KR20130131910A - Srtio3 photocatalytic particles preparation with enhanced photoactivity by spray pyrolysis method - Google Patents

Abstract

The present invention relates to a production method of strontium titanate particles with enhanced photoactivity by a spray pyrolysis method. Photocatalyst particles with remarkably improved porosity and the hydrogen generation speed compare to particles using conventional methods are produced through a continuous process by producing strontium titanate particles doped with nickel (Ni), tantalum (Ta), and lanthanum (La) using a spray pyrolysis method.

Description

(SrTiO3 photocatalytic particles preparation with enhanced photoactivity by spray pyrolysis method) which has improved photoactive properties by spray pyrolysis

The present invention relates to a method for producing strontium titanate photocatalyst particles improved in photoactive property by spray pyrolysis.

Researches on alternative energy resources have been continuously carried out due to the finite nature of energy resources such as coal and oil, and many studies have been conducted to utilize photocatalysts as energy resources using solar energy resources.

Photocatalyst is a material that promotes chemical reaction by using light energy. It is evaluated as having an unlimited possibility in that it can use infinite solar energy with light energy and solve environmental problems.

Photocatalysts perform various reactions including photocatalytic reactions, decomposition reactions of pollutants, etc. In addition, one of the important reactions is the reaction of the photocatalyst, which is activated by the light of water decomposition reaction, to decompose water molecules into hydrogen and oxygen. This water decomposition reaction is similar to the photosynthesis of plants, and has the advantage of being clean in that it uses water as a reactant and releases hydrogen and oxygen. As the photocatalyst is titanium dioxide (TiO _2), strontium titanate (SrTiO _3), tantalum sodium (NaTaO _3), zinc (ZnO), trioxide, tungsten oxide (WO _3), cadmium sulfide (CdS), selenide of cadmium (CdSe ), And cadmium teleonide (CdTe). Titanium dioxide and strontium titanate are typical photocatalysts. Titanium dioxide and strontium titanate are chemically and optically stable, have low cost, are not harmful to the human body and the environment, and have many advantages as photocatalysts, such as superior photocatalytic ability than photocatalysts of similar electrical properties. In the case of strontium titanate, the particles having a structure of perovskite (cubic system crystal structure) represented by ABO ₃ have a lattice structure with a stable and large photoactive region, and water and / or an aqueous solution Have been mainly used to produce hydrogen from hydrogen. With respect to the photocatalyst particles having the above-mentioned effects, it is known that three factors largely affect the photoactive property, which is an effective hydrogen production ability, by using solar energy. 2) the lattice structure, and 3) the surface morphology of the photocatalyst correspond to the factors affecting the photoactive properties.

However, in spite of having various advantages as described above, the photocatalyst particles can be used only in the ultraviolet region due to their band gap energy in application to the decomposition reaction of pollutants and contaminants using a water decomposition reaction and other photoactive reactions It has disadvantages.

Several techniques have been developed to solve this problem. A composite photocatalyst technology that expands the absorption range of the photocatalyst by biodegrading the photocatalyst with two different optically active regions, the ability to utilize the photocatalyst's electronics and the metal support to prevent recombination phenomenon, and the electron to make the photocatalyst effectively optically active The sacrificial reagents provided are those techniques. The most frequently used and effective technique is to apply Pt metal to the photocatalyst by the metal deposition technique. The patent has already been filed in Korea, and numerous papers have been published about it (Hyunwoong Park et al., J. Mater. Chem. Jiefang Zhu et al., Current Opinion in Colloid & Interface Science 14, 2009, 260-269), 2008, 18, 2379-2385; Yuh-Lang Lee et al., Chem. .

A representative example of the patent is Korean Patent Laid-Open No. 10-2009-0072745, entitled " Method for producing a mesoporous titanium dioxide photocatalyst for hydrogen generation ", and the efficiency of the photocatalyst is improved by supporting a Pt metal on the micrometer- There is an example.

