KR101541746B1 - Photocatalytic hydrogen production from water under visible light and hydrogen production from water using it - Google Patents

Abstract

The present invention relates to a photocatalyst and a method for generating hydrogen through water decomposition using visible light. More specifically, a SnP_6+/Nf/Pt-TiO_2 photocatalyst for generating hydrogen through water decomposition using visible light includes TiO_2 in which platinum is loaded, and a Nafion layer formed on the surface of the TiO_2, wherein SnP_6+ is impregnated in the the Nafion layer. The present invention can improve an activity of the TiO_2 in the visible light without dissolving dyes in a solution to efficiently generate hydrogen gas through water decomposition using visible light.

Description

[0001] The present invention relates to a photocatalytic hydrogen production process,

The present invention relates to a photocatalyst for the production of visible light water-decomposable hydrogen and a method for producing visible hydrogen-decomposing hydrogen using the same, and more particularly, to a method for producing visible light by decomposition of platinum-loaded TiO ₂ and a Nafion layer formed on the surface of TiO ₂ , Layer is SnP ⁶⁺ -doped SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst for visible light water decomposition hydrogen production, and a method for producing visible hydrogen decomposition hydrogen using the same.

Photocatalysis refers to a substance that catalyzes a chemical reaction by a variety of light sources, including sunlight. Photosynthesis occurring in the chlorophyll of a plant is a representative photocatalysis system. Photocatalyst system is decomposed with water to decompose water to produce oxygen and hydrogen (water splitting), CO ₂ reduction method that produces methanol and methane by using CO ₂ (CO ₂ reduction), photolysis for decomposing the harmful organic matters in the human body (photo degradation).

This photocatalytic system is a system that exerts its own action by using only sunlight without obtaining energy from the outside. Since the photocatalyst used here is harmless to the human body and can be reused under specific conditions, it can be considered as a next generation clean energy source.

In particular, water decomposition produces hydrogen gas by decomposing water by the following equation.

_{H 2 O → 1 / 2O 2} + H 2 (△ G = 237KJ / mol)

Water decomposition requires a photocatalyst that absorbs sunlight, causing electrons to exude from the valence band to the conduction band. The photocatalyst should be hydrophilic because it is inexpensive, harmless to the human body, excellent in stability, and often reacts directly with water.

The standard Gibbs free energy change Δ G ° value of the water decomposition reaction is 237 kJ / mol and the band gap energy is 1.23 eV. TiO ₂ is mainly used as a photocatalyst because it satisfies these conditions. However, the band gap energy of TiO ₂ was 3.0 eV, which was not suitable for using visible light.

When the electrons are excited, the recombination occurs in which the excited electrons are recombined with the holes. If this phenomenon occurs, the efficiency of hydrogen generation is decreased. Therefore, in order to prevent this, a cocatalyst acting as an election trap is coated on the catalyst surface. As the cocatalyst, noble metals such as Pt, Au, Ag and Pd are mainly used. In recent years, transition metal oxides such as RuO ₂ and NiO and non-metal oxides such as MOS ₂ have been studied to replace expensive noble metals. In addition, EDTA and methanol are used as sacrificial reagents to continuously transfer electrons to the catalyst.

On the other hand, sunlight has light of ultraviolet rays (300 to 400 nm), visible light (400 to 700 nm) and near infrared rays (700 to 2500 nm), and visible light accounts for about 43% do.

In the case of TiO ₂ , which is mainly used as a photocatalyst, only about 5% of the sunlight irradiated on the ground surface is used because it absorbs light of 400 nm or less. In order to solve the above problems, a dye-sensitized photocatalysis using a visible light dye has been developed.

The dye-sensitized photocatalyst absorbs visible light, not the catalyst, and the excited electrons in the dye move to the catalyst, allowing the use of visible light. As the representative visible light dyes, ruthenium-based dyes are widely used. However, in the case of the ruthenium dye, the efficiency in the visible light region is excellent, but it is expensive and environmentally unstable.

Therefore, various visible light dyes for replacing ruthenium have been actively studied, and tin porphyrin, which is a relatively inexpensive metal, has a band gap energy of 1.97 eV, similar to ruthenium dyes, Stability, and exhibits a wide range of light absorption in visible light, and is widely used as a visible light dye.

Korean Patent Laid-Open No. 10-2012-0008341

In order to solve the problems of the prior art as described above, the present invention relates to a method for improving the activity of TiO ₂ in visible light and using SnP ⁶⁺ / Nf / Pt-TiO ₂ capable of efficiently producing hydrogen gas through water decomposition using visible light And a method of producing hydrogen by using the same.

The present invention also relates to a SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst for visible light water-decomposable hydrogen production which can be used independently without dissolving the dye in a solution by integrating the dye and the catalyst through a simple process, And to provide a method for generating the same.

Another object of the present invention is to provide a SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst for producing visible visible light water-decomposable hydrogen, which can generate hydrogen in the entire pH range, and a method for producing water-decomposed hydrogen using the same.

In order to achieve the above object, the present invention is TiO ₂ The platinum loading; And a Nafion layer formed on the surface of the TiO ₂ , wherein the Nafion layer is impregnated with SnP ⁶⁺ , wherein the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst .

The platinum is TiO _2, and the total loading of 1 to 10% by weight, based on the weight, Nafion layer formed on the TiO ₂ surface of the platinum loading is preferably formed to a thickness of 1 ~ 20㎚.

The SnP ⁶⁺ is preferably contained in an amount of 0.1 to 10% by weight based on the total weight of the photocatalyst.

Further steps of the invention is producing a (S1) of the visible light dyes _{[Sn (OH 2) 2 TPy} H P (4)] 6+ (SnP 6+); (S2) preparing Nf / Pt-TiO ₂ having a nafion layer formed on the surface of platinum loaded TiO ₂ ; And (S3) the Nf / Pt-TiO ₂ by combining the SnP ^{6+ 6+} SnP / Nf / Pt-TiO ₂ photocatalyst preparing a; SnP characteristics for visible light to decompose the hydrogen water produced by including ⁶⁺ / A method for producing a Nf / Pt-TiO ₂ photocatalyst is provided.

The visible light dyes of step (S1) may be prepared by reacting (a) pyrrole and 4-pyridinecarboxaldehyde with 5,10,15,20-tetrakis (4-pyridyl) Porphyrin (H ₂ TPYP (4)); (b) dissolving the 5,10,15,20-tetrakis (4-pyridyl) porphyrin in a solvent (pyridine), adding tin (II) chloride dihydrate and reacting Synthesizing trans-dichloro [5,10,15,20-tetrakis (4-pyridyl) porphyrin] tin (IV) (SnCl ₂ TPyP (4)); (c) adding potassium carbonate (K ₂ CO ₃ ) to the trans-dichloro [5,10,15,20-tetrakis (4-pyridyl) porphyrin] (IV) (Sn (OH) ₂ TPyP (4)) as a starting material; And (d) the trans-dihydroxy rokso [5,10,15,20-tetrakis (4-pyridyl) porphyrin] by acid treatment in the tin (Ⅳ) [Sn (OH _{2) 2} ^H TPy P (4) ] ^{6 +} (SnP ⁶⁺ ).

