Poly (p-phenylene benzobisoxazole) nanofiber composite hydrogel photo-thermal evaporator as well as preparation method and application of poly (p-phenylene benzobisoxazole) nanofiber composite hydrogel photo-thermal evaporator

Abstract

The invention discloses a poly (p-phenylene benzobisoxazole) nanofiber composite hydrogel photo-thermal evaporator and a preparation method and application thereof.The photo-thermal evaporator is composed of a photo-thermal conversion assembly and a heat insulation supporting assembly, and the photo-thermal conversion assembly is made of PBO nanofiber composite hydrogel; the bottom of the photo-thermal conversion assembly is embedded in the heat insulation supporting assembly. The interface water evaporation-oriented PBO nanofiber composite hydrogel is prepared by a simple sol-gel method, and the preparation process is simple. The PBO nanofibers and the polyvinyl alcohol are tightly combined to form an ultra-strong structure evaporator, the wettability of the material is improved due to the addition of the PVA, and the abundant three-dimensional network and porous structure provide guarantee for water transmission. The photo-thermal evaporator can serve as a main assembly of a solar interface water evaporation device, can obtain energy from the environment, has excellent interface water evaporation performance and meanwhile has good mechanical performance and tolerance.

Description

Technical Field

[0001] The present invention belongs to the field of solar-driven interfacial water evaporation, and relates to a solar-driven interfacial water evaporation device, specifically to a poly(p-phenylene benzobisoxazole) (abbreviated as PBO) nanofiber composite hydrogel photothermal evaporator for solar interfacial water evaporation, its preparation method, and its application in solar-driven interfacial water evaporation. Background Art

[0002] Solar-driven Interfacial Water Evaporation (SIWE) is a technology that localizes solar energy at the gas-liquid interface through a photothermal material, selectively heating the water molecules in the evaporation layer rather than the entire water body. Its core lies in using a photothermal conversion material to absorb solar energy and convert it into heat energy, restricting the heat at the evaporation interface through micro-nano structure design, reducing the heat diffusion to the water body, thereby improving the evaporation efficiency to alleviate water resource shortage. For the core component, the photothermal material, its materials are widely sourced, covering carbon-based materials, semiconductors, metal plasmas, etc., and even natural materials (wood, mushroom carbon) can be combined with inexpensive synthesis processes (such as salt-impregnated foam). The water evaporation performance can be further improved through composite design (such as MXene / wood). In addition to seawater desalination, SIWE can also be used for wastewater treatment, resource recovery (such as lithium and uranium extraction), hydrogen production, and agricultural irrigation, combined with photovoltaic and thermoelectric modules to achieve energy-water co-production. There are still some problems to be solved in solar-driven interfacial water evaporation, such as the efficiency bottleneck; it is easy to cause material fouling in the face of complex water sources, resulting in reduced durability; laboratory-level equipment is difficult to meet industrial requirements and difficult to achieve large-scale application; it is restricted in some specific extreme environment applications, etc.

[0003] As a reinforcing agent, PBO fiber has significant performance advantages and technical significance in the field of composite materials. On the one hand, PBO fiber has ultra-high mechanical strength (5.8 GPa) and thermal stability (decomposition temperature 650 °C), and its three-dimensional network structure is expected to be used as the skeleton material of the composite evaporator, significantly improving the mechanical strength and high-temperature resistance of the evaporator; on the other hand, the chemical corrosion resistance of PBO (resistant to strong acids and strong alkalis) makes it expected to be applicable to complex water source environments (such as high-salt seawater, oily wastewater) and extreme environments (such as high temperature, high humidity, ultraviolet radiation). Summary of the Invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a preparation method and application of a poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator. This photothermal evaporator can be used as the main component of a solar interfacial water evaporation device, can obtain energy from the environment, has excellent interfacial water evaporation performance, and at the same time has good mechanical properties and tolerance.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] A poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator is composed of a photothermal conversion component and a heat insulation and support component;

[0007] The photothermal conversion component is made of PBO nanofiber composite hydrogel;

[0008] The PBO nanofiber composite hydrogel is composed of a three-dimensional network framework formed by PBO nanofibers and polyvinyl alcohol, and photothermal conversion micro-nano materials adsorbed on the three-dimensional network framework;

[0009] The heat insulation and support component is made of polystyrene foam, and is used to fix the photothermal conversion component and make it float on the water surface;

[0010] The bottom of the photothermal conversion component is embedded inside the heat insulation and support component;

[0011] The photothermal conversion micro-nano materials are carboxylated carbon nanotubes, carbon nanotubes, reduced graphene oxide nanosheets, graphene oxide nanosheets, etc.