The above techniques relate to the principle of photocatalysis, and the photocatalyst is a semiconductor material with a band gap energy. The band gap energy is the distance between the valence band (VB) and the conduction band (CB) of the material, and the semiconductor material must have this band gap energy so that electrons can move. This process is called exitation of electrons and electrons (e ^- ) usually exist in VB. When energy is received, they are excited and move to CB, leaving holes (h ⁺ ) in VB and electrons moving to CB It becomes movable. In the case of photocatalyst, it is light that supplies this energy. The band gap energy differs from photocatalyst to photocatalyst. The larger the band gap energy is, the larger the energy of light is to excite the photocatalyst. For example, TiO ₂ can be excited with light with a band gap energy of 3.2 eV above ultraviolet light and CdS with 2.4 eV above visible light. The photocatalyst improvement technology is a method to complement the disadvantages of the existing photocatalyst, and utilizes the properties of the bandgap and VB and CB.

In the case of titanium dioxide, which is widely known as a photocatalyst, various attempts have been made in order to exhibit a photoactive effect even in a visible light region in which a light-absorbing wavelength region has an ultraviolet region (below 380 nm). Typically, a new donor and acceptor are doped by doping other transition metals such as manganese (Mn), iron (Fe), cobalt (Co), ruthenium (Ru), iridium (Ir) Research has been carried out continuously so that a region can be generated in a forbidden band to exhibit optical activity in a visible light region, and the present invention is also an extension of the present invention.

The present invention relates to strontium titanate (SrTiO ₃ ) which is widely known as photocatalyst particles such as titanium dioxide. In order to exhibit the photoactive property in the visible light region as described above, a specific transition metal is doped to lower the band gap energy And more particularly to photocatalyst particles prepared by doping strontium titanate particles together with transition metal elements such as Ni (nickel), Ta (tantalum) and La (lanthanum).

When two transition metals are doped together into strontium titanate particles such as Cr / Ta, Cr / Sb, Ga / La, Na / Ta, Ni / Nb and Ni / Ta, (Kang HW et al., Int J Hydrogen Energy 2011; 36; 9496-504; Ishii T et al., J Photochem Photobiol A Chem 2004; 163; 181-6).

In addition to doping the transition metal atoms, the surface structure and the surface area of the photocatalyst particles also affect the photoactivity, and such properties are known to depend on the method of manufacturing the photocatalyst particles (Li et al., Int J Hydrogen Energy 2009; 34: 147-52). In particular, the photoactive property can be improved by forming new active sites on the surface of the photocatalyst particles. Conventionally, a strontium tantalate photocatalyst was prepared using a solid state reaction, which is one of batch-processes (Niishiro et al., Phys Chem Chem Phys 2005; 7, 2241-5).

In the present invention, strontium titanate photocatalyst particles having improved photoactive properties are prepared by spray pyrolysis, thereby forming particles having a uniform size distribution of a uniform composition and advantageous continuous-process in controlling the surface structure. The photocatalytic particles are synthesized by spray pyrolysis, which is a type of photocatalyst.

An object of the present invention is to solve the above-mentioned problems and to provide a method for forming a particle having a uniform size distribution with a uniform composition and exhibiting photoactivity in a visible light region and improving the photoactive property by spray pyrolysis, And a method for producing the strontium titanate photocatalyst.

Another object of the present invention is to provide strontium titanic acid photocatalyst particles improved in photoactive property produced by the above production method.

A first step of preparing a metal precursor solution by dispersing or dissolving a metal precursor material including strontium, titanium, nickel, tantalum and lanthanum element in a solvent; A second step of generating droplets using the spraying device of the metal precursor solution prepared in the first step; And a third step of heat treating the droplets generated in the above step to convert them into strontium titanate particles doped with nickel, tantalum, and lanthanum; The present invention also provides a method for producing strontium titanate photocatalyst particles having improved photoactive properties.

In one embodiment of the present invention, the metal precursor material of the first step is selected from the group consisting of strontium nitrate (Sr (NO ₃ ) ₂ ), titanium isopropoxide (Ti [OCH (CH ₃ ) ₂ ] ₄ ), nickel nitrate Ni (NO ₃ ) ₂ 6H ₂ O), tantalum ethoxide (Ta (OC ₂ H ₅ ) ₅ ) and vaginal scattering carbohydrate (La (NO ₃ ) ₃ 6H ₂ O).

In one embodiment of the present invention, the polymer solution may be a mixture of citric acid and ethylene glycol.

In one embodiment of the present invention, the droplet generated in the second step may be introduced into the reactor at a flow rate of 0.5 to 50 L / min.

In one embodiment of the present invention, the heat treatment performed in the third step may be performed at 500 to 1500 ° C.

