KR20190048647A - Photo catalyst composite and method for manufacturing thereof - Google Patents

Abstract

According to an aspect of the present invention, provided is a titanium oxide-based photocatalytic composite. In the titanium oxide-based photocatalytic composite, the titanium oxide is doped with carbon and pores having a size of 5 to 50 nm are included therein, and also, upconversion nanoparticles that absorb near-infrared wavelengths and emit wavelengths of ultraviolet or visible light bands can exist inside the pores. According to the present invention, there is an effect of improving photocatalytic activity by introduction of upconversion nanoparticles and doping of carbon.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a photocatalyst composite,

The present invention relates to a photocatalytic composite based on titanium oxide (TiO ₂ ) and a method for producing the same. More particularly, the present invention relates to a photocatalytic composite including up-converted nanoparticles and titanium oxide doped with carbon, the photocatalytic activity being enhanced by expanding an absorbable optical wavelength band, and a method for manufacturing the same.

Photocatalysts generally refer to catalysts that are activated by light energy to affect a specific rate of reaction. When a photocatalyst is irradiated with light having a predetermined wavelength, electrons and holes are formed on the surface of the photocatalyst, and a strong oxidation / reduction reaction is enabled by the electrons and the holes. Of the materials used as photocatalysts, titanium oxide (TiO ₂ ) has been widely used because of its excellent photoactivity, chemical and biological stability and durability. It has been developed as an environmentally friendly photocatalyst capable of decomposing, deodorizing, and sterilizing harmful substances.

However, in the conventional photocatalyst using titanium oxide, due to the band gap characteristic of titanium oxide, the wavelength of the ultraviolet region band is absorbed and can contribute to the photoactivity, and the wavelength of the visible ray region band has a disadvantage that the absorbance and the photocatalytic activity are extremely low have. It is necessary to extend the absorption wavelength band to the visible light and further to the near infrared ray portion.

The present invention has been made to solve the above-mentioned problems and it is an object of the present invention to provide a titanium oxide-based photocatalytic composite capable of sufficiently expanding the wavelength range of light capable of light activation to visible light or near-infrared light. However, these problems are exemplary and do not limit the scope of the present invention.

According to an aspect of the present invention, there is provided a titanium oxide-based photocatalytic composite.

In the titanium oxide-based photocatalytic composite, the titanium oxide is doped with carbon, and the inside of the titanium oxide absorbs pore and near infrared rays having a size of 5 nm to 50 nm and emits ultraviolet or visible light. Particles.

In the titanium oxide-based photocatalytic composite, the up-converted nanoparticles include a host and a doping material doped to the host. Said host is a _{LiYF 4, NaY, NaYF 4,} NaGdF 4 and CaF in any one or more is selected, the doping material of ₃ ³⁺ Sm, Nd ^{+ 3,} Dy ^{+ 3,} Ho ^{+ 3} and Yb ^{+ 3,} Er ^{3 +} , Ho ^{3 +} , Tm ^{3 +,} and Eu ^{3 +} and Gd ^{3 +} can be selected.

For example, the upconverted nanoparticles may include beta-NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} , Gd ^{3 +} particles.

According to another aspect of the present invention, there is provided a method of manufacturing a titanium oxide-based photocatalytic composite.

The method for preparing the titanium oxide-based photocatalytic composite includes: preparing a titanium oxide sol-gel precursor, a self-assembled block copolymer micelle solution, and an up-converting nano- Preparing a solution in which particles are mixed; Coating the solution on a predetermined substrate to form a self-assembled block copolymer template comprising titanium oxide; And subjecting the self-assembled block copolymer template to a curing treatment and a heat treatment to form a photocatalytic composite comprising titanium oxide.

A method for manufacturing a titanium oxide-based photocatalytic composite, comprising the steps of: forming a pore having a size of 5 nm to 50 nm inside the titanium oxide while the self-assembled block copolymer is removed in the curing treatment and the heat treatment step; And carbon generated by carbonization of the assembled block copolymer is doped in the titanium oxide.

