Pattern-on-ball photo-thermal evaporation material, preparation method thereof and photo-thermal evaporation device with honeycomb-shaped hollow structure

Abstract

The invention belongs to the technical field of photo-thermal conversion and solar seawater desalination, and particularly relates to a flower-on-ball photo-thermal evaporation material, a preparation method of the flower-on-ball photo-thermal evaporation material and a photo-thermal evaporation device of a honeycomb-shaped hollow structure. The photothermal evaporation device of the honeycomb-shaped hollow structure comprises a base and an evaporation assembly fixed to the base, the evaporation assembly comprises an internal T-shaped evaporation body and an external cylindrical wrapping part, and the T-shaped evaporation body and / or the cylindrical wrapping part are / is made of photothermal evaporation materials. The whole device is made of photo-thermal evaporation materials and PVA-PAM composite aerogel, the upper portion of a T-shaped main body is a honeycomb-shaped disc evaporation layer, the lower portion of the T-shaped main body is a water supply column, an outer cylinder and the water supply column form a hollow cavity, and salt is discharged through a T-shaped path. The device optimizes heat management, improves the water evaporation rate and the long-term stability of seawater desalination through material and structure collaboration, and is suitable for solar seawater desalination and brackish water desalination.

Description

Technical Field

[0001] This invention belongs to the field of photothermal conversion and solar seawater desalination technology, specifically relating to a spherical flower photothermal evaporation material, its preparation method, and a honeycomb hollow structure photothermal evaporation device. Background Technology

[0002] With the increasing severity of the global freshwater shortage, solar-driven photothermal evaporation technology has become an important approach for seawater desalination and brackish water desalination. Existing solar evaporators typically employ a single-layer light-absorbing structure, where photothermal materials are loaded onto a porous substrate surface, achieving interfacial evaporation through localized heating. However, this type of structure generally suffers from the following problems: 1) The photothermal layer is only located on the evaporation surface, making it difficult for heat to be fully transferred to the interior, resulting in excessively high top temperature, severe heat loss to the environment, and low system energy utilization. 2) The evaporation surface is singular, and evaporation only occurs on the outer surface, while the internal cavity or pores fail to effectively participate in heat utilization; 3) During long-term evaporation, salt accumulates at the evaporation interface, which can easily cause crystallization blockage and evaporation performance degradation; 4) Traditional photothermal materials, such as single carbon-based or metal sulfide materials, have limited light absorption bands and low thermal conductivity, making it difficult to achieve efficient light absorption and rapid heat distribution. 5) Most structures are planar or block-shaped, lacking a reasonable three-dimensional water supply channel design, and cannot take into account the coordinated regulation of light absorption, heat management and anti-salt crystallization.

[0003] Therefore, there is an urgent need for a photothermal evaporation material and device structure that combines broad-spectrum light absorption, efficient thermal management, multi-interface evaporation, and anti-salt crystallization capabilities to improve solar energy utilization and long-term operational stability of seawater desalination. Summary of the Invention

[0004] The purpose of this invention is to provide a spherical flower-shaped photothermal evaporation material, its preparation method, and a honeycomb hollow structure photothermal evaporation device to solve problems such as insufficient light absorption, severe heat loss, and salt blockage in existing photothermal evaporation systems. This technical solution is applicable to water resource treatment scenarios such as solar-driven seawater desalination and brackish water desalination.

[0005] The technical solution provided by this invention is as follows: A photothermal evaporation material with floral patterns on spheres includes carbon spheres, the surface of which is coated with a high specific surface area molybdenum disulfide nanoflower layer with a specific surface area greater than 20 m². 2 / g.

[0006] Specifically, the carbon spheres have a spherical structure.

[0007] Specifically, the molybdenum disulfide is a nanoflower structure with a size of 200-300 nm formed from dense molybdenum disulfide nanosheets.

[0008] Specifically, the specific surface area of ​​the molybdenum disulfide is 20–80 m² / g.

[0009] Specifically, the mass ratio of molybdenum disulfide to carbon spheres is 1.0-1.5:1.0.

[0010] Based on the above technical solution, the spherical flower photothermal evaporation material uses 6-8 μm carbon spheres as the core, on which 200-300 nm three-dimensional flower-like molybdenum disulfide (MoS2) nanosheets are grown in situ. The carbon spheres serve as the thermally conductive core, while the MoS2 nanoflowers provide high specific surface area and broad-spectrum absorption characteristics. Together, they form a core-shell integrated photothermal composite unit, significantly improving solar light absorption and photothermal conversion efficiency. When mixed with PVA-PAM composite aerogel, this photothermal material forms a porous composite network with excellent thermal management performance and capillary water transport capabilities.

