KR20230068079A - Graphene oxide-titanium dioxide photocatalyst manufacturing method, and photocatalyst prepared accordingly - Google Patents

Abstract

One embodiment of the present invention, (i) preparing titanium dioxide; (ii) mixing the titanium dioxide and carbon precursor; and (iii) calcining the mixture of step (ii).
According to the present invention, it is possible to provide a titanium dioxide-based photocatalyst capable of carrying out a catalytic reaction of a carbon dioxide substitution reaction under visible light without a high energy source such as ultraviolet light or a high heat energy source, and its efficiency is also remarkably improved.

Description

Method for preparing graphene oxide-titanium dioxide photocatalyst and photocatalyst prepared thereby

The present invention relates to a titanium dioxide photocatalyst, and more particularly, to a titanium dioxide-based photocatalyst with improved reactivity to visible light using graphene oxide.

In accordance with the Paris Agreement and the UN's National Voluntary Reduction Target (INCD), it is necessary to drastically reduce greenhouse gas emissions.

CCUS (Carbon Capture & Utilization & Storage) technology is attracting attention as a technology for reducing carbon dioxide, but it is limited to point pollution sources such as factories and power plants, and there is a limit to reducing carbon dioxide in the atmosphere generated from transportation and heating.

In addition, most technologies that use catalysts to replace carbon dioxide with fuel sources to reduce atmospheric carbon dioxide generated from transportation and heating require high-temperature heat or ultraviolet light sources, so there is a limit to separately capturing and reacting carbon dioxide in the atmosphere. exist.

For example, in the case of Korean Patent Publication No. 10-2021-0048389 (Title of Invention: Manufacturing Method of Photocatalyst Beads and Photocatalyst Filter Including Photocatalyst Beads), a method for manufacturing granular photocatalyst beads containing titanium dioxide and photocatalyst beads However, in the case of the photocatalytic beads containing the titanium dioxide, there is a problem in that the photocatalytic activity appears only in the ultraviolet region having a wavelength of 400 nm or less.

Therefore, there is an urgent need to develop a photocatalyst technology that can act as a catalyst under a visible light source, that is, sunlight, without an additional high-energy heat source or light source, thereby removing carbon dioxide in the atmosphere or replacing it with a fuel source.

Republic of Korea Patent Publication No. 10-2021-0048389

An object of the present invention to solve the above problems is to provide a photocatalyst capable of serving as a catalyst in a light source in the visible light region by applying graphene oxide having a smaller band gap than TiO ₂ and having improved reactivity due to smooth supply of electrons. is to do

Another object of the present invention is to provide a method for preparing a TiO ₂ photocatalyst with improved reactivity by adding graphene oxide in a simple manner.

The technical problem to be achieved by the present invention is not limited to the above-mentioned technical problem, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description below. There will be.

In order to achieve the above technical problem, one embodiment of the present invention is a graphene oxide-titanium dioxide photocatalyst manufacturing method, comprising: (i) preparing titanium dioxide; (ii) mixing the titanium dioxide and carbon precursor; and (iii) calcining the mixture of step (ii).

In an embodiment of the present invention, the step of preparing the titanium dioxide, (a) stirring and mixing the titanium precursor and the solvent at 80 ℃ or more and 100 ℃ or less; And (b) calcining the mixture of step (a) at 550 ° C or more and 650 ° C or less; it may be characterized in that titanium dioxide is obtained, including.

In an embodiment of the present invention, the titanium precursor in step (a) includes at least one selected from the group consisting of TiO ₂ (anatase), TiO ₂ (P25), Titanium isopropoxide, and combinations thereof. can do.

In an embodiment of the present invention, the titanium dioxide and carbon precursor in step (ii) may be mixed in a weight ratio of 100:1 or more and 100:10 or less.

In an embodiment of the present invention, the step (ii) may be characterized by mixing by stirring at 80 ° C. or more and 100 ° C. or less.

In an embodiment of the present invention, the carbon precursor in step (ii) may include at least one selected from the group consisting of graphene oxide, graphene, reduced-graphene oxide, carbon nanotube, carbon nano-particles, and combinations thereof. can

In an embodiment of the present invention, the calcination in step (iii) may be performed at a temperature of 350° C. or more and 450° C. or less.