In one embodiment of the present invention, the step of supporting the platinum catalyst on the surface of the produced strontium titanate photo-catalyst particles may be further carried out.

Further, the present invention provides strontium titanic acid photocatalyst particles improved in photoactive property produced by the above production method.

According to the present invention, by preparing the strontium titanic acid particles having improved photoactive properties by the spray pyrolysis method, the degree of porosity of the particles is greatly increased as compared with the particles produced by the conventional method, and the photocatalyst particles, . ≪ / RTI >

1 is a schematic view of a spray pyrolysis apparatus for producing strontium titanate photocatalyst particles having improved photoactive properties according to an embodiment of the present invention.
FIG. 2 is a flow chart of a method for producing strontium titanate photocatalyst particles having improved photoactive properties according to an embodiment of the present invention.
FIG. 3 is an X-ray diffraction (XRD) spectrum of strontium titanate photocatalyst particles doped with nickel, tantalum, and lanthanum, prepared according to an embodiment of the present invention.
FIG. 4 is an X-ray diffraction (XRD) spectrum of strontium titanate photocatalyst particles doped with nickel, tantalum, and lanthanum, prepared by adding a polymer solution according to an embodiment of the present invention.
5 is a scanning electron microscope (SEM) photograph of the photocatalyst particles manufactured according to an embodiment of the present invention.
FIG. 6 is a graph showing the change in crystallite size according to the amount of doping of a lanthanum element in a metal precursor solution in the strontium titanate photocatalyst particles doped with nickel, tantalum and lanthanum produced according to an embodiment of the present invention FIG.
FIG. 7 is a graph showing nitrogen adsorption isotherm results and pore size distribution of photocatalyst particles produced according to an embodiment of the present invention. FIG.
FIG. 8 is a graph showing hydrogen production efficiency of strontium titanate photocatalyst particles manufactured according to an embodiment of the present invention with respect to time.
9 is a graph showing the effect of hydrogen production according to the amount of lanthanum in the metal precursor solution in the strontium titanic acid photocatalyst particles produced according to an embodiment of the present invention.
10 is a graph showing hydrogen production effect of strontium titanate photocatalyst particles prepared by adding a polymer solution according to an embodiment of the present invention with time.
11 is a graph showing the effect of hydrogen production according to the amount of the polymer solution in strontium titanate photocatalyst particles prepared by adding a polymer solution according to an embodiment of the present invention.

The present invention provides a method for producing strontium titanate particles doped with nickel, tantalum and lanthanum elements exhibiting photoactive properties in visible and ultraviolet regions. Hereinafter, the present invention will be described in detail with reference to the flow chart of the manufacturing method of FIG.

Step 1: Preparation of precursor solution

The first step is a step of dispersing or dissolving a metal precursor material including strontium, titanium, nickel, tantalum and lanthanum element in a solvent to prepare a precursor solution.

At this time, the metal precursor material may be at least one selected from the group consisting of strontium nitrate (Sr (NO ₃ ) ₂ ), titanium isopropoxide (Ti [OCH (CH ₃ ) ₂ ] ₄ , nickel nitrate hydrate (Ni (NO ₃ ) ₂ 6H ₂ O) (Ta (OC ₂ H ₅ ) ₅ ) and vaginally scattered carbohydrate (La (NO ₃ ) ₃ 6H ₂ O) may be used, but the present invention is not limited thereto.

For example, strontium nitrate (Sr (NO ₃ ) ₂ ), titanium isopropoxide (Ti [OCH (CH ₃ ) ₂ ] ₄ ), nickel nitrate hydrate (Ni (NO ₃ ) ₂ 6H ₂ O) (Ta (OC ₂ H ₅ ) ₅ ) and vaginal scattering carbohydrate (La (NO ₃ ) ₃ 6H ₂ O) are dispersed and dissolved in a polar solvent such as water or alcohol, ≪ / RTI >

The size of the strontium titanate powder is determined according to the concentration of the precursor solution, and the total concentration of the precursor solution is preferably in the range of 0.1 to 1.0 M. When the total concentration of the precursor solution is lower than 0.1 M, the amount of strontium titanic acid powder to be produced is too small, and when it is higher than 1.0 M, the raw material is difficult to dissolve or disperse in distilled water.