[0011] The present invention also provides a method for preparing the aforementioned photothermal evaporation material, comprising the following steps: 1) Preparation of spherical carbon spheres: Glucose was dissolved in deionized water to form an aqueous solution with a concentration of 0.1-0.2 mol / L. The solution was then transferred to a high-pressure reactor and hydrothermally reacted at 160-180℃ for 8-12 hours at a pressure of 4-8 MPa. After the reaction, the solution was centrifuged, washed, and vacuum dried at 60-80℃ for 4-6 hours to obtain spherical carbon spheres with a size of 6-8 μm. 2) Preparation of carbon spheres coated with molybdenum disulfide nanoflowers: Carbon spheres were dispersed in a mixed aqueous solution of ammonium molybdate and thiourea. After ultrasonic dispersion, the mixture was transferred to a high-pressure reactor and hydrothermally reacted at 180-220℃ for 12-24 hours at a pressure of 7-15 MPa. After reaction, the mixture was centrifuged, washed, and vacuum dried at 60-80℃ for 6-8 hours to obtain carbon spheres coated with molybdenum disulfide nanoflowers, denoted as C@MoS2. The molar ratio of carbon spheres, ammonium molybdate, and thiourea was (60-100):1:(30-50), and the carbon sphere dispersion concentration was 6-8 g / L.

[0012] The present invention also provides a photothermal evaporation material, which is prepared by the following method: the aforementioned *Pterocarya stenoptera* photothermal evaporation material, PVA, PAM and an appropriate amount of crosslinking agent are prepared into a composite gel liquid, which is then cast and freeze-dried to form a honeycomb structure aerogel with through holes, thereby obtaining the photothermal evaporation material, wherein: the mass ratio of the *Pterocarya stenoptera* photothermal evaporation material, PVA and PAM is (0.25-0.5):5:(0.25-1); the amount of crosslinking agent added is 1%-5% of the total mass of PVA and PAM.

[0013] The present invention also provides a honeycomb hollow structure photothermal evaporation device, comprising: Base; And an evaporation assembly fixed on the base, the evaporation assembly including an inner T-shaped evaporation body and an outer cylindrical covering, wherein the material of the T-shaped evaporation body and / or the cylindrical covering is selected from the photothermal evaporation material.

[0014] The device is constructed entirely of photothermal evaporation materials and PVA-PAM composite aerogel. The upper part of the T-shaped main body is a honeycomb-shaped disc evaporation layer, and the lower part is a water supply column. The outer cylinder and the water supply column form a hollow cavity, through which salt is discharged via a T-shaped path. This device optimizes thermal management through synergistic material and structural design, improving the water evaporation rate and long-term stability of seawater desalination. It is suitable for solar-powered seawater desalination and brackish water desalination.

[0015] Specifically: The T-shaped evaporator body includes an upper disc evaporation layer and a lower vertical water supply column; A hollow cavity is formed between the outer cylindrical covering and the vertical water supply column, and the sidewall of the hollow cavity constitutes the inner wall evaporation interface; The end of the vertical water supply column away from the evaporation layer of the disc is fixed to the base, forming a T-shaped water supply and salt discharge channel.

[0016] Based on the above technical solution, the T-shaped evaporator body consists of a honeycomb-shaped disc evaporation layer on the upper part and a vertical water supply column on the lower part, which are integrally formed. The disc evaporation layer has multiple through holes (2-5 mm in diameter, 4-8 in number) distributed in a honeycomb pattern to enhance air convection and steam discharge. An external cylindrical covering is fitted onto the outside of the water supply column, forming a hollow cavity. This cavity serves as insulation and as the evaporation interface for the inner wall. When the device is working, the disc layer absorbs sunlight and its temperature rises. The heat is transferred to the inside of the cavity through thermal radiation and natural convection, raising the temperature of the air inside the cavity and driving evaporation on the inner wall, thus constructing a "dual evaporation" system, effectively reducing surface heat loss and improving the utilization rate of light and heat.

[0017] In addition, the T-shaped water supply path allows the liquid to be transported from bottom to top and diffused outward in the disc layer, and the salt is carried away from the main evaporation area to the outer edge area, achieving self-cleaning and long-term prevention of salt crystallization.

[0018] At 1 sun (1 kW·m -2 Under standard sunlight conditions, the pure water evaporation rate of the device of this invention can reach 3.11 kg·m³. -2 ·h -1 This is significantly higher than that of traditional surface evaporators. For actual Bohai Sea water, its evaporation rate is 2.85 kg·m³. -2 ·h -1It exhibits excellent salt tolerance and operational stability; even in a high-concentration 20 wt% NaCl solution, it still maintains a stability of 1.61 kg·m³. -2 ·h -1 The high efficiency of evaporation demonstrates that the device of the present invention has excellent anti-salt crystallization ability and long-term working stability.

[0019] Preferably, in the disc evaporation layer, the thickness of the disc is 5-10 mm, the diameter of the through hole is 2-5 mm, the distance between the through hole and the center of the disc is 10-15 mm, and the number of through holes is 4-8.

[0020] Preferably, the inner diameter of the hollow cavity is 14-16 mm, the outer diameter of the hollow cavity is 20-30 mm, and the wall thickness of the outer cylindrical covering is 6-10 mm.

[0021] Specifically, the base is made of polystyrene foam; Specifically, the vertical water supply column is inserted into the base to a depth of 0.3-1cm; Specifically, the mass percentage of the spherical flower photothermal evaporation material in the honeycomb hollow structure photothermal evaporation device is 10-30 wt%.

