Biomass-based pn-type dual-drive evaporation power generation device and its preparation method

Abstract

This invention discloses a biomass-based p-n type dual-drive evaporative power generation device, comprising a water tank, an n-type device body, and a p-type device body. The n-type and p-type device bodies are disposed in the water tank. An n-type upper electrode and a p-type upper electrode are respectively disposed at the upper ends of the n-type and p-type device bodies. The p-type device body is composed of ammonium-modified lignin-free balsa wood, and the n-type device body is composed of leather tanned with vegetable tanning agents and retanned with AMPS. This invention also discloses a method for preparing the biomass-based p-n type dual-drive evaporative power generation device. By connecting the bottom with an aqueous solution, positively charged ammonium-modified balsa wood and negatively charged modified leather are integrated to construct a dual-drive water evaporative power generation structure. Under the synergistic enhancement effect of the dual drives, the reverse potential difference generated at the top is significantly increased, making the actual output voltage greater than the sum of the absolute values ​​of the voltages of the p-type and n-type devices operating individually.

Description

Technical Field

[0001] This invention belongs to the field of new energy power generation equipment technology, specifically relating to a biomass-based pn-type dual-drive evaporation power generation device, and also to a method for preparing the biomass-based pn-type dual-drive evaporation power generation device. Background Technology

[0002] Water evaporation power generation technology, as an emerging energy conversion method, demonstrates unique research value and application potential. This technology relies on the evaporation behavior of material surfaces and internal capillary transport mechanisms to continuously convert liquid water into gaseous water, thereby achieving continuous electricity output. Its core advantages are reflected in three aspects: First, water resources are widely distributed on Earth, containing a total energy amount far exceeding humanity's annual energy needs; second, the process has low requirements for the operating environment and can operate stably in various scenarios where liquid water exists; finally, the entire energy conversion process is driven by natural evaporation, requiring no external energy input, which aligns with the green and low-carbon development concept.

[0003] In recent years, researchers have successfully constructed water evaporation power generation devices using functional materials such as carbon black / PVA and polyacrylic acid, preliminarily verifying the feasibility of this technological approach. Currently, research on water evaporation power generation largely focuses on single-polarity materials (n-type or p-type), and still suffers from the following drawbacks: At the material level, existing power generation materials are mostly aerogel or polymer-based systems with weak mechanical properties, prone to creep or cracking during long-term operation; simultaneously, moisture loss in open environments leads to material shrinkage and interruption of ion transport pathways. At the device performance level, existing devices generally have low output voltages (approximately 90~580mV), and the power density is insufficient to meet practical requirements; furthermore, the structure is prone to degradation and ion loss under long-term wet-dry cycling, resulting in insufficient durability. These problems severely restrict the large-scale application of this technology in complex environments. Summary of the Invention

[0004] The purpose of this invention is to provide a biomass-based pn-type dual-drive evaporation power generation device, which solves the problem of low output voltage in existing power generation devices.

[0005] Another objective of this invention is to provide a method for preparing a biomass-based pn-type dual-drive evaporation power generation device.

[0006] The technical solution adopted in this invention is a biomass-based pn-type dual-drive evaporation power generation device, including a water tank containing pure water, an n-type device body, and a p-type device body. The n-type device body and the p-type device body are arranged in the water tank. An n-type device upper electrode is arranged at the upper end of the n-type device body, and a p-type device upper electrode is arranged at the upper end of the p-type device body. The p-type device body is made of ammonium-modified lignin-free balsa wood, and the n-type device body is made of leather tanned with vegetable tanning agents and retanned with AMPS.

[0007] Another technical solution adopted in this invention is a method for preparing a biomass-based pn-type dual-drive evaporation power generation device, specifically as follows: Step S1: The pickled raw hide is tanned with vegetable tanning agents and retanned with AMPS to obtain a leather substrate with a negative charge; Step S2: Cut the leather substrate to form the n-type device body; Step S3: The wood is subjected to lignin removal and ammonium modification treatment to obtain a positively charged wood substrate; Step S4: Cut the wood substrate to form the p-type device body; Step S5: Connect the p-type device body and the n-type device body through the aqueous solution in the water tank, and attach the upper electrode of the n-type device and the upper electrode of the p-type device to the upper ends of the n-type device body and the p-type device body respectively to form a pn-type dual-drive evaporation power generation device.

