WO2023219397A1 - Hydrogen-doped reduced titania powder and preparation method therefor - Google Patents

Abstract

A preparation method for hydrogen-doped reduced titania (TiO2-x) powder of the present invention comprises: a mixture preparation step for mixing TiO2 particles, hydrides, and mixed salts; a crystallization step for preparing a crystallized product by reacting a mixture at a temperature higher than or equal to the eutectic melting point of the mixed salts; and a powder acquisition step for acquiring TiO2-x powder (in the formula, X is a rational number between 0.00001 and 2) from the crystallized product.

Description

Hydrogen-doped reduced titanium oxide powder and method for producing the same

The present invention relates to hydrogen-doped reduced titanium oxide powder (TiO _2-x ) and a method for producing the same. Specifically, it relates to hydrogen-doped reduced titanium oxide powder (TiO _2-x ) with high optical absorption of visible light and a method for producing the same.

A photocatalyst is a catalyst that is activated by light energy. Unlike general catalysts, photocatalysts are photoactive even at room temperature, have simple reaction equipment, and can be used on a small scale. In addition, harmful substances are oxidized and decomposed into harmless carbon dioxide (CO ₂ ) and water (H ₂ O), and the reaction can proceed in the wavelength range of ultraviolet rays and visible rays.

Materials that can be used as photocatalysts include titanium oxide (TiO ₂ ), zinc oxide (ZnO), cadmium sulfide (CdS), tungsten trioxide (WO ₃ ), tin oxide (SnO ₂ ), zirconium oxide (ZrO ₂ ), and iron oxide (Fe). ₂ O ₃ ), cerium oxide (CeO ₂ ), etc. ZnO, similar to TiO ₂ , has an excellent effect on the decomposition of TCE (trichloroethylene), but by absorbing light, the catalyst itself is decomposed by light. Additionally, there is a possibility of secondary contamination because it generates harmful Zn ions. CdS has a band gap (or forbidden band) energy (Eg) of 2.4 eV and can be excited by light in the visible range. However, it has a problem of poor durability because the catalyst structure is destroyed when exposed to light. WO ₃ has good photocatalytic efficiency only for certain materials, and for other materials, the photocatalytic efficiency is not as good as TiO ₂ , so its applicable range is very limited. On the other hand, TiO ₂ not only has good photocatalytic activity, but also has excellent durability and wear resistance, does not change its physical properties, is environmentally friendly, and has no concerns about secondary pollution even when disposed of. For this reason, TiO ₂ is the most widely used among various types of photocatalysts.

TiO ₂ can be broadly divided into anatase type and rutile type depending on its crystal structure. The band gap energy (Eg) of anatase-type TiO ₂ is 3.23 eV, and that of rutile-type TiO ₂ is 3.02 eV. When converted to wavelength, they are 388 nm and 413 nm, respectively. Therefore, TiO ₂ hardly reacts in the visible light range of 400 nm to 800 nm, but reacts in the ultraviolet light range of 270 nm to 400 nm. It is known that about 5% of sunlight reaching the earth's surface is ultraviolet rays, and about 40% is visible light. As commercialized TiO ₂ reacts with ultraviolet rays, catalyst efficiency can be relatively increased if it can react with visible rays, which account for 40% of sunlight.

Accordingly, there is a need to develop technology for TiO ₂ that has excellent activity and stability against not only ultraviolet rays but also visible rays.

Meanwhile, the above-mentioned background technology cannot necessarily be said to be known technology disclosed to the general public before the application for the present invention.

One embodiment of the present invention aims to provide a hydrogen-doped reduced titanium oxide powder (TiO _2-x ) having excellent light absorption for visible light and a method for manufacturing the same.

Additionally, an embodiment of the present invention aims to provide hydrogen-doped reduced titanium oxide powder (TiO _2-x ) having a stable phase and a method for producing the same.

Furthermore, an embodiment of the present invention aims to provide a hydrogen-doped reduced titanium oxide powder (TiO _2-x ) with relatively improved processability and a method for manufacturing the same.

As a technical means for achieving the above-described technical problem, the method for producing hydrogen-doped reduced titania (TiO _2-x ) powder of the present invention includes a mixture preparation step of mixing TiO ₂ particles, hydride, and mixed salt, mixture It includes a crystallization step of producing a crystallized product by reacting at a temperature above the eutectic melting point of the mixed salt, and a powder obtaining step of obtaining TiO _2-x powder (where X is a free number between 0.00001 and 2) from the crystallized product. do.

