Alkaline lignin supported copper sulfide nanoparticles, photothermal electric device and preparation method and application thereof

Abstract

The application belongs to the technical field of photothermal-electric conversion, and particularly relates to alkali lignin loaded copper sulfide nanoparticles, a photothermal-electric device and a preparation method and application thereof. 2+ After adsorption, S 2‑ reacts to prepare alkali lignin loaded copper sulfide nanoparticles, and the alkali lignin loaded copper sulfide nanoparticles are assembled with hydrogel having a thermoelectric function to obtain a photothermal-electric device. The alkali lignin loaded copper sulfide nanoparticles have excellent photothermal conversion efficiency and long-term stability as a photothermal conversion material, and are the key to performance improvement of the photothermal-electric device. The hydrogel having the thermoelectric function maintains excellent thermoelectric performance and water retention performance, and enhances the stability and durability of the hydrogel. The photothermal-electric device assembled by the two has not only excellent photothermal-electric performance, but also a long service life, which fully proves the great potential and application prospect of the alkali lignin loaded copper sulfide nanoparticles in the field of photothermal-electric devices.

Description

Technical Field

[0001] The present invention belongs to the field of photothermoelectric conversion technology. More specifically, it relates to an alkali lignin-loaded copper sulfide nanoparticle, a photothermoelectric device, and its preparation method and application. Background Art

[0002] Against the backdrop of growing global energy demand and increasingly severe environmental challenges, research in energy conversion technologies has become a pressing scientific issue. Photothermal-to-electricity conversion, as an innovative and environmentally friendly new energy conversion method, demonstrates unprecedented potential in the exploration of renewable resources. This technology not only captures energy from the living environment, industrial processes, solar radiation, and low-grade thermal energy (temperatures below 100°C), but also synergistically converts the captured light and thermal energy into electricity, significantly expanding the boundaries of energy utilization.

[0003] The core advantage of photothermal-electric conversion technology lies in its unique dual mechanism of photothermal conversion and thermoelectric conversion, in which photothermal conversion converts light energy into thermal energy, while thermoelectric conversion further converts thermal energy into electrical energy, thereby realizing the conversion of light energy into electrical energy. However, most current photothermal-electric conversion technologies mainly use visible light and some ultraviolet light for photothermal conversion, and the utilization of the important near-infrared light band is still insufficient, so the performance of the prepared photothermal electric devices has not reached the expected level. Therefore, the development of photothermal conversion materials with near-infrared absorption is an inevitable choice. Such materials can broaden the spectral response range, improve the photothermal conversion efficiency to achieve better photoelectric conversion, and complete more efficient electrical energy output, thereby achieving the purpose of significantly improving the photothermal-electric performance of the prepared photothermal electric devices. For example, Xie Yuanxiang et al. (Xie Y, Qian Y, Li Z, et al. Near-infrared-activated efficient bacteria-killing bylignin-based copper sulfide nanocomposites with an enhanced photothermal effect and peroxidase-like activity [J]. ACS Sustainable Chemistry & Engineering, 2021, 9(18): 6479-6488.) synthesized a lignin-copper sulfide nanocomposite using lignin sulfonate as a growth template and stabilizer. The material exhibited enhanced photothermal performance under near-infrared light activation. When irradiated with near-infrared light (800 nm, 1.8 W / cm²), the temperature increased from 26.3 ℃ to 56.0 ℃. However, despite showing certain application potential, its photothermal conversion efficiency is still low and needs to be further improved. Summary of the Invention

[0004] The present invention aims to solve the problem of low photothermal conversion efficiency of photothermal conversion materials in the prior art within a wide spectral response range, as well as the huge challenges faced in applying them in photothermal electric conversion devices. It provides an alkali lignin-loaded copper sulfide nanoparticle, a photothermal electric device, and a preparation method and application thereof.

[0005] Specifically, one of the objectives of the present invention is to provide a method for preparing alkali lignin-loaded copper sulfide nanoparticles.

[0006] Another object of the present invention is to provide alkali lignin-loaded copper sulfide nanoparticles prepared by the above preparation method.

[0007] Another object of the present invention is to provide a photothermoelectric device.

[0008] Another object of the present invention is to provide applications of the above-mentioned alkali lignin-loaded copper sulfide nanoparticles or the above-mentioned photothermoelectric devices in the fields of photothermoelectric conversion and wearable devices.

[0009] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0010] The present invention provides a method for preparing alkali lignin-loaded copper sulfide nanoparticles, comprising the following steps:

[0011] The alkali lignin nanoparticles and copper salt solution were fully mixed and centrifuged, and the precipitate was mixed with the S-containing 2- The ion solution is fully mixed and then centrifuged, and the precipitate is dried to obtain alkali lignin-loaded copper sulfide nanoparticles.

[0012] Alkali lignin is rich in aromatic rings and hydroxyl groups, which can not only absorb visible light and near-infrared light, realize photothermal conversion, but also improve the dispersion and stability of the material; the high light absorption capacity of copper sulfide enables it to effectively absorb visible light and near-infrared light. The present invention innovatively prepares alkali lignin into nanoparticles and then absorbs Cu in copper salt. 2+ Then with S 2- The alkali lignin-loaded copper sulfide nanoparticles were prepared by reaction. The stepwise reaction strategy adopted in the above preparation method effectively avoided the aggregation of particles. The obtained alkali lignin-loaded copper sulfide nanoparticles had a small particle size (which also means a large specific surface area) and good dispersibility. This preparation method is conducive to promoting the alkali lignin nanoparticles to Cu 2+ Highly efficient adsorption, ensuring that 2- During the reaction, a uniform copper sulfide structure is formed, thereby improving the light-to-heat conversion efficiency and long-term stability of the resulting alkali lignin-supported copper sulfide nanoparticles. Furthermore, the alkali lignin-supported copper sulfide nanoparticles prepared using this method have a large specific surface area, which further enhances the interaction between the alkali lignin-supported copper sulfide nanoparticles and light and improves their thermal conductivity.