[0012] A preparation method of the above poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator includes the following steps:

[0013] Step S1: Add the photothermal conversion micro-nano materials into a mixed acid of trifluoroacetic acid (TFA) and methanesulfonic acid (MSA), and perform magnetic stirring in cooperation with ultrasonic-assisted dispersion to obtain a mixed acid dispersion liquid of the photothermal conversion micro-nano materials, wherein: the time of magnetic stirring is 3 to 6 hours, the ultrasonic time is 1 to 2 hours, the volume ratio of trifluoroacetic acid to methanesulfonic acid is 1 to 4:1, and the content of the photothermal conversion micro-nano materials is 0.2 to 0.8% w / v;

[0014] Step S2: Add a predetermined amount of PBO fibers into the mixed acid dispersion liquid in Step S1, and perform magnetic stirring in cooperation with ultrasonic-assisted dispersion to obtain a mixed acid dispersion liquid of PBO nanofibers (PBONF) / photothermal conversion micro-nano materials, wherein: the time of magnetic stirring is 12 to 24 hours, the ultrasonic time is 0.5 to 2 hours, and the content of PBO fibers is 0.2 to 0.4% w / v;

[0015] Step S3: Weigh a certain amount of polyvinyl alcohol (PVA) and add it to TFA under magnetic stirring to obtain a PVA acid solution, wherein: the time of magnetic stirring is 12 to 20 hours, and the content of PVA is 5 to 7% w / v;

[0016] Step S4, preheating the PBO nanofiber / photothermal conversion micro-nano material dispersion prepared in step S2 and the PVA acid solution prepared in step S3 in a water bath, mixing them in equal volumes, shaking them vigorously for a certain period of time, and immediately pouring them into a mold, aging them at room temperature to release bubbles formed during the mixing process while ensuring complete gelation, wherein: the water bath temperature is 45 to 55° C., the water bath time is 20 to 40 minutes, the vigorous shaking time is 20 to 30 seconds, and the aging time is 12 to 24 hours;

[0017] Step S5, immersing the material obtained in step S4 in a large amount of pure water for solvent exchange to obtain a PBO nanofiber composite hydrogel;

[0018] Step S6: using the composite hydrogel obtained in step S5 as a photothermal conversion component and assembling it with a thermal insulation support component to form a photothermal evaporator.

[0019] The above-mentioned poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator can be used in solar-driven interfacial water evaporation. As the main component of the solar interfacial water evaporation device, it can obtain energy from the environment, has excellent interfacial water evaporation performance, and has good mechanical properties and tolerance to different environments and water sources.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The evaporator with a three-dimensional columnar structure provides a larger surface area for water evaporation. Compared with the flat interface evaporator, water evaporation in the columnar evaporator can occur simultaneously on the side. Water evaporation absorbs heat, which will inevitably take away some heat, causing the temperature on the side of the evaporator to drop, making it possible for the local temperature to be lower than the ambient temperature, creating conditions for the evaporator to obtain energy from the environment.

[0022] 2. The present invention prepares a PBO nanofiber composite hydrogel for interfacial water evaporation by a simple sol-gel method, and the preparation process is simple. PBO nanofibers are tightly combined with polyvinyl alcohol to form an ultra-strong structural evaporator. The wettability of the bottom of the material is improved by the addition of PVA. The rich three-dimensional network and porous structure provide a guarantee for water transmission. Due to the interaction between water molecules and hydrophilic functional groups on the polymer network, there are three types of water molecules in the hydrogel, among which the intermediate water has a lower evaporation enthalpy, which can reduce the energy required for water evaporation.

[0023] 3. The doped carbon nanomaterials enhance the hydrophilicity of the evaporator, and also greatly increase the light absorption rate and photothermal evaporation efficiency of the evaporator.

