Method for preparing a photothermal water evaporator based on conjugated ligand-based znmo polynuclear cluster photothermal material

Abstract

The present application relates to the technical field of water evaporator, in particular to a method for preparing a photo-thermal water evaporator based on conjugated ligand ZnMo multi-nuclear cluster photo-thermal material. Under the condition of hydrothermal method, zinc citrate dihydrate, molybdic acid and pyridine / 2,2-bipyridine / 1,10-phenanthroline are introduced into the experimental process as a raw material, through washing, high temperature annealing reaction, cooling to room temperature, the conjugated ligand ZnMo multi-nuclear cluster photo-thermal material powder is obtained, which is blended with polyvinylidene fluoride, and through vacuum filtration and drying, the DMF solvent in the mixed solution is extracted, the polyoxometalate and PVDF are uniformly attached to the surface of the nylon film, the obtained filtrate is dried in a room temperature environment, then the film slice is prepared, and the photo-thermal water evaporator is prepared. The photo-thermal water evaporator prepared by this method not only has excellent performance and high stability, but also has excellent water evaporation capacity, and shows great potential in the field of seawater desalination.

Description

Technical Field

[0001] This invention relates to the field of water evaporator technology, and specifically to a method for preparing a photothermal evaporator based on ZnMo multinuclear cluster photothermal material with conjugated ligands. Background Technology

[0002] Resource scarcity has become a global problem. Seawater, as the most abundant water resource on Earth, plays a crucial role in alleviating the water crisis through desalination technology. Currently, common desalination methods such as distillation and reverse osmosis have revealed drawbacks such as high energy consumption, complex equipment construction, and high costs. Developing new desalination technologies that combine high efficiency and low cost has become a hot research topic.

[0003] Metal-organic framework (MOF) materials, with their unique pore structure, flexible customizable structure and function, are not only green and environmentally friendly with a wide range of applications, but also simple and inexpensive to prepare.

[0004] Metal-organic frameworks (MOFs), a unique branch of the MOF family, contain active sites composed of two different metal elements. These active sites are either bridged together by organic ligands or are adjacent to each other in the MOF crystal structure. Researchers design and synthesize these materials by integrating and optimizing the catalytic properties of the two metals. By precisely controlling the synergistic effect between the two metals, catalytic activity is effectively enhanced, the selectivity of catalytic reactions is improved, and the stability of the catalyst during long-term use is ensured. Furthermore, the unique spatial structure and highly tunable structural characteristics of bimetallic MOFs greatly enhance their ability to interact with specific substances during catalysis, significantly improving light absorption efficiency and opening up broader application prospects in fields such as photocatalysis.

[0005] With the freshwater resource crisis becoming increasingly severe, solar-driven water evaporation technology is considered an ideal solution for sustainable seawater desalination. However, existing photothermal materials still face serious challenges in practical applications, with low photothermal conversion efficiency: traditional materials (such as carbon-based and metal oxides) have narrow light absorption ranges and insufficient solar energy utilization, resulting in evaporation rates generally below 1.0 kg·m³. - ² h - ¹, making it difficult to meet actual needs. Poor environmental stability: Long-term exposure to light, high temperature and seawater corrosion environments can easily cause photochemical degradation or structural collapse of the material, resulting in significant performance degradation. Frequent replacement further increases the cost of use.

[0006] The paper "Preparation Method of Self-Healing Polymer Photothermal Materials Based on ZnMo Multi-Clusters" (CN118813036A) describes a hydrothermal method that uses zinc citrate dihydrate, molybdic acid, and 2-mercapto-5-methoxybenzimidazole ligand as raw materials to prepare a ZnMo multi-cluster photothermal material precursor. The precursor is then obtained through washing, high-temperature annealing, and cooling to room temperature. This ZnMo multi-cluster photothermal material powder is then blended with a polymer to prepare a self-healing photothermal water evaporation material. However, this method suffers from several problems: limited ligand selection makes it difficult to control light absorption; the porous structure is susceptible to water erosion, resulting in insufficient cycle stability; the synthesis process involves multiple modification steps, leading to high industrialization costs; the use of toxic reagents is environmentally unfriendly; the material exhibits poor stability and weak light absorption; and the preparation process is complex. Although bimetallic MOF materials have shown potential for photothermal applications through synergistic effects, high-performance materials (such as noble metal nanoparticles and complex MOFs) rely on energy-intensive synthesis routes (such as high-temperature calcination and vacuum deposition).