[0013] Furthermore, the preparation method of the alkali lignin nanoparticles comprises the following steps:

[0014] The alkali lignin is fully dissolved in a solvent and then centrifuged. The supernatant is mixed with water to prepare a suspension, which is then centrifuged. The precipitate is the alkali lignin nanoparticles.

[0015] Furthermore, the solvent includes one or more of γ-valerolactone aqueous solution, methanol, ethanol, isopropanol, acetone, sodium hydroxide, dimethylsulfamide, dimethylformamide, and acetic acid.

[0016] Preferably, the solvent is a γ-valerolactone aqueous solution, which can better dissolve alkali lignin and improve its utilization rate.

[0017] More preferably, the volume ratio of the γ-valerolactone and water is 1: (0.1~0.2).

[0018] Further, the mass ratio of the alkali lignin and solvent is 1: (50~150).

[0019] Further, the mixing is ultrasonic mixing.

[0020] Further, the ultrasonic time is 30~60 min.

[0021] Further, the centrifugal rate after the sufficient dissolution is 1000~2000 g. Wherein, g represents the acceleration of gravity.

[0022] Further, the centrifugal time after the sufficient dissolution is 15~30 min.

[0023] Further, the centrifugal rate of the suspension is 8000~12000 g.

[0024] Further, the centrifugal time of the suspension is 30~60 min.

[0025] Preferably, the copper salt includes one or more of copper sulfate, copper chloride, copper acetate.

[0026] Further, the mixing ratio of the alkali lignin nanoparticles and copper salt is 1: (0.0004~0.004) g / mol.

[0027] Further, the mixing is stirring.

[0028] Further, the stirring time is 12~24 h.

[0029] Further, the centrifugal rate is 8000~10000 r / min.

[0030] Preferably, the centrifugal time is 15~30 min.

[0031] Further, the S 2- The ion is selected from one or more of sodium sulfide nonahydrate, hydrogen sulfide, sodium thiosulfate.

[0032] Further, the precipitate, S 2- The mixing ratio of the ion is 1: (0.0004~0.002) g / mol.

[0033] Further, the drying is freeze-drying the precipitate for 1~3 days.

[0034] The present invention protects alkali lignin-loaded copper sulfide nanoparticles prepared by the above preparation method.

[0035] The present invention protects a photothermoelectric device, which is mainly composed of a photothermal conversion material and a thermoelectric conversion device, wherein the photothermal conversion material and the thermoelectric conversion device are electrically connected through electrodes in the thermoelectric conversion device; the photothermal conversion material is the above-mentioned alkali lignin-loaded copper sulfide nanoparticles.

[0036] The operating principle of these photothermoelectric devices is based on a combination of the photothermal and thermoelectric effects. When exposed to light, the photothermal conversion material within the device converts light energy into heat, resulting in a temperature difference across the device. This temperature difference drives the migration of cations and anions within the thermoelectric device, which then converge on the two electrodes within the device, generating a potential difference or current. By measuring this potential difference or current, the detection and measurement of light radiation can be achieved.

[0037] The present invention combines the prepared photothermal conversion material with a thermoelectric conversion device to prepare an all-weather solar thermoelectric device with excellent performance, showing great potential in the basic research and practical application of self-powered wearable devices.

[0038] Furthermore, the thermoelectric conversion device includes a stacked structure arranged in sequence: a first electrode, a thermoelectric conversion material, and a second electrode.

[0039] Furthermore, the light-to-heat conversion material is disposed on the surface of the first electrode.

[0040] Specifically, the photothermoelectric device includes a stacked structure arranged in sequence: a photothermal conversion material, a first electrode, a thermoelectric conversion material, and a second electrode. When the photothermal conversion material is placed upward under a light source, photothermal-electrical conversion can be effectively achieved.

[0041] Furthermore, the thermoelectric conversion material is a hydrogel with thermoelectric function.

[0042] Preferably, as a preferred embodiment, the hydrogel having thermoelectric function is obtained by the following preparation method, which comprises the following steps:

[0043] Cyclodextrin-modified lignin sulfonate and adamantyl acrylate are added to a solvent containing thermoelectric materials and mixed evenly, and unsaturated carboxylic acid monomers, acrylamide monomers, metal ions and initiators are added and reacted fully to prepare a hydrogel with thermoelectric function;

[0044] Furthermore, the preparation method of the cyclodextrin-modified lignin sulfonate comprises the following steps:

[0045] SI. Mix cyclodextrin, p-toluenesulfonylimidazole and alkaline reagent in water, filter, adjust the pH of the filtrate to 7-8, fully react, and then treat to obtain intermediate product CDOTs;

[0046] SII. Mix CDOTs obtained in step SI and lignosulfonate in water, fully react at 70-80 ℃, and then treat to obtain cyclodextrin-modified lignosulfonate.

[0047] Further, in step SI, the cyclodextrin includes one or more of α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin. Cyclodextrin-modified lignosulfonate obtained from cyclodextrins with different crystal structures can all prepare thermoelectric hydrogel with good performance. Among them, the inner diameter of β-cyclodextrin is moderate, which is more suitable for inclusion of hydrophobic molecules (such as adamantane), thereby improving the solubility and stability thereof, and is conducive to subsequent construction of a structure-stable hydrogel. Therefore, the cyclodextrin is preferably β-cyclodextrin.

[0048] Further, in step SI, the mass ratio of the cyclodextrin to p-toluenesulfonylimidazole is (1.5-10):(1-3).

[0049] Further, in step SI, the mass ratio of the cyclodextrin to p-toluenesulfonylimidazole is (1.5-10):1.