[0024] 4. The PBO nanofibers construct a high-temperature resistant barrier in the three-dimensional network framework of the interfacial evaporator due to their extremely high thermal decomposition temperature, improving the thermal stability of the evaporator to a certain extent. At the microscopic level, the interfacial binding force is enhanced through hydrogen bonding and mechanical interlocking mechanisms, significantly optimizing the compression resistance performance of the evaporator. Meanwhile, it effectively avoids the performance degradation caused by the structural collapse of traditional evaporators. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of the PBO nanofiber composite hydrogel columnar photothermal evaporator;

[0026] Figure 2 is a scanning electron microscope photograph of the PBO nanofiber composite hydrogel evaporator;

[0027] Figure 3 is the mechanical property curve of the PBO nanofiber composite hydrogel evaporator;

[0028] Figure 4 is the water mass loss diagram during the vapor generation experiment of the PBO nanofiber composite hydrogel evaporator under 1 sun illumination;

[0029] Figure 5 is the water evaporation cycle stability diagram of the PBO nanofiber composite hydrogel evaporator.

[0030] In the figure: 1: Photothermal conversion component; 2: Thermal insulation support component. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The technical solutions of the present invention will be further described below in conjunction with the embodiments, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the protection scope of the present invention.

[0032] Raw materials and reagents: PBO fibers (AS, 500D / 330f) are from Zhongke Jinqi New Materials Technology Co., Ltd. Carbon nanomaterials are purchased from Jiangsu Xianfeng Nanomaterials Co., Ltd. Trifluoroacetic acid (TFA, 99.5%), methanesulfonic acid (MSA, 99%), and polyvinyl alcohol (17 - 99 type) are purchased from Beijing Innochem Science & Technology Co., Ltd.

[0033] Example 1

[0034] This example provides a poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator, as Figure 1As shown in the figure, the photothermal evaporator is composed of a photothermal conversion component 1 and a heat insulation support component 2; the photothermal conversion component 1 is a PBO nanofiber composite hydrogel with a columnar structure; the PBO nanofiber composite hydrogel is composed of a three-dimensional network skeleton composed of PBO nanofibers and polyvinyl alcohol, and photothermal conversion micro-nano materials adsorbed on the three-dimensional network skeleton; the heat insulation support component is a polystyrene ring-shaped foam heat insulation support component, and the bottom of the photothermal conversion component is embedded in the ring to form a columnar photothermal evaporator.

[0035] Example 2

[0036] This example provides a preparation method of a poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator, and the method includes the following steps:

[0037] Step S1: Add 0.8% w / v of carboxylated carbon nanotubes (CCNT) to a mixed solution of TFA:MSA (1:1 v / v), and stir for 3 hours to obtain a CCNT mixed acid dispersion.

[0038] Step S2: Add 0.2% w / v of PBO to the CCNT mixed acid solution, stir for 2 hours, and ultrasonicate for 1 hour to prepare a PBONF / CCNT mixed acid dispersion.

[0039] Step S3: Weigh 6% w / v of PVA and add it to TFA under magnetic stirring, and stir for 12 hours to obtain a PVA acid solution.

[0040] Step S4: Preheat the PBONF / CCNT dispersion prepared in step S2 and the PVA acid solution prepared in step S3 in a 50°C water bath, then mix them in equal volumes, shake vigorously for about 30 s, and immediately pour them into a dish-shaped mold, and place them at room temperature for 1 day to release the bubbles formed during the mixing process and ensure complete gelation.

[0041] Step S5: Immerse the material obtained in step S4 in a large amount of pure water for 3 days, and change the water every 6 hours for solvent exchange to obtain a composite hydrogel.

[0042] Step S6: Use the composite hydrogel obtained in step S5 as the photothermal conversion component, and assemble it with a polystyrene heat insulation support component to form a photothermal evaporator.

[0043] Example 3

[0044] This example provides a preparation method of a poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator, and the method includes the following steps:

[0045] Step S1: Add 0.4% w / v of CCNT into the mixed solution of TFA:MSA (1:1 v / v), stir for 4 hours to obtain the CCNT mixed acid dispersion.

[0046] Step S2: Add 0.4% w / v of PBO into the CCNT mixed acid solution, stir for 1 day and sonicate for 1 hour to prepare the PBONF / CCNT mixed acid dispersion.