[0008] The invention is further characterized in that, In step S1, specifically: Step S1.1: Place the pickled raw hides into salt and water and rotate them. Add acid to adjust the pH of the solution to form the first mixed system. Step S1.2: Add vegetable tannin to the rotating first mixing system in three portions to form a second mixing system. Continue rotating at 20-25°C for 2-3 hours. Add alkali to the second mixing system to adjust the pH value to 3.8-4.2 again. Then raise the temperature to 40-45°C and continue rotating for 0.5-2 hours. Let it stand for 8-12 hours. Step S1.3: Add AMPS to the solution in step 1.2 to form a third mixing system, then heat to 38-45°C and continue to rotate for 1-2 hours. Add APS and continue to rotate for 0.5-1 hour. Remove the leather and air dry to obtain tanned leather.

[0009] In step S1.1, the pH value of the first mixing system is 4.2 to 4.8; the salt is sodium chloride, ammonium chloride or magnesium sulfate; the acid is formic acid, lactic acid or oxalic acid; the raw hide is sheepskin, cowhide or pigskin; the system temperature is 20 to 25°C during rotation; and the rotation time is 0.5 to 1 hour.

[0010] In step S1.2, the vegetable tanning agent is tannin of mandarin orange or tannin of bayberry; the added alkali is Na2CO3 or NaHCO3.

[0011] In step S3, specifically: Step S3.1: Mix the wood with alkaline solution and stir magnetically for 4-8 hours. Then adjust the pH of the solution to 12 and perform lignin removal treatment. After washing several times with distilled water, pre-freeze for more than 12 hours and freeze-dry to obtain lignin-removed wood. Step S3.2: Mix the lignin-free wood with CHPTAC and perform ammonium modification for 4-8 hours. Then wash it several times with distilled water, pre-freeze it for more than 12 hours, and freeze-dry it to obtain a positively charged wood substrate.

[0012] In step S3.1, the freeze-drying temperature is -50 to -60℃ and the freeze-drying time is 24 to 48 hours. The alkaline solution is a mixture of NaOH, Na2SO3 and water, and the mass ratio of NaOH, Na2SO3 and water is 100 to 200: 50 to 100: 850 to 1700.

[0013] In step S3.2, the wood is balsa wood or balsa wood.

[0014] The beneficial effects of this invention are: This invention relates to a biomass-based pn-type dual-drive evaporation power generation device. The device integrates ammonium-modified balsa wood (p-type) with a permanently positively charged surface and modified leather (n-type) with a permanently negatively charged surface via an aqueous solution connection at the bottom, constructing a dual-drive water evaporation power generation structure. When the bottom of the device contacts a water source, water is continuously transported upwards along the multi-level pores inside the material under capillary action. According to the electric double-layer theory, the positive charge on the surface of the p-type material induces anions (OH-) in the water. - The ions migrate towards the top and accumulate, while the negative charge on the surface of the n-type material induces cations (H+) to migrate and accumulate. + The ions migrate and accumulate at the top. Because the bottoms of the two devices form a shared ion loop through the aqueous solution, the reverse potential difference generated at the top increases significantly under the synergistic enhancement effect of the dual-drive system, making the actual output voltage greater than the sum of the absolute voltages of the p-type and n-type devices operating individually. This design effectively overcomes the inherent bottleneck of excessively low output voltage in a single water-voltaic device. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the biomass-based pn-type dual-drive evaporation power generation device of the present invention; Figure 2 This is a schematic diagram of the structure of the pn-type dual-drive evaporation power generation device based on biomass according to the present invention; Figure 3 This is a flowchart illustrating the preparation method of the biomass-based pn-type dual-drive evaporation power generation device of the present invention. Figure 4 This is a flowchart of the tanning process of raw hides in the preparation method of the present invention; Figure 5This is a stress-strain curve of the leather in Embodiment 1 of the present invention; Figure 6 This is a voltage-time curve of the power generation device according to Embodiment 1 of the present invention; Figure 7 This is a stress-strain curve of the leather in Embodiment 2 of the present invention; Figure 8 This is a stress-strain curve of the leather in Embodiment 3 of the present invention.