The (S2) Nf / Pt-TiO 2 of the step is preferably platinum (Pt) to the TiO ₂ surface is loaded with 1-10% by weight relative to the total weight of TiO _2.

The Nf / Pt-TiO ₂ of the step (S2) is preferably formed such that the Nafion layer is formed on the surface of the TiO ₂ loaded with platinum in an amount of 10 to 35% by weight based on the total weight of TiO ₂ .

The SnP ⁶⁺ in the step (S3) is preferably contained in an amount of 0.1 to 10% by weight based on the total weight of the Nf / Pt-TiO ₂ photocatalyst.

Further, the present invention provides a composition for producing hydrogen peroxide decomposing visible light comprising SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst and water.

The SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst is preferably contained in an amount of 1 to 5 g / L based on 1.0 g / L of water.

The present invention also provides a visible light water decomposition hydrogen production method comprising the step of supplying gas to a composition for visible light hydrogen production and then irradiating light.

The photocatalyst for visible light hydrogen production according to the present invention improves the activity of TiO ₂ in visible light so that hydrogen gas can be efficiently produced through water decomposition using visible light and the dye and the catalyst are integrated through a simple process, It can be used independently without dissolving in a solution, and it is possible to generate hydrogen in the entire pH range, thereby further improving the hydrogen production efficiency.

1 is a graph showing the results of ¹ H NMR spectroscopic analysis of 5,10,15,20-tetrakis (4-pyridyl) porphyrin produced in the process of producing a visible light dye according to the present invention.
2 is a graph showing the results of ¹ H NMR spectroscopic analysis of trans-dichloro [5,10,15,20-tetrakis (4-pyridyl) porphyrin] tin (IV) produced in the process of producing a visible light dye according to the present invention to be.
3 shows the results of ¹ H NMR spectroscopic analysis of trans-dihydroxy [5,10,15,20-tetrakis (4-pyridyl) porphyrin] tin (IV) produced in the process of producing a visible light dye according to the present invention Fig.
4 is a graph showing the results of ¹ H NMR spectroscopic analysis of [Sn (OH ₂ ) ₂ TPy ^H P (4)] ^{6+ which} is a visible light dye prepared according to the present invention.
FIG. 5 is a graph showing the results of UV-vis spectrum and [Sn (OH ₂ ) ₂ TPy ^H P (4)] ⁶⁺ powder as a visible light dye prepared according to the present invention.
FIG. 6 is a graph showing TEM and TEM-EDS measurement results of platinum-loaded Pt-TiO _{2 in} the process of preparing Nf / Pt-TiO ₂ catalyst according to the present invention. 6A is a TEM, 6b is an EDS, and 6c is an S-TEM image.
FIG. 7 is a TEM and TEM-EDS measurement result of Nf / Pt-TiO ₂ prepared according to the present invention. 7A is a TEM, and 7b is an EDS image.
8 is a graph showing XPS spectral results of Nf / Pt-TiO ₂ prepared according to the present invention.
9 is a graph showing FT-IR analysis results of Nf / Pt-TiO ₂ prepared according to the present invention.
10 is a graph showing the results of UV-vis spectroscopy of the absorption of SnP ⁶⁺ , which is a visible light dye, when preparing SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst according to the present invention.
FIG. 11 is a graph showing the sorption band of SnP ⁶⁺ , which is a visible light dye, in the manufacture of SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst according to the present invention.
12 is a graph showing the results of measurement of the reflectance of the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared according to the present invention.
13 is a graph showing the TGA analysis results of the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared according to the present invention.
14 is a TEM-EDS measurement result of the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared according to the present invention.
FIG. 15 is a graph showing the degree of hydrogen production according to the amount of dye in the water decomposition reaction using the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared according to the present invention.
16 is a graph showing the degree of hydrogen production according to the amount of catalyst in the water decomposition reaction using the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared according to the present invention.
17 is a graph showing the stability of the catalyst (hydrogen generation point) measured in the water decomposition reaction using the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared according to the present invention.
18 is a graph showing the degree of hydrogen production in a water decomposition reaction at pH 9 using SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared according to the present invention.
19 is a graph showing changes in porphyrin dye according to pH change during water decomposition reaction using SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared according to the present invention.
FIG. 20 is a graph showing the change of porphyrin dye according to the pH change in the water decomposition reaction using the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared according to the present invention with the UV-vis spectrum.
21 is a graph showing the degree of hydrogen production according to pH change during the water decomposition reaction using the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared according to the present invention.

Hereinafter, the present invention will be described in detail.

The present inventors to address the active and low surface polarity problem of the visible light is TiO ₂ having, using a tin porphyrin, a visible dye, strong on TiO ₂ surface (-) After a coating of Nafion with a polarity of TiO ₂ It is confirmed that tin porphyrin adheres well by increasing the surface polarity, and hydrogen production can be performed with high efficiency under visible light, and the present invention has been completed on the basis thereof.

The SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst for producing visible visible light decomposition hydrogen includes platinum-loaded TiO ₂ and a Nafion layer formed on the surface of the TiO ₂ , wherein the Nafion layer contains SnP ⁶⁺ Is impregnated.

The TiO ₂ preferably has a diameter of 10 to 100 nm. If the size is less than 10 nm, the efficiency is low, but it is difficult to manufacture, the price is high and the efficiency is low. If the size is more than 100 nm, the area inside TiO ₂ is large, Can happen.

There is platinum is loaded on the surface of the TiO _2, wherein the content of platinum loaded on the TiO ₂ is the total of TiO ₂ is preferably from 1 to 10% by weight relative to the weight, more preferably 5% by weight. When the content is less than 1% by weight, the amount of cocatalyst in which hydrogen is produced is insufficient and hydrogen generation may be small. When the content exceeds 10% by weight, platinum-loaded TiO ₂ becomes too black, The surface area of the catalyst is reduced and hydrogen generation can be reduced because the position of receiving light is small.

A nafion layer is formed on the surface of the platinum-loaded TiO ₂ . The Nafion layer is preferably formed to a thickness of 1 to 20 nm on the surface of the TiO ₂ loaded with platinum. When the thickness is less than 1 nm, it may not be completely cured on the surface, and when it exceeds 20 nm, light may not reach the surface.

It is preferable that SnP ^{6+, which} is a visible light dye absorbed in the Nafion layer, is contained in an amount of 0.1 to 10% by weight based on the total weight of the photocatalyst. When the content is less than 0.1% by weight, the amount of the dye used for photoactivity is not sufficient and the reaction may not be exhibited. When the content exceeds 10% by weight, the color of the solution becomes too dark, Can fall.

^{SnP 6+ / Nf / Pt-TiO} 2 photocatalyst as described above to prepare the (S1) of the visible light dyes _{[Sn (OH 2) 2 TPy} H P (4)] 6+ (SnP 6+), (S2) Pt-TiO ₂ having a Nafion layer formed on the platinum-loaded TiO ₂ surface; and (S3) combining SnP ⁶⁺ and Nf / Pt-TiO ₂ to form SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst.

Hereinafter, the manufacturing method of the present invention will be described in detail in each step.

