder and graphene oxide, the mixture of the bottom layer is dispersed in water for washing, then the solvent is concentrated and removed by using a rotary evaporation method, and the concentrated mixture is transferred to a temperature of 30-40 ℃ for vacuum drying for 2-8 hours to prepare the mixture of the palladium powder and the graphene oxide. The method has the advantages that the residual pre-stripping dispersion liquid on the mixture of the palladium powder and the graphene oxide can be effectively removed through the steps of removing the solvent by rotary evaporation, drying in vacuum and the like, the subsequent steps of preparing the palladium nanosheet/graphene oxide dispersion liquid and spinning are facilitated, the spinnability of the spinning solution is improved, and meanwhile, the concentration of the palladium nanosheet/graphene oxide dispersion liquid is conveniently measured.
Preferably, in the step of preparing the palladium nanosheet/graphene oxide dispersion liquid, the mass-to-volume ratio of the mixture of the palladium powder and the graphene oxide to the DMF is 1-10 mg/ml, the ultrasonic time of the pulse probe is 2-12 h, the ultrasonic power of the pulse probe is 200-300W, and the ultrasonic frequency of the pulse probe is set as: ultrasound 5s, interval 5 s. Therefore, the mixture of palladium powder and graphene oxide can be promoted to be well dispersed in DMF through pulse probe ultrasound, so that a dispersion liquid with good dispersion of palladium nanosheets and graphene oxide is prepared, and preparation is made for preparing a spinning solution subsequently.
Preferably, in the step of preparing the palladium nanosheet/graphene oxide dispersion liquid, after the ultrasonic treatment is finished, the mixed liquid is concentrated by a vacuum rotary evaporation method until the solid content is 10-50 mg/ml;
the vacuum degree of the vacuum rotary evaporation method is 0.05-0.08 MPa, and the temperature of the vacuum rotary evaporation method is 55-65 ℃. The palladium nanosheet/graphene oxide dispersion liquid is prepared through two steps, namely the palladium nanosheet and the graphene oxide are firstly dispersed at low concentration and then concentrated to reach the high concentration required by spinning, so that the palladium nanosheet and the graphene oxide can be well dispersed in DMF, the conductive requirement of a fiber membrane can be met, the content of a conductive body in the palladium nanosheet/graphene-based fiber membrane can be effectively increased by concentrating the mixed liquid through a vacuum rotary evaporation method, and the conductivity of the fiber membrane is increased.
Preferably, in the spinning step, the mass-to-volume ratio of the carbon black to the palladium nanosheet/graphene oxide dispersion is 50-100 mg/ml;
the time of the three-stage water bath ultrasound is 4-12 hours, the power of the three-stage water bath ultrasound is 250-500W, and the collection is realized by collecting palladium nanosheets/graphene oxide hybrid porous fibers by adopting a collecting plate. The addition of the carbon black can further improve the conductivity of the palladium nanosheet/graphene-based fiber membrane, regulate and control the ratio of the carbon black to the palladium nanosheet/graphene oxide dispersion liquid, improve the conductivity of the palladium nanosheet/graphene-based fiber membrane, avoid the influence of excessive use of the carbon black on the spinnability of a spinning solution, and reduce the flexibility of the palladium nanosheet/graphene-based fiber membrane. The palladium nanosheet, the graphene oxide and the carbon black are further stripped and dispersed through three-stage water bath ultrasound to prepare a conductive body with a smaller size, so that the conductive body can be uniformly doped into the palladium nanosheet/graphene hybrid porous fiber, and the palladium nanosheet/graphene-based fiber membrane with good flexibility, high conductivity, excellent heat resistance and strong mechanical property is prepared.
Preferably, in the spinning step, the inner diameter of the thin end of the spinning needle head is 0.3mm, the inner diameter of the thick end of the spinning needle head is 0.36mm, the electrostatic spinning voltage is 20-50 KV, and the receiving distance is 10-30 cm. Therefore, through carrying out electrostatic spinning by using the spinning needle with the inner diameter increased along the filament outlet direction, the fluid velocity of the spinning stock solution forms sudden drop and generates outward component velocity along the radial direction, so that the palladium nanosheets and the graphene oxide are distributed along the radial direction, and the palladium nanosheets/graphene oxide hybrid porous fibers formed after curing have a large number of pore-shaped structures distributed along the radial direction, so that the palladium nanosheets/graphene oxide hybrid porous fibers have good radial flexibility and axial elasticity, and the palladium nanosheets/graphene oxide hybrid porous fiber membranes also have good flexibility and elasticity in all directions.