[0047] Step S3: Weigh 7% w / v of PVA and add it into TFA under magnetic stirring, stir for 18 hours to obtain the PVA acid solution.

[0048] Step S4: Preheat the PBONF / CCNT dispersion prepared in Step S2 and the PVA acid solution prepared in Step S3 in a 50°C water bath, then mix them in equal volumes, shake vigorously for about 30 s, and immediately pour them into a cylindrical mold, and let it stand at room temperature for 12 hours to release the bubbles formed during the mixing process and ensure complete gelation.

[0049] Step S5: Immerse the material obtained in Step S4 in a large amount of pure water for 3 days, change the water every 6 hours for solvent exchange to obtain the composite hydrogel.

[0050] Step S6: Use the composite hydrogel obtained in Step S5 as the photothermal conversion component and assemble it with the polystyrene thermal insulation support component to form the photothermal evaporator.

[0051] Example 4

[0052] This example provides a method for preparing a poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator, and the method includes the following steps:

[0053] Step S1: Add 0.4% w / v of reduced graphene oxide (rGO) into the mixed solution of TFA:MSA (1:1 v / v), stir for 6 hours to obtain the rGO mixed acid dispersion.

[0054] Step S2: Add 0.3% w / v of PBO into the rGO mixed acid solution, stir for 1 day and sonicate for 0.5 hour to prepare the PBONF / rGO mixed acid dispersion.

[0055] Step S3: Weigh 6% w / v of PVA and add it into TFA under magnetic stirring, stir for 12 hours to obtain the PVA acid solution.

[0056] Step S4: Preheat the PBONF / rGO dispersion prepared in Step S2 and the PVA acid solution prepared in Step S3 in a 50°C water bath, then mix them in equal volumes, shake vigorously for about 30 s, and immediately pour them into a cylindrical mold, and let it stand at room temperature for 1 day to release the bubbles formed during the mixing process and ensure complete gelation.

[0057] Step S5: Immerse the material obtained in Step S4 in a large amount of pure water for 3 days, and replace the water every 6 hours for solvent exchange to obtain a composite hydrogel.

[0058] Step S6: Use the composite hydrogel obtained in Step S5 as a photothermal conversion component and assemble it with a polystyrene thermal insulation support component to form a photothermal evaporator.

[0059] Example 5

[0060] This example provides a method for preparing a poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator, and the method includes the following steps:

[0061] Step S1: Add 0.8% w / v of graphene oxide (GO) to a mixed solution of TFA:MSA (1:1 v / v), and stir for 6 hours to obtain a GO mixed acid dispersion.

[0062] Step S2: Add 0.4% w / v of PBO to the GO mixed acid solution, stir for 1 day, and ultrasonicate for 2 hours to prepare a PBONF / GO mixed acid dispersion.

[0063] Step S3: Weigh 6% w / v of PVA and add it to TFA under magnetic stirring, and stir for 12 hours to obtain a PVA acid solution.

[0064] Step S4: Preheat the PBONF / GO mixed acid dispersion prepared in Step S2 and the PVA acid solution prepared in Step S3 in a 50°C water bath, then mix them in equal volumes, shake vigorously for about 30 s, and immediately pour them into a cylindrical mold, and let it stand at room temperature for 12 hours to release the bubbles formed during the mixing process and ensure complete gelation.

[0065] Step S5: Immerse the material obtained in Step S4 in a large amount of pure water for 3 days, and replace the water every 6 hours for solvent exchange to obtain a composite hydrogel.

[0066] Step S6: Use the composite hydrogel obtained in Step S5 as a photothermal conversion component and assemble it with a polystyrene thermal insulation support component to form a photothermal evaporator.

[0067] Example 6

[0068] This example provides a method for preparing a poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator, and the method includes the following steps:

[0069] Step S1: Add 0.6% w / v of carbon nanotubes (CNT) to a mixed solution of TFA:MSA (1:1 v / v), and stir for 6 hours to obtain a CNT mixed acid dispersion.

[0070] Step S2: Add 0.4% w / v of PBO into the CNT mixed acid solution, stir for 1 day, and ultrasonicate for 1 hour to obtain the PBONF / CNT mixed acid dispersion.

