Photo-thermal-electric-thermal synergistic evaporator and preparation method thereof

Abstract

The invention belongs to the technical field of seawater desalination, and discloses a light-heat-electricity-heat synergistic evaporator and a preparation method thereof.The light-heat-electricity-heat synergistic evaporator comprises a water transmission channel, a light-heat evaporation interface and an electric heating evaporation interface, the light-heat evaporation interface is arranged on the water transmission channel, and the electric heating evaporation interface is arranged in the light-heat evaporation interface; the water transmission channel is made of a two-dimensional layered material, the photo-thermal evaporation interface is made of a two-dimensional layered material composite surface plasmon material, and the electric heating evaporation interface comprises a metal net which is arranged in the photo-thermal evaporation interface and forms an interlayer heating structure. Compared with a traditional photo-thermal evaporator, the photo-thermal-electric-thermal synergistic evaporator adopting an interlayer heating mode can achieve all-weather stable operation through solar energy and electric energy, and the heat loss of electric heating is reduced by regulating and controlling the position of an electric heating evaporation interface. Due to the high conductivity of the metal net, the evaporation efficiency is greatly improved, and the metal net can be efficiently applied to industrial production of water evaporation, seawater desalination and fresh water production.

Description

Technical Field

[0001] The invention relates to a photothermal and electrothermal cooperative evaporator and a preparation method thereof, and belongs to the technical field of seawater desalination. Background Art

[0002] Converting seawater into fresh water can effectively alleviate the crisis of fresh water shortage. Traditional commercial seawater desalination technologies, such as reverse osmosis, multi-stage flash evaporation, low-temperature multi-effect distillation, etc., have the disadvantages of large footprint, high energy consumption, high equipment cost, and difficulty in portability.

[0003] Solar-driven interfacial evaporation technology uses the photothermal effect of green solar energy to evaporate and condense salt water to obtain fresh water. The structure of the solar evaporator consists of two parts: a photothermal evaporation interface and a transmission channel. The photothermal evaporation interface is composed of materials with high photothermal conversion capabilities, and the transmission channel is composed of a porous matrix with good mass transfer performance and good thermal insulation. When sunlight shines on the evaporation interface, the salt water is transported upward to the evaporation interface through the transmission channel. The evaporation interface converts solar energy into thermal energy and drives the salt water to undergo phase change, condensing and collecting fresh water. The current solar desalination technology can only desalinate salt water when there is sufficient light, but the evaporation performance is very low when there is insufficient light. How to improve the evaporation performance when there is insufficient light and design a solar evaporator that can desalinate seawater around the clock is the current challenge.

[0004] By introducing electric heat into the solar evaporator and using electric heat to supplement the evaporation performance under insufficient light conditions, all-weather seawater desalination can be achieved. However, the traditional electric evaporator has a low evaporation rate at low voltage, and salt crystallization at the evaporation interface leads to low evaporation performance. In addition, the traditional photothermal-electrical co-evaporator still requires a higher input voltage, and applying a high voltage to improve performance will result in poor safety and rapid equipment loss. Summary of the invention

[0005] The object of the present invention is to provide a photothermal and electrothermal cooperative evaporator and a preparation method thereof, which can realize all-weather evaporation with low voltage and high evaporation rate.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: In a first aspect, the present invention provides a photothermal and electrothermal cooperative evaporator, comprising a water transmission channel, a photothermal evaporation interface and an electrothermal evaporation interface, the photothermal evaporation interface being arranged on the water transmission channel, the electrothermal evaporation interface being arranged in the photothermal evaporation interface, the water transmission channel being made of a two-dimensional layered material, the photothermal evaporation interface being made of a two-dimensional layered material composite surface plasmon material, and the electrothermal evaporation interface comprising a metal mesh arranged in the photothermal evaporation interface to form an interlayer heating structure.

[0007] In combination with the first aspect, further, the water transmission channel is made of reduced graphene oxide, the photothermal evaporation interface is made of reduced graphene oxide composite tungsten carbide, and the electrothermal evaporation interface includes a titanium mesh arranged in the photothermal evaporation interface to form an interlayer heating structure.

[0008] In combination with the first aspect, further, in the reduced graphene oxide composite tungsten carbide, the mass ratio of reduced graphene oxide to tungsten carbide is 1:0.001 to 1:3.

[0009] In combination with the first aspect, further, in the reduced graphene oxide composite tungsten carbide, the mass ratio of reduced graphene oxide to tungsten carbide is 1:2.

[0010] In combination with the first aspect, further, the metal mesh is arranged in the middle of the photothermal evaporation interface.

[0011] In combination with the first aspect, further, the input voltage of the evaporator is 1.5V.