[0050] Further, in step SI, the mixing is stirring mixing.

[0051] Further, the stirring time is 2-4 h.

[0052] Further, in step SI, the pH adjustment is adjustment using hydrochloric acid.

[0053] Further, in step SI, the precipitation time is 18-36 h.

[0054] Further, in step SI, the post-treatment includes filtration, washing and recrystallization.

[0055] Further, the filtration is filtration of the precipitated substance to collect the filter residue.

[0056] Further, the washing is washing of the collected filter residue with ice water and acetone for 3-5 times in sequence.

[0057] Further, the recrystallization is recrystallization of the washed filter residue with hot water at 80-100 ℃ to remove soluble impurities, which is repeated for 2-3 times.

[0058] Specifically, in step SI, the post-treatment includes filtering the precipitated material, collecting the filter residue, washing the filter residue with ice water and acetone 3 to 5 times in sequence, collecting the washed filter residue and then recrystallizing it with hot water at 80 to 100°C to remove soluble impurities, repeating 2 to 3 times, and the product obtained after recrystallization is the intermediate product CDOTs.

[0059] Furthermore, in step SII, the mass ratio of the CDOTs to the alkali lignin sulfonate is 1:(0.67-2.5).

[0060] Furthermore, in step SII, the mixing time is 1 to 2 hours.

[0061] Furthermore, in step SII, the sufficient reaction time is 48 to 72 hours.

[0062] Furthermore, in step SII, the post-treatment includes dialysis and drying.

[0063] Furthermore, the dialysis is to dialyze the cooled mixture and collect the retained fluid.

[0064] Furthermore, the drying is to dry the retained solution after dialysis, and the drying is preferably freeze drying.

[0065] Specifically, in step SII, the post-treatment includes dialyzing the cooled mixture, and freeze-drying the retained solution after the dialysis to obtain cyclodextrin-modified lignin sulfonate.

[0066] Furthermore, as a preferred embodiment, the preparation method of adamantyl acrylate comprises the following steps:

[0067] Si. Adamantane alcohol and triethylamine were added to an organic solvent and mixed to obtain a mixed solution;

[0068] Sii. Dilute acryloyl chloride with an organic solvent and add it dropwise to the mixed solution obtained in step Si, mix well, and then post-treat to obtain adamantyl acrylate.

[0069] Furthermore, in step Si, the adamantane alcohol is 1-adamantanol and / or 2-adamantanol.

[0070] Preferably, the adamantane alcohol is 1-adamantanol, which has stronger reactivity and is more likely to undergo nucleophilic substitution reaction with acryloyl chloride to form corresponding esters or amino compounds.

[0071] Furthermore, in step Si, the mass ratio of adamantane alcohol to triethylamine is 1:(1-3).

[0072] Furthermore, in step S1, the mixing time is 15 to 40 minutes.

[0073] Furthermore, in step Sii, the mass ratio of the acryloyl chloride to the organic solvent is 1:(1.67-10).

[0074] Furthermore, in step Sii, the mixing time is 18 to 36 hours.

[0075] Furthermore, in step Sii, the post-treatment includes filtration, washing, concentration, and purification.

[0076] Furthermore, the filtration is to filter the mixed solution and collect the filtrate.

[0077] Furthermore, the washing step is to wash the filtrate with ice water and acetone in sequence for 1 to 3 times.

[0078] Furthermore, the concentration is to collect the organic phase after washing and concentrate it by rotary evaporation at low temperature and reduced pressure at 4-15°C.

[0079] Furthermore, the purification is to purify the concentrated material using column chromatography, and the eluent is V 乙酸乙酯 :V 正己烷 =1:(15~20).

[0080] Specifically, in step Sii, the post-treatment includes filtering the mixed solution, collecting the filtrate, washing the filtrate with ice water and acetone 1 to 3 times in sequence, collecting the washed organic phase and concentrating it by rotary evaporation at a low temperature of 4 to 15 ° C under reduced pressure, and purifying the concentrated substance by column chromatography, and the eluent is V 乙酸乙酯 :V 正己烷 =1:(15~20).

[0081] Furthermore, the mass ratio of the cyclodextrin-modified lignin sulfonate to adamantyl acrylate is (1-75):1. The cyclodextrin-modified lignin sulfonate serves as a catalyst and physical crosslinker, while the adamantyl acrylate serves as a chemical crosslinker for the network structure. At this mass ratio, the crosslinking density is more appropriate, and the resulting material exhibits superior mechanical properties.

[0082] Furthermore, the mass ratio of the cyclodextrin modified lignin sulfonate to adamantyl acrylate is (1-40):1.

[0083] Preferably, the mass ratio of the cyclodextrin-modified lignin sulfonate to adamantyl acrylate is 1:0.18.

[0084] Preferably, the thermoelectric material comprises one or more of lithium chloride, sodium chloride, and potassium chloride. These thermoelectric materials can enhance interactions between polymer chains (such as ionic bonds and hydrogen bonds), maintain the stability of the network structure, and improve the mechanical strength of the hydrogel.

[0085] Furthermore, the thermoelectric material is lithium chloride. Lithium chloride exhibits excellent thermoelectric performance, specifically a high thermoelectric figure of merit (i.e., ZT, ZT = σS²T / κ, where σ is electrical conductivity, S is the Seebeck coefficient, T is temperature, and κ is thermal conductivity) and good thermal stability. In addition, it is low-cost and readily available, so lithium chloride is preferably used as the thermoelectric material.

[0086] Furthermore, the concentration of the thermoelectric material is 0.1-3 mol / L.

[0087] Furthermore, the solvent is water or a moisturizing agent aqueous solution.

[0088] Furthermore, the moisturizing agent is glycerin and / or propylene glycol.