(S1) [Sn (OH ₂ ) ₂ TPy ^H P (4)] ⁶⁺  Produce

In the present invention, visible light dyes capable of absorbing light in the visible light region are prepared, and visible light of a wider range than that of ultraviolet light is used for decomposition of water using TiO ₂ , and tin By synthesizing the porphyrin dye [Sn (OH ₂ ) ₂ TPy ^H P (4)] ^{6 +,} the cost aspect of Ru ( ^bby ) ³²⁺ with ruthenium, which was mainly used as visible light dye, and the environmentally harmful problem were compensated .

[Sn (OH ₂ ) ₂ TPy ^H P (4)] ⁶⁺ can be prepared as shown in Reaction Scheme 1 below.

[Reaction Scheme 1]

(a) Production of 5,10,15,20-tetrakis (4-pyridyl) porphyrin

First, purified pyrrole and 4-pyridinecarboxaldehyde are dissolved in propionic acid as a solvent and heated at 120 to 160 ° C for 1 to 3 hours, preferably at 140 ° C for 2 Lt; / RTI > Then, the solvent was removed from the reaction solution, and the reaction mixture was immersed in dimethylformamide (DMF) for one day. Column chromatography was performed to obtain purple 5,10,15,20-tetrakis (4-pyridyl) porphyrin 5,10,15, Tetrakis (4-pyridyl) porphyrin (hereinafter referred to as 'H ₂ TPyP (4)') can be obtained.

The pyrrole and 4-pyridinecarboxaldehyde are preferably reacted at a weight ratio of 1 to 2: 1 to 2, more preferably 1: 1. When the reaction ratio is out of the above range, the remaining pyrrole and 4-pyridinecarboxaldehyde react with each other, so that a substance other than the desired substance can be synthesized.

(b) Preparation of trans-dichloro [5,10,15,20-tetrakis (4-pyridyl) porphyrin] tin (IV)

Then, the prepared H ₂ TPyP (4) was dissolved in pyridine as a solvent, tin (II) chloride dihydrate (SnCl ₂ ) was added, and the mixture was stirred at 100 to 140 ° C. for 8 to 12 hours, Preferably at 120 DEG C for 10 hours. The reaction product was filtered using celite and then recrystallized from dichloromethane and n-hexane to obtain a purple crystal of trans-dichloro [5,10,15,20-tetrakis (4-pyridyl) porphyrin] (IV) ( trans- dichloro [5,10,15,20-tetrakis (4-pyridyl) porphyrin] tin (IV), hereinafter referred to as SnCl ₂ TPyP (4)).

The H ₂ TPyP (4) and the tin (II) chloride hydrate are preferably reacted at a weight ratio of 1: 1 to 1: 5, more preferably 1: 2. When the reaction ratio is out of the above range, the reaction may be divided into porphyrin in which tin is located and porphyrin in which tin is not located.

(c) Preparation of trans-dihydroxy [5,10,15,20-tetrakis (4-pyridyl) porphyrin] tin (IV)

The prepared SnCl ₂ TPyP (4) is dissolved in tetrahydrofuran (THF), potassium carbonate (K ₂ CO ₃ ) dissolved in distilled water is added to the solution, and the solution is stirred at 70 to 90 ° C. for 3 to 5 hours, And the mixture is refluxed at 80 DEG C for 4 hours to react. In the reaction, the purple crystal trans-dihydroxy [5,10,15,20-tetrakis (4-pyridyl) porphyrin] tin (IV) synthesized by the completion of the SnCl ₂ TPyP (4) reaction dissolved in tetrahydrofuran ) (trans -dihydroxo [5,10,15,20-tetrakis (4-pyridyl) porphyrin] can be obtained tin (ⅳ), hereinafter referred to _{as, 'Sn (OH) 2 TPyP} (4)' hereinafter).

The SnCl ₂ TPyP (4) and the potassium carbonate are preferably reacted at a weight ratio of 1: 1 to 2: 5, more preferably 1: 2. If the reaction ratio is out of the above range, potassium carbonate remaining after the synthesis may reduce the purity of porphyrin.

(d) Preparation of [Sn (OH ₂ ) ₂ TPy ^H P (4)] ⁶⁺

In the case of the synthesized Sn (OH) ₂ TPyP (4), it can not be used in the water decomposition process since it is not soluble in water. Therefore, the Sn (OH) ₂ TPyP (4) is subjected to an acid treatment to replace the Sn (OH) ₂ TPyP (4) with a +6 polarity to make it soluble in water. That is, for the acid treatment, the acid solution was dissolved in Sn (OH) ₂ TPyP (4), layered using acetone, and left for 3 days to obtain a purple crystalline [Sn (OH ₂ ) ₂ TPy ^H P (4)] ⁶⁺ (hereinafter referred to as "SnP ⁶⁺ ").

As the acid solution for the acid treatment, an aqueous solution such as nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid and the like may be used. In particular, 1% nitric acid aqueous solution is preferably used.

(S2) Nf / Pt-TiO ₂  Produce

TiO ₂ , which is the most used catalyst for water decomposition, has a problem of low efficiency because it uses only ultraviolet rays. Thus, a dye absorbing visible light is prepared and used together with a catalyst so that TiO ₂ uses both ultraviolet rays and visible light. The visible light dye has (+) polarity, and the surface of the catalyst TiO ₂ has (-) polarity, and the polarity difference causes the dye to approach the surface of the catalyst and to transfer electrons. In order to maximize this phenomenon, in the present invention, a Nafion layer having a greater (-) polarity is formed on the surface of TiO ₂ to maximize the electron transferring effect, and the dye and the catalyst are integrated And to make photocatalyst for decomposition of visible visible light water.

The Nf / Pt-TiO ₂ catalyst can be prepared as shown in the following reaction formula (2).

[Reaction Scheme 2]

Referring to Scheme 2, the loading of platinum (platinum) on TiO ₂ surface, and forming a Nafion layer on TiO ₂ surface of the platinum loading.

The loading of platinum can be carried out by light reduction using light, thermal reduction using ethylene glycol, or chemical reduction using NaBH ₄ (sodium borohydride) according to a conventional method. In particular, loading of platinum by chemical reduction is effective It is better on the side.

Specifically, the platinum loading can be performed according to a chemical reduction method in which TiO ₂ powder as a catalyst is impregnated with an aqueous solution of chloroplatinic acid (H ₂ PtCl ₆ .H ₂ O), NaBH ₄ is added, and stirring is continued.

The amount of platinum loaded on the TiO ₂ catalyst is preferably 1 to 10 wt%, more preferably 5 wt%, based on the total weight of TiO ₂ . When the content is less than 1% by weight, the amount of cocatalyst in which hydrogen is produced is insufficient and hydrogen generation may be small. When the content exceeds 10% by weight, platinum-loaded TiO ₂ becomes too black, The surface area of the catalyst is reduced and hydrogen generation can be reduced because the position of receiving light is small.

