KR102154656B1 - Device for Simultaneous Production of Steam and Electricity - Google Patents

Abstract

The present invention relates to an apparatus for simultaneous production of steam and electricity, which can simultaneously produce steam and electricity without incorporating separate devices, and has a simple structure with excellent electricity production efficiency, and more particularly, a metal electrode as a first electrode. , A carbon structure layer deposited on a porous hydrophilic polymer substrate having a structure of a hollow cone, pyramid, truncated cone, or truncated pyramid is used as a second electrode, and the bottom of the hydrophilic polymer substrate is in contact with the water in which the first electrode is immersed. It relates to an apparatus for simultaneous production of steam and electricity, characterized in that it is used in a suspended state.

Description

Device for Simultaneous Production of Steam and Electricity}

The present invention relates to an apparatus for simultaneous production of steam and electricity having a simple structure capable of simultaneously producing steam and electricity without incorporating separate devices, and having excellent electricity production efficiency.

As traditional fossil energy is depleted and interest in environmental problems is growing, pollution-free renewable energy that acquires energy that is transformed or dissipated in nature and converts it into usable energy has been proposed as an efficient solution to the energy crisis. Examples of renewable energy sources include wind, solar, geothermal and water. Among them, solar energy is receiving the most attention due to its universal, clean, eco-friendly, and sustainable properties, and has been widely used for hydrogen production, power generation, photocatalysis, water purification, and desalination. Solar energy reaching the Earth's surface per year is about 2.85 million EJ, which is a vast energy source that is about 10,000 times the world's annual energy consumption. Nevertheless, the use of solar energy is still very limited. Water is a promising and attractive energy source that exists in a wide variety of rivers, lakes and seas as well as in our bodies. Conventionally, large and complex devices such as dams or waterwheels have been commonly used to harvest enormous energy from flowing water. However, they are not applicable for personal use or biomedical devices that require miniaturization or implantability. Therefore, developing a miniaturized, high-efficiency generator remains a challenge in the current water-based renewable energy field.

In 2001, Kral and Shapiro (Phys. Rev. Lett. 2001, 86, 131-134) proposed that current can be generated in metallic carbon nanotubes (CNTs) contained in flowing liquids through theoretical calculations. Later, in 2003, Sood et al. (Science 2003, 299, 1042-1044) found that voltage was induced in the sample along the flow direction of the liquid on the single-walled CNT bundle, and Guo et al. (Nat. Nanotechnol. 2014, 9, 378- 383) reported that a voltage of several mV is generated by the movement of droplets of seawater or ionic solution moving on a single-layered graphene piece in atmospheric conditions. Based on this, a nanogenerator based on macroscopically arranged CNT yarns, twisted and tensile polymer muscles, arranged multi-walled CNT sheets, superhydrophilic three-dimensional graphene oxide (GO) framework, and GO-metal nanohybrid materials, etc. ) Were developed. However, in order for the nanogenerators to generate electricity, not only requires separate energy and/or complex equipment to allow water to flow, but also increases the low current density caused by the problem of using a carbon material having low electrical conductivity. It has a fundamental problem that cannot be made. Therefore, these nanogenerators are suitable for producing very little power.

On the other hand, water evaporation is a very common and natural phenomenon of harvesting heat energy from the atmospheric environment. In energy harvesting equipment, steam production by evaporation of water has been used. Traditionally, fossil fuels were used to generate water vapor by heating a large amount of water in a steam engine, but recently, a solar-induced water vapor production system that produces water vapor from sunlight using a highly efficient absorber that converts sunlight into heat. This is attracting attention.

However, even if such a solar-induced steam production system is used, in order to obtain electricity from evaporation of water, a device that generates steam from sunlight must be integrated with a separate device for electricity production, and the amount of electricity obtained is also limited. For example, Ho et al. (Adv. Energy Mater. 2018, 1702149) used a ferroelectric fluoride polymer, polyvinylidene fluoride (PVDF), to harvest thermomechanical reactions from carbon sponge solar-evaporation. Ma et al. (Nano Energy 2016, 22, 19-26) reported a self-sufficient polymeric pyroelectric nanogenerator by water vapor without other energy devices. Zhou et al. (Adv. Energy Mater. 2018, 1702149) achieved a maximum photothermal efficiency of 75% at 1 sun irradiation by adopting a hybrid system based on a filter paper modified by CNT and a commercial Nafion membrane. The power of m2 was induced. Nevertheless, they have a problem that the system is complicated because two equipments must be combined. In addition, since the systems can generate water vapor only by light, they cannot produce electricity under dark conditions, or even if they are produced, the amount of electricity produced is relatively low.