[0016] Among them, 1. water tank, 2. upper electrode of n-type device, 3. body of n-type device, 4. upper electrode of p-type device, and 5. body of p-type device. Detailed Implementation

[0017] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0018] This invention relates to a biomass-based pn-type dual-drive evaporative power generation device, such as... Figure 1 and Figure 2 As shown, the device includes a water tank 1 filled with pure water, an n-type device body 3, and a p-type device body 5. The n-type device body 3 and the p-type device body 5 are disposed in the water tank 1. An n-type device upper electrode 2 is disposed at the upper end of the n-type device body 3, and a p-type device upper electrode 4 is disposed at the upper end of the p-type device body 5. The p-type device body 5 is made of lignin-free balsa wood that has been ammonium-modified, and the n-type device body 3 is made of leather that has been tanned with vegetable tanning agents and retanned with AMPS (2-acrylamido-2-methylpropanesulfonic acid). The leather and balsa wood have a rich multi-level porous structure, which provides natural directional channels for the migration of hydrated ions. Both the n-type device body 3 and the p-type device body 5 are planar or cylindrical structures; the dimensions of the p-type device body 5 and the n-type device body 3 are 1cm × 5cm.

[0019] The materials of the upper electrode 2 of the n-type device and the upper electrode 4 of the p-type device are any one of iron, copper, aluminum, gold, silver, titanium, platinum, and carbon fiber cloth; the material of the water tank 1 is any one of glass, polymethyl methacrylate, polyethylene, and polypropylene. See Figure 1The principle of the aforementioned biomass-based pn-type dual-drive evaporation power generation device is as follows: When one end of the device body comes into contact with liquid water, liquid water molecules continuously enter the device under the impetus of capillary action and evaporation. Upon contact with water molecules, the hydrophilic functional groups in the device body ionize, and the resulting free charged particles flow with the liquid water and water vapor along the pore channels inside the device body, creating a relative displacement and thus generating a potential difference between the upper and lower ends of the device. Since the charged particles flowing inside the p-type device and the n-type device flow in opposite directions, a potential difference is formed at the upper ends of the upper electrode 2 of the n-type device and the upper electrode 4 of the p-type device. At this time, connecting the positive and negative electrodes, i.e., the upper electrode 2 of the n-type device and the upper electrode 4 of the p-type device, can form a closed-loop circuit to output electrical energy.

[0020] It should be noted that the actual output voltage is greater than the sum of the absolute voltages of the p-type and n-type devices operating individually. The underlying mechanism stems from the synergistic enhancement effect under dual-drive: on the one hand, the transverse electric field formed between the p-type and n-type terminals inhibits the diffusion of oppositely charged ions within each terminal, resulting in a higher net ion migration flux than when operating individually; on the other hand, the microdroplets with opposite charges evaporating from the two terminals attract each other, accelerating the local evaporation rate. These effects cause the actual voltage of each device to be higher when operating in combination than when operating individually, thus achieving more efficient energy harvesting than simple superposition.

[0021] The present invention relates to a method for preparing a biomass-based pn-type dual-drive evaporation power generation device, such as... Figure 3 As shown, please follow these steps: Step S1: The pickled raw hides are then tanned with vegetable tanning agents and retanned with AMPS. See [link to relevant documentation]. Figure 4 This yields a negatively charged leather substrate; specifically: Step S1.1: Place the pickled raw hides into salt and water and rotate them. Add acid to adjust the pH of the solution to form the first mixed system. The pH of the first mixture is 4.2–4.8; the salt is sodium chloride, ammonium chloride, or magnesium sulfate; the acid is formic acid, lactic acid, or oxalic acid; and the raw hide is sheepskin, cowhide, or pigskin. During rotation, the system temperature is 20–25℃; the rotation time is 0.5–1 hour. S1.2: Add vegetable tanning agent to the rotating first mixing system in three portions to form the second mixing system. Continue rotating at 20-25℃ for 2-3 hours until the raw hide is thoroughly tanned. Add alkali to the second mixing system to adjust the pH value to 3.8-4.2 again. Then raise the temperature to 40-45℃ and continue rotating for 0.5-2 hours. Let it stand for 8-12 hours. The vegetable tannin is either tannin from mandarin orange or tannin from bayberry; the added alkali is either Na2CO3 or NaHCO3; Step S1.3: Add 2-acrylamido-2-methylpropanesulfonic acid (AMPS) to the solution in step 1.2 to form a third mixed system. Then heat to 38-45°C and continue to rotate for 1-2 hours. Add ammonium persulfate (APS) as an initiator to promote the grafting reaction of AMPS. Continue to rotate for 0.5-1 hour, remove the leather and air dry to obtain tanned leather.

