A wood-based solar evaporator and its preparation method

Abstract

The present invention discloses a wood-based solar evaporator and a preparation method thereof. The preparation method includes: preparing a balsa wood block template DW after removing lignin; based on the balsa wood block template DW, preparing a rebuilt wood RW with a network structure formed by intertwined micro-nano fibers in the pores; mixing lignin nanoparticles LNPs with a Ti<subgt;2< / subgt;C<subgt;3< / subgt;T<subgt;x< / subgt; suspension to prepare a photothermal material LMX; and coating the photothermal material LMX on the surface of RW to obtain the wood-based solar evaporator. The wood-based solar evaporator of the present invention can enhance the streaming potential while improving the evaporation rate, and can be applied in seawater desalination and / or power generation devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite functional materials, and relates to a wood-based solar evaporator and a preparation method thereof. Background Art

[0002] As the cleanest and most sustainable energy source, solar energy has promoted the development of solar desalination technology in recent years. In particular, solar photothermal interface evaporation technology (SPIE) has attracted much attention due to its low usage of photothermal materials, high photothermal conversion efficiency, and low heat loss. As a natural carbon fixation material, wood can significantly reduce global carbon emissions during the preparation of evaporators compared with petroleum-based compounds. More importantly, the natural porous structure of wood provides capillary effect and water storage capacity of 100-170%, making it an ideal substrate for SPIE.

[0003] However, further improving the evaporation rate of wood-based solar interface evaporator (W-SPIE) remains a major challenge. Summary of the Invention

[0004] The conjugated effect and local surface plasmon resonance of two-dimensional material MXene enhance its photothermal conversion and light absorption capabilities. Ti3C2T x can achieve a photothermal conversion efficiency close to 100% at specific wavelengths. Lignin is the second largest renewable resource on earth, containing a large number of aromatic rings and conjugated structures, endowing it with excellent photothermal conversion performance. However, at some wavelengths (especially in the ultraviolet band), the light absorption ability of Ti3C2T x is lacking, while the light absorption ability of lignin in the visible and near-infrared bands has some defects. Therefore, how to improve the light absorption ability of these two photothermal materials is crucial for promoting their practical applications.

[0005] In the solar interface evaporation technology SPIE, the evaporation process involves the flow of water through the wood channels. Increasing the water flow rate not only improves the evaporation rate but also enhances the streaming potential. It is found that the direct interaction between water and solids generates electric energy through a process called streaming potential. In narrow channels, electrolytes generate voltage under a pressure gradient. This discovery lays the foundation for using nanomaterials for water energy harvesting. Harvesting electric energy during the evaporation process is of great significance for alleviating energy shortage and promoting environmental protection. As the research progresses, the mechanism of this phenomenon is gradually revealed. During the evaporation process, water passes through the porous medium, generating an electric double layer (EDL) at the solid-liquid interface, thus generating streaming voltage and current. In addition, as the evaporation proceeds, the salt concentration inside the evaporator increases compared to the initial solution. The concentration difference between the evaporator and the seawater to be purified synergistically acts with the electric double layer EDL, enhancing the conditions for generating streaming potential. Devices made of metal materials, porous carbon materials, etc. have been developed to harvest this electric energy.

[0006] However, due to the large water flow resistance and the weak interaction between water and materials, the collected electrical energy is often insufficient. Improving this requires improvements in structural design and an increase in water flow rate. Therefore, redesigning the pore structure of wood is of great significance for enhancing the streaming potential and thus promoting the implementation of hydrovoltaic power generation. In addition, this process also meets the goal of increasing the evaporation rate.

[0007] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a wood-based solar evaporator and a preparation method thereof. The prepared wood-based solar evaporator can enhance the streaming potential while increasing the evaporation rate.

[0008] To achieve the above object, the present invention is implemented by the following technical solutions:

[0009] In the first aspect, a preparation method of a wood-based solar evaporator is provided, including the following steps:

[0010] S1, preparing a balsa wood block template DW after removing lignin;

[0011] S2, based on the balsa wood block template DW, preparing a rebuilt wood RW with a network structure formed by intertwined micro-nano fibers in the pores;

[0012] S3, mixing lignin nanoparticles LNPs with Ti2C3T x suspension to prepare a photothermal material LMX;

[0013] S4, coating the photothermal material LMX on the surface of the rebuilt wood RW to obtain a wood-based solar evaporator.

[0014] In some embodiments, in step S1, preparing the balsa wood block template DW after removing lignin includes:

[0015] Placing the balsa wood block in a container, adding an acetate buffer solution and sodium chlorite, and heating and reacting to remove lignin;

[0016] After the reaction is completed, soaking the balsa wood block in water to perform hydrophilic modification on the balsa wood block to obtain a water-containing balsa wood block template DW.