On the other hand, metal air batteries using metals such as iron, zinc, and aluminum as a negative electrode, a cathode as a positive electrode, and oxygen in the air as a positive electrode active material are attracting attention as high energy density batteries. Metal-air batteries use cheap metal as a negative electrode, and use carbon and oxygen instead of metal oxides inside the battery, so their energy density is much higher than that of conventional secondary batteries, and their weight is light, so their practicality is high. It is known that the capacity of a lithium air battery among metal air batteries is 5 to 10 times that of a lithium ion battery. However, there is a problem that 1/3 of the charged electricity is lost due to heat, there is a risk factor due to an increase in electrode temperature, and the storage period of power is not long.

Phys. Rev. Lett. 2001, 86, 131-134 Science 2003, 299, 1042-1044 Nat. Nanotechnol. 2014, 9, 378-383 Adv. Energy Mater. 2018, 1702149 Nano Energy 2016, 22, 19-26 Adv. Energy Mater. 2018, 1702149

An object of the present invention is to provide an apparatus capable of efficiently producing water vapor and electricity simultaneously in one apparatus having a simple structure, even without combining two apparatuses.

The present invention for achieving the above object is a metal electrode as a first electrode, a carbon structure layer deposited on a porous hydrophilic polymer substrate having a hollow cone, pyramidal cone, truncated cone or pyramidal structure as a second electrode, It relates to an apparatus for simultaneous production of water vapor and electricity, characterized in that the first electrode is used in a suspended state by contacting the bottom surface of the hydrophilic polymer substrate with water in which the first electrode is immersed.

In the present specification, "upper part" of a cone or pyramid refers to the side of the carbon structure layer on the outer surface, and "lower part" refers to the side of the hydrophilic polymer substrate.

In addition, in this specification, the "apex angle" of the cone means the angle between the two lines forming the vertex of the cone at the vertex of the cone, and the "vertical angle" of the truncated cone means the angle between the two lines forming the virtual vertex of the truncated cone. do. The "vertical angle" of a pyramid is defined as the average value of the angle between the vertex and two adjacent sides on each bevel, and the "vertical angle" of the pyramid is defined as the average value of the angle between the two sides forming an imaginary vertex on each bevel.

In the present specification, the "bottom" of the polymer substrate refers to a cone (large) or a portion opposite to the (virtual) vertex of the pyramid (large).

The device of the present invention is used in a floating state in water, and is characterized in that it can simultaneously produce water vapor and electricity in one device without incorporating separate devices due to materials and structures. The apparatus of the present invention is a combination of a conventional solar-induced production system, a nano-generator, and a metal-air battery that generate electricity by moving droplets on a carbon structure. In the device of the present invention, when the light is not irradiated, current is mainly generated by the metal air battery, and under light irradiation, the generation of water vapor increases due to the light irradiation by the absorber, thereby increasing the rate of current generation of the nanogenerator.

In the device of the present invention, the first electrode acts as a first electrode of a nanogenerator and an anode of a metal pneumatic electricity. The first electrode may be one metal selected from the group consisting of Fe, Zn, Al, Ni, and Mg, or an alloy of two or more metals.

In the device of the present invention, the second electrode is a carbon structure layer formed on a porous hydrophilic polymer substrate, and the absorber of sunlight and a nanogenerator generating current on the surface of the carbon structure by the flow of droplets It acts as the second electrode of and the anode of the metal air battery. In the device of the present invention, the porous hydrophilic polymer substrate not only serves as a support for the carbon structure, but also serves to continuously provide moisture through capillary action. In the following examples, only paper is illustrated as a hydrophilic polymer material, but any material is irrelevant as long as water can be moved through a porous structure. That is, the hydrophilic polymer may be a natural polymer or a synthetic polymer, and is selected from the group consisting of paper or cotton, cellulose-based resin, polyacrylonitrile, polyvinyl alcohol, polyamide, polyethersulfone, polyethylene glycol, and hydrophilic polyurethane. It may consist of more than one, but is not limited thereto. In order to further increase the conductivity, the polymer may be crosslinked with a polymer electrolyte including an ionic liquid polymer.

It is preferable that the thickness of the porous hydrophilic polymer substrate is 1 µm to 5 ㎜. If the thickness of the substrate is too thin, stability as a support may be insufficient and the amount of moisture supplied may be limited, and if the thickness of the substrate is too thick, heat loss may occur. The optimum thickness may be set in consideration of the porosity, the size of the pores, and the interval between the pores depending on the material, which will be easy for those skilled in the art. The size of the pores, the spacing between the pores, and the porosity may also be easily set optimal conditions according to the material and detailed structure.

