Composite photo-thermal material Fe / PANI / GF and preparation method and application thereof

Abstract

The invention belongs to the technical field of photo-thermal evaporation materials, and discloses a composite photo-thermal material Fe / PANI / GF and a preparation method and application thereof. The preparation method of the composite photo-thermal material Fe / PANI / GF comprises the following steps: taking graphite felt (GF), and activating at high temperature to obtain activated graphite felt; uniformly depositing polyaniline on the surface of the activated graphite felt by adopting a constant current method or a cyclic voltammetry to obtain acid-doped polyaniline (PANIES / GF); and dipping the acid-doped polyaniline in a ferric salt solution or a ferrous salt solution, and dispersing and loading Fe on the PANI nano-particle layer through Fe-N coordination to obtain the composite photo-thermal material Fe / PANI / GF. The method shows wide application prospects in the fields of seawater desalination, high-salinity wastewater treatment, heat-assisted power generation, photo-thermal driven sterilization, soil remediation and the like, and an innovative scheme is provided for solving the problems that a traditional photo-thermal material is low in efficiency, poor in stability, high in cost and the like.

Description

Technical Field

[0001] This invention relates to the field of photothermal evaporation materials technology, specifically to a composite photothermal material Fe / PANI / GF, its preparation method, and its applications. Background Technology

[0002] Solar-driven interfacial evaporation (SDIE) technology converts solar energy into heat energy through photothermal materials, driving seawater to evaporate and condense at the interface to obtain fresh water, providing a new approach for sustainable seawater desalination. The core of this technology lies in developing highly efficient photothermal conversion materials that simultaneously possess broad-spectrum absorption, rapid thermal conduction, and stable evaporation performance. Currently, carbon-based materials (such as graphene and carbon felt) are widely used due to their conductivity and chemical stability, but their limited light absorption bands and insufficient surface hydrophilicity make it difficult to achieve breakthroughs in photothermal efficiency. Furthermore, the scarcity of active sites on the surface of carbon-based materials makes it difficult to effectively load functional nanostructures, limiting multi-level performance optimization.

[0003] Polyaniline (PANI) has become a research hotspot for photothermal interface modification due to its broad-spectrum absorption and tunable oxidation state. However, in existing technologies, PANI is mostly loaded onto the substrate through chemical oxidation polymerization or physical coating, which easily leads to uneven distribution, weak bonding, and easy peeling or aggregation during long-term use, affecting stability. To improve the photothermal synergy, researchers have tried to introduce metal nanoparticles (such as Fe and Cu) into PANI, but traditional electrodeposition methods easily lead to metal particle aggregation and reduced element utilization. In addition, although existing high-temperature etching processes (such as Chinese invention patent document CN118847481A) can improve light absorption, high-temperature etching easily leads to microcracks in the carbon-based support, reducing mechanical strength, and the etching process greatly increases energy consumption. In summary, existing photothermal conversion materials cannot simultaneously achieve multiple properties, becoming a bottleneck restricting the practical application of SDIE.

[0004] Therefore, it is urgent to break through the performance limitations of traditional photothermal evaporation materials through material design and process innovation, and develop a composite photothermal material that combines high stability, high efficiency of photothermal conversion and high dispersion of metal load, so as to promote the practical development of SDIE technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art by providing a composite photothermal material Fe / PANI / GF, its preparation method, and its applications. This material has an excellent water evaporation rate and a simple and controllable preparation process. It can be widely used in solar seawater desalination, wastewater treatment, and other fields, and can effectively overcome the shortcomings of existing photothermal materials such as low evaporation rate, high cost, and complex preparation.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing the composite photothermal material Fe / PANI / GF, comprising the following steps: (1) Take graphite felt (GF), activate it at high temperature to obtain activated graphite felt; use the GF activated at high temperature as a carrier; The high-temperature activation is achieved by heating to 400°C-500°C at a rate of 4°C / min-6°C / min under conditions of 20°C-40°C, and holding at that temperature for 2h-6h. (2) Polyaniline is uniformly deposited on the surface of the activated graphite felt using a constant current method or a cyclic voltammetry method to obtain acid-doped polyaniline (PANI). ES / GF); Acid-doped polyaniline (PANI) ES After alkaline washing (pH 6-8) of / GF, intermediate-oxidized polyaniline (PANI) is obtained. EB / GF); (3) The acid-doped polyaniline is impregnated in an iron salt solution or a ferrous salt solution, and Fe is dispersed and loaded on the PANI nanoparticle layer through Fe-N coordination to obtain the composite photothermal material Fe / PANI / GF.

