JP7101863B2 - Visible light active catalyst powder - Google Patents

Description

Regarding visible light active catalyst powder.

TiO ₂ , which is a typical photocatalytic substance, has excellent durability, abrasion resistance, is a safe and non-toxic substance, and has the advantages of being inexpensive. On the other hand, since it has a large bandgap energy and can absorb only light below ultraviolet rays, it must be used together with a separate ultraviolet supply device or outdoors where ultraviolet rays are abundant, and it is applied indoors or under LEDs. There is a limit to what you can do.

From this aspect, many studies have been carried out on catalysts having photoactivity in visible light capable of absorbing visible light and methods for producing the same for the purpose of indoor application. However, it is difficult to find consistent trends in many research cases, and in particular, it is difficult to find the results of performance verification under actual living conditions.

An embodiment of the present invention provides a visible light active catalyst powder having improved visible light responsiveness and further improved photocatalytic performance.

In one embodiment of the present invention, it is a visible photoactive catalyst powder containing composite particles, wherein the composite particles include platinum particles; tungsten oxide particles; and the tungsten oxide particles carry the platinum particles. Then, the XPS spectrum of Pt with respect to 4f _7/2 measured for the visible light-activated catalyst powder has at least one normal distribution extracted via the Voigt function and extracted via the Voigt function. The other normal distribution is the first normal distribution having the first peak at the coupling energy of 70.8 eV to 71.2 eV, and the integral area of the XPS spectrum with respect to 4f _7/2 of the Pt vs. the integral of the first normal distribution. Provided are visible photoactive catalyst powders having an area ratio of 85% or more.

In one embodiment of the present invention, (a) a step of mixing a tungsten oxide powder with a platinum precursor solution to prepare a slurry solution, and then irradiating the slurry solution with light to proceed with a primary photoreaction; (B) A method for producing a visible light-active catalyst powder, which comprises a step of adding alcohol to the slurry solution and then irradiating with light to advance a secondary light reaction, and measuring the visible light-active catalyst powder. In the XPS spectrum of Pt for 4f _7/2 , at least one normal distribution is extracted via the Voigt function, and one normal distribution extracted via the Voigt function has a coupling energy of 70.8 eV. It is the first normal distribution having the first peak at ~ 71.2 eV, and the ratio of the integrated area of the XPS spectrum to the integrated area of the first normal distribution of Pt 4f _7/2 is 85% or more. A method for producing a catalyst powder is provided.

The visible light active catalyst powder has further improved visible light responsiveness, excellent photocatalytic efficiency, and can ensure economic efficiency in the manufacturing process.

The schematic diagram of the visible light active catalyst particle by one embodiment of this invention. XPS analysis graph for 4f _7/2 of Pt measured for visible light active catalyst powder obtained from Example 1. XPS analysis graph for 4f _7/2 of Pt measured for visible light active catalyst powder obtained from Example 2. XPS analysis graph for 4f _7/2 of Pt measured with respect to the visible light active catalyst powder obtained from Comparative Example 1. XPS analysis graph for 4f _7/2 of Pt measured with respect to the visible light active catalyst powder obtained from Comparative Example 2.

Hereinafter, an embodiment of the present invention will be described in detail. However, this is presented as an example, and this does not limit the present invention, and the present invention is only defined by the scope of the claims described later.

In one embodiment of the present invention, a visible light active catalyst powder containing composite particles is provided. The composite particles include platinum particles; tungsten oxide particles; and the tungsten oxide particles carry the platinum particles.

The visible light active catalyst powder can be formed as an aggregate of the composite particles.

The XPS spectrum of Pt for 4f _7/2 measured for the visible photoactive catalyst powder had at least one normal distribution extracted via the Voigt function and was extracted via the Voigt function. One normal distribution is the first normal distribution having the first peak from 70.8 to 71.2, and the ratio of the integrated area of the XPS spectrum to the integrated area of the first normal distribution with respect to 4f _7/2 of the Pt is It may be 85% or more.

In one embodiment, the XPS spectrum of the Pt with respect to 4f _7/2 may agree with the first normal distribution, in which case the integrated area of the XPS spectrum with respect to 4f _7/2 of the Pt vs. the first normal distribution. The ratio of the integrated area of is 100%.

In one embodiment, the second normal distribution with the second peak at 71.8-72.2 along with the first normal distribution is extracted from the XPS spectrum of Pt for 4f _7/2 via the Voigt function. In this case, the ratio of the integrated area of the XPS spectrum to the integrated area of the first normal distribution to 4f _7/2 of the Pt may be 85% or more and less than 100%.

