Photocatalyst for hydrogen peroxide production using polydopamine and titanium dioxide and manufacturing method thereof

Abstract

The present invention relates to a photocatalyst for producing hydrogen peroxide using polydopamine and titanium dioxide and a method for producing the same. The technical gist of the method for producing a photocatalyst for producing hydrogen peroxide using polydopamine and titanium dioxide according to one embodiment of the present invention is to include the steps of: preparing a reaction solution by mixing titanium dioxide particles, dopamine, and water; adjusting the pH of the reaction solution to basic using a basic solution; stirring the reaction solution with the adjusted pH to synthesize a photocatalyst comprising titanium dioxide particles having a polydopamine coating layer formed on their surface; and separating the photocatalyst from the reaction solution and washing the separated photocatalyst to produce the photocatalyst.

Description

Technology Field

[0001] The present invention relates to a photocatalyst for producing hydrogen peroxide using polydopamine and titanium dioxide, and a method for producing the same. Background Technology

[0002] Hydrogen peroxide (H2O2) is rapidly increasing in use as an oxidizer and liquid energy fuel because it does not produce toxic byproducts when used as such. In line with this trend, research and development of technologies to produce hydrogen peroxide is actively underway.

[0003] Generally, the production of hydrogen peroxide is carried out through the anthraquinone process, which involves sequentially reducing and oxidizing anthraquinone under a catalyst. However, the aforementioned process using anthraquinone requires expensive precious metal catalysts such as palladium, generates toxic byproducts, and has the problem of consuming a large amount of energy as it involves multiple steps such as hydrogenation and oxidation of anthraquinone molecules, extraction, purification, and concentration to produce hydrogen peroxide.

[0004] To overcome these problems, active research and development is currently underway on a process for generating hydrogen peroxide through an oxygen reduction reaction (ORR) using solar energy as an energy source.

[0005] Generally, the process of generating hydrogen peroxide through ORR using solar energy as an energy source is known to utilize inorganic metal oxide-based photocatalysts such as titanium dioxide (TiO2) and zinc oxide (ZnO).

[0006] However, when hydrogen peroxide is produced using inorganic metal oxide-based photocatalysts such as titanium dioxide and zinc oxide, there was a problem in that the efficiency of hydrogen peroxide production was lowered as the aforementioned inorganic metal oxide-based photocatalysts decompose the produced hydrogen peroxide.

[0007] Due to these problems, research and development is being conducted on a technology to produce H2O2 through an ORR reaction using a carbon nitride (C3N4)-based organic photocatalyst, but in the case of hydrogen peroxide production using an organic photocatalyst, there was a problem of increased production costs because ethanol was required as an electron donor.

[0008] Meanwhile, polydopamine produced through the self-polymerization of dopamine precursors is known to be a potential photocatalyst for hydrogen peroxide production, but research and development on this has not been sufficiently carried out. Prior art literature

[0009] (Patent Document 0001) KR 10-2021-0147915 A(Patent Document 0002) KR 10-2023-0148763 A

[0010] Lee, Do-Yeon, et al. “Sustainable hydrogen peroxide production based on dopamine through Janus-like mechanism transition from chemical to photocatalytic reactions.” Journal of Catalysis 411 (2022): 235-244. The problem to be solved

[0011] The objective of the present invention is to solve the aforementioned problems by providing a photocatalyst for producing hydrogen peroxide using polydopamine and titanium dioxide and a method for producing the same, so that hydrogen peroxide can be produced without requiring an electron donor such as ethanol and without generating toxic by-products. means of solving the problem

[0012] A method for producing a photocatalyst for generating hydrogen peroxide using polydopamine and titanium dioxide according to one embodiment of the present invention for achieving the aforementioned purpose comprises: a step of preparing a reaction solution by mixing titanium dioxide particles, dopamine, and water; a step of adjusting the pH of the reaction solution to basic using a basic solution; a step of synthesizing a photocatalyst comprising titanium dioxide particles having a polydopamine coating layer formed on their surface by stirring the reaction solution with the adjusted pH; and a step of separating the photocatalyst from the reaction solution and washing the separated photocatalyst to produce the photocatalyst.

[0013] A photocatalyst for generating hydrogen peroxide using polydopamine and titanium dioxide according to another embodiment of the present invention for achieving the aforementioned purpose comprises titanium oxide having a polydopamine coating layer formed on its surface. Effects of the invention

[0014] The method for producing a photocatalyst for hydrogen peroxide using polydopamine and titanium dioxide according to the embodiments of the present invention with the above-described configuration has the following effects.