[0007] The composite photothermal material Fe / PANI / GF prepared by the method of the present invention has adjustable carrier surface properties to enhance stability; uniform PANI coating to maximize light absorption and heat conduction; uniform dispersion of metal sites to avoid agglomeration; and the overall material must have excellent hydrophilicity and durability.

[0008] As a preferred embodiment of the preparation method of the present invention, in step (1), before the high-temperature activation, the graphite felt is cleaned and dried; the cleaning is performed by ultrasonic cleaning with anhydrous ethanol and ultrapure water for 20 min-30 min in sequence; the drying is performed at a temperature of 55°C-65°C for 1.5 h-2.5 h.

[0009] In a preferred embodiment of the preparation method described in this invention, in step (2), the constant current method is as follows: Using the activated graphite felt as both cathode and anode, and a mixed solution of 0.1 M-0.2 M PANI and 0.5 M-1 M H2SO4 as the electrolyte, an electrolyte was prepared at a current density of 2 mA / cm². 2 -10 mA / cm 2 Electrodeposition was performed under the specified conditions for 5-10 minutes.

[0010] In a preferred embodiment of the preparation method described in this invention, in step (2), the cyclic voltammetry is as follows: Using the activated graphite felt as the working electrode, a platinum sheet as the counter electrode, a saturated calomel electrode as the reference electrode, and a mixed solution of 0.1 M-0.2 M PANI and 0.5 M-1 M H2SO4 as the electrolyte, 5-10 cycles were performed in a potential range of -0.2 V to 1.2 V; wherein the scan rate was 10 mV / s-50 mV / s.

[0011] As a preferred embodiment of the preparation method of the present invention, in step (2), the pH value is 6-8 during the alkaline washing; the alkaline solution is NaOH solution or KOH solution, and the soaking is carried out under static or magnetic stirring for 0.1h-6h.

[0012] As a preferred embodiment of the preparation method of the present invention, in step (3), the acid-doped polyaniline is impregnated in 20 mL-50 mL of ferric salt solution or ferrous salt solution; the impregnation is carried out under static or magnetic stirring, and the impregnation time is 2 h-6 h.

[0013] As a further preferred embodiment of the preparation method described in this invention, in step (3), the product is washed with deionized water after impregnation to completely remove free Fe ions.

[0014] As a further preferred embodiment of the preparation method described in this invention, in step (3), the product is dried at 50°C-70°C after washing.

[0015] Secondly, this invention provides a composite photothermal material prepared by the method described in the first aspect. The composite photothermal material Fe / PANI / GF of this invention uses graphite felt as a carrier, with polyaniline uniformly coated on the surface of the graphite felt via electrodeposition. Fe is stably and highly dispersedly loaded onto the polyaniline nanoparticle layer through Fe-N coordination. The Fe-N coordination loading is completed at room temperature, avoiding the degradation of the polyaniline structure caused by high-temperature treatment.

[0016] Thirdly, the present invention applies the composite photothermal material described in the second aspect to photothermal evaporation water treatment.

[0017] As a preferred embodiment of the application described in this invention, the water treatment includes seawater desalination or high-salinity wastewater treatment. Besides water treatment, based on its excellent photothermal conversion performance, the material also has great potential in photothermal-assisted power generation, photothermal-driven sterilization (using high surface temperatures to achieve physical sterilization), and soil thermal remediation (regulating moisture content to assist in pollutant removal).

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The composite photothermal material Fe / PANI / GF of this invention significantly improves photothermal evaporation performance and practicality through multi-level structural design and process innovation.

[0019] First, the composite photothermal material uses graphite felt (GF) as a substrate. Its three-dimensional fibrous structure provides an efficient channel for water molecule transport and has higher thermal and electrical conductivity than ordinary carbon felt. Combined with uniform electrochemical deposition coating of polyaniline (PANI), it achieves broad-spectrum absorption and rapid thermal conduction characteristics, effectively improving photothermal conversion efficiency. Simultaneously, an alkaline washing step enhances Fe-N coordination activity, and room-temperature impregnation achieves atomic-level Fe dispersion, avoiding high-temperature treatment. This enables efficient capture of solar radiation across the entire wavelength range, further enhancing light absorption and significantly increasing the water evaporation rate under solar energy drive.

[0020] Secondly, the preparation method of this invention has the advantages of being simple, controllable, and highly stable. Using the constant current method or cyclic voltammetry method for PANI electrodeposition allows for precise control of the polymer coating uniformity and bonding strength, overcoming the defects of traditional chemical polymerization that easily lead to coating peeling or uneven distribution. Furthermore, high-temperature activation pretreatment of GF enables dense coating of PANI, enhancing its surface hydrophilicity. Combined with Fe loading via chemical coordination rather than physical adsorption, this significantly improves the material's mechanical stability and cycle durability.