For example, the hydride is 1 selected from the group consisting of MgH ₂ , NaAlH ₄ , NaBH ₄ , LiAlH ₄ , CaH ₂ , ZrH ₂ , TiH ₂ , VH ₂ , NaH, LiH, KH, RbH, CsH and Mg ₂ FeH ₆ It can be characterized as having more than one species.

For example, the mixed salt may be two or more selected from the group consisting of LiCl, NaCl, KCl, RbCl, CsCl, Li ₂ SO ₄ , Na ₂ SO ₄ , K ₂ SO ₄ and K ₃ PO ₄ .

For example, the mixed salt may be characterized as having a eutectic melting point of less than 700°C.

For example, the mixture preparation step may include a first mixture preparation step of mixing TiO ₂ particles and hydride to prepare a first mixture, and a second mixture preparation step of preparing a second mixture by adding a mixed salt to the first mixture. You can.

For example, the first mixture preparation step may include mixing TiO ₂ particles and hydride at a molar ratio of 1:1 to 1:20.

For example, the second mixture preparation step may include mixing the first mixture and the mixed salt at a mass ratio of 1:5 to 1:120.

For example, the crystallization step may include a heat treatment step and a cooling step.

For example, the heat treatment step may include heat treatment at a temperature of 700°C or more for 3 hours or more.

For example, the powder obtaining step may include a washing step of washing the crystallized product, a filtration step of filtering the washed crystallized product, and a step of drying the filtered crystallized product.

For example, the method for producing reduced hydrogen-doped titania (TiO _2-x ) powder may further include a post-treatment step of heat treating the dried product.

For example, the post-treatment step may include heat treatment for 1 to 3 hours.

For example, hydrogen-doped reduced titania (TiO _2-x ) powder may have a particle diameter of 5 nm to 100 μm.

For example, hydrogen-doped reduced titania (TiO _2-x ) powder may have an optical absorption of 0.35 au or more in the visible light range (400 to 800 nm).

For example, hydrogen-doped reduced titania (TiO _2-x ) powder may have an XRD spectrum including (110), (101), and (211) diffraction peaks.

According to any one of the means for solving the problems of the present invention described above, the hydrogen-doped reduced titanium oxide powder (TiO _2-x ) according to an embodiment of the present invention has excellent light absorption not only for ultraviolet rays but also for visible rays. You can.

In addition, the hydrogen-doped reduced titanium oxide powder (TiO _2-x ) according to an embodiment of the present invention can exist stably without easily changing into another phase at a certain temperature or pressure.

The method for producing hydrogen-doped reduced titanium oxide powder (TiO _2-x ) according to an embodiment of the present invention can easily control the size and shape of the titanium oxide powder.

In addition, the method for producing hydrogen-doped reduced titanium oxide powder (TiO _2-x ) according to an embodiment of the present invention can be performed at a low process temperature and a short process time, thereby improving process ease.

The effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. will be.

Figure 1 is a flowchart of a method for producing hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to an embodiment of the present invention.

Figure 2a is a diagram showing hydrogen-doped reduced titanium oxide (TiO _2-x ) prepared in Example 1.

Figure 2b is a diagram showing hydrogen-doped reduced titanium oxide (TiO _2-x ) prepared in Example 6.

Figure 3 shows the results of XRD analysis of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to the present invention.

FIGS. 4A to 4D are SEM images of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to the present invention.

Figure 5 is a diagram showing specific areas where EDS analysis was performed on the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention.

FIGS. 6A to 6D are diagrams showing EDS analysis results for each region of FIG. 5.

Figure 7 is a diagram showing the results of SEM elemental mapping of the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention.

Figure 8 is a diagram showing the results of UV-Vis analysis of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention.

Below, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are given similar reference numerals throughout the specification.

Throughout the specification, when a part is said to be “connected” to another part, this includes not only cases where it is “directly connected,” but also cases where it is “indirectly connected” with another component in between. . Additionally, when a part "includes" a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

The method for producing hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to an embodiment of the present invention (where X is a rational number between 0.00001 and 2) reduces TiO ₂ through heat treatment. More specifically, the method for producing hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to an embodiment of the present invention reduces TiO ₂ through a molten salt method. The molten salt method refers to a method of growing crystals using salt with a low melting temperature.

Molten salt means salt in a molten state. Molten salt has excellent heat transfer properties, heat storage properties, and fluidity. Therefore, when salts are mixed and heat treated, the heating rate is faster than the heating rate in the air, and the cooling rate is also fast, enabling rapid processing. In particular, since mixed salts have a lower melting temperature than single salts, the heat treatment temperature can be lower than when using single salts.