[0015] It is possible to provide a photocatalyst that not only does not require an electron donor such as ethanol during the production of hydrogen peroxide, but also prevents the generation of toxic byproducts and improves the efficiency of hydrogen peroxide production. Brief explanation of the drawing

[0016] FIG. 1 is a flowchart illustrating a method for manufacturing a photocatalyst for producing hydrogen peroxide using polydopamine and titanium dioxide according to one embodiment of the present invention. FIG. 2 is a conceptual diagram illustrating a method for manufacturing a photocatalyst for hydrogen peroxide production using polydopamine and titanium dioxide according to embodiments of the present invention. Figure 3 is an image showing the results of analyzing the photocatalyst prepared according to Example 1 using a scanning electron microscope according to Test Example 1. Figure 4 is an image showing the results of analyzing the photocatalyst prepared according to Example 1 using a transmission electron microscope according to Test Example 1. Figure 5 is an image showing the results of analyzing the photocatalyst prepared according to Comparative Example 3 using a scanning electron microscope according to Test Example 1. Figure 6 is an image showing the results of analyzing the photocatalyst prepared according to Comparative Example 3 using a transmission electron microscope according to Test Example 1. Figure 7 is an image showing the EDS analysis results according to Test Example 1 of the photocatalyst prepared according to Example 1. FIG. 8 is an image showing the results of analyzing photocatalysts prepared according to Examples 1 to 2 and Comparative Examples 1 to 4 using X-ray photoelectron spectroscopy according to Test Example 2. FIG. 9 is an image showing the results of analyzing the photocatalysts prepared according to Examples 1 to 2 and Comparative Examples 1 to 4 using FT-IR spectroscopy according to Test Example 2. FIG. 10 is a graph showing the results of the analysis of hydrogen peroxide production efficiency according to Test Example 3 for photocatalysts prepared according to Examples 1 to 2 and Comparative Examples 1 to 4. Figure 11 is a graph showing the results of the analysis of hydrogen peroxide production efficiency according to Test Example 3 for the photocatalyst prepared according to Example 1. Figures 12 and 13 are graphs showing the rate constant for the hydrogen peroxide generation reaction and the rate constant for the hydrogen peroxide decomposition reaction calculated according to Test Example 3. Figure 14 is a graph showing the results of measuring the amount of hydrogen peroxide produced according to Test Example 4. Figures 15 to 16 are graphs showing the results of measuring the amount of hydrogen peroxide produced according to Test Example 5. Figure 17 is a graph showing the results of the analysis of hydrogen peroxide decomposition ability according to Test Example 6. Specific details for implementing the invention

[0017] The advantages and features of the present invention, and the methods for achieving them, will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms; these embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. Meanwhile, the terms used in this specification are for describing the embodiments and are not intended to limit the present invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text.

[0019] A method for manufacturing a photocatalyst for producing hydrogen peroxide using polydopamine and titanium dioxide according to one embodiment of the present invention is a method for manufacturing a photocatalyst for producing hydrogen peroxide using polydopamine and titanium dioxide according to another embodiment of the present invention. In describing the photocatalyst for producing hydrogen peroxide using polydopamine and titanium dioxide and the method for manufacturing the same according to the embodiments of the present invention, substantially identical components are described by matching reference numerals for convenience of explanation, and repetitive descriptions are omitted.

[0021] Hereinafter, a photocatalyst for generating hydrogen peroxide using polydopamine and titanium dioxide according to embodiments of the present invention and a method for manufacturing the same will be described with reference to the drawings.

[0022] A method for producing a photocatalyst for generating hydrogen peroxide using polydopamine and titanium dioxide according to one embodiment of the present invention may include a reaction solution preparation step (S100), a pH adjustment step (S200), a synthesis step (S300), and a catalyst preparation step (S400).

[0023] A photocatalyst (10) for generating hydrogen peroxide using polydopamine and titanium dioxide according to another embodiment of the present invention may include titanium dioxide particles (11) and a polydopamine coating layer (12).

[0024] A photocatalyst (10) manufactured according to one embodiment of the present invention can act as a catalyst that enables titanium dioxide particles (11) and a polydopamine coating layer (12) to produce hydrogen peroxide when exposed to sunlight in an environment where oxygen is present.

[0026] A reaction solution is prepared by mixing 100 molar parts of titanium dioxide particles (11), 60 to 100 molar parts of a dopamine precursor, and water (S100).

[0027] The titanium dioxide particles (11) used to prepare the reaction solution in the reaction solution preparation step (S100) may be intended to form a polydopamine coating layer (12) on the surface through the synthesis step (S300) to be described later.

[0028] Titanium dioxide particles (11) can act at the beginning of the reaction when hydrogen peroxide is to be produced using a photocatalyst (10) to improve the efficiency of hydrogen peroxide production.

[0029] The size of the titanium dioxide particles (11) can be 50 to 1000 nm.

