Preparation method of film type photo-active material treated with a metal chloride

Film type photoactive material treated with metal chloride and its manufacturing method {Preparation method of film type photo-active material treated with a metal chloride}

1 is CdS/TiCl₄Film, CdS/TiO₂/TiCl₄It is a graph comparing catalytic performance when each of the film and the CdS film is used as a catalyst for photolysis of water.

<background-art><p>The present invention relates to a film-type photoactive material surface-treated with a metal chloride and a method for manufacturing the same, and more particularly, to a metal sulfide such as CdS and ZnS, TiO₂, WO₃ By treating and modifying the surface of a film prepared using a metal oxide such as a metal oxide such as a metal oxide or a mixture thereof with a metal chloride, it is possible to connect and densify the particles constituting the film, thereby preventing recombination of electrons and holes generated by light absorption. high-efficiency film-type photoactive material that can be used as a photocatalyst to greatly improve reaction activity and improve light conversion efficiency when used as a light absorption window of a solar cell; It relates to a manufacturing method thereof.</p><p>Metal sulfides, metal oxides, or mixtures thereof are applied as photocatalyst materials used in wastewater treatment processes or in hydrogen production processes by photolysis of water. Among the photocatalyst materials described above, CdS, ZnS, TiO₂ It is used alone or in combination because it has excellent light absorption and photoexcitation properties, and if necessary, a transition metal type third auxiliary component, for example, Pt, Rh, Ni, etc. is added thereto and used.</p><p>Until now, photoactive materials have been mainly manufactured and used in the form of particles, but recently, studies to use them as solar cells by manufacturing in the form of a film are being actively conducted. is increasingly increasing.</p><p>On the other hand, in the conventional photocatalyst field, a slurry-type photoactive material that is relatively easy to manufacture and has a relatively high light efficiency has been mainly applied. In the case of a reaction using a slurry-type photoactive material as a photocatalyst, it is difficult to recover and reuse the reaction catalyst because it is operated in the form of a slurry by dispersing the powder-type photocatalyst in a waste liquid or a water electrolyte system, and the reaction system is also a batch type. Therefore, a water treatment system using a slurry-type photoactive material has limitations in being applied as a mass production system, and also has a decisive drawback in that it cannot directly use sunlight instead of an artificial light source as a main light source.</p><p>In principle, the film-type photoactive material overcomes various disadvantages of the slurry-type photoactive material. Although it is known that the film has poor stability and durability, as well as when applied to a solar cell , the photoactive material is fixed to the light absorption window and the light conversion efficiency is low, so it is not widely used in reality. CdS/CdTe based, dye/TiO₂ A film-type photoactive material made of a system or the like can be used as a light absorption window of a solar cell, but here too, the stability of the film and improvement of optical properties remain a major problem.</p></background-art><tech><p>Accordingly, the present inventors have studied for a long time a method for simultaneously solving the problems of stability and high efficiency while taking advantage of the advantages of the film-type photoactive material. As a result, when the surface of a film-like semiconductor material prepared using a metal sulfide, a metal oxide, or a mixture thereof as a material is modified by heat treatment with a metal chloride solution such as titanium tetrachloride, the surface of the particles such as CdS becomes fine by the metal chloride solution. It is etched to increase the density of the film, and the metal oxide generated from the metal chloride coats the particle surface such as CdS to increase the stability of the film and the connection between each particle, thereby increasing the overall optical efficiency and securing the stability of the film. As a result, the present invention was completed.</p><p>Accordingly, an object of the present invention is to provide a novel film-type photoactive material prepared by surface-treating a film made of a metal sulfide, a metal oxide, or a mixture thereof with a metal chloride, and a use for applying the same to a photocatalyst or a solar cell.</p></tech>