Preferably, in the post-treatment step, the palladium nanosheet/graphene oxide hybrid porous fiber membrane is washed by deionized water for 1-3 times, and the palladium nanosheet/graphene oxide hybrid porous fiber membrane is transferred to a vacuum drying oven at the temperature of 60-85 ℃ for drying for 4-12 hours;
soaking the dried palladium nanosheet/graphene oxide hybrid porous fiber membrane in HI and NaBH4And hydrazine hydrate and ascorbic acid, and preparing the palladium nanosheet/graphene-based fiber membrane. Removing residues in the palladium nanosheet/graphene-based fiber membrane through washing and drying processesAnd reserving DMF to prepare the PAN/palladium nanosheet/graphene oxide hybrid porous fiber membrane, wherein the washed and dried PAN/palladium nanosheet/graphene oxide hybrid porous fiber membrane has higher porosity, larger specific surface area and flexibility. And finally, the graphene oxide is reduced into reduced graphene oxide through a reduction process, and the reduced palladium nanosheet/graphene-based fiber membrane has better environmental stability and heat resistance, so that the service life of the palladium nanosheet/graphene-based fiber membrane is effectively prolonged.
In a second aspect, the invention further provides a palladium nanosheet/graphene-based fibrous membrane prepared by the preparation method of the palladium nanosheet/graphene-based fibrous membrane in the first aspect.
The palladium nanosheet/graphene-based fiber membrane has the advantages of high porosity, good flexibility, large specific surface area, high conductivity, high electrothermal conversion efficiency, high photo-thermal conversion rate, high infrared emissivity, high heat conduction efficiency and the like, and also has obvious sterilization and bacteriostasis effects. When the palladium nanosheet/graphene-based fiber membrane is applied to floor heating, physical therapy or clothes, the palladium nanosheet/graphene-based fiber membrane also has the effect of infrared physical therapy. The basic fiber material of the palladium nanosheet/graphene-based fiber membrane is Polyacrylonitrile (PAN), so that the palladium nanosheet/graphene-based fiber membrane has the advantages of high mechanical property, medium-high temperature resistance, difficulty in aging and the like. When the palladium nanosheet/graphene-based fiber film is applied to a heating device, the palladium nanosheet/graphene-based fiber film has the advantages of uniform heat generation, stable heating performance, high infrared emission performance, medium-high temperature resistance and the like, and is low in attenuation rate after long-time use.
Advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of the invention.
Drawings
In order to more clearly illustrate the contents of the present invention, a detailed description thereof will be given below with reference to the accompanying drawings and specific embodiments.
Fig. 1 is a test chart of photothermal conversion performance provided by the present invention (240s, which corresponds to example 4, comparative example 2, comparative example 3, and comparative example 1 in order from top to bottom).
Detailed Description
While the following is a description of the preferred embodiments of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
The following describes in detail the preparation method of the palladium nanosheet/graphene-based fibrous membrane and the prepared palladium nanosheet/graphene-based fibrous membrane by using specific examples, including examples and comparative examples (hereinafter referred to as "comparative examples"), which are set with reference to parameter ranges of example 4 for discussing the influence of each parameter on the performance of the palladium nanosheet/graphene-based fibrous membrane.
A preparation method of a palladium nanosheet/graphene-based fiber membrane comprises the following steps:
preparing a pre-stripping dispersion of palladium powder: palladium powder was provided and added to the pre-peeling dispersion, the type of pre-peeling dispersion (the pre-peeling dispersion in examples 7 and 8 was a mixed pre-peeling dispersion with a mass ratio of deionized water to isopropyl alcohol of 1: 1) and the concentration of palladium powder in the pre-peeling dispersion are shown in table 1. The pre-stripped dispersion added with palladium powder is subjected to primary water bath ultrasound, wherein the temperature (the primary water bath ultrasound is referred to as "one-pass" for short, the temperature here is a temperature value set by a water bath kettle, and the actual water bath temperature has a certain fluctuation), power and ultrasound time of the primary water bath ultrasound are shown in table 1. And after the ultrasonic treatment is finished, centrifuging the pre-stripping dispersion liquid added with the palladium powder, and collecting supernatant to prepare the pre-stripping dispersion liquid of the palladium powder, wherein the centrifugal rotating speed and the centrifugal time are shown in table 1.
TABLE 1 parameters of Pre-strip Dispersion procedure for preparation of Palladium powder
Preparing a mixture of palladium powder and graphene oxide: to the previously prepared pre-exfoliated dispersion of palladium powder, graphene oxide was added, where the ratio of the mass of graphene oxide to the mass of palladium powder in the supernatant (where palladium powder in the supernatant refers to the palladium powder dispersed in the supernatant, and the mass of palladium powder in the supernatant can be obtained by subtracting the mass of palladium powder centrifugally precipitated in the pre-exfoliation step from the mass of total palladium powder provided) is seen in table 2. After the addition of graphene oxide, the pre-exfoliated dispersion liquid of graphene oxide and palladium powder was transferred to a water bath kettle for secondary water bath ultrasound, wherein the temperature (referred to as "secondary ultrasound" for short) of the secondary water bath ultrasound, the power and the ultrasound time are shown in table 2. And after the secondary water bath ultrasound treatment is finished, centrifuging the pre-stripping dispersion liquid of the palladium powder added with the graphene oxide, and collecting a bottom layer mixture, wherein the centrifugal rotating speed and the centrifugal time are shown in table 2. And dispersing the bottom layer mixture in water, oscillating and washing the bottom layer mixture, transferring the washed mixture into a vacuum rotary evaporator for rotary evaporation to remove the pre-stripping dispersion liquid, transferring the rotary-evaporated mixture into a vacuum drying oven for drying, wherein the temperature and the drying time of the drying oven are shown in table 2.