[0012] In a second aspect, the present invention provides a method for preparing a photothermal and electrothermal synergistic evaporator, comprising: preparing reduced graphene oxide ink and reduced graphene oxide composite tungsten carbide ink; 3D printing using reduced graphene oxide ink to obtain water transport channels; 3D printing is performed on the water transmission channel using reduced graphene oxide composite tungsten carbide ink to obtain a photothermal evaporation interface, and in the process of printing the photothermal evaporation interface, a titanium mesh is fixed in the photothermal evaporation interface to form an interlayer heating structure; The printed water transmission channel and photothermal evaporation interface are frozen, freeze-dried and annealed to obtain a photothermal and electrothermal synergistic evaporator with a multi-level porous structure.

[0013] In combination with the second aspect, further, preparing reduced graphene oxide ink and reduced graphene oxide composite tungsten carbide ink includes: Concentrated sulfuric acid and nitric acid are added to the graphite sheet for acidification and exfoliation, and after stirring, the sheet is washed with deionized water, filtered, dried and annealed to obtain expanded graphite powder; Potassium persulfate, phosphorus pentoxide and concentrated sulfuric acid are added to the expanded graphite powder for water bath heating, and after stirring, the powder is washed with deionized water, filtered and dried to obtain pretreated graphite powder; Potassium permanganate and concentrated sulfuric acid are added to the pretreated graphite powder, and the mixture is reduced with an ascorbic acid solution to obtain a reduced graphene oxide aqueous solution, which is filtered through a circulating water vacuum pump to obtain a reduced graphene oxide ink; Tungsten carbide nanoparticles are doped into reduced graphene oxide ink and homogenized to obtain reduced graphene oxide composite tungsten carbide ink.

[0014] In combination with the second aspect, further, in the reduced graphene oxide composite tungsten carbide ink, the mass ratio of reduced graphene oxide to tungsten carbide is 1:0.001 to 1:3.

[0015] In combination with the second aspect, further, in the reduced graphene oxide composite tungsten carbide ink, the mass ratio of reduced graphene oxide to tungsten carbide is 1:2.

[0016] In combination with the second aspect, further, the titanium mesh is arranged in the middle of the photothermal evaporation interface.

[0017] In a third aspect, the present invention provides a photothermal-electrical co-evaporator as described in any one of the first aspects or a photothermal-electrical co-evaporator prepared by the preparation method of the photothermal-electrical co-evaporator as described in any one of the second aspects, and its application in water evaporation, seawater desalination or fresh water production.

[0018] In a fourth aspect, the present invention provides a photothermal and electrothermal synergistic seawater desalination method, wherein a photothermal and electrothermal synergistic evaporator as described in any one of the first aspects or a photothermal and electrothermal synergistic evaporator prepared by the photothermal and electrothermal synergistic evaporator preparation method as described in any one of the second aspects is placed in seawater, and seawater is desalinated by converting solar energy into thermal energy through a photothermal evaporation interface, and / or by using Joule heat provided by the electrothermal evaporation interface.

[0019] In combination with the fourth aspect, further, the input voltage of the evaporator is 1.5V.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The photothermal and electrothermal synergistic evaporator provided by the present invention is composed of a transmission channel made of a two-dimensional layered material, a photothermal evaporation interface made of a two-dimensional layered material loaded with a plasmon material, and a metal mesh as an electrothermal evaporation interface. Compared with the traditional photothermal evaporator, the photothermal and electrothermal synergistic evaporator adopts an interlayer heating mode and uses solar energy and electric energy to achieve stable operation around the clock. Due to the unique electrothermal interlayer heating design, the heat loss of the electric heat is reduced by regulating the position of the electrothermal evaporation interface. Due to the high conductivity of the titanium mesh, the evaporation rate of the evaporator can reach 50.08kg·m by simply inputting a voltage of 1.5V. -2 ·h -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of a photothermal and electrothermal synergistic evaporator with an interlayer heating mode provided by an embodiment of the present invention; Figure 2Schematic diagram of rheological properties of different rGO-WC inks provided in an embodiment of the present invention, wherein a represents the change of viscosity of rGO-WC inks with different WC mass ratios with shear rate, and b represents the change of storage modulus G′ and loss modulus G′′ of rGO-WC inks with different WC mass ratios with shear stress; Figure 3 is the XRD spectrum of rGO and rGO-WC provided in the embodiments of the present invention; Figure 4 The rGO-WC (m rGO :m WC =1:2) Schematic diagram of pore size distribution of photothermal evaporation interface; Figure 5 : is a graph comparing the hydrophilicity changes of the rGO transmission channel and the rGO-WC evaporation interface before and after oxygen plasma treatment provided by an embodiment of the present invention, wherein a represents the rGO water transmission channel, and b represents the water contact angle of the rGO-WC evaporation interface before and after oxygen plasma treatment; Figure 6 Schematic diagrams of evaporators with electrothermal evaporation interfaces located at different positions provided by embodiments of the present invention, wherein (a) indicates that the electrothermal evaporation interface is at the top, (b) indicates that the electrothermal evaporation interface is in the middle, and (c) indicates that the electrothermal evaporation interface is at the bottom; Figure 7 The different evaporation interfaces provided by the embodiments of the present invention are subjected to 1 kW·m -2 Schematic diagram of surface temperature test under light intensity, where (a) shows the evaporation interface of dry planar rGO, planar rGO-WC, and grid rGO-WC at 1 kW·m without titanium mesh. -2 Temperature test under light intensity, (b) represents the temperature test of the electrothermal evaporation interface of a single titanium mesh at a voltage of 0.5V. DETAILED DESCRIPTION