[0007] Therefore, developing a photothermal evaporator that combines high efficiency in photothermal conversion, long-term stability, low cost, and environmental friendliness has become the key to breaking through technological bottlenecks. Summary of the Invention

[0008] In view of this, the present invention provides a method for preparing a photothermal evaporator based on ZnMo multinuclear cluster photothermal material with conjugated ligands. The prepared water evaporator not only has excellent performance and high stability, but also has excellent water evaporation capacity, showing great potential in the field of seawater desalination.

[0009] To solve the above problems, the technical solution adopted by the present invention is: a method for preparing a photothermal evaporator based on ZnMo multinuclear cluster photothermal material with conjugated ligands, characterized in that, Step 1: In a dry, inert atmosphere glove box, mix 0.2–0.4 g of molybdic acid, 0.1–0.3 g of zinc citrate dihydrate and 0.05–0.3 g of polypyridine compound, seal the mixture in a 25 mL polytetrafluoroethylene-lined reactor, then inject 5.00 mL of anhydrous N,N-dimethylformamide into the reactor, seal the liner, place the liner in an ultrasonic instrument, and ultrasonically disperse the mixture at 40 kHz for 10–15 minutes until a homogeneous and transparent solution is formed. Step 2: Place the reactor containing the mixed solution into an autoclave and react in a high-temperature oven for 3 days. After the reaction, cool to room temperature, remove the reactor, and wash the crystals three times with N,N-dimethylformamide at 0°C to remove impurities adsorbed on the surface. Then, perform vacuum filtration to collect the blue-black blocky crystals, which is the crude product A. Step 3: The crude product A is loaded into a Soxhlet extractor and extracted by continuous reflux at 75-95°C for 48 hours using anhydrous N,N-dimethylformamide as solvent to obtain dark blue lustrous crystals. The dark blue lustrous crystals are replaced with anhydrous ethanol three times and transferred to a vacuum drying oven for drying for 12 hours to obtain blue-black crystals, i.e., product A. Step 4: Take product A in an agate mortar cooled by liquid nitrogen and grind it to the particle size in an inert atmosphere glove box to obtain powder B; Step 5: Disperse 20-40 mg of powder B and 5-14 mg of polyvinylidene fluoride in 5 mL of N,N-dimethylformamide and stir for 1 h to prepare a homogeneous mixed solution. Use a vacuum filtration device to filter the homogeneous solution with a nylon membrane with a pore size of 220 nm. After filtration, place the obtained filtrate in a room temperature environment for drying. Then cut the membrane into pieces with a diameter of 3 cm and assemble them into a photothermal evaporator.

[0010] Furthermore, in step 1), the polypyridine compound is 1,10-phenanthroline, pyridine, or 2,2-bipyridine.

[0011] Furthermore, in step 2), the temperature of the high-temperature oven is 140–160°C.

[0012] Furthermore, in step 3), the temperature of the vacuum drying oven is 60–80°C.

[0013] Furthermore, in step 4), the grinding time in the mortar is 10-20 minutes.

[0014] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention introduces conjugated ligands (pyridine, 2,2-bipyridine, 1,10-o-phenanthroline organic ligands) to construct ZnMo polynuclear clusters with broad-spectrum absorption, and enhances light-harvesting ability through π-π conjugation; ZnMo clusters with different numbers of nuclei can be flexibly designed to meet diverse needs, and have strong coordination ability and metal diversity, controllable spatial configuration, and low cost and easy availability, thus avoiding the use of potentially toxic reagents, which is more in line with the concept of green chemistry.

[0015] (2) The present invention only requires the synthesis of ZnMo polynuclear clusters by a one-step hydrothermal method and then direct blending with PVDF to form a film, avoiding high temperature / toxic reagents, and simplifying device assembly by vacuum filtration to form a film. The process steps are simple and do not require complex polymer synthesis.

[0016] (3) The o-phenanthroline cluster in the ZnMo polynuclear cluster based on conjugated ligand prepared by the present invention has better cycling stability. In 10 light irradiation cycles, the temperature of the o-phenanthroline cluster remained stable at 80℃ and the evaporation rate did not decrease, indicating that it has excellent long-term stability.

