Liquid metal-zero-valent iron core-shell structure catalytic material and preparation method thereof

Abstract

The present application relates to the field of environmental catalysis and water purification technology, and proposes a liquid metal-zero valence iron core-shell structure catalytic material and a preparation method thereof.The catalytic material comprises a gallium-indium alloy core and an amorphous zero valence iron shell coated on the surface of the core, the strong interaction at the core-shell interface promotes electron transfer, the core provides an electron transport channel, and the shell serves as a persulfate activation catalytic active site.The preparation method comprises the following steps: adding the gallium-indium alloy into a ferrous sulfate solution, performing cell disruption treatment under an ice water bath condition, collecting the precipitate through centrifugation, and then reacting the precipitate with a longan peel extract solution at room temperature to obtain a black powder-shaped catalyst through freeze-drying.The material can efficiently degrade organic pollutants in water under the synergistic condition of light and persulfate, the degradation rate of tetracycline hydrochloride reaches 100% within 15 min, and the cyclic stability is good;the material is dispersed in a polyvinyl alcohol matrix to form a photo-thermal catalytic hydrogel, and the hydrogel can realize efficient water evaporation purification under the driving of solar energy.

Description

Technical Field

[0001] This invention relates to the field of environmental catalysis and water purification technology, and more specifically, to the research and application of catalysts for advanced persulfate oxidation technology, solar-driven water evaporation and synergistic materials for catalytic degradation and photothermal water purification. Background Technology

[0002] Advanced persulfate-based oxidation technologies (PS-AOPs) are water treatment technologies that activate persulfates through heat, light, transition metals, or alkalis to generate highly reactive oxidizing species such as sulfate radicals, thereby efficiently degrading organic pollutants in water. Compared to traditional hydroxyl radical systems, sulfate radicals have higher redox potentials, longer half-lives, and a wider pH range, and can selectively attack electron-rich organic compounds. They can effectively mineralize recalcitrant pollutants such as antibiotics, dyes, and pesticides, and are suitable for groundwater remediation, soil leaching, and advanced industrial wastewater treatment. They offer advantages such as high oxidation efficiency, good reagent stability, ease of storage and transportation, and mild reaction conditions, making them a research hotspot in the field of environmental remediation.

[0003] However, despite the gradual exploration of catalyst optimization, photothermal synergy, and self-sufficient catalysis strategies in the PS-AOPs system, catalyst activity, stability, and long-term performance remain crucial factors affecting PS activation efficiency. In the past decade, while nano-zero-valent iron (nZVI) catalysts have demonstrated excellent persulfate (PS) activation capabilities in PS-AOPs, their tendency to aggregate, surface oxidation, and reduced active sites limit catalytic stability and reusability. Furthermore, the insufficient electron transport efficiency of the PS-AOPs system remains unresolved, limiting the PS activation rate and hindering efficient pollution degradation. Summary of the Invention

[0004] In view of this, the present invention proposes a liquid metal-zero-valent iron core-shell structured catalytic material and its preparation method to solve the problems existing in the prior art.

[0005] Specifically, the present invention provides the following technical solutions: A liquid metal-zero-valent iron core-shell structured catalytic material, characterized in that it comprises a core and a shell covering the surface of the core, wherein the core is a gallium-indium alloy and the shell is an amorphous zero-valent iron shell layer, and the core and the shell constitute a core-shell structure.

[0006] Optionally, the gallium-indium alloy contains 73.5% gallium by mass, 22.5% indium by mass, and 4% iron by mass.

[0007] Optionally, the thickness of the amorphous zero-valent iron shell layer is 10nm-500nm.

[0008] The preparation method of the above-mentioned catalytic material includes the following steps: Gallium-indium alloy was added to ferrous sulfate solution, and cell disruption was performed under ice-water bath conditions. The precipitate was then collected by centrifugation to obtain the intermediate product. The intermediate product was mixed with longan peel extract and stirred at room temperature. The reaction product was freeze-dried to obtain a black powdery liquid metal-zero-valent iron core-shell structured catalytic material LM@4Fe.