Then, a nafion layer is formed on the surface of the platinum-loaded TiO ₂ (Pt-TiO ₂ ) as described above. Specifically, the Pt-TiO ₂ powder was mixed in a Nafion solution and then dried at 80 to 100 ° C, preferably 90 ° C for about 10 minutes to obtain a Naf / Pt-TiO ₂ powder having a Nafion layer formed on the surface of Pt- TiO ₂ can be obtained.

The Nafion layer is preferably formed to a thickness of 1 ~ 20㎚ on the surface of the Pt-TiO ₂ such that 10 to 35% by weight relative to the total weight of TiO _2. When the content is less than 10% by weight, it may not be completely cured on the surface, and when it exceeds 35% by weight, light may not reach the surface.

The Nf / Pt-TiO ₂ thus prepared has a (-) polarity as a whole coated with a Nafion layer on its surface.

(S3) SnP ⁶⁺ / Nf / Pt-TiO ₂  Photocatalyst manufacturing

Finally, by combining the SnP ⁶⁺ and Nf / Pt-TiO ₂ prepared as described above to produce an ^{SnP 6+ / Nf / Pt-TiO} 2 photocatalyst.

Specifically, after dissolving the dye in the visible light of the above prepared SnP ⁶⁺ in distilled water was added to the Nf / Pt-TiO ₂ catalyst was strongly stirred by a SnP ⁶⁺ absorbed by the Nafion layer of Nf / Pt-TiO ₂ surface SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst can be produced. At this time, it is preferable to stir at a high speed for 30 minutes or more so that SnP ⁶⁺ , which is a visible light dye, can be sufficiently absorbed by the Nf / Pt-TiO ₂ catalyst.

The ^{SnP 6+ / Nf / Pt-TiO} 2 photocatalyst of SnP ⁶⁺ is preferably contained at 0.1 to 10% by weight based on the total weight of the photocatalyst, and more preferably from 0.3 to 1% by weight, most preferably from 0.5 wt. %. When the content is less than 0.1% by weight, the hydrogen production efficiency is insufficient because it can not absorb a lot of light. When the content exceeds 10% by weight, the amount of the dye increases, The amount of the catalyst to be used is limited, which may limit the electron transport.

The SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared as described above can generate hydrogen in the entire pH range, unlike TiO ₂ , which undergoes water decomposition under acidic conditions below pH 5. That is, the SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst of the present invention can overcome the problem of low hydrogen generation at neutral by coating the Nafion layer, The hydrogen production rate can be remarkably improved by controlling the amount of nafion coated on the surface of the catalyst and the amount of dye adsorbed on the nafion layer.

The present invention also provides a composition for producing water-decomposed hydrogen containing SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst and water prepared as described above.

The SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst is contained in an amount of 1 to 5 g / L, more preferably 1 to 2 g / L, based on 1.0 g / L of water, Preferably 1.5 g / L. When the content is less than 1 g / L, the amount of the catalyst used in the reaction is too small to reduce the hydrogen production efficiency. When the content exceeds 5 g / L, the amount of the catalyst is too large, The hydrogen generation efficiency can be reduced.

The composition for hydrogen generation may further include an electron donor compound for efficient hydrogen generation.

The electron donor compound may be ethylenediaminetetraacetic acid (EDTA), alcohol such as methanol, organic acid, or the like. The content of the catalyst may be in the range of 50-1,000 parts by weight based on 100 parts by weight of the photocatalyst. If the amount is less than 50 parts by weight, the electron donating activity may be weakened. If the amount exceeds 1,000 parts by weight, Can be lowered.

The pH of the composition for producing hydrogenated hydrogen is preferably 3 to 9, more preferably 6 to 8. When the pH of the composition is less than 3, the porphyrin used as a dye may be replaced with florin and chlorine to lose its role as a dye. If the pH of the composition is more than 9, the Nafion film coated on the surface of the catalyst may be peeled off, The state can not work and efficiency can be reduced. In addition, a compound such as nitric acid, perchloric acid, or sodium hydroxide may be added to the composition for hydrogen generation to control the pH.

Further, the present invention provides a method for producing hydrogen by water decomposition, which comprises the step of supplying a gas to the composition for hydrogen generation and then irradiating light, wherein the hydrogen generation method is a method of decomposing water by a conventional water decomposition method .

The gas may be supplied with nitrogen, argon, helium gas or the like, and it is particularly preferable to use nitrogen in terms of cost.

The light irradiation may be an Xe-arc lamp, a halogen lamp, a high-pressure mercury lamp, a laser beam, a metal halide lamp, a black lamp, an electrodeless lamp, or the like. In addition, in order to remove ultraviolet rays and use only visible light, it is preferable to use only light having a wavelength of 420 nm or more by using a visible light filter, and more preferably, light of 420 to 600 nm is used.

Further, in order to remove the thermal effect during light irradiation, a cooling device is placed in front of the light source so that the reaction temperature is preferably 40 ° C or less, more preferably 20 to 40 ° C.

Hereinafter, the present invention will be described in more detail with reference to examples. These embodiments are for purposes of illustration only and are not intended to limit the scope of protection of the present invention.

The materials used in the following Examples and Experimental Examples were purchased and used as follows. (Aldrich), tin chloride (II) hydrate (JANSSEN), potassium carbonate (Junsei), and the like), a mixture of TiO ₂ powder (Degussa P25) and Nafion (Aldrich's alcohol and water mixed 5 wt% , N, N ' , N' -tetramethyluronium hexafluorophosphate (TFA), chloroplatinic acid (H ₂ PtCl ₆ .6H ₂ O, Alfa), ethylenediaminetetraacetic acid (EDTA, Junsei), sodium borohydride (NaBH ₄ , Aldrich), tetrahydrofuran (JT Baker, HPLC solvent), nitric acid (Junsei), dichloromethane (CH ₂ Cl ₂ , JT Baker, HPLC solvent), dimethylformamide (DMF, Junsei) ). Sodium hydroxide (Junsei) and ultrapure water were prepared by a water purification system (Human Co.).

In addition, the TEM (TEM-EDS) and S-TEM images were measured using JEOL / JEM 2100, and the zeta potential of the catalyst particles in the aqueous suspension was measured with an electrophoretic light scattering spectrophotometer (ELSZ-2, Otsuka). The light absorption spectra and the UV-visible spectra were measured using a UV-vis spectrophotometer (UV-3600, Shimadzu). Surface atomic composition was measured by X-ray photoelectron spectroscopy (XPS, ULVAC-PHI / Quantera) and infrared spectroscopy (FT-IR spectra) was taken at 4000-400 cm ^-1 in Bruker / Vertex 80v. Thermogravimetric analysis (TGA) was measured using TA Instruments / Auto-TGA Q502 while heating from room temperature to 600 ° C under nitrogen at a heating rate of 5 ° C / min. ¹ H NMR spectroscopy was performed using a Bruker / AVANCE III 400 Micro Bay spectrometer.