[0022] The ratio of raw hide, water, salt, acid, alkali, AMPS, and APS by mass parts is 100-200:100-200:8-16:1-2:2-4:1-2:0.003-0.006. Step S2: Cut the tanned leather substrate to make the n-shaped body 3; Preferably, the tanned leather is cut into rectangles with a length of 50 mm and a width of 10 mm to obtain a planar n-type device body 3, and the thickness of the planar n-type device body 3 is 2.3 mm to 2.8 mm. Preferably, the tanned leather is cut into rectangles with a length of 40 mm and a width of 10 mm, and then rolled into a cylindrical structure with the wide side as the axis to form a three-dimensional n-type device body 3. Step S3: The wood is subjected to lignin removal and ammonium modification treatment to obtain a positively charged wood substrate; specifically: Step S3.1: Mix the wood with alkaline solution and stir magnetically for 4-8 hours. Then adjust the pH of the solution to 12 and perform lignin removal treatment. After washing several times with distilled water, pre-freeze for more than 12 hours, and then freeze-dry using a freeze dryer at a temperature of -50 to -60°C for 24-48 hours to obtain lignin-removed wood. The alkaline solution is a mixture of NaOH, Na2SO3 and water, with a mass ratio of NaOH, Na2SO3 and water of 100-200:50-100:850-1700. Step S3.2: The lignin-free wood is mixed with CHPTAC (3-chloro-2-hydroxypropyltrimethylammonium chloride) for ammoniation modification. The modification time is 4-8 hours. After that, it is washed several times with distilled water and pre-frozen for more than 12 hours. Then, it is freeze-dried in a freeze dryer at a temperature of -50 to -60°C for 24-48 hours to obtain a positively charged wood substrate. The ratio of wood, water, alkali, and CHPTAC by weight is 0.5–2:100–200:8–16:6–15. The wood is balsa wood or balsa wood. Step S4: Cut the positively charged wood substrate to form the p-type device body 5; Step S5: Connect the p-type device body 5 and the n-type device body 3 through the aqueous solution in the water tank 1. The upper electrode 2 of the n-type device is the positive electrode of the device, and the upper electrode 4 of the p-type device is the negative electrode of the device. For a planar n-type device body 3, the n-type device upper electrode 2 and the p-type device upper electrode 4 are respectively attached to the upper ends of the n-type device body 3 and the p-type device body 5 to form a planar evaporation power generation device; for a three-dimensional device body, the n-type device upper electrode 2 and the p-type device upper electrode 4 are respectively attached to the upper ends of the n-type device body 3 and the p-type device body 5 to form a three-dimensional evaporation power generation device.

[0023] The leather and wood used in this invention are both natural biomass materials, widely available, renewable, inexpensive, and environmentally friendly. The leather undergoes tanning with vegetable tanning agents and retanning with AMPS, which not only introduces strongly negatively charged sulfonic acid groups but also significantly improves its mechanical strength and resistance to damp heat. The wood undergoes alkali treatment to remove lignin and is modified with CHPTAC through ammonium hydration, which imparts stable positive charge while optimizing its porous structure and hydrophilicity. Thanks to their natural hierarchical porous structure and stable chemical modification, these two materials fundamentally overcome the application bottlenecks of traditional power generation materials, such as poor mechanical properties, easy water loss and shrinkage, and insufficient durability.

[0024] This invention relates to a biomass-based pn-type dual-drive evaporation power generation device. It employs an integrated and compact structure, with pn devices directly connected via wires and a water source, eliminating the need for complex external circuitry and ensuring reliable operation. The synergistic working mode, based on the same water evaporation-driven ion migration mechanism, significantly improves energy harvesting efficiency. The device combines advantages such as high voltage output, excellent mechanical properties, strong environmental adaptability, and green and economical raw materials, providing an ideal solution for sustainable energy harvesting in complex environments.