[0022] The technical solution of the present application is further described in detail below in conjunction with specific implementation methods.

[0023] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limitations on the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments may be combined with each other.

[0024] The present application embodiment provides a photothermal and electrothermal synergistic evaporator, such as Figure 1As shown in the figure, it consists of three parts: photothermal evaporation interface (PEI), electrothermal evaporation interface (EEI) and water transport channel (TC). When there is sufficient light, the photothermal evaporation interface converts solar energy into thermal energy for seawater desalination. When there is insufficient light, the Joule heat provided by the electrothermal evaporation interface is used for seawater desalination to achieve all-weather seawater desalination. In the case of fresh water shortage, photoelectric coupling can also be used to achieve a faster water production rate to meet the urgent demand for fresh water.

[0025] The traditional solar interface evaporator has insufficient performance when the light is insufficient, so electric heating is used to supplement the performance when the light is insufficient. However, the traditional electric thermal evaporator has poor performance at low pressure, and the actual high voltage performance improvement will produce the disadvantages of poor safety factor and easy device wear. Therefore, this embodiment designs an interlayer structure photothermal and electrothermal co-evaporator that can obtain high performance at low pressure. The design of the grid-like photothermal evaporation interface and the interlayer structure respectively improves the photothermal evaporation efficiency and the electrothermal evaporation efficiency, realizes all-weather seawater desalination, and can produce a large amount of fresh water in a short time through photoelectric coupling under the condition of fresh water shortage to meet the urgent fresh water demand. The macroporous microstructure and super hydrophilicity of the evaporator ensure the long-term salt resistance of the device at a high evaporation rate, which provides a reference for the design of photothermal and electrothermal co-evaporators.

[0026] The photothermal and electrothermal synergistic evaporator provided in this embodiment is prepared by 3D printing technology. Among them, the photothermal evaporation interface is prepared by reduced graphene oxide ink composite tungsten carbide nanoparticles (tungsten carbidenanoparticles, WC NPs), and the transmission channel is prepared by reduced graphene oxide (reduced graphene oxide, rGO) ink. Reduced graphene oxide-tungsten carbide (rGO-WC) photothermal evaporation interface and rGO water transmission channel are prepared by ink direct writing 3D printing technology. The printed sample is placed in a -80℃ refrigerator for 2h, freeze-dried for 24h, and annealed to construct an evaporator with a multi-level porous structure, which is physically combined with a commercially available titanium mesh to form a photothermal and electrothermal synergistic evaporator with an interlayer heating mode.

[0027] WC was added to the rGO ink, and the mass ratio of rGO to WC was 1:0 (i.e., without WC, or 1:0.001), 1:1, 1:2, and 1:3, respectively, to obtain different rGO-WC inks. The rheological properties of the ink were tested using a rotational rheometer, such as Figure 2As shown, the experiments prove that all inks exhibit excellent shear thinning properties and high modulus, and can be smoothly extruded from the needle under a certain pressure and maintain a certain shape.

[0028] The rGO water transport channel and the rGO-WC photothermal evaporation interface formed after doping with different WC mass ratios were characterized by scanning electron microscopy (SEM). The rGO water transport channel prepared by printing rGO ink using ink direct writing 3D printing technology has a macroporous structure. And the rGO-WC formed by doping with different WC mass ratios does not destroy this macroporous structure. WC is uniformly loaded on the wall of rGO, which is conducive to reducing the mass transfer resistance of high-concentration brine at the photothermal evaporation interface to the transport channel.

[0029] Samples with different macrostructures were prepared by adjusting the printing program of the 3D printer. First, planar rGO (size 16mm×16mm, thickness 1mm) was prepared using rGO ink as the raw material; then, two structures were prepared using rGO-WC ink: one was planar rGO-WC (size 16mm×16mm, thickness 1mm), and the other was grid rGO-WC (size 16mm×16mm, height 6.5mm, grid side length 2mm).