[0017] It should be noted that the mechanism of lignin removal by sodium chlorite is that chlorine dioxide will undergo a single-electron transfer reaction with the phenolic and non-phenolic ends of lignin to form chlorite and non-phenolic radical intermediates. Subsequently, chlorine dioxide will react with radical substances to form hypochlorite esters. The effectiveness of this reaction depends on the pH value of the solution. At high pH, this reaction tends to generate chlorate to inhibit lignin oxidation, while at low pH, the opposite is true. Therefore, a buffer solution is needed to make the pH value of the solution change less, so as to maximize the generation of chlorides and reduce the generation of chlorite and chlorate to efficiently remove lignin.

[0018] In some embodiments, in step S1, at least any one of the following is satisfied:

[0019] The volume size of the basswood block is 2*2*2 cm 3 ;

[0020] The acetate buffer solution is an acetic acid-sodium acetate buffer solution with pH = 4.6;

[0021] The heating reaction includes: after sealing the container, water bath heating is adopted, and the heating temperature is 70~90 °C, preferably 80 °C;

[0022] Soaking the basswood block in water includes: soaking under a pressure of 0.04~0.08 MPa, preferably soaking under a pressure of 0.05~0.06 MPa.

[0023] It should be noted that too high a temperature will cause excessive degradation of hemicellulose other than lignin, resulting in the collapse of the original structure of the wood, which is not conducive to the preparation of the wood-based solar evaporator. Therefore, it is better to control the heating temperature at 70~90 °C.

[0024] In some embodiments, step S2 specifically includes:

[0025] Soak the basswood block template DW in absolute ethanol to remove moisture;

[0026] Soak the basswood block template DW containing ethanol in dimethylacetamide DMAc to remove ethanol;

[0027] React the basswood block template DW containing dimethylacetamide DMAc in a dimethylacetamide solution of LiCl to dissolve the cellulose part of the wood cell wall;

[0028] React the basswood block template DW with the dissolved cellulose in an anti-solvent acetone to in-situ generate a reticulated intertwined structure, and then soak it in deionized water to remove acetone, obtaining the water-containing rebuilt wood RW.

[0029] It should be noted that LiCl will interact with the hydroxyl groups in cellulose to form ion pairs or complexes, and these ion pairs weaken the hydrogen bond interactions inside and between cellulose molecules. In addition, dimethylacetamide DMAc is a highly polar solvent, and when the hydrogen bonds inside and between cellulose molecules are broken, it can be stably dissolved in DMAc.

[0030] In some embodiments, in step S2, at least any one of the following is satisfied:

[0031] The soaking is carried out under a pressure of 0.04 - 0.08 MPa, preferably under a pressure of 0.05 - 0.06 MPa;

[0032] The mass concentration of LiCl in the dimethylacetamide solution of LiCl is 6 - 10 wt%, preferably 8 wt%;

[0033] Reacting the balsa wood block template DW containing dimethylacetamide DMAc in the dimethylacetamide solution of LiCl includes: the reaction temperature is 25 - 40 °C, reacting under a pressure of 0.04 - 0.08 MPa, preferably the reaction temperature is 35 °C, reacting under a pressure of 0.06 MPa;

[0034] Reacting the balsa wood block template DW with partially dissolved cellulose in the antisolvent acetone includes: the reaction temperature is 25 - 40 °C, reacting under a pressure of 0.04 - 0.08 MPa, preferably the reaction temperature is 35 °C, reacting under a pressure of 0.06 MPa;

[0035] After obtaining the water-containing reconstructed wood RW, it further includes freezing the reconstructed wood RW with liquid nitrogen and performing freeze-drying for later use.

[0036] In some embodiments, in step S3, based on the solid mass of lignin nanoparticles LNPs, the addition amount of lignin nanoparticles LNPs is Ti2C3T x in the suspension of Ti2C3T x 5 - 15 wt%.

[0037] It should be noted that too little addition of lignin nanoparticles LNPs in the photothermal material LMX does not maximize the improvement of the light absorption ability of the photothermal material Ti2C3T x while excessive addition will cause too many pores between the sheets of Ti2C3T x to be blocked, thus affecting water evaporation. Through experiments, it is found that controlling the addition amount of lignin nanoparticles LNPs at 5 - 15 wt% has a better effect and can greatly improve the light absorption ability.

[0038] The Ti2C3T x suspension has a concentration of 5 - 15 mg / mL, preferably 10 mg / mL.

[0039] In some embodiments, in step S3, the preparation method of the lignin nanoparticles LNPs includes: dissolving lignin in an acetone solution to obtain a lignin solution; dropping the lignin solution into water under stirring conditions to obtain lignin nanoparticles LNPs.

