Integrated preparation method for controllable wetting corrosion-resistant bionic water collecting surface induced by femtosecond laser

Abstract

The invention discloses a femtosecond laser induced controllable wetting corrosion-resistant bionic water collecting surface integrated preparation method, and belongs to the technical field of surface functional materials. According to the method, accurate regulation and control of infrared emissivity, continuous regulation of hydrophilic and hydrophobic performance and corrosion resistance enhancement are synchronously realized on the same base material, and the limitation of single-function modification is broken through; according to the method, the limitation of a multi-step surface modification process is overcome, the structure and performance change is realized only through laser parameter regulation and control in one step, and the preparation efficiency is improved. According to the manufactured bionic water collection panel, automatic flow guiding and efficient collection of liquid are achieved through the wettability gradient, water collection is collaboratively optimized through the difference of infrared emissivity, and usability and corrosion resistance are both considered. In practical application, zero-energy-consumption continuous water collection is achieved without extra power, and the device has wide application prospects in the field of air water collection.

Description

Technical Field

[0001] The present invention relates to the technical field of surface functionalized materials, and in particular to an integrated preparation method of a femtosecond laser-induced controllable wetting and corrosion-resistant bionic water-collecting surface. Background Art

[0002] Existing biomimetic water-harvesting surfaces utilize methods such as chemical modification, 3D printing, and coating technologies to mimic the contrasting superhydrophobic and superhydrophilic regions found on certain biological surfaces or structures in nature to drive directional transport of droplets, thereby efficiently collecting water from the air. However, these surfaces present several significant challenges. First, metal substrates are susceptible to oxidation when exposed to humid or corrosive environments, resulting in degradation of their designed wetting properties, affecting water-harvesting efficiency and service life. Second, achieving the desired combination of superhydrophobic and superhydrophilic properties typically requires multiple chemical modification steps (such as stearic acid modification), which not only increases manufacturing costs but also can lead to reduced yield and inefficient production. Furthermore, conventional biomimetic water-harvesting surfaces struggle to simultaneously achieve both efficient water collection and corrosion resistance, limiting their application scope due to their limited functionality. Surfaces that rely on chemical coatings to achieve superhydrophobicity are particularly vulnerable to corrosive environments such as seawater, as these coatings can fail due to flaking or decomposition, and can be penetrated by aggressive ions, leading to performance degradation. In practice, additional protective measures may be required to enhance corrosion resistance, further increasing system complexity and cost.

[0003] Chinese invention patent publication number CN115008018A discloses a method for preparing durable superhydrophobic surfaces using femtosecond laser composite rare earth nanostructured materials. The method includes experimental pretreatment, femtosecond laser-based surface texturing, mechanical durability enhancement and preliminary modification of intrinsic hydrophobicity through nanostructured rare earth metal oxides, and modulation of superhydrophobic extreme wetting properties under temperature-controlled aging. This method utilizes a femtosecond laser to complete texturing, combining the biomimetic design of the structure with the intrinsic hydrophobicity, chemical stability, and strong wear resistance of rare earth metal oxides to achieve excellent mechanical durability. However, the process is complex, requiring a step-by-step process for surface texturing and nanostructured rare earth metal oxides. Furthermore, the high cost of rare earth metal oxides limits the applicability of the raw materials.

[0004] The Chinese invention patent with publication number CN109877472A provides a method for preparing a super-hydrophilic-super-hydrophobic composite SERS substrate based on femtosecond laser. This method uses femtosecond laser selective deposition to achieve the combination of a super-hydrophobic surface and a hydrophilic substrate, and then uses laser direct writing to selectively process super-hydrophilic areas to achieve the preparation of a patterned super-hydrophilic-super-hydrophobic interlaced surface. This invention method only requires a femtosecond laser and does not require sample movement, and is applicable to any intrinsically hydrophilic substrate. However, its preparation relies on a dual hydrophilic and hydrophobic substrate, and the raw materials include gold nanoparticles, which makes the modification strategy complex and costly.

[0005] Ultrafast laser micro-nano processing can simultaneously achieve micro-nano structure construction and surface chemical property regulation through the nonlinear interaction of pulsed laser and material. On the one hand, the wetting behavior can be dynamically controlled by precisely designing the surface morphology, and the integration of super-hydrophobic / hydrophilic water areas can be achieved without chemical modification. Secondly, the laser-induced micro-nano structure itself forms a physical anti-corrosion barrier, significantly improving the intrinsic corrosion resistance of the substrate. Finally, due to its cold processing characteristics, the formation of heat-affected zones is avoided, ensuring processing accuracy and structural integrity. However, this technology is highly sensitive to material-parameter matching. For example, the super-hydrophobic surface of silicone rubber requires strict optimization of laser power and scanning strategy, otherwise it is easy to induce microscopic defects and lead to functional failure.