[0030] If the size of the titanium dioxide particles (11) is less than 50 nm, the titanium dioxide particles (11) are too small and clump together in the reaction solution, making it difficult to smoothly manufacture the photocatalyst (10) in the synthesis step (S300), and the amount of dopamine precursor is excessive compared to the titanium dioxide particles (11), so the polydopamine coating layer (12) may be formed too thickly.

[0031] If the size of the titanium dioxide particles (11) exceeds 1000 nm, the size of the titanium dioxide particles (11) becomes too large, so the thickness of the polydopamine coating layer (12) formed in the synthesis step (S300) becomes thin, or the polydopamine coating layer (12) is not formed uniformly over the titanium dioxide particles (11), and the activity of the photocatalyst (10) may decrease.

[0032] Preferably, the size of the titanium dioxide particles (11) can be 50 to 200 nm.

[0033] The dopamine precursor mixed with titanium dioxide particles (11) in the reaction solution preparation step (S100) may be coated on the surface of the titanium dioxide particles (11) by polymerizing in the synthesis step (S300).

[0034] The dopamine precursor mixed with titanium dioxide particles (11) in the reaction solution preparation step (S100) is not limited to any that can be polymerized into polydopamine in the synthesis step (S300), and, for example, can be dopamine hydrochloride.

[0035] If the dopamine precursor mixed with 100 moles of titanium dioxide particles (11) in the reaction solution preparation step (S100) is less than 60 moles, the thickness of the polydopamine coating layer (12) formed on the surface of the titanium dioxide particles (11) is too thin, so the photocatalyst (10) prepared according to one embodiment of the present invention may have reduced activity in the hydrogen peroxide generation reaction, and it may not be possible to prevent the hydrogen peroxide generation efficiency from decreasing as the titanium dioxide particles (11) decompose hydrogen peroxide when the hydrogen peroxide generation reaction time has elapsed.

[0036] In the reaction solution preparation step (S100), if the dopamine precursor mixed with 100 moles of titanium dioxide particles (11) exceeds 100 moles, the thickness of the polydopamine coating layer (12) becomes too thick, and when hydrogen peroxide is produced using the photocatalyst (10), light is sufficiently irradiated only onto the polydopamine coating layer (12), and light does not sufficiently reach the titanium dioxide particles (11), so the efficiency of hydrogen peroxide production may decrease.

[0038] The pH adjustment step (S200) may be a step of adjusting the pH so that the reaction solution prepared in the reaction solution preparation step (S100) becomes basic, so that a polydopamine coating layer (12) can be smoothly formed on the surface of titanium dioxide particles (11) according to the polymerization reaction of the dopamine precursor in the synthesis step (S300).

[0039] The pH adjustment step (S200) may be a step of adjusting the pH to 8.5 or higher of the reaction solution prepared in the reaction solution preparation step (S100).

[0040] If the pH of the reaction solution controlled in the pH control step (S200) is less than 8.5, the formation of a polydopamine coating layer (12) on the surface of the titanium dioxide particles (11) of the dopamine precursor may not proceed smoothly.

[0041] The upper limit for the pH of the reaction solution controlled in the pH control step (S200) is not limited, but preferably it may be less than 14. More preferably, the pH of the reaction solution controlled in the pH control step (S200) may be 10 to 12.

[0042] The basic solution used to control the reaction solution in the pH control step (S200) may be an aqueous ammonia solution.

[0044] In the pH adjustment step (S200), the reaction solution with the pH adjusted is stirred to synthesize a photocatalyst (10) containing titanium dioxide particles (11) on which a polydopamine coating layer (12) is formed on the surface.

[0045] The synthesis step (S300) may be a step of synthesizing a photocatalyst (10) by stirring for 5 minutes to 48 hours while heating the reaction solution so that the temperature of the reaction solution, whose pH was adjusted in the pH adjustment step (S200), becomes above room temperature and below 100°C. Here, the room temperature may be 25°C.

[0046] In the synthesis step (S300), the reaction solution, whose pH was adjusted in the pH adjustment step (S200), is heated from room temperature to 100°C and stirred for 5 minutes to 48 hours, so that the dopamine precursor in the reaction solution is polymerized and a polydopamine coating layer (12) can be formed on the surface of the titanium dioxide particles (11).

[0047] In the synthesis step (S300), if the temperature of the reaction solution is below room temperature, there is insufficient thermal energy for the polymerization of the dopamine precursor, so the production of the photocatalyst (10) may not proceed smoothly, and if it exceeds 100°C, side reactions may occur, so the production of the photocatalyst (10) may not proceed smoothly.

[0048] If the synthesis time in the synthesis step (S300) is less than 5 minutes, the polymerization reaction of the dopamine precursor does not occur sufficiently, so the production of the photocatalyst (10) may not be sufficiently achieved, and if it exceeds 48 hours, the polymerization reaction of the dopamine precursor occurs sufficiently, so it may not be meaningful to increase the reaction time further.