In addition to the first normal distribution and the second normal distribution, other normal distributions may exist as the normal distribution extracted from the XPS spectrum of Pt for 4f _7/2 via the Voigt function.

For the XPS (X-ray Photoelectron Spectroscopy) spectrum of Pt with respect to 4f _7/2 , an ESCA XPS measuring device manufactured by Sigma Probe can be used.

The first normal distribution and the second normal distribution are obtained by extracting from the XPS spectrum for 4f _7/2 of Pt measured with respect to the visible light active catalyst powder via the Voigt function. For example, it can be obtained so that the R ² value is 0.999 or more by using the Voice spectrum.

The composite particles are formed in a form in which nano-sized platinum particles are supported on the surface of the tungsten oxide particles.

The platinum particles are formed by reduction from the platinum precursor in the case of the production method described later. For example, when the platinum precursor is H ₂ PtCl ₆ , the oxidation number of Pt is +4, and such Pt ⁴⁺ ions are reduced to form platinum particles among the composite particles. Of the composite particles, platinum particles can effectively produce a visible light activating effect because they are reduced to zero oxidation number. Platinum particles having an oxidation number of 0 mean those supported in a non-ionic metallic state.

However, some platinum particles among the composite particles have an oxidation number of +2. Ionic platinum particles such as Pt ²⁺ , which are produced by incomplete reduction of platinum during the manufacturing process, do not work well as a co-catalyst during the photocatalytic reaction of the composite particles, and are rather harmful. It interferes with photocatalytic reactions such as gas removal reactions and reduces overall efficiency. That is, the platinum particles supported in the ionic state interfere with the photocatalytic reaction of the composite particles as a visible light active catalyst, which may cause a deterioration in performance. Further, if the content of platinum particles supported in such an ionic state is increased, it can be said that an expensive platinum precursor is wasted.

FIG. 1 is a cross-sectional view schematically showing a composite particle 10 according to an embodiment of the present invention.

In FIG. 1, the composite particle 10 includes a tungsten oxide particle 1 and a platinum particle 2. For convenience, in FIG. 1, the platinum particles 2 are not shown separately according to the oxidation number, but the platinum particles when the oxidation number is not 0 or the oxidation number is +2 are platinum particles having an oxidation number of 0. Mixed with.

In the composite particles 10, electrons and holes generated from energy obtained by absorbing light generate surface active oxygen such as superoxide anion or hydroxy group, thereby purifying air, deodorizing, and antibacterial action. It is a substance that can be used. For example, the superoxide anion or hydroxy group generated by the photoactive action of the composite particles can decompose harmful substances such as acetaldehyde, ammonia, formaldehyde, acetic acid, TVOC, etc. Antibacterial action against bacteria such as is possible.

The composite particles 10 can be activated not only by ultraviolet rays but also by visible light, and can exhibit excellent efficiency even with an indoor light source, so that a separate ultraviolet supply device may not be required.

Since the composite particles have a high content of platinum particles having an oxidation number of 0 in the entire platinum particles, they have an excellent visible light activating effect. Therefore, the visible light active catalyst powder can improve the economic efficiency in the manufacturing process and reduce the waste of the precursor.

On the other hand, the composite particles may have an advantage that the photocatalytic performance is improved as the content of the platinum particles having an oxidation number of 0 increases, and the complete decomposition rate of the reaction intermediate is increased at the time of decomposition of harmful gas. That is, when the harmful gas is decomposed by the visible light active catalyst powder, the probability that the reaction intermediate is completely decomposed into water and CO ₂ increases.

The XPS spectrum of Pt with respect to 4f _7/2 is measured with respect to the binding energy of the electrons belonging to the 4f electron shell of the platinum particles contained in the visible photoactive catalyst powder. .. The first normal distribution has a binding energy of 70.8 eV to 71.2 eV, and specifically has a peak at around 71.0 eV. Therefore, the second normal distribution is related to platinum particles having an oxidation number of 0. Refers to platinum particles having an oxidation number of +2 because they have a binding energy of 71.8 eV to 72.2 eV and specifically have a second peak at around 72.0 eV.

That is, the XPS spectrum of Pt with respect to 4f _7/2 is shown to include not only platinum particles having an oxidation number of 0 but also platinum particles having other oxidation numbers. By extracting with the second normal distribution, the content ratio of the platinum particles having an oxidation number of 0 and the platinum particles having an oxidation number of +2 can be found.