[0030] In order to explore the light absorption capacity of the photothermal evaporation interface, the reflectivity and transmittance of the rGO-WC evaporation interface with different WC mass ratios without the titanium mesh were tested using a UV-Vis-NIR spectrophotometer, and the absorptivity was calculated. The absorptivity of the planar rGO-WC evaporation interface and the grid rGO-WC evaporation interface with different WC mass ratios in the wet state is shown in Table 1.

[0031] Table 1 Absorption rate of planar rGO-WC evaporation interface and grid rGO-WC evaporation interface in wet state with different WC mass ratios

[0032] As shown in Table 1, in the wet state, the planar rGO-WC photothermal evaporation interface with a mass ratio of rGO to WC of 1:0 (i.e., no WC doping, or 1:0.001), 1:1, 1:2, and 1:3 has a solar absorptivity of 96.55%, 96.78%, 97.32%, and 97.44% at 300nm to 2500nm, respectively. With the increase of WC content, the light absorptivity of the planar rGO-WC increases. When the ratio of rGO to WC is 1:2, the solar light absorption reaches an equilibrium point of 97.32%. Therefore, a grid-like rGO-WC photothermal evaporation interface was further constructed using this ratio of ink. Due to the localized surface plasmon resonance effect of WC and the anti-reflection effect of the grid macrostructure, the solar absorptivity is as high as 97.82%, which proves that the grid-like photothermal evaporation interface constructed by 3D printing has excellent light absorption performance.

[0033] like Figure 3 As shown, the X-ray diffraction (XRD) pattern shows that rGO-WC (m rGO :m WC =1:2) is consistent with the standard diffraction card of WC (JCPDS No.42-0853), indicating that WC was successfully introduced through 3D printing technology.

[0034] like Figure 4 As shown in the figure, the pore size distribution of rGO-WC samples was investigated and it was found that rGO-WC (m rGO :m WC =1:2) is mainly distributed between 30μm and 120μm, showing a macroporous microstructure. This macroporous structure ensures that the high-concentration brine at the evaporation interface can be quickly transferred to the evaporating water body, and the crystallization of salt at the evaporation interface can be effectively avoided at a high evaporation rate.

[0035] Since the rGO-WC photothermal evaporation interface and rGO water transport channel obtained after annealing are hydrophobic, they are treated with oxygen plasma to improve their hydrophilicity, and the contact angle test is used to characterize the difference in hydrophilicity of the rGO water transport channel and rGO-WC photothermal evaporation interface before and after surface treatment. Figure 5 As shown in the figure, the results show that after oxygen plasma treatment, the rGO water transport channel and the rGO-WC photothermal evaporation interface can completely absorb water droplets within 59.2ms, showing superhydrophilicity. Superhydrophilicity also ensures that the solar evaporator has high mass transfer capacity to achieve stable salt-tolerant evaporation at high evaporation rates.

[0036] A commercially available titanium mesh was used as the electrothermal evaporation interface. The structure of the titanium mesh was characterized by scanning electron microscopy, and it was found that the titanium mesh had a hollow structure with a mesh side length of 220μm. This larger mesh would not affect the mass transfer between the photothermal evaporation interface and the transmission channel.

[0037] In order to explore the photothermal conversion capacity of different photothermal evaporation interfaces, the planar rGO evaporation interface without titanium mesh, the planar rGO-WC evaporation interface and the grid rGO-WC evaporation interface were compared under the conditions of 1 kW·m -2 Surface temperature under light intensity. When no titanium mesh is set, the evaporation interface of dry planar rGO, planar rGO-WC, and grid rGO-WC is 1kW·m -2 The temperature under light intensity and the temperature of the electrothermal evaporation interface of the titanium mesh alone at a voltage of 0.5 V are shown in Table 2. The test method is as follows Figure 7 shown.

[0038] Table 2 Evaporation interface of dry planar rGO, planar rGO-WC, and grid rGO-WC at 1 kW·m without titanium mesh -2 Temperature under light intensity and temperature table of single titanium mesh electrothermal evaporation interface at 0.5V voltage

[0039] It can be seen from Table 2 that when no titanium mesh is set, the evaporation interface of dry planar rGO, planar rGO-WC, and grid rGO-WC is 1kW·m -2 The temperatures under light intensity were 49.1℃, 55.5℃, and 63.1℃, respectively. The results show that the mesh rGO-WC interface has excellent light-to-heat conversion performance. In addition, the electrothermal performance of the commercially available titanium mesh was investigated, and it was found that it could reach 60.1℃ within 1 minute at a low voltage of 0.5V, indicating that the titanium mesh has excellent Joule heating performance and fast electrothermal response.