<p>The present invention provides a film-type photoactive material surface-treated with a metal chloride in which a metal sulfide, a metal oxide, or a mixture thereof is contained as an essential component, and the surface of a film prepared by containing a transition metal component as necessary is coated with a metal chloride. is characterized by</p><p>In addition, the present invention is a method for producing a film-type photoactive material by containing a metal sulfide, a metal oxide, or a mixture thereof as an essential component and, if necessary, a transition metal component as an auxiliary component, the surface of the film-type photoactive material It includes a method for producing a film-type photoactive material surface-treated with a metal chloride prepared by surface heat treatment at a temperature of 350 to 550 ° C. with an aqueous metal chloride solution.</p><p>In addition, the present invention includes a method of using the photoactive material surface-treated with the metal chloride prepared by the above method as a photolysis catalyst.</p><p>In addition, the present invention includes a solar cell manufactured using the photoactive material surface-treated with a metal chloride by the above manufacturing method.</p><p>The present invention will be described in more detail as follows.</p><p>The present invention is used as a light absorption window of a photocatalyst or solar cell by heat-treating the surface of a film prepared by hydrothermal treatment of metal sulfide, metal oxide, or a mixture thereof, and a transition metal component with metal chloride to increase light efficiency and improve film stability. It relates to a novel photoactive material to be promoted, a method for manufacturing the same, and a use thereof.</p><p>The method of manufacturing the photoactive material according to the present invention will be described in more detail for each process as follows.</p><p>First, one or a mixture of two or more selected from a metal sulfide and a metal oxide may be prepared as a sol at room temperature, and, if necessary, a transition metal component may be mixed thereto as a third auxiliary component. The raw material mixture is hydrothermally treated at a temperature of 160 to 240° C. to obtain a crystalline phase while controlling the particle size in the range of 10 to 20 nm. The metal sulfide, metal oxide, or transition metal component as a third auxiliary component used in the present invention is a material known in the art. When these raw materials are specifically exemplified, CdS, ZnS, etc. are selectively used as the metal sulfide, and TiO is used as the metal oxide.₂, WO₃ Select and use Pt, Rh, Ni, etc. as transition metal components.</p><p>Then, the hydrothermal-treated raw material mixture is concentrated to have a solid content of 10 to 30% by weight, preferably 15 to 20%, and polyethylene glycol is added as a binder to the concentrated raw material mixture, and a conventional coating method For example, a film having a thickness of 1 to 20 µm, preferably 4 to 12 µm, is produced by using a casting method or a spin coating method. At this time, polyethylene glycol is added in an amount of 10 to 70 wt%, preferably 20 to 40 wt%, based on the solid content of the raw material mixture.</p><p>Then, in order to remove the polyethylene glycol added as a binder from the film, heat treatment is carried out at a temperature of 350 to 550 °C, preferably 400 to 450 °C, and then the surface of the film is treated with an aqueous metal chloride solution. The metal chloride used characteristically in the present invention is TiCl₄, VCl₄, SnCl₄ and the like, particularly preferably 0.01 to 0.8 M, preferably 0.1 to 0.8 M, using deionized water to prepare a liquid metal chloride at room temperature. Prepare and use at a concentration of 0.5 M. In addition, if the surface treatment amount of the metal chloride is low below the above range, the effect desired by the present invention cannot be obtained. The metal chloride selected and used as a surface treatment material in the present invention has strong acidity in aqueous solution and becomes a metal oxide over time. Thus, the density of the film is increased, and the stability of the film and the connection between each particle are increased, thereby increasing the overall light efficiency and securing the stability of the film.</p><p>Then, after washing the film using deionized water, heat treatment at a temperature of 350 to 550 °C, preferably 400 to 450 °C, to prepare a film-type photoactive material for the purpose of the present invention. </p><p>The film-type photoactive material manufactured by the manufacturing method as described above can be directly used as an absorption window of a solar cell, or the surface of the photoactive material film is platinum-coated by sputtering, chemical, electrical methods, etc. to obtain water or H₂It can also be applied as a photocatalyst for photolysis of S and the like.</p><p>The present invention will be described in more detail based on the following examples, but the present invention is not limited thereto.