TABLE 2 parameters of the procedure for preparing the mixture of palladium powder and graphene oxide
Preparing a palladium nanosheet/graphene oxide dispersion liquid: the mixture of palladium powder and graphene oxide was dispersed in DMF (N, N-dimethylformamide) to prepare a mixed solution, wherein the concentration of the mixture of palladium powder and graphene oxide (referred to as "mixture concentration") is shown in table 3. Performing ultrasound on a DMF solution of a mixture of palladium powder and graphene oxide by using a pulse probe, wherein the frequency of the pulse probe ultrasound is set as follows: ultrasound 5s, interval 5s, wherein the temperature of the pulse probe ultrasound (abbreviated as "pulse ultrasound"), the power of the pulse probe ultrasound, and the time of the pulse probe ultrasound are shown in table 3. After the pulse probe finishes the ultrasonic treatment, the mixed solution is concentrated by a vacuum rotary evaporation method, and the specific temperature and the vacuum degree of the vacuum rotary evaporation method (referred to as rotary evaporation for short) are shown in table 3. The concentration of the solid content of the concentrated mixture (here, the solid content can be measured by high-speed centrifugation, drying, etc.) is shown in table 3. And concentrating to obtain the palladium nanosheet/graphene oxide dispersion liquid.
TABLE 3 parameters of the procedure for preparing the palladium nanosheet/graphene oxide dispersion
Spinning: carbon black and PAN powder are added to the prepared palladium nanosheet/graphene oxide dispersion, specifically, the mass-to-volume ratio of the carbon black to the palladium nanosheet/graphene oxide dispersion (the ratio of the mass of the carbon black to the volume of the palladium nanosheet/graphene oxide dispersion, referred to as "carbon black concentration"), and the mass fraction of PAN after PAN powder addition (mass fraction of PAN in the whole system) are shown in table 4. Stirring the palladium nanosheet/graphene oxide dispersion liquid until the carbon black and the PAN powder are uniformly dispersed, and then performing three-stage water bath ultrasound (referred to as "three-stage ultrasound"), wherein specific stirring speed, stirring time, temperature of the three-stage water bath ultrasound, power of the three-stage water bath ultrasound and time of the three-stage water bath ultrasound are shown in table 4. After the ultrasound is finished, the spinning solution is directly used for electrostatic spinning, a spinning needle with the inner diameter increased along the yarn outlet direction is used, the inner diameter of the thin end of the spinning needle is 0.3mm, the inner diameter of the thick end of the spinning needle is 0.36mm, the receiving distance is 20cm, and the voltage of the specific electrostatic spinning is shown in table 4.
TABLE 4 parameters of the spinning step
And (3) post-treatment: and (3) washing the palladium nanosheet/graphene oxide hybrid porous fiber membrane by using deionized water, drying in vacuum, and repeating the washing and drying processes once. Soaking the washed palladium nanosheet/graphene oxide hybrid porous fiber membrane in a reducing agent for reduction, wherein the specific type of the reducing agent can be HI or NaBH4Any of hydrazine hydrate and ascorbic acid, the kind of reducing agent in specific examples, reduction time are shown in table 5. Repeating the washing and drying processes for 1-2 times after reduction to obtain the palladium nanosheet/graphene-based fiberAnd (5) maintaining the membranes.
TABLE 5 parameters of the post-treatment step
Comparative example 1
Comparative example 1 the setup was made with reference to example 4, comparative example 1 differing from example 4 only in that: the steps of preparing the palladium nanosheet, and carrying out secondary water bath ultrasound, pulse probe ultrasound, spinning and post-treatment on the palladium nanosheet and the graphene oxide together are omitted.
A preparation method of a graphene-based fiber membrane comprises the following steps:
preparing a mixture of graphene oxide: adding graphene oxide to the isopropanol pre-stripping dispersion liquid, wherein the ratio of the mass of the graphene oxide to the volume of the isopropanol is 100 mg/ml. After the addition of graphene oxide, the pre-exfoliated dispersion of graphene oxide was transferred to a water bath kettle for secondary water bath ultrasound, wherein the temperature (secondary water bath ultrasound is simply referred to as "secondary ultrasound", and the temperature here is also a temperature value set for the water bath kettle), power, and ultrasound time of the secondary water bath ultrasound were the same as those of example 4. And after the secondary water bath ultrasound is finished, centrifuging the pre-stripping dispersion liquid added with the graphene oxide, and collecting a bottom layer mixture, wherein the centrifugal speed and the centrifugal time are the same as those in the embodiment 4. And dispersing the bottom layer mixture in water, oscillating and washing the bottom layer mixture, transferring the washed mixture into a vacuum rotary evaporator for rotary evaporation to remove the pre-stripping dispersion, transferring the rotary evaporated mixture into a vacuum drying oven for drying, wherein the temperature and the drying time of the drying oven are the same as those of the example 4.