The apparatus of the present invention generates electricity by oxidizing the metal at the first electrode and reducing oxygen in the air at the second electrode by operating a metal air cell with a metal as a first electrode and a carbon structure layer as a second electrode. . In addition, the heat generated by the operation of the metal-air battery evaporates water from the carbon structure layer to produce water vapor, thereby controlling the surface temperature of the carbon structure layer to prevent overheating. In addition, since the carbon structure formed on the hydrophilic polymer substrate exhibits a high absorbance for light of a wide range of wavelengths and has high photothermal conversion efficiency, water supplied by the irradiated light can be efficiently evaporated to produce water vapor. Since the flow of water on the surface of the carbon structure generates electricity as known in the prior art, the flow of water on the surface of the carbon structure caused by evaporation of water vapor also generates electricity in the apparatus of the present invention. By such an interaction, it is possible to simultaneously produce water vapor and electricity in one device without merging a device for the flow of water and a separate device for generating electricity.

As the carbon structure, carbon black, fullerene, and carbon nano, which can induce a reduction reaction by increasing photothermal conversion efficiency when irradiating light, introducing an electrolyte by the flow of water, and inducing a reduction reaction using oxygen as an active material. At least one selected from the group consisting of tubes, graphene, carbon dots, carbon fibers, and conductive carbon may be used. In the following examples, only carbon nanotubes are illustrated, but other carbon structures can also induce electricity by introducing an electrolyte by the flow of water, and can act as a positive electrode of a metal air battery, so that the apparatus for simultaneous production of water vapor and electricity is used. It is natural that it can be applied.

It is preferable that the thickness of the carbon structure layer is 10 to 100 μm. As the thickness of the carbon structure layer increases, the photothermal conversion efficiency increases, thereby increasing the water vapor generation rate, and the increase in the water vapor generation rate, the supply of electrolyte is promoted. Therefore, if the thickness of the carbon structure layer is too thin, it is preferable that the thickness is 10 μm or more because the efficiency of producing water vapor and electricity decreases. On the other hand, as the thickness of the carbon structure layer increases, the porosity decreases, and when the thickness is 100 µm or more, it is difficult to form a uniform carbon structure layer. However, even if it is thicker than 100 μm, it is not excluded if it is possible to form a uniform layer having porosity.

Forming the carbon structure layer on the substrate is, for example, drop coating, screen printing, coating with a doctor blade, spraying with a spray, vacuum deposition as in the embodiment, or Various methods such as immersion coating in the dispersion may be used, and any method may be used as long as the carbon structure layer can be uniformly formed on the substrate.

In the vacuum deposition method used in the following examples, the carbon structure layer is formed only on one side of the substrate, but the carbon structure layer may be formed on both sides of the substrate by, for example, dip coating or vacuum deposition on both sides.

The device of the present invention is structurally in the form of a cone, pyramid, truncated cone or truncated cone. The cone may be a square cone, and includes a rain cone. Pyramids also include right and oblique pyramids. In the following, for convenience of explanation, the device of the present invention is described by exemplifying a conical structure.

Due to the three-dimensional conical structure, the apparatus of the present invention has a large surface area compared to a simple absorber in a flat shape, and can absorb a large amount of light regardless of direction, so that the water vapor production efficiency is high.

In addition, in the device of the present invention, since the temperature of the top during light irradiation is higher than that of the bottom (the side where the radius of the circle is the horizontal cross section of the cone is wider), the evaporation rate of water is high near the apex than the bottom. It causes a flow of water from the bottom to the apex, which promotes the introduction of the electrolyte into the pores between the two electrodes, allowing more electricity to be generated. In the apparatus of the present invention, the more water moves, the more efficient electricity production, so when connecting the second electrode to the electric wire, it is more preferable to connect the second electrode to the apex side in the case of a cone or pyramid, and to the side with a small cross-sectional area in the case of a truncated cone or pyramid.

The apex angle of the cone also affects the efficiency of water vapor and electricity production. If the apex angle is too large or too small, the effect due to the conical structure decreases, which reduces the efficiency of water vapor and electricity production. Therefore, it is preferable that the apex angle of the cone is 10 to 170°.