[0049] Preferably, the synthesis step (S300) may be a step of synthesizing a photocatalyst (10) by heating the reaction solution, whose pH has been adjusted in the pH adjustment step (S200), to 80 to 100°C and stirring for 2 to 4 hours.

[0050] The thickness of the polydopamine coating layer (12) formed on the surface of the titanium dioxide particles (11) in the synthesis step (S300) can be from several nanometers to several hundred nanometers, and preferably from 1 to 500 nm.

[0052] The photocatalyst (10) is separated from the reaction solution obtained in the synthesis step (S300), and the separated photocatalyst (10) is washed and dried to produce the photocatalyst (10) (S400).

[0053] In the photocatalyst manufacturing step (S400), the separation of the photocatalyst (10) from the reaction solution can generally be performed using methods for separating products from the reaction solution in the field of chemical synthesis, for example, centrifugation and vacuum filtration can be used.

[0054] In the photocatalyst manufacturing step (S400), the photocatalyst (10) separated from the reaction solution may be washed using ethanol and water, but is not limited thereto.

[0056] <Example 1>

[0057] A reaction solution was prepared by mixing 1 mmol of titanium dioxide particles (11), 0.6 mmol of dopamine precursor, and 50 ml of water.

[0058] At this time, dopamine hydrochloride (manufactured by Sigma-Aldrich) was used as the dopamine precursor. Titanium dioxide particles (11) with an average particle size of 124 nm purchased from Daejeong Chemical were used.

[0059] 0.5 mL of a 30 wt% ammonia aqueous solution was added to the prepared reaction solution to adjust the pH of the reaction solution to 11.3.

[0060] A photocatalyst (10) containing titanium dioxide particles (11) with a polydopamine coating layer (12) formed was synthesized by heating a pH-adjusted reaction solution to 90°C using an oil bath and stirring for 3 hours.

[0061] The photocatalyst (10) was separated from the reaction solution by centrifuging the reaction solution, and the photocatalyst (10) was washed twice each with deionized water and ethanol to remove impurities from the photocatalyst (10) and produce the photocatalyst (10).

[0063] <Example 2>

[0064] A photocatalyst (10) was prepared in the same manner as in Example 1, except that 1.0 mmol of dopamine precursor was mixed instead of 0.6 mmol when preparing the reaction solution.

[0066] <Comparative Example 1>

[0067] A photocatalyst (10) was prepared in the same manner as in Example 1, except that 0.1 mmol of dopamine precursor was mixed instead of 0.6 mmol when preparing the reaction solution.

[0069] <Comparative Example 2>

[0070] A photocatalyst (10) was prepared in the same manner as in Example 1, except that 0.2 mmol of dopamine precursor was mixed instead of 0.6 mmol when preparing the reaction solution.

[0072] <Comparative Example 3>

[0073] In Comparative Example 3, titanium dioxide particles (11) were used as a photocatalyst.

[0075] <Comparative Example 4>

[0076] In Comparative Example 4, polydopamine prepared using dopamine hydrochloride (manufactured by Sigma-Aldrich), a dopamine precursor, was used as a photocatalyst.

[0077] The production of polydopamine was carried out as follows.

[0078] A reaction solution was prepared by dissolving 500 mg of dopamine hydrochloride in a solvent mixture of 100 mL of deionized water (DI water) and 40 mL of ethanol. 0.6 mL of a 30 wt% aqueous ammonia solution was added to the prepared reaction solution, and the mixture was reacted at room temperature for 30 hours to polymerize polydopamine. Polydopamine was obtained from the reaction solution using a centrifuge, and the recovered polydopamine was washed twice each with DI water and ethanol to produce polydopamine.

[0080] <Test Example 1>

[0081] Test Example 1 is a test to confirm whether a polydopamine coating layer (12) has been formed. To this end, in Test Example 1, the photocatalyst (10) prepared according to Example 1 and Comparative Example 3 was analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

[0082] In addition, for the photocatalyst (10) prepared according to Example 1, EDS (Energy-dispersive X-ray spectroscopy) analysis was also performed. EDS analysis was performed to investigate the distribution of titanium, oxygen, nitrogen, and carbon.

[0083] The analysis results are shown in Figures 3 to 7.

[0084] FIG. 7 is an image showing the EDS analysis results according to Test Example 1 for each photocatalyst (10) prepared according to Example 1, and more specifically, the analysis results (7A, 7B, 7C, 7D) for titanium, oxygen, nitrogen, and carbon, respectively.