[0022] The present invention also provides a method for preparing the honeycomb hollow structure photothermal evaporation device, comprising the following steps: 1) Preparation of the aforementioned spherical flower photothermal evaporation material; 2) Dissolve PVA powder in deionized water and heat at 80-90℃ until completely dissolved to form a PVA aqueous solution with a mass concentration of 5%-10%; dissolve PAM powder in deionized water and stir at room temperature until completely dissolved to form a PAM aqueous solution with a mass concentration of 0.5%-1%; mix the two aqueous solutions and stir evenly, add the sphere-borne photothermal evaporation material, stir for 30-60 minutes until uniformly dispersed, add glutaraldehyde crosslinking agent, the amount of which is 1%-5% of the total mass of PVA and PAM, and simultaneously add hydrochloric acid dropwise to adjust the pH of the system to 3.0-4.0, and continue stirring for 5-10 minutes to form a stable mixed slurry; 3) Quickly inject the mixed slurry into the molds of the T-shaped evaporator body and the cylindrical covering part. After the slurry solidifies, move the mold to a -25°C freezer for 12-24 hours, and then move it to a -40 to -50°C freeze dryer for 36-48 hours. Demold to obtain each evaporator component. 4) Assemble the T-shaped evaporator body, the cylindrical covering and the base, pass the end of the vertical water supply column of the evaporator component through the cylindrical covering and insert it into the base to obtain the honeycomb hollow structure photothermal evaporation device.

[0023] A mold can be prepared by 3D printing to match the integrated structure of the T-shaped evaporation body and the outer cylindrical coating (the material is polylactic acid or photosensitive resin, and the printing accuracy is ±0.1mm).

[0024] Compared with the prior art, the present invention has the following significant advantages: 1) Photothermal material innovation: Through the "carbon sphere core – MoS2 flower shell" structure, multiple scattering and broadband absorption of light are achieved, significantly improving the photothermal conversion efficiency; 2) Thermal management optimization: PVA-PAM composite aerogel provides low thermal conductivity channels, enabling uniform heat distribution inside the device and reducing external heat loss; 3) Structural-functional coupling: The honeycomb disc and the hollow cavity form a double-layer evaporation system of "external direct evaporation + internal convection evaporation", making full use of absorbed heat energy; 4) Anti-salinization design: The T-shaped water supply path realizes the water flow from bottom to top and outward, continuously flushing salt to the edge of the disc and preventing salt blockage and accumulation; 5) Excellent overall performance: The evaporation rate is significantly improved under 1 sun conditions, and the stable performance is maintained during long-term seawater desalination.

[0025] In summary, this invention constructs a solar evaporation system that integrates light absorption, thermal management, and anti-salt crystallization through the synergistic design of spherical photothermal materials and honeycomb hollow structures. It has the advantages of high efficiency, sustainability, and structural stability, and can be widely used in seawater desalination, brackish water desalination, and other fields. Attached Figure Description

[0026] Figure 1 The images shown are SEM and EDS images of materials at different stages in Example 1.

[0027] Figure 2 The images show actual pictures and corresponding model diagrams of evaporators with different structures.

[0028] Figure 3 The variation of unit area mass of evaporators with different structures under 1 sun conditions.

[0029] Figure 4 Evaporation rates of honeycomb hollow structure photothermal evaporation devices of different heights under 1 sun conditions.

[0030] Figure 5 Figure 1 shows the water absorption test results for photothermal evaporation devices with different honeycomb hollow structures.

[0031] Figure 6 The image shows the salt resistance of the honeycomb hollow structure photothermal evaporation device in Example 1 and its comparison with that of a traditional solid structure photothermal evaporation device.

[0032] Figure 7This is a comparison chart showing the evaporation rates of the honeycomb hollow structure photothermal evaporation device of Example 1 and the traditional solid structure photothermal evaporation device for evaporating 20% ​​NaCl.

[0033] Figure 8 This diagram illustrates the heat transfer and water transport during operation of a honeycomb hollow structure photothermal evaporation device and a traditional solid structure photothermal evaporation device.

[0034] Figure 9 The UV-Vis-NIR absorption spectrum of the photothermal evaporation material (C@MoS2) on spheres in the wavelength range of 200–2500 nm is shown.

[0035] Figure 10 This is a schematic diagram of the working principle of a honeycomb hollow structure photothermal evaporation device. Detailed Implementation

[0036] The principles and features of the present invention are described below. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0037] Unless otherwise specified, the test methods used in the embodiments are conventional methods; unless otherwise specified, the materials and reagents used are commercially available.

[0038] Example 1 1. Preparation of photothermal evaporation materials for spherical flowers 1) Dissolve glucose in deionized water to prepare a solution with a mass concentration of 0.1 mol / L, transfer it to a high-pressure reactor, and hydrothermally react at 180 ℃ for 10 h at a pressure of about 7.5 MPa. After the reaction, centrifuge, wash and vacuum dry at 70 ℃ for 5 h to obtain spherical carbon spheres with an average particle size of about 6–8 μm.