The titanium oxide sol-gel precursor is prepared by adding a strong acid to a solution in which a titanium oxide precursor is dissolved, wherein the titanium oxide precursor is titanium tetraisobutyrate Titanium tetra iso-propoxide, titanium tetrabutoxide, and titanium alkoxide may be included.

A method of preparing a titanium oxide-based photocatalyst composite, wherein the self-assembled block copolymer micelle solution is a polyethylene oxide-block-polypropylene oxide-b-Polyethylene oxide (P123) or Or a solvent which is selectively dissolved in at least one block of poly (styrene-b-ethylene oxide) (PS-b-PEO).

A method for producing a titanium oxide-based photocatalytic composite, wherein the up-converted nanoparticle comprises a host and a doping material doped to the host, wherein the host is selected from the group consisting of LiYF ₄ , NaY, NaYF ₄ , NaGdF _4, and CaF ₃ with one or more is selected, and said doping material is Sm ^{3 +,} Nd ^{3 +,} Dy ^{3 +,} Ho ^{3 +} and Yb ^{3 +,} Er ^{3 +,} Ho ^{3 +,} Tm ^{3 +} and Eu ^{3 +,} Gd ^{3 +} May be selected.

A method for producing a titanium oxide-based photocatalytic composite, wherein the upconverted nanoparticle may include? -NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} , and Gd ^{3 +} particles.

A method of making a titanium oxide-based photocatalytic composite, the curing treatment comprising irradiating the surface of the self-assembled block copolymer template with ultraviolet light in vacuum.

The titanium oxide-based photocatalytic composite may be prepared by heating the titanium oxide-based photocatalyst composite at a temperature higher than the carbonization temperature of the self-assembled block copolymer in an inert gas atmosphere.

According to an embodiment of the present invention, as described above, pores are formed to produce a photocatalytic composite containing up-converted nano-particles and titanium oxide doped with carbon. Further, according to the present invention, there is an effect of improving the photocatalytic activity by introduction of up-converted nanoparticles and doping of carbon. Of course, the scope of the present invention is not limited by these effects.

1 is a flowchart illustrating a method of manufacturing a photocatalytic composite according to an embodiment of the present invention.
2 (a) and 2 (b) are conceptual diagrams showing changes in energy level of up-converted nanoparticles according to an embodiment of the present invention.
3 is a schematic view showing a method of manufacturing a photocatalyst structure according to an embodiment of the present invention and comparative examples.
4 (a) to 4 (d) are the results of analysis of the characteristics of the up-converted nanoparticles used in the experimental examples of the present invention.
5 (a) to 5 (f) are SEM and TEM photographs showing the surface of the photocatalyst structure according to Experimental Examples and Comparative Examples of the present invention.
6 (a) and 6 (b) are X-ray diffraction and Raman analysis results of the photocatalyst structure according to Experimental Examples and Comparative Examples of the present invention.
7 is a graph showing the results of UV-Vis absorption spectra of the photocatalyst structure according to Experimental Examples and Comparative Examples of the present invention.
8 (a) to 8 (d) are graphs showing changes in concentration as the nitrobenzene is decomposed by the photocatalyst structure according to Experimental Examples and Comparative Examples of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, Is provided to fully inform the user. Also, for convenience of explanation, the components may be exaggerated or reduced in size.

1 is a flowchart showing a method of manufacturing a photocatalytic composite based on titanium oxide (TiO ₂ ) according to an embodiment of the present invention. Hereinafter, a method for producing a photocatalytic composite will be described with reference to FIG.

First, a step of preparing a solution containing a titanium oxide sol-gel precursor, a self-assembled block copolymer micelle solution and up-converted nanoparticles absorbing a near-infrared wavelength and emitting ultraviolet band or visible light band wavelength is prepared (S10).