[0085] Referring to FIGS. 3 to 6, it can be seen that the particle size of the photocatalyst (10) prepared according to Example 1 is 158 nm, whereas the particle size of the photocatalyst according to Comparative Example 3 is 124 nm, which is a result that can be seen that a polydopamine coating layer (12) is formed on the surface of the titanium dioxide particles (11).

[0086] Referring to FIG. 4, it can be seen that in the case of the photocatalyst (10) prepared according to Example 1, a polydopamine coating layer (12) with a thickness of 11.44 nm is formed on the surface of titanium dioxide particles (11).

[0087] Referring to FIG. 7, it can be seen that titanium, oxygen, nitrogen, and carbon are uniformly distributed throughout the photocatalyst (10) prepared according to Example 1, and it is determined that the uniform distribution of carbon throughout is due to the polydopamine coating layer (12) being uniformly formed on the titanium dioxide particles (11).

[0089] <Test Example 2>

[0090] Test Example 2 is a test to analyze whether a polydopamine coating layer (12) is smoothly formed on the surface of titanium dioxide particles (11) and the effect of the amount of dopamine precursor mixed during the preparation of the reaction solution in the reaction solution preparation step (S100).

[0091] To this end, in Test Example 2, the photocatalysts (10) according to Examples 1 to 2 and Comparative Examples 1 to 4 were analyzed using X-ray photoelectron spectroscopy (K-alpha, Thermo Fisher Scientific) and Fourier transform infrared spectroscopy (FT-IR spectroscopy) (Nicolet iS20 FTIR, Thermo Fisher Scientific).

[0092] The analysis results are shown in Figures 8 and 9.

[0093] FIG. 8 is a graph showing the photocatalyst (10) prepared according to Examples 1 to 2 and Comparative Examples 1 to 4 analyzed by X-ray photoelectron spectroscopy. In FIG. 8, reference numerals 8A, 8B, 8C, 8D, 8E, and 8F may represent graphs for Examples 1 to 2 and Comparative Examples 1 to 4, respectively.

[0094] FIG. 9 is a graph showing the photocatalyst (10) prepared according to Examples 1 to 2 and Comparative Examples 1 to 4 analyzed by FT-IR spectroscopy. In FIG. 9, reference numerals 9A, 9B, 9C, 9D, 9E, and 9F may represent graphs for Examples 1 to 2 and Comparative Examples 1 to 4, respectively.

[0095] Referring to FIG. 8, it can be seen that characteristic peaks of polydopamine appear in the photocatalysts (10) prepared according to Examples 1 and 2 and Comparative Examples 1 and 2, and that the intensity of the characteristic peaks becomes stronger as the amount of dopamine precursor mixed during the preparation of the reaction solution increases. This is a result that can be seen that when the amount of dopamine precursor mixed during the preparation of the reaction solution increases, the polydopamine coating layer (12) is formed thickly in the synthesis step (S300).

[0096] Referring to FIG. 9, it can be seen that characteristic peaks of titanium dioxide particles (11) and polydopamine appear in the photocatalyst (10) prepared according to Examples 1 and 2 and Comparative Examples 1 and 2.

[0097] Meanwhile, the characteristic peak of polydopamine is at 3000 to 3500 cm⁻¹ due to the catechol-OH group. -1 Peaks appearing in the region, 1610 cm⁻¹ due to carbon double bond stretching modes and NH₄ bending vibrations. -1 Peak appearing in the vicinity, 1270 cm due to NH stretching vibration motion of primary amide -1 It is known that there is a peak appearing at.

[0099] <Test Example 3>

[0100] Test Example 3 is a test to confirm the hydrogen peroxide production efficiency when using photocatalysts (10) prepared according to Examples 1 to 2 and Comparative Examples 1 to 4.

[0101] Test method

[0102] In Test Example 3, each of the photocatalysts (10) for Examples 1 and 2 and Comparative Examples 1 to 4 was suspended in water at a concentration of 30 mg / L to prepare aqueous suspensions for Examples 1 and 2 and Comparative Examples 1 to 4, respectively, and hydrogen peroxide was produced by irradiating the prepared aqueous suspensions with sunlight of simulated AM 1.5G using a 150 W xenon arc lamp. Here, AM (global air mass) 1.5G is 100 mW / cm² 2 It can mean the conditions under which sunlight is irradiated.

[0103] Thermo Sientific TMThe amount of hydrogen peroxide produced was measured using the Quantitative Peroxide Assay Kit. The measurement method used was in accordance with the manufacturer's protocol. The aforementioned hydrogen peroxide production and measurement were performed independently multiple times for each of Examples 1 and 2 and Comparative Examples 1 to 4.

[0104] In addition, the amount of hydrogen peroxide produced was measured for the photocatalyst (10) for Examples 1 to 2 and Comparative Examples 1 to 4, and the rate constant for hydrogen peroxide production and the rate constant for hydrogen peroxide decomposition in Equation 1 below were calculated.