[0021] Finally, this invention combines low cost and multifunctionality. Using inexpensive graphite felt as a carrier and combining low-energy electrodeposition and impregnation processes significantly reduces preparation costs. Simultaneously, it completely eliminates the high-temperature etching step, with post-processing consisting only of washing and drying. The composite photothermal material Fe / PANI / GF of this invention shows broad application prospects in seawater desalination and high-salinity wastewater treatment, providing an innovative solution to the problems of low efficiency, poor stability, and high cost of traditional photothermal materials. Attached Figure Description

[0022] Figure 1 A scanning electron microscope image of GF prepared in Example 1; Figure 2 Scanning electron microscope image of PANI / GF prepared in Example 1; Figure 3 Scanning electron microscope image of Fe / PANI / GF prepared in Example 1; Figure 4 EDS elemental distribution image of Fe / PANI / GF prepared in Example 1; Figure 5 Evaporation rate curves for GF, PANI / GF, and Fe / PANI / GF prepared in Example 1; Figure 6Scanning electron microscope image of Fe / PANI / GF prepared in Example 2; Figure 7 Scanning electron microscope image of Fe / PANI / GF prepared in Example 3; Figure 8 Scanning electron microscope image of Fe / PANI / GF prepared in Example 4; Figure 9 Scanning electron microscope image of Fe / PANI / GF prepared in Example 5; Figure 10 Scanning electron microscope image of Fe / PANI / GF prepared for Comparative Example 1; Figure 11 Scanning electron microscope image of Fe / PANI / GF prepared for Comparative Example 2; Figure 12 Scanning electron microscope image of Fe / PANI / GF prepared for Comparative Example 3; Figure 13 Scanning electron microscope image of Fe / PANI / GF prepared for Comparative Example 4; Figure 14 Scanning electron microscope image of Fe / PANI / GF prepared for Comparative Example 5; Figure 15 Evaporation rate curves for Fe / PANI / GF prepared in Examples 1-5 and Comparative Example 1; Figure 16 Evaporation rate curves for Fe / PANI / GF prepared for comparative examples 1-5. Detailed Implementation

[0023] To better illustrate the objectives, technical solutions, and advantages of this invention, the invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0024] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0025] Example 1: A composite photothermal material The preparation method of this composite photothermal material includes the following steps: (1) Commercially available graphite felt (GF) was cut into 2.5 cm × 5 cm pieces and ultrasonically cleaned with anhydrous ethanol and ultrapure water for 20 min in sequence to remove impurities on the GF surface. Then it was dried at 60°C for 2 h to obtain clean GF. The clean GF was placed in a muffle furnace and heated to 450°C at a rate of 5°C / min under 30°C conditions, and held at this temperature for 2 h to obtain activated GF.

[0026] (2) In the two-electrode system, the PANI / GF composite material was prepared by constant current method, specifically: activated GF was used as the cathode and anode, and 50 mL of a mixed solution of PANI (0.1 M) and H2SO4 (0.5 M) was used as the electrolyte, at 2 mA / cm 2 Electrodeposition was performed at a current density for 10 min, followed by washing and drying to obtain ES-state PANI (PANI). ES / GF); PANI EB / GF by PANI ES / GF was obtained by stirring in 50 mL of 0.2 M NaOH solution for 30 min.

[0027] (3) Fe / PANI / GF composite material was prepared by impregnation method, specifically: cleaned PANI was impregnated with the PANI. ES The Fe / PANI / GF sample was immersed in 20 mL of 0.12 M FeSO4 solution and stirred for 2 h. The sample was then washed with ultrapure water to completely remove free Fe ions, thus obtaining the Fe / PANI / GF sample. After drying in a 60°C oven, the sample was stored at room temperature for later use, thus obtaining the composite photothermal material.

[0028] Figure 1 , Figure 2 and Figure 3 The images shown are scanning electron microscope (SEM) images of the photothermal evaporation materials GF, PANI / GF, and Fe / PANI / GF prepared in this embodiment. Figure 1 It can be seen that the original GF exhibits a typical three-dimensional cross-linked fiber network structure, with a smooth and flat fiber surface and an average diameter of approximately 10 μm. After loading PANI onto the activated GF surface using an electrodeposition method, a dense and ordered nanoparticle coating layer is formed on the modified PANI / GF surface. The PANI is tightly anchored to the GF fiber surface, significantly increasing the fiber surface roughness. Figure 2 This structural feature not only increases the specific surface area of ​​the material but also enhances surface hydrophilicity and light-harvesting ability through the introduction of polar groups (such as -NH-). Further, the Fe / PANI / GF composite material obtained through Fe coordination showed, in its SEM images, that the surface roughness of GF was further increased, and no obvious Fe aggregation was observed. Figure 3This indicates that a stable interfacial bond has formed between Fe and PANI.