[0006] In summary, a bionic water-collecting surface integrated preparation method was designed to simultaneously achieve precise control of infrared emissivity, continuous adjustment of hydrophilic and hydrophobic properties, and enhanced corrosion resistance on the same substrate; and overcome the limitations of multi-step surface modification processes, achieving structural and performance changes in just one step through laser parameter control; this is of great significance for breaking through the limitations of single-function modification and improving process efficiency. Summary of the Invention

[0007] In view of the above-mentioned defects of the prior art, in a first aspect of the present invention, a method for preparing an integrated bionic water-collecting surface with controllable wetting and corrosion resistance induced by femtosecond laser is provided, comprising the following steps: Femtosecond laser processing: Remove impurities from the surface of the iron substrate; then, in an air environment, use femtosecond laser to irradiate the surface of the iron substrate and adjust the repetition frequency to self-deposit Fe@FeO x The core-shell structure forms a super-hydrophobic droplet capture layer, a super-hydrophilic droplet transport layer, and a droplet collection layer on the surface of the iron substrate; Bionic water collection panel structure design: A bionic gradient pattern is fabricated on the surface of an iron substrate, including a super-hydrophobic network channel formed by a droplet capture layer, a super-hydrophilic triangular main channel and a network of linear channels formed by a droplet transport layer, and a water storage area formed by a droplet collection layer; Get the bionic water collection panel.

[0008] Preferably, in the femtosecond laser processing, after the surface of the iron substrate is polished to a mirror surface, ultrasonic cleaning is performed with acetone, ethanol, and deionized water in sequence to remove impurities on the surface of the iron substrate, and the substrate is dried for later use.

[0009] Preferably, in the femtosecond laser processing, the wavelength of the femtosecond laser is 515 nm, the pulse is 250 fs, and the energy density is 6×10 3 GW / cm 2 , the pulse frequency is 10~80 kHz.

[0010] Further preferably, the wettability and infrared emissivity of the iron substrate surface are adjusted by controlling the pulse frequency; when the pulse frequency increases, the Fe@FeO x As the size of the core-shell structure decreases, the wettability gradually changes from superhydrophobic to superhydrophilic, and the infrared emissivity decreases accordingly.

[0011] Furthermore, when the surface of the iron substrate is superhydrophobic, the water contact angle is greater than 150° and the infrared emissivity is greater than 0.95; when it is superhydrophilic, the water contact angle is less than 20° and the infrared emissivity is less than 0.03.

[0012] Preferably, in the bionic water collection panel structure design, the spacing of the super-hydrophobic mesh channels is 0.1~1 mm, the angle between the oblique hydrophobic channels and the transverse parallel hydrophobic channels is 15°~90°; the top angle of the super-hydrophilic triangular main channel is 5°~60°; the water storage area is a circular super-hydrophilic area with a diameter of 2~5 mm.

[0013] The surface's super-hydrophobic mesh channels capture tiny droplets in the atmosphere. Under the control of the above-mentioned spacing and angle parameters, the probability of droplet collisions can be increased, and nighttime radiation cooling can be achieved, promoting the generation of condensed water. As a result, droplets roll into the super-hydrophilic triangular main channel under the action of temperature gradient, gravity, and surface tension. Together with the meshed linear channels, the droplets are driven to converge in a directional manner into the circular water storage area. Among them, the triangular main channel provides the Laplace pressure differential driving force, and the meshed auxiliary channel expands the water collection area, and the water collection efficiency is improved compared to traditional surfaces.

[0014] In a second aspect of the present invention, a bionic water collection panel with high water collection efficiency is provided, which is manufactured using the method provided in the first aspect of the present invention.

[0015] In a third aspect of the present invention, there is provided an application of the bionic water collection panel according to the second aspect of the present invention for collecting water in the air.

[0016] Preferably, the application includes combining a bionic water collection panel, a water guide device, and a water storage device; the water collected by the bionic water collection panel slides to the water storage device through the water guide device, achieving zero-energy consumption, evaporation-proof continuous water collection.