[0040] The planar rGO evaporation interface without titanium mesh, the planar rGO-WC evaporation interface, and the grid-like rGO-WC evaporation interface were combined with the rGO water transmission channel to form a photothermal evaporator, as shown in Table 3. -2 The evaporation rates under different light intensities were 1.36 kg·m -2 ·h -1 , 1.46kg·m -2 ·h -1 and 2.31 kg·m -2 ·h -1 This proves that the solar evaporator with a three-dimensional grid-like rGO-WC evaporation interface has the highest evaporation rate under the same conditions.

[0041] Table 3 Evaporators with planar rGO, planar rGO-WC, and grid rGO-WC evaporation interfaces at 1 kW·m -2 Evaporation rate table under light intensity

[0042] like Figure 6 As shown, in order to explore the effect of the electrothermal evaporation interface at different positions on the electrothermal evaporation performance, three evaporator structures were designed, namely, the titanium mesh was above the grid-like rGO-WC photothermal evaporation interface (titanium mesh on top), in the middle of the grid-like rGO-WC photothermal evaporation interface (titanium mesh in the middle), and below the grid-like rGO-WC photothermal evaporation interface (titanium mesh on the bottom). The temperature and evaporation rate of the three structures at a voltage of 0.5 V were tested. The evaporation rates of the evaporators with the electrothermal evaporation interface at different positions at a voltage of 0.5 V are shown in Table 4.

[0043] Table 4 Evaporation rate of the evaporator with the electrothermal evaporation interface at different positions at a voltage of 0.5 V

[0044] As shown in Table 4, the evaporation rate and surface temperature of the titanium mesh in the interlayer heating mode are the highest. Most of the heat of the titanium mesh above is lost to the environment, while most of the heat of the titanium mesh below is lost to the evaporating water. The interlayer heating mode of the titanium mesh in the middle can minimize heat loss and thus has the highest interface temperature. This design transfers the heat generated by electrothermal heating to the grid and relies on the large surface area of ​​the grid rGO-WC to improve the evaporation performance.

[0045] In order to explore the electrothermal evaporation performance of the photothermal-electrothermal evaporator with interlayer heating mode, voltages of 0.5 V, 0.75 V, 1 V, 1.25 V, and 1.5 V were applied to the evaporator. As shown in Table 5, the evaporation rates were 2.95 kg·m -2 ·h -1 , 7.34kg·m -2 ·h -1 、15.82kg·m -2 ·h -1 、28.61kg·m -2 ·h -1 and 50.08kg·m -2 ·h -1 As shown in Table 6, the evaporation rate per unit voltage at 1.5 V far exceeds that of the electric evaporators reported in other literatures.

[0046] Table 5 The electrothermal evaporation rate of the photothermal-electrothermal evaporator with interlayer heating mode at different voltages

[0047] Table 6 Comparison of evaporation rates of photothermal and electrothermal evaporators with interlayer heating mode and other electrothermal evaporators

[0048] Other literature, for example: Journal Nano Energy 2024, 130, 110057 uses electric heating to achieve all-weather interface seawater desalination, using PAAm hydrogel as a transmission channel, CNTs carbon nanotubes as photothermal materials loaded at the interface of the hydrogel as a photothermal evaporation interface, and embedding a commercially available electric heating mesh into the hydrogel as an electrothermal evaporation interface. -2 +1.7V photoelectric coupling condition can reach 16.83kg·m -2 ·h -1 evaporation performance.

[0049] Journal Nano Energy 2021, 81, 105682 A graphene oxide solution was coated on a silane sponge to obtain an all-weather evaporator with a Janus structure. The evaporator has a high efficiency of 1 kW·m -2 The light intensity can reach 1.61kg·m -2 ·h -1 The evaporation rate can reach 6.53 kg·m when coupled with a 5V voltage. -2 ·h -1 evaporation rate.

[0050] Journal Adv.Sci.2024,11,2400623 Tencel was woven into an evaporation interface, and a highly conductive wire was mixed inside as an electric heating material. Polypyrrole was loaded on the fabric as a photothermal material to construct an evaporator. -2 The light intensity and 3V voltage coupling can reach 5.57kg·m -2 ·h -1 evaporation rate.

[0051] The photothermal-electrothermal evaporator with interlayer heating mode can achieve a higher evaporation rate under the condition of photoelectric coupling. When a voltage of 1.5 V and 1, 5, 10, 15 and 20 kW·m are applied simultaneously, the evaporation rate is 100%. -2 Under the light intensity of 52.60kg·m -2 ·h -1 、62.94kg·m -2 ·h -1 、74.21kg·m -2 ·h -1 、86.08kg·m -2 ·h -1 and 100.01kg·m -2 ·h -1 The evaporation rate shows excellent evaporation performance.