[0029] Figure 4 The image shows the EDS elemental distribution of Fe / PANI / GF. The results indicate that Fe (red) and N (blue) elements exhibit a highly uniform spatial distribution on the fiber surface, confirming that Fe was successfully loaded into the PANI / GF system through coordination and formed a stable composite structure.

[0030] Figure 5 Evaporation rate curves for GF, PANI / GF, and Fe / PANI / GF are shown. Indoor evaporation performance tests show a 1 kWm -2 Under light intensity, the water evaporation rate of Fe / PANI / GF (2.03 kg / m³) -2 h -1 It is stronger than PANI EB / GF (1.78kgm) -2 h -1 ) and PANI ES / GF (1.87kgm) -2 h -1 Furthermore, the water evaporation rate of all three modified graphite felt composites was significantly higher than that of the unmodified graphite felt (0.67 kg / m³). -2 h -1 Compared with previously reported PANI-based photothermal evaporation materials, Fe / PANI / GF exhibits significant advantages: compared to PANI / ZrC / CA composite films (1.31 kgm³), Fe / PANI / GF demonstrates superior performance. -2 h -1 Increased by 54.9% (DOI:10.1016 / j.jechem.2023.08.018); compared to PANI / HNTs@PU fiber (1.61 kgm) -2 h -1 The efficiency was improved by 26.1% (DOI:10.1007 / s42765-022-00172-5); and it was superior to PANI / GO coating materials (1.42 kgm). -2 h -1 ) 42.9% (DOI:10.1002 / adfm.202209207).

[0031] Example 2: A composite photothermal material The preparation method of this composite photothermal material includes the following steps: (1) Commercially available graphite felt (GF) was cut into 2.5 cm × 5 cm pieces and ultrasonically cleaned with anhydrous ethanol and ultrapure water for 20 min in sequence to remove impurities on the GF surface. Then it was dried at 60°C for 2 h to obtain clean GF. The clean GF was placed in a muffle furnace and heated to 450°C at a rate of 5°C / min under 30°C conditions, and held at this temperature for 6 h to obtain activated GF.

[0032] (2) In a three-electrode system, PANI / GF composite material was prepared by cyclic voltammetry. Specifically, graphite felt was used as the working electrode, platinum sheet as the counter electrode, saturated calomel electrode as the reference electrode, and a mixed solution of 50 mL PANI (0.1 M) and H2SO4 (0.5 M) was used as the electrolyte. Ten cycles were performed in a potential range of -0.2 to 1.2 V (scan rate of 10 mV / s). After washing and drying, PANI was obtained. ES / GF.

[0033] (3) Fe / PANI / GF composite material was prepared by impregnation method, specifically: cleaned PANI was impregnated with the PANI. ES The Fe / PANI / GF sample was immersed in 50 mL of 0.12 M FeSO4 solution and stirred for 2 h. The sample was then washed with ultrapure water to completely remove free Fe ions, thus obtaining the Fe / PANI / GF sample. After drying in a 60°C oven, the sample was stored at room temperature for later use, thus obtaining the composite photothermal material.

[0034] Figure 6 This is a scanning electron microscope image of the photothermal evaporation material Fe / PANI / GF prepared in this embodiment. When Fe / PANI / GF was prepared using cyclic voltammetry (potential range -0.2-1.2V, scan rate 10mV / s, 10 cycles), the high scan rate and numerous cycles led to excessive deposition of PANI on the GF surface, forming loose, flocculent protrusions.

[0035] Example 3: A composite photothermal material The preparation method of this composite photothermal material includes the following steps: (1) Commercially available graphite felt (GF) was cut into 2.5 cm × 5 cm pieces and ultrasonically cleaned with anhydrous ethanol and ultrapure water for 20 min in sequence to remove impurities on the GF surface. Then it was dried at 60°C for 2 h to obtain clean GF. The clean GF was placed in a muffle furnace and heated to 450°C at a rate of 5°C / min under 30°C conditions, and held at this temperature for 2 h to obtain activated GF.

[0036] (2) In the two-electrode system, the PANI / GF composite material was prepared by constant current method, specifically: activated GF was used as the cathode and anode, and 50 mL of a mixed solution of PANI (0.2 M) and H2SO4 (1 M) was used as the electrolyte, at 10 mA / cm 2 Electrodeposition at a current density for 5 min, followed by washing and drying, yielded ES-state PANI (PANI). ES / GF).