[0025] Example 1 The present invention relates to a method for preparing a pn-type dual-drive evaporative power generation device based on sheepskin, specifically as follows: Fabrication of n-type devices: By weight, 100 parts of acid-soaked sheepskin were placed in a rotary drum, and 200 parts of water and 7 parts of salt (NaCl) were added. The drum was rotated at 25°C for 1 hour for neutralization pretreatment. The pH of the hide was checked and found to be 4.2–4.8. Then, tannin tanning was performed: 200 parts of water and 10 parts of tannin were added to the drum, and the drum was rotated at 25°C for 1 hour. Subsequently, 10 parts of tannin were added in two separate additions, each time rotating for 1 hour. Then, 4 parts of alkali were added in 8 separate additions, and the pH of the tanning liquor used to soak the raw hide was tested to be 4.0. Finally, the liquor ratio was increased to 2, the temperature was raised to 40°C, and the drum was rotated for 0.5 hours. After standing overnight, the drum was rotated again for 0.5 hours. AMPS retanning and filling: The solution was changed, and 100 parts water and 1 part AMPS (2-acrylamido-2-methylpropanesulfonic acid) were added to the drum, and the mixture was rotated for 1 hour. Then, 0.003 parts APS (ammonium persulfate) were added, and the mixture was rotated at 45 °C for 0.5 hours. This grafting reaction introduces sulfonic acid groups into the leather fibers to enhance their electronegativity. The treated leather was then removed, thoroughly washed, stretched, and dried to obtain tanned leather.

[0026] The shrinkage temperature of tanned leather is 84.9℃, and the stress-strain curve of the leather is as follows: Figure 5 As shown, the tensile strength is 20.3 MPa, and the elongation at break is 76.0%. The leather is cut into rectangular strips 5cm long and 1cm wide. The upper electrode 2 of the n-type device is then attached to the leather, i.e., the n-type device body 3, to obtain the n-type power generation device. Fabrication of p-type devices: Balsa wood was cut into strips 5 cm long, 1 cm wide, and 0.1 cm thick. These strips were immersed in a mixed solution of 10% sodium hydroxide (NaOH) and 5% sodium carbonate (Na₂CO₃) and treated at 80°C for 4 hours. After removal, the strips were thoroughly rinsed with deionized water and freeze-dried to obtain lignin-free balsa wood. 2 g of the lignin-free balsa wood strips were weighed and placed in a reaction system with 15 g of CHPTAC (3-chloro-2-hydroxypropyltrimethylammonium chloride). The pH was adjusted to 12 with sodium hydroxide, and the reaction was carried out at 60°C for 4 hours to complete the ammonylation modification and impart positive charge to the wood. The modified wood strips were removed, washed with deionized water, and dried. Copper foil was tightly attached to the upper surface as the top electrode to fabricate a p-type power generation device.

[0027] An n-type device body 3 and a p-type device body 5, prepared above, are connected via an aqueous solution. After connection, electrode 2 on the n-type device becomes the positive output terminal of the entire pn-type dual-drive evaporation power generation device, and electrode 4 on the p-type device becomes the negative output terminal of the device. The voltage-time curve is shown below. Figure 6 As shown, the measured output voltage is 800mV.

[0028] Example 2 The present invention relates to a method for preparing a pn-type dual-drive evaporation power generation device based on cowhide, specifically as follows: Fabrication of n-type devices: By weight, 100 parts of acid-soaked cowhide were placed in a rotating drum, and 200 parts of water and 7 parts of salt (NaCl) were added. The drum was rotated at 25°C for 1 hour for neutralization pretreatment. The pH of the hide was checked and found to be 4.2–4.8. Then, tannin tanning was performed: 200 parts of water and 10 parts of tannin were added to the drum, and the drum was rotated at 25°C for 1 hour. Subsequently, 10 parts of tannin were added in two separate additions, each time rotating for 1 hour. Then, 4 parts of alkali were added in 8 separate additions, and the pH of the tanning liquor used to soak the raw hide was tested to be 4.0. Finally, the liquor ratio was increased to 2, the temperature was raised to 40°C, and the drum was rotated for 0.5 hours. After standing overnight, the drum was rotated again for 0.5 hours. AMPS retanning and filling: The solution was changed, and 100 parts water and 1 part AMPS (2-acrylamido-2-methylpropanesulfonic acid) were added to the drum, and the mixture was rotated for 1 hour. Then, 0.003 parts APS (ammonium persulfate) were added, and the mixture was rotated at 45 °C for 0.5 hours. This grafting reaction introduces sulfonic acid groups into the leather fibers to enhance their electronegativity. The treated leather was then removed, thoroughly washed, stretched, and dried to obtain tanned leather.