Also, in addition to the precursor solution, a metal precursor material including a specific transition metal may be added.

The metal precursor material including the specific transition metal may be formed by changing the charge structure of the crystal lattice of the produced strontium titanate particle or by forming a new donor and acceptor region in a forbidden band As a result, it is possible to provide an effect of increasing the photoactivities including the rate of hydrogen generation of the photocatalyst particles.

In this case, the metal precursor material containing the specific transition metal used is nickel, tantalum and lanthanum type inorganic material. In the case of nickel, it is preferable to use nickel nitrate hydrate (Ni (NO ₃ ) ₂ 6H ₂ O). In the case of tantalum, column and the ethoxide _{(Ta (OC 2 H 5)} 5) preferably, in the case of lanthanum are preferable lanthanum nitrate hydrate _{(La (NO 3) 3 6H} 2 O). The molar ratio of the tantalum element to the nickel element is preferably maintained at 2: 1.

Step 2: Droplet  Spray

In the second step, the precursor solution prepared in the first step is introduced into a spray pyrolysis apparatus and atomized in a fine droplet using a spraying apparatus.

One embodiment of the spray pyrolysis apparatus may be configured as shown in FIG. 1, but it is not limited thereto, and may consist of a spray apparatus, a reactor, and a filtration apparatus.

As the atomizing device, an ultrasonic atomizing device, an air nozzle atomizing device, an ultrasonic nozzle atomizing device, a filter expanding droplet generating device, and the like can be used, and the ultrasonic nozzle atomizing device can be used in the manufacture of a submicron submicron fine strontium titanate powder And air nozzles and ultrasonic nozzle sprayers can produce large quantities of micron sized particles. The diameter of the droplet is preferably in a range of from 1 to 100 mu m. If the diameter of the droplet is less than 1 mu m, the generated particle size is too small, and if the diameter of the droplet exceeds 100 mu m, .

3rd step: From droplets  Conversion of strontium titanate particles with improved photoactive properties

In the third step, the droplet generated in the second step is introduced into the reactor of the spray pyrolysis apparatus, and the droplet is converted into strontium titanate particles by heat treatment in the reactor.

At this time, it is important to control the residence time of the droplets in the reactor in order to completely convert the droplets introduced into the reactor. The residence time in the reactor is an important factor of the flow rate of the carrier gas (carrier gas) and the temperature of the reactor to transport the droplet into the reactor. In particular, the flow rate of the carrier gas plays a most important role in determining the residence time in the reactor, and the optimal reactor temperature may vary depending on the amount of carrier gas flowing into the reactor. In the present invention, Lt; / RTI > to 2.4 seconds. ≪ RTI ID = 0.0 >

For this purpose, it is preferable that the produced droplet is introduced into the reactor at a flow rate of 0.5 to 50 L / min, and the reaction is carried out at a temperature of 500 to 1,500 ° C, more preferably 800 to 1,000 ° C.

In order to increase the photoactive effect of the strontium titanic acid particles synthesized by the spray pyrolysis method of the present invention, a platinum catalyst may be supported on the surface of the synthesized strontium titanic acid particles. In this case, chloroplatinic acid (H ₂ PtCl ₆ ) Can be used.

According to the present invention, by preparing the strontium titanic acid particles having improved photoactive properties by spray pyrolysis, the porosity of the particles is greatly increased compared with the particles prepared by the conventional solid phase reaction method, the hydrogen generation rate is remarkably increased, Photocatalyst particles with reduced induction period can be produced by a continuous process.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples are only the preferred embodiments of the present invention, and the present invention is not limited by the following Examples.

< Example  1 to 5>

Spray pyrolysis  Nickel, tantalum and lanthanum used Doped  Strontium titanic acid Photocatalyst  Manufacturing of particles

Strontium nitrate (Sr (NO ₃ ) ₂ ), titanium isopropoxide (Ti [OCH (CH ₃ ) ₂ ] ₄ ), nickel nitrate hydrate (Ni (NO ₃ ) ₂ 6H ₂ O) One sample (Examples 1 to 5) was prepared by mixing ethoxide (Ta (OC ₂ H ₅ ) ₅ ) and vaginal scattering carbohydrate (La (NO ₃ ) ₃ 6H ₂ O) .

The mixture was dispersed and dissolved in water to make the total concentration of the precursor solution 0.5 M.