[0017] (4) The o-phenanthroline clusters in the ZnMo polynuclear clusters prepared by this invention have strong photothermal conversion efficiency and evaporation performance, significantly improving the light absorption capacity of the material. Under 1 solar intensity, the evaporation rate of the o-phenanthroline clusters reaches 1.25 kg m³. - ² h - ¹, far exceeding pure water (0.43 kg m - ² h - ¹), and the evaporation efficiency is over 85%.

[0018] (5) In the dispersion preparation step of the photothermal evaporator assembly, the conjugated ZnMo polynuclear cluster powder B and polyvinylidene fluoride (PVDF) are accurately weighed and dispersed together in 5 mL of N,N-dimethylformamide (DMF). This process can bind to the active sites on the surface of ZnMo polynuclear cluster (powder B) through hydrogen bonds or van der Waals forces, preventing the material from falling off after filtration and film formation, improving the mechanical stability of the device, and intertwining with powder B particles to form a porous structure, which is conducive to the rapid transport of water molecules to the evaporation interface.

[0019] (6) In the preparation method of the present invention, after filtration, Soxhlet extract is continuously refluxed. The solvent reflux circulation continuously dissolves small molecule impurities embedded in the crystal with fresh hot solvent (DMF), which improves the efficiency of continuous extraction of impurities, preferentially washes out small molecule impurities, and retains large-size crystal products. The slow reflux process may promote the self-repair of crystal defects, obtain higher quality single crystals, improve the utilization rate of sunlight, and have a more efficient light-harvesting ability.

[0020] (7) The present invention adopts an environmentally friendly and controllable chemical preparation process, which is simple and quick. Attached Figure Description

[0021] Figure 1 This is a flowchart of the preparation method of ZnMo multinuclear cluster photothermal material based on conjugated ligands in this invention.

[0022] Figure 2 is the infrared spectrum of the ZnMo polynuclear cluster photothermal material based on conjugated ligands in this invention; where (a) is the infrared spectrum of o-phenanthroline; (b) is the infrared spectrum of 2,2-bipyridine; and (c) is the infrared spectrum of pyridine.

[0023] Figure 3 This is a comparison chart of mass loss under one solar radiation intensity in this invention.

[0024] Figure 4 This is a comparison chart of the evaporation rate and evaporation efficiency of all samples under one sun irradiation in this invention.

[0025] Figure 5This is a cyclic image of a ZnMo multinucleus based on conjugated ligands being irradiated 10 times under one solar intensity, according to the present invention.

[0026] Figure 6 This invention describes the photothermal conversion behavior of ZnMo multinuclear clusters based on conjugated ligands over 1200 seconds in different powder samples under 0.1 W / cm² xenon lamp irradiation. Detailed Implementation

[0027] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0028] This invention, based on a vacuum filtration film-forming method, aims to synthesize ZnMo polynuclear clusters with conjugated structures. The synthesis is achieved via a hydrothermal method, yielding ZnMo polynuclear cluster photothermal materials with conjugated structures. This method utilizes a chemical hydrothermal approach, increasing the reaction rate during MOF preparation, constructing a conjugated system within polyacid clusters, significantly enhancing the light absorption rate of the target material, and greatly optimizing its evaporation performance. Finally, through vacuum filtration film-forming, ZnMo polynuclear cluster photothermal materials with conjugated structures are obtained.

[0029] The principle of synthesis in this step: A simple method was used to obtain ZnMo polynuclear clusters with conjugated ligands. The ZnMo polynuclear cluster structure has efficient light absorption and good photothermal conversion performance, which can efficiently convert the received solar energy into heat energy and promote the evaporation rate of water molecules. Mo element usually has good light absorption properties, while Zn-based materials also show good properties in optoelectronics. Therefore, this combination is beneficial to improving the overall photothermal conversion efficiency and self-healing performance.

[0030] This invention employs a simple and controllable method to induce coordination reactions between metal ions and these conjugated organic ligands. Due to the varying degrees of conjugation of the ligands, different effects are produced on the electronic structure and optical properties of the clusters. For example, the high degree of conjugation of the o-phenanthroline ligand results in abundant delocalized electrons, and the clusters formed by its coordination with metal ions exhibit unique properties in terms of light absorption and charge transfer.