Illustratively, the step (S10) comprises the steps of (S11) preparing a first solution by mixing a titanium oxide sol-gel precursor and a self-assembled block copolymer, as shown in Figure 1, And mixing the first solution with the up-converted nanoparticles to prepare a second solution (S12). Of course, the step (S10) may be performed by simultaneously mixing a titanium oxide sol-gel precursor, a self-assembled block copolymer and an up-converted nanoparticle.

Referring to FIG. 1, in step S11 of producing the first solution, a titanium oxide sol-gel precursor is prepared by adding a strong acid to a solution prepared by dissolving a titanium oxide precursor, and diluting and stirring .

The titanium oxide precursor may be, for example, titanium tetraisopropoxide (Ti (Oi-Pr) ₄ , TTIP) represented by the following formula (1). Other examples include titanium tetrabutoxide, titanium alkoxide, and the like. This titanium oxide precursor is dissolved in a solvent such as alcohol, isopropanol, etc. to prepare a titanium oxide-precursor solution. A titanium oxide sol-gel precursor can be prepared by adding a strong acid such as concentrated hydrochloric acid to the titanium oxide precursor solution thus prepared.

Self-assembled block copolymers are multi-block copolymers, which allow phase separation of the polymer blocks within the molecule, but are covalently bonded and thus have limited phase separation. Thus, self-assembled block copolymers can form periodically ordered nanostructures such as spheres, cylinders, lamella, and the like. The nanostructure formed by the self-assembled block copolymer is a thermodynamically stable structure, so that the nanostructure is spontaneously formed. By controlling the relative composition and molecular weight of each block, the shape and size of the nanostructures can be controlled.

The self-assembled block copolymer may be, for example, a polyethylene oxide-block-polypropylene oxide-b-Polyethylene oxide (P123) such as the following formula (2).

In the formula (2), x may be an integer of 18 to 22, y may be an integer of 65 to 75, and z may be an integer of 18 to 22.

As another example, poly (styrene-b-ethylene oxide, PS-b-PEO) may be used.

Such self-assembled block copolymers may be prepared using a solvent that is selectively soluble in at least one of the blocks of the self-assembled block copolymer. For example, in the case of P123, a micelle solution can be prepared using any solvent capable of dissolving P123, such as ethanol.

 In the case of PS-B-PEO, micellar solution solutions can be prepared using toluene, chloroform, dimethylformamide (DMF), benzene, or the like.

Preferably, a solvent selected from PPO (polypropylene oxide) is used for P1213, and a solvent selected for PEO (polyethylene oxide) is used for PS-B-PEO. .

The thus prepared titanium oxide sol-gel precursor and the self-assembled block copolymer micelle solution are mixed to prepare a first solution.

Next, a second solution (S21) is prepared by mixing the first solution with the up-converted nanoparticles absorbing the near-infrared wavelength and emitting a visible light wavelength.

Upconversion Nanoparticle (UCN) is a nanoparticle that absorbs light of relatively low energy and emits it as light of high energy. The upconverted nanoparticles consist of a host and a doping material doped to the host. As the host, any one or more of LiYF ₄ , NaY, NaYF ₄ , NaGdF _4, and CaF ₃ may be selected. As the doping material is ^{Sm 3 +, Nd 3 +,} Dy 3 +, Ho 3 + and ^{Yb 3 +, Er 3 +,} Ho 3 +, Tm 3 + and Eu ^{3 +,} Gd ^{3 +,} select at least one of a . For example, β-NaYF ₄ : Yb ³⁺ , Tm ³⁺ , Gd ³⁺ particles may be used as the up-converted nanoparticles.

Next, the second solution is coated on a predetermined substrate to form a self-assembled block copolymer template containing titanium oxide (S30). A coating method using a wet method is used for the coating, and spin coating can be typically performed. However, the present invention is not limited thereto, and dip coating, gravure coating and the like may be applied. As the substrate, glass, silicon, a metal material, a polymer material, and the like can be selected variously according to the purpose and use of the substrate.