[0040] Furthermore, in some embodiments, the volume ratio of acetone to water in the acetone solution is 4:1;

[0041] In some embodiments, the concentration of the lignin solution is 100 mg / mL;

[0042] In some embodiments, the lignin solution is dropped into water under stirring conditions, including: the volume ratio of the lignin solution to water is 1:50, and it is dropped at a rate of 0.5 - 2 mL / min (preferably 1 mL / min). During the dropping process, stirring is continuously carried out at a rate of 500 rpm. After the dropping process ends, stirring is continued at a temperature of 25 - 32 °C (preferably 30 °C) for 1 - 8 h.

[0043] In some embodiments, in step S4, the coating amount of the photothermal material LMX on the reconstructed wood RW is 0.1 - 1 mL, preferably 0.6 - 0.7 mL.

[0044] In a second aspect, a wood-based solar evaporator is provided, which is prepared by the above preparation method.

[0045] In a third aspect, the application of the above wood-based solar evaporator in seawater desalination and / or power generation devices is provided

[0046] Compared with the prior art, the beneficial effects achieved by the present invention:

[0047] A wood-based solar evaporator and its preparation method provided by the present invention first perform delignification treatment on balsa wood blocks with an acetic acid / sodium acetate buffer solution with pH = 4.6 and sodium chlorite. Through the oxidation of chlorides, lignin is removed, thereby improving the hydrophilicity of the wood. In addition, the wood cell wall structure becomes relatively loose and the cell wall spacing increases, which is conducive to water transmission. Subsequently, the delignified wood template DW is successively vacuum impregnated in ethanol, N,N-dimethylacetamide (DMAc), and LiCl / DMAc solution through cell wall engineering. The ion pairs formed by LiCl and cellulose hydroxyl groups weaken the hydrogen bond binding between cellulose, so that it is stably dissolved in highly polar DMAc. After the reaction ends, it is placed in the antisolvent acetone to regenerate cellulose in situ inside the wood. The DW becomes a micro-nano structure reconstructed wood (RW) with network-interlaced micro-nano fibers in the internal pores and is reserved after freeze-drying. This step further thins the cell walls of wood cells, broadens the pore structure, and additionally creates some pore structures, greatly improving the specific surface area. At the same time, the pores are filled with cellulose rich in hydroxyl groups to enhance capillary action. In addition, the prepared lignin nanoparticle dispersion is mixed with Ti3C2T xThe dispersion liquid was fully mixed, and after ultrasonic dispersion, it was coated on the surface of RW as a photothermal material (LMX) to prepare a wood-based solar evaporator / generator device (LMX-RW). The newly prepared photothermal material LMX of the present invention has extremely high photothermal conversion efficiency. Even with a very small amount of LMX added, a relatively high temperature can be achieved at the evaporation interface, thus promoting water evaporation. Therefore, LMX-RW has excellent evaporation rate under one sun radiation intensity, and can simultaneously collect purified fresh water resources and electrical energy, and the evaporation rate does not decrease significantly during this process, providing new ideas for solving the problems of scarce fresh water resources and energy shortage and broadening the application direction of wood. Brief Description of the Drawings

[0048] Figure 1 It is a schematic structural diagram of the wood-based solar evaporator in the embodiment of the present invention;

[0049] Figure 2 It is a schematic diagram of the light absorption ability of lignin and Ti2C3T in the embodiment of the present invention x in the present invention;

[0050] Figure 3 It is a schematic diagram of the global average solar light density, and the light absorption abilities of RW and LMX-RW in the embodiment of the present invention;

[0051] Figure 4 It is a schematic diagram of the open circuit voltage of DW, LMX-DW and LMX-RW during the evaporation process in the embodiment of the present invention;

[0052] Figure 5 It is a schematic diagram of the short circuit current of DW, LMX-DW and LMX-RW during the evaporation process in the embodiment of the present invention. Detailed Embodiments

[0053] The present invention will be further described below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0054] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0055] For the purposes of this specification and the appended claims, unless otherwise stated, all numbers expressing quantities, percentages, or proportions, and other numerical values used in this specification and the appended claims are understood to be modified in all instances by the term "about". In addition, all ranges disclosed herein include the endpoints and can be combined independently.

[0056] Example 1: A method for preparing a wood-based solar evaporator, comprising the following steps:

[0057] S1. Prepare the balsa wood template DW after lignin removal;

[0058] Add 40 g of sodium acetate trihydrate and 18.3 mL of acetic acid to 3 L of deionized water, stir well to prepare an acetate buffer solution (acetic acid - sodium acetate buffer solution) with a pH of 4.6;

[0059] Place 8 balsa wood blocks with a volume of 2*2*2 cm 3 in a beaker, add 400 g of the acetate buffer solution and 6 g of sodium chlorite with a purity of 80%, seal it, and heat it in a water bath at 80 °C for 6 h. After the 6-h reaction is completed, replace the acetate buffer solution and sodium chlorite of the same mass, and react for a total of 36 h to remove lignin;

[0060] After the 36-h reaction is completed, place the balsa wood blocks in deionized water, soak them at a pressure of 0.06 MPa for 2 h, and repeat this operation 4 times to remove the residual chemical reagents and obtain the water-containing balsa wood block template DW.