By comparing the integrated area of the first normal distribution and the integrated area of the second normal distribution, the mass ratio of the platinum particles having an oxidation number of 0 and the platinum particles having an oxidation number of +2 can be obtained. In the visible light active catalyst powder, the ratio of the integrated area of the first normal distribution to the total of the integrated area of the first normal distribution and the integrated area of the second normal distribution is 85% or more, specifically 90. It can be% to 100%.

The platinum particles in the visible photoactive catalyst powder are formed of platinum particles having most oxidation numbers of 0, and the XPS spectrum of Pt with respect to 4f _7/2 can itself have the first normal distribution. In this case, the ratio of the integrated area of the XPS spectrum to the integrated area of the first normal distribution with respect to 4f _7/2 of the Pt is 100% (see the case of Example 1 described later).

The normal distribution extracted from the XPS spectrum of Pt for 4f _7/2 via the Voigt function includes the normal distribution for platinum having other oxidation numbers in addition to the first normal distribution and the second normal distribution. The distribution can be further extracted. However, the higher the content of the platinum particles having an oxidation number of 0, the better the photocatalytic performance. Therefore, it is preferable that there is no normal distribution for platinum particles having another oxidation number or the integrated area is relatively small.

The first normal distribution and the second normal distribution have R ² values of 0.999 or more, and are excellent in the accuracy of normal distribution fitting.

The tungsten oxide particles 1 can be formed of spherical, plate-shaped or needle-shaped particles as a carrier by, for example, a sol-gel method or a hydrothermal synthesis method, but the shape is not limited. ..

The tungsten oxide particles 1 are excellent in visible light activity performance.

The platinum particles 2 can be supported on the porous metal oxide by a photo-evaporation method, but the platinum particles 2 are not limited thereto.

The platinum particles 2 act as a co-catalyst, facilitating the separation of electrons and holes from the energy obtained by absorbing light.

The average diameter of the tungsten oxide particles 1 used in the production of the composite particles 10 can be calculated by electron microscopy such as SEM image analysis, for example, the average diameter is from about 30 nanometers (nm) to about 500. Those that are nanometers (nm) can be used. If the average diameter of the tungsten oxide particles 1 is too large beyond the above range, it is impossible to form a stable coating liquid when the visible photoactive catalyst powder is dispersed in a solvent, and the visible When manufacturing a filter using the photoactive catalyst powder, it may be inconvenient for the step of coating the visible photoactive catalyst powder. If the diameter of the tungsten oxide particles 1 is less than the above range and is too small, the platinum particles 2 may not be stably supported.

The average particle size of the composite particles 10 is about 1 micrometer (μm) or less, and specifically, it may be about 0.2 micrometer to about 1 micrometer, for example, about. It may be 0.4 micrometer to about 0.5 micrometer. The average particle size of the composite particles 10 is obtained from a measurement with a particle size analyzer (Beckman, LS 13 320) with respect to an approximately 4 wt% aqueous dispersion of a visible photoactive catalyst. Further, the maximum particle size of the visible light active catalyst particles 10 is set to be about 10 micrometers or less.

The visible photoactive catalyst particles 10 may contain 100 parts by weight of the tungsten oxide particles 1 and about 0.01 to about 5 parts by weight of the platinum particles 2. By adjusting these contents with a weight ratio within the above range, the tungsten oxide particles 1 sufficiently generate electrons and holes by visible light, and the platinum particles 2 generate electrons and holes. It is possible to sufficiently prevent recombination and effectively improve the photocatalytic activity efficiency.

When the content of the tungsten oxide particles 1 exceeds the content range, electrons and holes generated by visible light can be easily recombined, and their separation is difficult, and the photocatalytic activity is sufficiently exhibited. If the content is less than the above range, the number of electrons transferred from the tungsten oxide particles 1 may not be sufficiently secured, and the photocatalytic activity may decrease. The exposed area to the photocatalyst may be reduced and the photocatalytic performance may be reduced.

The specific surface area of the tungsten oxide particles 1 may be about 50 m ² / g to about 500 m ² / g. By having a high level specific surface area within the above range, it can be effectively exposed to a light source such as visible light, and the porosity is formed to a suitable level to sufficiently support the platinum particles 2. be able to.

Hereinafter, a method for producing a visible light-activated catalyst powder according to one embodiment of the present invention will be specifically described.