[0052] The photothermal and electrothermal evaporator with interlayer heating mode was tested by applying 1.5 V voltage and 20 kW·m -2The water production performance test was carried out under a light intensity of 10 hours. The results showed that the evaporator can reach 99.85kg·m -2 ·h -1 Ultra-high evaporation rate and 64.10L·m -2 ·h -1 The collected fresh water meets the drinking water standards of the World Health Organization. In addition, during the 10-hour test period, no salt crystals appeared on the evaporation interface of the evaporator, proving that this photothermal-electrical-thermal evaporator with interlayer heating mode has excellent stability under the condition of ultra-high evaporation rate, which can not only realize all-weather seawater desalination, but also achieve ultra-fast water production under the condition of fresh water shortage to meet the urgent demand for fresh water.

[0053] In order to further explore the water production stability of the photothermal and electrothermal evaporator with interlayer heating mode under outdoor conditions, a high water production rate was obtained by optical focusing using a Fresnel lens when there was sufficient light, and a high water production rate was also obtained by using electric heating when there was insufficient light. The 24-hour water production stability results showed that the evaporator could maintain 45.83 kg·m -2 ·h -1 The evaporation rate and 34.04 L·m -2 ·h -1 The water production rate is high, showing a high water production rate. This photothermal and electrothermal synergistic evaporator with interlayer heating mode provides a new idea for the design and practical application of all-weather evaporators in the future.

[0054] The present application provides a method for preparing a photothermal and electrothermal synergistic evaporator, comprising: preparing reduced graphene oxide ink and reduced graphene oxide composite tungsten carbide ink; 3D printing using reduced graphene oxide ink to obtain water transport channels; 3D printing is performed on the water transmission channel using reduced graphene oxide composite tungsten carbide ink to obtain a photothermal evaporation interface, and in the process of printing the photothermal evaporation interface, a titanium mesh is fixed in the photothermal evaporation interface to form an interlayer heating structure; The printed water transmission channel and photothermal evaporation interface are frozen, freeze-dried and annealed to obtain a photothermal and electrothermal synergistic evaporator with a multi-level porous structure.

[0055] In this embodiment, the preparation of reduced graphene oxide ink and reduced graphene oxide composite tungsten carbide ink includes: Concentrated sulfuric acid and nitric acid are added to the graphite sheet for acidification and exfoliation, and after stirring, the sheet is washed with deionized water, filtered, dried and annealed to obtain expanded graphite powder; Potassium persulfate, phosphorus pentoxide and concentrated sulfuric acid are added to the expanded graphite powder for water bath heating, and after stirring, the powder is washed with deionized water, filtered and dried to obtain pretreated graphite powder; Potassium permanganate and concentrated sulfuric acid are added to the pretreated graphite powder, and the mixture is reduced with an ascorbic acid solution to obtain a reduced graphene oxide aqueous solution, which is filtered through a circulating water vacuum pump to obtain a reduced graphene oxide ink; Tungsten carbide nanoparticles are doped into reduced graphene oxide ink and homogenized to obtain reduced graphene oxide composite tungsten carbide ink.

[0056] Experimental methods: Materials: Graphite sheets (XF049, 50 mesh) were purchased from XFNANO. Concentrated H2SO4 (98%), HNO3 (68%), and HCl (36%) were purchased from Huasheng Special Products Co., Ltd. NaOH, KMnO4, P2O5, H2O2 (30%) solution, K2S2O8, and NaCl were purchased from Sinopharm Chemical Reagent. L-Ascorbic acid was purchased from Sigma Aldrich. WC was purchased from Shanghai Yuanye Biotechnology Co., Ltd. The mesh density of the titanium mesh was 60 mesh, and the side length of a single mesh was 0.28 mm.

[0057] Preparation of rGO ink: To 1 g of graphite sheet, 30 mL of concentrated H2SO4 and 10 mL of HNO3 were added in a volume ratio of 3:1 for acid exfoliation. After stirring for 24 h, the expanded graphite powder was washed with deionized water, filtered, dried, and annealed at 1000 ° C. To 1 g of expanded graphite powder, 0.84 g of K2S2O8, 1.24 g of P2O5 and 60 mL of concentrated H2SO4 were added, heated in a water bath at 80 ° C and stirred for 5 h. After washing with deionized water, filtered, dried, and annealed at 1000 ° C, the expanded graphite powder was obtained. After drying, pretreated graphite powder was obtained. 3 g of KMnO4 and 40 mL of concentrated H2SO4 were added to 1 g of pretreated graphite powder. The mixture was heated in a water bath at 35 °C for 2 h. The reaction solution was transferred to a centrifuge tube. 1 M hydrochloric acid and deionized water were added successively for centrifugation. The precipitate was collected and added with 1 L of deionized water for stirring for 12 h. Impurities were removed by centrifugation (5000 rpm) to obtain a graphene oxide (GO) solution. Ascorbic acid solution (80 mg mL -1 ) The GO solution was reduced at 70°C to obtain a reduced graphene oxide (rGO) aqueous solution. After most of the water was filtered out by a circulating water vacuum pump, an rGO ink with a solid content of 1% to 2% of rGO was obtained.