[0071] Step S3: Weigh 6% w / v of PVA and add it to TFA under magnetic stirring, stir for 12 hours to obtain the PVA acid solution.

[0072] Step S4: Preheat the PBONF / CNT dispersion prepared in Step S2 and the PVA acid solution prepared in Step S3 in a 50°C water bath, then mix them in equal volumes, shake vigorously for about 30 s, and immediately pour them into a cylindrical mold. Let it stand at room temperature for 1 day to release the bubbles formed during the mixing process and ensure complete gelation.

[0073] Step S5: Immerse the obtained material in a large amount of pure water for 3 days, change the water every 6 hours for solvent exchange to obtain the composite hydrogel.

[0074] Step S6: Use the composite hydrogel obtained in Step S5 as the photothermal conversion component and assemble it with the polystyrene thermal insulation support component to form the photothermal evaporator.

[0075] Comparative Example 1

[0076] Step S1: Add 0.4% w / v of CCNT into the mixed solution of TFA:MSA (1:1 v / v), stir for 6 hours, and ultrasonicate for 1 hour to obtain the CCNT mixed acid dispersion.

[0077] Step S2: Weigh 6% w / v of PVA and add it to TFA under magnetic stirring, stir for 12 hours to obtain the PVA acid solution.

[0078] Step S3: Preheat the mixed acid solution prepared in Step S1 and the PVA acid solution prepared in Step S2 in a 50°C water bath, then mix them in equal volumes, shake vigorously for about 20 s, and immediately pour them into a dish-shaped mold. Let it stand at room temperature for 1 day to release the bubbles formed during the mixing process and ensure complete gelation.

[0079] Step S4: Immerse the material obtained in Step S3 in a large amount of pure water for 3 days, change the water every 6 hours for solvent exchange to obtain the PVA / CCNT hydrogel.

[0080] Step S5: Use the composite hydrogel obtained in Step S4 as the photothermal conversion component and assemble it with the polystyrene thermal insulation support component to form the photothermal evaporator.

[0081] Use Example 2 and conduct the following tests to verify the beneficial effects of the present invention:

[0082] Test 1: Morphology Characterization of PBO Nanofiber Composite Hydrogel

[0083] To observe the microstructure and pore size distribution of the material, a composite hydrogel sample was taken and pre-frozen in a -20°C refrigerator for 12 hours, and then freeze-dried for 24 hours to minimize the collapse of the gel structure caused by uneven stress distribution due to different drying rates. The scanning electron microscope (SEM) image of the composite hydrogel is as Figure 2 shown. The SEM image shows that the hydrogel has rich and uniformly distributed three-dimensional internal channels, which can ensure the stable transmission of water. It can be seen from the figure that the pore sizes of the three gels are roughly distributed in the range of 1.4 - 1.8 μm.

[0084] Experiment 2: Compressive properties of PBO nanofiber composite hydrogel

[0085] To further study the compressive properties of the composite hydrogel, the change of compressive stress with strain was measured through plane compression tests, and the stress-strain curve is as Figure 3 shown. From the stress-strain curve of PVA / CCNT, it can be seen that at the same strain, the stress value is lower, indicating that its compressive resistance is weaker. For the PBO nanofiber composite hydrogel, due to the addition and reinforcement of PBONF, the stress value of the composite hydrogel increases significantly. The PBO nanofiber composite hydrogel has a higher elastic modulus and greater rigidity. The PBO nanofiber composite hydrogel shows better toughness when compressed, can absorb more energy and is not easily damaged. This indicates that the addition of PBONF in the present invention significantly enhances the mechanical properties of the hydrogel solar thermal evaporator.

[0086] Experiment 3: Solar interfacial water evaporation performance test of PBO nanofiber composite hydrogel evaporator

[0087] The mass change of the evaporator system dependent on the illumination time was carefully recorded by an electronic balance to study the solar interfacial water evaporation performance of the composite aerogel, and the experimental results are as Figure 4 shown. After being irradiated at one sun illumination intensity for 1 hour, the mass loss of the water evaporation system of the composite hydrogel reached 1.25 g. To more clearly show the evaporation performance of the hydrogel, through linear fitting, the evaporation value was estimated using the slope of the mass loss-time curve at steady state, and the evaporation rate reached 2.01 kg·m -2 ·h -1 .