[0089] Preferably, the solvent is a moisturizing aqueous solution. Adding a moisturizing agent to the hydrogel can effectively enhance its moisturizing properties and slow down water loss, thereby improving the stability and efficiency of the photothermoelectric device.

[0090] More preferably, the moisturizing agent aqueous solution contains 甘油 :V 水 =1: (1~5).

[0091] Furthermore, the mixing time is 30 to 60 minutes.

[0092] Furthermore, the unsaturated carboxylic acid monomer is C3-C8 olefinic acid and / or C3-C8 acetylenic acid.

[0093] Furthermore, the unsaturated carboxylic acid monomer is C3-C5 olefinic acid and / or C3-C5 acetylenic acid.

[0094] Furthermore, the unsaturated carboxylic acid monomer includes one or more of acrylic acid, methacrylic acid, crotonic acid, propiolic acid, and butynic acid.

[0095] Furthermore, the acrylamide monomers include one or more of acrylamide, methacrylamide, and ethyl acrylamide.

[0096] Furthermore, the mass ratio of the unsaturated carboxylic acid monomer to the acrylamide monomer is 1:(0.8-1.5).

[0097] Furthermore, the metal ions are derived from one or more of stannous chloride, ferric chloride, calcium chloride, barium chloride, aluminum chloride, cobalt chloride, nickel chloride, copper chloride, and silver chloride.

[0098] Preferably, the metal ion is stannous chloride. In the method for rapidly preparing multifunctional thermoelectric hydrogels using a metal-phenolic chemical system, the introduction of stannous ions not only makes the hydrogel more uniform but also significantly enhances its tensile properties compared to other transition metals (such as iron, cobalt, and nickel).

[0099] Furthermore, the initiator is ammonium persulfate and / or potassium persulfate.

[0100] Furthermore, the sufficient reaction is that the cyclodextrin-modified lignin and the metal ions form a redox coordination system that can activate the initiator and quickly prepare the hydrogel.

[0101] Furthermore, the electrode is a polyaniline carbon fiber cloth electrode.

[0102] Furthermore, the polyaniline carbon fiber cloth electrode is prepared by a chemical oxidation deposition method, and comprises polyaniline and carbon fiber cloth, wherein the polyaniline is coated on the surface of the carbon fiber cloth.

[0103] Furthermore, the preparation method of the polyaniline carbon fiber cloth electrode includes the following steps:

[0104] Aniline monomer and initiator were dissolved in acidic reagents respectively, and carbon fiber cloth was immersed in aniline solution. Then, the initiator solution was added to the aniline solution, and the reaction was fully carried out at low temperature. After post-treatment, polyaniline carbon fiber cloth electrode (PANI@CWF) was obtained.

[0105] Furthermore, the initiator is ammonium persulfate and / or potassium persulfate.

[0106] Furthermore, the molar ratio of the aniline monomer to the initiator is 1:(0.25~1).

[0107] Furthermore, the molar ratio of the aniline monomer to the initiator is 1:1.

[0108] Furthermore, the low temperature is an ice water bath.

[0109] Furthermore, the sufficient reaction time is 4 to 16 hours, preferably 12 hours.

[0110] Furthermore, the post-treatment includes washing and drying.

[0111] Furthermore, the washing is to rinse the carbon fiber cloth electrode containing polyaniline with deionized water 3 to 6 times.

[0112] Furthermore, the drying is annealing in a vacuum oven at 60-80° C. for 2-4 h.

[0113] Specifically, the post-treatment includes rinsing the carbon fiber cloth electrode containing polyaniline with deionized water three times, and then annealing it in a vacuum oven at 60-80° C. for 2-4 hours.

[0114] Furthermore, the photothermoelectric device further comprises a stabilizing member having a hollow portion, and the photothermal conversion material is disposed in the hollow portion of the stabilizing member and connected to the electrode.

[0115] Preferably, the stabilizing member is an adhesive tape, which has double-sided adhesiveness, insulation properties, and a certain thickness and can be used to prepare the stabilizing member.

[0116] Furthermore, the tape includes any one of polypropylene tape (VHB tape), polyurethane tape, acrylic tape, silicone tape, and polyester tape.

[0117] Preferably, the stabilizing member is a VHB tape. VHB tape has excellent adhesion, temperature resistance, aging resistance and good flexibility, and can provide good lamination effects on different substrate surfaces and adapt to various shapes and surfaces.

[0118] Furthermore, as a preferred embodiment, the method for preparing the photothermoelectric device comprises the following steps:

[0119] Two layers of 1.5 cm × 2.5 cm PANI@CWF electrodes were used to encapsulate the thermoelectric hydrogel in a cylindrical mold made of VHB tape (1.5 cm × 1.5 cm with a circular cavity 1.2 cm in diameter and 1.2 cm in height). This formed a "sandwich" thermoelectric conversion device, consisting of electrode, thermoelectric hydrogel, and electrode. Subsequently, another 1.5 cm × 1.5 cm piece of VHB tape was attached to the top electrode, also containing a circular cavity 1.2 cm in diameter. This cavity was filled with alkali lignin-loaded copper sulfide nanoparticles, resulting in a photothermoelectric conversion device.

[0120] The present invention also protects the application of the above-mentioned alkali lignin-loaded copper sulfide nanoparticles or the above-mentioned photothermoelectric device in the field of wearable devices.