Preparing a graphene oxide dispersion liquid: similarly to example 4, the mixture of graphene oxide prepared above was dispersed in DMF to prepare a mixed solution, and then subjected to pulse probe ultrasound and concentration in this order to prepare a graphene oxide dispersion.
Spinning: in the same manner as in example 4, carbon black and PAN powder were added to the graphene oxide dispersion liquid prepared above, specifically, the mass-to-volume ratio of carbon black to graphene oxide dispersion liquid was 80mg/ml, and the mass fraction of PAN was 9%, and the processes of stirring, three-stage water bath ultrasound, spinning, and the like were sequentially performed to prepare a graphene-based fiber membrane.
And (3) post-treatment: refer to example 4.
Comparative example 2
A preparation method of a palladium nanosheet/graphene-based fiber membrane comprises the following steps:
preparing a pre-stripping dispersion of palladium powder: refer to example 4.
Preparing a mixture of palladium powder and graphene oxide: to the previously prepared pre-exfoliated dispersion of palladium powder, graphene oxide was added, wherein the ratio of the mass of graphene oxide to the mass of palladium powder in the supernatant was with reference to example 4. The pre-exfoliated dispersion of palladium powder with added graphene oxide was centrifuged, and the bottom layer mixture was collected, where the centrifugation speed, the centrifugation time, and the like were as in example 4. The bottom layer mixture was dispersed in water, the bottom layer mixture was washed by shaking, the washed mixture was transferred to a vacuum rotary evaporator to remove the pre-peeling dispersion by rotary evaporation, and the rotary evaporated mixture was transferred to a vacuum drying oven to be dried, the temperature and drying time of the oven were as in example 4.
Preparing a palladium nanosheet/graphene oxide dispersion liquid: refer to example 4.
Spinning: refer to example 4.
And (3) post-treatment: refer to example 4.
Comparative example 3
A preparation method of a palladium nanosheet/graphene-based fiber membrane comprises the following steps:
preparing a pre-stripping dispersion of palladium powder: refer to example 4.
Preparing a mixture of palladium powder and graphene oxide: refer to example 4.
Preparing a palladium nanosheet/graphene oxide dispersion liquid: a mixture of palladium powder and graphene oxide was dispersed in DMF to prepare a mixed solution, wherein the concentration of the mixture of palladium powder and graphene oxide was as in example 4. The mixed solution was concentrated by a vacuum rotary evaporation method, and specifically, the temperature, the degree of vacuum, and the like of the vacuum rotary evaporation method (simply referred to as "rotary evaporation") were as in example 4. The solid content concentration of the concentrated mixture was as in example 4. And concentrating to obtain the palladium nanosheet/graphene oxide dispersion liquid.
Spinning: refer to example 4.
And (3) post-treatment: refer to example 4.
Effects of the embodiment
(1) Antibacterial testing
Taking the palladium nanosheet/graphene-based fiber membrane or the graphene-based fiber membrane prepared in the examples 1 to 8 and the comparative examples 1 to 3, cutting the fiber membrane with the length, the width and the thickness of 20cm and about 0.5mm by a blade, and inserting electrodes at two ends of the fiber membrane for electrifying and generating heat and carrying out an antibacterial test. The test method is as follows: the culture solution (rejuvenated) of model strains (escherichia coli, candida albicans, salmonella typhimurium, staphylococcus aureus) was spotted by means of an inoculating needle onto petri dishes (containing conventional solid medium for bacterial culture), each petri dish was inoculated with a single strain 10 times and each strain 200 times (divided into 20 dishes). After inoculation, all the culture dishes are divided into two groups and respectively placed in two culture chambers for simulating living environment. One of them is the laboratory group culture room, is provided with a plurality of aforementioned fibrous membranes in the laboratory group culture room and circular telegram heat production, and the culture dish is 5 ~ 30cm apart from the fibrous membrane, and the laboratory group culture room is by fibrous membrane heat production energy supply, and the temperature control in the culture room is about 37 ℃, and another culture room is the control group culture room, and the temperature that sets up the control group culture room equally is 37 ℃, is supplied heat by the air conditioner, and statistics laboratory group bacterial colony growth condition after 12h all cultivateed in laboratory group culture room and control group culture room. The average colony size (diameter of colony) of each bacterial colony in the control group is calculated, the average colony size is used as a reference value, the colony with the diameter less than or equal to half of the reference value in the experimental group is marked as bacteriostasis, the colony which does not grow at the point of sample application is marked as sterilization, and the colony with the diameter more than or equal to half of the reference value is marked as normal growth. The results of the statistical percentages are shown in Table 6.