[0029] The shrinkage temperature of tanned leather is 83.4℃, and the stress-strain curve of the leather is as follows: Figure 7 As shown, the tensile strength is 22.7 MPa, and the elongation at break is 67.3%. The leather is cut into rectangular strips 5cm long and 1cm wide. The upper electrode 2 of the n-type device is attached to the leather, i.e., the n-type device body 3, to obtain the n-type power generation device.

[0030] Fabrication of p-type devices: Balsa wood was cut into strips 5 cm long, 1 cm wide, and 0.1 cm thick. These strips were immersed in a mixed solution of 10% sodium hydroxide (NaOH) and 5% sodium carbonate (Na₂CO₃) and treated at 80°C for 4 hours. After removal, the strips were thoroughly rinsed with deionized water and freeze-dried to obtain lignin-free balsa wood. 2 g of the lignin-free balsa wood strips were weighed and placed in a reaction system with 15 g of CHPTAC (3-chloro-2-hydroxypropyltrimethylammonium chloride). The pH was adjusted to 12 with sodium hydroxide, and the reaction was carried out at 60°C for 4 hours to complete the ammonylation modification and impart positive charge to the wood. The modified wood strips were removed, washed with deionized water, and dried. Copper foil was tightly attached to the upper surface as the top electrode to fabricate a p-type power generation device.

[0031] An n-type device body 3 and a p-type device body 5, prepared above, are connected via an aqueous solution. After connection, electrode 2 on the n-type device becomes the positive output terminal of the entire pn-type dual-drive evaporation power generation device, and electrode 4 on the p-type device becomes the negative output terminal of the device. The measured output voltage is 650 mV.

[0032] Example 3 The present invention relates to a method for preparing a pn-type dual-drive evaporative power generation device based on pigskin, specifically as follows: Fabrication of n-type devices: By weight, 100 parts of the pickled pigskin were placed in a rotating drum, and 200 parts of water and 7 parts of salt (NaCl) were added. The drum was rotated at 25°C for 1 hour for neutralization pretreatment. The pH of the skin was checked and found to be 4.2–4.8. Then, tannin tanning was performed: 200 parts of water and 10 parts of tannin were added to the drum, and the drum was rotated at 25°C for 1 hour. Subsequently, 10 parts of tannin were added in two separate additions, each time rotating for 1 hour. Then, 4 parts of alkali were added in 8 separate additions, and the pH of the tanning liquor used to soak the raw hide was tested to be 4.0. Finally, the liquor ratio was increased to 2, the temperature was raised to 40°C, and the drum was rotated for 0.5 hours. After standing overnight, the drum was rotated again for 0.5 hours. AMPS retanning and filling: The solution was changed, and 100 parts water and 1 part AMPS (2-acrylamido-2-methylpropanesulfonic acid) were added to the drum, and the mixture was rotated for 1 hour. Then, 0.003 parts APS (ammonium persulfate) were added, and the mixture was rotated at 45 °C for 0.5 hours. This grafting reaction introduces sulfonic acid groups into the leather fibers to enhance their electronegativity. The treated leather was then removed, thoroughly washed, stretched, and dried to obtain tanned leather.

[0033] The shrinkage temperature of the obtained tanned leather was 79.8℃, and the stress-strain curve of the leather was as follows: Figure 8 As shown, the tensile strength is 18.0 MPa, and the elongation at break is 65.7%. The leather is cut into rectangular strips 5cm long and 1cm wide. The upper electrode 2 of the n-type device is attached to the leather, i.e., the n-type device body 3, to obtain the n-type power generation device.