Example 1 Synthesis of Visible Light Dye [Sn (OH ₂ ) ₂ TPy ^H P (4)] ⁶⁺ (SnP ⁶⁺ ) Produce

1-1. Preparation of 5,10,15,20-tetrakis (4-pyridyl) porphyrin

0.04 mol of refined pyrrole and 0.04 mol of 4-pyridinecarboxaldehyde were dissolved in 250 mL of propionic acid and reacted at 140 DEG C for 2 hours under reflux. After removing propionic acid, it was immersed in dimethylformamide (DMF) for one day, filtered, and the resulting crude product was purified by column chromatography (dichloromethane and methanol 1/5). The product was recrystallized from a dichloromethane and n-hexane solution to give 5,10,15,20-tetrakis (4-pyridyl) porphyrin 5,10,15,20-tetrakis (4-pyridyl) porphyrin , 10,15,20-tetrakis (4-pyridyl) porphyrin, H ₂ TPyP (4)).

The results of analysis of the H ₂ TPyP (4) prepared above using ¹ H NMR spectroscopy are shown in FIG.

As shown in FIG. 1, it was confirmed that the proton peak of? -Pyrrolic appeared at 8.8 ppm. In addition, the proton peaks at the 2 and 6 positions of pyridine showed the peak at 9.0 ppm, and the proton peaks at the 3 and 5 positions showed 8.1 ppm. It was also confirmed that the protons of pyrrole in porphyrin appeared at -2.9 ppm. From these results, it was confirmed that H ₂ TPyP (4) was successfully synthesized.

Yield: 1.20 g (20%) , 1 H NMR (400 MHz, CDCl 3): δ 9.05 (d, 8H, H py-α), 8.85 (s, 8H, H β-pyrrolic), 8.14 (s, 8H , H _{py -?} ), -2.94 (s, 2H, H _pyrrole ) ppm.

1-2. Preparation of trans-dichloro [5,10,15,20-tetrakis (4-pyridyl) porphyrin] tin (IV)

1.20 g (1.95 mmol) of the prepared H ₂ TPyP (4) was dissolved in 250 mL of pyridine and 0.873 g (3.90 mmol) of tin (II) chloride dihydrate, SnCl ₂ was added. The mixture was refluxed and reacted at 120 DEG C until the reaction was completed. The reaction procedure was monitored by thin layer chromatography. After 10 hours, the residue was dissolved in dichloromethane, filtered using celite, and then recrystallized from dichloromethane and n-hexane to obtain a purple crystal of trans-dichloro [5,10,15,20-tetrakis pyridyl) porphyrin] tin (ⅳ) (trans -dichloro [5,10,15,20 -tetrakis (4-pyridyl) porphyrin] tin (ⅳ), SnCl 2 to give the TPyP (4)). The product was filtered, washed with cold water and dried in a vacuum oven.

The results of analysis of the SnCl ₂ TPyP (4) prepared above using ¹ H NMR spectroscopy are shown in FIG.

As shown in FIG. 2, it was confirmed that the proton peak of β-pyrrolic was shifted downfield by the influence of tin in the porphyrin ring as compared with H ₂ TPyP (4). In the case of proton, 8H , 8H and 8H, respectively. However, the absence of proton peaks of pyrrole at -2.9 ppm inside the porphyrin indicated that the two protons inside were lost, and it was predicted that the tin was substituted at that position, and thus SnCl ₂ TPyP (4 ) Was synthesized.

Yield: 1.5 g (98%) , 1 H NMR (400 MHz, CDCl 3): δ 9.23 (s, 8H, H β-pyrrolic), 9.14 (d, 8H, H py-α), 8.26 (s, 8H , H _{py -?} ) Ppm

1-3. Preparation of trans-dihydroxy [5,10,15,20-tetrakis (4-pyridyl) porphyrin] tin (IV)

0.9 g (1.116 mmol) of SnCl ₂ TPyP (4) prepared above was dissolved in 200 mL of tetrahydrofuran (THF). A solution of 2.28 g (17.78 mmol) of potassium carbonate (K ₂ CO ₃ ) in 100 mL of distilled water was added to the solution, and the mixture was reacted at 80 ° C. for 4 hours under reflux.

The reaction mixture was concentrated using a rotary evaporator to remove tetrahydrofuran, and then allowed to stand in a refrigerator for one day to obtain a purple microcrystalline trans-dihydroxy [5,10,15,20-tetrakis (4- pyridyl) porphyrin] tin (ⅳ) (trans -dihydroxo [5,10,15,20 -tetrakis (4-pyridyl) porphyrin] tin (ⅳ), Sn (OH) 2 to give a TPyP (4)). The product was filtered, washed with cold water and dried in a vacuum oven.

The results of analysis of the Sn (OH) ₂ TPyP (4) prepared above using ¹ H NMR spectroscopy are shown in FIG.

As shown in FIG. 3, it was confirmed that the proton of OH coordinated to the tin atom was affected by the ring current of the porphyrin ligand and appeared at -7.4 ppm, which is the up field region. As a result, Direction was successfully replaced by OH groups. It was also confirmed that the protons at positions 2, 6 and 3, 5 of β-pyrrolic and pyridine were 8H, 8H and 8H, indicating porphyrin structure.

Yield: 0.46 g (79%) , 1 H NMR (400 MHz, CDCl 3): δ 9.15 (s 8H, H β-pyrrolic.), 9.12 (d, 8H, H py-α), 8.26 (s, 8H , H _{py -?} ) Ppm.

1-4. [Sn (OH ₂ ) ₂ TPy ^H P (4)] ⁶⁺  Produce

385 mg (0.5 mmol) of Sn (OH) ₂ TPyP (4) prepared above was dissolved in 5 mL of 1% nitric acid aqueous solution, and then 50 mL of acetone was layered and left for 3 days to obtain [ Sn (OH ₂ ) ₂ TPy ^H P (4)] ⁶⁺ (SnP ⁶⁺ ). The product was filtered, washed with cold water and dried in a vacuum oven.

The result of analysis of the Sn (OH ₂ ) ₂ TPy ^H P (4) (SnP ⁶⁺ ) prepared above by ¹ H NMR spectroscopy is shown in FIG.

As shown in Figure 4, SnP ⁶⁺ There was a blood β- rolrik and 2, 6 and 3, protons of one 5-position of the pyridine such as a synthetic porphyrin can check the front to appear 8H, 8H, 8H, prior But did not show a large difference from the synthesized Sn (OH) ₂ TPyP (4).

Sn (OH) ₂ TPyP (4) did not dissolve in distilled water, but SnP ⁶⁺ was found to dissolve in D ₂ O, where protons were replaced with deuterium in H ₂ O. In addition, peeling of the proton at positions 2 and 6 of pyridine was weakened, indicating weaker down-field shift than before, and distance from the proton at the β-pyrrolic c position was distanced, indicating that SnP ⁶⁺ was successful Was synthesized.

Yield: 370.0 mg (95%) , 1 H NMR (400 MHz, D 2 O): δ 9.55 (s 8H, H β-pyrrolic.), 9.32 (d, 8H, H py-α), 8.94 (s, 8H, H _py-B ) ppm.

Experimental Example 1. SnP ⁶⁺ Absorbance measurement

To confirm whether SnP ⁶⁺ prepared in Example 1 absorbs light in the visible light region, SnP ⁶⁺ was dissolved in distilled water, and the absorbance was measured with a UV-vis spectrophotometer (UV-3600, Shimadzu) 5.