[0061] S2. Based on the balsa wood block template DW, prepare the rebuilt wood RW with a network structure of micro-nano fibers intertwined in the pores;

[0062] Place the water-containing balsa wood block template DW in absolute ethanol, soak it at a pressure of 0.06 MPa for 2 h to remove water, and repeat this operation 4 times;

[0063] Place the ethanol-containing balsa wood block template DW in dimethylacetamide DMAc, soak it at a pressure of 0.06 MPa for 2 h to remove ethanol, and repeat this operation 4 times;

[0064] Place the DMAc-containing balsa wood block template DW in LiCl / DMAc with a LiCl mass fraction of 8 wt%, react at 35 °C under a pressure of 0.06 MPa for 36 h to dissolve the cellulose part of the wood cell wall;

[0065] Place the balsa wood block with the dissolved cellulose part in the anti-solvent acetone, react at 35 °C under a pressure of 0.06 MPa for 6 h to in-situ regenerate the cellulose into a networked intertwined structure to become the rebuilt wood RW;

[0066] Place the rebuilt wood RW containing acetone in deionized water and soak it at a pressure of 0.06 MPa for 2 h to remove acetone. This operation is repeated 4 times;

[0067] Rapidly freeze the water-containing rebuilt wood RW with liquid nitrogen and perform freeze-drying for later use.

[0068] S3, Preparation of the photothermal material LMX;

[0069] Prepare an acetone solution by mixing acetone and water in a volume ratio of 4:1;

[0070] Dissolve lignin in the acetone solution to prepare a lignin solution with a concentration of 100 mg / mL;

[0071] Drop 4 mL of the lignin solution into 200 mL of deionized water at a rate of 1 mL / min. During the dropping process, continuously stir at a rate of 500 rpm. After the dropping process ends, continue to stir at 30 °C for 2 h to prepare lignin nanoparticles (LNPs) and measure the solid content for later use;

[0072] Mix 1 g of Ti3AlC2 powder with 20 mL of hydrochloric acid with a concentration of 36%, then add 16 g of LiF, and react at 42 °C for 36 h. After the reaction ends, centrifuge the mixture at 3000 rpm for 30 min to remove the supernatant;

[0073] Add 200 mL of deionized water to the centrifuged solid and ultrasonically disperse it in an N2 atmosphere for 1 h. Centrifuge the dispersion at 3000 rpm for 10 min, collect the liquid and perform freeze-drying to obtain the Ti2C3T x solid, and prepare the MXene material Ti2C3T x solid into a 10 mg / mL Ti2C3T x suspension;

[0074] Mix the lignin nanoparticles LNPs with an addition amount of 10 wt% (solid mass) and 0.7 mL of Ti2C3T x suspension (containing 7 mg of Ti2C3T x ) and ultrasonically disperse for 5 min to become the photothermal material LMX.

[0075] S4, Coat the photothermal material LMX on the surface of RW to obtain a wood-based solar evaporator;

[0076] Coat 0.2 mL of LMX on the surface of RW. Repeat this operation until all the LMX is used up after there is no obvious liquid on the surface.

[0077] Example 2: A preparation method of a wood-based solar evaporator, comprising the following steps:

[0078] S1. Prepare the balsa wood template DW after removing lignin;

[0079] Add 40 g of sodium acetate trihydrate and 18.3 mL of acetic acid to 3 L of deionized water, stir well to obtain an acetate buffer solution with a pH of 4.6;

[0080] Place 8 balsa wood blocks with a volume of 2*2*2 cm 3 in a beaker, add 400 g of the acetate buffer solution and 6 g of sodium chlorite with a purity of 80%, seal it, and heat it in a water bath at 80 °C for 6 h. After the 6 h reaction is completed, replace the acetate buffer solution and sodium chlorite of the same mass, and react for a total of 36 h to remove lignin;

[0081] After the 36 h reaction, place the balsa wood blocks in deionized water, soak them at a pressure of 0.06 MPa for 2 h, and repeat this operation 4 times to remove the residual chemical reagents and obtain the water-containing balsa wood block template DW.