In an embodiment of the present invention, the calcination in step (iii) may be performed while raising the temperature at a rate of 1° C./min or more and less than 3° C./min.

In order to achieve the above technical problem, another embodiment of the present invention is a graphene oxide-titanium dioxide photocatalyst prepared according to the above manufacturing method.

In an embodiment of the present invention, the graphene oxide-titanium dioxide photocatalyst may be characterized in that graphene oxide is included in a weight ratio of 100:1 or more and 100:10 or less.

The effect of the present invention according to the configuration as described above does not require high-temperature heat or a strong energy source such as an ultraviolet light source, and a light source in the visible light region can act as a catalyst to replace carbon dioxide in the air.

In addition, since the flow of electrons is improved and the efficiency of the catalyst is improved, the substitution rate of carbon dioxide is increased.

In addition, since the graphene oxide-titanium dioxide photocatalyst having the above advantages can be prepared by a simple method, process cost is reduced, economic feasibility is secured, and there is no difficulty in commercial application because there is no difficulty in application.

The effects of the present invention are not limited to the above effects, and should be understood to include all effects that can be inferred from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a flowchart of a method for preparing a graphene oxide-titanium dioxide photocatalyst according to an embodiment of the present invention.
2 is a schematic diagram showing a mechanism in which titanium dioxide and a graphene oxide-titanium dioxide photocatalyst replace carbon dioxide.
3 is a schematic diagram of a method for preparing a graphene oxide-titanium dioxide photocatalyst according to an embodiment of the present invention.
4 shows (a) titanium dioxide and (b) graphene oxide-titanium dioxide photocatalyst prepared according to the method for manufacturing a graphene oxide-titanium dioxide photocatalyst according to an embodiment of the present invention.
5 is data obtained by measuring the amount of CO ₂ reduction under a visible light source to compare catalytic properties of (a) a titanium dioxide photocatalyst and (b) a graphene oxide-titanium dioxide photocatalyst.
6 is data obtained by measuring the amount of CO ₂ reduction under a visible light source in order to compare the catalytic properties of graphene oxide-titanium photocatalysts prepared at different temperature rise rates in the calcination step.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and, therefore, is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part is said to be "connected (connected, contacted, combined)" with another part, this is not only "directly connected", but also "indirectly connected" with another member in between. "Including cases where In addition, when a part "includes" a certain component, it means that it may further include other components without excluding other components unless otherwise stated.

Terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "include" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Hereinafter, a method for preparing a graphene oxide-titanium dioxide photocatalyst according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart of a method for preparing a graphene oxide-titanium dioxide photocatalyst according to an embodiment of the present invention.

As shown in FIG. 1, the method for producing a graphene oxide-titanium dioxide photocatalyst of the present invention includes: (i) preparing titanium dioxide (S100); (ii) mixing the titanium dioxide and the carbon precursor (S200); and (iii) calcining the mixture of step (ii) (S300).

In detail, the step (i) of preparing titanium dioxide (S100) includes: (a) stirring and mixing the titanium precursor and the solvent at 80° C. or more and 100° C. or less (S110); And (b) calcining the mixture of step (a) at 550 ° C. or more and 650 ° C. or less (S120); including, titanium oxide can be obtained.

A method for preparing a graphene oxide-titanium dioxide photocatalyst, which is an embodiment of the present invention, is a method for improving the reactivity of a photocatalyst by adding graphene oxide to titanium dioxide in a simple manner.

Specifically, the present graphene oxide-titanium dioxide photocatalyst preparation method is manufactured only through stirring and calcination processes, so a complicated synthesis process is not required, and thus has a simple advantage over the conventional graphene oxide-titanium dioxide photocatalyst preparation method.

In addition, it has the advantage of further improving the reactivity of the graphene oxide-titanium dioxide photocatalyst only by controlling the temperature and rise rate of the calcination process.

Looking at each configuration in detail below, in an embodiment of the present invention, the titanium precursor and the solvent in step (a) (S110) are stirred and mixed at 80 ° C. or more and 100 ° C. or less. Since the solvent must be sufficiently removed, it must be carried out at 80 ° C. or higher, and it must be lower than the boiling point of the solvent, so it must be carried out at 100 ° C. or lower.

In an embodiment of the present invention, the titanium precursor in step (a) (S110) may include at least one selected from the group consisting of TiO ₂ (anatase), TiO ₂ (P25), titanium isopropoxide, and combinations thereof. there is. However, it is not limited thereto, and any titanium precursor commonly used to synthesize titanium dioxide should be construed as being included therein.