[0058] Preparation of rGO-WC ink: rGO-WC ink was prepared by doping rGO ink with WC nanoparticles at different mass ratios, and the solid content mass ratio of rGO to WC nanoparticles was 1:1, 1:2 and 1:3. All inks were homogenized using a homogenizer after doping.

[0059] Preparation of evaporator: The solar evaporator is prepared by direct writing 3D printing technology, which can be operated in three directions: x-axis, y-axis and z-axis. When preparing the solar evaporator, the diameter of the 3D printing needle is 500μm, the operating pressure is 200kPa to 250kPa, the needle movement speed is 35mm / s, and the target pattern is printed on a glass slide in the air. The printed original evaporator needs to be freeze-dried for 24 hours and then annealed in a nitrogen atmosphere at 200℃ for 30 minutes. Finally, the solar evaporator needs to be treated with oxygen plasma. The rGO-WC photothermal evaporation interface and rGO water transmission channel can be obtained by treating it at a power of 100W for 5 minutes. The purchased titanium mesh is cut, coated with silver paste and solidified, and then formed with the photothermal evaporation interface and transmission channel to form a photothermal and electrothermal synergistic evaporator with an interlayer heating mode.

[0060] Characterization: The rheological properties of different inks were measured using a rotational rheometer (HAAKE MARS 40). The rheological properties of different rGO-WC inks are shown in Figure 2. Figure 2 As shown. The lattice fringes of the samples were observed by scanning electron microscopy (Zeiss SUPRA 55) and transmission electron microscopy (Talos F200X). The porosity and pore size distribution were measured by a mercury porosimeter (AutoPore Iv 9510). The XRD patterns were tested on a PANalytical X-ray diffractometer (Empyrean). The reflection, transmission and absorption spectra were measured by a UV-VIS spectrometer (Lambda 950) equipped with an integrating sphere (PerkinElmer). The wettability of the solar evaporator was characterized by a contact angle meter (datphysics OCA). The temperature of the solar evaporator was detected by an infrared camera (288S, FOTRIC).

[0061] Measurements of solar evaporation experiments: Xenon lamp (EOS-150) and xenon lamp (HSX-F300) were used as solar simulators to test the performance of indoor solar desalination under different light intensities. An optical power density meter (CEL-NP2000) was used to calibrate the light intensity. The solar evaporator was embedded in a mold printed by a light-curing 3D printer (Saturn 3 Ultra) and placed in a volumetric flask to isolate the interference of surrounding evaporation. An analytical balance (OHRUS PR124ZH / E) was used to monitor mass changes. During the solar evaporation process, the indoor temperature was maintained at 20℃ to 25℃ and the humidity was maintained at 60% to 70%.

[0062] Measurements of electrothermal evaporation experiments: MP3030D four-dimensional display DC power supply was used to test the indoor and outdoor evaporation and water production performance under different voltages. The evaporator was embedded in a mold printed by a light-curing 3D printer (Saturn 3 Ultra) and placed in a volumetric flask to isolate the interference of surrounding evaporation. The two ends of the titanium mesh and the DC power supply were connected by a power cord consisting of an iron-plated nickel electrode clip and a copper wire. An analytical balance (OHRUS PR124ZH / E) was used to test the mass change of the water body before and after evaporation to calculate the evaporation rate. During the electrothermal evaporation experiment measurement, the indoor temperature was maintained at 20℃ to 25℃ and the humidity was maintained at 60% to 70%.

[0063] The embodiments of the present application provide an application of a photothermal-electrical co-evaporator such as the photothermal-electrical co-evaporator in any embodiment of the present application or a photothermal-electrical co-evaporator prepared by the preparation method of the photothermal-electrical co-evaporator in any embodiment in water evaporation or seawater desalination or fresh water production.

[0064] The photothermal and electrothermal synergistic evaporator provided in any embodiment of the present application can desalinate water sources such as seawater, lake water, and river water to collect fresh water. When there is sufficient sunlight, the photothermal effect of solar energy can be used to evaporate the water source and then condense it to collect fresh water; on cloudy days, rainy days, or at night when the light is weak, Joule heat can be used to evaporate the water source and condense it to collect fresh water. More importantly, in the case of extremely urgent fresh water resources, when there is sufficient sunlight, the photothermal effect of solar energy and Joule heat can be used simultaneously to produce desalination, thereby achieving higher water production performance.