[0034] Fabrication of p-type devices: Balsa wood was cut into strips 5 cm long, 1 cm wide, and 0.1 cm thick. These strips were immersed in a mixed solution of 10% sodium hydroxide (NaOH) and 5% sodium carbonate (Na₂CO₃) and treated at 80°C for 4 hours. After removal, the strips were thoroughly rinsed with deionized water and freeze-dried to obtain lignin-free balsa wood. 2 g of the lignin-free balsa wood strips were weighed and placed in a reaction system with 15 g of CHPTAC (3-chloro-2-hydroxypropyltrimethylammonium chloride). The pH was adjusted to 12 with sodium hydroxide, and the reaction was carried out at 60°C for 4 hours to complete the ammonylation modification and impart positive charge to the wood. The modified wood strips were removed, washed with deionized water, and dried. Copper foil was tightly attached to the upper surface as the top electrode to fabricate a p-type power generation device.

[0035] An n-type device body 3 and a p-type device body 5, prepared above, are connected via an aqueous solution. After connection, electrode 2 on the n-type device becomes the positive output terminal of the entire pn-type dual-drive evaporation power generation device, and electrode 4 on the p-type device becomes the negative output terminal of the device. The measured output voltage is 500 mV.

[0036] Example 4 The performance of the pn-type dual-drive evaporation power generation device prepared by the method of this invention was compared with that of an evaporation power generation-seawater desalination device (application number: 202211468668X, publication number: CN 115800812 A). The results are as follows: At the principle level, the device of this invention is a dual-drive synergistic enhancement, with a p-type device driving anions (OH-). - Ascending, n-type devices drive cations (H) + The upward movement of the two devices creates a superposition of reverse potential differences. Simultaneously, the transverse electric field formed at the dry ends of both devices suppresses reverse ion diffusion within their respective systems, increasing the net migration flux. The shared bottom circuit allows cations and anions to migrate directionally and be replenished, forming a highly efficient cycle. The evaporation power generation-seawater desalination device is unipolar driven, relying solely on the negative charge of the leather to drive the cations (H+). + Na + (etc.) As the ions move upward, a potential difference is generated at the top and bottom of the device. Ions migrate in one direction and there is no coupling effect. The potential difference depends entirely on the ion selectivity of a single material.

[0037] In terms of mechanical properties, the tensile strength of the leather in the n-type device of this invention can reach 20.3 MPa, which is 2.78 times that of the evaporation power generation-seawater desalination device (tensile strength 7.3 MPa). This shows that the leather rigidity of this invention is enhanced and the resistance to deformation is greatly improved, which is crucial for maintaining the structural integrity and ion channel stability of the device during long-term operation.

[0038] Regarding the output voltage, the device of this invention is based on the pn dual-drive synergistic enhancement effect. Under the same test conditions, when the sum of the independent voltages of a single device is 580 mV, the actual combined output voltage can reach 800 mV, exceeding the theoretical superposition value by about 37.9%. In contrast, the average output voltage measured by the evaporation power generation-seawater desalination device can reach 1200 mV, but it only relies on the electronegativity of a single device and the spruce biomimetic structure to establish a potential difference, lacking a bipolar coupling mechanism. The potential for increasing the output voltage is limited by the intrinsic ion selectivity and evaporation driving efficiency of the material.

[0039] Example 5 The biomass-based pn-type dual-drive evaporation power generation device of the present invention can generate electricity at different ambient temperatures, such as 10°C, 50°C, and 70°C, and the power generation efficiency is proportional to the ambient temperature.

[0040] Example 6 The biomass-based pn-type dual-drive evaporation power generation device of the present invention can generate electricity under different solar illumination conditions, such as 0.5 sun, 0.75 sun, 1 sun and 2 sun, etc., and the power generation efficiency is proportional to the solar illumination conditions.

[0041] Example 7 The biomass-based pn-type dual-drive evaporation power generation device of the present invention can generate electricity under different relative humidity conditions, such as relative humidity of 20%, 40%, 70%, etc., and the power generation efficiency is inversely proportional to the relative humidity of the environment.

Claims

1. A biomass-based pn-type dual-drive evaporation power generation device, characterized in that, The device includes a water tank (1) containing pure water, an n-type device body (3), and a p-type device body (5). The n-type device body (3) and the p-type device body (5) are disposed in the water tank (1). The upper end of the n-type device body (3) is provided with an n-type device upper electrode (2), and the upper end of the p-type device body (5) is provided with a p-type device upper electrode (4). The p-type device body (5) is made of lignin-free balsa wood that has been modified by ammonium tanning, and the n-type device body (3) is made of leather that has been tanned with vegetable tanning agents and retanned with AMPS.

