CN112020160A

CN112020160A - Non-layered molybdenum nanosheet/graphene-based heating film

Info

Publication number: CN112020160A
Application number: CN202010937482.9A
Authority: CN
Inventors: 吴立刚; 叶德林; 张以河; 马宇飞; 李明; 李正博
Original assignee: Beijing Kangene Technology Innovation Research Co ltd
Current assignee: Beijing Kangene Technology Innovation Research Co ltd
Priority date: 2020-09-08
Filing date: 2020-09-08
Publication date: 2020-12-01

Abstract

The invention provides a non-layered molybdenum nanosheet/graphene-based heating film which comprises a first transparent insulating layer, an electrode, a second transparent insulating layer and a non-layered molybdenum nanosheet/graphene-based fibrous membrane, wherein the first transparent insulating layer covers one surface of the non-layered molybdenum nanosheet/graphene-based fibrous membrane, the second transparent insulating layer covers the other surface of the non-layered molybdenum nanosheet/graphene-based fibrous membrane, one end of the electrode is electrically connected with the non-layered molybdenum nanosheet/graphene-based fibrous membrane, and the other end of the electrode extends out of the first transparent insulating layer or the second transparent insulating layer. The non-layered molybdenum nano sheet/graphene-based heating film realizes the electric heating and photo-thermal diversified heat production functions by means of the high-efficiency photo-thermal conversion efficiency and the electric heating conversion efficiency of the non-layered molybdenum nano sheet/graphene-based fiber film.

Description

Non-layered molybdenum nanosheet/graphene-based heating film

Technical Field

The invention relates to the technical field of graphene heating devices, in particular to a flexible non-layered molybdenum nanosheet/graphene-based heating film.

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 after being repeatedly folded and stretched, so that the graphene heating coating is broken, and the heat production effect and the service life of the graphene heating coating are influenced. 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. The development of a heating film with small resistance, strong heat resistance and excellent circuit conductivity based on the graphene fiber film becomes a great research and development hotspot.

Disclosure of Invention

In view of the above, the invention provides a flexible non-layered molybdenum nanosheet/graphene-based heating film, so as to solve the defects of large resistance, poor heat resistance, poor circuit conductivity, poor waterproof performance and the like of the existing heating film.

In a first aspect, the invention provides a non-layered molybdenum nanosheet/graphene-based heating film, which comprises a first transparent insulating layer, an electrode, a second transparent insulating layer and a non-layered molybdenum nanosheet/graphene-based fibrous membrane, wherein the first transparent insulating layer covers one surface of the non-layered molybdenum nanosheet/graphene-based fibrous membrane, the second transparent insulating layer covers the other surface of the non-layered molybdenum nanosheet/graphene-based fibrous membrane, one end of the electrode is electrically connected with the non-layered molybdenum nanosheet/graphene-based fibrous membrane, and the other end of the electrode extends out of the first transparent insulating layer or the second transparent insulating layer;

the preparation method of the non-layered molybdenum nanosheet/graphene-based fiber membrane comprises the following steps:

preparing a pre-stripping dispersion of molybdenum powder: providing molybdenum powder and adding the molybdenum powder into the pre-stripping dispersion liquid, performing primary water bath ultrasound on the pre-stripping dispersion liquid added with the molybdenum powder, wherein the temperature of the primary water bath ultrasound is 5-15 ℃, and centrifuging and collecting supernatant after the ultrasound is finished to prepare the pre-stripping dispersion liquid of the molybdenum powder;

preparing a mixture of molybdenum powder and graphene oxide: adding graphene oxide into a pre-stripping dispersion liquid of molybdenum powder, performing secondary water bath ultrasound, wherein the temperature of the secondary water bath ultrasound is 5-15 ℃, centrifuging after the ultrasound is finished, collecting a bottom layer mixture, dispersing the bottom layer mixture in water, washing and drying to obtain a mixture of the molybdenum powder and the graphene oxide;

preparing a non-layered molybdenum nanosheet/graphene oxide dispersion liquid: dispersing a mixture of molybdenum powder and graphene oxide in N-methyl pyrrolidone to prepare a mixed solution, performing ultrasonic treatment on the mixed solution by using a pulse probe, wherein the ultrasonic temperature of the pulse probe is 5-15 ℃, and concentrating the mixed solution after the ultrasonic treatment is finished to prepare a non-layered molybdenum nanosheet/graphene oxide dispersion solution;

spinning: adding carbon black into a non-layered molybdenum nanosheet/graphene oxide dispersion liquid, uniformly stirring, performing three-stage water bath ultrasound, wherein the temperature of the three-stage water bath ultrasound is 5-15 ℃, adding PI powder into a mixed system after the ultrasound is finished, transferring the mixed system into an oil bath kettle at 103-110 ℃, uniformly stirring, uniformly mixing to obtain a spinning solution, performing electrostatic spinning by using a spinning needle with the inner diameter increased along the filament outlet direction, and collecting to obtain a non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane;

and (3) post-treatment: washing the non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane, drying and reducing to obtain a non-layered molybdenum nanosheet/graphene-based fiber membrane;

the mass of the graphene oxide is 0.5-5 times of that of molybdenum powder in a pre-stripping dispersion liquid of the molybdenum powder, the mass fraction of PI 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 non-layered molybdenum nanosheet/graphene-based heating film comprises a first transparent insulating layer, an electrode, a second transparent insulating layer and a non-layered molybdenum nanosheet/graphene-based fiber film, wherein the first transparent insulating layer and the second transparent insulating layer are attached to two surfaces of the non-layered molybdenum nanosheet/graphene-based fiber film, so that the non-layered molybdenum nanosheet/graphene-based fiber film is isolated in a closed insulating space, and electric leakage is prevented under the condition that the non-layered molybdenum nanosheet/graphene-based fiber film generates heat when being electrified. One end of the electrode is electrically connected with the non-layered molybdenum nanosheet/graphene-based fibrous membrane, and the other end of the electrode extends out of the first transparent insulating layer or the second transparent insulating layer, so that the non-layered molybdenum nanosheet/graphene-based fibrous membrane can be electrically conducted with an external power supply through the electrode. The first transparent insulating layer and the second transparent insulating layer can also ensure that the non-layered molybdenum nanosheet/graphene-based fiber membrane can receive light radiation, and by means of the high-efficiency photothermal conversion efficiency and the electric-heating conversion efficiency of the non-layered molybdenum nanosheet/graphene-based fiber membrane, the electric-heating and photothermal integrated diversified heat production function is realized.