[0039] 2) The above-mentioned carbon spheres were dispersed in a mixed aqueous solution containing ammonium molybdate and thiourea (molar ratio of 1:40, carbon sphere concentration of 7 g / L). After ultrasonic dispersion, the mixture was transferred to a reaction vessel and subjected to hydrothermal reaction at 200 °C for 18 h at a pressure of approximately 11 MPa. After cooling, the product was centrifuged, washed, and dried to obtain a C@MoS2 photothermal composite material with three-dimensional flower-like MoS2 nanosheets of approximately 200–300 nm uniformly grown on its surface.

[0040] 2. Preparation of composite aerogel solution Weigh out polyvinyl alcohol (PVA) powder and dissolve it in deionized water. Stir at 85 °C until completely dissolved to form an 8 wt% solution. Separately, dissolve polyacrylamide (PAM) powder in deionized water and stir until a 1 wt% solution is formed. Mix PVA:PAM at a mass ratio of 5:0.5 and stir. Add the above-mentioned spherical photothermal material (20 wt% of the total mass) and continue stirring for 45 min until uniformly dispersed. Then add glutaraldehyde crosslinking agent (3 wt% of the total mass) and adjust the pH to 3.5 with dilute hydrochloric acid to obtain a stable composite slurry.

[0041] 3. Preparing device molding die A mold was prepared by 3D printing to match the integrated structure of the T-shaped evaporator body and the outer cylindrical covering. The honeycomb disc layer has a diameter of 3 mm and a quantity of 6 holes. The hollow cavity has an inner diameter of 15 mm and an outer diameter of 24 mm. The T-shaped column has a height of 40 mm.

[0042] 4. Molding and Drying The composite slurry was injected into the mold, allowed to stand, and then frozen in a -25 ℃ refrigerator for 18 h. After freezing and drying at -45 ℃ for 40 h, the mold was removed to obtain a photothermal evaporation component with an overall honeycomb hollow structure.

[0043] 5. Assembly and Performance Testing The lower end of the vertical water supply column of the evaporation component is inserted into the polystyrene foam base for fixation, forming a honeycomb-shaped hollow structure photothermal evaporation device. (1 sun (1 kW·m)) -2 An evaporation experiment was conducted under simulated sunlight conditions. The results showed: Pure water evaporation rate: 3.11 kg·m -2 ·h -1 Evaporation rate of Bohai Sea: 2.85 kg·m -2 ·h -1 Evaporation rate of 20 wt% NaCl solution: 1.61 kg·m -2 ·h -1 During long-term operation, no obvious salt formation was observed on the evaporation surface, proving that the structure has excellent anti-salt crystallization and stable thermal management performance.

[0044] like Figure 1 As shown, scanning electron microscopy (SEM) fully reveals the core structure and component characteristics of this invention: Figure 1In section a, carbon spheres (C) have a spherical core with uniform particle size and regular morphology, providing a stable substrate for subsequent functional layer loading. The uniformly coated molybdenum disulfide nanoflowers on their surface form a unique "flower on sphere" structure (C@MoS2). This structure significantly improves light-harvesting ability and interfacial hydrophilicity through the multi-level morphology of the nanoflowers. Element mapping further verifies that Mo, S, and C are uniformly distributed in the material, ensuring the high efficiency and stability of photothermal conversion. Figure 1 b shows the porous network structure of PVA-PAM composite aerogel. This interconnected porous morphology not only endows the matrix with good low thermal conductivity, which can effectively inhibit heat loss to water, but also creates channels for rapid water transport and timely salt removal. Figure 1 c presents the final honeycomb hollow structure photothermal evaporation device. The C@MoS2 photothermal material is uniformly dispersed in the PVA-PAM composite aerogel matrix. The uniformity of element distribution directly proves the efficient composite of the material and the matrix. This integrated structure of "photothermal material-porous matrix" not only gives full play to the wide-spectrum and efficient photothermal conversion performance of the C@MoS2 material, but also takes advantage of the porous and low thermal conductivity of the PVA-PAM composite aerogel. At the same time, the honeycomb hollow structure expands the evaporation area and optimizes the heat distribution. The three work together to lay a solid structural foundation for the efficient solar-driven seawater desalination.

[0045] like Figure 2As shown, the structural differences between the device of this invention and other types of devices are intuitively demonstrated through the comparison between the physical object and the model diagram: a) is CMPP HSE (the honeycomb hollow structure photothermal evaporation device of this invention), with a black surface and regular honeycomb-shaped through holes, and a hollow cavity inside. Heat can be transferred to the internal cavity through thermal convection and radiation, making the cavity wall also an evaporation surface, greatly expanding the evaporation area, and facilitating the efficient removal of salt; b) PP HSE (pure PVA-PAM composite aerogel device), which is light-colored and does not have photothermal conversion capability due to the lack of effective photothermal material; c) CMPP HSE (nh) (CMPP device without honeycomb holes at the top), which has no regular through holes at the top, but has a hollow cavity inside. Due to the lack of honeycomb holes at the top, the efficiency of heat transfer to the internal cavity and the effect of expanding the evaporation area are significantly weaker than a; d) Traditional 3D SSE (nh) (a traditional photothermal device without honeycomb holes) is a solid cylinder with no internal cavity. Heat can only be applied to the surface, resulting in limited evaporation area and easy loss to water and the external environment. e is a Traditional 3D SSE (a traditional photothermal device). Although it has regular holes on the surface, it lacks an internal hollow cavity. Heat cannot be transferred to the interior through thermal convection and radiation to form an additional evaporation surface. Its structural design is far inferior to the honeycomb hollow structure of this invention in terms of evaporation area expansion and heat utilization. The model diagram of fj below further clearly shows the structural differences of each device, highlighting the innovation of the CMPP HSE in the "honeycomb through-hole + internal hollow cavity" structural design. This structure uses thermal convection and radiation to transfer heat to the cavity wall, forming multi-interface evaporation. It works synergistically with the on-spherical photothermal material and PVA-PAM composite aerogel to provide structural support for efficient photothermal evaporation. At the same time, through comparison with other types of devices, the significant advantages of this invention in structural optimization are intuitively demonstrated.