[0082] S2. Based on the balsa wood block template DW, prepare the rebuilt wood RW with a network structure formed by intertwined micro-nano fibers in the pores;

[0083] Place the water-containing balsa wood block template DW in absolute ethanol, soak it at a pressure of 0.06 MPa for 2 h to remove water, and repeat this operation 4 times;

[0084] Place the ethanol-containing balsa wood block template DW in dimethylacetamide DMAc, soak it at a pressure of 0.06 MPa for 2 h to remove ethanol, and repeat this operation 4 times;

[0085] Place the DMAc-containing balsa wood block template DW in LiCl / DMAc with a LiCl mass fraction of 8 wt%, and react at 35 °C under a pressure of 0.06 MPa for 36 h to dissolve the cellulose part of the wood cell wall;

[0086] Place the balsa wood block with the dissolved cellulose part in the antisolvent acetone, and react at 35 °C under a pressure of 0.06 MPa for 6 h to in-situ regenerate the cellulose into a network-like intertwined structure to become the rebuilt wood RW;

[0087] Place the rebuilt wood RW containing acetone in deionized water, soak it at a pressure of 0.06 MPa for 2 h to remove acetone, and repeat this operation 4 times;

[0088] Rapidly freeze the water-containing rebuilt wood RW with liquid nitrogen and perform freeze-drying for later use.

[0089] S3, Preparation of the photothermal material LMX;

[0090] Prepare an acetone solution by mixing acetone and water at a volume ratio of 4:1;

[0091] Dissolve lignin in the acetone solution to prepare a lignin solution with a concentration of 100 mg / mL;

[0092] Drop 4 mL of the lignin solution into 200 mL of deionized water at a rate of 1 mL / min. During the dropping process, continuously stir at a rate of 500 rpm. After the dropping process is completed, continue to stir at 30 °C for 2 h to prepare lignin nanoparticles (LNPs) and measure the solid content for standby;

[0093] Mix 1 g of Ti3AlC2 powder with 20 mL of hydrochloric acid with a concentration of 36%, then add 16 g of LiF, and react at 42 °C for 36 h. After the reaction is completed, centrifuge the mixture at 3000 rpm for 30 min to remove the supernatant;

[0094] Add 200 mL of deionized water to the centrifuged solid, and ultrasonically disperse it in an N2 atmosphere for 1 h. Centrifuge the dispersion at 3000 rpm for 10 min, collect the liquid and perform freeze-drying to obtain the Ti2C3T x solid, and prepare the Ti2C3T x solid into a 10 mg / mL MXene material Ti2C3T x suspension;

[0095] Mix the lignin nanoparticles LNPs with an addition amount of 5 wt% (solid mass) and 0.7 mL of Ti2C3T x suspension (containing 7 mg of Ti2C3T x ), and ultrasonically disperse for 5 min to form the photothermal material LMX.

[0096] S4, Coat the photothermal material LMX on the surface of RW to obtain a wood-based solar evaporator;

[0097] Coat 0.2 mL of LMX on the surface of RW, and repeat this operation until there is no obvious liquid on the surface until all the LMX is used up.

[0098] Example 3: A preparation method of a wood-based solar evaporator, comprising the following steps:

[0099] S1, Prepare the balsa wood template DW after removing lignin;

[0100] Add 40 g of sodium acetate trihydrate and 18.3 mL of acetic acid to 3 L of deionized water, stir well to prepare an acetate buffer solution with a pH of 4.6;

[0101] Place 8 basswood blocks with a volume of 2*2*2 cm 3 in a beaker, add 400 g of acetate buffer solution and 6 g of sodium chlorite with a purity of 80%, seal it, and heat it in a water bath at 80 °C for 6 h. After the 6 h reaction is completed, replace the acetate buffer solution and sodium chlorite of the same mass, and react for a total of 36 h to remove lignin;

[0102] After the 36 h reaction, place the basswood blocks in deionized water and soak them at a pressure of 0.06 MPa for 2 h. After that, repeat this operation 4 times to remove the residual chemical reagents and obtain a water-containing basswood block template DW.

[0103] S2. Based on the basswood block template DW, prepare a rebuilt wood RW with a network structure formed by the interweaving of micro-nano fibers in the pores;

[0104] Place the water-containing basswood block template DW in absolute ethanol and soak it at a pressure of 0.06 MPa for 2 h to remove water. Repeat this operation 4 times;

[0105] Place the ethanol-containing basswood block template DW in dimethylacetamide DMAc and soak it at a pressure of 0.06 MPa for 2 h to remove ethanol. Repeat this operation 4 times;

[0106] Place the DMAc-containing basswood block template DW in LiCl / DMAc with a LiCl mass fraction of 8 wt% and react at 35 °C under a pressure of 0.06 MPa for 36 h to dissolve part of the cellulose in the wood cell wall;

[0107] Place the basswood block with partially dissolved cellulose in the antisolvent acetone and react at 35 °C under a pressure of 0.06 MPa for 6 h to regenerate the cellulose in situ into a networked intertwined structure to become a rebuilt wood RW;

[0108] Place the rebuilt wood RW containing acetone in deionized water and soak it at a pressure of 0.06 MPa for 2 h to remove acetone. Repeat this operation 4 times;

[0109] Rapidly freeze the water-containing rebuilt wood RW with liquid nitrogen and perform freeze-drying for later use.