[0009] Optionally, the concentration of the ferrous sulfate solution is 0.6 mol / L, the cell disruption treatment is performed by continuous disruption for 10 min using a cell disruptor at a power of 240 kW, and the centrifugation conditions are 8000 rpm for 10 min. The longan peel extract was prepared by extracting dried and pulverized longan peel powder that had passed through a 60-mesh sieve, adding 75 mL of deionized water and 75 mL of anhydrous ethanol per 6 g of powder, and stirring in a constant temperature water bath at 60°C for 1 h. The intermediate product and the longan peel extract were stirred and reacted at room temperature for 1 hour. The freeze-drying process included freezing at -60°C for 4 hours and then freeze-drying for 12 hours.

[0010] The present invention further proposes a method for degrading organic pollutants in water using the above-mentioned catalytic material, comprising: adding the catalytic material and persulfate to a water body containing organic pollutants, and carrying out an advanced oxidative degradation reaction under light conditions.

[0011] Optionally, the organic pollutant is methyl orange, tetracycline hydrochloride, or methylene blue, and the persulfate is sodium persulfate. For every 30 mL of a pollutant solution with a concentration of 20 mg / L, 25 mg of catalyst and 0.1 g of sodium persulfate are added. The illumination uses a xenon lamp source with a light intensity of 1000 mW / cm². 2 After the reaction is complete, the catalyst material is collected by centrifugation, washed with deionized water and vacuum dried before being recycled.

[0012] The present invention further proposes a photothermal catalytic hydrogel, comprising a polyvinyl alcohol hydrogel matrix and a catalytic material uniformly dispersed in the matrix, wherein the amount of the catalytic material added to the hydrogel is 2 mg / mL, and the hydrogel is cylindrical with a diameter of 3 cm and a height of 0.5 cm.

[0013] The preparation method of the above-mentioned photothermal catalytic hydrogel includes the following steps: A polyvinyl alcohol solution was prepared by adding 15g of polyvinyl alcohol to 150mL of ultrapure water and heating in a water bath at 95℃ for 1.5h. The catalytic material was dispersed in water to form a dispersion. The dispersion was mixed and stirred at a ratio of 20 mL of polyvinyl alcohol solution to 1 mL of dispersion, and then injected into a mold. The mixture was first frozen at -60°C for 8 hours, and then freeze-dried for 24 hours to form the photothermal catalytic hydrogel.

[0014] The present invention further proposes the application of the above-mentioned photothermal catalytic hydrogel in water evaporation purification, including: placing the photothermal catalytic hydrogel on a hydrophilic substrate, so that the bottom of the photothermal catalytic hydrogel is in contact with the water to be purified, and using the photothermal effect to drive water evaporation under the irradiation of a xenon lamp light source to achieve water purification.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The liquid metal-zero-valent iron core-shell structured catalytic material LM@4Fe prepared in this invention exhibits highly efficient degradation activity for organic pollutants such as methyl orange, tetracycline hydrochloride, and methylene blue under persulfate activation and photocatalytic synergy. The degradation rate of tetracycline hydrochloride reaches 100% within 15 minutes, and remains above 80% after 5 cycles. Furthermore, when this material is loaded into a polyvinyl alcohol hydrogel, it can achieve a degradation rate of 3.233 kg·m³ under solar energy. -2 ·h -1 The water evaporation rate indicates that it effectively inhibits the aggregation and surface oxidation of zero-valent iron, improves catalytic stability and reusability, and provides technical support for the synergistic application of photothermal catalytic degradation and interfacial water evaporation purification. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings: Figure 1 This is a schematic diagram of the synthesis of LM@4Fe nanoparticles in an embodiment of the present invention; Figure 2 This is a characterization diagram of the LM@4Fe structure in an embodiment of the present invention; Figure 3 This is a schematic diagram of the preparation and photothermal evaporation test of LM@4Fe / PVA hydrogel in an embodiment of the present invention; Figure 4 The following is an example of the methyl orange (MO) removal performance of LM@4Fe in this invention: (a) is the kinetic curve of MO removal by LM, (b) is a comparison of the maximum adsorption capacity of MO by LM, LM@2Fe and LM@4Fe, (c) is the degradation curve of MO by LM@4Fe under different conditions, and (d) is the kinetic fitting of the degradation curve of MO by LM@4Fe under different conditions. Figure 5The following figures illustrate the degradation performance of LM@4Fe on tetracycline hydrochloride (TC) in this invention: (a) under no light and no PS conditions, (b) under light and no PS conditions, (c) under no light and PS conditions, (d) under light and PS conditions, (e) a pseudo-first-order kinetic fit of Figure (c); (f) a pseudo-first-order kinetic fit of Figure (d); (g) the UV absorption spectrum characterization of LM@4Fe on Tc under light and PS conditions; and (h) a comparison of the TC degradation performance of LM@4Fe under different conditions.