The preparation method of the non-layered molybdenum nanosheet/graphene-based fibrous membrane comprises the steps of preparing a pre-stripping dispersion liquid of molybdenum powder, preparing a mixture of the molybdenum powder and graphene oxide, preparing the non-layered molybdenum nanosheet/graphene oxide dispersion liquid, spinning and post-treating. The step of preparing the pre-stripping dispersion liquid of the molybdenum powder can strip the molybdenum powder in advance, and the stripping efficiency of the molybdenum powder and the preparation efficiency of the non-layered molybdenum nanosheets are improved by collecting the primarily stripped molybdenum powder and using the primarily stripped molybdenum powder for the next stripping. In the step of preparing the mixture of the molybdenum powder and the graphene oxide, the preliminarily peeled molybdenum powder and the graphene oxide are subjected to water bath ultrasound together, so that the molybdenum powder is poor in dispersibility in the pre-peeling dispersion liquid, the graphene is added into the pre-peeling dispersion liquid of the molybdenum powder and the water bath ultrasound is carried out together, and the molybdenum 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 non-layered molybdenum nanosheet/graphene oxide dispersion liquid, the mixed liquid is subjected to ultrasonic treatment by adopting a pulse probe, so that the non-layered molybdenum nanosheets can be effectively prepared, and the non-layered molybdenum nanosheets and the graphene oxide dispersion liquid are further mixed, so that the phenomenon that the non-layered molybdenum nanosheets are stacked mutually to cause overhigh local concentration and cannot be spun is prevented, and the conductivity and the dispersion uniformity among graphene layers can be improved. The first-stage water bath ultrasound, the second-stage water bath ultrasound and the pulse probe ultrasound are carried out at low temperature, so that the prepared non-layered molybdenum nanosheets can be effectively prevented from being degraded. In the spinning step, the non-layered molybdenum nanosheet/graphene oxide dispersion liquid and the carbon black are added into an N-methyl pyrrolidone solution, three-stage water bath ultrasound is performed after uniform stirring, the spinning stock solution is more uniform through the stirring and ultrasound processes, the uniformity of the physical size and the performance of the spun yarn is ensured, the carbon black can be fully dispersed in the non-layered molybdenum nanosheet/graphene oxide dispersion liquid, and the uniform distribution and the uniform conductivity of the electric conductors of the spun fiber are ensured. And further adding high molecular polymer PI powder, performing oil bath, stirring and uniformly mixing to ensure that the electric conductor is fully doped on the PI high molecular compound, and preparing the uniformly-conductive non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber. In the post-treatment step, the non-layered molybdenum 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 non-layered molybdenum nanosheet/graphene-based fiber membrane is prepared, and has the advantages of stable chemical property, heat resistance, strong electric conductivity, high infrared radiation rate, integrated heat and heat collection performance and the like.

According to the preparation method of the non-layered molybdenum nanosheet/graphene-based fibrous membrane, graphene oxide is added in the preparation process of the non-layered molybdenum nanosheets, so that the molybdenum powder can be assisted to be stripped into the non-layered molybdenum nanosheets, and the non-layered molybdenum nanosheets and the graphene oxide can be uniformly mixed. The non-layered molybdenum nanosheets, the graphene 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, high temperature resistance and the like due to the fact that a large amount of PI macromolecules are contained in the fiber.

Preferably, a transparent heat conduction layer is further arranged between the second transparent insulation layer and the non-layered molybdenum nanosheet/graphene-based fiber membrane. By arranging the transparent heat conduction layer, on one hand, light radiation cannot be influenced to penetrate through the transparent heat conduction layer and act on the non-laminated molybdenum nanosheet/graphene-based fiber membrane, and photo-thermal conversion is realized; on the other hand, the transparent heat conducting layer can also efficiently conduct out heat and infrared radiation generated after the non-layered molybdenum nanosheet/graphene-based fiber membrane is electrified.

Preferably, a waterproof bonding layer is further arranged between the first transparent insulating layer and the second transparent insulating layer, and the waterproof bonding layer is bonded with the first transparent insulating layer and the second transparent insulating layer respectively to form a closed cavity;

the non-layered molybdenum nanosheet/graphene-based fiber membrane and the transparent heat conduction layer are both arranged in the closed cavity, and the electrode extends out of the closed cavity. The first transparent insulating layer and the second transparent insulating layer are respectively bonded with the waterproof bonding layer to form a closed cavity, and the non-layered molybdenum nanosheet/graphene-based fiber membrane and the transparent heat conducting layer are both arranged in the closed cavity, so that a good insulating and waterproof effect is achieved.

Preferably, the electrode comprises a transverse arm and a vertical arm which are connected with each other, the transverse arm extends out of the transparent heat conduction layer to form the closed cavity, and the vertical arm extends out of the transparent heat conduction layer and is electrically connected with the non-layered molybdenum nano sheet/graphene-based fiber membrane. The electrodes are arranged in an L shape and comprise a transverse arm and a vertical arm which are mutually connected, the L-shaped electrodes can realize that the non-layered molybdenum nano sheet/graphene-based fiber membrane is electrically connected with an external power supply, the non-layered molybdenum nano sheet/graphene-based fiber membrane can not receive illumination from the first transparent insulating layer, and an L-shaped loop can also form a closed waterproof cavity, so that the non-layered molybdenum nano sheet/graphene-based heating membrane is favorable for water prevention.