Next, the self-assembled block copolymer template is cured and heat-treated to form a titanium oxide-based photocatalytic composite (S40). The titanium oxide-based photocatalytic composite refers to a structure in which titanium oxide is used as a platform or a matrix and a heterogeneous material is compounded in the titanium oxide.

The curing treatment includes irradiating ultraviolet (UV) to the self-assembled block copolymer template in a vacuum atmosphere to cause the self-assembled block copolymers to cross-cure to one another.

Upon completion of the curing process, heat energy is applied to the cured self-assembled block copolymer template to perform heat treatment. For example, the heat treatment may be performed in an inert gas atmosphere such as argon (Ar) after being charged into the heat treatment furnace.

At this time, the heat treatment induces carbonization of the cured block copolymer by heating to a temperature higher than the carbonization temperature of the self-assembled block copolymer.

The carbon generated in the step of carbonizing the block copolymer is doped into the titanium oxide crystal structure constituting the structure. When carbon dioxide is doped into titanium oxide, a new energy level is formed between the valence band and the conduction band of titanium oxide, thereby reducing the band gap of titanium oxide. Therefore, it has the effect of expanding the light utilization range of titanium oxide to a larger wavelength region band than the conventional one.

On the other hand, a step of removing the hydrophobic block of the block copolymer together with the carbonization of the block copolymer is carried out. Thus, pore having a size of 5 nm to 50 nm is generated at a portion where a part of the block copolymer is removed.

Therefore, according to the embodiment of the present invention, the block copolymer not only functions as a template for pore formation but also functions as a carbon source or a carbon precursor for doping carbon in titanium oxide.

Further, the titanium oxide photocatalytic composite according to an embodiment of the present invention includes up-converted nanoparticles. The upconverted nanoparticles may be present in the pores in the titanium oxide porous structure. The upwardly varying nanoparticles present in the pores absorb light in the near infrared region and emit ultraviolet or visible light. As the light in the ultraviolet or visible light band is absorbed by titanium oxide, the function of titanium oxide as a photocatalyst is activated. This will be described in more detail with reference to Figs. 2 (a) and 2 (b).

2 (a) shows the energy level change of the titanium oxide photocatalytic composite according to the embodiment of the present invention when β-NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} , and Gd ^{3 +} particles are used as the upwardly changing nanoparticles FIG. 2B is a conceptual diagram illustrating the energy transfer between the upward Yb ^{3 +} , Tm ^{3 +} and carbon-doped titanium oxide (mC-TiO ₂ ).

2 (a) and 2 (b), the up-converted nanoparticles containing β-NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} , and Gd ^{3 +} absorb the near-infrared (NIR) . The absorbed near infrared wavelengths can transfer energy to electrons present in the orbitals of Yb ^{3 +} , Tm ^{3 +} and Gd ^{3 +} elements. Near infrared rays having the same energy as the orbital energy level, for example, a near infrared laser having a wavelength of 980 nm, are transmitted to the electrons existing in the orbitals, electrons of the orbitals can be excited. The excited electrons can emit energy at multiple wavelengths, for example emitting wavelengths in the ultraviolet or visible region and transmitting them to the titanium oxide. Titanium oxide absorbs the wavelength of the ultraviolet or visible light region, excites the electrons of the valance band VB to the conduction band (CB), and can exhibit photocatalytic activity. The excited electrons react with oxygen on the surface of titanium oxide to form oxygen anion (O ^2- ), and holes generated when electrons are excited react with the water present in the air to form hydroxyl radicals Neutral OH).

In the conventional titanium oxide photocatalyst, a wavelength (? <400 nm) having energy greater than the bandgap of titanium oxide had to be irradiated in order to generate a transition in the valance band of electrons, and in the region above the near- There is a problem that the light wavelength of the usable light is limited to a part of the ultraviolet ray or visible ray region because no light activity occurs with respect to light.