TABLE 6 antimicrobial test results
From the results in table 6, it is clear that the palladium nanosheet/graphene-based fiber membranes prepared in examples 1-8 all showed over 99% of bactericidal rate against escherichia coli, candida albicans, and salmonella typhimurium, and over 91% of bactericidal rate against staphylococcus aureus after being electrified. After the palladium nanosheets and the graphene are mutually doped, the palladium nanosheets and the graphene can be promoted to be directly contacted and doped, the palladium nanosheets or the graphene are prevented from being stacked or partially gathered, the spinnability of a single two-dimensional material spinning solution can be improved, the palladium nanosheets and the graphene are mixed with dispersed carbon black powder, the mutually doped palladium nanosheets and the graphene are directly adsorbed on the carbon black powder, a stable conductive network structure of palladium nanosheets-graphene-carbon black particles can be formed, meanwhile, the palladium nanosheets or graphene layers are prevented from being stacked mutually or easily faulted (partially broken circuit) under the action of external force, the number of conductive network channels is increased, the resistance is reduced, the structure of a conductive network is perfected, and the conductive performance and the long-term stability of the palladium nanosheet/graphene-based fiber membrane are improved. After the palladium nanosheet/graphene-based fiber membrane is electrified, the surface area can be increased by virtue of a large number of void structures existing on the surface of the fiber membrane, the palladium nanosheet-graphene-carbon black particles are facilitated to release a large number of infrared rays, and the sterilization effect is achieved. In addition, by means of carrier transmission between the palladium nanosheet and the graphene sheet layer, a small amount of active oxygen free radicals can be generated at the heterojunction between the palladium nanosheet and the graphene sheet layer, and the effects of assisting sterilization and cleaning the surface are achieved.
In contrast, the graphene-based fiber membrane prepared in comparative example 1 has a sterilization rate of 80% for escherichia coli, candida albicans, and salmonella typhimurium and a sterilization rate of 67% for staphylococcus aureus after being electrified. The reason may be related to that the graphene-based fiber film prepared in comparative example 1 has a relatively low infrared emissivity, and the graphene-based fiber film prepared in comparative example 1 only contains electric conductors such as graphene and carbon black, and lacks the auxiliary effect of palladium nanosheets, so that the graphene-based fiber film has a relatively low infrared emissivity and cannot generate active radicals. The palladium nanosheet/graphene-based fiber membrane prepared in the comparative example 2 has the sterilization rate of 93% for escherichia coli, candida albicans and salmonella typhimurium and only 83% for staphylococcus aureus after being electrified. Based on the fact that sufficient water bath ultrasound is not performed in comparative example 2, graphene oxide is directly added into the pre-stripping dispersion liquid of palladium powder, the palladium nanosheet can not be stripped with the assistance of graphene, and an effective palladium nanosheet/graphene mutual doping structure can not be formed, so that the prepared palladium nanosheet/graphene-based fiber membrane active conductor has the defects of nonuniform dispersion, low infrared emissivity, low yield of active free radicals, low antibacterial efficiency and the like. The palladium nanosheet/graphene-based fiber membrane prepared in the comparative example 3 has the sterilization rate of 92% on escherichia coli, candida albicans and salmonella typhimurium and the sterilization rate of 79% on staphylococcus aureus after being electrified. As with comparative example 2, based on that pulse probe ultrasound is not performed in comparative example 3, the palladium nanosheet cannot be peeled off with the aid of graphene, and an effective palladium nanosheet/graphene mutual doping structure cannot be formed, resulting in the defects of uneven dispersion, low infrared emissivity, low yield of active free radicals, low antibacterial efficiency and the like of the prepared palladium nanosheet/graphene-based fiber membrane active conductor.
(2) Infrared wavelength and normal emissivity testing
The palladium nanosheet/graphene-based fiber membrane or the graphene-based fiber membrane prepared in the examples 1 to 8 and the comparative examples 1 to 3 is used for testing the infrared wavelength and the normal emissivity according to the health care function textile of CAS 115-. The calculation data show that the palladium nanosheet/graphene-based fiber membrane prepared in the embodiment 1-8 can release far infrared rays of 3-20 micrometers, the proportion of the far infrared rays in a 4-16 micrometer waveband is over 88%, the normal emissivity is over 90%, and the increase of the microcirculation blood flow of animal experiments is over 69%. The electrothermal conversion rate is up to more than 99%, and the visible heating film can be widely applied to the fields of floor heating, physical therapy, clothes and the like. In contrast, the ratio of far infrared rays in the 4-16 micron wavelength band of the palladium nanosheet/graphene-based fibrous membrane or the graphene-based fibrous membrane prepared in comparative examples 1-3 is less than 75% (67% for the graphene-based fibrous membrane in example 1), the normal emissivity is less than 81% (67% for the graphene-based fibrous membrane in example 1), and the increase in the animal experimental microcirculation blood flow is less than 64% (50% for the graphene-based fibrous membrane in example 1). The reason for this is probably related to the stable circuit network structure formed by the palladium nanosheet/graphene-based fiber membrane, i.e., the palladium nanosheet and the graphene are doped with each other, so that the uniform distribution of the electric conductor is increased, the resistance value of the fiber membrane is reduced, the uniformity of the spinning fiber is improved, and the like.