[0037] (3) Fe / PANI / GF composite material was prepared by impregnation method, specifically: cleaned PANI was impregnated with the PANI. ES The Fe / PANI / GF sample was immersed in 20 mL of 0.12 M FeSO4 solution and stirred for 2 h. The sample was then washed with ultrapure water to completely remove free Fe ions, thus obtaining the Fe / PANI / GF sample. After drying in a 60°C oven, the sample was stored at room temperature for later use, thus obtaining the composite photothermal material.

[0038] Figure 7 This is a scanning electron microscope image of the photothermal evaporation material Fe / PANI / GF prepared in this embodiment. The concentration of PANI in the electrolyte was increased to 0.2 M, the concentration of H2SO4 was increased to 1 M, and the current density was increased to 10 mA / cm². 2 Excessive electrolyte concentration and rapid electrodeposition rate lead to uneven stacking of PANI nanoparticles, resulting in flocculent agglomeration.

[0039] Example 4: A composite photothermal material The preparation method of this composite photothermal material includes the following steps: (1) Commercially available graphite felt (GF) was cut into 2.5 cm × 5 cm pieces and ultrasonically cleaned with anhydrous ethanol and ultrapure water for 20 min in sequence to remove impurities on the GF surface. Then it was dried at 60°C for 2 h to obtain clean GF. The clean GF was placed in a muffle furnace and heated to 450°C at a rate of 5°C / min under 30°C conditions, and held at this temperature for 2 h to obtain activated GF.

[0040] (2) In the two-electrode system, the PANI / GF composite material was prepared by constant current method, specifically: activated GF was used as the cathode and anode, and 50 mL of a mixed solution of PANI (0.2M) and H2SO4 (1M) was used as the electrolyte, at 2 mA / cm 2 Electrodeposition at a current density for 5 min, followed by washing and drying, yielded ES-state PANI (PANI). ES / GF).

[0041] (3) Fe / PANI / GF composite material was prepared by impregnation method, specifically: cleaned PANI was impregnated with the PANI. ESThe Fe / PANI / GF sample was prepared by immersing it in 20 mL of 0.12 M FeSO4 solution and stirring for 6 h. The sample was then washed with ultrapure water to completely remove free Fe ions, and the Fe / PANI / GF sample was dried in an oven at 60°C and stored at room temperature for later use, thus obtaining the composite photothermal material.

[0042] Figure 8 This is a scanning electron microscope image of the photothermal evaporation material Fe / PANI / GF prepared in this embodiment. The concentration of PANI in the electrolyte was increased to 0.2 M, and the concentration of H2SO4 was increased to 1 M. The excessively high electrolyte concentration led to uneven stacking of the PANI nanoparticles, resulting in an irregular granular structure.

[0043] Example 5: A composite photothermal material The preparation method of this composite photothermal material includes the following steps: (1) Commercially available graphite felt (GF) was cut into 2.5 cm × 5 cm pieces and ultrasonically cleaned with anhydrous ethanol and ultrapure water for 20 min in sequence to remove impurities on the GF surface. Then it was dried at 60°C for 2 h to obtain clean GF. The clean GF was placed in a muffle furnace and heated to 450°C at a rate of 5°C / min under 30°C conditions, and held at this temperature for 6 h to obtain activated GF.

[0044] (2) In a three-electrode system, PANI / GF composite material was prepared by cyclic voltammetry. Specifically, graphite felt was used as the working electrode, platinum sheet as the counter electrode, saturated calomel electrode as the reference electrode, and a mixed solution of 50 mL PANI (0.2 M) and H2SO4 (1 M) was used as the electrolyte. Five cycles were performed in the potential range of -0.2 to 0.9 V (scan rate of 50 mV / s). After washing and drying, PANI was obtained. ES / GF.

[0045] (3) Fe / PANI / GF composite material was prepared by impregnation method, specifically: cleaned PANI was impregnated with the PANI. ES The Fe / PANI / GF sample was prepared by immersing it in 20 mL of 0.12 M FeSO4 solution and stirring for 6 h. The sample was then washed with ultrapure water to completely remove free Fe ions, and the Fe / PANI / GF sample was dried in an oven at 60°C and stored at room temperature for later use, thus obtaining the composite photothermal material.

[0046] Figure 9 This is a scanning electron microscope image of the photothermal evaporation material Fe / PANI / GF prepared in this embodiment. The high scanning rate (50 mV / s) and fluctuations in electrodeposition parameters led to abnormal local crosslinking of the PANI segments, forming an irregular flocculent structure.

[0047] Comparative Example 1: A composite photothermal material The preparation method of this composite photothermal material includes the following steps: (1) Commercially available graphite felt (GF) was cut into 2.5 cm × 5 cm pieces and ultrasonically cleaned with anhydrous ethanol and ultrapure water for 20 min in sequence to remove impurities on the surface of GF. Then it was dried at 60°C for 2 h to obtain clean GF.