Preferably, the heat reflection type solar cell further comprises a heat reflection layer which is arranged in a concave shape to form an accommodating groove;

the first transparent insulating layer and the non-layered molybdenum nanosheet/graphene-based fiber film are arranged in the accommodating groove. The first transparent insulating layer and the non-layered molybdenum nanosheet/graphene-based fiber film are arranged in the accommodating groove to form a waterproof loop structure, so that electric leakage of the non-layered molybdenum nanosheet/graphene-based fiber film is prevented. In addition, the heat reflecting layer arranged in the concave shape covers one bottom surface and the peripheral side walls of the non-layered molybdenum nanosheet/graphene-based fiber membrane, so that the non-layered molybdenum nanosheet/graphene-based fiber membrane can only radiate heat from the opening direction of the heat reflecting layer when being electrified to generate heat, and has the effects of restraining the infrared radiation direction, controlling the heat conduction direction and improving the heat utilization rate.

Preferably, one end of the transparent heat conduction layer, which faces the non-layered molybdenum nanosheet/graphene-based fiber membrane, is embedded into the accommodating groove, and one end of the transparent heat conduction layer, which faces the second transparent insulation layer, is connected with the second transparent insulation layer. The transparent heat conduction layer is embedded into the accommodating groove towards one end of the non-layered molybdenum nanosheet/graphene-based fiber membrane to form a waterproof loop structure, so that electric leakage of the non-layered molybdenum nanosheet/graphene-based fiber membrane is prevented.

Preferably, the heat reflecting layer includes a reflecting film and an insulating film, the reflecting film covering an outer surface of the insulating film;

the insulating film is equipped with the flange towards the one end of second transparent insulation layer, be equipped with the draw-in groove that is used for the holding flange on the periphery wall of waterproof adhesive linkage. Can effectively prevent non-laminar molybdenum nano sheet/graphite alkene base fiber membrane and reflectance coating direct contact and electric leakage through setting up reflectance coating and insulating film, set to the connection mode of dismantling between insulating film and the waterproof adhesive linkage, can dismantle the heat reflection stratum when needs are followed first transparent insulation layer light-conducting to the realization lasts light and heat conversion. When needing to be electrified to generate heat, the non-layered molybdenum nanosheet/graphene-based fiber membrane is electrified and covered with the heat reflecting layer, so that the heat can be effectively prevented from being diffused out of the first transparent insulating layer, and the heat-conducting heat-insulating heat-conducting heat.

Preferably, the reflective film is an aluminum foil film or a silver foil film, and the insulating film is a flexible resin film. By virtue of the flexibility of the flexible resin film and the toughness of the aluminum foil or silver foil, the covering of the heat reflecting layer can be easily achieved by deformation.

Preferably, in the step of preparing the pre-stripping dispersion liquid of the molybdenum powder, the mass-volume ratio of the molybdenum 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 effect of pre-stripping the molybdenum simple substance can be achieved through the primary water bath ultrasound, the subsequent centrifugal process can separate the pre-stripped few-layer molybdenum simple substance from the un-stripped molybdenum powder, the few-layer molybdenum simple substance generated by pre-stripping is transferred to the next stripping procedure, and the few-layer non-laminar molybdenum nanosheet is efficiently prepared.

Preferably, in the step of preparing the mixture of molybdenum 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 molybdenum powder which is preliminarily peeled off, further performing secondary water bath ultrasound, mixing the graphene oxide with the molybdenum powder which is preliminarily peeled off, wherein the graphene oxide has the effect of assisting the peeling and dispersion of the molybdenum powder, and preventing the non-layered molybdenum nanosheets from being stacked. And further collecting the non-layered molybdenum nanosheets and graphene oxide generated by stripping through centrifugation for subsequent steps.

Preferably, in the step of preparing the mixture of molybdenum 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 mixture is transferred to a temperature of 30-40 ℃ for vacuum drying for 2-8 hours after concentration, so as to prepare the mixture of the molybdenum powder and the graphene oxide. Residual pre-stripping dispersion liquid on a mixture of molybdenum powder and graphene oxide can be effectively removed through the steps of removing a solvent through rotary evaporation, vacuum drying and the like, the subsequent steps of preparing a non-layered molybdenum nanosheet/graphene oxide dispersion liquid and spinning are facilitated, the spinnability of a spinning stock solution is improved, and meanwhile, the concentration of the non-layered molybdenum nanosheet/graphene oxide dispersion liquid is conveniently measured.

Preferably, in the step of preparing the non-layered molybdenum nanosheet/graphene oxide dispersion liquid, the mass-to-volume ratio of the mixture of the molybdenum powder and the graphene oxide to the N-methylpyrrolidone 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 molybdenum powder and graphene oxide can be promoted to be well dispersed in N-methyl pyrrolidone by the aid of pulse probe ultrasound, and a dispersion liquid with well dispersed non-layered molybdenum nanosheets and graphene oxide is prepared to prepare a spinning stock solution for subsequent preparation.