[0121] Compared with the prior art, the present invention has the following beneficial effects:

[0122] The present invention innovatively firstly combines the alkali lignin nanoparticles and the Cu in the copper salt 2+ After adsorption with S 2-A kind of alkali lignin supported copper sulfide nanoparticles is prepared by reaction, and then a photothermal electric device is assembled with hydrogel with thermoelectric function, wherein the alkali lignin supported copper sulfide nanoparticles as photothermal conversion material has excellent photothermal conversion efficiency and long-term stability, which is the key to performance improvement of photothermal electric device; the hydrogel with thermoelectric function maintains excellent thermoelectric performance and water retention performance, and enhances the stability and durability of the hydrogel; the photothermal electric device assembled by the two not only has excellent thermoelectric performance, but also has a long service life, which fully proves the great potential and application prospect of alkali lignin supported copper sulfide nanoparticles in the field of photothermal electric device. BRIEF DESCRIPTION OF DRAWINGS

[0123] Figure 1 Structure diagram of photothermal electric device prepared in Example 1.

[0124] Figure 2 Infrared spectrum diagram of alkali lignin supported copper sulfide nanoparticles prepared in Example 1.

[0125] Figure 3 SEM image of alkali lignin supported copper sulfide nanoparticles prepared in Example 1.

[0126] Figure 4 SEM image of alkali lignin supported copper sulfide nanoparticles prepared in Comparative Example 1.

[0127] Figure 5 Temperature change diagram of photothermal conversion material prepared in Example 1, Comparative Example 1 and Comparative Example 2 under different time simulated solar radiation.

[0128] Figure 6 Temperature change curve diagram of alkali lignin supported copper sulfide nanoparticles prepared in Example 1 under different light power (a), relationship curve diagram between temperature change and light power density under different solar radiation intensity (b), and reversible temperature change diagram under simulated solar radiation (100 mW / cm²) (c).

[0129] Figure 7 Mass change curve diagram (a) and anti-freezing optical diagram (b) of thermoelectric hydrogel prepared in Example 1.

[0130] Figure 8 Open-circuit voltage-time curve diagram (a), power-time curve diagram (b) and output voltage stability diagram (c) of photothermal electric conversion device prepared in Example 1. DETAILED DESCRIPTION

[0131] The present invention will be further described below with reference to the accompanying drawings and specific examples, but the examples do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0132] Unless otherwise specified, the reagents and materials used in the following examples were commercially available.

[0133] Alkali lignin was provided by Shanghai Changfa New Materials Co., Ltd.

[0134] Figure 6 a means Figure 6 Figure a in Figure 6 b means Figure 6 The naming of other figures is similar to Figure b in .

[0135] Example 1 Alkali lignin-loaded copper sulfide nanoparticles, thermoelectric functional hydrogel, photothermoelectric conversion device, and preparation method thereof

[0136] 1. Preparation of Alkali Lignin-Loaded Copper Sulfide Nanoparticles (AL-NPs@CuS-1)

[0137] At room temperature (25 °C), 200 mg of alkali lignin (AL) was added to 20 mL of γ-valerolactone / water system solution (GVL / H2O), where V GLY :V H2O =87:13. Subsequently, sonication was performed for 30 minutes to ensure complete dissolution of the alkali lignin. This was followed by centrifugation at 2000 g for 30 minutes, resulting in a saturated alkali lignin solution as the supernatant. This solution was rapidly poured into water to form a 200 mL suspension. Subsequently, centrifugation was performed at 10,000 g for 30 minutes to precipitate alkali lignin nanoparticles (AL-NPs). The precipitated AL-NPs were dispersed in 200 mL of ultrapure water, and 3.9 g of copper sulfate pentahydrate (CuSO4·5H2O) was added. The mixture was stirred at room temperature for 12 hours. The mixture was then centrifuged at 8000 r / min for 15 minutes, the supernatant removed, and the precipitate retained. The resulting precipitate was dispersed in 100 mL of deionized water, 100 mg of sodium sulfide nonahydrate (Na2S·9H2O) was added, and the mixture was stirred in a 60°C water bath for 5 hours. The mixture was centrifuged again at 8000 r / min for 15 minutes, the supernatant removed, and the precipitate retained. Finally, the precipitate was freeze-dried in vacuum for 2 days to obtain AL-NPS@CuS-1.

[0138] 2. Preparation of Cyclodextrin-modified Lignin Sulfonate (LS-CD)

[0139] 36.3 g of β-cyclodextrin and 6.67 g of 1-p-toluenesulfonyl imidazole were added to 250 mL of deionized water and stirred vigorously at room temperature for 3 h. After adding 50 mL of 10 wt% NaOH solution, stirring was continued for 30 min. Unreacted insoluble matter was removed by filtration, and then 1 M HCl solution was added to adjust the pH of the filtrate to 7.5. The resulting mixture was precipitated at low temperature for 18 h, then filtered to collect the residue. The crude product was washed three times with ice water and acetone, respectively, to obtain the crude product. The crude product was recrystallized three times from hot water to obtain the product CDOTs. 6.5 g of lignin sulfonate was dissolved in 150 mL of deionized water and stirred vigorously to obtain a clear solution. 6.5 g of CDOTs was added, and the solution was stirred vigorously at room temperature for 2 h. The temperature was then raised to 80°C and refluxed for 72 h. After cooling, the solution was transferred to a MWC 3500 dialysis bag and dialyzed for 3 days. The retentate was freeze-dried to obtain a yellow or light yellow product, namely LS-CD.

[0140] 3. Preparation of Adamantyl Acrylate (ADA)

[0141] 3.04 g of 1-adamantanol and 60 mL of anhydrous dichloromethane were added to the reactor and stirred until fully dissolved, and then 3 g of triethylamine was added. The mixed solution was kept stirring at 0 °C for 40 min. 3.62 g of acryloyl chloride diluted with 25 mL of anhydrous dichloromethane was added dropwise to the above mixed solution at 0 °C through a constant pressure dropping funnel. After the dropwise addition, the temperature was slowly raised to room temperature and the stirring was continued for 18 h. After the end, the insoluble matter was filtered out and the filtrate was collected; the filtrate was washed three times with 0.1 M HCl aqueous solution, 0.5 wt% NaHCO3 solution, and distilled water respectively, and the organic phase was collected and concentrated by low-temperature vacuum rotary evaporation at 4 °C. Purification was performed by column chromatography, in which the eluent was V 乙酸乙酯 :V 正己烷 =1:15, and the product ADA was obtained, which was stored at low temperature for future use.