[0017] Further preferably, the inclination angle between the bionic water collection panel and the water guide device is 5°~30°; no additional power is required, and gravity is used to make the gathered droplets slide naturally to the water storage device.

[0018] Based on the above technical solutions, the design concept and principle of the present invention are as follows: The present invention provides a method for preparing Fe@FeO based on femtosecond laser self-deposition technology. x The method of narrow distribution (high frequency) core-shell structure. Through integrated processing of single substrate, simplified materials and process flow, Fe@FeO x In situ construction of core-shell structures and multifunctional interface construction. By increasing the laser frequency, the core-shell size and surface chemistry are modulated, transforming the material surface from hydrophobic to hydrophilic. This method simultaneously achieves precise control of infrared emissivity, continuous adjustment of hydrophilic and hydrophobic properties, and enhanced corrosion resistance on the same substrate, breaking through the limitations of single-function modification. Furthermore, without the need for a multi-step surface modification process, structural and performance changes can be achieved in a single step through laser parameter manipulation, improving process efficiency.

[0019] During the preparation process, this process is designed to form molten droplets and nanoparticles on the surface of the iron-based material through the Coulomb explosion and phase explosion mechanism. These high-temperature particles are rapidly oxidized and self-deposited on the surface to form a metal core and FeO x The structure of the shell, and the high pulse frequency promotes the breakup of the molten droplets and the refinement of the oxide layer, while reducing the cooling time, resulting in a reduction in the size of the core-shell structure. The size of the core-shell structure decreases with the increase of the laser pulse frequency, and the infrared emissivity also decreases. When the size of the structure is large, it can excite magnetic resonances of different orders and concentrate specific bands, thereby achieving effective regulation of the infrared emissivity. In addition, the hydrophilic and hydrophobic properties of the surface can be continuously regulated by adjusting the laser frequency, and the dense FeO x The outer shell significantly improves the corrosion resistance of the material.

[0020] Based on this characteristic, the present invention controls the core-shell size through laser parameters. Larger core-shell structures exhibit superhydrophobic properties and high infrared emissivity, facilitating localized cooling and promoting condensation into droplets. Smaller core-shell structures, on the other hand, exhibit superhydrophilic properties and low infrared emissivity, helping to maintain high temperatures and thereby driving rapid droplet migration. This enables efficient management of droplets from capture to collection, achieving high water collection efficiency. Combining these mechanisms, a three-level structure consisting of a biomimetic water collection panel, a water guide, and a water storage device is constructed, enabling the capture, directional transport, and collection of droplets.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention provides an integrated preparation method for a controllable wetting and corrosion-resistant bionic water-collecting surface induced by a femtosecond laser, which simultaneously realizes precise control of infrared emissivity, continuous adjustment of hydrophilic and hydrophobic properties, and enhanced corrosion resistance on the same substrate, breaking through the limitations of single-function modification. This method overcomes the limitations of multi-step surface modification processes and achieves structural and performance changes in just one step through laser parameter control, thereby improving preparation efficiency.

[0022] The present invention provides a bionic water collection panel that utilizes a wettability gradient to achieve autonomous liquid flow and efficient collection, and synergistically optimizes water collection through differences in infrared emissivity, taking into account both usability and corrosion resistance.

[0023] The present invention provides an application of a bionic water collection panel, which can achieve zero-energy continuous water collection without the need for additional power, and has broad application prospects in the field of air water collection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 In the figure, (a) is a schematic diagram of femtosecond laser processing; (b) is the test results of pulse frequency and contact angle; (c) is the test results of pulse frequency and infrared emissivity; Figure 2 In the figure, (a) and (c) are the scanning electron microscope images and contact angle test results of the surface prepared under the preparation condition of 10 kHz pulse frequency, respectively; (b) and (d) are the scanning electron microscope images and contact angle test results of the surface prepared under the preparation condition of 80 kHz pulse frequency, respectively; Figure 3 Schematic diagram of the application of bionic water collection panel. DETAILED DESCRIPTION