Preferably, in the step of preparing the non-layered molybdenum 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 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 45-55 ℃. The non-layered molybdenum nanosheet/graphene oxide dispersion liquid is prepared through two steps, namely, the non-layered molybdenum nanosheet and graphene oxide are dispersed at low concentration and then concentrated to high concentration meeting the spinning requirement, so that the non-layered molybdenum nanosheet and graphene oxide can be well dispersed in N-methyl pyrrolidone, the conductive requirement of a fiber membrane can be met, the content of a conductor in the non-layered molybdenum 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 non-layered molybdenum nanosheet/graphene oxide dispersion is 20-50 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 to collect the non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber by adopting a collecting plate. The addition of the carbon black can further improve the conductivity of the non-layered molybdenum nanosheet/graphene-based fibrous membrane, regulate and control the ratio of the carbon black to the non-layered molybdenum nanosheet/graphene oxide dispersion liquid, improve the conductivity of the non-layered molybdenum nanosheet/graphene-based fibrous membrane, avoid the influence of excessive use of the carbon black on the spinnability of a spinning solution, and reduce the flexibility of the non-layered molybdenum nanosheet/graphene-based fibrous membrane. The non-layered molybdenum nanosheets, 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 doped into the non-layered molybdenum nanosheets/graphene hybrid porous fibers uniformly, and the non-layered molybdenum nanosheets/graphene-based fiber membrane with good flexibility, high conductivity, excellent heat resistance and strong mechanical properties 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 non-lamellar molybdenum nanosheets and graphene oxide are distributed along the radial direction, and the non-lamellar molybdenum nanosheets/graphene oxide hybrid porous fiber formed after curing has a large number of pore-shaped structures distributed along the radial direction, so that the non-lamellar molybdenum nanosheets/graphene oxide hybrid porous fiber has good radial flexibility and axial elasticity, and the non-lamellar molybdenum nanosheets/graphene oxide hybrid porous fiber membrane also has good flexibility and elasticity in all directions.

Preferably, in the post-treatment step, the non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane is washed by deionized water for 1-3 times, and the non-layered molybdenum 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 non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane in HI and NaBH₄And hydrazine hydrate and ascorbic acid are reduced to prepare the non-layered molybdenum nanosheet/graphene-based fiber membrane. And removing residual N-methyl pyrrolidone in the non-layered molybdenum nanosheets/graphene-based fiber membrane through washing and drying processes to prepare the PI/non-layered molybdenum nanosheets/graphene oxide hybrid porous fiber membrane, wherein the washed and dried PI/non-layered molybdenum nanosheets/graphene oxide hybrid porous fiber membrane has higher porosity and larger specific surface area and flexibility. Finally through a reduction processThe graphene oxide is reduced into reduced graphene oxide, and the reduced non-layered molybdenum nanosheet/graphene-based fiber membrane has better environmental stability and heat resistance, so that the service life of the non-layered molybdenum nanosheet/graphene-based fiber membrane is effectively prolonged.

The non-layered molybdenum 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 non-layered molybdenum nanosheet/graphene-based fiber membrane is applied to floor heating, physical therapy or clothes, the non-layered molybdenum nanosheet/graphene-based fiber membrane also has the effect of infrared physical therapy. The base fiber material of the non-layered molybdenum nanosheet/graphene-based fiber membrane is Polyimide (PI), so that the non-layered molybdenum nanosheet/graphene-based fiber membrane has the advantages of high mechanical property, high temperature resistance, difficulty in aging and the like. When the non-layered molybdenum nanosheet/graphene-based fiber film is applied to a heating device, the non-layered molybdenum nanosheet/graphene-based fiber film has the advantages of uniform heat generation, stable heating performance, high infrared emission performance, 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 schematic structural diagram of a non-layered molybdenum nanosheet/graphene-based heating film according to an embodiment of the present invention;

fig. 2 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.

As shown in fig. 1, a non-layered molybdenum nanoplate/graphene-based heating film according to an embodiment of the present invention is shown. The non-layered molybdenum nanosheet/graphene-based heating film comprises a first transparent insulating layer 1, an electrode 2, a second transparent insulating layer 3 and a non-layered molybdenum nanosheet/graphene-based fiber film 4. The first transparent insulating layer 1 covers the upper surface of the non-layered molybdenum nanosheet/graphene-based fiber membrane 4, and the second transparent insulating layer 3 covers the lower surface of the non-layered molybdenum nanosheet/graphene-based fiber membrane 4, so that the non-layered molybdenum nanosheet/graphene-based fiber membrane 4 is isolated in a closed insulating space, and electric leakage is prevented when the non-layered molybdenum nanosheet/graphene-based fiber membrane 4 is electrified and generates heat. One end of the electrode 2 is electrically connected with the non-layered molybdenum nanosheet/graphene-based fiber membrane 4, specifically, the electrode 2 penetrates through the non-layered molybdenum nanosheet/graphene-based fiber membrane 4, or the non-layered molybdenum nanosheet/graphene-based fiber membrane 4 presses the electrode 2. The other end of the electrode 2 extends out of the first transparent insulating layer 1 (or extends out of the second transparent insulating layer 3, and also has the function of electrically connecting the non-layered molybdenum nanosheet/graphene-based fiber membrane 4 and the function of waterproofing), that is, the electrode 2 extends to the outside from the inside of the insulating space between the first transparent insulating layer 1 and the second transparent insulating layer 3, so that the non-layered molybdenum nanosheet/graphene-based fiber membrane 4 is electrically conducted with an external power supply. The first transparent insulating layer 1 and the second transparent insulating layer 3 can also ensure that the non-layered molybdenum nanosheet/graphene-based fiber membrane 4 can receive optical radiation, and the electric heating and optical heating diversified heat production function is realized by means of the high-efficiency optical-thermal conversion efficiency of the non-layered molybdenum nanosheet/graphene-based fiber membrane.

Further, the material of the first transparent insulating layer 1 and the second transparent insulating layer 3 may be PET or PI.