The method for producing the visible light active catalyst powder can be carried out by sequentially performing the following steps (a) to (c).

(A) Tungsten oxide powder is mixed with a platinum precursor solution to prepare a slurry solution, and then the slurry solution is irradiated with light to proceed with a primary photoreaction.

(B) After adding alcohol to the slurry solution, light irradiation is performed to promote a secondary photoreaction.

In the step (a) above, the tungsten oxide powder is prepared by pulverizing it to a level of micro units or less in order to maximize the reaction area.

As the platinum precursor compound for producing the platinum precursor solution, a substance that can be reduced to platinum by electrons excited by light irradiation can be used, and a salt compound dissolved in an aqueous solution can be used without limitation. Specifically, PtCl ₂ , PtCl ₄ , PtBr ₂ , H ₂ PtCl ₆ , K ₂ (PtCl ₄ ), Pt (NH ₃ ) ₄ Cl ₂ , Pt (NH ₃ ) ₄ (OH) ₂ , Pt (NH ₃ ). ) ₄ (NO ₃ ) ₂ , Pt (NH ₃ ) ₂ (NO ₂ ) ₂ , H ₂ Pt (OH) ₆ , Na ₂ Pt (OH) ₆ , K ₂ Pt (OH) ₆ and the like.

For example, the concentration of the platinum precursor solution is adjusted by the relative content with respect to the tungsten oxide powder so that the content of platinum to 100 parts by weight of the tungsten oxide particles is about 0.01 part by weight to about 5 parts by weight. Can be done.

During the primary photoreaction in step (a), platinum ions separated from the platinum precursor adhere to the surface of the tungsten oxide particles, and during the secondary photochemical reaction in step (b), the tungsten oxidation occurs. It is understood that the reduction reaction of platinum ions adhering to the surface of the object particles mainly occurs.

In order to show the XPS analysis result for 4f _7/2 of Pt described above, the finally obtained visible photoactive catalyst powder was completely reduced to an oxidation number of 0 as compared with the platinum particles having an oxidation number. It must be formed so that the proportion of platinum particles is even higher.

Therefore, by adjusting various process conditions, the above-mentioned visible light active catalyst powder of the present invention can be obtained. Hereinafter, specific process conditions capable of synthesizing the above-mentioned visible light-activated catalyst powder of the present invention will be described as an example.

First, the ratio between the time for advancing the primary photochemical reaction (primary photochemical reaction time) and the time for advancing the secondary photochemical reaction (secondary photochemical reaction time) can be adjusted.

Since the secondary photoreaction proceeds at a very high speed, it is understood that the final formation ratio of platinum particles having an oxidation number of 0 is not significantly affected. On the contrary, platinum ions are generated during the primary photoreaction. Evenly and firmly adhering to the surface of the tungsten oxide particles affects the final formation ratio of the platinum particles having an oxidation number of 0.

Therefore, it is important to allow the primary photochemical reaction to proceed sufficiently for a sufficient period of time so that the reaction can proceed sufficiently.

For example, the primary photoreaction can be carried out for 4 to 24 hours.

For example, the secondary photoreaction can be carried out for 2 to 6 hours.

In one embodiment, the primary photoreaction time is longer than the secondary photoreaction time, specifically, the ratio of the primary photoreaction time to the secondary photochemical reaction time is 2: 1 to 12: 1. May be.

Further, it is important to sufficiently stir the slurry solution when performing each of the photoreactions of the step (a) and the step (b) by the light irradiation.

For example, an inert gas such as nitrogen can be injected into the slurry solution so that the slurry solution is agitated while the photoreaction proceeds.

The injection flow rate, injection method and position of the inert gas can help the photochemical reaction to proceed well. For example, the flow rate of the inert gas injected into the slurry solution may be 5 L / min to 30 L / min.

In one embodiment, nitrogen can be used as the inert gas. If the slurry solution is agitated by utilizing nitrogen gas, the agitation efficiency is superior to that of mechanical agitation, and there is an advantage that a secondary effect of removing oxygen in the slurry solution can be obtained.

In the step (a), when the slurry solution is prepared, the concentration of the tungsten oxide powder can be set to 1 to 10 wt%.

In the step (b), the addition ratio of the alcohol can be 1 to 30 wt% of the slurry solution.

By way of example, the viscosity of the slurry solution may be from about 5.0 cP to about 8.0 cP at 25 ° C. The viscosity of the slurry solution can be measured using a Brookfield viscometer (Spindle No.: 61, speed: 200 rpm, measurement time: 30 seconds).