[0017] Figure 6 The following figures illustrate the degradation performance of LM@4Fe on methylene blue (MB) in this invention: (a) under no light and no PS conditions; (b) under light and no PS conditions; (c) under no light and PS conditions; (d) under light and PS conditions; (e) a pseudo-first-order kinetic fit of Figure (c); (f) a pseudo-first-order kinetic fit of Figure (d); (g) the UV absorption spectrum characterization of MB by LM@4Fe under light and PS conditions; and (h) a comparison of the MB degradation performance of LM@4Fe under different conditions. Figure 7 The present invention provides schematic diagrams of ESR test spectra in the embodiments, wherein (a) is the ESR spectrum of sulfate radicals and hydroxyl radicals under illumination; (b) is the ESR spectrum of singlet oxygen under illumination; (c) is the ESR spectrum of superoxide anion radicals under illumination; (d) is the ESR spectrum of sulfate radicals and hydroxyl radicals in darkness; (e) is the ESR spectrum of singlet oxygen in darkness; and (f) is the ESR spectrum of superoxide anion radicals in darkness.

[0018] Figure 8 The present invention provides a schematic diagram of evaporation testing in the embodiments. (a) shows the evaporation curves of LM@4Fe gels with different concentrations; (b) shows the evaporation curves of hydrogels with different materials; and (c) shows a summary diagram of evaporation.

[0019] Figure 9 The present invention provides infrared thermal imaging images of different materials in the embodiments, wherein (a) is a physical image of gels with different concentrations of LM@4Fe, (b) is a physical image of hydrogels of different materials, (c) is an infrared thermal imaging image of LM@4Fe materials with different concentrations at 60 min, and (d) is an infrared thermal imaging image of different materials at 60 min. Detailed Implementation

[0020] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] This embodiment proposes a liquid metal-zero-valent iron core-shell structure catalytic material, which has a core-shell structure with a gallium-indium alloy core containing the following elemental contents: gallium (Ga) 73.5%, indium (In) 22.5%, iron (Fe) 4%, and an amorphous zero-valent iron (Fe0) shell layer with a thickness of approximately 10-500 nm.

[0022] Among them, LM is the core, and the core-shell structure uniformly wrapped by Fe0 shell helps to improve the stability and functional properties of the material. At the same time, LM provides excellent conductivity and electron transport channels, Fe0 shell is the catalytic active site, and strong interaction between core and shell promotes electron transfer.

[0023] As a preferred embodiment, the preparation method of the liquid metal-zero-valent iron core-shell structured catalytic material LM@4Fe catalyst proposed in this embodiment is as follows: Figure 1 As shown, the specific steps include: 1. Preparation of Longan Peel Reducing Agent: Take 10g of fresh longan peel, dry it in a forced-air dryer at 60℃ for 24h, pulverize it with a pulverizer and pass it through a 60-mesh sieve. Weigh 6g of the powder and place it in a 250mL beaker. Add 75mL of deionized water and 75mL of anhydrous ethanol. Stir in a constant temperature water bath at 60℃ for 1h. After standing, take the supernatant and seal it for later use. 2. Preparation of ferrous sulfate solution: Weigh 2.49 g of ferrous sulfate (FeSO4·7H2O), dissolve it in deionized water and make up to 30 mL to obtain a 0.6 mol / L ferrous sulfate solution; 3. Preparation of LM@2Fe: Take a 50mL centrifuge tube, add 30mL of the above ferrous sulfate solution, accurately add 150μL of gallium-indium alloy (Ga-In alloy) with a pipette, place the centrifuge tube in an ice-water bath, put it in a cell disruptor (power 240KW) and continuously disrupt for 10min. After disruption, centrifuge at 8000rpm for 10min and collect the precipitate to obtain LM@2Fe. 4. Preparation of LM@4Fe: 45 mL of longan bark extract was added to the LM@2Fe precipitate and magnetically stirred at room temperature for 1 h. Then, it was transferred to a freeze-drying tray, frozen at -60℃ for 4 h, and freeze-dried in a freeze dryer for 12 h to obtain a black powdered LM@4Fe catalyst.