[0105] At this time, the aforementioned sunlight was irradiated onto the aqueous suspension to start the hydrogen peroxide generation reaction, and rate constants for the initial reaction (the period when 0 to 30 minutes have elapsed) and the later reaction (the period when 60 to 300 minutes have elapsed) were calculated.

[0106]

[0107] In Equation 1, [H2O2] is the hydrogen peroxide production measured at reaction time t, and K f is the rate constant for hydrogen peroxide formation, and K d ε is the rate constant for hydrogen peroxide decomposition, and t is the reaction time elapsed after the hydrogen peroxide generation reaction is initiated by irradiating an aqueous suspension with sunlight of AM 1.5G.

[0109] The measurement results for the amount of hydrogen peroxide produced according to Test Example 3 are shown in FIGS. 10 and 11 and Table 1, and the rate constants for hydrogen peroxide production and hydrogen peroxide decomposition calculated according to Test Example 3 are shown in FIGS. 12 and 13 and Table 2. FIG. 12 is a graph showing the rate constants for hydrogen peroxide production and hydrogen peroxide decomposition in the interval of 0 to 30 minutes after the start of the hydrogen peroxide production reaction, and FIG. 13 is a graph showing the rate constants for hydrogen peroxide production and hydrogen peroxide decomposition in the interval of 60 to 300 minutes after the start of the hydrogen peroxide production reaction.

[0110] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Hydrogen peroxide production amount (μmol / g) 1835.42 1387.91 221.32 414.05 311.11 1544.87

[0111] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 K f ((μmol / g) / min) Initial reaction 15.56 23.62 45.24 21.79 63.071 14.74 Reactions 4.77 3.61 5.26 1.39 0.18 5.32 K d (my -1 ) Initial reaction 0.084 0.11 0.096 0.065 0.21 0.038 Reactions 0.0017 0.0014 0.01 0.0062 0.0011 0.0010

[0112] Table 1 shows the amount of hydrogen peroxide produced after 300 minutes have elapsed since the start of the reaction. Referring to FIG. 10 and Table 1, it can be seen that when using the photocatalyst (10) prepared according to Examples 1 and 2, the amount of hydrogen peroxide produced is greater from about 120 minutes onwards than when using the photocatalyst (10) according to Comparative Examples 1 to 3, and this result confirms that the photocatalyst (10) prepared according to Examples 1 and 2 has superior activity for the hydrogen peroxide production reaction. In particular, when using the photocatalyst (10) prepared according to Example 1, it can be seen that the amount of hydrogen peroxide produced is highest at 1835.42 μmol / g for 300 minutes.

[0113] In addition, it can be confirmed that during the initial 30 minutes of hydrogen peroxide generation, the photocatalyst (10) according to Comparative Examples 1 to 3 produces a higher amount of hydrogen peroxide than the photocatalyst (10) according to Examples 1 to 2 and Comparative Example 4. This is understood to be because, in the case of the photocatalyst (10) according to Comparative Examples 1 to 3, the polydopamine coating layer (12) is thin or absent, so the titanium dioxide particles (11) mainly perform the role of a catalyst in the hydrogen peroxide generation reaction.

[0114] Referring to FIGS. 12 and 13 and Table 2, in the case of the photocatalyst (10) according to Comparative Examples 1 and 2, when the reaction time elapses from 60 to 300 minutes, K d It can be confirmed that the photocatalyst (10) according to Examples 1 and 2 is larger than the polydopamine coating layer (12), which is a result that can be confirmed that the hydrogen peroxide production efficiency decreases as reaction time progresses when the thickness of the polydopamine coating layer (12) is too thin or when the polydopamine coating layer (12) is absent.

[0115] In addition, for the photocatalyst (10) according to Comparative Example 3, K when the reaction time has elapsed from 60 to 300 minutes f It can be confirmed that the photocatalyst (10) according to Examples 1 and 2 is lower and significantly lower compared to the initial reaction time, which is a result that confirms that the hydrogen peroxide production efficiency decreases significantly as the reaction time progresses when the polydopamine coating layer (12) is not present.

[0116] In addition, for the photocatalyst (10) according to Comparative Example 4, K when the reaction time has elapsed from 0 to 30 minutes f It can be confirmed that the photocatalyst (10) according to Examples 1 and 2 is lower than that of the photocatalyst (10), which is a result that can be confirmed that the hydrogen peroxide production efficiency decreases in the early stages of the reaction when the photocatalyst (10) does not contain titanium dioxide particles (11).