[0031] Example 1: Methods for preparing photothermal evaporators based on ZnMo multinuclear cluster photothermal materials with conjugated ligands, such as Figure 1 As shown, the steps are as follows: Step 1: In a dry, inert atmosphere glove box (Ar / N2), mix 0.381 g molybdic acid, 0.163 g zinc citrate dihydrate, and 0.092 g pyridine, seal the mixture in a 25 mL polytetrafluoroethylene-lined reactor, then inject 5.00 mL of anhydrous N,N-dimethylformamide (DMF, dehydrated by molecular sieve) into the reactor, seal the liner, and place the liner in an ultrasonic instrument for ultrasonic dispersion for 15 minutes (40 kHz) until a homogeneous and transparent solution is formed. Step 2: Place the reactor containing the mixed solution into an autoclave and react in a high-temperature oven at 160°C for 3 days. After the reaction, cool to room temperature, remove the reactor, and wash the crystals 3 times (2 mL each time) with cold N,N-dimethylformamide (DMF0°C) to remove surface-adsorbed impurities. Then, perform vacuum filtration to collect the blue-black blocky crystals, which is the crude product A. Step 3: The crude product A was loaded into a Soxhlet extractor and extracted by continuous reflux at 85°C for 48 hours using anhydrous N,N-dimethylformamide (DMF) as solvent to obtain deep blue lustrous crystals. The deep blue lustrous crystals were replaced with anhydrous ethanol three times and transferred to a vacuum drying oven and dried at 80°C for 12 hours to obtain blue-black crystals, i.e., product A. Step 4: Take product A and grind it in an agate mortar cooled by liquid nitrogen for 10 minutes, then grind it to the particle size in an inert atmosphere glove box (Ar) to obtain powder B. Step 5: Disperse 30 mg of powder B and 10 mg of polyvinylidene fluoride (PVDF) in 5 mL of DMF and stir for 1 h to prepare a homogeneous mixed solution. Use a vacuum filtration device to perform vacuum filtration on the homogeneous solution with a nylon membrane with a pore size of 220 nm. After filtration, place the obtained filtrate in a room temperature environment for drying treatment, and then cut the membrane into pieces with a diameter of 3 cm and assemble them into a photothermal evaporator.

[0032] Example 2: The method for preparing a photothermal evaporator based on ZnMo multinuclear cluster photothermal material with conjugated ligands includes the following steps: Step 1: In a dry, inert atmosphere glove box (Ar / N2), mix 0.268 g molybdic acid, 0.251 g zinc citrate dihydrate, and 0.183 g 2,2-bipyridine, seal the mixture in a 25 mL polytetrafluoroethylene-lined reactor, then inject 5.00 mL of anhydrous N,N-dimethylformamide (DMF, dehydrated by molecular sieve) into the reactor, seal the liner, and place the liner in an ultrasonic apparatus for ultrasonic dispersion for 13 minutes (40 kHz) until a homogeneous and transparent solution is formed. Step 2: Place the reactor containing the mixed solution into an autoclave and react in a high-temperature oven at 150°C for 3 days. After the reaction, cool to room temperature, remove the reactor, and wash the crystals 3 times (2 mL each time) with cold N,N-dimethylformamide (DMF0°C) to remove surface-adsorbed impurities. Then, perform vacuum filtration to collect the blue-black blocky crystals, which is the crude product A. Step 3: The crude product A was loaded into a Soxhlet extractor and extracted by continuous reflux at 85°C for 48 hours using anhydrous N,N-dimethylformamide (DMF) as solvent to obtain deep blue lustrous crystals. The deep blue lustrous crystals were replaced with anhydrous ethanol three times and transferred to a vacuum drying oven and dried at 60°C for 12 hours to obtain blue-black crystals, i.e., product A. Step 4: Take product A and grind it in an agate mortar cooled by liquid nitrogen for 15 minutes, then grind it to the particle size in an inert atmosphere glove box (Ar) to obtain powder B. Step 5: Disperse 20 mg of powder B and 7 mg of polyvinylidene fluoride (PVDF) in 5 mL of DMF and stir for 1 h to prepare a homogeneous mixed solution. Use a vacuum filtration device to perform vacuum filtration on the homogeneous solution with a nylon membrane with a pore size of 220 nm. After filtration, place the obtained filtrate in a room temperature environment for drying treatment, and then cut the membrane into pieces with a diameter of 3 cm and assemble them into a photothermal evaporator.