[0088] Experiment 4: Cyclic stability analysis of PBO nanofiber composite hydrogel evaporator

[0089] To investigate the cyclic stability of the hydrogel, the composite hydrogel was subjected to 14 consecutive evaporation cycle tests under standard sunlight intensity (1 sun equivalent). As Figure 5As shown, the evaporator maintains an evaporation efficiency of 1.3 kg·m -2 ·h -1 or higher in each cycle, which fully verifies its excellent cycle stability. The long-term use of the material can significantly extend the service life of the evaporation device. By reducing the number of maintenance and replacement frequencies, it not only reduces the amount of waste generated, but also saves the treatment cost, thus achieving a double improvement in environmental friendliness and economic benefits.

Claims

1. A poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator, characterized in that The photothermal evaporator is composed of a photothermal conversion component and a heat insulation support component; The photothermal conversion component is made of PBO nanofiber composite hydrogel; The PBO nanofiber composite hydrogel is composed of a three-dimensional network skeleton composed of PBO nanofibers and polyvinyl alcohol, and photothermal conversion micro-nano materials adsorbed on the three-dimensional network skeleton; The bottom of the photothermal conversion component is embedded inside the heat insulation support component.

2. The poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator according to claim 1, wherein The photothermal conversion micro-nano materials are carboxylated carbon nanotubes, carbon nanotubes, reduced graphene oxide nanosheets or graphene oxide nanosheets.

3. The poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator according to claim 1, wherein The heat insulation support component is made of polystyrene foam.

4. The poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator according to claim 1, wherein The photothermal conversion component is in a columnar structure, and the heat insulation support component is in an annular structure.

5. A method for preparing the poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator according to any one of claims 1-4, characterized in that The method includes the following steps: Step S1: Add the photothermal conversion micro-nano materials into a mixed acid of trifluoroacetic acid and methanesulfonic acid, and disperse them by magnetic stirring combined with ultrasonic assistance to obtain a mixed acid dispersion liquid of the photothermal conversion micro-nano materials, where: the content of the photothermal conversion micro-nano materials is 0.2 - 0.8% w / v; Step S2: Add PBO fibers into the mixed acid dispersion liquid obtained in Step S1, and disperse them by magnetic stirring combined with ultrasonic assistance to obtain a mixed acid dispersion liquid of PBO nanofibers / photothermal conversion micro-nano materials, where: the content of PBO fibers is 0.2 - 0.4% w / v; Step S3: Weigh polyvinyl alcohol and add it to trifluoroacetic acid under magnetic stirring to obtain a PVA acid solution, where: the content of PVA is 5 - 7% w / v; Step S4: Preheat the PBO nanofiber / photothermal conversion micro-nano material dispersion liquid prepared in Step S2 and the PVA acid solution prepared in Step S3 in a water bath and then mix them in equal volumes. After shaking vigorously, immediately pour them into a mold and age at room temperature; Step S5: Immerse the material obtained in Step S4 in a large amount of pure water for solvent exchange to obtain a PBO nanofiber composite hydrogel; Step S6: Use the composite hydrogel obtained in Step S5 as the photothermal conversion component and assemble it with the heat insulation support component to form a photothermal evaporator.

6. The preparation method of the poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator according to claim 5, characterized in that In Step S1, the time of magnetic stirring is 3 - 6 hours, the ultrasonic time is 1 - 2 hours, and the volume ratio of trifluoroacetic acid to methanesulfonic acid is 1 - 4:

1.

7. The preparation method of the poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator according to claim 5, characterized in that In Step S2, the time of magnetic stirring is 12 - 24 hours, and the ultrasonic time is 0.5 - 2 hours.

8. The preparation method of the poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator according to claim 5, characterized in that In Step S3, the time of magnetic stirring is 12 - 20 hours.

9. The preparation method of the poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator according to claim 5, characterized in that In Step S4, the temperature of the water bath is 45 - 55 °C, the water bath time is 20 - 40 minutes, the time of vigorous shaking is 20 - 30 seconds, and the aging time is 12 - 24 hours.

10. Application of the poly(p-phenylene benzobisoxazole) nanofiber composite hydrogel photothermal evaporator according to any one of claims 1 - 4 in a solar interfacial water evaporation device.

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