[0048] (2) In the two-electrode system, the PANI / GF composite material was prepared by constant current method, specifically: clean GF was used as the cathode and anode, and 50 mL of a mixed solution of PANI (0.2M) and H2SO4 (1M) was used as the electrolyte, at 2 mA / cm 2 Electrodeposition was performed at a current density for 10 min, followed by washing and drying to obtain ES-state PANI (PANI). ES / GF); (3) Fe / PANI / GF composite material was prepared by impregnation method, specifically: cleaned PANI was impregnated with the PANI. ES The Fe / PANI / GF sample was prepared by immersing it in 20 mL of 0.12 M FeSO4 solution and stirring for 6 h. The sample was then washed with ultrapure water to completely remove free Fe ions, and the Fe / PANI / GF sample was dried in an oven at 60°C and stored at room temperature for later use, thus obtaining the composite photothermal material.

[0049] Figure 10 This is a scanning electron microscope image of the photothermal evaporation material Fe / PANI / GF prepared in this comparative example. The PANI coating on the GF surface is discontinuous, with a large number of exposed areas, and the PANI layer appears as a broken, flocculent structure.

[0050] Comparative Example 2: A composite photothermal material The preparation method of this composite photothermal material includes the following steps: (1) Commercially available graphite felt (GF) was cut into 2.5 cm × 5 cm pieces and ultrasonically cleaned with anhydrous ethanol and ultrapure water for 20 min in sequence to remove impurities from the GF surface. Then it was dried at 60°C for 2 h to obtain clean GF. The clean GF was placed in a muffle furnace and heated to 450°C at a rate of 5°C / min under 30°C conditions, and held at this temperature for 1 h to obtain high-temperature treated GF.

[0051] (2) In the two-electrode system, the PANI / GF composite material was prepared by constant current method, specifically: high-temperature treated GF was used as the cathode and anode, and 50 mL of a mixed solution of PANI (0.1 M) and H2SO4 (0.5 M) was used as the electrolyte, at 2 mA / cm 2Electrodeposition was performed at a current density for 10 min, followed by washing and drying to obtain ES-state PANI (PANI). ES / GF).

[0052] (3) Fe / PANI / GF composite material was prepared by impregnation method, specifically: cleaned PANI was impregnated with the PANI. ES The Fe / PANI / GF sample was prepared by immersing it in 20 mL of 0.12 M FeSO4 solution and stirring for 6 h. The sample was then washed with ultrapure water to completely remove free Fe ions, and the Fe / PANI / GF sample was dried in an oven at 60°C and stored at room temperature for later use, thus obtaining the composite photothermal material.

[0053] Figure 11 This is a scanning electron microscope image of the photothermal evaporation material Fe / PANI / GF prepared in this comparative example. The high-temperature activation time of GF was only 1 hour, resulting in insufficient surface activation sites and a thin and uneven PANI coating layer. After Fe loading, due to the discontinuity of the PANI substrate, a small number of agglomerated particles appeared, leading to poor overall surface smoothness and the failure to form a dense composite structure.

[0054] Comparative Example 3: A composite photothermal material The preparation method of this composite photothermal material includes the following steps: (1) Commercially available graphite felt (GF) was cut into 2.5 cm × 5 cm pieces and ultrasonically cleaned with anhydrous ethanol and ultrapure water for 20 min in sequence to remove impurities from the GF surface. Then it was dried at 60°C for 2 h to obtain clean GF. The clean GF was placed in a muffle furnace and heated to 450°C at a rate of 5°C / min under 30°C conditions, and held at this temperature for 7 h to obtain high-temperature treated GF.

[0055] (2) In the two-electrode system, the PANI / GF composite material was prepared by constant current method, specifically: high-temperature treated GF was used as the cathode and anode, and 50 mL of a mixed solution of PANI (0.1 M) and H2SO4 (0.5 M) was used as the electrolyte, at 2 mA / cm 2 Electrodeposition was performed at a current density for 10 min, followed by washing and drying to obtain ES-state PANI (PANI). ES / GF).

[0056] (3) Fe / PANI / GF composite material was prepared by impregnation method, specifically: cleaned PANI was impregnated with the PANI. ES The Fe / PANI / GF sample was prepared by immersing it in 20 mL of 0.12 M FeSO4 solution and stirring for 6 h. The sample was then washed with ultrapure water to completely remove free Fe ions, and the Fe / PANI / GF sample was dried in an oven at 60°C and stored at room temperature for later use, thus obtaining the composite photothermal material.

[0057] Figure 12 This is a scanning electron microscope image of the photothermal evaporation material Fe / PANI / GF prepared in this comparative example. The high-temperature activation time of GF was extended to 7 hours, resulting in over-activation and slight etching damage to the fiber surface. During PANI deposition, it easily aggregated at these damaged areas, forming locally protruding flocculent structures. Fe tended to agglomerate in the flocculent PANI regions, failing to achieve uniform dispersion.