Further, a transparent heat conduction layer 5 is arranged between the second transparent insulation layer 3 and the non-layered molybdenum nanosheet/graphene-based fiber membrane 4. The transparent heat conduction layer 5 can be transparent heat conduction glue or a flexible water bag (for example, water contained in a transparent film), and one allows light to pass through without affecting the photothermal conversion effect of the non-laminated molybdenum nanosheet/graphene-based fiber membrane 4; the transparent heat conducting layers 5 of the two layers have larger specific heat capacity generally and can play a certain heat storage role.

Further, a waterproof adhesive layer 6 is further arranged between the first transparent insulating layer 1 and the second transparent insulating layer 3, and the waterproof adhesive layer 6 is respectively adhered to the first transparent insulating layer 1 and the second transparent insulating layer 3 to form a closed cavity. The non-layered molybdenum nanosheet/graphene-based fibrous membrane 4 and the transparent heat conduction layer 5 are both arranged in the closed cavity, and the electrode 2 extends out of the closed cavity from the inside of the closed cavity.

Further, the electrode 2 comprises a transverse arm and a vertical arm which are mutually and vertically connected, the transverse arm transversely extends out of the closed cavity from the transparent heat conduction layer, and the vertical arm longitudinally extends out of the transparent heat conduction layer and is electrically connected with the non-layered molybdenum nano sheet/graphene-based fiber membrane 4. In other embodiments, the electrode 2 may have other structures, and only the non-layered molybdenum nanosheet/graphene-based fiber membrane 4 is ensured to be electrically conducted with the outside through the electrode 2.

Further, a heat reflecting layer 7 is included, and the heat reflecting layer 7 is formed in a concave shape to form a receiving groove 73. The first transparent insulating layer 1 and the non-layered molybdenum nanosheet/graphene-based fibrous membrane 4 are both disposed in the accommodating groove 73. The heat reflection layer 7 and the first transparent insulation layer 1, the waterproof adhesive layer 6 or the second transparent insulation layer 3 can be fixedly connected or detachably connected.

Further, the heat reflecting layer 7 includes a reflecting film 71 and an insulating film 72, and the reflecting film 71 covers an outer surface of the insulating film 72.

Further, a flange 74 is provided at an end of the insulating film 72 facing the second transparent insulating layer 3, and a groove 61 for receiving the flange 74 is provided on an outer peripheral wall of the waterproof adhesive layer 6. And is removably attached to the card slot 61 by a flange 74.

Further, the reflective film 71 is an aluminum foil film or a silver foil film, and the insulating film 72 is a flexible resin film. In other embodiments, the heat reflecting layer 7 may also be coated glass.

The following describes in detail the preparation method of the non-layered molybdenum nanosheet/graphene-based fibrous membrane and the prepared non-layered molybdenum nanosheet/graphene-based fibrous membrane through specific examples, including examples and comparative examples (hereinafter referred to as "comparative examples"), which are set with reference to the parameter ranges of example 4 for discussing the influence of various parameters on the performance of the non-layered molybdenum nanosheet/graphene-based fibrous membrane.

A preparation method of a non-layered molybdenum nanosheet/graphene-based fiber membrane comprises the following steps:

preparing a pre-stripping dispersion of molybdenum powder: molybdenum 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 molybdenum powder in the pre-peeling dispersion are shown in table 1. The pre-stripped dispersion added with molybdenum powder is subjected to primary water bath ultrasound, wherein the temperature (the primary water bath ultrasound is referred to as "one-super", the temperature is set by a water bath kettle, and the actual water bath temperature has 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 molybdenum powder, and collecting supernatant to prepare the pre-stripping dispersion liquid of the molybdenum powder, wherein the centrifugal rotating speed and the centrifugal time are shown in table 1.

TABLE 1 parameters of the Pre-stripping Dispersion step for preparing molybdenum powder

Preparing a mixture of molybdenum powder and graphene oxide: to the pre-exfoliated dispersion of molybdenum powder prepared as described above, graphene oxide was added, wherein the ratio of the mass of graphene oxide to the mass of molybdenum powder in the supernatant (where molybdenum powder in the supernatant refers to molybdenum powder dispersed in the supernatant, and the mass of molybdenum powder in the supernatant can be obtained by subtracting the mass of molybdenum powder centrifugally precipitated in the pre-exfoliation step from the mass of total molybdenum powder supplied) is shown in table 2. After the addition of graphene oxide, the pre-exfoliated dispersion liquid of graphene oxide and molybdenum 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 second-stage water bath ultrasound treatment is finished, centrifuging the pre-stripping dispersion liquid of the molybdenum 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 molybdenum powder and graphene oxide

Preparing a non-layered molybdenum nanosheet/graphene oxide dispersion liquid: the mixture of molybdenum powder and graphene oxide was dispersed in N-methylpyrrolidone to prepare a mixed solution, wherein the concentration of the mixture of molybdenum powder and graphene oxide (referred to as "mixture concentration") is shown in table 3. Performing ultrasonic treatment on an N-methylpyrrolidone solution of a mixture of molybdenum powder and graphene oxide by using pulse probe ultrasonic treatment, wherein the frequency of the pulse probe ultrasonic treatment 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 non-layered molybdenum nanosheet/graphene oxide dispersion liquid.