The cone has the additional advantage of stably floating in water due to the air filled in the lower space. The truncated cone is a cut in the apex of the cone, and while the evaporation area of water vapor is reduced compared to the cone, the evaporation of water vapor may occur on both sides of the substrate, so that water vapor and electricity can be effectively simultaneously produced. A straight pyramid whose base is not a circle but a polygon, but a straight truncated cone can simultaneously produce water vapor and electricity by the same principle.

The device of the present invention operates as a metal air cell to generate electricity, and at the same time, water that has moved through the porous structure of the substrate, the carbon structure layer and the hydrophilic polymer layer acts as an electrolyte by evaporation of water that is absorbed by floating in the water. Electricity is generated due to the potential difference between the carbon structure electrode and the metal wire, and because of the characteristic of the above-described conical structure, it is possible to produce water vapor and electricity even in dark conditions, so it is possible to generate electricity regardless of whether or not light is irradiated. Since the evaporation of water vapor is more active under light irradiation conditions than in dark conditions, and the movement of water on the surface of the carbon structure will increase accordingly, in the device of the present invention, the nanogenerator for electricity production under light irradiation conditions compared to dark conditions It is expected that the contribution will increase.

At this time, the device of the present invention is more excellent in electricity production capacity when the electrolyte is dissolved in the floating water. The type of electrolyte also affects the electrical output of the device according to the present invention. As the size of anions increases, the output is excellent. Cations showed high output in the order of K ⁺ >Ca ²⁺ >Na ⁺ when irradiated with light, and Ca ²⁺ >K ⁺ >Na ^{+ in the} dark condition. It will be easy to set the optimum concentration according to the type of electrolyte. When 0.6M NaBr was used as an electrolyte in the metal-air battery according to the following example, the output at 1 sun light intensity was 505.69 mW/m2, which was higher than that of any hybrid system of the prior art.

In order to further improve the output or voltage of the device of the present invention, it is natural that a plurality of devices can be electrically connected and used by serial connection or parallel connection, like a normal battery. As a result of observing the open-circuit voltage for 55,000 seconds (~15.3 hours) in the example in which four devices were connected by series connection, it was confirmed that a stable voltage can be supplied.

As described above, according to the apparatus for simultaneous production of water vapor and electricity of the present invention, while operating as a metal air battery, the hydrophilic porous structure of cellulose and carbon nanotubes provides an ideal channel for the flow of water, and the upper part of the conical structure Since the water vapor generation rate is high in the conical structure, the flow of water from the bottom to the top of the conical structure is induced, so there is no need to consume additional energy to induce the flow of water, and it is also operated as a nanogenerator, so that water vapor is not combined with a separate device. And electricity can be simultaneously produced with excellent efficiency.

In addition, the device for simultaneous production of water vapor and electricity of the present invention can produce water vapor and electricity even in dark conditions as the energy lost as heat in the conventional metal ion battery contributes to the production of water vapor, so it can operate without distinction between night and day, and produces water vapor. Because of this, the temperature of the electrode surface can be maintained at a constant temperature, so that it can be used more safely.

In addition, since the device for simultaneous production of steam and electricity of the present invention has a simple structure without a complicated device, it can be economically mass-produced, its size is free, it is stable against a wide range of light, does not use toxic substances, and is biodegradable. It is excellent and can be used as an eco-friendly alternative energy production means.

1 is a photograph of an apparatus for simultaneous production of water vapor and electricity in a cellulose structure and a conical structure on which carbon nanotubes are deposited, manufactured according to an embodiment of the present invention.
2 is a SEM, TEM image and XPS, Raman and UV spectra showing physical and chemical properties of a cellulose structure on which carbon nanotubes are deposited according to an embodiment of the present invention.
3 is a photograph and an infrared photograph of an experiment for evaluating water vapor production efficiency of a device for simultaneous production of water vapor and electricity according to an embodiment of the present invention.
4 is a photograph of a cellulose structure manufactured according to the thickness of a carbon nanotube layer in an embodiment of the present invention.
5 is a photograph and graph showing the water vapor production efficiency of a device for simultaneous production of water vapor and electricity according to the thickness of a carbon nanotube layer.
6 is a graph showing the steam production efficiency according to the apex angle of the conical structure of the device for simultaneous production of steam and electricity.
7 is an experimental photograph and result graph for evaluating the electricity production efficiency of the device for simultaneous production of steam and electricity according to an embodiment of the present invention.
8 is a photograph and graph showing the three-dimensional structural efficacy of the device for simultaneous production of water vapor and electricity of the present invention.
9 is a graph showing the electricity production efficiency of a device for simultaneous production of water vapor and electricity in various electrolyte solutions.
10 is a graph and experimental photographs showing electricity production efficiency of a device for simultaneous production of steam and electricity connected in series and in parallel.