[0046] like Figure 3 As shown, the photothermal evaporation performance of different devices under 1 sun is visually compared through mass change curves: in the left side, the evaporation rate of the CMPP HSE of this invention reaches 3.11 kgm³. -2 h -1 It was significantly higher than PP-HSE (0.79 kgm). -2 h -1 ) and CMPPHSE (nh) (2.07 kgm -2 h -1 ),; on the right, CMPP HSE also outperforms the traditional 3D SSE (nh) (2.38 kgm) of conventional devices. -2 h -1 ) and Traditional 3D SSE (2.57 kgm -2 h -1The data fully demonstrate that the "spherical flower photothermal material + honeycomb hollow structure" system of this invention achieves a significant increase in water evaporation rate and exhibits excellent photothermal evaporation performance.

[0047] like Figure 4 The bar chart shown illustrates the relationship between the evaporation rate and the height of the honeycomb hollow structure photothermal evaporation device of this invention, used to clarify the influence of device height on evaporation performance: When the device height is 2 cm, the evaporation rate is 2.83 kgm³. -2 h -1 ; When the height increases to 3 cm, the evaporation rate increases to 2.96 kgm³. -2 h -1 ; At a height of 4 cm, the evaporation rate reaches its peak of 3.11 kg / m³. -2 h -1 ; When the height is further increased to 5 cm, the evaporation rate drops to 3.03 kg / m³. -2 h -1 .

[0048] The results indicate that the height of the honeycomb hollow structure photothermal evaporation device of this invention is positively correlated with the evaporation rate within a certain range, with 4 cm being the optimal height. Beyond this height, the evaporation rate decreases slightly. This conclusion provides experimental support for the height optimization design of the device of this invention and can guide the selection of a height of 4 cm to achieve the highest photothermal evaporation efficiency in practical applications.

[0049] like Figure 5 As shown, the advantages of the device of the present invention in terms of hydrophilicity and water transport performance are clearly demonstrated: Figure 5 In sample a, the contact angle of CMPP HSE (T-type evaporation substrate containing PAM) was only 20° at 0.15s, while that of CMP HSE (control sample without PAM) was 39° at the same time. Moreover, the water droplets of CMPP HSE could spread rapidly at 0.24s, indicating that the hydrophilicity was significantly improved after the addition of PAM. Figure 5 In step b, the moisture in the T-shaped evaporator rises rapidly along the structure and diffuses evenly outwards after reaching the top disk, while the moisture transport in the outer cylindrical covering is slow and unevenly dispersed. This clearly demonstrates the advantage of the T-shaped structure in terms of moisture transport speed. These results fully prove that this invention, through the T-shaped structure design and the introduction of PAM, achieves a synergistic improvement in hydrophilicity and moisture transport efficiency, providing strong support for efficient photothermal evaporation.

[0050] like Figure 6 As shown, the system demonstrates the salt resistance of the honeycomb hollow structure photothermal evaporation device of the present invention: Figure 6a represents the device's ability to dissolve and remove 0.5g of NaCl in the dark; the salt content gradually decreases over time, and there is almost no residue after 60 minutes. Figure 6 b and Figure 6 c represents the evaporation experiment of 20 wt% NaCl under 1 sun illumination. The device of this invention ( Figure 6 b) After 8 hours, there was less surface salt accumulation, and the salt was mainly concentrated at the edge of the top disk, while traditional devices ( Figure 6 c) Excessive salt accumulation on the surface, even leading to salt blockage. These results demonstrate that the device of the present invention exhibits excellent salt resistance stability under both light and dark environments, and can efficiently process high-concentration salt solutions, thus overcoming the technical bottleneck of salt blockage in traditional photothermal evaporation devices.

[0051] like Figure 7 As shown, the long-term evaporation stability of the CMPP HSE of this invention was compared with that of Traditional 3D SSE (nh): Under experimental conditions of 20 wt% NaCl solution and 1 sun illumination, the evaporation rate of CMPP HSE remained at 1.5 kgm³ for 8 hours. -2 h -1 The above results show a small attenuation rate, and no obvious salt blockage on the surface after 8 hours; while the evaporation rate of Traditional 3D SSE(nh) decreases significantly over time, reaching only about 0.3 kgm³ after 8 hours. -2 h -1 Furthermore, a large amount of salt accumulates on the surface. This fully demonstrates that the honeycomb hollow structure photothermal evaporation device of this invention has excellent long-term working stability in a high-salt environment, can maintain high efficiency during continuous photothermal evaporation, and solves the problem of performance degradation of traditional devices due to salt blockage.