2. The biomass-based pn-type dual-drive evaporation power generation device as described in claim 1, characterized in that, The n-type device body (3) and the p-type device body (5) are both planar or cylindrical structures; the upper electrode (2) of the n-type device and the upper electrode (4) of the p-type device are made of any one of iron, copper, aluminum, gold, silver, titanium, platinum, or carbon fiber cloth; the water tank (1) is made of any one of glass, polymethyl methacrylate, polyethylene, or polypropylene.

3. The preparation method of the biomass-based pn-type dual-drive evaporation power generation device as described in claim 1, characterized in that, Specifically: Step S1: The pickled raw hide is tanned with vegetable tanning agents and retanned with AMPS to obtain a leather substrate with a negative charge; Step S2: Cut the leather substrate to form the n-type device body; Step S3: The wood is subjected to lignin removal and ammonium modification treatment to obtain a positively charged wood substrate; Step S4: Cut the wood substrate to form the p-type device body; Step S5: Connect the p-type device body and the n-type device body through the aqueous solution in the water tank, and attach the upper electrode of the n-type device and the upper electrode of the p-type device to the upper ends of the n-type device body and the p-type device body respectively to form a pn-type dual-drive evaporation power generation device.

4. The preparation method of the biomass-based pn-type dual-drive evaporation power generation device as described in claim 3, characterized in that, In step S1, specifically: Step S1.1: Place the pickled raw hides into salt and water and rotate them. Add acid to adjust the pH of the solution to form the first mixed system. Step S1.2: Add vegetable tannin to the rotating first mixing system in three portions to form a second mixing system. Continue rotating at 20-25°C for 2-3 hours. Add alkali to the second mixing system to adjust the pH value to 3.8-4.2 again. Then raise the temperature to 40-45°C and continue rotating for 0.5-2 hours. Let it stand for 8-12 hours. Step S1.3: Add AMPS to the solution in step 1.2 to form a third mixing system, then heat to 38-45°C and continue to rotate for 1-2 hours. Add APS and continue to rotate for 0.5-1 hour. Remove the leather and air dry to obtain tanned leather.

5. The preparation method of the biomass-based pn-type dual-drive evaporation power generation device as described in claim 4, characterized in that, In step S1.1, the pH value of the first mixing system is 4.2 to 4.8; the salt is sodium chloride, ammonium chloride or magnesium sulfate; the acid is formic acid, lactic acid or oxalic acid; the raw hide is sheepskin, cowhide or pigskin; the system temperature is 20 to 25°C during rotation; and the rotation time is 0.5 to 1 hour.

6. The preparation method of the biomass-based pn-type dual-drive evaporation power generation device as described in claim 4, characterized in that, In step S1.2, the vegetable tanning agent is tannin of mandarin orange or tannin of bayberry; the added alkali is Na2CO3 or NaHCO3.

7. The preparation method of the biomass-based pn-type dual-drive evaporation power generation device as described in claim 3, characterized in that, In step S3, specifically: Step S3.1: Mix the wood with alkaline solution and stir magnetically for 4-8 hours. Then adjust the pH of the solution to 12 and perform lignin removal treatment. After washing several times with distilled water, pre-freeze for more than 12 hours and freeze-dry to obtain lignin-removed wood. Step S3.2: Mix the lignin-free wood with CHPTAC and perform ammonium modification for 4-8 hours. Then wash it several times with distilled water, pre-freeze it for more than 12 hours, and freeze-dry it to obtain a positively charged wood substrate.

8. The preparation method of the biomass-based pn-type dual-drive evaporation power generation device as described in claim 7, characterized in that, In step S3.1, the freeze-drying temperature is -50 to -60°C and the freeze-drying time is 24 to 48 hours. The alkaline solution is a mixture of NaOH, Na2SO3 and water, and the mass ratio of NaOH, Na2SO3 and water is 100 to 200: 50 to 100: 850 to 1700.

9. The preparation method of the biomass-based pn-type dual-drive evaporation power generation device as described in claim 7, characterized in that, In step S3.2, the wood is balsa wood or balsa wood.

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