Hereinafter, the present invention will be described in detail with reference to the attached drawings.

Figure 1 is a flowchart of a method for producing hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to an embodiment of the present invention.

Referring to FIG. 1, the method for producing hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to an embodiment of the present invention includes a mixture preparation (S10) step of mixing TiO ₂ particles, hydride, and mixed salt. , a crystallization (S20) step of producing a crystallized product by reacting the mixture at a temperature above the eutectic melting point of the mixed salt, and a powder obtaining (S30) of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder from the crystallized product. ) step.

In the method for producing hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to an embodiment of the present invention, a mixture is first prepared by mixing TiO ₂ particles, hydride, and mixed salt (S10).

The mixture preparation (S10) step may be a step for evenly mixing materials for reducing TiO ₂ and doping hydrogen with TiO ₂ particles.

The mixture preparation (S10) step is in detail a first mixture preparation (S11) step of mixing TiO ₂ particles and hydride to prepare a first mixture, and a second step of preparing a second mixture by adding a mixed salt to the first mixture. It may be done in the mixture preparation (S12) step.

The first mixture preparation (S11) step may be performed to add a hydride that reduces TiO ₂ to TiO ₂ .

Here, TiO ₂ is white TiO ₂ , and commercial or laboratory-synthesized TiO ₂ may be used. For example, P25 type TiO ₂ which is a mixture of anatase type and rutile type, TiO ₂ consisting of only anatase type, or TiO ₂ consisting of only rutile type can be used.

Hydride is a two-element compound formed by combining hydrogen with another element, and can be used as a reducing agent in the present invention. Specifically, hydride can induce oxygen deficiency on the TiO ₂ surface. Accordingly, TiO ₂ can be reduced to TiO _2-x form.

Additionally, hydride can dope hydrogen into oxygen-deficient TiO ₂ (TiO _2-x ). Specifically, hydrogen of hydride may be doped into oxygen-deficient sites or interstitial defect sites of TiO ₂ . Accordingly, the reduced TiO ₂ may be formed as TiO _2-x, which is a hydrogen-doped form.

When reduced TiO ₂ is doped with hydrogen, the transfer of electrons becomes easier, reducing the phenomenon of electrons being trapped inside the material or recombining with holes when moving. Accordingly, the light absorption efficiency of TiO ₂ for visible light can be improved.

Hydrides include magnesium hydride (MgH ₂ ), sodium aluminum hydride (NaAlH ₄ ), sodium borohydride (NaBH ₄ ), lithium aluminum hydride (LiAlH ₄ ), calcium hydride (CaH ₂ ), and zirconium hydride ( ZrH ₂ ), titanium hydride (TiH ₂ ), vanadium hydride (VH ₂ ), sodium hydride (NaH), lithium hydride (LiH), potassium hydride (KH), rubidium hydride (RbH), cesium hydrogen. One or more species selected from the group consisting of hydride (CsH) and magnesium iron hydride (Mg ₂ FeH ₆ ) may be used.

TiO ₂ particles and hydride may be mixed at a molar ratio of 1:1 to 1:20.

If TiO ₂ particles and hydride are mixed at a molar ratio of less than 1:1, the amount of hydride, which is a reducing agent, is relatively small, so reduction of TiO ₂ may not occur properly. Conversely, when TiO ₂ particles and hydride are mixed at a molar ratio exceeding 1:20, the hydride creates too many oxygen deficiency sites in TiO ₂ , increasing the absorbance of visible light, while the number of electron and hole recombinations also increases. Photocatalyst performance may deteriorate due to the formation of new phases or new phases.

At this time, depending on the type of hydride used, the molar ratio in which TiO ₂ particles and hydride are mixed may vary.

For example, when TiH ₂ is used as the hydride, TiO ₂ and TiH ₂ may be mixed at a molar ratio of 1:1 to 1:3.

TiO ₂ particles and hydride can be mixed using equipment such as milling or mixer, but are not limited to this.

When the preparation of the first mixture of TiO ₂ particles and hydride is completed, the mixed salt is added to the first mixture to prepare the second mixture (S12).

The second mixture preparation (S12) step may be performed to add a mixed salt to the first mixture to help the reduction reaction of TiO ₂ occur at a low temperature and for a short time.

It is appropriate that the mixed salt is selected to have a eutectic melting point of less than 700°C.

Specifically, the mixed salt is lithium chloride (LiCl), sodium chloride (NaCl), potassium chloride (KCl), rubidium chloride (RbCl), cesium chloride (CsCl), lithium sulfate (Li ₂ SO ₄ ), and sodium sulfate (Na ₂ SO ₄ ), potassium sulfate (K ₂ SO ₄ ), and potassium phosphate (K ₃ PO ₄ ). Two or more species selected from the group consisting of may be used.