[0024] LM@4Fe structure characterization as follows Figure 2 As shown, 25 mg of LM@4Fe catalyst was added to a 30 mL solution containing the target pollutants (MO 20 mg / L, TC 20 mg / L, MB 5 mg / L), and PS was added as an oxidant. The solution was then heated under a xenon lamp source (380-1200 nm, 1000 mW / cm²). 2 The reaction under irradiation achieves efficient degradation of pollutants.

[0025] The ESR spectrum of LM@4Fe is as follows: Figure 7 As shown, by Figure 7 It can be seen that when DMPO is used as a spin trap, characteristic four-line spectral signals were detected in (a) and (b), corresponding to the generation of hydroxyl radical OH and sulfate radical SO4, respectively, and the hyperfine splitting constant conforms to the spectroscopic characteristics of typical nitric oxide radical adducts; in (c) and (d), characteristic signal peaks of superoxide anion radical O2 were observed, indicating that molecular oxygen undergoes single-electron reduction at the catalytic interface; in (e) and (f), triplet signals were detected using TEMP as a spin trap, confirming singlet oxygen ( 1 The presence of O2 was observed. The signal intensity of each active species was significantly enhanced under the coexistence of light and persulfate, which is consistent with the mechanism of the zero-valent iron shell in the LM@4Fe core-shell structure activating persulfate and the liquid metal core promoting photogenerated electron transfer. This confirms that the catalytic system achieves pollutant degradation by generating active oxygen species through multiple pathways.

[0026] This embodiment further proposes the preparation and evaporation testing steps of LM@4Fe / PVA photothermal catalytic hydrogel using LM@4Fe catalyst, such as... Figure 3 As shown, it includes: 1. PVA solution preparation: Add 15g of polyvinyl alcohol to 150mL of ultrapure water and heat in a 95℃ water bath for 1.5h until completely dissolved; 2. Mixing and molding: Add LM@4Fe catalyst (optimal addition amount 2mg / mL) to 1mL of water, mix with 20mL of PVA solution and stir, then pour into a mold; 3. Freeze-drying: Freeze at -60℃ for 8 hours, then freeze-dry for 24 hours to obtain a cylindrical hydrogel with a diameter of 3 cm and a height of 0.5 cm.

[0027] Place the hydrogel on a hydrophilic melamine sponge, immerse the bottom of the sponge in deionized water, and turn on the xenon lamp light source (1000mW / cm²). 2 Irradiation was performed, and the total mass change of the hydrogel and the water below it was measured every 10 minutes to calculate the evaporation rate. Statistical results are as follows Figure 8As shown in the figure, the evaporation test results indicate that the evaporation curves of LM@4Fe gels with different concentrations exhibit a continuous and stable mass loss trend with increasing light exposure time, and the evaporation rate increases with increasing catalyst concentration. A comparison of the evaporation curves of hydrogels made of different materials shows that the PVA hydrogel containing LM@4Fe catalyst material has significantly better evaporation performance than pure PVA hydrogel under the same light conditions. The total evaporation data shows that the water evaporation of the LM@4Fe / PVA hydrogel reaches 3.233 kg·m³. -2 ·h -1 It is a pure PVA hydrogel (1.535 kg·m³). -2 ·h -1 The efficiency of the core-shell catalytic material prepared in this embodiment is 2.1 times that of the solar-driven interfacial evaporation process, which confirms that the core-shell catalytic material has excellent photothermal conversion and mass transfer efficiency.

[0028] This embodiment further utilizes the prepared LM@4Fe to activate PS to degrade tetracycline hydrochloride (TC), including the following steps: 1. Experimental preparation: Prepare 30 mL of TC solution with a concentration of 20 mg / L, place it in a 50 mL beaker, and measure the initial absorbance (A0) at 360 nm using a spectrophotometer. 2. Reaction system setup: Add 25 mg LM@4Fe catalyst and 0.1 g sodium persulfate (PS) to the TC solution and stir until homogeneous; 3. Photodynamic response: Turn on the xenon lamp light source (simulating sunlight, intensity 1000mW / cm²). 2 Samples were taken at 5, 10, 15, and 20 minutes, and the absorbance was measured. ), calculate the degradation rate; 4. Results: The TC degradation rate reached 100% after 15 min, and the pseudo-first-order kinetic rate constant k = 0.2255 h. -1 The value is significantly higher than that under the dark + PS condition (k=0.0417h). -1 ).