Hereinafter, the present invention will be described in more detail with reference to the accompanying examples. However, these embodiments are only examples for easily explaining the content and scope of the technical idea of the present invention, thereby not limiting or changing the technical scope of the present invention. It will be obvious to those skilled in the art that various modifications and changes are possible within the scope of the technical idea of the present invention based on these examples.

[Example]

Example 1: Preparation of conical device for simultaneous production of steam and electricity

Multi-walled carbon nanotubes (MWCNTs, Hanwha Nanotech) were heat-treated at 300° C. in air for 60 minutes. Thereafter, the mixture was mixed with 37% hydrochloric acid and subjected to ultrasonic treatment for 1 hour, followed by filtration until the pH of the filtrate became neutral and washing with distilled water was repeated 5 times. Then, it was dried and purified in an oven at 70° C. for 24 hours.

Using a solution in which 20 mg of purified MWCNT was suspended in 200 ml DI water, MWCNT was coated on a cellulose filter paper by vacuum assisted deposition, and dried at 70° C. for 24 hours.

The MWCNT-coated cellulose was used to make a conical structure so that the apex angle of the cone from the 2/3 circle was 60° and the bottom diameter was 18 mm, and the interface was bonded using epoxy resin. The electrode was connected to the apex of the cone through a wire and suspended in water, and the wire to be used as the first electrode was cellulose to limit movement to prevent contact with the carbon structure layer, the second electrode, when immersed in water. It was fixed on filter paper. Accordingly, the first electrode is in contact with water, but is insulated from the carbon structure layer.

1a) and b) are photographs of cellulose coated with MWCNT and an apparatus for simultaneous production of conical steam and electricity using the same.

Example 2: Analysis of structural properties of a cellulose structure coated with carbon nanotubes

The morphology and thickness of carbon nanotubes adsorbed on cellulose filter paper were measured with a high-resolution scanning electron microscope (HRSEM; Hitachi S-4800, Hitachi) and a transmission electron microscope (TEM; JEM-2100F HR, JEOL). The structure was observed under 10 ^-10 Torr with a Multilab 2000 spectrometer equipped with monochromatic Al Kα (1486.65 eV) X-ray radiation. The binding energy scale was corrected by the binding energy position of Au 4f _7/2 core level at 83.98 eV. Raman spectra were recorded with a 532 nm DPSS laser.

FIG. 2 is a view showing the result, and the SEM image of a) shows that a MWCNT film having a thickness of 72 μm is obtained on a cellulose fiber film. b) shows the surface image of MWCNT, suggesting that the porous structure is formed by all of the MWCNT cellulose papers, which can act as an ideal channel for supplying water. The X-ray photoelectron (XPS) spectrum of c) shows that O-C=O, C=O, and C-O bonds exist on the MWCNT surface, which could also be confirmed by FTIR (Thermo Scientific) (data not shown). Guo et al. reported that charge rearrangement was caused by the adsorption of water on graphene flakes having different functional groups through calculation using density function theory (DFT). According to the calculation results, a charge double layer is formed at the interface between water and graphene, and when three layers of water are covered in the C-O-C group, about 0.7e is consumed, and when the C-O-C group is removed, it drops to 0.003e. Therefore, the functional groups of MWCNT as described above are essential for the generation of electricity.

MWCNT is composed of loosely stacked disordered graphene flakes can be confirmed in the TEM image of d), which can also be confirmed in the Raman spectrum of e). As a result of measuring the contact angle of the structure prepared in Example 1, it was confirmed that the MWCNT thin film exhibits hydrophilicity, which means that water can move by capillary phenomenon along the porous structure of the MWCNT in addition to the cellulose support.

According to the prior art, the interaction of water and MWCNT, in particular the flow of water induced by evaporation of water inside the porous MWCNT film, is considered the main reason for generating electricity. Therefore, when a conical structure is manufactured using the structure manufactured according to the above embodiment, water flows to the top of the structure due to capillary phenomenon as water is evaporated by sunlight or self-evaporation. Because electricity can be generated by inducing power, it is expected that water vapor and electricity can be generated at the same time without using a separate device.

FIG. 2F shows the results of measuring the refraction and transmission properties of the absorber using a UV-Vis-NIR spectrometer (Solidspec-3700, Shimadzu) in order to evaluate the solar absorption efficiency. In the above drawing, it can be seen that the structure has a transmittance of 250 to 800 nm, and light of a wide wavelength is blocked by the MWCNT.