[0142] 4. Preparation of Thermoelectric Functional Hydrogel (LAMOH-1)

[0143] 0.0144 g LS-CD and 80 μL methanol solution containing ADA (0.01 g / ml) were added to a 1.5 mol / L lithium chloride glycerol / water solution (7 mL), where V 甘油 :V 水 =1:2 and stirred at room temperature for 30 min. Then, 0.02 g of stannous chloride (SnCl2) was added, followed by 0.96 g of acrylamide (AM) and 0.96 g of acrylic acid (AA), and finally 0.024 g of ammonium persulfate (APS) to obtain the thermoelectric functional hydrogel LAMOH-1.

[0144] 5. Preparation of Polyaniline Carbon Fiber Cloth Electrodes

[0145] First, carbon fiber cloth (CWF) was ultrasonically cleaned with ethanol and deionized water for 30 minutes. Then, 0.025 mol of ANI monomer was dissolved in 2.0 mol / L H₂SO₄ solution (25 mL) with magnetic stirring and reacted in an ice-water bath for 1 hour to obtain solution A. Next, 0.025 mol of APS was dissolved in 2.0 mol / L H₂SO₄ solution (25 mL) to prepare solution B. The cleaned CWF served as a support substrate for the direct assembly of polyaniline nanorod arrays via a simple chemical oxidation deposition process. The CWF was vertically immersed in solution A, and solution B was then added to solution A, and the reaction was magnetically stirred in an ice-water bath for 12 hours. The resulting CWF containing polyaniline was rinsed several times with deionized water and annealed in a vacuum oven at 60°C for 2 hours to obtain the product, labeled as PANI@CWF.

[0146] 6. Preparation of Photothermoelectric Conversion Devices

[0147] Take two layers of PANI@CWF electrodes with a size of 1.5 cm×2.5 cm and encapsulate the thermoelectric functional hydrogel in a cylindrical mold made of VHB tape (the size of the VHB tape is 1.5 cm×1.5 cm, and there is a circular cavity with a diameter of 1.2 cm and a height of 1.2 cm inside). In this way, a "sandwich" structure thermoelectric conversion device assembled in the order of electrode-thermoelectric functional hydrogel-electrode is formed. Subsequently, a VHB tape of the same size of 1.5 cm×1.5 cm is glued to the upper electrode, which also has a circular cavity with a diameter of 1.2 cm. AL-NPS@CuS-1 is filled in this cavity to obtain a photothermoelectric conversion device. The structural schematic diagram of the photothermoelectric device is shown in the figure. Figure 1 shown.

[0148] Example 2 Alkali lignin-loaded copper sulfide nanoparticles, thermoelectric functional hydrogel, photothermoelectric device, and preparation method thereof

[0149] The difference from Example 1 is that the glycerol / water solution in step 4 is changed to water.

[0150] The other steps and conditions were the same as those in Example 1, and the alkali lignin-loaded copper sulfide nanoparticles, the thermoelectric functional hydrogel LAMOH-2, and the photothermoelectric device based on LAMOH-2 were obtained in sequence.

[0151] Example 3 Alkali lignin-loaded copper sulfide nanoparticles, thermoelectric functional hydrogel, photothermoelectric device, and preparation method thereof

[0152] The difference from Example 1 is that the lithium chloride of the thermoelectric material in step 4 is replaced by sodium chloride.

[0153] Other steps and conditions are the same as those in Example 1, and alkaline lignin loaded copper sulfide nanoparticles, thermoelectric functional hydrogel LAMOH-3 and photothermal electric devices based on LAMOH-3 are obtained in turn.

[0154] Comparative Example 1: Alkaline lignin loaded copper sulfide nanoparticles and a preparation method thereof

[0155] The difference from Example 1 is that the alkaline lignin nanoparticles in step 1 are first adsorbed with Cu 2+ , and then reacted with S 2- to replace the blending reaction of alkaline lignin nanoparticles with Cu 2+ , S 2- The specific preparation method comprises the following steps:

[0156] At room temperature 25 ℃, 200 mg of alkaline lignin (AL) is added to a γ-valerolactone / water system solution (GVL / H2O) of 20 mL, wherein V GLY :V H2O = 87:13. Then, ultrasonic treatment is performed for 30 min to ensure that the alkaline lignin is completely dissolved. Then, 2000 g centrifugation is performed for 30 min, and the obtained supernatant is a saturated alkaline lignin solution. The solution is quickly injected into water to form a suspension with a total volume of 200 mL. Thereafter, 10000 g centrifugation is performed for 30 min to precipitate the alkaline lignin nanoparticles (AL-NPs). The precipitated AL-NPs are dispersed in 50 mL ultrapure water and mixed with a CuSO4 solution (0.2 M, 10 mL) under stirring at a speed of 600 rpm / min. The mixed solution is heated to 80 ℃, and a Na2S solution (0.2 M, 10 mL) is added dropwise to react for 30 min. The solution after reaction is dialyzed for 48 h, and AL-NPs@CuS-4 is obtained after rotary evaporation concentration and drying at 50 ℃.

[0157] The alkaline lignin nanoparticles in the above Comparative Example 1 are blended with Cu 2+ , S 2-The preparation method of alkali lignin-loaded copper sulfide nanoparticles by a blending reaction is the method disclosed in the prior art (Xie Y, Qian Y, Li Z, et al. Near-infrared-activated efficient bacteria-killing by lignin-based copper sulfidenanocomposites with an enhanced photothermal effect and peroxidase-like activity[J]. ACS Sustainable Chemistry&Engineering, 2021, 9(18): 6479-6488.).