However, in the photocatalytic composite according to the embodiment of the present invention, And the up-converted nanoparticles serve as a medium for converting the near-infrared rays into ultraviolet rays or visible rays, so that the wavelength band in which the optical activity can be used is extended to the near-infrared rays. Particularly, the titanium oxide doped with carbon as in the embodiment of the present invention has a wider range of optical activity due to the light emitted from the up-converted nanoparticles as the size of the band gap to be excited by electrons decreases. For this reason, the photocatalytic composite according to the embodiment of the present invention can be expected to have a higher photocatalytic effect than the conventional photocatalytic composite.

Hereinafter, experimental examples are provided to facilitate understanding of the present invention. It should be understood, however, that the following examples are for the purpose of promoting understanding of the present invention and are not intended to limit the scope of the present invention.

A titanium oxide precursor solution was prepared by dissolving titanium tetra iso-propoxide (Ti (Oi-Pr) ₄ , TTIP), which is a titanium oxide precursor, in isopropanol. A titanium oxide sol-gel precursor was prepared by adding concentrated hydrochloric acid thus prepared.

Polyethylene oxide-b-Polypropylene oxide-b-Polyethylene oxide (P123) was used as a self-assembled block copolymer, and P123 was prepared as a titanium oxide sol- The first solution was prepared by mixing with the precursor.

Next, β-NaYF ₄ : Yb ³⁺ , Tm ³⁺ , and Gd ³⁺ particles were added as the up-converted nanoparticles to the first solution to prepare a second solution.

The β-NaYF4: Yb3 +, Tm3 +, and Gd3 + particles used in the experimental examples were prepared by hydrothermal treatment. NaOH solution (3 ml), ethanol (10 ml) and oleic acid (10 ml) were put into a Teflon reactor. The rare earth chloride, Gd3 +, Y3 +, Yb3 +, Tm3 + (0.2M, 30: 51.8: 18: 0.2) was dissolved in NH4F (2M, 2 ml) and mixed with the solution with vigorous stirring for 30 minutes. The chamber was sealed and heat treated at 200 &lt; 0 &gt; C for 4 hours and then transferred to an autoclave made of stainless steel. After cooling to room temperature, the particles produced by centrifugation were collected and washed sequentially with ethanol and water.

Next, the second solution was stirred for 30 minutes, and then dropped on an FTO (F-doped Tin Oxide) substrate and spin-coated at 2000 rpm for 60 seconds.

Subsequently, the substrate coated with the second solution was placed in a vacuum container, and ultraviolet rays of 254 nm wavelength were irradiated at an energy intensity of 25 W / cm 2 for 1 hour to cure the self-assembled block copolymers to each other. After the above process was completed, the thin film was charged into an electric furnace and heated at 600 ° C for 1 hour in an argon (Ar) atmosphere to induce carbonization of the cured block copolymer. By performing these steps, a carbon-doped titanium oxide photocatalytic composite (hereinafter referred to as 'mC-TiO ₂ / UCN') having pores therein and containing up-converted nanoparticles could be produced.

As Comparative Example 1 for comparing characteristics with this Experimental Example, the first solution was coated on an FTO substrate, calcined at a temperature of at least 450 캜 for 4 hours or more in the atmosphere, and titanium oxide photocatalyst having pores therein (shown below 'mC-TiO _2') structure was prepared. As Comparative Example 2, except that β-NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} , and Gd ^{3 +} nanoparticles were not added to the first solution, (Hereinafter referred to as &quot; mC-TiO ₂ &quot;) were prepared.

3 shows a simplified view of a manufacturing method according to Comparative Example 1 (m-TiO ₂ ), Comparative Example 2 (mC-TiO ₂ ) and Experimental Example (mC-TiO ₂ / UCN).