As shown in FIG. 5, it was confirmed that the soret band, which is the most characteristic feature of the porphyrin compound, appears at 414 nm, and it was confirmed that the sorptive band at 550 nm, 588 nm, and 623 nm - I was able to identify the band. From these results, it was confirmed that the light absorption was observed in the visible light region of SnP ⁶⁺ prepared in Example 1, and that the synthesized dye could be used as a water-decomposable visible light dye.

Example 2. Nf / Pt-TiO ₂  Produce

2-1. Platinum (Pt) loaded TiO ₂  Preparation (Pt-TiO ₂ ) Produce

Loading of platinum on the TiO ₂ surface was performed by chemical reduction. First, 0.5 g of TiO ₂ powder (diameter: about 20 nm) was impregnated in 200 mL of an aqueous solution of 0.1 M chloroplatinic acid (H ₂ PtCl ₆ .H ₂ O) for 2 hours, and stirring was continued for 2 hours. Then, NaBH ₄ (0.1 mM NaBH ₄ in methanol) was rapidly added to the reaction solution, followed by stirring for 2 hours. The color of platinum-loaded TiO ₂ changed from white to black depending on the reaction. The powder was washed with distilled water, the suspension was centrifuged and filtered, and the obtained residue was dried at 80 캜 to obtain 0.512 g of Pt-TiO ₂ powder.

2-2. The Nafion layer formed catalyst (Nf / Pt-TiO ₂ ) Produce

0.1 g of the prepared Pt-TiO ₂ powder was added to 0.1 ml of Nafion solution, and the mixture was dried at 90 ° C for 10 minutes to obtain 0.125 g of Nf / Pt-TiO ₂ powder.

Experimental Example 2. Nf / Pt-TiO ₂  Structure analysis of catalyst

The structures of Pt-TiO ₂ and Nf / Pt-TiO ₂ prepared in Example 2 were analyzed using TEM, TEM-EDS, XPS and FT-IR.

First, the Pt-TiO ₂ catalyst was confirmed by TEM, and it was confirmed whether or not the platinum was properly loaded by TEM-EDS, and the result is shown in FIG. The results of analysis of the Nf / Pt-TiO ₂ catalyst using TEM-EDS, XPS and FT-IR are shown in FIGS.

In the TEM image of FIG. 6A, it was confirmed that the TiO ₂ particles having a gray round shape were loaded with platinum particles, which are black dots on the TiO ₂ surface. The EDS image of FIG. 6B shows the elemental analysis results of the Pt-TiO ₂ catalyst, indicating that platinum is present on the TiO ₂ surface, indicating that the Pt-TiO ₂ catalyst was synthesized. Also, the direct distribution of Ti, Pt and O can be confirmed through the S-TEM image of FIG. 6C.

TiO ₂ particles and platinum particles can be identified in the TEM image of FIG. 7A. It was confirmed that a thin film was coated on the surface of the TiO ₂ particle which appeared as a lattice between the two red arrows. Also, the results of the EDS in FIG. 7 (b) confirmed that titanium and oxygen of TiO ₂ particles, platinum of platinum particles, and fluorine and sulfur, which constitute Nafion, can be identified.

As a result of the presence of elements constituting Nf / Pt-TiO ₂ through XPS, the presence of Nf / Pt-TiO ₂ (red line) and TiO ₂ (black line) It was confirmed that Ti 2p _1/2 of the basic titanium is 464 eV and Ti 2p _3/2 is 45 eV. It was also confirmed that Nf / Pt-TiO ₂ showed 1s of fluorine, which is the main component of Nafion, at 687eV. On the other hand, fluorine was not detected in the general TiO ₂ used as a control, and it was confirmed that the Nafion layer was present in the Nf / Pt-TiO ₂ prepared in Example 2.

The results of analysis using FT-IR to more clearly verify the presence of the Nafion layer are shown in FIG. As shown in Fig. 9, CF vibration was observed at 1,239 cm ^-1 of Nf / Pt-TiO ₂ (red line) in which the Nafion layer was formed, but not in TiO ₂ (black line). In addition, Ti-O vibrations were observed at 728 cm ^-1 in both Nf / Pt-TiO ₂ and TiO ₂ . Through the results as described above were able to compare the conditions before and after the before and after the Nafion coating coating of Nafion, to consequently Nf / Pt-TiO ₂ Nafion basic constituents of fluoro children exist as viewed Pt-TiO _2, which of the I It was confirmed that the Pion layer was successfully formed.

Example 3. SnP ⁶⁺ / Nf / Pt-TiO ₂  Photocatalyst manufacturing

The SnP ⁶⁺ prepared in Example 1 was dissolved in distilled water and added to the Nf / Pt-TiO ₂ catalyst prepared in Example 2. In the case of the catalyst, since Nafion was not coated and floated on the surface of the distilled water, the Nafion layer formed on the surface of the Nf / Pt-TiO ₂ catalyst was strongly adsorbed to uniformly mix SnP ⁶⁺ . The reaction solution was centrifuged and dried to completely remove the solution to obtain a SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst in which SnP ^{6+ as a} visible light dye was absorbed.

In order to confirm the degree of absorption of SnP ^{6+ as} a visible light dye, Nf / Pt-TiO ₂ catalyst was added to a solution in which SnP ⁶⁺ was dissolved at a constant concentration using a UV-vis spectrometer. The spectrum of the solution was confirmed at intervals of minutes. The results are shown in Fig.

As shown in FIG. 10, the Nf / Pt-TiO ₂ catalyst (a) in which the Nafion layer was formed showed that the solution became transparent and the sieve band of the dye gradually decreased with time. On the other hand, the TiO ₂ catalyst, which was tested under the same conditions as the control group, visually showed that the color of the solution was unchanged from the beginning, and that the sorret band appeared as it was. The degree of reduction of the dye is represented by a graph based on the sirt band and is shown in Fig.

As shown in FIG. 11, the dye was absorbed at a high rate up to 5 minutes, and the absorption rate was slowed after 5 minutes, but it was almost completely absorbed in about 25 minutes. Based on these results, the time required for completely blocking the light in the actual water decomposition experiment was set to 30 minutes or longer, and the dye was sufficiently stirred so as to be completely absorbed into the catalyst.

Experimental Example 3: SnP ⁶⁺ / Nf / Pt-TiO ₂  Dye characteristics of photocatalyst

3-1. reflectivity

The reflectance of the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst powder prepared in Example 3 was measured and then the reflection spectrum was converted into an absorption spectrum using the Kubelka-Munk theory. The results are shown in FIG. At this time, a general TiO ₂ catalyst and Nafion coated TiO ₂ (Nf / TiO ₂ ) were used as a control group.

Experimental results As shown in Fig. 12, in the case of Nf / TiO ₂ and TiO ₂ , no particular reaction was observed in the visible light region, and only the ultraviolet region of less than 400 nm showed absorption. A slight noise was found due to scattering by the Nafion layer coated on the catalyst between 300 and 350 nm. On the other hand, SnP ⁶⁺ / Nf / Pt-TiO ₂ prepared in Example 3 showed absorption in the visible light region. In particular, peaks appeared in the 414 nm, 511 nm, 550 nm and 588 nm regions, and these peaks were at the same positions as the absorption peaks of the absorbed visible light dyes SnP ⁶⁺ . From these results, it was found that the visible light dye SnP ⁶⁺ was well absorbed into the Nf / Pt-TiO ₂ catalyst.