The precursor solution was injected into the spraying apparatus of the spray pyrolysis apparatus of FIG. 1 to generate fine droplets of about 1 to 5 microns. The generated droplets were reacted at a reactor temperature of 500 to 1500 ° C, more preferably 800 to 1,000 ° C to prepare strontium titanate photocatalyst particles doped with nickel element.

At this time, the spraying apparatus used an industrial humidifier operating at a frequency of 1.7 MHz, and a carrier gas was used to efficiently feed a large amount of droplets generated by the four ultrasonic vibrators into the reactor, and air was used as the carrier gas Respectively. At this time, the flow rate was kept constant at 5 L / min, and a quartz reaction tube having a diameter of 30 mm and a length of 1.2 m was used as the reactor.

Strontium titanate photocatalyst particles were prepared in the same manner as in the Example except that no transition metal element was included (doped) as a control.

The mixing ratios of the raw materials (elements) used in Examples 1 to 5 and the control groups 1 and 2 are shown in Table 1 below.

division Sr Ti Ni Ta La Control 1 100 100 0 0 0 Control group 2 100 99.4 0.2 0.4 0 Example 1 99.95 99.4 0.2 0.4 0.05 Example 2 99.9 99.4 0.2 0.4 0.1 Example 3 99.8 99.4 0.2 0.4 0.2 Example 4 99.7 99.4 0.2 0.4 0.3 Example 5 99.6 99.4 0.2 0.4 0.4

The results of the X-ray diffraction (XRD) analysis of the photocatalyst particles obtained in Examples 1 to 5 and the control group 1 are shown in Fig. 3. The surface of the photocatalyst particles obtained in Example 4 was observed with a scanning electron microscope SEM). The results are shown in Fig. 5 (B). 5 (B) is a photograph of the surface of the produced strontium titanic acid photocatalyst particle enlarged 100,000 times.

X-ray diffraction  analysis

3 shows X-ray diffraction spectra of nickel, tantalum and lanthanum element-doped strontium titanate photocatalyst particles prepared by the spray pyrolysis method according to the present invention. Specifically, (a) any transition metal of the control group 1 is doped (B) strontium titanate photocatalyst particles doped with 0.2 mol% of nickel, 0.4 mol% of tantalum and 0.05 mol% of lanthanum in Example 1, (c) 0.2 mol of nickel of Example 2 , Strontium titanate photocatalyst particles doped with 0.4 mol% of tantalum and 0.1 mol% of lanthanum, (d) strontium titanate particles doped with 0.2 mol% of nickel, 0.4 mol% of tantalum and 0.2 mol% of lanthanum (E) strontium titanate photo-catalyst particles doped with 0.2 mol% of nickel, 0.4 mol% of tantalum and 0.3 mol% of lanthanum in Example 4, and (f) 0.2 mol% of nickel in Example 5, A strontium titanate photocatalyst doped with 0.4 mol% of rum and 0.4 mol% of lanthanum X-ray diffraction spectrum of the particles.

As shown in FIG. 3, it can be confirmed that strontium titanate particles were obtained on the (110), (111), (200), (211), (220) and (310) phases appearing on the X-ray diffraction spectrum. As the amount of the doped lanthanum element increases, the (110) phase shifts to a low 2? Value.

Scanning electron micrograph

5B is a scanning electron micrograph of the nickel element-doped strontium titanate photocatalyst particles produced by the spray pyrolysis method according to the present invention. Specifically, the nickel of Example 4 is 0.2 mol%, the tantalum And 0.4 mol% of boron and 0.3 mol% of lanthanum, respectively. As shown in FIG. 6, the surface roughness of the prepared particles increases as the surface roughness increases. This means that the surface structure can be changed by preparing the photocatalyst particles by the spray pyrolysis method according to the present invention it means.

Accordingly, the present invention can increase the photoactivity of the photocatalyst by greatly increasing the porosity of the particle surface by preparing strontium titanate photocatalyst particles doped with nickel, tantalum and lanthanum elements by spray pyrolysis.

These strontium titanate particles can be confirmed by XRD spectra and SEM photographs. However, in order to confirm the accurate strontium titanate phase, the residence time of the droplet in the reactor of the spray pyrolysis apparatus in the embodiment should be maintained within 0.024 seconds to 2.4 seconds.