Example 3: Evaluation of steam production capability in laboratory of a device for simultaneous production of steam and electricity

1) Water vapor production capability evaluation device

In order to calculate the light-to-heat conversion efficiency of the device for simultaneous production of water vapor and electricity prepared in Example 1, a device for evaluating the water vapor production capacity by 1 sun irradiation with real-time weight change was designed.

To measure the water evaporation rate of the device for simultaneous steam and electricity production, place a 50 mL container coated with polystyrene foam on a scale connected to a computer, and simulate sunlight (350~1800 ㎚, solar simulator, Hal 320 W, ASAHI) on the top. ) Was placed. Put a polystyrene foam (EPS) plate expanded to a size of 2×2 cm in a cup coated with polystyrene foam on the inner wall, place 2×4 cm white cellulose paper in the center of the EPS plate, fold both ends inward, and then put it in water. It was made to be locked. The device of the conical structure was placed on a piece of paper, and water was put in the cup so that both ends of the paper were submerged in water while the water level was below the EPS plate. In order to minimize evaporation of water in the gap between the device and the container, the upper surface of the container was covered with polystyrene foam. The height above the water surface of the conical device was 16 mm, and the distance from the top of the cone to the water-air interface was 8 mm. When the device was completely wet, the simulated sunlight was turned on and the weight was measured every 10 seconds to calculate the evaporation amount. The temperature change during the evaporation process was measured using a thermal imaging camera (SEEK) and a K thermocouple temperature probe (Testo735).

3A is a representative optical image of an experimental apparatus for evaluating water vapor production capacity, and b) and c) are representative infrared images of a cone-structure apparatus when irradiated with light of 1 sun light intensity for 30 minutes. During the experiment, the ambient temperature was 22℃ and the relative humidity was 40%, and the surface temperature of the device during self-evaporation was similar to the ambient temperature. However, at the time of irradiation with a light intensity of 1 sun, the temperature of the device increased to 34°C after 30 minutes of light irradiation, and the temperature at the top of the conical structure was the highest and decreased as it went down. Therefore, the evaporation rate of water increases as it goes up the conical structure, and the movement of water from the bottom of the absorber to the top is promoted.

2) Evaluation of water vapor production capacity according to the thickness of the CNT layer

Using the device designed in 1), the effect of the thickness of the CNT layer on the steam production was evaluated. To this end, 100 mg of MWCNT purified in Example 1 was suspended in 1000 ml DI water, and then MWCNT was coated on cellulose filter paper by vacuum assisted deposition using 50, 100, 200 or 300 ml of each solution, and 70° C. After drying for 24 hours, a conical device for simultaneous production of steam and electricity was manufactured by the same method as in Example 1.

4 is a photograph of a structure on which MWCNT was deposited by the above method. When a 300 ml solution was used, a uniform MWCNT layer was not formed. Thus, using a conical structure prepared by using 50, 100 and 200 ml of solutions, respectively, the water vapor production capacity was evaluated by the same method as in 1), and the results are shown in FIG. 5.

5A) to 5D are SEM images of cellulose and cellulose on which MWCNT is deposited. As the amount of the MWCNT solution increases, the thickness of the MWCNT layer gradually increases to 31, 50 and 72 µm, whereas the porosity decreases. Show. e) shows the solar spectrum and the absorbance of each sample. The absorbance of the cellulose on which the MWCNT layer of 31, 50 and 72 µm is formed is 98.1, 98.5 and 98.4%, respectively, showing excellent absorbance for a wide range of wavelengths at all thicknesses. Done. f) is the measurement of the temperature of the top of the conical structure when irradiating the conical structure with 1 sun light in the absence of water. It shows that the temperature rises to the equilibrium temperature of 45-50℃ within 3 minutes. . When the device for simultaneous production of water vapor and electricity was floated on water, the maximum temperature decreased somewhat as shown in g), because in the absence of water, the absorbed energy is released as heat, but in the presence of water, it is used to generate water vapor. It is considered to be. In the device floating in water, it took about 200 to 300 seconds to equilibrate the temperature. Zhao et al. (Nat. Nanotech., 2018, doi: 10.1038/s41565-018-0097-z) reported different correlations between surface temperature and time in different types of energy consumption. Therefore, it is interpreted that most of the energy was used to increase the temperature in the early period of rapid temperature rise, and the energy was mainly used for evaporation in the later equilibrium period. h) confirms the inflection point of the temperature-time graph, and shows that there is an energy balance between heating and evaporation of water. As the thickness of the MWCNT layer increases, the inflection temperature also decreases, so it can be predicted that the evaporation efficiency of water will increase. i) and j) are graphs showing the amount and rate of water vapor generation, and show that the amount of water vapor or evaporation rate increases as the thickness of the MWCNT layer increases. As the thickness of the MWCNT layer increased from 0 to 72㎛, the evaporation rate increased from 0.439 to 1.651 kg/m².h when irradiated with 1 sun light.