FIG. 4 (a) shows the results of X-ray diffraction analysis of the upconverted nanoparticles used in the experimental example of the present invention. Referring to Figure 4 (a), β-NaYF 4: Yb 3 +, Tm 3 +, (100), (110) inherent peak of Gd ^{3 +,} (101), (200), (111), ( 201, 210, (002), (300), (221), (112), and (220) diffraction peaks were observed, from which the particles were identified as β-NaYF ₄ : Yb ³⁺ , Tm ³⁺ and Gd ³⁺ , respectively.

FIG. 4 (b) shows the SEM observation of the structure of the β-NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} , and Gd ^{3 +} nanoparticles. As a result, it can be seen that the nanoparticles have a rod-shaped uniform shape having a length of 290 nm to 310 nm and a diameter of about 35 to 45 nm.

FIG. 4 (c) shows photoluminescence spectroscopy results of β-NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} , and Gd ^{3 +} particles using a 980 nm laser beam. Referring to FIG. 4 (c), β 2 -NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} , and Gd ^{3 +} up-converted nanoparticles are doped with ¹ D ₂ ³ F ₄ (450 nm in the energy diagram of Yb ^{3 +} and Tm ^{3 +} ), ¹ G ₄ ³ H ₆ (474 nm), ¹ G ₄ ³ F ₄ (645 nm), ³ F ₃ ³ H ₆ (695 nm) and ³ H ₄ ³ H ₆ (802 nm) .

FIG. 4 (d) shows the results of confirming that the light of the visible ray band is emitted when the near-infrared wavelengths of β-NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} , and Gd ^{3 +} nanoparticles are examined.

Figure 5 (a) and 5 (d) are each in Comparative Example 1 (m-TiO ₂₎ SEM and a TEM analysis, Fig. 5 (b) and 5 (e) Comparative Example ₂ (mC-TiO 2) SEM and TEM, and FIGS. 5 (c) and 5 (f) are SEM and TEM analysis results of the experimental example (mC-TiO ₂ / UCN).

According to Figs. 5 (d), 5 (e) and 5 (f), since the titanium oxide structure was produced using the self-assembled block copolymer as the template in all of Comparative Example 1, Comparative Example 2 and Experimental Example, Are formed. However, referring to the results of surface observation of the specimen shown in the upper right corner of FIGS. 5 (b) and 5 (c), in the case of Comparative Example 2 and Experimental Example, since carbon was doped by the magnetic block copolymer, It can be seen that the surface color has a black surface.

5 (c) and 5 (f) in comparison with FIGS. 5 (a), 5 (b), 5 (d) ₄ : Yb ^{3 +} , Tm ^{3 +} , and Gd ^{3 +} particles.

6 (a) shows the XRD analysis results of Comparative Example 1, Comparative Example 2 and Experimental Example. Referring to FIG. 6 (a), the intrinsic X-ray diffraction peaks of titanium oxide (TiO ₂ ) correspond to (101), (103), (004), (112) , (211), (213), (204) and (220) diffraction planes were found in all the specimens, and thus all the specimens formed a structure based on titanium oxide. On the other hand, it can be confirmed that the X-ray diffraction peaks of β-NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} and Gd ^{3 +} particles are found only in the experimental examples.

6 (b) is a Raman spectrum analysis graph of Comparative Example 1 and Experimental Example. Referring to FIG. 6 (b), it can be seen that the peak of 1300 cm ^-1 D band and 1600 cm ^-1 G band, which are the intrinsic Raman spectrum peaks of carbon, appear only in the experimental examples. From this, it can be confirmed from the experimental example that titanium oxide is doped with carbon.

7 is a graph showing the results of ultraviolet-visible light absorption spectroscopic analysis of Comparative Example 1, Comparative Example 2 and Experimental Example.

In the case of a titanium oxide photocatalyst, the photocatalyst is activated by absorbing the ultraviolet wavelength and exciting the electrons of the valence band to the conduction band. Referring to FIG. 7, it can be seen that, in the case of Comparative Example 1, the absorbance is high at a wavelength of about 380 nm or less. This means that Comparative Example 1 exhibits the same activity as conventional titanium oxide photocatalyst.