(3) Stability and leakage safety testing
Taking the palladium nanosheet/graphene-based fiber film or the graphene-based fiber film prepared in the examples 1 to 8 and the comparative examples 1 to 3, cutting the fiber film with the length, the width and the thickness of 20cm and about 0.5mm by a blade, inserting electrodes at two ends of the fiber film, connecting a mains supply to the palladium nanosheet/graphene-based fiber film or the graphene-based fiber film to generate heat, and assessing the uniformity of heating temperature by an infrared imaging instrument. The heating temperature difference of any two positions of each fiber membrane is less than or equal to 5 ℃ and more than 2.5 ℃, the fiber membrane is marked as qualified, the fiber membrane is less than or equal to 2.5 ℃, the fiber membrane is marked as excellent, the fiber membrane is marked as unqualified when the temperature is more than 5 ℃, and the statistical result is shown in table 7.
And continuously electrifying the palladium nanosheet/graphene-based fiber membrane or the graphene-based fiber membrane for heat generation uniformity test to generate heat for heat generation stability test. The statistical method, the heat production is carried out for 90000 hours by continuous electrification, and compared with the beginning of the heat production, the disqualification is marked when the heat production power is reduced by more than 2.5 percent after the 90000 hours of the heat production; the heat production power is reduced by less than or equal to 2.5 percent and is greater than 1 percent, and the product is marked as qualified; the decrease of heat generation power less than or equal to 1% is marked as excellent, and the statistical results are shown in Table 7.
The two surfaces of the composite palladium nanosheet/graphene-based fiber membrane or the graphene-based fiber membrane are hot-pressed by adopting an insulating polymer membrane (such as PET or PI), and the power is continuously electrified to generate heat for 90000 hours after the power is electrified so as to be used for a leakage safety test. The specific test method was measured with reference to GB/T12113 (idt IEC 60990). The leakage current is less than or equal to 0.05mA and greater than 0.02mA and is marked as qualified; the leakage current is less than 0.02mA and is marked as excellent; the leakage current is greater than 0.05mA and is marked as unqualified. The measurement results are shown in Table 7.
TABLE 7 stability and leakage safety test results
As can be seen from the results in table 7, most of the palladium nanosheet/graphene-based fibrous membranes prepared in examples 1 to 8 showed excellent test results in the temperature uniformity test, the heat generation stability test and the leakage safety test, and only example 1 showed a qualified test result, which indicates that the palladium nanosheet/graphene-based fibrous membranes prepared in examples 1 to 8 of the present invention have excellent heat generation uniformity, heat generation stability and leakage safety. The fiber films prepared in the comparative example 1 are unqualified in temperature uniformity test and heat generation stability test, and the fiber films prepared in the comparative examples 2 and 3 are qualified in temperature uniformity test and heat generation stability, and may be related to uneven dispersion of the conductor, unstable conductor and easy aging under the condition of electrifying.
(4) Sheet resistance test
Taking the palladium nanosheet/graphene-based fiber membrane or the graphene-based fiber membrane prepared in the examples 1 to 8 and the comparative examples 1 to 3, cutting the fiber membrane with the length, the width and the thickness of 20cm and about 0.5mm by a blade, inserting electrodes at two ends of the fiber membrane, connecting a mains supply to the palladium nanosheet/graphene-based fiber membrane or the graphene-based fiber membrane for heat generation, and carrying out a sheet resistance test. The test method is as follows: continuously electrifying the palladium nanosheet/graphene-based fiber membrane or the graphene-based fiber membrane to generate heat, and testing the sheet resistance value of the graphene fiber membrane once every other week (W). The test results are shown in Table 8.
TABLE 8 sheet resistance test results
As can be seen from the results in table 8, the sheet resistance of the palladium nanosheet/graphene-based fiber membranes prepared in examples 1 to 8 is small (no more than 350 Ω/□), the variation of the sheet resistance is not obvious around when heat is generated by continuous energization, and both the sheet resistance and the stability thereof are suitable for being applied to electric heating equipment and can be widely applied to the fields of floor heating, physiotherapy, clothing and the like. In contrast, the palladium nanosheet/graphene-based fibrous membrane or graphene-based fibrous membrane prepared in comparative examples 1-3 has a large initial sheet resistance (the sheet resistance value after stabilization is still large and may be related to instability and easy aging of the fibrous membrane component under the condition of electrification and heat generation), a large change in sheet resistance value, a significant decrease in heat generation power, and is not suitable for being applied to electric heating equipment. The reason for this is that the dispersion of the electrical conductor such as palladium nanosheets and graphene may be uneven.
(5) Heat resistance and tensile Property test
Taking the palladium nanosheet/graphene-based fiber membrane or the graphene-based fiber membrane prepared in the examples 1-8 and the comparative examples 1-3, cutting the fiber membrane with the blade, wherein the fiber membrane is 20cm long and wide and about 0.5mm thick, and carrying out a thermal deformation temperature test according to GB/T1634-2004, wherein the heating rate is 120 ℃/h. The test results are shown in Table 9.