[0065] An embodiment of the present application provides a photothermal and electrothermal synergistic seawater desalination method, wherein a photothermal and electrothermal synergistic evaporator as in any embodiment of the present application or a photothermal and electrothermal synergistic evaporator prepared by the method for preparing a photothermal and electrothermal synergistic evaporator as in any embodiment of the present application is placed in seawater, and seawater is desalinated by converting solar energy into thermal energy through a photothermal evaporation interface, and / or by using Joule heat provided by an electrothermal evaporation interface.

[0066] The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A photothermal and electrothermal synergistic evaporator, characterized in that: It includes a water transmission channel, a photothermal evaporation interface and an electrothermal evaporation interface. The photothermal evaporation interface is arranged on the water transmission channel, and the electrothermal evaporation interface is arranged in the photothermal evaporation interface. The water transmission channel is made of a two-dimensional layered material, the photothermal evaporation interface is made of a two-dimensional layered material composite surface plasmon material, and the electrothermal evaporation interface includes a metal mesh arranged in the photothermal evaporation interface to form an interlayer heating structure.

2. The photothermal and electrothermal synergistic evaporator according to claim 1, characterized in that: The water transmission channel is made of reduced graphene oxide, the photothermal evaporation interface is made of reduced graphene oxide composite tungsten carbide, and the electrothermal evaporation interface includes a titanium mesh arranged in the photothermal evaporation interface to form an interlayer heating structure.

3. The photothermal and electrothermal synergistic evaporator according to claim 2, characterized in that: In the reduced graphene oxide composite tungsten carbide, the mass ratio of reduced graphene oxide to tungsten carbide is 1:0.001 to 1:

3.

4. The photothermal and electrothermal synergistic evaporator according to claim 2, characterized in that: In the reduced graphene oxide composite tungsten carbide, the mass ratio of reduced graphene oxide to tungsten carbide is 1:

2.

5. The photothermal and electrothermal evaporator according to claim 1, characterized in that: The metal mesh is arranged in the middle of the photothermal evaporation interface.

6. The photothermal and electrothermal synergistic evaporator according to claim 1, characterized in that: The input voltage to the evaporator is 1.5V.

7. A method for preparing a photothermal and electrothermal synergistic evaporator, characterized in that: include: preparing reduced graphene oxide ink and reduced graphene oxide composite tungsten carbide ink; 3D printing using reduced graphene oxide ink to obtain water transport channels; 3D printing is performed on the water transmission channel using reduced graphene oxide composite tungsten carbide ink to obtain a photothermal evaporation interface, and in the process of printing the photothermal evaporation interface, a titanium mesh is fixed in the photothermal evaporation interface to form an interlayer heating structure; The printed water transmission channel and photothermal evaporation interface are frozen, freeze-dried and annealed to obtain a photothermal and electrothermal synergistic evaporator with a multi-level porous structure.

8. The method for preparing a photothermal and electrothermal synergistic evaporator according to claim 7, characterized in that: The preparation of reduced graphene oxide ink and reduced graphene oxide composite tungsten carbide ink comprises: Concentrated sulfuric acid and nitric acid are added to the graphite sheet for acidification and exfoliation, and after stirring, the sheet is washed with deionized water, filtered, dried and annealed to obtain expanded graphite powder; Potassium persulfate, phosphorus pentoxide and concentrated sulfuric acid are added to the expanded graphite powder for water bath heating, and after stirring, the powder is washed with deionized water, filtered and dried to obtain pretreated graphite powder; Potassium permanganate and concentrated sulfuric acid are added to the pretreated graphite powder, and the mixture is reduced with an ascorbic acid solution to obtain a reduced graphene oxide aqueous solution, which is filtered through a circulating water vacuum pump to obtain a reduced graphene oxide ink; Tungsten carbide nanoparticles are doped into reduced graphene oxide ink and homogenized to obtain reduced graphene oxide composite tungsten carbide ink.

9. Use of the photothermal-electrical-thermal evaporator according to any one of claims 1 to 6 or the photothermal-electrical-thermal evaporator prepared by the preparation method of the photothermal-electrical-thermal evaporator according to any one of claims 7 to 8 in water evaporation, seawater desalination or fresh water production.

10. A method for synergistic desalination of seawater by combining light, heat and electricity, characterized in that: The photothermal-electrical co-evaporator as claimed in any one of claims 1 to 6 or the photothermal-electrical co-evaporator prepared by the method for preparing the photothermal-electrical co-evaporator as claimed in any one of claims 7 to 8 is placed in seawater, and seawater is desalinated by converting solar energy into thermal energy through a photothermal evaporation interface, and / or by using Joule heat provided by an electrothermal evaporation interface.

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