[0025] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0026] Example 1 The integrated preparation method of a femtosecond laser-induced controllable wettability and corrosion-resistant biomimetic water-collecting surface comprises the following steps: Femtosecond laser processing: The size is 20×20×1 mm. 3 The commercial iron plate was mechanically polished to a mirror surface, and then ultrasonically cleaned with acetone, ethanol, and deionized water for 15 min each, and dried for later use. The femtosecond laser (wavelength 515 nm, pulse 250 fs, energy density 6×10 3 GW / cm 2 , pulse frequency 10~80kHz) in air environment to irradiate the surface, adjust the repetition frequency to self-deposit Fe@FeOx For core-shell structure, the higher the frequency, the smaller the size of the core-shell structure, and the wettability gradually changes from superhydrophobic to superhydrophilic; Bionic water collection panel structure design: Using a galvanometer scanning system to process bionic gradient patterns on the surface of iron-based materials; including: The super-hydrophobic mesh channels formed by the droplet capture layer capture tiny droplets in the atmosphere. The design parameters control the spacing between 0.1 and 1 mm and the angle between 15° and 90° to increase the probability of droplet collisions and achieve nighttime radiative cooling to promote condensation. The droplet transport layer forms a super-hydrophilic triangular main channel and a mesh-like linear channel. Droplets roll into the super-hydrophilic triangular main channel under the influence of temperature gradient, gravity, and surface tension. The angle of the triangular gradient structure is controlled to be 5° to 60°, and the length range is 5 to 20 mm. The triangular main channel provides the Laplace pressure differential driving force, and the mesh-like auxiliary channel expands the water collection area, improving the water collection efficiency compared to traditional surfaces. The water storage area is formed by the droplet collection layer; the super-hydrophilic triangular main channel and the mesh linear channel jointly drive the droplets to converge in a directional manner to the circular water storage area; Get the bionic water collection panel.

[0027] Example 2 This embodiment provides a bionic water collection panel, which is manufactured using the preparation method provided in Example 1. The bionic water collection panel manufactured using the above process is characterized.

[0028] Figure 1 The following are the schematic diagram of femtosecond laser processing, the test results of pulse frequency and contact angle, and the test results of pulse frequency and infrared emissivity. Figure 1 As shown in the figure, at 10 kHz, the material surface exhibits superhydrophobicity (>150°) and high infrared emissivity (>0.95); as the laser frequency increases, the surface wettability gradually changes from superhydrophobicity to superhydrophilicity, and the infrared emissivity also decreases accordingly; when the frequency reaches 80 kHz, the surface has superhydrophilicity (<20°) and low infrared emissivity (<0.03).

[0029] The samples prepared at 10 kHz and 80 kHz were ultrasonically cleaned with acetone and ethanol, dried with nitrogen, and then further observed by scanning electron microscopy and tested for contact angle. Figure 2Electron microscopy results show that at 10 kHz, the core-shell structure's central size is 5.57 µm; however, when the laser frequency is increased to 80 kHz, the structure's size significantly decreases to 0.634 µm. In contact angle measurements, a microsyringe precisely controls the injection of 2 to 5 µL of deionized water. A high-speed side-view camera captures the droplet morphology multiple times. After image processing and curve fitting, the corresponding contact angles were measured to be 156.6° and 10.6°, respectively, indicating that the sample surface exhibits superhydrophobic and superhydrophilic properties.

[0030] Example 3 This embodiment uses the bionic water collection panel of embodiment 2 for water collection. Figure 3 As shown, the system utilizes a three-stage structure consisting of a bionic water collection panel (A), a water channel (B), and a water storage tank (C). The panel and the channel are tilted at an angle of 5° to 30°, allowing gravity to naturally slide the collected droplets into the collection container without the need for additional power. The tank is seamlessly connected to the panel's edge guide, achieving zero-energy, evaporation-resistant, and continuous water collection.

[0031] In summary, the present invention uses femtosecond laser self-deposition technology to generate a dense metal oxide shell FeO on the surface of the material. x , giving it excellent corrosion resistance and adjustable hydrophilicity and hydrophobicity. Breaking through the limitations of traditional surface modification processes, the synergistic optimization of the material's corrosion resistance, wettability and infrared emissivity is achieved. Through precise control of the laser frequency, at 10 kHz, the material surface exhibits superhydrophobicity (>150°) and high infrared emissivity (>0.95); as the laser frequency increases, the surface wettability gradually changes from superhydrophobicity to superhydrophilicity, and the infrared emissivity also decreases accordingly; when the frequency reaches 80 kHz, the surface has superhydrophilicity (<20°) and low infrared emissivity (<0.03).