For this, it was confirmed that the optimum reactor temperature and carrier gas flow rate of the spray pyrolysis apparatus in this embodiment were 800 ° C. and 5 L / min, respectively.

< Example  6 to 9>

Spray pyrolysis  Nickel, tantalum and lanthanum used Doped  Strontium titanic acid Photocatalyst  In the preparation of the particles, the polymer solution Additionally  The addition of strontium titanic acid Photocatalyst  Manufacturing of particles

Nickel, tantalum and lanthanum-doped strontium titanate photocatalyst particles were prepared in the same manner as in Examples 1 to 5 except that a polymer solution was additionally added to the precursor solution.

Specifically, the reaction conditions of the spray pyrolysis apparatus were the same as in Example 4, except that citric acid and ethylene glycol were used as the polymer solution. The polymer solution was used as an additive, and the molar ratio of citric acid to ethylene glycol was maintained at 1: 1 to give 100 (Example 6), 200 (Example 7), 300 (Example 8), 400 ) mol%. The mixing ratios of the raw materials (elements) used in Examples 6 to 9 are shown in Table 2 below.

division Sr Ti Ni Ta La Polymer solution Example 6 99.7 99.4 0.2 0.4 0.3 100 Example 7 99.7 99.4 0.2 0.4 0.3 200 Example 8 99.7 99.4 0.2 0.4 0.3 300 Example 9 99.7 99.4 0.2 0.4 0.3 400

X-ray diffraction  analysis

FIG. 4 shows an X-ray diffraction spectrum of strontium titanic acid photocatalyst particles obtained by additionally adding the polymer solution prepared in Examples 6 to 9 to a precursor solution. Specifically, when the amount of the polymer solution is (a) 100 mol (Example 7), (c) Example of adding 300 mol% of polymer solution (Example 8), (d) Addition of polymer solution Ray diffraction spectrum of strontium titanate photocatalyst particles doped with nickel, tantalum and lanthanum elements obtained in the case of adding 400 mol% (Example 9).

The amount of the polymer solution additionally added to the precursor solution can be confirmed that the position of the (110) phase of the strontium titanate photocatalyst particles obtained by the spray pyrolysis method is not changed. This means that even if the polymer solution is additionally added to the precursor solution, it does not affect the lattice structure of the obtained strontium titanic acid photocatalyst particles.

Injection Microscope Picture

Scanning electron micrographs of the strontium titanate photocatalyst particles doped with nickel and lanthanum elements prepared in Example 8 are shown in FIG. FIG. 5C is a photograph of the surface of the produced strontium titanate photo-catalyst particle enlarged 100,000 times. As shown in Fig. 5 (C), when compared with Fig. 6 (B) obtained in Example 4, it is confirmed that the obtained photocatalyst particles are broken and fragmented. This is because the polymer solution is decomposed in the spray pyrolysis process to generate gas.

< Experimental Example >

The crystal size according to the doping amount of the lanthanum element ( crystallite you ) change

6 is a graph showing the crystallite size change according to the doping amount of the lanthanum element in the metal precursor solution in the nickel, tantalum and lanthanum element-doped strontium titanate particles synthesized by spray pyrolysis.

Fig. 6 shows the crystal size change of the strontium titanic acid particles synthesized by the control group 2 and the examples 1 to 5. Fig. The crystal size was calculated using the Scherrer equation using the X-ray diffraction spectrum of FIG. As a result, the size of the strontium titanic acid particles obtained decreases as the doping amount of the lanthanum element increases, which is a result of the increase in the number of defects in the crystal lattice. This is because the defects inhibit crystal growth of the strontium titanate particle grating structure.

BET  Analysis Nitrogen isotherm adsorption  And pore size distribution

FIG. 7 shows the BET analysis results of the strontium titanate particles synthesized by the spray pyrolysis method and shows the results of nitrogen adsorption isotherm and pore size distribution of the produced strontium titanate photocatalyst particles . (A) nitrogen adsorption isotherms and (b) pore size distribution results of strontium titanate photocatalyst particles synthesized by Control 2, Example 3, Example 4, Example 5 and Example 8, respectively. (a) When the polymer solution was not additionally added, the surface area of the strontium titanate photocatalyst particles doped with 0.4 mol% of lanthanum in Example 5 was the largest (28.6 m 2 / g), and the polymer solution of Example 8 When 300 mol% was added, the surface area of strontium titanate photocatalyst particles was 39.0 m &lt; 2 &gt; / g. (b) The pore diameter of the strontium titanate photocatalyst particles not doped with the lanthanum element of the control 2 was the largest, and the pore size was decreased as the lanthanum element was doped. When the polymer solution of Example 8 was additionally added, it was found that the pore size was mainly 10 nm. The pore volume of the pores was found to increase as the volume of the pores increased as the lanthanum element was doped.