In addition, FIG. 4 shows that water vapor evaporates not only during light irradiation but also under dark conditions, which means that water vapor can be generated both day and night by operating as a metal air battery.

3) Water vapor production capability evaluation according to the apex angle of a device for simultaneous production of water vapor and electricity

Conical metal-air batteries with apex angles of 45, 60, and 90° using cellulose on which MWCNTs prepared in Example 1 were deposited in order to confirm the effect of the conical structure of the device for simultaneous production of water vapor and electricity on the production of water vapor Was prepared.

6A shows the temperature change when the device for simultaneous production of water vapor and electricity is irradiated with 1 sun light, and the internal drawing shows the temperature change (left) and the inflection point (right) in the absence of water. ) Is shown. According to a), when the apex angle is 60°, the inflection temperature is the lowest and the water vapor production rate is expected to be the highest. From the actual measurement results b) and c), it can also be confirmed that the conical structure device with a vertex angle of 60° has the highest water vapor production capacity, and the dark conditions in the conical structure device with a vertex angle of 60° and 1 sun light intensity The evaporation rates were 0.618 and 1.651 kg/m 2 .h, respectively.

In Fig. 6d), the evaporation rate according to the thickness of the MWCNT layer and the apex angle of the cone structure during light irradiation is summarized and shown. The internal figure shows the evaporation rate during self-evaporation.

Example 4: Evaluation of in-laboratory electricity production capability of a device for simultaneous production of steam and electricity

1) Electricity production capability evaluation

In order to evaluate the electricity production ability of the conical structure prepared in Example 1, the conical structure device prepared in Example 1 was floated in a Petri dish containing DI water. After connecting the electrodes to the wires mounted on the bottom and top, the current and voltage signals were collected and recorded on a potentiometer (IVIUMSTAT) through the J-t curve (interval: 10 seconds) and V-t curve (interval: 10 seconds), respectively.

7A is a schematic diagram of this experiment, and b) is a photograph of the actual experiment. 7C is an output curve calculated from the I-V curve and the I-V curve under the dark conditions measured by the experiment of b) and irradiation with 1 sun light intensity. When irradiated with 1 sun light, as both the open-circuit voltage and short-circuit current increased compared to the dark condition, the output of the device of Example 1 at 1 sun light intensity was 13.18 mW/m2, which is 8.24 mW/m2 in dark conditions. Compared to that, it increased about 1.6 times.

The output in dark conditions contributes to the production of electricity by the operation of the air ion battery, as well as the electricity generation of the nanogenerator by the movement of water due to the heat generated during the operation of the air ion battery and water vapor generated by natural drying. Is interpreted as. In the light irradiation condition, as the movement of water due to water vapor generation increases, the output of the nanogenerator increases, so it can be seen that the total output increases in the light irradiation condition compared to the dark condition.

2) Efficacy evaluation by structure in a device for simultaneous production of steam and electricity

Using a cone structure and a rectangular device, the effect of the cone structure on electricity production capacity was additionally confirmed.

To this end, MWCNTs were vacuum-deposited on cellulose by the same method as in Example 1, and rectangular and triangular structures were fabricated with the same height and bottom diameter of a cone using this. The electrodes were connected to the upper and lower portions of the rectangular and triangular metal-air batteries through wires, respectively. As in Example 1, the wire connected to the lower part was first coated with an epoxy resin on the MWCNT so that the wire was in contact with water but not directly in contact with the MWCNT.

Using the rectangular device and the triangular device manufactured by the above method, electricity production capacity was evaluated in dark conditions. 8 is a photograph showing an actual experiment and a graph showing voltage over time as a result.

In FIG. 8, it can be seen that the triangular device produces electricity with a voltage that is about twice as high as that of the rectangular device, although the total area is only 1/2 of that of the rectangular device. This means that in the apparatus for simultaneous production of steam and electricity of the present invention, three-dimensional structures such as cones, truncated cones, pyramids, and pyramids play an important role.

3) Evaluation of electricity production capacity using electrolyte solution

Since water has a very low ion concentration, it was confirmed that the ions could improve the output of the device for simultaneous production of water vapor and electricity by using an electrolyte solution. The experiment was carried out in the same manner as in 1), except that an electrolyte solution was used instead of water.