The mixed salt may be appropriately selected and used depending on the type of hydride used in the first mixture preparation (S11) step.

Meanwhile, the mixed salt and the first mixture may be mixed at a mass ratio of 5:1 to 120:1.

If the mass ratio of the mixed salt and the first mixture is less than 5:1, the heat transfer efficiency of the mixed salt may decrease and the heat treatment time may be prolonged. Conversely, when the mass ratio of the mixed salt and the first mixture is 120:1, the melting point becomes too low, which may weaken the bond within the powder.

At this time, the mixed mass ratio of the mixed salt and the first mixture may be different depending on the type and amount of hydride used in the first mixture, and the type of mixed salt.

For example, when TiH ₂ is mixed as a hydride at a molar ratio of 1:1 to 1:3, it may be mixed at a mass ratio of 7:1 to 20:1.

The mixed salt and the first mixture can be mixed using equipment such as a mill or mixer, but are not limited to this.

Once the preparation of the second mixture is completed, a crystallized product is prepared by reacting at a temperature above the eutectic melting point of the mixed salt (S20).

The crystallization (S20) step may be performed to induce a reduction reaction of TiO ₂ to form crystals of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder.

The crystallization (S20) step may include a heat treatment (S21) step of heat-treating the second mixture and a cooling (S22) step of cooling the heat-treated second mixture.

The heat treatment (S21) step may be performed to induce a reduction reaction of TiO ₂ .

The heat treatment (S21) step can be performed by placing the second mixture in a reaction vessel such as an alumina crucible, charging it into the reaction furnace, and then heating the reaction furnace.

At this time, heat treatment can be performed in various ways, such as heating by burning fuel, heating by using physical characteristics of electricity such as electrical resistance, electromagnetic induction, and discharge, and heating by injecting gas.

Meanwhile, the heat treatment (S21) step may be performed at a temperature higher than the eutectic melting point of the mixed salt.

Here, the eutectic melting point of the mixed salt refers to the point where the two components are completely dissolved and mixed in the liquid state without forming a solid solution. Specifically, it refers to the fact that all mixed salts can exist in a liquid state.

Since the mixed salt of the present invention may be selected to have a eutectic melting point of less than 700°C, the heat treatment (S21) step may be performed at a temperature of 700°C or higher. Specifically, the heat treatment (S21) step may be performed at a temperature of 700° C. or higher for 3 hours or more.

If the heat treatment is performed at a temperature of less than 700°C for less than 3 hours, the mixed salt may not melt properly and the reduction of TiO ₂ may not occur smoothly.

A cooling (S22) step may be performed to form crystals of the product produced by heat treatment.

The cooling (S22) step can be performed by cooling the reactor using gas, cooling it naturally, etc.

When the preparation of the crystallized product is completed, hydrogen-doped reduced titanium oxide (TiO _2-x ) powder is obtained from the crystallized product (S30).

The powder obtaining (S30) step may include a washing (S31) step of washing the crystallized product, a filtration (S32) step of filtering the washed crystallized product, and a drying (S33) step of drying the filtered crystallized product. You can.

A washing (S31) step may be performed to dissolve water-soluble salts remaining in the crystallized product.

The washing (S31) step may be performed by immersing the crystallized product in distilled water.

A filtration (S32) step may be performed to filter out insoluble product particles in the crystallized product.

The filtration (S32) step can be performed by natural filtration, suction filtration, etc.

The drying (S33) step may be performed to remove moisture from the powder.

The drying (S33) step can be performed by drying in an oven or natural drying.

In some embodiments, the method for producing hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention may further include a post-treatment (S40) step of heat treating the filtered crystallized product.

A post-treatment (S40) step may be performed to prepare the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder into a more stable phase.

The post-treatment (S40) step may be performed by heat treatment at a temperature of 300°C or higher for 1 to 3 hours.

As the post-treatment (S40) step is performed, the thermal and chemical stability of the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder may be improved. In this case, the problem of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder easily changing phase at a certain temperature and pressure can be prevented, and thus the specific surface area can be reduced to prevent light absorption from falling. .

The method for producing hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention includes the steps of mixing TiO ₂ particles, hydride, and mixed salt to prepare a mixture, and reacting the mixture at a temperature above the eutectic melting point of the mixed salt. Since it includes the step of preparing a crystallized product, an excellent photocatalyst can be manufactured with significantly improved light absorption performance for ultraviolet and visible light, photocatalytic performance, and catalyst stability.