[0058] Comparative Example 4: A composite photothermal material The preparation method of this composite photothermal material includes the following steps: (1) Commercially available graphite felt (GF) was cut into 2.5 cm × 5 cm pieces and ultrasonically cleaned with anhydrous ethanol and ultrapure water for 20 min in sequence to remove impurities from the GF surface. Then it was dried at 60°C for 2 h to obtain clean GF. The clean GF was placed in a muffle furnace and heated to 300°C at a rate of 3°C / min under 30°C conditions, and held at this temperature for 2 h to obtain high-temperature treated GF.

[0059] (2) In the two-electrode system, the PANI / GF composite material was prepared by constant current method, specifically: high-temperature treated GF was used as the cathode and anode, and 50 mL of a mixed solution of PANI (0.1 M) and H2SO4 (0.5 M) was used as the electrolyte, at 2 mA / cm 2 Electrodeposition was performed at a current density for 10 min, followed by washing and drying to obtain ES-state PANI (PANI). ES / GF).

[0060] (3) Fe / PANI / GF composite material was prepared by impregnation method, specifically: cleaned PANI was impregnated with the PANI. ES The Fe / PANI / GF sample was prepared by immersing it in 20 mL of 0.12 M FeSO4 solution and stirring for 6 h. The sample was then washed with ultrapure water to completely remove free Fe ions, and the Fe / PANI / GF sample was dried in an oven at 60°C and stored at room temperature for later use, thus obtaining the composite photothermal material.

[0061] Figure 13 Scanning electron microscope image of the photothermal evaporation material Fe / PANI / GF prepared for this comparative example.

[0062] The GF high-temperature activation uses a low heating rate of 3°C / min and a final temperature of only 300°C, resulting in insufficient activation and limited improvement in surface hydrophilicity. As a result, PANI is difficult to anchor tightly and exhibits a discontinuous sheet-like coating morphology.

[0063] Comparative Example 5: A composite photothermal material The preparation method of this composite photothermal material includes the following steps: (1) Commercially available graphite felt (GF) was cut into 2.5 cm × 5 cm pieces and ultrasonically cleaned with anhydrous ethanol and ultrapure water for 20 min in sequence to remove impurities from the GF surface. Then it was dried at 60°C for 2 h to obtain clean GF. The clean GF was placed in a muffle furnace and heated to 600°C at a rate of 7°C / min under 30°C conditions, and held at this temperature for 2 h to obtain high-temperature treated GF.

[0064] (2) In the two-electrode system, the PANI / GF composite material was prepared by constant current method, specifically: high-temperature treated GF was used as the cathode and anode, and 50 mL of a mixed solution of PANI (0.1 M) and H2SO4 (0.5 M) was used as the electrolyte, at 2 mA / cm 2 Electrodeposition was performed at a current density for 10 min, followed by washing and drying to obtain ES-state PANI (PANI). ES / GF).

[0065] (3) Fe / PANI / GF composite material was prepared by impregnation method, specifically: cleaned PANI was impregnated with the PANI. ES The Fe / PANI / GF sample was prepared by immersing it in 20 mL of 0.12 M FeSO4 solution and stirring for 6 h. The sample was then washed with ultrapure water to completely remove free Fe ions, and the Fe / PANI / GF sample was dried in an oven at 60°C and stored at room temperature for later use, thus obtaining the composite photothermal material.

[0066] Figure 14 This is a scanning electron microscope image of the photothermal evaporation material Fe / PANI / GF prepared in this comparative example. The high-temperature activation of GF was carried out at a high heating rate of 7°C / min and the final temperature reached 600°C. The excessively high temperature and heating rate caused microcracks to appear on the surface of the GF fibers. When PANI was deposited, it was easy to fill the cracks, but the overall coating was uneven, resulting in the accumulation of particles of varying sizes.

[0067] Experimental example: The indoor water evaporation performance of the composite photothermal materials prepared in Examples 1-5 and Comparative Examples 1-5 was tested. The indoor evaporation performance was tested according to commonly used experimental methods for photothermal evaporation materials (e.g., DOI:10.1002 / adfm.202209207), using an AM1.5G standard solar simulator with 1 kWm of power. -2 Light intensity and evaporation rate are calculated by real-time monitoring of water mass loss.

[0068] The evaporation rate curves of the composite photothermal materials prepared in Examples 1-5 and Comparative Example 1 are shown below. Figure 15 As shown. The evaporation rate curves of Fe / PANI / GF prepared in Comparative Examples 2-4 are shown in the figure. Figure 16 As shown.