TABLE 3 parameters of the step of preparing a non-lamellar molybdenum nanoplate/graphene oxide dispersion

Spinning: carbon black was added to the non-layered molybdenum nanoplatelets/graphene oxide dispersion prepared as described above, and specifically, the ratio of the mass to the volume of the carbon black to the non-layered molybdenum nanoplatelets/graphene oxide dispersion (the ratio of the mass of the carbon black to the volume of the non-layered molybdenum nanoplatelets/graphene oxide dispersion, referred to as "carbon black concentration" for short) is shown in table 4. Stirring the non-layered molybdenum nanosheet/graphene oxide dispersion liquid until the carbon black is uniformly dispersed, and then carrying out three-stage water bath ultrasound (referred to as 'three-stage ultrasound'), wherein the specific temperature, power and time of the three-stage water bath ultrasound are shown in table 4. After the ultrasound treatment is finished, adding PI powder into the mixed system containing the carbon black, the non-layered molybdenum nanosheets and the graphene oxide, transferring the mixed system into an oil bath pan for oil bath, and continuously performing mechanical stirring in the oil bath process, wherein the mass fraction (mass fraction of PI in the whole system), the oil bath temperature, the stirring speed and the stirring time after the PI powder is added are shown in a table 4. After the oil bath is finished, the solution is cooled to room temperature and is directly used as spinning solution for electrostatic spinning, a spinning needle with the inner diameter increased along the filament 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 non-layered molybdenum 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 non-layered molybdenum 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 NaBH₄Hydrazine hydrate andany of ascorbic acid, reducing agent species in specific examples, reduction time are shown in table 5. And repeating the washing and drying processes for 1-2 times after reduction to obtain the non-layered molybdenum nanosheet/graphene-based fiber membrane.

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 non-layered molybdenum nanosheets, and carrying out secondary water bath ultrasound, pulse probe ultrasound, spinning and post-treatment on the non-layered molybdenum nanosheets 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 N-methylpyrrolidone to prepare a mixed solution, and then subjected to pulse probe ultrasound and concentration in this order to prepare a graphene oxide dispersion liquid.

Spinning: in the same manner as in example 4, carbon black was added to the graphene oxide dispersion prepared above, specifically, the mass-to-volume ratio of carbon black to graphene oxide dispersion was 40mg/ml, and the processes of stirring, three-stage water bath ultrasound, addition of PI powder, oil bath, stirring, 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

preparing a pre-stripping dispersion of molybdenum powder: refer to example 4.

Preparing a mixture of molybdenum powder and graphene oxide: graphene oxide was added to the previously prepared pre-exfoliated dispersion of molybdenum powder, wherein the ratio of the mass of graphene oxide to the mass of molybdenum powder in the supernatant was referred to example 4. The pre-exfoliated dispersion of molybdenum powder with graphene oxide added was centrifuged, and the bottom layer mixture was collected, wherein 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 non-layered molybdenum 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

preparing a pre-stripping dispersion of molybdenum powder: refer to example 4.

Preparing a mixture of molybdenum powder and graphene oxide: refer to example 4.

Preparing a non-layered molybdenum nanosheet/graphene oxide dispersion liquid: a mixture of molybdenum powder and graphene oxide was dispersed in N-methylpyrrolidone to prepare a mixed solution, wherein the concentration of the mixture of molybdenum 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 non-layered molybdenum 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 non-layered molybdenum nanosheet/graphene-based fiber film or 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, and inserting electrodes at two ends of the fiber film for electrifying to generate 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 can be seen that the sterilization rates of the non-layered molybdenum nanosheets/graphene-based fibrous membranes prepared in examples 1-8 after being electrified are respectively over 98% for escherichia coli, candida albicans and salmonella typhimurium and over 86% for staphylococcus aureus. After the non-layered molybdenum nanosheets and the graphene are doped with each other, the non-layered molybdenum nanosheets and the graphene can be promoted to be in direct contact and doping, the non-layered molybdenum nanosheets and the graphene are prevented from being stacked or partially aggregated, the spinnability of a single two-dimensional material spinning stock solution can be improved, the non-layered molybdenum nanosheets and the graphene are mixed with dispersed carbon black powder, the mutually-doped non-layered molybdenum nanosheets and the graphene are directly adsorbed on the carbon black powder, a stable conductive network structure of the non-layered molybdenum nanosheets-graphene-carbon black particles can be formed, meanwhile, the phenomenon that the non-layered molybdenum nanosheets or the graphene layers are stacked with each other or easily generate faults (partial open circuit) under the action of external force is avoided, the number of conductive network channels is increased, the resistance is reduced, the structure of a conductive network is perfected, the conductive performance of the non-layered molybdenum nanosheets/, Long term stability. After the non-layered molybdenum 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 non-layered molybdenum 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 non-layered molybdenum nanosheets and the graphene sheet layers, a small amount of active oxygen free radicals can be generated at the heterojunction between the non-layered molybdenum nanosheets and the graphene sheet layers, and the effects of assisting sterilization and cleaning surfaces are achieved.

In contrast, the graphene-based fiber membrane prepared in comparative example 1 has a sterilization rate of 79% for escherichia coli, candida albicans and salmonella typhimurium and 52% 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 non-layered molybdenum nanosheets, so that the graphene-based fiber film has a relatively low infrared emissivity and cannot generate active radicals. The sterilization rate of the non-layered molybdenum nanosheet/graphene-based fiber membrane prepared in the comparative example 2 on escherichia coli, candida albicans and salmonella typhimurium after being electrified reaches 95%, and the sterilization rate on staphylococcus aureus only reaches 59%. Based on the fact that sufficient water bath ultrasound is not performed in the comparative example 2, graphene oxide is directly added into the pre-stripping dispersion liquid of molybdenum powder, non-layered molybdenum nanosheets can not be stripped with the assistance of graphene, and an effective non-layered molybdenum nanosheet/graphene mutual doping structure can not be formed, so that the prepared non-layered molybdenum nanosheet/graphene-based fiber film active conductor has the defects of nonuniform dispersion, low infrared emissivity, low yield of active free radicals, low antibacterial efficiency and the like. The sterilization rate of the non-layered molybdenum nanosheet/graphene-based fiber membrane prepared in the comparative example 3 on escherichia coli, candida albicans and salmonella typhimurium after being electrified is 95%, and the sterilization rate on staphylococcus aureus is only 63%. As with comparative example 2, based on that pulse probe ultrasound is not performed in comparative example 3, the non-layered molybdenum nanosheets cannot be peeled off with the assistance of graphene, and an effective non-layered molybdenum nanosheet/graphene mutual doping structure cannot be formed, resulting in the defects of non-uniform dispersion, low infrared emissivity, low yield of active free radicals, low antibacterial efficiency and the like of the prepared non-layered molybdenum nanosheet/graphene-based fibrous membrane active conductor.