Specifically, the size of the band gap can be reduced through oxygen deficiency in TiO ₂ and the generation of Ti ³⁺ ions, and the recombination of electrons and holes can be prevented through hydrogen doping.

In addition, the method for producing hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention includes preparing a mixture by mixing TiO ₂ particles, hydride, and mixed salt, and mixing the mixture at a temperature above the eutectic melting point of the mixed salt. Since it includes the step of reacting to produce a crystallized product, the ease of processing can be improved.

Specifically, since the heat treatment is performed by adding a mixed salt and heating, hydrogen-doped reduced titanium oxide (TiO _2-x ) powder can be produced at a lower temperature and in a faster time.

In addition, since hydride is added to heat and reduce, hydrogen can be doped at the same time as oxygen deficiency and Ti ³⁺ ion generation, so the process time can be shortened compared to the manufacturing method of separately coating a material that improves light absorption. .

Furthermore, the method for producing doped reduced titanium oxide powder (TiO _2-x ) of the present invention can easily control the size and shape of the titanium oxide powder depending on the type and mixing ratio of the hydride and the mixed salt.

Specifically, by controlling the size of the band gap of titanium oxide, the number of oxygen vacancies, and substitution of hydrogen for oxygen vacancies, etc., depending on the type and mixing ratio of hydride and mixed salt, solar light absorption performance, photocatalytic performance, and catalyst stability, etc. can be easily controlled.

The hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention has an oxygen-deficient structure. Specifically, TiO ₂ is reduced and It has a surface oxygen-depleted structure. When oxygen in TiO ₂ is deficient, a change occurs in the oxidation number of Ti. Specifically, Ti ⁴⁺ changes to Ti ³⁺ . Since the energy level of Ti ³⁺ is lower than that of Ti ⁴⁺ , the band gap of Ti ³⁺ may be lower than that of Ti ⁴⁺ . Accordingly, the light absorption efficiency of TiO ₂ for visible light can be improved.

Meanwhile, the color of oxygen-deficient titanium oxide (TiO _2-x ) changes depending on the degree of oxygen deficiency on the surface. The color changes from light yellow, yellow, gray, dark gray, and black depending on the degree of oxygen deficiency. The reason why the color change occurs in this order is because the more titanium oxide is reduced, that is, the more oxygen defects there are in titanium oxide, the area that can absorb light gradually moves toward longer wavelengths.

In addition, the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention has a structure in which hydrogen is doped at the oxygen-deficient site. Since the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention is doped with hydrogen at oxygen-deficient sites, the recombination of electrons and holes can be relatively reduced. Accordingly, the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder may have improved light absorption for visible light.

The hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention may have a particle diameter size of 5 nm to 100 μm.

The hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention has an optical absorption of 0.35 au or more in the visible light range (400 to 800 nm).

Additionally, the XRD spectrum of the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention may include (110), (101), and (211) diffraction peaks.

Since the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention has an oxygen-deficient and hydrogen-doped structure, it can relatively reduce the recombination of electrons and holes, and thus can be used not only in ultraviolet rays but also in visible light. Light absorption can be improved.

Hereinafter, the present invention will be described in detail through examples, comparative examples, and experimental examples.

However, the following examples and experimental examples only illustrate the present invention, and the content of the present invention is not limited to the following examples.

In the example, TiO ₂ , hydride, and mixed salt were mixed to prepare a mixture, then heat treated at a temperature above the eutectic melting point of the mixed salt, cooled, washed, filtered, and dried to prepare a powder. Here, P25 was used as TiO ₂ and TiH ₂ was used as the hydride. Additionally, KCl and NaCl were used as mixed salts.

Meanwhile, in the comparative example, TiO ₂ P25 without reaction treatment was used.

<Example 1>

Hydrogen-doped reduced titanium oxide (TiO _2-x ) powder was prepared through the following steps.

Step 1. Preparing a first mixture by mixing 1g each of TiO ₂ and TiH ₂

Step 2. Preparing a second mixture by mixing a mixed salt of 15 g each of KCl and NaCl with the first mixture.

Step 3. Raise the temperature from room temperature to 120℃ per hour and maintain the heat treatment temperature at 800℃ for 3 hours.

Step 4. Cooling using furnace cooling method

Step 5. Ultrasonic wash with approximately 1000ml of DI water for 30 minutes.

Step 6. Filter using filter paper

Step 7. After final washing with ethanol and acetone, dry in an oven at 80°C for 1 hour.