[0158] Comparative Example 2 An alkali lignin-loaded copper sulfide composite material and its preparation method

[0159] The difference from Example 1 is that the alkali lignin in step 1 is not prepared into nanoparticles loaded with copper sulfide in advance, but copper sulfide is directly loaded in the form of alkali lignin. The specific preparation method includes the following steps:

[0160] Alkali lignin (AL) was dispersed in 200 mL of ultrapure water, and 3.9 g of copper sulfate pentahydrate (CuSO4·5H2O) was added. The mixture was stirred at room temperature for 12 h. The mixture was then centrifuged at 8000 rpm for 15 min, the supernatant removed, and the precipitate retained. The resulting precipitate was dispersed in 100 mL of deionized water, 100 mg of sodium sulfide nonahydrate (Na2S·9H2O) was added, and the mixture was stirred in a 60°C water bath for 5 h. The mixture was centrifuged again at 8000 rpm for 15 min, the supernatant removed, and the precipitate retained. Finally, the precipitate was freeze-dried in a vacuum oven for 2 days to yield the alkali lignin-based photothermal conversion material (AL@CuS).

[0161] Experimental examples: Performance characterization of photothermal conversion materials, thermoelectric functional hydrogels, and photothermal electric conversion devices

[0162] 1. Characterization of the structure and morphology of photothermal conversion materials

[0163] In order to characterize the successful preparation of the AL-NPs@CuS-1 composite material prepared in Example 1, infrared spectroscopy was performed. Figure 2 As shown, 1113 cm -1 and 1513 cm -1 The characteristic peak at 617 cm corresponds to the CO and aromatic skeleton vibration of AL. In addition to the characteristic peak of AL, the AL-NPs@CuS-1 composite material -1The peak corresponding to Cu-S stretching is also shown at , which indicates the successful construction of the AL-NPs@CuS-1 composite material. Further, the alkali lignin-supported copper sulfide nanoparticles prepared in Example 1 and Comparative Example 1 were characterized by SEM. Figure 3 As shown in Example 1, the AL-NPs@CuS-1 composite material prepared in Example 1 has a particle size of about 100 nm, and the particles are small and evenly dispersed, which provides a basis for its excellent photothermal performance. 2+ , and then with S 2- In Comparative Example 1, although alkali lignin was also used to prepare nanoparticles, its 2+ and S 2- The blending reaction results in uneven particle size and aggregation of the prepared nanoparticles ( Figure 4 ), which in turn affects the performance of the photothermal conversion material.

[0164] The SEM images of the alkali lignin-supported copper sulfide nanoparticles prepared in Examples 2-3 are similar to the SEM images of the alkali lignin-supported copper sulfide nanoparticles in Example 1, and are not described again here.

[0165] 2. Characterization of photothermal properties of photothermal conversion materials

[0166] Alkali lignin-loaded copper sulfide nanoparticles or alkali lignin-loaded copper sulfide composite material powders were piled into a circle with a diameter of 1 cm and a thickness of 1 mm, and placed under a CEL-HXUV300-T3 xenon lamp for 16 minutes. The powders were photographed every 1 minute using a FLIR T530 thermal imaging camera. By comparing the three methods for preparing photothermal conversion materials in Example 1 and Comparative Examples 1-2, respectively, the method of preparing alkali lignin into nanoparticles and then adsorbing Cu 2+ ... 2+ Then with S 2- Reaction (Example 1), alkali lignin prepared nanoparticles and Cu 2+ 、S 2- Blending reaction (Comparative Example 1), and alkali lignin directly dispersed in water to adsorb Cu 2+ Then with S 2- Reaction (Comparative Example 2), the result is as follows Figure 5As shown, in Comparative Example 1, the alkali lignin-loaded copper sulfide nanoparticles prepared therein had uneven particle size and aggregation, which affected the stability of their photothermal conversion performance. After one week, their stability decreased by about 10%; in Comparative Example 2, the alkali lignin was not prepared into nanoparticles in advance, which limited the loading capacity of copper sulfide, thereby hindering the improvement of its photothermal performance. The photothermal conversion material prepared by the preparation method adopted in Example 1 not only has good photothermal conversion performance, but also has excellent long-term stability. The photothermal conversion performance of the obtained alkali lignin-loaded copper sulfide nanoparticles was measured after being placed for one week, and its photothermal conversion performance was basically the same as that of the freshly prepared material. This is because the stepwise reaction strategy adopted in Example 1 effectively avoids the aggregation of particles, and the obtained AL-NPs@CuS-1 composite material can be evenly dispersed and has a better particle size. This preparation method promotes the photothermal conversion of alkali lignin nanoparticles to Cu 2+ Highly efficient adsorption, ensuring that 2- A uniform copper sulfide structure is formed during the reaction, thereby improving the material's photothermal conversion efficiency and long-term stability.

[0167] Furthermore, the photothermal conversion properties of the photothermal conversion material in Example 1 were characterized by simulating different light power densities under sunlight irradiation. Figure 6 a and 6b, the surface temperature of alkali lignin-loaded copper sulfide nanoparticles increased significantly with the increase of the light power density of simulated sunlight, and the maximum temperature rise (ΔT) was linearly related to the light power density, which proved that the temperature of the composite material can be precisely controlled by the light power density. Figure 6 c investigated the cyclic characteristics of the photothermal conversion effect of alkali lignin-supported copper sulfide nanoparticles. As shown in the figure, the photothermal conversion effect of the alkali lignin-supported copper sulfide nanoparticles remained unchanged over three cycles of simulated solar radiation, demonstrating good photothermal conversion cyclic characteristics. These results demonstrate that the alkali lignin-supported copper sulfide nanoparticles prepared in this application have excellent photothermal performance and can effectively convert light energy into heat energy. The resulting heat energy is further utilized by thermoelectric conversion materials to convert it into electrical energy.