In an embodiment of the present invention, in step (b) (S120), the mixture of step (a) (S110) may be calcined at 550° C. or more and 650° C. or less. Calcination is performed at 550° C. or more because the crystal structure of titanium must be changed, and calcination is preferably performed at 650° C. or less because the properties of titanium must be maintained.

Specifically, at 550 ° C or higher, the crystal structure of titanium dioxide changes from anatase to rutile, and at this time, the anatase and rutile show photo-activity in different wavelength regions. Photo-activity for a desired wavelength can be adjusted by controlling the ratio of the anatase structure and the rutile structure.

For example, in the case of the graphene oxide-titanium dioxide photocatalyst implemented according to the manufacturing method of the present invention, when the step (b) (S120) was performed at 600 ° C., it showed the best activity in the visible light region.

Next, in an embodiment of the present invention, the titanium dioxide and the carbon precursor in step (ii) (S200) may be mixed in a weight ratio of 100:1 or more and 100:10 or less. This is because graphene oxide can be excited and transfer electrons to titanium dioxide when the weight ratio is 100:1 or more, and titanium dioxide can act as a CO ₂ catalyst when the weight ratio is 100:10 or less.

In an embodiment of the present invention, the step (ii) (S200) may be mixed by stirring at 80 ° C. or more and 100 ° C. or less. Since the solvent must be sufficiently removed, it must be carried out at 80 ° C. or higher, and it is preferably carried out at 100 ° C. or lower, since it must be lower than the boiling point of the solvent.

In an embodiment of the present invention, the carbon precursor in step (ii) (S200) is at least one selected from the group consisting of graphene oxide, graphene, reduced-graphene oxide, carbon nanotube, carbon nano-particles, and combinations thereof. can include However, it is not limited thereto, and any carbon-based material that can be commonly used to prepare graphene oxide should be construed as the scope of the present invention.

Next, in an embodiment of the present invention, the calcination of step (iii) (S300) may be performed at a temperature of 350 ° C. or more and 450 ° C. or less. This is because the temperature must be 350°C or higher to form a junction between titanium and graphene, and the temperature must be 450 °C or lower to maintain the junction after forming the junction.

In addition, the calcination of step (iii) (S300) may be performed at a heating rate of 1 ° C./min or more and less than 3 ° C./min. According to the experimental results to be discussed below, it was confirmed that the efficiency of the catalyst varies according to the rate of temperature increase in heating to the temperature at which the calcination is performed.

For example, in the production of a graphene oxide-titanium dioxide photocatalyst according to the production method of the present invention, CO ₂ conversion efficiency under visible light when the heating rate of the calcination step is adjusted to 1°C/min or 3°C/min. was lower than when the catalyst was prepared at 2° C./min, confirming that the heating rate of the calcination step is an important variable in determining the performance of the catalyst.

Specifically, this is because, in order to stably form a junction between titanium and graphene, the temperature must be 1° C./min or more, and the temperature must be less than 3° C./min because the characteristics and crystal structure of titanium and graphene must be maintained.

Hereinafter, a graphene oxide-titanium dioxide photocatalyst according to another embodiment of the present invention will be described with reference to the drawings. In the description, overlapping configurations with the graphene oxide-titanium dioxide photocatalyst manufacturing method should be interpreted in the same way, and overlapping descriptions will be omitted.

2 is a schematic diagram showing a mechanism in which titanium dioxide and a graphene oxide-titanium dioxide photocatalyst replace carbon dioxide. Figure 2 (a) is a schematic diagram of the TiO ₂ catalytic reaction, and Figure 2 (b) is a schematic diagram showing the catalytic reaction of the TiO ₂ photocatalyst to which graphene oxide is applied for comparison.

Referring to FIG. 2, the mechanism when the photocatalyst prepared according to the graphene oxide-titanium dioxide photocatalyst preparation method is used as a catalyst for carbon dioxide substitution reaction will be investigated.

The carbon dioxide substitution reaction of the TiO ₂ photocatalyst proceeds according to the irradiation of a light source and the injection of water (H ₂ O). When the light source is irradiated, CO ₂ is reduced and separated into C and O ₂ by the catalytic reaction of TiO ₂ , and the injected H ₂ O is oxidized and separated into O ₂ and H. Here, the separated C and H form CH ₄ and the remaining atoms combine again to form H ₂ O.