<Examples 2 to 5>

Hydrogen-doped reduced titanium oxide (TiO _2-x ) powder was prepared through the following steps.

Step 1. Preparing a first mixture by mixing 1g each of TiO ₂ and TiH ₂

Step 2. Preparing a second mixture by mixing a mixed salt of 15 g each of KCl and NaCl with the first mixture.

Step 3. Raise the temperature from room temperature to 120℃ per hour and maintain the heat treatment temperature at 800℃ for 3 hours.

Step 4. Cooling using furnace cooling method

Step 5. Ultrasonic wash with approximately 1000ml of DI water for 30 minutes.

Step 6. Filter using filter paper

Step 7. After final washing with ethanol and acetone, dry in an oven at 80°C for 1 hour.

Step 8. Heat treatment at 300℃, 350℃, 400℃, and 450℃ respectively.

<Example 6>

Step 1. Preparing the first mixture by mixing 1g of TiO ₂ and 3g of TiH ₂

Step 2. Preparing a second mixture by mixing a mixed salt of 15 g each of KCl and NaCl with the first mixture.

Step 3. Raise the temperature from room temperature to 120℃ per hour and maintain the heat treatment temperature at 800℃ for 3 hours.

Step 4. Cooling using furnace cooling method

Step 5. Ultrasonic wash with approximately 1000ml of DI water for 30 minutes.

Step 6. Filter using filter paper

Step 7. After final washing with ethanol and acetone, dry in an oven at 80°C for 1 hour.

<Experimental Example 1> Comparison of colors of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to hydride content

In Experimental Example 1, TiO ₂ and In order to compare the color of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to the mixing ratio of hydride, hydrogen-doped reduced titanium oxide (TiO _2-x) prepared in Examples 1 and 6 were compared. ) The powder was observed with the naked eye, and the results are shown in Figures 2a and 2b.

Figure 2a is a diagram showing hydrogen-doped reduced titanium oxide (TiO _2-x ) prepared in Example 1.

Figure 2b is a diagram showing hydrogen-doped reduced titanium oxide (TiO _2-x ) prepared in Example 6.

Referring to Figures 2a and 2b, the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder prepared according to Example 6 is the hydrogen-doped reduced titanium oxide (TiO _2- x) prepared according to Example 1. ) You can see that it has a darker black color than the powder. Through this, it can be seen that the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder has a darker black color as the hydride content increases. In addition, a dark color means that the absorbance of visible light is high, so it can be seen that the higher the hydride content, the higher the absorbance of visible light.

<Experimental Example 2> XRD analysis of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder

In Experimental Example 2, the crystal structure of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to the present invention was analyzed using an X-ray diffraction analyzer (XRD). X-ray diffraction analysis was performed using Cu-Kα (0.15406 ㎚) at a scan rate of 4 ° min ^-1 under conditions of 40 kV and 30 mA. Powder diffractometry data were evaluated using the JCPDS powder diffractometry database. The phase was identified based on whether the measured diffraction diagram matched the stored line pattern.

Figure 3 shows the results of XRD analysis of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to the present invention.

Referring to Figure 3, the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to the present invention had XRD peaks observed at 27.53° (110), 36.15° (101), and 54.40° (211). Through this, it can be seen that the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to the present invention has the strongest peak intensity of rutile (JCPDS: 00-004-0551).

That is, it can be confirmed that the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to the present invention originates from the rutile phase.

<Experimental Example 3> SEM image of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder

In Experimental Example 3, the size and shape of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to the present invention were analyzed using SEM images.

Figures 4a to 4d show SEM images of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to the present invention.

Referring to FIGS. 4A to 4D, it can be seen that the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to the present invention has a particle diameter size of 5 nm to 100 μm.

Spectrum 1
Element	Line Type	Apparent Concentration	K Ratio	Wt%	Wt% Sigma	Standard Label	Factory Standard	Standard Calibration Date
C	Kseries	2.89	0.02888	5.16	0.59	C Vit	Yes
O	KSeries	19.350	0.06561	31.41	1.08	SiO 2	Yes
Ti	Kseries	129.37	1.29367	63.42	1.07	Ti	Yes
Total				100.00

Referring to Figure 6a and [Table 1], it can be confirmed that Ti is contained at 63.42 wt% and O is contained at 31.41 wt%.

Figure 6b is the qualitative analysis result for Spectrum 2, and [Table 2] is the quantitative analysis result.