[0033] Example 3: The method for preparing a photothermal evaporator based on ZnMo multinuclear cluster photothermal materials with conjugated ligands includes the following steps: Step 1: In a dry, inert atmosphere glove box (Ar / N2), mix 0.369 g molybdic acid, 0.245 g zinc citrate dihydrate, and 0.211 g 1,10-o-phenanthroline, seal the mixture in a 25 mL polytetrafluoroethylene-lined reactor, then inject 5.00 mL of anhydrous N,N-dimethylformamide (DMF, dehydrated by molecular sieve) into the reactor, seal the liner, and sonicate the liner in an ultrasonic instrument for 15 minutes (40 kHz) until a homogeneous and transparent solution is formed. Step 2: Place the reactor containing the mixed solution into an autoclave and react in a high-temperature oven at 155°C for 3 days. After the reaction, cool to room temperature, remove the reactor, and wash the crystals 3 times (2 mL each time) with cold N,N-dimethylformamide (DMF0°C) to remove surface-adsorbed impurities. Then, perform vacuum filtration to collect the blue-black blocky crystals, which is crude product A. Step 3: The crude product A was loaded into a Soxhlet extractor and extracted by continuous reflux at 85°C for 48 hours using anhydrous N,N-dimethylformamide (DMF) as solvent to obtain deep blue lustrous crystals. The deep blue lustrous crystals were replaced with anhydrous ethanol three times and transferred to a vacuum drying oven and dried at 75°C for 12 hours to obtain blue-black crystals, i.e., product A. Step 4: Take product A and grind it in an agate mortar cooled by liquid nitrogen for 18 minutes, then grind it to the particle size in an inert atmosphere glove box (Ar) to obtain powder B. Step 5: Disperse 25 mg of powder B and 7 mg of PVDF in 5 mL of DMF and stir for 1 h to prepare a homogeneous mixed solution. Use a vacuum filtration device to perform vacuum filtration on the homogeneous solution with a nylon membrane with a pore size of 220 nm. After filtration, place the obtained filtrate in a room temperature environment for drying treatment, and then cut the membrane into pieces with a diameter of 3 cm and assemble them into a photothermal evaporator.

[0034] Example 4: The method for preparing a photothermal evaporator based on ZnMo multinuclear cluster photothermal materials with conjugated ligands includes the following steps: Step 1: In a dry, inert atmosphere glove box (Ar / N2), mix 0.394 g molybdic acid, 0.197 g zinc citrate dihydrate, and 0.211 g 1,10-o-phenanthroline, seal the mixture in a 25 mL polytetrafluoroethylene-lined reactor, then inject 5.00 mL of anhydrous N,N-dimethylformamide (DMF, dehydrated by molecular sieve) into the reactor, seal the liner, and sonicate the liner in an ultrasonic instrument for 15 minutes (40 kHz) until a homogeneous and transparent solution is formed. Step 2: Place the reactor containing the mixed solution into an autoclave and react in a high-temperature oven at 140°C for 3 days. After the reaction, cool to room temperature, remove the reactor, and wash the crystals 3 times (2 mL each time) with cold N,N-dimethylformamide (DMF0°C) to remove surface-adsorbed impurities. Then, perform vacuum filtration to collect the blue-black blocky crystals, which is the crude product A. Step 3: The crude product A was loaded into a Soxhlet extractor and extracted by continuous reflux at 85°C for 48 hours using anhydrous N,N-dimethylformamide (DMF) as solvent to obtain deep blue lustrous crystals. The deep blue lustrous crystals were replaced with anhydrous ethanol three times and transferred to a vacuum drying oven and dried at 80°C for 12 hours to obtain blue-black crystals, i.e., product A. Step 4: Take product A and grind it in an agate mortar cooled by liquid nitrogen for 12 minutes, then grind it to the particle size in an inert atmosphere glove box (Ar) to obtain powder B. Step 5: Disperse 20 mg of powder B and 6 mg of PVDF in 5 mL of polyvinylidene fluoride (PVDF) and stir for 1 h to prepare a homogeneous mixed solution. Use a vacuum filtration device to perform vacuum filtration on the homogeneous solution with a nylon membrane with a pore size of 220 nm. After filtration, place the obtained filtrate in a room temperature environment for drying treatment, and then cut the membrane into pieces with a diameter of 3 cm and assemble them into a photothermal evaporator.