[0117] In addition, when referring to FIGS. 10 to 11, it can be seen that when using the photocatalyst (10) according to Example 1, the amount of hydrogen peroxide produced continues to increase until 540 minutes of reaction time have elapsed, and this is a result that confirms that the photocatalyst (10) according to Example 1 maintains excellent activity for a long time in the hydrogen peroxide production reaction.

[0119] <Test Example 4>

[0120] Test Example 4 is a test to confirm the effect of environmental changes when generating hydrogen peroxide using the photocatalyst (10) according to Example 1.

[0121] To this end, in Test Example 4, a plurality of aqueous suspensions were prepared by suspending the photocatalyst (10) according to Example 1 in water.

[0122] Simulated sunlight (AM 1.5G, 100mW cm⁻¹) using a 150 W xenon arc lamp on the prepared aqueous suspension -2 The experiment was conducted by irradiating the prepared aqueous suspension to generate hydrogen peroxide, with experimental group 1 using no electron donor, experimental group 2 using ethanol as the electron donor, and experimental group 3 carrying out the hydrogen peroxide reaction in a nitrogen-saturated environment. In addition, experimental group 4 was defined as not irradiating the prepared aqueous suspension with the aforementioned sunlight. For experimental group 2, a 10 vol% ethanol solution was used as the electron donor, and for experimental group 3, nitrogen was purged into the aqueous suspension for more than 30 minutes to create a nitrogen-saturated environment, and the amount of hydrogen peroxide produced was measured while continuously purging the aqueous suspension with nitrogen even when irradiating with the aforementioned sunlight.

[0123] Tests for each experimental group were conducted independently, and the measurement of hydrogen peroxide production for each group was performed by Thermo Scientific TMThe amount of hydrogen peroxide produced was measured using the Quantitative Peroxide Assay Kit. The measurement method followed the manufacturer's protocol.

[0124] The measurement results are shown in Fig. 14.

[0125] Figure 14 is a graph showing the results of measuring the amount of hydrogen peroxide produced according to each of experimental groups 1 to 4.

[0126] Referring to FIG. 14, it can be seen that hydrogen peroxide is sufficiently produced even without using ethanol as an electron donor, and that hydrogen peroxide is not produced smoothly when using a photocatalyst (10) if there is no oxygen in the atmosphere or if sunlight is not irradiated.

[0128] <Test Example 5>

[0129] Test Example 5 is a test to confirm the stability of the photocatalyst (10).

[0130] To this end, in Test Example 5, a photocatalyst (10) according to Example 1 according to Example 1 was suspended in water to prepare a plurality of aqueous suspensions with a concentration of 30 mg / L.

[0131] To this end, two experiments were performed in Test Example 5.

[0132] Experiment 1

[0133] Simulated sunlight (AM 1.5G, 100mW cm⁻¹) using a 150 W xenon arc lamp on the prepared aqueous suspension -2 Hydrogen peroxide was produced by irradiating the sample, and the amount of hydrogen peroxide produced was measured while conducting the experiment by repeating the process of irradiating the sample with sunlight for 3 hours followed by not irradiating it with sunlight for 3 hours several times.

[0134] Experiment 2

[0135] Simulated sunlight (AM 1.5G, 100mW cm⁻¹) using a 150 W xenon arc lamp on the prepared aqueous suspension -2 The amount of hydrogen peroxide produced was measured while investigating for 120 minutes.

[0136] Afterward, the photocatalyst (10) was recovered and washed from the aqueous suspension, and the washed photocatalyst (10) was suspended in water to produce an aqueous suspension with a concentration of 30 mg / L. Then, the amount of hydrogen peroxide produced was measured by repeating the process of irradiating the prepared aqueous suspension with the aforementioned sunlight for 120 minutes five times.

[0138] Each experiment was conducted independently, and the amount of hydrogen peroxide produced was measured by Thermo Scientific TM The amount of hydrogen peroxide produced was measured using the Quantitative Peroxide Assay Kit. The measurement method followed the manufacturer's protocol.

[0140] The measurement results are shown in Figures 15 and 16.

[0141] Referring to FIG. 15, it can be seen that when simulated sunlight using a 150 W xenon arc lamp is irradiated onto an aqueous suspension, the amount of hydrogen peroxide produced increases, and when sunlight is not irradiated, the increase in the amount of hydrogen peroxide produced does not occur smoothly. In addition, it can be seen that when sunlight is irradiated again after not irradiating for 3 hours, the amount of hydrogen peroxide produced increases. This is a result that confirms that hydrogen peroxide is produced even when the hydrogen peroxide production reaction is performed discontinuously when using the photocatalyst (10) prepared according to one embodiment of the present invention, and it is a result that confirms the excellent stability of the photocatalyst (10).

[0142] In addition, referring to FIG. 16, it can be seen that hydrogen peroxide is produced smoothly even when the hydrogen peroxide production experiment is repeated 6 times using the photocatalyst (10) prepared according to Example 1, and this is a result that confirms the excellent stability of the photocatalyst (10) prepared according to one embodiment of the present invention.