[0052] like Figure 8 The diagram illustrates the mechanism of thermal management and moisture transport, clearly demonstrating the performance advantages of the device of this invention: The left side shows the honeycomb hollow structure photothermal evaporation device of this invention. After solar energy input, thermal management is achieved through radiation, convection, and conduction. The temperature of the central cavity rises, making the inner wall an evaporation surface. Simultaneously, moisture diffuses to the sides along the blue path, flushing the salt accumulated at the top to the edge of the top evaporation surface, preventing salt accumulation on the device surface. The right side shows a traditional device, where only the surface can serve as an evaporation surface, resulting in low moisture transport efficiency and no salt flushing mechanism. This diagram visually reveals that the device of this invention achieves efficient solar energy utilization, rapid moisture evaporation, and excellent salt resistance through the synergistic effect of "honeycomb hollow structure (inner wall as evaporation surface + moisture diffusion to the edge to flush salt) + efficient thermal management," while traditional devices have significant shortcomings in these aspects.

[0053] like Figure 9As shown, the UV-Vis-NIR broadband absorption properties of carbon spheres (C) and molybdenum disulfide-modified carbon spheres (C@MoS2) in the wavelength range of 200–2500 nm are presented, along with the energy density distribution (right axis) of the AM 1.5G (1 sun) standard solar spectrum within the same wavelength band. The results indicate that both materials can achieve continuous absorption across the UV, visible, and near-infrared regions. C@MoS2 exhibits further enhanced absorption across the entire wavelength range, and shows a higher degree of matching with the AM 1.5G spectrum in the visible-near-infrared region, where solar irradiance energy is mainly concentrated. This broadband and strong absorption characteristic provides a material basis for subsequent realization of efficient photothermal conversion, interfacial thermal localization, and continuous and stable evaporation.

[0054] like Figure 10 The diagram shown is a schematic diagram of the working principle of a honeycomb hollow structure photothermal evaporation device.

[0055] Comparative Example 1 Performance comparison of evaporators with different heights To verify the effect of evaporator height on the evaporation performance of the honeycomb hollow structure photothermal evaporation device of the present invention, a series of samples were prepared according to the material formulation and preparation method of Example 1, with only the total height of the evaporation assembly changed while keeping other process parameters constant. The heights of the obtained samples were 2 cm, 3 cm, 4 cm, and 5 cm, respectively.

[0056] At 1 sun (1 kW·m -2 The evaporation test results under sunlight irradiation conditions are as follows: when the device height is 2 cm, the evaporation rate is 2.83 kg·m³. -2 ·h -1 At a height of 3 cm, the evaporation rate is 2.96 kg·m³. -2 ·h -1 At a height of 4 cm, the evaporation rate reaches its peak of 3.11 kg·m³. -2 ·h -1 At a height of 5 cm, the evaporation rate drops to 3.03 kg·m³. -2 ·h -1 Therefore, it can be seen that the evaporator height is positively correlated with the evaporation rate within a certain range, and 4 cm is the optimal height for this system. Beyond this height, the evaporation rate decreases slightly (see...). Figure 4 The comparative results demonstrate that the device height is a crucial structural parameter affecting the convection intensity and heat-fluid coupling within the cavity. Appropriately increasing the height facilitates more efficient cavity convection and heat recirculation, thereby enhancing the evaporation rate; however, when the height exceeds a certain range, it may lead to changes in the convection pattern or a decrease in water / steam discharge efficiency, causing the evaporation rate to decline. Therefore, this invention preferentially uses 4 cm as the evaporation component height to achieve optimal photothermal evaporation efficiency.

[0057] Comparative Example 2 Evaporation unit without added photothermal materials (PP HSE) To verify the role of photothermal materials in evaporation performance, a sample was prepared according to the method in Example 1, but without adding the spherical photothermal evaporation material; only PVA-PAM composite aerogel was used as the main structural material, with the remaining steps and conditions remaining the same. The resulting sample was designated PP HSE.

[0058] At 1 sun (1 kW·m -2 Under sunlight, the evaporation rate of pure water is 0.79 kg·m³. -2 ·h -1 This is significantly lower than that of the device of the present invention (3.11 kg·m). -2 ·h -1 The results show that the light absorption and photothermal conversion capabilities of the device are significantly reduced when no photothermal component is introduced, indicating that the composite of photothermal materials plays a key role in the overall evaporation efficiency.

[0059] Comparative Example 3 Evaporation apparatus without honeycomb structure (CMPP HSE (nh)) The material was prepared according to the formulation of Example 1, but the honeycomb structure on the surface of the disc evaporation layer was removed, and only the flat evaporation interface was retained. The remaining steps and parameters were the same. The resulting sample was denoted as CMPP HSE (nh).