[0069] Indoor evaporation performance tests showed 1 kW m -2 Under light intensity, the water evaporation rate of Fe / PANI / GF in Example 1 (2.03 kg / m³) -2 h -1 The water evaporation rate of Fe / PANI / GF in Example 2 was 1.94 kg / m³. -2 h -1 While the flocculent region increases the specific surface area, its loose structure leads to increased light reflectivity and discontinuous heat conduction paths, resulting in easy local heat loss. Furthermore, the flocculent PANI has weak adhesion to the GF substrate, making it prone to peeling during long-term immersion or repeated use, resulting in a low evaporation rate (1.94 kg / m³). -2 h -1 This also confirms that the flocculent structure has a slightly negative effect on performance. The water evaporation rate of Fe / PANI / GF in Example 3 was 1.99 kg / m³. -2 h -1 The water evaporation rate of Fe / PANI / GF in Example 4 was 1.98 kg / m³. -2 h -1 The water evaporation rate of Fe / PANI / GF in Example 5 was 1.91 kg / m³. -2 h -1 .

[0070] The water evaporation rate of Fe / PANI / GF in Comparative Example 1 was 1.42 kg / m³. -2 h -1 (30.1% lower than Example 1). The water evaporation rate of Fe / PANI / GF in Comparative Example 2 was 1.39 kg / m³. -2 h -1 The water evaporation rate of Fe / PANI / GF in Comparative Example 3 was 1.47 kg / m³. -2 h -1 The water evaporation rate of Fe / PANI / GF in Comparative Example 4 was 1.49 kg / m³. -2 h -1 The water evaporation rate of Fe / PANI / GF in Comparative Example 5 was 1.56 kg / m³. -2 h -1 It can be seen that the high-temperature activation of GF significantly affects the material's performance. Unactivated GF has fewer hydrophilic groups on its surface, and PANI cannot be effectively anchored, leading to uneven coating and Fe coordination failure.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a composite photothermal material Fe / PANI / GF, characterized in that, Includes the following steps: (1) Take graphite felt and activate it at high temperature to obtain activated graphite felt; The high-temperature activation is achieved by heating to 400°C-500°C at a rate of 4°C / min-6°C / min under conditions of 20°C-40°C, and holding at that temperature for 2h-6h. (2) Polyaniline is uniformly deposited on the surface of the activated graphite felt using a constant current method or a cyclic voltammetry method to obtain acid-doped polyaniline; (3) The acid-doped polyaniline is impregnated in an iron salt solution or a ferrous salt solution to obtain the composite photothermal material Fe / PANI / GF.

2. The preparation method according to claim 1, characterized in that, In step (1), before the high-temperature activation, the graphite felt is cleaned and dried; the cleaning is performed by ultrasonic cleaning with anhydrous ethanol and ultrapure water for 20 min-30 min in sequence; the drying is performed at a temperature of 55°C-65°C for 1.5 h-2.5 h.

3. The preparation method according to claim 1, characterized in that, In step (2), the constant current method is as follows: Using the activated graphite felt as both cathode and anode, and a mixed solution of 0.1 M-0.2 M PANI and 0.5 M-1 M H2SO4 as the electrolyte, an electrolyte was prepared at a current density of 2 mA / cm². 2 -10 mA / cm 2 Electrodeposition was performed under the specified conditions for 5-10 minutes.

4. The preparation method according to claim 1, characterized in that, In step (2), the cyclic voltammetry method is as follows: Using the activated graphite felt as the working electrode, a platinum sheet as the counter electrode, a saturated calomel electrode as the reference electrode, and a mixed solution of 0.1 M-0.2 M PANI and 0.5 M-1 M H2SO4 as the electrolyte, 5-10 cycles were performed in a potential range of -0.2 V to 1.2 V; wherein the scan rate was 10 mV / s-50 mV / s.

5. The preparation method according to claim 1, characterized in that, In step (3), the acid-doped polyaniline is impregnated in 20 mL to 50 mL of ferric salt solution or ferrous salt solution; the impregnation is carried out under static or magnetic stirring for 2 h to 6 h.

6. The preparation method according to claim 5, characterized in that, In step (3), the product is washed with deionized water after impregnation.

7. The preparation method according to claim 6, characterized in that, In step (3), the product is dried at 50°C-70°C after washing.

8. A composite photothermal material, characterized in that, It is prepared by any one of the preparation methods described in claims 1-7.

9. The application of the composite photothermal material according to claim 8 in photothermal evaporation water treatment, thermal-assisted power generation, photothermal-driven sterilization, and soil remediation.

10. The application according to claim 9, characterized in that, The water treatment includes seawater desalination or high-salinity wastewater treatment.

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