[0144] <Test Example 6>

[0145] In Test Example 6, the hydrogen peroxide decomposition ability of the photocatalyst (10) prepared according to Examples 1 to 2 and Comparative Examples 1 to 3 was analyzed. The analysis method was performed as follows.

[0146] To this end, in Test Example 6, a photocatalyst (10) was dispersed in a 100 μM solution, and then nitrogen was purged into the solution for 30 minutes. Subsequently, while purging the solution with nitrogen, simulated sunlight (AM 1.5G, 100 mW cm²) was applied using a 150 W xenon arc lamp. -2 The hydrogen peroxide concentration of the solution was measured while investigating. The ratio of the hydrogen peroxide concentration (C / CO) to the initial hydrogen peroxide concentration at each reaction time (Time(min)) was calculated.

[0147] The above analysis was performed independently for each of the photocatalysts (10) prepared according to Examples 1 to 2 and Comparative Examples 1 to 3.

[0148] The analysis results are shown in Figure 17 and Table 3.

[0149] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Hydrogen peroxide concentration (μM) after 120 minutes of reaction time 100 100 30.93 51.16 14.90 Ratio of hydrogen peroxide concentration after a reaction time of 120 minutes to initial hydrogen peroxide concentration (C / C 0) 1 1 0.31 0.51 0.15

[0150] Referring to FIG. 17 and Table 3, it can be seen that in the case of the photocatalyst (10) prepared according to Example 1 and Example 2, the concentration of hydrogen peroxide in the solution is maintained, whereas in the case of the photocatalyst (10) prepared according to Comparative Examples 1 to 3, the concentration of hydrogen peroxide decreases as hydrogen peroxide is decomposed. This result confirms that hydrogen peroxide is decomposed by titanium dioxide particles (11) when the thickness of the polydopamine coating layer (12) is too thin or when the polydopamine coating layer (12) is absent.

[0151] In particular, in the case of the photocatalyst (10) prepared according to Comparative Example 3, it can be seen that the hydrogen peroxide in the solution decreased by 85.1% compared to the beginning of the reaction.

[0153] A person skilled in the art to which the invention pertains will understand that the present invention may be implemented in other specific forms without altering its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the claims and their equivalents should be interpreted as being included within the scope of the present invention. Explanation of the symbols

[0154] 10: Photocatalyst, 11: Titanium dioxide particles, 12: Polydopamine coating layer, S100: Reaction solution preparation step, S200: pH adjustment step, S300: Synthesis step, S400: Catalyst manufacturing step.

Claims

Claim 1 A step of preparing a reaction solution by mixing 100 molar parts of titanium dioxide particles, 60 to 100 molar parts of dopamine, and water; a step of adjusting the pH of the reaction solution to 10 to 12 using a basic solution; and a step of synthesizing a photocatalyst comprising titanium dioxide particles having a polydopamine coating layer formed on their surface by stirring the pH-adjusted reaction solution at 80°C to 100°C for 2 to 4 hours. A method for manufacturing a photocatalyst for producing hydrogen peroxide using polydopamine and titanium dioxide, comprising the step of separating the photocatalyst from the reaction solution and washing the separated photocatalyst to produce the photocatalyst; wherein the photocatalyst exhibits a hydrogen peroxide production amount of 1300 μmol / g or more after 300 minutes under simulated sunlight (AM 1.5G) irradiation conditions, and has the characteristic that the hydrogen peroxide concentration at the time of 120 minutes of reaction time is maintained without decreasing compared to the initial concentration. Claim 2 delete Claim 3 A method for producing a photocatalyst for generating hydrogen peroxide using polydopamine and titanium dioxide, wherein, in claim 1, the step of preparing the reaction solution is to prepare the reaction solution by mixing the titanium dioxide particles having a particle size of 50 to 1000 nm, and the step of synthesizing the catalyst is to synthesize a catalyst comprising the titanium dioxide particles having a polydopamine coating layer formed on the surface having a thickness of 10 to 50 nm. Claim 4 delete Claim 5 A photocatalyst for producing hydrogen peroxide using polydopamine and titanium dioxide, wherein a polydopamine coating layer with a thickness of 10 to 50 nm is formed on the surface of titanium dioxide particles, formed at a ratio of 60 to 100 molar parts of dopamine to 100 molar parts of titanium dioxide particles, exhibits a hydrogen peroxide production amount of 1300 μmol / g or more after 300 minutes under simulated sunlight (AM 1.5G) irradiation conditions, and has the characteristic that the hydrogen peroxide concentration at the time of 120 minutes of reaction time is maintained without decreasing compared to the initial concentration.

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