In the case of conventional TiO ₂ , a catalytic reaction occurs only when a UV light source having high energy is irradiated due to a large band gap. At this time, when graphene oxide is applied to TiO ₂ , electron excitation occurs even in visible light, that is, sunlight, due to the relatively small band gap of graphene oxide, and electrons are moved to TiO ₂ to enable a catalytic reaction.

In addition, when graphene oxide is applied to TiO ₂ , photocatalytic reactivity to a visible light source is improved compared to pure TiO ₂ . Graphene oxide applied to TiO ₂ has excellent electron mobility and high surface area, especially because the epoxide (-O-) and hydroxide (-OH) functional groups of graphene oxide increase the reactivity to the water decomposition process. As a result, the flow of electrons is improved by the graphene oxide, and the carbon dioxide replacement rate is increased.

Looking at the product by the photocatalytic reaction, TiO ₂ can be substituted with CO, HCOOH, CH ₃ OH, etc. according to the control of the band gap.

In summary, the photocatalyst prepared according to the graphene oxide-titanium dioxide photocatalyst manufacturing method can undergo a catalytic reaction under visible light conditions without a high-energy source such as high-temperature heat or ultraviolet light as graphene oxide is applied to TiO ₂ , , the catalytic efficiency is also improved.

In particular, when TiO ₂ is used as a photocatalyst for a carbon dioxide substitution reaction in consideration of its excellent selectivity for a carbon dioxide substitution reaction, a significantly superior photocatalyst can be provided compared to conventional TiO ₂ photocatalysts.

In addition, the graphene oxide-titanium dioxide photocatalyst was proposed as a photocatalyst for the carbon dioxide substitution reaction in consideration of the excellent selectivity of titanium dioxide for the carbon dioxide substitution reaction in the embodiment of the present invention, but is not limited thereto, and the TiO ₂ bandgap control It should be interpreted as a photocatalyst for a catalytic reaction within a range that is commonly available through.

For example, the graphene oxide-titanium dioxide photocatalyst can be used as a photocatalyst for nitrogen substitution and VOC (Volatile Organic Compounds) removal reactions.

In an embodiment of the present invention, the graphene oxide may be included in a weight ratio of 100:1 or more and 100:10 or less.

manufacturing example

Preparation of graphene oxide-titanium dioxide photocatalyst

Referring to FIGS. 3 and 4, a method for preparing a graphene oxide-titanium dioxide photocatalyst will be described in detail.

3 is a schematic diagram of a method for preparing a graphene oxide-titanium dioxide photocatalyst according to an embodiment of the present invention.

4 shows (a) titanium dioxide and (b) graphene oxide-titanium dioxide photocatalyst prepared according to the method for manufacturing a graphene oxide-titanium dioxide photocatalyst according to an embodiment of the present invention.

1) Titanium dioxide preparation

10 g of titanium isopropoxide, a titanium precursor, was mixed in 30 ml of an ethanol solvent, put into 150 ml of D.I.

Thereafter, the mixture is calcined in a nitrogen atmosphere and at 550° C. or more and 650° C. or less.

As a post-treatment, milling is performed to obtain titanium dioxide.

2) Preparation of graphene oxide-titanium dioxide photocatalyst

10 g of the obtained titanium dioxide and 0.2 g to 2 g of graphene oxide were mixed by stirring at 80 ° C. or more and 100 ° C. or less for 1 hour, and then dried.

Thereafter, the mixture is calcined under a nitrogen atmosphere and a temperature condition of 350° C. or more and 450° C. or less.

Grinding is performed as a post-treatment to obtain a photocatalyst having a weight ratio of graphene oxide and titanium dioxide of 1:100 to 10:100.

Experimental example 1

Comparison of photocatalytic performance with and without graphene oxide under visible light

1) CO ₂ Reduced amount measurement result

This will be described with reference to FIG. 5 .

5 is data obtained by measuring the amount of CO ₂ reduction under a visible light source to compare catalytic properties of (a) a titanium dioxide photocatalyst and (b) a graphene oxide-titanium dioxide photocatalyst.