[0035] Example 5: The method for preparing a photothermal evaporator based on ZnMo multinuclear cluster photothermal material with conjugated ligands includes the following steps: Step 1: In a dry, inert atmosphere glove box (Ar / N2), mix 0.357 g molybdic acid, 0.159 g zinc citrate dihydrate, and 0.211 g 1,10-o-phenanthroline, seal the mixture in a 25 mL polytetrafluoroethylene-lined reactor, then inject 5.00 mL of anhydrous N,N-dimethylformamide (DMF, dehydrated by molecular sieve) into the reactor, seal the liner, and place the liner in an ultrasonic instrument for ultrasonic dispersion for 15 minutes (40 kHz) until a homogeneous and transparent solution is formed. Step 2: Place the reactor containing the mixed solution into an autoclave and react in a high-temperature oven at 170°C for 3 days. After the reaction, cool to room temperature, remove the reactor, and wash the crystals 3 times (2 mL each time) with cold N,N-dimethylformamide (DMF0°C) to remove surface-adsorbed impurities. Then, perform vacuum filtration to collect the blue-black blocky crystals, which is the crude product A. Step 3: The crude product A was loaded into a Soxhlet extractor and extracted by continuous reflux at 85°C for 48 hours using anhydrous N,N-dimethylformamide (DMF) as solvent to obtain deep blue lustrous crystals. The deep blue lustrous crystals were replaced with anhydrous ethanol three times and transferred to a vacuum drying oven and dried at 68°C for 12 hours to obtain blue-black crystals, i.e., product A. Step 4: Take product A and grind it in an agate mortar cooled by liquid nitrogen for 17 minutes, then grind it to the particle size in an inert atmosphere glove box (Ar) to obtain powder B. Step 5: Disperse 35mg of powder B and 13mg of PVDF in 5 mL of polyvinylidene fluoride (PVDF) and stir for 1 hour to prepare a homogeneous mixed solution. Use a vacuum filtration device to perform vacuum filtration on the homogeneous solution with a nylon membrane with a pore size of 220nm. After filtration, place the obtained filtrate in a room temperature environment for drying treatment, and then cut the membrane into pieces with a diameter of 3 cm and assemble them into a photothermal evaporator.

[0036] The above-described embodiment 1 is the preferred embodiment of the present invention.

[0037] Figure 2 shows the infrared spectra of the three ZnMo polynuclear clusters of this invention. All three compounds exhibit significant absorption between 3000 and 3700 cm⁻¹, indicating the presence of abundant free and bound water. Absorption is less than 1700 cm⁻¹. -1 The absorption is due to the characteristic vibrations of the Mo-O and Zn-O chemical bonds.

[0038] like Figure 3 The figure shows a comparison of mass loss among the three ZnMo multinuclear clusters of this invention under one solar radiation intensity. With increasing conjugation, the change in mass also increases significantly, with the o-phenanthroline cluster showing the most prominent change, exhibiting a superior water evaporation capacity.

[0039] like Figure 4 The figure shows a comparison of the evaporation rates and evaporation efficiencies of all samples of the three ZnMo polynuclear clusters under one solar irradiation. Specifically, the evaporation rates of the o-phenanthroline cluster, the 2,2-bipyridine cluster, and the pyridine cluster under one solar irradiation were 1.25, 1.12, and 0.96 kg m³, respectively. −2 h −1 Its evaporation rate gradually decreases, which corresponds to its temperature change trend and light absorption capacity. Compared with pure water 0.43 kg m −2 h −1 Compared to the evaporation rate of [previous method], the improvement is extremely significant. To further evaluate the photothermal conversion performance, the solar evaporation efficiency was calculated. It can be seen that with the increase of conjugation degree, the evaporation efficiency also increases significantly. Among them, the evaporation efficiency of the o-phenanthroline cluster can reach more than 85%, demonstrating a super strong water evaporation capacity.

[0040] like Figure 5 As shown, the ZnMo multinuclear clusters of this invention were tested for their resistance to photobleaching in 10 light-on / off cycles on different powder samples. Ten experimental cycles were conducted on three samples under the same irradiation conditions to verify their cycle stability. As shown in the figure, after 10 irradiations, the temperature remained almost unchanged. The target sample, the o-phenanthroline cluster, remained stable at 80 °C, the bipyridine cluster remained stable at 70 °C, and the pyridine cluster remained stable at 65 °C. This result indicates that during the ten light-irradiation cycles, the temperature of all three samples maintained a stable heating rate and reached the maximum temperature, demonstrating excellent stability in the light-irradiation cycle test.