(2) Infrared wavelength and normal emissivity testing

The non-layered molybdenum nanosheet/graphene-based fiber membrane or 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 standard CAS 115-. The calculation data show that the non-layered molybdenum nanosheet/graphene-based fiber membranes prepared in the examples 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 85%, the normal emissivity is over 89%, and the increase of the microcirculation blood flow of animal experiments is over 68%. 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 non-layered molybdenum nanosheet/graphene-based fibrous membrane or graphene-based fibrous membrane prepared in comparative examples 1-3 has a far infrared ray content in a 4-16 micron waveband of less than 76% (67% for the graphene-based fibrous membrane in example 1), a normal emissivity of less than 84% (75% for the graphene-based fibrous membrane in example 1), and an increase in animal experimental microcirculation blood flow of less than 62% (45% 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 non-layered molybdenum nano-sheet/graphene-based fiber film, i.e. the non-layered molybdenum nano-sheet and graphene are doped with each other, so that the uniform distribution of the electric conductor is increased, the resistance value of the fiber film is reduced, the uniformity of the spinning fiber is improved, and the like.

(3) Stability and leakage safety testing

Taking the non-layered molybdenum nanosheet/graphene-based fibrous membrane or graphene-based fibrous membrane prepared in the examples 1 to 8 and the comparative examples 1 to 3, cutting the fibrous 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 fibrous membrane into a mains supply to generate heat of the non-layered molybdenum nanosheet/graphene-based fibrous membrane or graphene-based fibrous membrane, 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 non-layered molybdenum 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.

Referring to fig. 1, insulating polymer films (for example, PET or PI) are adopted to hot-press and compound two surfaces of a non-layered molybdenum nanosheet/graphene-based fiber film or a graphene-based fiber film, and are electrified to generate heat for 90000 hours, and then are continuously electrified to generate heat 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 non-layered molybdenum nanosheet/graphene-based fibrous films 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 examples 1 and 8 showed qualified test results, indicating that the non-layered molybdenum nanosheet/graphene-based fibrous films 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 comparative examples 1 and 2 fail in temperature uniformity test and heat generation stability test, and the fiber film prepared in comparative example 3 fails in heat generation stability, and may be related to uneven dispersion of the conductor, unstable conductor under electrification and easy aging.

(4) Sheet resistance test

Taking the non-layered molybdenum nanosheet/graphene-based fibrous membrane or graphene-based fibrous membrane prepared in the examples 1 to 8 and the comparative examples 1 to 3, cutting the fibrous membrane with the blade to grow the fibrous membrane with the width of 20cm and the thickness of about 0.5mm, inserting electrodes at two ends of the fibrous membrane, and connecting the electrodes to a mains supply to generate heat for the non-layered molybdenum nanosheet/graphene-based fibrous membrane or graphene-based fibrous membrane, and carrying out the sheet resistance test. The test method is as follows: and continuously electrifying the non-layered molybdenum nanosheet/graphene-based fibrous membrane or the graphene-based fibrous membrane to generate heat, and testing the sheet resistance value of the graphene fibrous 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 non-layered molybdenum nanosheet/graphene-based fiber membranes prepared in examples 1 to 8 is relatively small (almost not more than 500 Ω/□), the variation of the sheet resistance is not obvious around the continuous energization heat generation, 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 non-layered molybdenum 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 application to electric heating equipment. The reason for this is that the dispersion of the electric conductor such as a non-layered molybdenum nanosheet or graphene may be uneven.

(5) Heat resistance and tensile Property test

Taking the non-layered molybdenum nanosheet/graphene-based fiber film or graphene-based fiber film prepared in the examples 1-8 and the comparative examples 1-3, cutting the fiber film with the blade to grow the fiber film with the width of 20cm and the thickness of about 0.5mm, and carrying out a thermal deformation temperature test according to GB/T1634-. The test results are shown in Table 9.

The prepared non-layered molybdenum 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 heat distortion temperatures of the non-layered molybdenum nanosheets/graphene-based fibrous membranes or graphene-based fibrous membranes prepared in examples 1 to 8 and comparative examples 1 to 3 exceed 250 ℃, and the fibrous membranes can meet the heat generation requirements of low-temperature, medium-temperature and medium-high-temperature heat generation equipment. The heat distortion temperature is related to the content of PI in the non-layered molybdenum nanosheet/graphene-based fibrous membrane or the graphene-based fibrous membrane. Within a certain range, the heat deformation temperature of the non-layered molybdenum nanosheet/graphene-based fibrous membrane or the graphene-based fibrous membrane is increased along with the increase of the PI content, and the good dispersion of the non-layered molybdenum nanosheet and the graphene is also beneficial to the increase of the heat deformation temperature; however, too high PI content results in too high a dope viscosity, which affects spinnability.

From the results in table 9, it is known that the tensile strength of the non-layered molybdenum nanosheets/graphene-based fiber films or graphene-based fiber films prepared in examples 1 to 8 and comparative examples 1 to 3 exceeds 60MPa, 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 PI, within a certain range, the tensile strength of the non-layered molybdenum nanosheet/graphene-based fiber membrane or the graphene-based fiber membrane is improved along with the improvement of the content of PI, and the good dispersion of the non-layered molybdenum nanosheet and graphene is also beneficial to improving the tensile strength.