This measurement experiment was performed under conditions of room temperature and visible light irradiation. 5(a) and 5(b), the photocatalyst composed of pure TiO ₂ reduced CO ₂ corresponding to about 6 ppm in the measurement range, but the graphene oxide-titanium dioxide photocatalyst according to the present invention reduced CO 2 by about 31 ppm It was confirmed that the photocatalytic performance was improved more than 5 times by reducing the corresponding CO ₂ .

In view of the above results, it is possible to greatly improve the reactivity to a visible light source by more than 5 times with the simple process and control conditions proposed by the present invention, and as a result, it is possible to provide a photocatalyst having excellent activity to a visible light source. Confirmed.

Experimental Example 2

Comparison of photocatalyst performance according to temperature rise rate in calcination step

It will be described with reference to FIG. 6 .

6 is data obtained by measuring the amount of CO ₂ reduction under a visible light source in order to compare the catalytic properties of graphene oxide-titanium photocatalysts prepared at different temperature rise rates in the calcination step.

This experiment was conducted to confirm that the performance of the photocatalyst varies according to the heating rate of the calcination step in preparing the graphene oxide-titanium dioxide photocatalyst and to derive the optimal heating rate condition.

In order to achieve the above experimental purpose, experiments were performed while changing the heating rate to 1 °C/min, 2 °C/min, and 2.9 °C/min under nitrogen gas conditions.

According to FIG. 6, the CO ₂ reduction rate was measured as 67 ppm at a heating rate of 1 °C/min, 77 ppm at a heating rate of 2 °C/min, and 50 ppm at a heating rate of 2.9 °C/min, and the CO ₂ reduction rate was the best at 2 °C/min. Decrease rate is shown.

Through the above results, it was confirmed that the performance of the photocatalyst produced varies depending on the heating rate in the calcination step, and therefore, optimization of the heating rate is an important factor in photocatalyst production. As a result, it was found that the graphene oxide-titanium dioxide photocatalyst calcined at a heating rate of 2°C/min according to the present invention was remarkably excellent in reducing CO ₂ .

The above description of the present invention is for illustrative purposes, and those skilled in the art can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims (10)

(i) preparing titanium dioxide;
(ii) mixing the titanium dioxide and carbon precursor; and
(iii) calcining the mixture of step (ii); characterized in that obtained by including, graphene oxide-titanium dioxide photocatalyst production method. According to claim 1,
The step of preparing the titanium dioxide may include (a) stirring and mixing a titanium precursor and a solvent at 80° C. or more and 100° C. or less; and
(b) calcining the mixture of step (a) at 550 ° C. or more and 650 ° C. or less; characterized in that to obtain titanium dioxide, including graphene oxide-titanium dioxide photocatalyst manufacturing method. According to claim 2,
The titanium precursor in step (a) includes at least one selected from the group consisting of TiO ₂ (anatase), TiO ₂ (P25), titanium isopropoxide, and combinations thereof, graphene oxide-titanium dioxide. Photocatalyst manufacturing method. According to claim 1,
The titanium dioxide and carbon precursor in step (ii) are mixed in a weight ratio of 100: 1 or more and 100: 10 or less, graphene oxide-titanium dioxide photocatalyst manufacturing method. According to claim 1,
The step (ii) is characterized by stirring and mixing at 80 ° C. or more and 100 ° C. or less, graphene oxide-titanium dioxide photocatalyst manufacturing method. According to claim 1,
The carbon precursor in step (ii) includes at least one selected from the group consisting of graphene oxide, graphene, reduced-graphene oxide, carbon nanotube, carbon nano-particles, and combinations thereof, graphene oxide. - Manufacturing method of titanium dioxide photocatalyst. According to claim 1,
The calcination in step (iii) is performed at a temperature of 350 ° C or more and 450 ° C or less, graphene oxide-titanium dioxide photocatalyst manufacturing method. According to claim 1,
The calcination in step (iii) is performed while raising the temperature at a rate of 1 ° C./min or more and less than 3 ° C./min, graphene oxide-titanium dioxide photocatalyst manufacturing method. A graphene oxide-titanium dioxide photocatalyst prepared according to claim 1. According to claim 9,
The graphene oxide-titanium dioxide photocatalyst is characterized in that the graphene oxide is included in a weight ratio of 100: 1 or more and 100: 10 or less, the graphene oxide-titanium dioxide photocatalyst.

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