3-2. Surface polarity

To investigate the polarity of the surface of the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared in Example 3 and to determine the degree of mobility in distilled water as a main solution, the surface polarity was measured using zeta potential And the results are shown in Table 1 below.

catalyst pH TiO ₂ SnP ⁶⁺ / TiO ₂ Nf / TiO ₂ SnP ⁶⁺ / Nf / Pt-TiO ₂ Zeta potential
(mV) 7 -8.8 -14.5 -28.5 20.9

As shown in Table 1, it can be seen that SnP ^{6 +} / TiO ₂ , which is not adsorbed properly, does not change to the negative polarity of TiO ₂ . On the other hand, in the case of the SnP ^{6 +} / Nf / Pt-TiO ₂ adsorbed in the visible light dye prepared in Example 3, the polarity was reversed and the polarity of the dye was (+).

3-3. TGA

In order to confirm how much dye was absorbed into the SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst prepared in Example 3, the organic material was burned while increasing the temperature, and the amount of the dye was measured using TGA . In order to determine the maximum amount of dye adsorption during the preparation of the sample, SnP ^{6 +} / Nf / Pt-TiO ₂ catalyst was added to the solution in which excess dye was dissolved, and sufficient time was adsorbed for analysis. The results are shown in Fig.

As shown in FIG. 13, it was confirmed that SnP ^{6+, which} is a visible light dye, sharply decreased from 150 ° C and steadily decreased to 600 ° C. In addition, a steep slope was observed at two times because the amount of water remaining in the porphyrin decreased until the first 150 ° C and porphyrin began to decrease at 350 ° C. In addition, it was confirmed that the Nafion started to decompose rapidly at 300 ° C, while the moisture gradually disappeared, and it was confirmed that it decreased to 97% by weight at 500 ° C. Also, it was observed that the Nafion-coated catalyst (Nf / TiO ₂ ) also decreased at 300 ° C. In the case of Nf / TiO ₂ in which no dye was absorbed, the amount of SnP ^{6 +} / Nf / TiO ₂ of Example 3 decreased by 260 wt% Is a region where naphion and dye are decomposed together, and then it is confirmed that the amount of naphion is reduced to 9 wt% by the continuous decrease of naphion. When the results are compared, it was found that the amount of SnP ^{6 +} as a visible light dye absorbed in the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared in Example 3 was about 3 wt%.

3-4. TEM-EDS

The SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared in Example 3 was measured by TEM-EDS and the results are shown in FIG.

As shown in FIG. 14, the TiO ₂ particles and the platinum particles could be confirmed visually, and a transparent film (Nafion layer) coated on the periphery of the particles could be confirmed (left side in FIG. 14). As a result of confirming the Nafion layer and SnP ⁶⁺ using EDS, as shown in the right side of FIG. 14, it was confirmed that the amount of fluorine and sulfur was larger than the previously confirmed EDS. And tin of Ti and tin porphyrin.

From the above results, it was found that the Nafion layer was formed on the surface of the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared in Example 3, and tin porphyrin was present in the formed Nafion layer.

Example 4. Preparation of water-decomposable hydrogen production composition

0.075 g of the SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst prepared in Example 3 was added to 5 mL of distilled water. 1 mM of ethylenediaminetetraacetic acid (EDTA) was added thereto, followed by stirring to prepare a composition for producing water-decomposed hydrogen.

Experimental example 4. Water decomposition test

A water decomposition test was conducted using the composition for hydrogen generation of Example 4 above. The amount of visible light dye, the amount of catalyst, and the stability of the catalyst in the water decomposition test were evaluated as follows.

4-1. Amount of dye

The water decomposition test was conducted while adjusting the amount of the dye in the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst used in the composition for hydrogen generation in Example 4. First, the same amount of EDTA (1 mM) and SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst (2.0 g / L) were tested on the basis of 5 mL of distilled water. At this time, the amount of SnP ^{6 +} , a visible light dye absorbed in the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst, was controlled to 0.01, 0.05, 0.1, 0.5, 1 mM and the degree of hydrogen production was confirmed. The results are shown in Fig.

As shown in FIG. 15, the amount of visible light showed the best hydrogen production from 0.1 mM to 100 μmol, and showed hydrogen production from 0.5 mM to 68 μmol. On the other hand, 20mol of hydrogen was produced on the basis of 120mins at 1mM at which the most dye was absorbed. Therefore, the following experiment was carried out with the amount of visible light dye being 0.1 mM.

4-2. Amount of catalyst

A water decomposition test was conducted while controlling the amount of SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst used in the composition for hydrogen generation of Example 4. First, the same amounts of EDTA (1 mM) and SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalysts were tested at different concentrations of 2.0 g / L, 1.5 g / L and 1.0 g / L based on 5 mL of distilled water. At this time, the amount of SnP ⁶⁺ as a visible light dye absorbed in the SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst was 0.1 mM. The water was decomposed for 120 minutes and analyzed by GC at regular intervals. The results are shown in FIG.

As shown in FIG. 16, when 1.0 g / L of SnP ⁶⁺ / Nf / Pt-TiO ₂ was used, 52 μmol of hydrogen was produced in 120 minutes, and when it was used at 1.5 g / L, 193 μmol and 2.0 g / Hydrogen peroxide was produced. These results indicate that the amount of the catalyst becomes opaque when the amount of the catalyst is increased and the dye can not properly absorb the light due to the occlusion of the catalysts, It is because it falls.

4-3. Stability of catalyst

In order to measure the efficiency of hydrogen production using the composition for hydrogen generation of Example 4, the extent to which hydrogen was generated was measured using a solution in which excess EDTA was dissolved, and the results are shown in FIG.

As shown in Fig. 17, it was confirmed that the hydrogen generation was the best after 75 minutes from the application of light, and thereafter, the hydrogen production was decreased. In order to completely remove the generated hydrogen gas, nitrogen was injected for 1 hour, and then light was again irradiated. As a result, hydrogen was again produced for 135 minutes and then stagnated again. Nitrogen was further injected for 1 hour After the remeasurement, hydrogen was no longer produced. This result is due to the fact that the porphyrin is converted into chlorine at pH 3, and the reaction does not progress anymore. In the next step, hydrogen Production was confirmed.

As a result, as shown in FIG. 18, it was confirmed that when the dye was kept constant, the hydrogen production amount was steadily increased for 10 hours.

Experimental Example 5. Measurement of Hydrogen Production Rate by pH

The porphyrin reacts with EDTA and reacts with the hydrogen ion generated in the water decomposition process to convert into florin and chlorine, and the generated florin reacts with platinum of the catalyst to produce hydrogen. Florin is converted back into porphyrin after hydrogen production through the reaction, but chlorine does not react and does not return to the form of porphyrin again. As the chlorine is produced, it fails to transfer electrons and the reaction is terminated. That is, as the chlorine in the solution increases, the porphyrin is reduced and the dye does not function.