[0110] S3. Preparation of the photothermal material LMX;

[0111] Prepare an acetone solution by mixing acetone and water in a volume ratio of 4:1;

[0112] Dissolve lignin in an acetone solution to prepare a lignin solution with a concentration of 100 mg / mL;

[0113] Drop 4 mL of the lignin solution into 200 mL of deionized water at a rate of 1 mL / min. During the dropping process, continuously stir at a rate of 500 rpm. After the dropping process is completed, continue to stir at 30°C for 2 h to prepare lignin nanoparticles (LNPs) and measure the solid content for standby;

[0114] Mix 1 g of Ti3AlC2 powder with 20 mL of hydrochloric acid with a concentration of 36%, then add 16 g of LiF, and react at 42°C for 36 h. After the reaction is completed, centrifuge the mixture at 3000 rpm for 30 min to remove the supernatant;

[0115] Add 200 mL of deionized water to the centrifuged solid, and ultrasonically disperse it in an N2 atmosphere for 1 h. Centrifuge the dispersion at 3000 rpm for 10 min, collect the liquid and perform freeze-drying to obtain Ti2C3T x solid, and prepare the Ti2C3T x solid into a 10mg / mL MXene material Ti2C3T x suspension;

[0116] Mix the lignin nanoparticles LNPs with an addition amount of 15 wt% (solid mass) with 0.7 mL of Ti2C3T x suspension (containing 7 mg of Ti2C3T x ), and ultrasonically disperse for 5 min to become the photothermal material LMX.

[0117] S4. Coat the photothermal material LMX on the RW surface to obtain a wood-based solar evaporator;

[0118] Coat 0.2 mL of LMX on the RW surface. After there is no obvious liquid on the surface, repeat this operation until all the LMX is used up.

[0119] Example 4: The preparation method of a wood-based solar evaporator refers to Example 1, and the only difference is:

[0120] Mix the lignin nanoparticles LNPs with an addition amount of 3 wt% (solid mass) with 0.7 mL of Ti2C3T x suspension (containing 7 mg of Ti2C3T x ), and ultrasonically disperse for 5 min to become the photothermal material LMX.

[0121] Example 5: The preparation method of a wood-based solar evaporator refers to Example 1, and the only difference is:

[0122] The lignin nanoparticles LNPs were mixed with 0.7 mL of Ti2C3T x suspension (containing 7 mg of Ti2C3T x ) at an addition amount of 20 wt% (solid mass), and after ultrasonic dispersion for 5 min, it became the photothermal material LMX.

[0123] Comparative Example 1: A preparation method of a wood-based solar evaporator, comprising the following steps:

[0124] S1. Prepare the balsa wood template DW after removing lignin;

[0125] Add 40 g of sodium acetate trihydrate and 18.3 mL of acetic acid to 3 L of deionized water, stir well to obtain an acetate buffer solution with a pH of 4.6;

[0126] Place 8 balsa wood blocks with a volume of 2*2*2 cm 3 in a beaker, add 400 g of acetate buffer solution and 6 g of sodium chlorite with a purity of 80%, seal it, and heat it in a water bath at 80 °C for 6 h. After the 6 h reaction is completed, replace the acetate buffer solution and sodium chlorite of the same mass, and react for a total of 36 h to remove lignin;

[0127] After the 36 h reaction, place the balsa wood blocks in deionized water, soak them at a pressure of 0.06 MPa for 2 h, and repeat this operation 4 times after completion to remove the residual chemical reagents and obtain the water-containing balsa wood block template DW.

[0128] Freeze-dry the water-containing balsa wood block template DW and directly use it as the wood-based solar evaporator DW.

[0129] Comparative Example 2: A preparation method of a wood-based solar evaporator, comprising the following steps:

[0130] S1. Prepare the balsa wood template DW after removing lignin;

[0131] Add 40 g of sodium acetate trihydrate and 18.3 mL of acetic acid to 3 L of deionized water, stir well to obtain an acetate buffer solution with a pH of 4.6;

[0132] Place 8 balsa wood blocks with a volume of 2*2*2 cm 3 in a beaker, add 400 g of acetate buffer solution and 6 g of sodium chlorite with a purity of 80%, seal it, and heat it in a water bath at 80 °C for 6 h. After the 6 h reaction is completed, replace the acetate buffer solution and sodium chlorite of the same mass, and react for a total of 36 h to remove lignin;

[0133] After the reaction for 36 h, the balsa wood blocks were placed in deionized water and soaked at a pressure of 0.06 MPa for 2 h. After that, this operation was repeated 4 times to remove the residual chemical reagents and obtain the water-containing balsa wood block template DW. After freeze-drying, the available balsa wood block template DW was obtained.