On the other hand, in the case of Comparative Example 2, it can be seen that the absorbance is high at a wavelength of around 650 nm. When carbon is doped on the titanium oxide, a new energy level is formed between the valence band and the conduction band, thereby reducing the band gap energy of the titanium oxide. That is, the energy required to excite the electrons of the valence band to the conduction band is reduced, which means that the energy can be photocatalytically activated even if the energy is absorbed by long wavelength light, that is, visible light. Referring to FIG. 8, it can be seen that Comparative Example 2 absorbs visible light wavelengths.

In contrast, in the case of the experimental example, it can be seen that the wavelength exhibits a high degree of absorption at around 780 nm or less. From this, it can be confirmed that the β-NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} , and Gd ³⁺ particles contained in the experimental examples absorb the wavelength in the near infrared region.

8 is a graph showing changes in concentration at which nitrobenzene is decomposed when Comparative Examples 1, 2, and Experimental Examples were used as photocatalysts, and the amount of decomposition of nitrobenzene (NB) was measured according to various environments And photocatalytic activity was calculated.

8 (a), 8 (b), 8 (c), and 8 (d) are graphs showing the relationship between the wavelengths of ultraviolet light, ultraviolet light, ultraviolet light, , Comparative Example 1, Comparative Example 2, and Experimental Example The graph shows the concentrations of nitrobenzene decomposed by the specimen.

First, referring to FIG. 8 (a), titanium oxide does not exhibit photocatalytic activity in the state of blocking light, so that the amount of decomposition of nitrobenzene is very small. The difference in the concentration (C) after 3 hours compared with the initial concentration of nitrobenzene (C ₀ ) in the state where the light is blocked for 3 hours hardly appears. It can be seen that the photocatalyst is not activated due to blocking of light, and the spontaneous decomposition of nitrobenzene is very slow.

On the other hand, referring to FIG. 8 (b), the amount of decomposition of nitrobenzene was increased due to the photocatalytic activity of titanium oxide when the ultraviolet wavelength was examined. In particular, Comparative Example 2 and Experimental Example in which carbon is doped to improve the photocatalytic activity show decomposition of nitrobenzene in a larger amount than Comparative Example 1 in which carbon is not doped. This means that titanium oxide in which the band gap energy is reduced by carbon has improved photocatalytic activity.

Referring to FIG. 8 (c), when the near-infrared wavelength is examined, it can be seen that the experimental specimen containing the up-converted nanoparticles decomposes a greater amount of nitrobenzene than the other specimen. This means that the photocatalytic activity is improved because the up-converted nanoparticles absorb the near-infrared light having a wavelength that can not be absorbed by the carbon-doped titanium oxide to emit visible light. On the other hand, in Comparative Example 1 and Comparative Example 2 which did not contain the up-converted nanoparticles, the decomposition concentration of nitrobenzene was relatively small.

When the ultraviolet-infrared-near-infrared wavelengths shown in FIG. 8 (d) were sequentially measured, the photocatalytic activity was improved in the order of Comparative Example 1, Comparative Example 2, and Experimental Example. [Table 1] summarizes the measurement result of the concentration of nitrobenzene decomposed in FIG. In Table 1, the percentage (%) means the ratio of the initial nitrobenzene concentration (C ₀ ) to the concentration of nitrobenzene (C) decomposed by the photocatalytic complex after 3 hours.

division Comparative Example 1 Comparative Example 2 Experimental Example Block light 16% 18% 18% Ultraviolet wavelength 46% 60% 57% Near-infrared wavelength
(? = 980 nm) 32% 32% 55% Ultraviolet-infrared-near-infrared 50% 63% 83%

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken in conjunction with the present invention. Variations and changes are possible. Such variations and modifications are to be considered as falling within the scope of the invention and the appended claims.