[0029] Following the above method, TC was degraded using LM@4Fe catalysis. After the reaction was completed, the catalyst was collected by centrifugation at 8000 rpm for 10 min. Recycling: The collected catalyst was washed three times with deionized water, dried under vacuum, and the degradation experiment was repeated for a total of five cycles. Statistical results are as follows Figure 5 As shown, through Figure 5 It can be seen that, under the synergistic conditions of xenon lamp irradiation and the presence of sodium persulfate, the addition of 25 mg of catalyst and 0.1 g of sodium persulfate to 30 mL of 20 mg / L TC solution resulted in a 100% TC degradation rate after 15 min of reaction, with a pseudo-first-order kinetic rate constant k of 0.2255 h⁻¹.-1 This value is approximately 0.0417h of k under conditions of no light and with PS. -1 The degradation rate was 5.4 times that of light and persulfate activation, demonstrating a significant synergistic enhancement effect. In addition, after five cycles of use, the TC degradation rate remained above 80% within the same reaction time, indicating that the core-shell structured catalytic material has both high degradation activity and good reusability.

[0030] This embodiment further utilizes the prepared LM@4Fe to activate PS to degrade methyl orange (MO) and methylene blue (MB), including the following steps: Solutions of tetracycline hydrochloride (30 ml, 20 mg / L), methyl orange (30 ml, 20 mg / L), and methylene blue (30 ml, 5 mg / L) were prepared in 50 ml beakers. The initial absorbance was recorded at the maximum absorption wavelength (TC, MO, and TB were 360 ​​nm, 460 nm, and 664 nm, respectively) using a spectrophotometer. Then, 25 mg of catalyst was added, and a xenon lamp (wavelength range 380-1200 nm) was turned on. The solution was irradiated under a solar light intensity (1000 kW / cm²), which was measured using a power meter. The time was then started, and the absorbance was measured at different times to record the degradation efficiency of the pollutants.

[0031] The statistical results are as follows: Figure 4 and Figure 6 As shown, where, Figure 4 (a) The adsorption kinetics curves of MO on LM cores are presented. Figure 4 (b) By comparing the maximum adsorption amounts of LM, LM@2Fe and LM@4Fe, it is shown that the coating of the amorphous zero-valent iron shell layer significantly improves the material's ability to enrich MO. Figure 4 (c) and Figure 4 (d) Further, it is shown that under the synergistic conditions of light and persulfate, LM@4Fe exhibits rapid and efficient degradation characteristics of MO. Its degradation process conforms to the pseudo-first-order kinetic model, indicating that the electron transfer promoted by the strong interaction at the core-shell interface effectively accelerates the activation of persulfate and the generation of reactive oxygen species, thereby enabling the LM@4Fe catalyst to exhibit excellent catalytic degradation performance of methyl orange.

[0032] Figure 6 (a) to Figure 6 (d) The degradation curves of MB under four conditions are shown: no light and no PS, light and no PS, no light and PS, and light and PS. The results clearly show that LM@4Fe only exhibits significant degradation activity when light and persulfate are present at the same time. Figure 6 (e) and Figure 6The pseudo-first-order kinetic fit in (f) shows that the reaction rate under the coexistence of light and PS is much higher than that under the single condition. Figure 6 The UV absorption spectrum characterization of (g) directly reflects the significant decay of the MB characteristic absorption peak as the reaction proceeds. Figure 6 The comprehensive comparison of (h) further verifies the synergistic enhancement effect of light irradiation and persulfate activation, fully demonstrating that the LM@4Fe core-shell structure provides an electron transport channel through a liquid metal core and a zero-valent iron shell as a catalytic active site, thus achieving efficient degradation of methylene blue.