[0060] Under the same conditions, its pure water evaporation rate was 2.67 kg·m³. -2 ·h -1 Compared to Example 1, the evaporation rate decreased by approximately 14%. This result indicates that the honeycomb pore structure can significantly enhance surface airflow and vapor diffusion, facilitating the formation of multi-interface evaporation paths and increasing the evaporation rate.

[0061] Comparative Example 4 Traditional solid cylindrical evaporation device (Traditional 3D SSE (nh)) Prepared according to the material formulation of Example 1, but without an external cylindrical covering, only a solid cylindrical evaporator with no honeycomb pores on the surface and no internal cavity. The resulting sample is designated as Traditional 3D SSE (nh).

[0062] Under the same conditions, the evaporation rate of pure water was 2.28 kg·m⁻². -2 ·h -1 The heat loss is approximately 27% compared to the present invention. This result demonstrates that the hollow cavity structure can form a thermal convection and secondary evaporation interface inside, thereby improving heat utilization and reducing surface heat loss.

[0063] Comparative Example 5 Traditional solid cylindrical evaporator with honeycomb structure (Traditional 3D SSE) The material system of Example 1 was used for preparation, but without an external cylindrical covering; instead, a solid cylindrical evaporator with honeycomb-like pores on the surface and no internal cavity was used. The resulting sample was designated Traditional 3D SSE.

[0064] Under the same conditions, the pure water evaporation rate was measured to be 2.57 kg·m³. -2 ·h -1 Compared to Example 1, the performance decreased by approximately 17%, indicating that although the device with only surface pores can partially enhance convection, the heat is still concentrated on the surface, making it difficult to form an efficient heat reuse process.

[0065] Comparative Example 6 PAM-free evaporation unit (CMP HSE) To verify the role of PAM in the composite aerogel matrix, it was prepared according to the method of Example 1, but without the addition of polyacrylamide (PAM), using only PVA as the matrix, while keeping the other raw material ratios and process conditions consistent. The resulting sample was named CMP HSE.

[0066] Surface wettability tests were performed on the CMP-HSE and Example 1 (CMPP HSE) samples (see...). Figure 5 Test results showed that at 0.15 s, the contact angle of CMPP HSE was approximately 20°, while that of CMP HSE was approximately 39°; and the water droplets of CMPP HSE spread rapidly within 0.24 s. These results indicate that the introduction of PAM significantly improved the hydrophilicity of the composite aerogel, forming a more complete capillary water supply network, promoting rapid spreading and uniform distribution of water, which is beneficial for continuous water supply and heat utilization at the evaporation interface, thereby improving evaporation stability and operational reliability.

[0067] Example 2 The photothermal evaporation material (C@MoS2) with flowers on spheres obtained in Example 1 was subjected to ultraviolet-visible-near-infrared absorption spectroscopy (200–2500 nm). The results showed that the average absorptivity of the material in the 200–2500 nm range was approximately 92.6%; the average absorptivity in the 400–2500 nm range, where solar energy is mainly distributed, was approximately 93.0%, and the absorptivity remained stable at approximately 90.0%–97.3%. In contrast, the average absorptivity of a single carbon sphere (C) in the 400–2500 nm range was approximately 85.8%. Therefore, the broadband absorption performance of the photothermal evaporation material with flowers on spheres was significantly higher than that of a single carbon sphere (an improvement of approximately 7.2 percentage points).

[0068] In other embodiments, the parameters can be adjusted within a defined range.

[0069] In summary, this invention proposes a honeycomb hollow structure solar evaporation device based on a spherical flower-shaped photothermal composite material. A T-shaped evaporation system is constructed using a spherical flower-shaped photothermal composite material and a PVA-PAM composite aerogel. Through the structural design of the honeycomb pores and hollow cavities, multi-interface evaporation and internal heat convection reuse are achieved, effectively improving photothermal conversion and energy utilization efficiency. The introduction of PAM into the composite matrix enhances the material's hydrophilicity, ensuring a continuous and stable water supply; the T-shaped water supply path promotes salt diffusion from the center outwards, significantly inhibiting surface salt deposition. Under different light conditions and salt concentrations, the device maintains a high evaporation rate and excellent long-term operational stability. This invention has a reasonable structural design and a simple preparation process, and can be widely applied in solar-driven water evaporation, seawater desalination, and brackish water purification.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A spherical photothermal evaporation material, characterized in that: Includes carbon spheres, the surface of which is coated with a specific surface area greater than 20 m². 2 / g molybdenum disulfide nanoflower layer.

2. The spherical flower photothermal evaporation material according to claim 1, characterized in that: The carbon spheres have a spherical structure; The molybdenum disulfide nanoflower layer is a nanoflower structure with a size of 200-300 nm formed from dense molybdenum disulfide nanosheets; The specific surface area of ​​the molybdenum disulfide nanoflower layer is 20-80 m² / g.

3. The spherical flower photothermal evaporation material according to claim 1, characterized in that: The mass ratio of the molybdenum disulfide nanoflower layer to the carbon sphere is 1.0-1.5:1.

0.