[0032] Based on this, the present invention designs a bionic structure with a wettability gradient to achieve autonomous liquid flow and efficient collection, and through the difference in infrared emissivity, achieve efficient water condensation at night, directional movement of droplets during the day, synergistic optimization of water collection, and achieve collaborative water collection during the day and night. Compared with traditional chemical coatings and subcrystalline phase structures to improve corrosion resistance, the present invention can not only achieve a wide range of wettability from superhydrophilic to superhydrophobic on a variety of metal substrates, but also can directly manufacture micron to nanometer three-dimensional channels, providing excellent wear resistance and corrosion resistance. In particular, the dense and chemically inert FeO x The shell effectively prevents the penetration of corrosive media, and Fe@FeO xThe core-shell structure provides a dual protection mechanism, further enhancing corrosion resistance. Unlike existing femtosecond laser technology, which primarily focuses on surface micro- and nanostructures, this method achieves multifunctional performance enhancement by precisely controlling the core-shell size through laser frequency regulation. While traditional biomimetic structures rely on the synergistic effects of morphology and coatings, the core-shell structure of this invention integrates multiple functions through component and interface design, simplifying process complexity and improving performance consistency and stability.

[0033] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A femtosecond laser-induced integrated preparation method for a controllable wettability and corrosion-resistant bionic water-collecting surface, characterized in that: The steps include: Femtosecond laser processing: Remove impurities from the surface of the iron substrate; then, in an air environment, use femtosecond laser to irradiate the surface of the iron substrate and adjust the repetition frequency to self-deposit Fe@FeO x The core-shell structure forms a super-hydrophobic droplet capture layer, a super-hydrophilic droplet transport layer, and a droplet collection layer on the surface of the iron substrate; Bionic water collection panel structure design: A bionic gradient pattern is fabricated on the surface of an iron substrate, including a super-hydrophobic network channel formed by a droplet capture layer, a super-hydrophilic triangular main channel and a network of linear channels formed by a droplet transport layer, and a water storage area formed by a droplet collection layer; Get the bionic water collection panel.

2. The integrated preparation method of a femtosecond laser-induced controllable wetting and corrosion-resistant biomimetic water-collecting surface according to claim 1, characterized in that: In the femtosecond laser processing, after the surface of the iron substrate is polished to a mirror surface, ultrasonic cleaning is performed with acetone, ethanol, and deionized water in sequence to remove impurities on the surface of the iron substrate, and the substrate is dried for later use.

3. The integrated preparation method of a femtosecond laser-induced controllable wettability and corrosion-resistant biomimetic water-collecting surface according to claim 1, characterized in that: In the femtosecond laser processing, the wavelength of the femtosecond laser is 515 nm, the pulse is 250 fs, and the energy density is 6×10 3 GW / cm 2 , the pulse frequency is 10~80 kHz.

4. The integrated preparation method of a femtosecond laser-induced controllable wettability and corrosion-resistant bionic water-collecting surface according to claim 3, characterized in that: The wettability and infrared emissivity of the iron substrate surface are adjusted by controlling the pulse frequency; as the pulse frequency increases, the Fe@FeO x As the size of the core-shell structure decreases, the wettability gradually changes from superhydrophobic to superhydrophilic, and the infrared emissivity decreases accordingly.

5. The integrated preparation method of a femtosecond laser-induced controllable wettability and corrosion-resistant bionic water-collecting surface according to claim 4, characterized in that: When the surface of the iron substrate is superhydrophobic, the water contact angle is greater than 150° and the infrared emissivity is greater than 0.95; when the surface is superhydrophilic, the water contact angle is less than 20° and the infrared emissivity is less than 0.

03.

6. The integrated preparation method of a femtosecond laser-induced controllable wettability and corrosion-resistant biomimetic water-collecting surface according to claim 1, characterized in that: In the bionic water collection panel structure design, the spacing between the superhydrophobic mesh channels is 0.1-1 mm, the angle between the oblique hydrophobic channels and the horizontal parallel hydrophobic channels is 15°-90°; the vertex angle of the superhydrophilic triangular main channel is 5°-60°; and the water storage area is a circular superhydrophilic area with a diameter of 2-5 mm.

7. A bionic water collection panel, characterized by: The method is as described in any one of claims 1 to 6.

8. Use of the bionic water collection panel as claimed in claim 7 to collect water in the air.

9. The use according to claim 8, characterized in that: The method comprises combining a bionic water collecting panel, a water guiding device and a water storage device; the water collected by the bionic water collecting panel slides to the water storage device through the water guiding device.

10. The use according to claim 9, characterized in that: The inclination angle between the bionic water collection panel and the water guide device is 5° to 30°.

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