[0041] like Figure 6 As shown, the ZnMo multinuclear cluster of the present invention is at 0.1 W / cm². 2 The photothermal conversion behavior of o-phenanthroline cluster powder under xenon lamp irradiation for 1200 seconds was studied, with an energy power of 0.1 W / cm². 2The material was irradiated with a xenon lamp light source. In the experiment, the temperature slowly increased from 23.5 °C to about 80 °C within 150 s, and rapidly dropped to room temperature within 100 s after the light source was removed, indicating that the material has a rapid photothermal conversion response.

[0042] This invention employs a simple and green chemical hydrothermal method to prepare ZnMo polyacid clusters, which are then blended with conjugated ligands to form a unique conjugated π-bond system. The resulting sample exhibits high light absorption capacity, an ordered crystal structure, ultralight weight, low cost, and high performance. Its multiple active sites provide abundant pathways for sunlight absorption. During photothermal conversion, adsorbed water molecules act as a heat transfer medium, rapidly absorbing and carrying away heat through interaction with the polyacid cluster surface, achieving a highly efficient water evaporation process and yielding an ideal photothermal conversion material.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for preparing a photothermal evaporator based on ZnMo multinuclear cluster photothermal material with conjugated ligands, characterized in that, Step 1: In a dry, inert atmosphere glove box, mix 0.2–0.4 g of molybdic acid, 0.1–0.3 g of zinc citrate dihydrate and 0.05–0.3 g of polypyridine compound, seal the mixture in a 25 mL polytetrafluoroethylene-lined reactor, then inject 5.00 mL of anhydrous N,N-dimethylformamide into the reactor, seal the liner, place the liner in an ultrasonic instrument, and ultrasonically disperse the mixture at 40 kHz for 10–15 minutes until a homogeneous and transparent solution is formed. Step 2: Place the reactor containing the mixed solution into an autoclave and react in a high-temperature oven for 3 days. After the reaction, cool to room temperature, remove the reactor, and wash the crystals three times with N,N-dimethylformamide at 0°C to remove impurities adsorbed on the surface. Then, perform vacuum filtration to collect the blue-black blocky crystals, which is the crude product A. Step 3: The crude product A is loaded into a Soxhlet extractor and extracted by continuous reflux at 75-95°C for 48 hours using anhydrous N,N-dimethylformamide as solvent to obtain dark blue lustrous crystals. The dark blue lustrous crystals are replaced with anhydrous ethanol three times and transferred to a vacuum drying oven for drying for 12 hours to obtain blue-black crystals, i.e., product A. Step 4: Take product A in an agate mortar cooled by liquid nitrogen and grind it to the particle size in an inert atmosphere glove box to obtain powder B; Step 5: Disperse 20-40 mg of powder B and 5-14 mg of polyvinylidene fluoride in 5 mL of N,N-dimethylformamide and stir for 1 h to prepare a homogeneous mixed solution. Use a vacuum filtration device to filter the homogeneous solution with a nylon membrane with a pore size of 220 nm. After filtration, place the obtained filtrate in a room temperature environment for drying. Then cut the membrane into pieces with a diameter of 3 cm and assemble them into a photothermal evaporator.

2. The method for preparing a photothermal evaporator based on ZnMo multinuclear cluster photothermal material with conjugated ligands according to claim 1, characterized in that, In step 1), the polypyridine compound is 1,10-phenanthroline, pyridine, or 2,2-bipyridine.

3. The method for preparing a photothermal evaporator based on ZnMo multinuclear cluster photothermal material with conjugated ligands according to claim 1 or 2, characterized in that, The temperature of the high-temperature oven in step 2) is 140-160℃.

4. The method for preparing a photothermal evaporator based on ZnMo multinuclear cluster photothermal material with conjugated ligands according to claim 3, characterized in that, The temperature of the vacuum drying oven in step 3) is 60-80℃.

5. The method for preparing a photothermal evaporator based on ZnMo multinuclear cluster photothermal material with conjugated ligands according to claim 4, characterized in that, The grinding time in the mortar in step 4) is 10-20 minutes.

Images