Claims (10)

A photocatalyst comprising titanium oxide,
The titanium oxide is doped with carbon,
Converted nanoparticles which emit pore and near-infrared wavelengths having a size of 5 nm to 50 nm and emit wavelengths in an ultraviolet band or a visible light band,
Titanium oxide - based photocatalytic composite. The method according to claim 1,
Wherein the upconverted nanoparticle comprises a host and a doping material doped to the host,
At least one of LiYF ₄ , NaY, NaYF ₄ , NaGdF ₄ and CaF ₃ is selected as the host
As the doping material is ^{3 +} Sm, Nd ^{+ 3,} Dy ^{+ 3,} Ho ^{+ 3 + 3,} and Yb, Er ^{+ 3,} Ho ^{+ 3,} Tm ^{+ 3,} and Eu ^{+ 3,} is selected more than any one of the Gd ³⁺ felled,
Titanium oxide - based photocatalytic composite. 3. The method of claim 2,
Wherein the upconverted nanoparticles comprise beta-NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} , Gd ^{3 +} particles,
Titanium oxide - based photocatalytic composite. Preparing a solution containing a titanium oxide sol-gel precursor, a self-assembled block copolymer micelle solution and up-converted nanoparticles absorbing a near infrared ray wavelength and emitting ultraviolet band or visible ray band wavelength;
Coating the solution on a predetermined substrate to form a self-assembled block copolymer template comprising titanium oxide; And
And curing and heat-treating the self-assembled block copolymer template to form a photocatalytic composite comprising titanium oxide,
In the curing treatment and the heat treatment step, pores having a size of 5 nm to 50 nm are formed in the titanium oxide while the self-assembled block copolymer is removed,
Wherein the carbon produced by carbonization of the self-assembled block copolymer is doped to the titanium oxide.
A method for manufacturing a titanium oxide based photocatalytic composite. 5. The method of claim 4,
The titanium oxide sol-gel precursor may be, for example,
A solution prepared by adding a strong acid to a solution in which a titanium oxide precursor is dissolved,
Wherein the titanium oxide precursor comprises at least one of titanium tetra iso-propoxide, titanium tetrabutoxide, and titanium alkoxide.
A method for manufacturing a titanium oxide based photocatalytic composite. 5. The method of claim 4,
The self-assembled block copolymer micelle solution may be a solution of polyethylene oxide-block-polypropylene oxide-b-Polyethylene oxide (P123) or poly (styrene-block-ethylene oxide) (PS-b-PEO), wherein the solvent is selected from the group consisting of styrene-b-ethylene oxide (PS-b-PEO)
A method for manufacturing a titanium oxide based photocatalytic composite. 5. The method of claim 4,
Wherein the upconverted nanoparticle comprises a host and a doping material doped to the host,
At least one of LiYF ₄ , NaY, NaYF ₄ , NaGdF ₄ and CaF ₃ is selected as the host
As the doping material is ^{3 +} Sm, Nd ^{+ 3,} Dy ^{+ 3,} Ho ^{+ 3 + 3,} and Yb, Er ^{+ 3,} Ho ^{+ 3,} Tm ^{+ 3,} and Eu ^{+ 3,} is selected more than any one of the Gd ³⁺ felled,
A method for manufacturing a titanium oxide based photocatalytic composite. 8. The method of claim 7,
Wherein the upconverted nanoparticles comprise beta-NaYF ₄ : Yb ^{3 +} , Tm ^{3 +} , Gd ^{3 +} particles,
A method for manufacturing a titanium oxide based photocatalytic composite. 5. The method of claim 4,
Wherein the curing treatment comprises irradiating the surface of the self-assembled block copolymer template with ultraviolet light in a vacuum.
A method for manufacturing a titanium oxide based photocatalytic composite. 5. The method of claim 4,
Wherein the heat treatment is performed at a temperature above the carbonization temperature of the self-assembled block copolymer in an inert gas atmosphere,
A method for manufacturing a titanium oxide based photocatalytic composite.

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