[0134] S2, Preparation of the photothermal material LMX;

[0135] Acetone and water were mixed at a volume ratio of 4:1 to prepare an acetone solution;

[0136] Lignin was dissolved in the acetone solution to prepare a lignin solution with a concentration of 100 mg / mL;

[0137] 4 mL of the lignin solution was added dropwise into 200 mL of deionized water at a rate of 1 mL / min. During the dropping process, continuous stirring was carried out at a rate of 500 rpm. After the dropping process ended, continuous stirring was continued at a temperature of 30 °C for 2 h to prepare lignin nanoparticles (LNPs) and measure the solid content for standby;

[0138] 1 g of Ti3AlC2 powder was mixed with 20 mL of hydrochloric acid with a concentration of 36%, and then 16 g of LiF was added. The reaction was carried out at 42 °C for 36 h. After the reaction ended, the mixture was centrifuged at 3000 rpm for 30 min to remove the supernatant;

[0139] 200 mL of deionized water was added to the centrifuged solid, and ultrasonic dispersion was carried out for 1 h under a nitrogen atmosphere. The dispersion was centrifuged at 3000 rpm for 10 min, and the liquid was collected and freeze-dried to obtain the Ti2C3T x solid. The Ti2C3T x solid was formulated into a 10 mg / mL MXene material Ti2C3T x suspension;

[0140] The lignin nanoparticles LNPs were mixed with 0.7 mL of Ti2C3T x suspension (containing 7 mg of Ti2C3T x ) at an addition amount of 10 wt% (solid mass), and after ultrasonic dispersion for 5 min, it became the photothermal material LMX. S3, Coating the photothermal material LMX on the surface of DW to obtain a wood-based solar evaporator;

[0141] 0.2 mL of LMX was coated on the surface of DW. After there was no obvious liquid on the surface, this operation was repeated until all the LMX was used up to obtain the wood-based solar evaporator LMX-DW.

[0142] As Figure 1As shown, the wood-based solar evaporator prepared in Example 1 has its evaporation surface and bottom surface respectively connected to platinum mesh electrodes to form an electrical device, and electrical signals are collected through an electrochemical workstation.

[0143] The evaporation performance tests and electrical signal collections were carried out on the wood-based solar evaporators LMX-RW prepared in Examples 1-5, the wood-based solar evaporator DW prepared in the comparative example, and LMX-DW.

[0144] Table 1

[0145]

[0146] Table 1 shows the average evaporation rates of Examples 1-5 and Comparative Examples 1-2 after 6 consecutive hours of evaporation at a stable evaporation rate under 1 sun irradiation intensity. The results show that Examples 1-3 all have relatively high evaporation rates, with the highest reaching 2.43 kg m -2 h -1 , while the evaporation rates of Comparative Examples 1-2 are only 0.91 kg m -2 h -1 and 1.85 kg m -2 h -1 respectively. Further comparing Examples 1-3, it is found that the addition of 10 wt% of LNPs results in the maximum evaporation rate.

[0147] Figure 2 The light absorption ability tests of lignin and Ti3C2T x were carried out by an ultraviolet-visible-infrared spectrophotometer. The results show that lignin and Ti3C2T x have complementary light absorption abilities at different wavelengths. The light absorption ability of lignin is stronger than that of Ti3C2T x in the 200-500 nm and 2100-2500 nm wavelength bands, while Ti3C2T x has better light absorption ability in the 500-2100 nm wavelength band.

[0148] Figure 3 The light absorption ability tests of the evaporation surfaces of LMX-RW and RW were carried out by an ultraviolet-visible-infrared spectrophotometer. The results show that after coating the surface of RW with LMX mixed with lignin nanoparticles LNPs and Ti3C2T x , its light absorption ability has been greatly improved compared with the original RW, and the light absorption ability for light with wavelengths between 200-2500 nm basically remains above 90%, which greatly improves the photothermal conversion efficiency.

[0149] Figure 4To test the open-circuit voltage generated during the evaporation process of the wood-based solar evaporator prepared in Example 1 and the wood-based solar evaporators prepared in Comparative Examples 1-2. The open-circuit voltage of LMX-RW is much higher than that generated in Comparative Examples 1-2, about 72 mV. The open-circuit voltages generated by DW and LMX-DW are about 22 mV and 43 mV respectively.