4. A method for preparing the spherical flower photothermal evaporation material according to any one of claims 1 to 3, characterized in that, Includes the following steps: 1) Preparation of carbon spheres: Glucose was dissolved in deionized water to form an aqueous solution with a concentration of 0.1-0.2 mol / L. Then, a hydrothermal reaction was carried out in a high-pressure reactor at 160-180℃ for 8-12 hours at a pressure of 4-8 MPa. After the reaction, the mixture was centrifuged, washed, and vacuum dried at 60-80℃ for 4-6 hours to obtain carbon spheres with a size of 6-8 μm. 2) Preparation of carbon spheres coated with molybdenum disulfide nanoflowers: Carbon spheres were dispersed in a mixed aqueous solution of ammonium molybdate and thiourea. After ultrasonic dispersion, the mixture was subjected to a hydrothermal reaction at 180-220℃ for 12-24 hours under a pressure of 7-15 MPa in a high-pressure reactor. After the reaction, the mixture was centrifuged, washed, and vacuum dried at 60-80℃ for 6-8 hours to obtain carbon spheres coated with molybdenum disulfide nanoflowers. The molar ratio of carbon spheres, ammonium molybdate, and thiourea was (60-100):1:(30-50), and the carbon sphere dispersion concentration was 6-8 g / L.

5. A photothermal evaporation material, characterized in that, The material is prepared by the following method: A composite gel liquid is prepared by combining the *Planctomyces globosum* photothermal evaporation material according to any one of claims 1 to 3, PVA, PAM, and an appropriate amount of crosslinking agent. The gel is then cast, freeze-dried, and a honeycomb aerogel with through-pores is formed, thus obtaining the photothermal evaporation material. The mass ratio of the *Planctomyces globosum* photothermal evaporation material, PVA, and PAM is (0.25-0.5):5:(0.25-1); the amount of crosslinking agent added is 1%-5% of the total mass of PVA and PAM.

6. A honeycomb hollow structure photothermal evaporation device, characterized in that, include: Base; And an evaporation assembly fixed on the base, the evaporation assembly comprising an inner T-shaped evaporation body and an outer cylindrical covering, wherein the material of the T-shaped evaporation body and / or the cylindrical covering is selected from the photothermal evaporation material of claim 5.

7. The honeycomb hollow structure photothermal evaporation device according to claim 6, characterized in that: The T-shaped evaporator body includes an upper disc evaporation layer and a lower vertical water supply column; A hollow cavity is formed between the cylindrical covering and the vertical water supply column, and the sidewall of the hollow cavity constitutes the inner wall evaporation interface; The end of the vertical water supply column away from the evaporation layer of the disc is fixed to the base, and the vertical water supply column and the base form a T-shaped water supply and salt discharge channel.

8. The honeycomb hollow structure photothermal evaporation device according to claim 7, characterized in that: In the disc evaporation layer, the thickness of the disc is 5-10mm, and the disc is provided with several through holes. The diameter of the through holes is 2-5mm, the distance between the through holes and the center of the disc is 10-15mm, and the number of through holes is 4-8. The inner diameter of the hollow cavity is 14-16mm, the outer diameter of the hollow cavity is 20-30mm, and the wall thickness of the cylindrical covering is 6-10mm.

9. The honeycomb hollow structure photothermal evaporation device according to claim 7, characterized in that: The base is made of polystyrene foam; The vertical water supply column is inserted into the base to a depth of 0.3-1cm; The mass percentage of the spherical flower photothermal evaporation material in the honeycomb hollow structure photothermal evaporation device is 10-30 wt%.

10. A method for preparing a honeycomb hollow structure photothermal evaporation device according to any one of claims 6 to 9, characterized in that, Includes the following steps: 1) Preparation of photothermal evaporation materials with spherical flowers; 2) Dissolve PVA powder in deionized water and heat at 80-90℃ until completely dissolved to form a PVA aqueous solution with a mass concentration of 5%-10%; dissolve PAM powder in deionized water and stir at room temperature until completely dissolved to form a PAM aqueous solution with a mass concentration of 0.5%-1%; mix the two aqueous solutions and stir evenly, add the sphere-based photothermal evaporation material, stir for 30-60 minutes until uniformly dispersed, add glutaraldehyde crosslinking agent, the amount of which is 1%-5% of the total mass of PVA and PAM, and simultaneously add hydrochloric acid to adjust the pH of the system to 3.0-4.0, continue stirring for 5-10 minutes to form a stable mixed slurry, wherein the mass ratio of the sphere-based photothermal evaporation material, PVA and PAM is (0.25-0.5):5:(0.25-1); 3) Quickly inject the mixed slurry into the molds of the T-shaped evaporator body and the cylindrical covering part. After the slurry solidifies, move the mold to a -25°C freezer for 12-24 hours, and then move it to a -40 to -50°C freeze dryer for 36-48 hours. Demold to obtain each evaporator component. 4) Assemble the T-shaped evaporator body, the cylindrical covering and the base, pass the end of the vertical water supply column of the evaporator component through the cylindrical covering and insert it into the base to obtain the honeycomb hollow structure photothermal evaporation device.

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