Spectrum 2
Element	Line Type	Apparent Concentration	K Ratio	Wt%	Wt% Sigma	Standard Label	Factory Standard	Standard Calibration Date
C	Kseries	3.99	0.3994	6.57	0.61	C Vit	Yes
O	KSeries	32.39	0.10901	41.48	0.95	SiO 2	Yes
Ti	Kseries	110.24	1.10239	51.95	0.90	Ti	Yes
Total				100.00

Referring to Figure 6b and [Table 2], it can be confirmed that Ti is contained at 51.95 wt% and O is contained at 41.48 wt%.

Figure 6c is the qualitative analysis result for Spectrum 3, and [Table 3] is the quantitative analysis result.

Spectrum 3
Element	Line Type	Apparent Concentration	K Ratio	Wt%	Wt% Sigma	Standard Label	Factory Standard	Standard Calibration Date
C	Kseries	5.71	0.05711	8.85	0.63	C Vit	Yes
O	KSeries	36.34	0.12229	42.84	0.90	SiO 2	Yes
Ti	Kseries	106.11	1.06106	48.31	0.82	Ti	Yes
Total				100.00

Referring to Figure 6c and [Table 3], it can be confirmed that Ti is contained at 48.31 wt% and O is contained at 42.84 wt%.

Figure 6d is the qualitative analysis result for Spectrum 4, and [Table 4] is the quantitative analysis result.

Spectrum 4
Element	Line Type	Apparent Concentration	K Ratio	Wt%	Wt% Sigma	Standard Label	Factory Standard	Standard Calibration Date
C	Kseries	4.95	0.04953	7.62	0.60	C Vit	Yes
O	KSeries	44.01	0.14810	47.53	0.81	SiO 2	Yes
Ti	Kseries	98.90	0.98901	44.86	0.74	Ti	Yes
Total				100.00

Referring to Figure 6d and [Table 4], it can be confirmed that Ti is contained at 44.86 wt% and O is contained at 47.53 wt%.

Through this, it was confirmed that the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder according to the present invention contains the same components as TiO ₂ , that is, Ti and O elements, in all crystal parts.

Experimental Example 4. Elemental analysis of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder

Figure 7 is a diagram showing the results of SEM elemental mapping of the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention.

Referring to FIG. 7, it can be seen that Ti and O are uniformly present in the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention.

At this time, C is derived by carbon tape on which the powder sample is placed, and Pt is derived by Pt coating, which is a pretreatment process for SEM analysis.

Experimental Example 5. UV-Vis analysis of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder

In Experimental Example 5, UV-Vis analysis of Examples 1 to 6 and Comparative Example was performed.

At this time, UV-Vis analysis was performed using an Ultraviolet-Visible-Near Infrared Spectrophotometer (CARY5000) manufactured by Agilent Technology.

Figure 8 is a diagram showing the results of UV-Vis analysis of hydrogen-doped reduced titanium oxide (TiO _2-x ) powder of the present invention.

Comparative Example 1 in FIG. 8 is a graph of TiO ₂ (P25) before reaction. Example 1 is a graph of hydrogen-doped reduced titanium oxide (TiO _2-x ) without post-treatment, and Examples 2 to 5 are hydrogen post-processed by heating to 300°C, 350°C, 400°C, and 450°C, respectively. This is a graph for doped reduced titanium oxide (TiO _2-x ). Example 6 is a graph of hydrogen-doped reduced titanium oxide (TiO _2-x ) prepared by mixing TiO ₂ and hydride at a molar ratio of 1:3.

Referring to FIG. 8, it can be seen that the comparative example absorbs light only in the ultraviolet region and hardly absorbs light in the visible region. On the other hand, in Examples 1 to 6, it can be seen that light is absorbed not only in the ultraviolet region but also in the visible region. Specifically, in the case of Examples 1 to 6, it can be seen that the optical absorption of visible light is 0.35 a.u. or more.

Through this, it can be seen that hydrogen-doped reduced titanium oxide (TiO _2-x ) powder has better light absorption characteristics of ultraviolet and visible light than TiO ₂ .

In addition, it can be seen that post-processed Examples 2 to 6 have almost similar light absorption characteristics compared to non-post-treated Example 1. Through this, it can be seen that the light absorption characteristics of the hydrogen-doped reduced titanium oxide (TiO _2-x ) powder are hardly deteriorated even when heat-treated to form a stable phase. That is, it can be confirmed that hydrogen-doped reduced titanium oxide (TiO _2-x ) powder, which has a stable phase and improved light absorption characteristics for ultraviolet and visible light, can be produced.