9 is a graph showing the output of the device in various electrolytes. a) shows the output according to the concentration of NaCl. As the concentration of NaCl increases to 0.6 M, the output also increases, but when the concentration of NaCl further increases, the output decreases. This is thought to be because NaCl is precipitated as water evaporates from the top of the conical structure when the concentration of NaCl is too high. The output at 0.6 M NaCl is 107.79 mW/m2, which is more than eight times higher than that of water.

As it was confirmed that the electrolyte was advantageous in improving the output, the effect of the type of positive or negative ions on the output was identified. At this time, the concentration of the electrolyte was fixed to 0.6 M. 9B shows the effect of negative ions and c) shows the effect of positive ions. As the size of the negative ions increases, the output improves, and when 0.6M NaBr is used, the output increases to 255.67 mW/m2. Cations did not show a tendency according to the size, and when 0.6M KCl was used, the output was 505.69 mW/m2, which was higher than that of the conventional hybrid system. More remarkably, the output in dark conditions also increased significantly depending on the cations, resulting in a value of 252.4 mW/㎡ when 0.6M KCl was used and 266.2 mW/㎡ when 0.6M CaCl ₂ was used.

Pond water and seawater are known to contain various ions. Accordingly, the output was measured using water collected from a pond at Chungnam National University and seawater. d) shows the results, which also showed higher output than water.

4) Evaluation of electricity production capability by serial connection and parallel connection

It is expected that the output of the device for simultaneous production of steam and electricity can be amplified through serial connection and parallel connection, and this was confirmed through Examples.

After manufacturing 4 devices of the same conical structure by the method described in Example 1, IV curves in dark conditions for a device in which each device and 4 devices are connected in series and a device that is connected 4 devices in parallel And an output curve calculated from the IV curve was obtained. 10A and 10B are graphs showing the results. First, it can be seen that each of the four devices has excellent reproducibility with an open-circuit voltage of 0.65 V and a short-circuit current of 27 ㎂. The open circuit voltage of the device was amplified to 2.3V by serial connection, and the short circuit current increased to 120 ㎂ by parallel connection. c) is a graph showing a photograph of a series-connected device and an open-circuit voltage as a function of time, showing that a constant open-circuit voltage of 2.3 V is maintained for 55,000 seconds, so that the device of the present invention produces substantial water vapor and electricity simultaneously for long-term electricity production. It shows that it can be used as a dragon device.

Claims (9)

The metal electrode as the first electrode,
A carbon structure layer deposited on a porous hydrophilic polymer substrate having a hollow cone, pyramidal cone, truncated cone or pyramidal structure as a second electrode,
An apparatus for simultaneous production of water vapor and electricity, characterized in that the first electrode is used in a suspended state by contacting the bottom surface of the hydrophilic polymer substrate with water immersed in the first electrode.
The method of claim 1,
The first electrode is a device for simultaneous production of water vapor and electricity, characterized in that one metal selected from the group consisting of Fe, Zn, Al, Ni, and Mg or an alloy of two or more metals.
The method of claim 1,
The hydrophilic polymer is water vapor and electricity, characterized in that it is made of at least one selected from the group consisting of paper, cotton, cellulose resin, polyacrylonitrile, polyvinyl alcohol, polyamide, polyethersulfone, polyethylene glycol, and hydrophilic polyurethane. Devices for simultaneous production.
The method of claim 1,
The carbon structure is an apparatus for simultaneous production of water vapor and electricity, characterized in that at least one selected from the group consisting of carbon black, fullerene, carbon nanotube, graphene, carbon dot, carbon fiber and conductive carbon.
The method according to any one of claims 1 to 4,
The carbon structure layer is a device for simultaneous production of water vapor and electricity, characterized in that the thickness of 10 ~ 100 ㎛.
The method according to any one of claims 1 to 4,
The device for simultaneous production of water vapor and electricity, characterized in that the apex angle of the cone, pyramid, truncated cone, or truncated cone is 10 to 170°.
The method according to any one of claims 1 to 4,
The apparatus for simultaneous production of steam and electricity is an apparatus for simultaneous production of steam and electricity, characterized in that it generates electricity irrespective of whether or not irradiated with light.
The method according to any one of claims 1 to 4,
An apparatus for simultaneous production of steam and electricity, characterized in that an electrolyte is dissolved in the water.
An apparatus for simultaneous production of steam and electricity, characterized in that the device for simultaneous production of steam and electricity according to any one of claims 1 to 4 is connected in series or in parallel.

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