[0150] Figure 5 To test the short-circuit current generated during the evaporation process of the wood-based solar evaporator prepared in Example 1 and the wood-based solar evaporators prepared in Comparative Examples 1-2. The short-circuit current of LMX-RW is much higher than that generated in Comparative Examples 1-2, about 0.3 µA. The short-circuit currents generated by DW and LMX-DW are about 0.2 µA and 0.15 µA respectively.

[0151] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a wood-based solar evaporator, characterized in that, It includes the following steps: S1. Prepare the basswood block template DW after lignin removal; S2. Based on the basswood block template DW, prepare the rebuilt wood RW with a network structure formed by intertwined micro-nano fibers in the pores, specifically including: soaking the basswood block template DW in absolute ethanol to remove moisture; soaking the basswood block template DW containing ethanol in dimethylacetamide to remove ethanol; reacting the basswood block template DW containing dimethylacetamide in a dimethylacetamide solution of LiCl to dissolve part of the cellulose in the wood cell wall; reacting the basswood block template DW with dissolved cellulose in an anti-solvent acetone to in-situ generate a network intertwined structure of the dissolved cellulose, and then soaking it in deionized water to remove acetone to obtain the water-containing rebuilt wood RW; S3. Mix lignin nanoparticles (LNPs) with Ti2C3T x suspension to prepare the photothermal material LMX. Based on the solid mass of the lignin nanoparticles (LNPs), the addition amount of the lignin nanoparticles (LNPs) is 5 - 15 wt% of Ti2C3T x in the Ti2C3T x suspension; S4. Coating the photothermal material LMX on the surface of the rebuilt wood RW to obtain a wood-based solar evaporator.

2. The preparation method of the wood-based solar evaporator according to claim 1, wherein In step S1, preparing the basswood block template DW after lignin removal includes: Placing the basswood block in a container, adding an acetate buffer solution and sodium chlorite, and heating and reacting to remove lignin; After the reaction is completed, soaking the basswood block in water to perform hydrophilic modification on the basswood block to obtain the water-containing basswood block template DW.

3. The preparation method of the wood-based solar evaporator according to claim 2, wherein, In step S1, at least any one of the following is satisfied: The volume dimension of the basswood block is 2*2*2 cm 3 ; The acetate buffer solution is an acetic acid-sodium acetate buffer solution with a pH of 4.6; The heating reaction includes: after sealing the container, using water bath heating, and the heating temperature is 70-90 °C; Soaking the basswood block in water includes: soaking under a pressure of 0.04-0.08 MPa.

4. The preparation method of the wood-based solar evaporator according to claim 1, characterized in that, In step S2, at least any one of the following is satisfied: The soaking is performed under a pressure of 0.04-0.08 MPa; The mass concentration of LiCl in the dimethylacetamide solution of LiCl is 6-10 wt%; Reacting the basswood block template DW containing dimethylacetamide DMAc in a dimethylacetamide solution of LiCl includes: the reaction temperature is 25-40 °C, and the reaction is carried out under a pressure of 0.04-0.08 MPa; Reacting the basswood block template DW with dissolved cellulose in an anti-solvent acetone includes: the reaction temperature is 25-40 °C, and the reaction is carried out under a pressure of 0.04-0.08 MPa.

5. The preparation method of the wood-based solar evaporator according to claim 1, wherein, After obtaining the water-containing rebuilt wood RW, it further includes freezing the rebuilt wood RW with liquid nitrogen and performing freeze-drying for standby.

6. The preparation method of the wood-based solar evaporator according to claim 1, wherein, In step S3, the concentration of the Ti2C3T x suspension is 5 to 15 mg / mL.

7. The preparation method of the wood-based solar evaporator according to claim 1, characterized in that In step S3, the preparation method of the lignin nanoparticles LNPs includes: dissolving lignin in an acetone solution to obtain a lignin solution; dropping the lignin solution into water under stirring conditions to obtain the lignin nanoparticles LNPs.

8. The preparation method of the wood-based solar evaporator according to claim 7, wherein, The volume ratio of acetone to water in the acetone solution is 4:1; And / or, the concentration of the lignin solution is 100 mg / mL; And / or, dropping the lignin solution into water under stirring conditions, including: the volume ratio of the lignin solution to water is 1:50, dropping at a rate of 0.5 - 2 mL / min, continuously stirring at a rate of 500 rpm during the dropping process, and continuing to stir at a temperature of 25 - 32 °C for 1 - 8 h after the dropping process ends.

9. The preparation method of the wood-based solar evaporator according to claim 1, wherein, In step S4, the coating amount of the photothermal material LMX on the rebuilt wood RW is 0.1 - 1 mL.

10. A wood-based solar evaporator, characterized in that, Prepared by the preparation method of the wood-based solar evaporator according to any one of claims 1 to 9.

11. Application of the wood-based solar evaporator according to claim 10 in seawater desalination and / or power generation devices.

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