Table 3 shows the surface area of the strontium titanate particles prepared by the spray pyrolysis method and the solid phase reaction according to the present invention.

Types of particles Surface area (m 2 / g) Control group 2 22.7 Example 3 27.0 Example 4 28.2 Example 5 28.6 Example 8 39.0

Photoactivity measurement

In order to measure the photoactivity of the nickel, tantalum and lanthanum element-doped strontium titanate photocatalyst particles prepared according to the present invention, the following experiment was conducted.

The photoactivity was measured by adding the strontium titanic acid photocatalyst particles prepared in Examples 1 to 9 to a solvent (methanol: water = 20: 80 (v / v)) in the control 2 and then using a 300 W Xen And the hydrogen generation rate were measured and shown in Table 4 and Figs. 8 to 11.

division Sr
(mole%) Ti
(mole%) Ni
(mole%) Ta
(mole%) La
(mole%) Polymer solution
(mole%) Hydrogen generation rate
(μmol / hg) Control group 2 100 99.4 0.2 0.4 0 0 561.2 Example 3 99.8 99.4 0.2 0.4 0.2 0 812.6 Example 4 99.7 99.4 0.2 0.4 0.3 0 895.2 Example 5 99.6 99.4 0.2 0.4 0.4 0 832.8 Example 8 100 99.8 0.1 0.1 0.1 300 2305.7

Fig. 8 shows the hydrogen production effect of the strontium titanate photocatalyst particles produced by the control group 2 and the examples 1 to 5 with time. (b) a strontium titanate photo-catalyst particle (.cndot.) doped with 0.05 mol% of lanthanum in Example 1 (.cndot.); (c) the lanthanum of Example 2 (D) doped strontium titanate photocatalyst particles (e) doped with 0.2 mol% of lanthanum in Example 3, (e) strontium titanate photocatalyst particles doped with 0.3 mol% of lanthanum in Example 4 Titanium oxide photocatalyst particles (?) And (f) strontium titanate photocatalyst particles (?) Doped with 0.4 mol% of lanthanum in Example 5. 0.2 mol% of nickel, 0.4 mol% of tantalum and 0.3 mol% of lanthanum in Example 4 showed the highest photoactivity (895.2 μmol / hg) of the doped strontium titanate photocatalyst particles. And the induction period in Control 2 and Examples 1 to 5 were all 1 hour.

FIG. 9 is a graph comparing hydrogen generation rates according to the amounts of doped lanthanum elements in the strontium titanic acid photocatalyst particles prepared according to Control 2 and Examples 1 to 5. As shown in FIG. 8, 0.2 mol% of nickel, 0.4 mol% of tantalum and 0.3 mol% of lanthanum showed the highest photoactivities of the doped strontium titanate photocatalyst particles.

10 is a graph showing the photoactivities of strontium titanate photocatalyst particles prepared in Examples 6 to 9 according to the amount of the polymer solution added to the precursor solution. Specifically, (a) 100 mol of the polymer solution of Example 6 (A), (b) when the polymer solution of Example 7 was added in an amount of 200 mol%, (c) when the polymer solution of Example 8 was added in an amount of 300 mol% ) In the case where 400 mol% of the polymer solution of Example 9 is added (), the hydrogen generation effect with time is shown. When the polymer solution of Example 8 was added in an amount of 300 mol%, the strontium titanic acid photocatalyst particles obtained showed the highest optical activity (2305.7 μmol / hg). It was found that the photoactivity of the strontium titanate photo-catalyst particles obtained by Example 8 was increased about 2.6 times, except that the polymer solution was not added to the precursor solution, and the other reaction conditions were compared with those of the same Example 4 . On the other hand, the induction period was found to be the same for 1 hour regardless of the addition of the polymer solution to the precursor solution.