[0168] 3. Characterization of the Antifreeze and Water Retention Properties of Thermoelectric Functional Hydrogels

[0169] The antifreeze and water retention performance of the thermoelectric functional hydrogel of Example 1 was characterized. Figure 7 As shown in Figure a, after storage at 25°C for 7 days, the LAMOH-1 hydrogel can still maintain more than 70% of its initial weight, indicating that the addition of humectant glycerol during the preparation of thermoelectric functional hydrogel can keep the water content of the hydrogel within a higher range, which is beneficial to maintaining the stability of the hydrogel and extending its service life.

[0170] In order to further study the anti-freezing performance of the LAMOH-1 hydrogel, the present application verifies the conductive condition of the hydrogel under low temperature, and the results are as shown in Figure 7 Regardless of room temperature or-20℃, the small light bulb of the hydrogel circuit can still keep on, proving that it can still keep the transmission of electrons under low temperature and has excellent anti-freezing performance.

[0171] 4. Performance test of the photothermal electric device

[0172] The energy density of the photothermal electric device in Example 1 is tested to characterize its photoelectric conversion performance, and the voltage is close to saturation state with a change rate of ≤0.3 mV min -1 . Then the power output level is obtained by externally connecting various resistances, and the energy density in the 1-hour discharging process is calculated by integrating the output power curve, and the average power density under external load is calculated by the equation P=E / Δt, wherein ∆t is the total duration of the discharging stage in one thermal cycle, and the instantaneous output power is obtained by multiplying the voltage and the current.

[0173] The results are shown in Figure 8 Under the light intensity of 100 mW / cm 2 , the open-circuit voltage of the photothermal electric device reaches 0.297 V, and under the light intensity of 200 mW / cm 2 , the open-circuit voltage reaches a maximum of 0.403 V (as shown in Figure 8 a). At the same time, under the light intensity of 200 mW / cm 2 , Figure 8 b shows the power-time curve of the photothermal electric conversion device in Example 1 in series with a 3 kΩ resistance box, and the energy density reaches 628 J•m -2 in 1 hour. Under the light intensity of 100 mW / cm 2 , the open-circuit voltage presents a small fluctuation near the saturated open-circuit voltage and maintains for at least 28 h (as shown in Figure 8 c), indicating that the organic photothermal electric device has long-time output stability. This indicates that the photothermal electric conversion device prepared by the present application has high photothermal electric conversion efficiency and output stability.

[0174] In summary, the present application innovatively first adsorbs Cu 2+ in the copper salt on the alkali lignin nanoparticles and S 2-The reaction prepared alkali lignin-loaded copper sulfide nanoparticles, which were then assembled with a thermoelectric hydrogel to produce a photothermoelectric device. The alkali lignin-loaded copper sulfide nanoparticles, as a photothermal conversion material, exhibited excellent photothermal conversion efficiency and long-term stability, making them the key to improving the performance of photothermoelectric devices. The thermoelectric hydrogel maintained excellent thermoelectric and water-retention properties, enhancing the hydrogel's stability and durability. The photothermoelectric device constructed by assembling the two not only exhibited excellent photothermoelectric performance but also had a long service life, fully demonstrating the enormous potential and application prospects of alkali lignin-loaded copper sulfide nanoparticles in the field of photothermoelectric devices.

[0175] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing alkali lignin-loaded copper sulfide nanoparticles, characterized in that: The following steps are involved: The alkali lignin nanoparticles and copper salt solution were fully mixed and centrifuged, and the precipitate was mixed with the S-containing 2- The ion solution is fully mixed and then centrifuged, and the precipitate is dried to obtain alkali lignin-loaded copper sulfide nanoparticles.

2. The preparation method according to claim 1, characterized in that The preparation method of the alkali lignin nanoparticles comprises the following steps: The alkali lignin is fully dissolved in a solvent and then centrifuged. The supernatant is mixed with water to prepare a suspension, which is then centrifuged. The precipitate is the alkali lignin nanoparticles.

3. The preparation method according to claim 1, characterized in that: The S 2- The ions are selected from one or more of sodium sulfide nonahydrate, hydrogen sulfide, and sodium thiosulfate.

4. Alkali lignin-loaded copper sulfide nanoparticles prepared by the preparation method according to any one of claims 1 to 3.

5. A photothermoelectric device, characterized in that: The photothermal electric device is mainly composed of a photothermal conversion material and a thermoelectric conversion device, wherein the photothermal conversion material and the thermoelectric conversion device are electrically connected through electrodes in the thermoelectric conversion device; the photothermal conversion material is the alkali lignin-loaded copper sulfide nanoparticles according to claim 4.

6. The photothermoelectric device according to claim 5, characterized in that: The thermoelectric conversion device includes a stacked structure arranged in sequence: a first electrode, a thermoelectric conversion material, and a second electrode.

7. The photothermoelectric device according to claim 6, characterized in that: The light-to-heat conversion material is disposed on the surface of the first electrode.

8. The photothermoelectric device according to claim 6, characterized in that: The thermoelectric conversion material is a hydrogel with thermoelectric function.

9. The photothermoelectric device according to claim 8, characterized in that: The method for preparing the hydrogel with thermoelectric function comprises the following steps: Cyclodextrin-modified lignin sulfonate and adamantane acrylate are added to a solvent containing thermoelectric materials and mixed evenly. Unsaturated carboxylic acid monomers, acrylamide monomers, metal ions and initiators are added and fully reacted to prepare a hydrogel with thermoelectric function.

10. Use of the alkali lignin-loaded copper sulfide nanoparticles according to claim 4 or the photothermoelectric device according to any one of claims 5 to 9 in the field of photothermoelectric conversion or wearable devices.

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