(6) Test of photothermal conversion Property

The non-layered molybdenum nanosheet/graphene-based fibrous membrane or the graphene-based fibrous membrane prepared in example 4 and comparative examples 1 to 3 was cut into fibrous membranes having a length, width and thickness of 20cm and a thickness of about 0.5mm by a blade, the four fibrous membranes were placed in an illumination box equipped with a 35W HD xenon lamp (simulated sunlight), and the four fibrous membranes were spaced from the HD xenon lamp by 20cm, and the temperature change of the fibrous membranes with the increase of illumination time was tested by a temperature sensor. The test results are shown in FIG. 2.

From the results in fig. 2, it is clear that the non-layered molybdenum nanosheet/graphene-based fiber film prepared in example 4 can be rapidly heated to 62 ℃ after being irradiated with light for one minute, and can be heated to about 75 ℃ by continuous irradiation with light. The graphene-based fiber membrane prepared in comparative example 1 can be heated to 52 ℃ after being irradiated by light for one minute, and can be heated to about 60 ℃ by continuous irradiation. The non-layered molybdenum nanosheet/graphene-based fiber membrane prepared in the comparative example 2 can be heated to 59 ℃ after being irradiated by light for one minute, and can be heated to about 67 ℃ by continuous irradiation. The non-layered molybdenum nanosheet/graphene-based fiber membrane prepared in the comparative example 3 can be heated to 58 ℃ after being irradiated by light for one minute, and can be heated to about 65 ℃ by continuous irradiation. Therefore, the non-layered molybdenum 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, physical therapy and clothing, integrates the generation of heat by electricity and the generation of heat by light and heat, 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

1. The non-layered molybdenum nanosheet/graphene-based heating film is characterized by comprising a first transparent insulating layer, an electrode, a second transparent insulating layer and a non-layered molybdenum nanosheet/graphene-based fibrous membrane, wherein the first transparent insulating layer covers one surface of the non-layered molybdenum nanosheet/graphene-based fibrous membrane, the second transparent insulating layer covers the other surface of the non-layered molybdenum nanosheet/graphene-based fibrous membrane, one end of the electrode is electrically connected with the non-layered molybdenum nanosheet/graphene-based fibrous membrane, and the other end of the electrode extends out of the first transparent insulating layer or the second transparent insulating layer;

2. The non-layered molybdenum nanoplatelet/graphene-based heating film of claim 1, wherein a transparent heat conducting layer is further disposed between the second transparent insulating layer and the non-layered molybdenum nanoplatelet/graphene-based fiber film.

3. The non-layered molybdenum nano-sheet/graphene-based heating film according to claim 2, wherein a waterproof adhesive layer is further disposed between the first transparent insulating layer and the second transparent insulating layer, and the waterproof adhesive layer is respectively bonded to the first transparent insulating layer and the second transparent insulating layer to form a closed cavity;

the non-layered molybdenum nanosheet/graphene-based fiber membrane and the transparent heat conduction layer are both arranged in the closed cavity, and the electrode extends out of the closed cavity.

4. A non-laminar molybdenum nano-sheet/graphene-based heating film according to claim 3, wherein the electrode comprises interconnected lateral and vertical arms, the lateral arms extending from the transparent heat conductive layer out of the closed cavity, and the vertical arms extending from the transparent heat conductive layer and being electrically connected to the non-laminar molybdenum nano-sheet/graphene-based fiber film.

5. The non-layered molybdenum nanoplate/graphene-based heating film according to claim 4, further comprising a heat reflecting layer provided in a concave shape to form an accommodation groove;

the first transparent insulating layer and the non-layered molybdenum nanosheet/graphene-based fiber film are arranged in the accommodating groove.

6. The non-layered molybdenum nanoplate/graphene-based heat generating film according to claim 5, wherein the heat reflecting layer includes a reflecting film and an insulating film, the reflecting film covering an outer surface of the insulating film;

the insulating film is equipped with the flange towards the one end of second transparent insulation layer, be equipped with the draw-in groove that is used for the holding flange on the periphery wall of waterproof adhesive linkage.

7. The non-layered molybdenum nano sheet/graphene-based heating film according to claim 1, wherein in the step of preparing the non-layered molybdenum nano sheet/graphene oxide dispersion liquid, the mass-to-volume ratio of the mixture of molybdenum powder and graphene oxide to N-methyl pyrrolidone is 1-10 mg/ml, the time of pulse probe ultrasound is 2-12 h, the power of the pulse probe ultrasound is 200-300W, and the frequency of the pulse probe ultrasound is set as follows: ultrasound 5s, interval 5 s.

8. The non-layered molybdenum nanosheet/graphene-based heating film according to claim 1, wherein in the step of preparing the non-layered molybdenum nanosheet/graphene oxide dispersion liquid, after the ultrasound is finished, the mixed liquid is concentrated by a vacuum rotary evaporation method until the concentration of 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 45-55 ℃.

9. The non-layered molybdenum nanoplate/graphene-based heating film according to claim 1, wherein in the spinning step, the mass-to-volume ratio of the carbon black to the non-layered molybdenum nanoplate/graphene oxide dispersion is 20 to 50 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 to collect the non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber by adopting a collecting plate.

10. The non-layered molybdenum nano-sheet/graphene-based heating film according to claim 1, wherein in the post-treatment step, the non-layered molybdenum nano-sheet/graphene oxide hybrid porous fiber film is washed with deionized water for 1-3 times, and the non-layered molybdenum nano-sheet/graphene oxide hybrid porous fiber film is transferred to a vacuum drying oven at 60-85 ℃ for drying for 4-12 h;

and (3) soaking the dried non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane in any one of HI, NaBH4, hydrazine hydrate and ascorbic acid for reduction to prepare the non-layered molybdenum nanosheet/graphene-based fiber membrane.