FIG. 11 is a graph comparing hydrogen generation rates according to amounts of polymer solutions added to the precursor solution in the strontium titanate photo-catalyst particles prepared in Example 4 and Examples 6 to 9. As shown in FIG. 10, In addition to the precursor solution of Example 8, the photoactivity of the strontium titanic acid photocatalyst particles obtained by adding 300 mol% of the polymer solution was the largest.

As shown in Table 4 and FIG. 8 to FIG. 11, the strontium titanate photocatalyst particles produced by the spray pyrolysis method according to the present invention had a photoactivity-improved strontium titanate photocatalyst particle of 1 hour (see FIGS. 8 to 11) , And the hydrogen generation rate was at least 600 μmol / h (see Table 4 and FIGS. 8 to 11). In particular, when the polymer solution was added to the precursor solution, the hydrogen generation rate was at least 1,600 μmol / h. As a result, the hydrogen generation rate was increased about 1.6 times by doping the lanthanum element with respect to the control group 2 which is the conventional method (Kang HW et al., International Journal of Hydrogen Energy 2012; 37: 5540-9) The hydrogen generation rate was about 4.1 times higher than that of the control group 2.

Accordingly, the present invention can greatly increase the porosity of the surface of the strontium titanic acid photocatalyst particles by improving the photoactive property using the spray pyrolysis method, so that the photoactivity of the photocatalyst including the hydrogen generation rate can be remarkably increased. Can be usefully used in the production of titanic acid photocatalyst particles.

The present invention has been described with reference to the preferred embodiments. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and equivalents thereof are to be construed as being included in the present invention.

Claims (13)

A first step of preparing a metal precursor solution by dispersing or dissolving a metal precursor material including strontium, titanium, nickel, tantalum and lanthanum elements in a solvent;
A second step of generating droplets using the spraying device of the metal precursor solution prepared in the first step; And
A third step of converting the droplets generated in the second step into strontium titanate particles doped with nickel, tantalum, and lanthanum; Method for producing a strontium titanate photocatalyst particles having improved photoactive properties comprising a. The method of claim 1,
Wherein the metal precursor material of the first step is selected from the group consisting of strontium nitrate (Sr (NO ₃ ) ₂ ), titanium isopropoxide (Ti [OCH (CH ₃ ) ₂ ] ₄ ), nickel nitrate hydrate (Ni (NO ₃ ) ₂ 6H ₂ O ), Tantalum ethoxide (Ta (OC ₂ H ₅ ) ₅ ) and vaginal scattering carbohydrate (La (NO ₃ ) ₃ 6H ₂ O). Way. The method of claim 1,
Wherein the concentration of the metal precursor solution prepared in the first step is 0.1 to 1.0 M, wherein the molar ratio of the nickel to the tantalum is 1: 2. . The method of claim 1,
Wherein the solvent of the metal precursor solution in the first step is a 20% aqueous solution of nitric acid. The method of claim 1,
Wherein the polymer solution is added to the metal precursor solution of the first step, wherein the solution of the strontium titanate photocatalyst is improved. 6. The method of claim 5,
Wherein the polymer solution is a mixture of citric acid and ethylene glycol. The method according to claim 6,
Wherein the molar ratio of citric acid to ethylene glycol is 1: 1. The method of claim 1,
Wherein the droplet generated in the second step is introduced into the atomizer at a flow rate of 0.5 to 50 L / min. The method of claim 1,
Wherein the heat treatment in the third step is performed at 500 to 1500 ° C. The method of claim 1,
The method of manufacturing the strontium titanate photocatalyst particles with improved photoactive characteristics further comprising the step of additionally supporting platinum on the surface of the strontium titanate particles prepared in the third step. The method of claim 10,
The step of supporting the platinum is carried out by adding a water-soluble platinum chloride (H ₂ PtCl ₆ ) solution, stirring the solution, and removing the solvent, thereby improving the photocatalytic activity of the strontium titanate photocatalyst particles. Strontium titanate photocatalyst particles with improved photoactive properties, characterized by the formula SrTiO ₃ : Ni / Ta / La prepared by the process according to any one of claims 1 to 11. 13. The method of claim 12,
The strontium titanate photocatalyst particle improved in photoactivity characteristics, wherein a platinum catalyst is supported on the surface of the photocatalyst particles.

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