For example, at the time of the primary light reaction, the intensity of the light irradiation may be about 5,000 lux to about 100,000 lux, and at the time of the secondary light reaction, the intensity of the light irradiation is the light of the primary light reaction. It can be higher than the intensity of irradiation. Specifically, the intensity of the secondary light irradiation may be 1 to 10 times, specifically 3 to 5 times higher than the intensity of the primary light irradiation.

After the secondary light irradiation, the catalyst is selectively recovered and dried by centrifugation or the like.

Hereinafter, examples and comparative examples of the present invention will be described. Such the following examples are merely one embodiment of the present invention, and the present invention is not limited to the following examples.

(Example)
Example 1
A solution in which 7 wt% of tungsten oxide powder was dispersed in 93 wt% of water was produced. A supporting raw material which is a 10 wt% aqueous solution of platinum chloride acid (H ₂ PtCl ₆ ) is mixed with a tungsten oxide powder dispersion solution having an average particle size of 1 μm, and the platinum content is 1 part by weight with respect to 100 parts by weight of the tungsten oxide powder. The slurry solution was produced as described above.

The viscosity of the slurry solution measured using a Brookfield viscometer (Spindle No .: No. 61, speed: 200 rpm, measurement time: 30 seconds) was 6.2 cP at 25 ° C.

Next, the slurry solution is put into a photoreactor, the gas generator is installed so as to be connected to the photoreactor, and then the gas generator is continuously irradiated with the primary light and the secondary light. The nitrogen generated from the above was directly injected into the inside of the slurry solution so that the slurry solution was agitated by the nitrogen. The purity of the added nitrogen was 98.00%, and the flow rate was 10 L / min.

Using a visible light irradiation device, the slurry solution in the photoreactor was irradiated with visible light energy of 400 nm to 700 nm, and the primary light reaction was carried out for 6 hours. Next, the visible light irradiation was cut off for about 2 minutes, and the particles were added so that the proportion of methanol was 5 wt% in the slurry solution, and then the visible light energy was applied using the same irradiation device as the primary light reaction. By irradiating the slurry solution in the photoreactor for 2 hours and performing a secondary photoreaction, platinum particles were supported on tungsten oxide particles to produce a visible light active photocatalyst powder.

Example 2
A visible light active photocatalyst powder was produced by the same method as in Example 1 except that the primary photoreaction was carried out for 4 hours and the secondary light reaction was carried out for 2 hours.

Comparative Example 1
A visible light active photocatalyst powder was produced by the same method as in Example 1 except that the primary photoreaction was carried out for 2 hours and the secondary light reaction was carried out for 3 hours.

Comparative Example 2
The primary photoreaction was carried out for 4 hours and the secondary light reaction was carried out for 2 hours, and nitrogen was not directly injected into the slurry solution but was poured onto the upper part of the slurry solution in the photoreactor to mechanically charge the slurry solution. A visible light active photocatalyst powder was produced, except that it was stirred in.

Evaluation Experimental Example 1: XPS analysis The visible photoactive catalyst powders obtained from Example 1 and Comparative Examples 1 and 2 were subjected to Pt 4f _7/2 using X-ray Photoelectron Spectroscopy (ESCA of Sigma Probe). The XPS spectrum for was obtained. The XPS spectrum of the obtained Pt with respect to 4f _7/2 was fitted by Voigt augment to extract a normal distribution.

FIG. 2 is the result of Example 1, where curve A is an XPS spectrum of Pt for 4f _7/2 , and curve B corresponds to a first normal distribution with a peak at about 70.9. The R ² of the extracted normal distribution in FIG. 2 is 0.99997. In FIG. 2, the curve A and the curve B substantially coincide with each other.

FIG. 3 is the result of Experimental Example 2, in which the curve A is the XPS spectrum of Pt with respect to 4f _7/2 , and the curve B corresponds to the first normal distribution having a peak at about 70.9. C corresponds to a second normal distribution with a peak at about 72.0. The R ² of the extracted normal distribution in FIG. 3 is 0.99993.

FIG. 4 is the result of Comparative Example 1, in which the curve A is the XPS spectrum of Pt with respect to 4f _7/2 , and the curve B corresponds to the first normal distribution having a peak at about 70.9. C corresponds to a second normal distribution with a peak at about 72.0. The R ² of the extracted normal distribution in FIG. 4 is 0.99991.