Meanwhile, when comparing Example 1 and Example 3, it can be confirmed that the light absorption of ultraviolet rays and visible light in Example 3, which has a higher mixing ratio of hydride, is higher than that in Example 1. Through this, it can be seen that the higher the mixing ratio of hydride, the improved light absorption of ultraviolet rays and visible light.

The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

The present invention is a photocatalyst technology and can be used in various industrial fields where photocatalysts are applied. For example, it can be used in various industrial fields such as environment, energy, and chemical manufacturing.

Claims (15)

1. A mixture preparation step of mixing TiO ₂ particles, hydride, and mixed salt;

   A crystallization step of reacting the mixture at a temperature above the eutectic melting point of the mixed salt to produce a crystallized product; and

   Comprising a powder obtaining step of obtaining TiO _2-x powder (where X is a rational number between 0.00001 and 2) from the crystallized product,

   Method for producing hydrogen-doped reduced titania (TiO _2-x ) powder.
2. According to paragraph 1,

   The hydride is

   Characterized by one or more selected from the group consisting of MgH ₂ , NaAlH ₄ , NaBH ₄ , LiAlH ₄ , CaH ₂ , ZrH ₂ , TiH ₂ , VH ₂ , NaH, LiH, KH, RbH, CsH and Mg ₂ FeH ₆ doing,

   Method for producing hydrogen-doped reduced titania (TiO _2-x ) powder.
3. According to paragraph 1,

   The mixed salt is

   Characterized in that it is two or more selected from the group consisting of LiCl, NaCl, KCl, RbCl, CsCl, Li ₂ SO ₄ , Na ₂ SO ₄ , K ₂ SO ₄ and K ₃ PO ₄ ,

   Method for producing hydrogen-doped reduced titania (TiO _2-x ) powder.
4. According to paragraph 1,

   The mixed salt is characterized in that the eutectic melting point is less than 700°C.

   Method for producing hydrogen-doped reduced titania (TiO _2-x ) powder.
5. According to paragraph 1,

   The mixture manufacturing step is

   A first mixture preparation step of mixing the TiO ₂ particles and hydride to prepare a first mixture; and

   Comprising a second mixture production step of preparing a second mixture by adding a mixed salt to the first mixture,

   Method for producing hydrogen-doped reduced titania (TiO _2-x ) powder.
6. According to clause 5,

   The first mixture manufacturing step is

   Comprising the step of mixing the TiO ₂ particles and the hydride at a molar ratio of 1:1 to 1:20,

   Method for producing hydrogen-doped reduced titania (TiO _2-x ) powder.
7. According to clause 5,

   The second mixture manufacturing step is

   Comprising the step of mixing the first mixture and the mixed salt at a mass ratio of 1:5 to 1:120,

   Method for producing hydrogen-doped reduced titania (TiO _2-x ) powder.
8. According to paragraph 1,

   The crystallization step is

   Including a heat treatment step and a cooling step,

   Method for producing hydrogen-doped reduced titania (TiO _2-x ) powder.
9. According to clause 8,

   The heat treatment step is

   Including the step of heat treatment at a temperature of 700°C or more for more than 3 hours,

   Method for producing hydrogen-doped reduced titania (TiO _2-x ) powder.
10. According to paragraph 1,

    The powder obtaining step is

    A washing step of washing the crystallized product;

    A filtration step of filtering the washed crystallized product; and

    comprising drying the filtered crystallized product,

    Method for producing hydrogen-doped reduced titania (TiO _2-x ) powder.
11. According to paragraph 1,

    The method for producing the hydrogen-doped reduced titania (TiO _2-x ) powder is

    Further comprising a post-treatment step of heat treating the dried product,

    Method for producing hydrogen-doped reduced titania (TiO _2-x ) powder.
12. According to clause 11,

    The post-processing step is

    Including heat treatment for 1 hour to 3 hours,

    Method for producing hydrogen-doped reduced titania (TiO _2-x ) powder.
13. According to paragraph 1,

    The hydrogen-doped reduced titania (TiO _2-x ) has a particle diameter size of 5 nm to 100 μm,

    Reduced titania (TiO _2-x ) powder doped with hydrogen.
14. According to paragraph 1,

    The hydrogen-doped reduced titania (TiO _2-x ) powder is

    0.35 a.u. in the visible light range (400 to 800 nm). Having a light absorption of more than

    Reduced titania (TiO _2-x ) powder doped with hydrogen.
15. According to paragraph 1,

    The hydrogen-doped reduced titania (TiO _2-x ) powder is

    has an XRD spectrum containing (110), (101) and (211) diffraction peaks.

    Reduced titania (TiO _2-x ) powder doped with hydrogen.

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