The prepared palladium nanosheet/graphene-based fiber membrane or graphene-based fiber membrane is taken to be subjected to tensile resistance test on a universal tester (the test standard is GB/T1040-.
TABLE 9 Heat resistance test results
From the results in table 9, it can be seen that the thermal deformation temperatures of the palladium nanosheet/graphene-based fibrous membrane or the graphene-based fibrous membrane prepared in examples 1 to 8 and comparative examples 1 to 3 both exceed 98 ℃, and the fibrous membrane can meet the heat generation requirements of low-temperature and medium-high-temperature heat-generating equipment. The heat distortion temperature is related to the PAN content in the palladium nanosheet/graphene-based fibrous membrane or the graphene-based fibrous membrane. Within a certain range, the thermal deformation temperature of the palladium nanosheet/graphene-based fiber membrane or the graphene-based fiber membrane is increased along with the increase of the PAN content, and the good dispersion of the palladium nanosheet and the graphene is also beneficial to the increase of the thermal deformation temperature; however, too high a PAN content results in a dope that is too viscous and affects spinnability and fiber porosity.
From the results in table 9, it is known that the tensile strength of the palladium nanosheet/graphene-based fiber film or the graphene-based fiber film prepared in examples 1 to 8 and comparative examples 1 to 3 exceeds 20MPa, and the requirements of flexibility, wear resistance and tensile resistance of common heat-generating equipment can be met. The tensile strength of the fiber membrane is related to the content of PAN (polyacrylonitrile), within a certain range, the tensile strength of the palladium nanosheet/graphene-based fiber membrane or the graphene-based fiber membrane is improved along with the improvement of the content of PAN, and the good dispersion of the palladium nanosheet and graphene is also beneficial to improving the tensile strength.
(6) Test of photothermal conversion Property
The palladium nanosheet/graphene-based fiber film or the graphene-based fiber film prepared in example 4 and comparative examples 1 to 3 is cut into fiber films with the length, the width and the thickness of each fiber film being 20cm and about 0.5mm by a blade, the four fiber films are placed in an illumination box (the ambient temperature is 20 ℃) provided with a 35W HD xenon lamp (simulated sunlight), the distance between the four fiber films and the HD xenon lamp is 20cm, and the temperature change of the fiber films along with the extension of illumination time is tested by a temperature sensor. The test results are shown in FIG. 1.
As can be seen from the results in fig. 1, the palladium nanosheet/graphene-based fiber membrane prepared in example 4 was rapidly heated to 67 ℃ after being irradiated with light for one minute, and was heated to about 83 ℃ by continuous irradiation with light. The graphene-based fiber membrane prepared in comparative example 1 can be heated to 47 ℃ after being irradiated by light for one minute, and can be heated to about 66 ℃ by continuous irradiation. The palladium nanosheet/graphene-based fiber membrane prepared in comparative example 2 can be heated to 61 ℃ after being irradiated for one minute, and can be heated to about 78 ℃ by continuous irradiation. The palladium nanosheet/graphene-based fiber membrane prepared in comparative example 3 can be heated to 54 ℃ after being irradiated for one minute, and can be heated to about 75 ℃ by continuous irradiation. Therefore, the palladium nanosheet/graphene-based fiber membrane has the advantages of remarkable photothermal effect and high photo-thermal efficiency, can generate heat by utilizing solar energy when being applied to the fields of floor heating, physiotherapy and clothes, integrates the heat generation of electricity and the heat generation of heat of light, is convenient for users to use, and is energy-saving and environment-friendly.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A preparation method of a palladium nanosheet/graphene-based fiber membrane is characterized by comprising the following steps:
preparing a pre-stripping dispersion of palladium powder: providing palladium powder and adding the palladium powder into the pre-stripping dispersion liquid, performing primary water bath ultrasound on the pre-stripping dispersion liquid added with the palladium powder, wherein the temperature of the primary water bath ultrasound is 5-15 ℃, and centrifuging and collecting supernatant after the primary water bath ultrasound is finished to prepare the pre-stripping dispersion liquid of the palladium powder;
preparing a mixture of palladium powder and graphene oxide: adding graphene oxide into a pre-stripping dispersion liquid of palladium powder, performing secondary water bath ultrasound at the temperature of 5-15 ℃, centrifuging after the secondary water bath ultrasound is finished, collecting a bottom layer mixture, dispersing the bottom layer mixture in water, washing and drying to obtain a mixture of the palladium powder and the graphene oxide;
preparing a palladium nanosheet/graphene oxide dispersion liquid: dispersing a mixture of palladium powder and graphene oxide in DMF to prepare a mixed solution, performing ultrasonic treatment on the mixed solution by using a pulse probe at the ultrasonic temperature of 5-15 ℃, and concentrating the mixed solution after the ultrasonic treatment is finished to prepare a palladium nanosheet/graphene oxide dispersion solution;
spinning: adding carbon black and PAN powder into a palladium nanosheet/graphene oxide dispersion liquid, uniformly stirring, and then carrying out three-stage water bath ultrasound, wherein the temperature of the three-stage water bath ultrasound is 5-15 ℃, and after the three-stage water bath ultrasound is finished, the three-stage water bath ultrasound is used as a spinning stock solution, and electrostatic spinning and collection are carried out by using a spinning needle with the inner diameter increased along a filament outlet direction, so as to prepare the palladium nanosheet/graphene oxide hybrid porous fibrous membrane;
and (3) post-treatment: washing the palladium nanosheet/graphene oxide hybrid porous fiber membrane, drying and reducing to obtain a palladium nanosheet/graphene-based fiber membrane;
the mass of the graphene oxide is 0.5-5 times of the mass of the palladium powder in the pre-stripping dispersion liquid of the palladium powder, the mass fraction of PAN in the spinning stock solution is 8-12%, and the pre-stripping dispersion liquid is isopropanol, deionized water or a mixed solution of the isopropanol and the deionized water.