[0033] Figure 9 Infrared thermal imaging results showed that after 60 minutes of xenon lamp irradiation, the PVA hydrogel containing LM@4Fe catalyst exhibited a significantly higher surface temperature distribution compared to pure PVA hydrogel. The optimal LM@4Fe / PVA hydrogel ratio reached a surface temperature of 62℃. This temperature increase was positively correlated with evaporation performance, corresponding to an evaporation rate of 3.233 kg·m³. -2 ·h -1 It is a pure PVA hydrogel (1.535 kg·m³). -2 ·h -1 The efficiency of the LM@4Fe core-shell catalytic material is 2.1 times that of the solar-powered water evaporation purification system, indicating that the introduction of the LM@4Fe core-shell catalytic material effectively enhances the photothermal conversion efficiency of the system and provides strong thermodynamic support for solar-driven water evaporation purification.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A liquid metal-zero-valent iron core-shell structured catalytic material, characterized in that, It includes a core and a shell covering the surface of the core. The core is a gallium-indium alloy and the shell is an amorphous zero-valent iron shell layer. The core and the shell form a core-shell structure.

2. The catalytic material according to claim 1, characterized in that, The gallium-indium alloy contains 73.5% gallium by mass, 22.5% indium by mass, and 4% iron by mass.

3. The catalytic material according to claim 1, characterized in that, The thickness of the amorphous zero-valent iron shell layer is 10nm-500nm.

4. A method for preparing a catalytic material as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Gallium-indium alloy was added to ferrous sulfate solution, and cell disruption was performed under ice-water bath conditions. The precipitate was then collected by centrifugation to obtain the intermediate product. The intermediate product was mixed with longan peel extract and stirred at room temperature. The reaction product was freeze-dried to obtain a black powdery liquid metal-zero-valent iron core-shell structured catalytic material LM@4Fe.

5. The preparation method according to claim 4, characterized in that, The concentration of the ferrous sulfate solution was 0.6 mol / L. The cell disruption treatment was performed by a cell disruptor at a power of 240 kW for 10 min, and the centrifugation conditions were 8000 rpm for 10 min. The longan peel extract was prepared by extracting dried and pulverized longan peel powder that had passed through a 60-mesh sieve, adding 75 mL of deionized water and 75 mL of anhydrous ethanol per 6 g of powder, and stirring in a constant temperature water bath at 60°C for 1 h. The intermediate product and the longan peel extract were stirred and reacted at room temperature for 1 hour. The freeze-drying process included freezing at -60°C for 4 hours and then freeze-drying for 12 hours.

6. A method for degrading organic pollutants in water, characterized in that, The catalytic material according to any one of claims 1 to 3 and persulfate are added to water containing organic pollutants and subjected to advanced oxidative degradation reaction under light conditions.

7. The method according to claim 6, characterized in that, The organic pollutant is methyl orange, tetracycline hydrochloride, or methylene blue; the persulfate is sodium persulfate; and 25 mg of catalyst and 0.1 g of sodium persulfate are added for every 30 mL of pollutant solution with a concentration of 20 mg / L. The illumination uses a xenon lamp source with a light intensity of 1000 mW / cm². 2 After the reaction is complete, the catalyst material is collected by centrifugation, washed with deionized water and vacuum dried before being recycled.

8. A photothermal catalytic hydrogel, characterized in that, The invention comprises a polyvinyl alcohol hydrogel matrix and a catalytic material according to any one of claims 1 to 3 uniformly dispersed in the matrix, wherein the amount of the catalytic material added to the hydrogel is 2 mg / mL, and the hydrogel is cylindrical with a diameter of 3 cm and a height of 0.5 cm.

9. A method for preparing the photothermal catalytic hydrogel according to claim 8, characterized in that, Includes the following steps: A polyvinyl alcohol solution was prepared by adding 15g of polyvinyl alcohol to 150mL of ultrapure water and heating in a water bath at 95℃ for 1.5h. The catalytic material according to any one of claims 1 to 3 is dispersed in water to form a dispersion. The dispersion is mixed and stirred at a ratio of 20 mL of polyvinyl alcohol solution to 1 mL of dispersion and then injected into a mold. The dispersion is first frozen at -60°C for 8 h and then freeze-dried for 24 h to form the photothermal catalytic hydrogel.

10. The application of the photothermal catalytic hydrogel of claim 8 in water evaporation purification.

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