In order to confirm the change of porphyrin dye according to the pH change during the water decomposition reaction, the pH was kept constant at 4, 7, 9 in a state where the EDTA amount was kept constant and then left for 72 hours. Was confirmed by the UV-vis spectrum. At this time, to maintain the pH constant, a buffer solution corresponding to pH 4, 7, or 9 was prepared.

As shown in Fig. 19, the solutions in pH 3 and pH 4, which were in the weak acid state, showed green color of chlorine, and in the neutral pH 7 and pH 9, the purine color of porphyrin was maintained there was. This is consistent with previous data that porphyrin does not change to chlorine and florine at pH> 5.

The resultant solution was measured using a UV-vis spectrum. As a result, as shown in Fig. 20, pH 7 and pH 9 showed little difference from the values measured at the start. However, in the case of pH 4, it was confirmed that the structure of porphyrin was changed and the peaks of 412 nm and 550 nm were reduced and the peak of 630 nm was enlarged. On the other hand, pH 7 and pH 9 showed almost no difference from the values measured at the start, and it was confirmed that the porphyrin dye was stably maintained at pH 7 and pH 9.

Next, the hydrogen production rate at each pH was measured, and the result is shown in FIG. Experimental results show that most of the hydrogen was produced in the pH 7 environment where the least amount of hydrogen was generated in the experiment using the existing porphyrin. That is, the hydrogen production according to the pH of the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst was measured to be 1,142 μmol at pH 7, 200 μmol at pH 9, and 181 μmol at pH 3 based on the reaction of 300 minutes. In the case of pH 3, the reaction appeared to be complete in 100 minutes, probably because the porphyrin was converted to chlorine and the reaction did not proceed any further. On the contrary, it was confirmed that the pH 9 continuously increased and exceeded the amount of hydrogen generated at pH 3 at 240 minutes.

Therefore, it was confirmed that the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst prepared according to the present invention can generate hydrogen in the entire pH range unlike the conventional TiO ₂ , and the efficiency thereof is remarkably improved as compared with the conventional one.

Although the present invention has been described in terms of the preferred embodiments mentioned above, it is possible to make various modifications and variations without departing from the spirit and scope of the invention. It is also to be understood that the appended claims are intended to cover such modifications and changes as fall within the scope of the invention.

Claims (15)

Platinum loaded TiO ₂ ; And
A polymer (Nafion) layer in which sulfonate groups and tetrafluoroethylene (Teflon) are introduced at the end of a perfluorovinyl ether group formed on the surface of the TiO ₂ ;
Wherein the polymer layer is impregnated with SnP ⁶⁺ , and SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst for producing hydrogenolysis of visible light. The method according to claim 1,
Wherein the TiO ₂ has a diameter of 10 to 100 nm. The SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst for visible light water decomposition hydrogen generation. The method according to claim 1,
Wherein the platinum is loaded in an amount of 1 to 10 wt% based on the total weight of the TiO _{2. 2. The} SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst according to claim _1, The method according to claim 1,
Wherein the polymer layer is formed to a thickness of 1 to 20 nm on the surface of the platinum-loaded TiO ₂ SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst for visible light water decomposition. The method according to claim 1,
SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst for producing visible light water decomposition hydrogen, wherein the SnP ⁶⁺ is contained in an amount of 0.1 to 10 wt% based on the total weight of the photocatalyst. (S1) to prepare a visible dye is _{[Sn (OH 2) 2 TPy} H P (4)] 6+ (SnP 6+);
(S2) A polymer in which sulfonate groups and tetrafluoroethylene (Teflon) are introduced at the end of a perfluorovinyl ether group on the surface of platinum-loaded TiO ₂ Nafion, Nafion) -formed Nf / Pt-TiO ₂ layer; And
(S3) preparing an ^{SnP 6+ / Nf / Pt-TiO} 2 photocatalyst combine SnP ⁶⁺ in the Nf / Pt-TiO _2;
Wherein the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst for visible light hydrolysis hydrogen production is prepared. The method according to claim 6,
The visible light dye in the step (S1)
(a) the pyrrole and pyridine-4-carboxamide by reacting the aldehyde (4-pyridinecarboxaldehyde) a solvent (acid), 5,10,15,20-tetrakis (4-pyridyl) porphyrin (H ₂ TPYP (4)) Synthesizing;
(b) dissolving the 5,10,15,20-tetrakis (4-pyridyl) porphyrin in a solvent (pyridine), adding tin (II) chloride dihydrate and reacting Synthesizing trans-dichloro [5,10,15,20-tetrakis (4-pyridyl) porphyrin] tin (IV) (SnCl ₂ TPyP (4));
(c) adding potassium carbonate (K ₂ CO ₃ ) to the trans-dichloro [5,10,15,20-tetrakis (4-pyridyl) porphyrin] (IV) (Sn (OH) ₂ TPyP (4)) as a starting material; And
(d) the trans-dihydroxy rokso [5,10,15,20-tetrakis (4-pyridyl) porphyrin] by acid treatment in the tin (Ⅳ) [Sn (OH _{2) 2} ^H TPy P (4); ^{6 +} (SnP ⁶⁺ );
Wherein the SnP ^{6 +} / Nf / Pt-TiO ₂ photocatalyst is produced by a method comprising the steps of: 8. The method of claim 7,
A process for producing a SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst for visible light decomposition hydrogen production, characterized in that the acid treatment of (d) is treated with at least one acid solution selected from nitric acid, hydrochloric acid, sulfuric acid and phosphoric acid . The method according to claim 6,
The (S2) Nf / Pt-TiO ₂ phase on the TiO ₂ surface of platinum (Pt) is TiO ₂ with respect to the total weight of 1 to 10 for the SnP visible water decomposition hydrogen produced, characterized in that the loading in weight percent of ^{6 +} / A method for producing a Nf / Pt-TiO ₂ photocatalyst. The method according to claim 6,
The (S2) Nf / Pt-TiO ₂ phase of the platinum loading of TiO ₂ polymer layer is TiO ₂ with respect to the total weight of 10-35% visible light, water decomposition, characterized in that formed in the hydrogen generation for the surface weight of SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst. The method according to claim 6,
The (S3) SnP ⁶⁺ in step Nf / Pt-TiO ₂ for visible light, the water decomposition hydrogen produced, characterized in that included as 0.1 to 10% by weight relative to the total weight of the photocatalyst ^{SnP 6+ / Nf / Pt-TiO} 2 photocatalyst ≪ / RTI > A composition for producing hydrogen-decomposing visible light comprising the SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst according to claim ₁ and water. 13. The method of claim 12,
Wherein the SnP ⁶⁺ / Nf / Pt-TiO ₂ photocatalyst is contained in an amount of 1 to 5 g / L based on 1.0 g / L of water. 13. The method of claim 12,
Wherein the composition for hydrogen generation further comprises at least one electron donor compound selected from ethylenediaminetetraacetic acid, an alcohol and an organic acid. A method for producing visible visible water decomposition hydrogen comprising the steps of supplying at least one selected from nitrogen, argon and helium gas to a visible light decomposition hydrogen generating composition according to claim 12 and then irradiating light.

Images