2. The preparation method of the palladium nanosheet/graphene-based fibrous membrane according to claim 1, wherein in the step of preparing the pre-exfoliated dispersion liquid of palladium powder, the mass-to-volume ratio of the palladium powder to the pre-exfoliated dispersion liquid is 10-500 mg/ml, the power of the primary water bath ultrasound is 250-500W, and the time of the primary water bath ultrasound is 24-72 hours;
the rotating speed of the centrifugation is 1500-3500 RPM, and the time of the centrifugation is 5-30 min.
3. The preparation method of the palladium nanosheet/graphene-based fibrous membrane according to claim 1, wherein in the step of preparing the mixture of palladium powder and graphene oxide, the power of the secondary water bath ultrasound is 250-500W, and the time of the secondary water bath ultrasound is 8-24 h;
the rotating speed of the centrifugation is 8000-15000 RPM, and the time of the centrifugation is 20-100 min.
4. The preparation method of the palladium nanosheet/graphene-based fibrous membrane according to claim 1, wherein in the step of preparing the mixture of palladium powder and graphene oxide, the mixture at the bottom layer is dispersed in water and washed, then the solvent is concentrated and removed by using a rotary evaporation method, and the concentrated mixture is transferred to a temperature of 30-40 ℃ for vacuum drying for 2-8 hours to prepare the mixture of palladium powder and graphene oxide.
5. The preparation method of the palladium nanosheet/graphene-based fibrous membrane according to claim 1, wherein in the step of preparing the palladium nanosheet/graphene oxide dispersion, the mass-to-volume ratio of the mixture of the palladium powder and the graphene oxide to the DMF is 1-10 mg/ml, the time of the pulsed probe ultrasound is 2-12 h, the power of the pulsed probe ultrasound is 200-300W, and the frequency of the pulsed probe ultrasound is set as follows: ultrasound 5s, interval 5 s.
6. The preparation method of the palladium nanosheet/graphene-based fibrous membrane according to claim 1, wherein in the step of preparing the palladium nanosheet/graphene oxide dispersion liquid, the mixed liquid is concentrated by a vacuum rotary evaporation method after the ultrasonic treatment is finished, and the concentration is carried out until the solid content concentration is 10-50 mg/ml;
the vacuum degree of the vacuum rotary evaporation method is 0.05-0.08 MPa, and the temperature of the vacuum rotary evaporation method is 55-65 ℃.
7. The method for producing a palladium nanosheet/graphene-based fibrous membrane according to claim 1, wherein in the spinning step, the mass to volume ratio of the carbon black to the palladium nanosheet/graphene oxide dispersion is 50 to 100 mg/ml;
the time of the three-stage water bath ultrasound is 4-12 hours, the power of the three-stage water bath ultrasound is 250-500W, and the collection is realized by collecting palladium nanosheets/graphene oxide hybrid porous fibers by adopting a collecting plate.
8. The preparation method of a palladium nanosheet/graphene-based fibrous membrane according to claim 1, wherein in the spinning step, the inner diameter of the thin end of the spinning needle is 0.3mm, the inner diameter of the thick end of the spinning needle is 0.36mm, the electrostatic spinning voltage is 20-50 KV, and the receiving distance is 10-30 cm.
9. The preparation method of the palladium nanosheet/graphene-based fibrous membrane according to claim 1, wherein in the post-treatment step, the palladium nanosheet/graphene oxide hybrid porous fibrous membrane is washed with deionized water for 1-3 times, and the palladium nanosheet/graphene oxide hybrid porous fibrous membrane is transferred to a vacuum drying oven at 60-85 ℃ for drying for 4-12 hours;
soaking the dried palladium nanosheet/graphene oxide hybrid porous fiber membrane in HI、NaBH4And hydrazine hydrate and ascorbic acid, and preparing the palladium nanosheet/graphene-based fiber membrane.
10. A palladium nanoplate/graphene-based fiber membrane produced by the method for producing a palladium nanoplate/graphene-based fiber membrane according to any one of claims 1 to 9.
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