FIG. 5 shows the result of Comparative Example 2, in which the curve A is the XPS spectrum of Pt with respect to 4f _7/2 , and the curve B corresponds to the first normal distribution having a peak at about 70.9. C corresponds to a second normal distribution with a peak at about 72.0. The R ² of the extracted normal distribution in FIG. 5 is 0.99994.

In FIGS. 2 to 5, the ratio of the integrated area of the XPS spectrum to the integrated area of the first normal distribution with respect to 4f _7/2 of Pt was calculated and shown in Table 1 below.

Experimental Example 2
The performance evaluation of the visible light active catalyst powder produced in Example 1-2 and Comparative Example 1-2 was performed by the gas bag evaluation described below.

A container containing 0.5 g of visible light active catalyst powder was placed in a gas bag and sealed, the remaining gas was removed, and 3 L of acetaldehyde 3 ppm gas was injected. The illuminance of the light source was 25,000 lux. The gas before injection and the gas 30 minutes after injection are collected in a DNPH (2,4-dinitrophenylhydrazine, 2,4-dinitrophenylhydrazine) cartridge and subjected to high performance liquid chromatography (HPLC). ), The acetaldehyde concentration was analyzed, and the acetaldehyde removal performance for each sample was calculated.

The evaluation results are shown in Table 2 below.

Although the preferred embodiments of the present invention have been described in detail above, the scope of rights of the present invention is not limited to this, and various persons skilled in the art using the basic concept of the present invention defined in the following claims. Modifications and improvements are also within the scope of the present invention.

1 Tungsten oxide particles 2 Platinum particles 10 Composite particles

Claims (8)

Visible light active catalyst powder containing composite particles.
The composite particles include platinum particles; tungsten oxide particles; and
The tungsten oxide particles carry the platinum particles and
The XPS spectrum of Pt for 4f _7/2 measured for the visible photoactive catalyst powder had at least one normal distribution extracted via the Voigt function and was extracted via the Voigt function. One normal distribution is the first normal distribution having the first peak at a coupling energy of 70.8 eV to 71.2 eV.
The ratio of the integrated area of the XPS spectrum to the integrated area of the first normal distribution with respect to 4f _7/2 of the Pt is 85% or more .
When the normal distribution is extracted via the Voigt function, the R ² value is 0.999 or more.
Visible light active catalyst powder. The XPS spectrum of Pt with respect to 4f _7/2 agrees with or has the first normal distribution.
Along with the first normal distribution, a second normal distribution having a second peak with a binding energy of 71.8 eV to 72.2 eV is extracted from the XPS spectrum for 4f _7/2 of the Pt via the Voigt function.
The visible light active catalyst powder according to claim 1. The diameter of the composite particle is 1 micrometer or less.
The visible light active catalyst powder according to claim 1. The diameter of the platinum particles is 1 nanometer to 10 nanometer.
The visible light active catalyst powder according to claim 1. The content of the platinum particles is 0.01 parts by weight to 5 parts by weight with respect to 100 parts by weight of the tungsten oxide particles .
The visible light active catalyst powder according to claim 1. (A) A step of mixing a tungsten oxide powder with a platinum precursor solution to prepare a slurry solution, and then irradiating the slurry solution with light to proceed with a primary photoreaction;
(B) A step of adding alcohol to the slurry solution and then irradiating with light to promote a secondary photoreaction is included.
A method for producing visible light-activated catalyst powder.
The XPS spectrum of Pt for 4f _7/2 measured for the visible photoactive catalyst powder had at least one normal distribution extracted via the Voigt function and was extracted via the Voigt function. One normal distribution is the first normal distribution having the first peak at the coupling energy of 70.8 eV to 71.2 eV, and the integrated area of the XPS spectrum with respect to 4f _7/2 of the Pt vs. the integrated area of the first normal distribution. The ratio is 85% or more ,
At the time of normal distribution extraction via the Voigt function, the R ² value is 0.999 or more.
The ratio of the time for advancing the primary photochemical reaction to the time for advancing the secondary photochemical reaction is 2: 1 to 12: 1.
A method for producing a visible light active catalyst powder. The primary photoreaction is carried out for 4 to 24 hours.
The method for producing a visible light active catalyst powder according to claim 6 . The primary photoreaction and the secondary photochemical reaction are carried out by injecting an inert gas into the slurry solution and stirring the mixture.
The method for producing a visible light active catalyst powder according to claim 6 .

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