</p><p><b><u>Example 1</u></b></p><p>A 0.5 M aqueous solution of cadmium nitrate (500 mL) and a 0.5 M aqueous sodium sulfide solution (500 mL) were mixed at room temperature with stirring to prepare a CdS sol having a size of 3 to 4 nm. After hydrothermal treatment of the CdS sol at 240° C., the CdS sol was concentrated to a solid content of 20% by weight. Polyethylene glycol corresponding to 30% by weight was added based on the solid content of the concentrated CdS sol, and a film having a width and length of 7.5 cm and a thickness of 8 μm was prepared by a casting method, and then heat-treated at 450°C.</p><p>The prepared CdS film was mixed with 0.1 M TiCl₄ An aqueous solution was supplied and the surface was treated for 60 minutes. At this time TiCl₄The thickness of the film decreased due to the etching effect of After washing the surface-coated photoactive material film with deionized water, heat treatment at 450 °C for 60 min. CdS/TiCl₄ A film was prepared.</p><p><b><u>Example 2</u></b></p><p>A CdS sol having a size of 3 to 4 nm was prepared by mixing a 0.5 M aqueous solution of cadmium nitrate (500 ml) and a 0.5 M aqueous sodium sulfide solution (500 ml) at room temperature, and TiO composed of anatase-type particles.₂ The sol was added to correspond to 5% by weight based on the weight of the CdS sol and mixed. After hydrothermal treatment of the mixed sol at 240° C., it was concentrated to a solid content of 20 wt%. Polyethylene glycol corresponding to 30% by weight was added based on the solid content of the concentrated mixed sol, and a film having a width and length of 7.5 cm and a thickness of 8 μm was prepared by a cast method, and then heat-treated at 450°C.</p><p>Prepared CdS/TiO₂Films were mixed with 0.1 M TiCl₄ An aqueous solution was supplied and the surface was treated for 60 minutes. At this time TiCl₄The thickness of the film decreased due to the etching effect of After washing the surface-coated photoactive material film with deionized water, heat treatment at 450 °C for 60 min. CdS/TiO₂/TiCl₄ A film was prepared.</p><p><b><u>comparative example</u></b></p><p>A CdS sol having a size of 3 to 4 nm was prepared by mixing a 0.5 M aqueous solution of cadmium nitrate (500 ml) and a 0.5 M aqueous sodium sulfide solution (500 ml) at room temperature. After hydrothermal treatment of the CdS sol at 240° C., the CdS sol was concentrated to a solid content of 20% by weight. Polyethylene glycol corresponding to 30% by weight was added based on the solid content of the concentrated CdS sol, and the film was prepared by a cast method with a width and length of 7.5 cm and a thickness of 8 μm, and then heat-treated at 450° C. to prepare a CdS film.</p><p><b>Experimental Example 1: Use as a photocatalyst</b></p><p>Platinum was coated on the surface of the film-type active material prepared in Examples 1 to 2 and Comparative Examples by sputtering, and continuous flow type H₂O/H₂After being installed in the S photolysis reactor, light was irradiated with a xenon lamp, and the light intensity was 100 mW/cm 2 under standard sunlight AM 1.5 conditions to produce hydrogen.</p><p>Then, after irradiating light, the average hydrogen generation rate was measured and shown in Table 1 below.</p><p><tables id="1"><img file="KR100351633B1_D0001.tif" /></tables></p><p>In addition, CdS/TiCl prepared in Examples 1 to 2 and Comparative Examples₄, CdS/TiO₂/TiCl₄ and CdS film were shown in the accompanying drawings by comparing the performance of each used as a catalyst for photolysis of water.</p><p>According to FIG. 1, CdS/TiCl prepared by surface-treating the surface of the CdS film with titanium tetrachloride, which is a metal chloride.₄ In the case of the film, it can be seen that the stability of the film is also improved with the increase of the hydrogen generation rate. In addition, without using CdS alone, CdS/TiO₂ CdS/TiO prepared by preparing a film in a composite form and then surface-treating it with titanium tetrachloride₂/TiCl₄ In the case of the film, it can be seen that while maintaining a high hydrogen generation rate, the film stability is also very good. On the other hand, in the case of a CdS film prepared without surface treatment of the CdS film surface with titanium tetrachloride, which is a metal chloride, the hydrogen generation rate, which is a measure of catalyst performance, is very high. It can be seen that there is a problem that not only is insignificant, but also the lifespan is short.</p><p><b>Experimental Example 2: Use as a solar cell</b></p><p>A photoelectrochemical solar cell system was constructed by using the film-type photoactive material and the platinum electrode prepared in Examples 1 and 2 and Comparative Examples as main and auxiliary electrodes, respectively, and irradiating light with a xenon lamp, in which case the light intensity was standard. It was 100 mW/cm&lt;2&gt; which is sunlight AM 1.5 condition.</p><p>Then, the average photocurrent after irradiating light was measured and shown in Table 2 below.</p><p><tables id="2"><img file="KR100351633B1_D0002.tif" /></tables></p>

<p>As described above, the present invention relates to the film's compactness and properties by modifying the surface of a film prepared by using a metal sulfide, a metal oxide, or a mixture thereof prepared by hydrothermal treatment as a raw material, by surface heat treatment with a metal chloride solution. ensure stability It is useful as a light absorption window of a photocatalyst or solar cell because it increases the light efficiency of course.</p>