Copper(i) oxide subparticle-based photocatalyst for hydrogen peroxide generation and method for manufacturing the same

Abstract

The present invention relates to a photocatalyst for hydrogen peroxide production based on copper(I) oxide superparticles and a method for producing the same, and more specifically, to a photocatalyst and a method for producing the same that stably and efficiently produces hydrogen peroxide without a sacrificial agent by forming a polydopamine coating layer on the surface of copper(I) oxide superparticles. The present invention comprises a photocatalyst comprising copper(I) oxide superparticles; and polydopamine formed on the surface of the copper(I) oxide superparticles; wherein the copper(I) oxide superparticle-based hydrogen peroxide generating photocatalyst is characterized by generating hydrogen peroxide without the addition of a sacrificial agent, and The technical gist of the invention is a method for producing a hydrogen peroxide-generating photocatalyst based on copper(I) oxide superparticles, comprising the steps of: preparing a copper(I) oxide synthesis solution; stirring the synthesis solution to form copper(I) oxide superparticles; adding dopamine to the synthesis solution in which the copper(I) oxide superparticles are formed; and self-polymerizing the dopamine under alkaline conditions to coat the surface of the copper(I) oxide superparticles with polydopamine.

Description

Technology Field

[0001] The present invention relates to photocatalytic technology, and more specifically, to a photocatalyst and a method for manufacturing the same that improves the stability of a metal oxide-based photocatalyst to enable the production of hydrogen peroxide without a sacrificial agent. Background Technology

[0002] In general, hydrogen peroxide (H2O2) is used as an important oxidizing agent in various fields such as chemical synthesis, environmental purification, medical and industrial processes.

[0003] Conventionally, large-scale production was carried out through chemical methods such as the anthraquinone process, but there were problems such as process complexity, high energy consumption, and environmental pollution.

[0004] Accordingly, photocatalyst-based hydrogen peroxide generation technology utilizing sunlight is attracting attention. However, conventionally known metal oxide photocatalysts have limited efficiency and stability due to their vulnerability to photodecomposition and the side effect of simultaneously decomposing the generated hydrogen peroxide. Furthermore, they had limitations in that they were not environmentally friendly, as additives such as alcohol-based sacrificial agents were required to maintain a high-efficiency reaction.

[0005] In particular, copper(I) oxide (Cu2O) is attracting attention as a promising photocatalytic material due to its excellent ability to absorb visible light, but there have been limitations in its actual application due to instability caused by oxidation and the problem of promoting hydrogen peroxide decomposition. Therefore, there is a need for the development of a new technology that can improve stability while maintaining the photocatalytic performance of copper(I) oxide. Prior art literature

[0006] Republic of Korea Published Patent Application No. 10-2025-0101426, published July 4, 2025. Republic of Korea Published Patent Application No. 10-2024-0154207, published October 25, 2024. The problem to be solved

[0007] The present invention was developed to resolve the aforementioned problems, and aims to provide a photocatalyst and a method for manufacturing the same that improve the problem of reduced efficiency caused by the decomposition of the photocatalyst itself and the decomposition of the generated hydrogen peroxide in photocatalyst-based hydrogen peroxide production, and enable stable and efficient hydrogen peroxide production without additives such as sacrificial agents.

[0008] In addition, another objective is to provide a technology that minimizes performance degradation even under conditions of prolonged light irradiation and repeated use, while ensuring high reproducibility and durability.

[0009] The objectives of the present invention are not limited to those mentioned above, and other unmentioned objectives may be clearly understood from the descriptions below and may be sufficiently included in the objectives of the present invention. means of solving the problem

[0010] A hydrogen peroxide generating photocatalyst based on copper(I) oxide supraparticles according to one aspect of the present invention for achieving the above objective may be composed of copper(I) oxide supraparticles and polydopamine (PDA) formed on the surface thereof.

[0011] In addition, a method for manufacturing a hydrogen peroxide-generating photocatalyst based on copper(I) oxide superparticles according to another aspect of the present invention for achieving the above objective may comprise the steps of: preparing a copper(I) oxide synthesis solution; stirring the synthesis solution to form copper(I) oxide superparticles; adding dopamine to the synthesis solution in which copper(I) oxide superparticles are formed; and self-polymerizing dopamine under alkaline conditions to coat polydopamine on the surface of the copper(I) oxide superparticles. Effects of the invention

[0012] The copper(I) oxide superparticle-based photocatalyst for hydrogen peroxide generation and the method for manufacturing the same according to the present invention, based on the above-described configuration, are environmentally friendly as they can generate hydrogen peroxide in a high yield without adding a sacrificial agent. In addition, the photodegradation of copper(I) oxide and the decomposition of hydrogen peroxide are suppressed through polydopamine coating, thereby improving stability, and they provide excellent durability by maintaining more than 95% of their initial performance even after repeated light irradiation and reuse.

[0013] In addition, it has high activity producing at least 1860 μmol / g of hydrogen peroxide in a 5-hour reaction and exhibits improved efficiency and selectivity compared to copper(I) oxide or polydopamine-only catalysts.

[0014] Therefore, the present invention can be commercialized as an eco-friendly and stable hydrogen peroxide production technology in various fields such as environmental purification, chemical synthesis, and industrial oxidation processes. Brief explanation of the drawing

[0015] FIG. 1 is a diagram showing SEM images and particle diameter distributions of an example and a comparative example according to one embodiment of the present invention. FIG. 2 is a figure showing the EDS mapping results of Example 2 and Comparative Example 1 according to one embodiment of the present invention, illustrating the distribution of Cu, O, C, and N elements. Figure 3 is a graph showing the UV-Vis absorption spectra of an example and a comparative example according to one embodiment of the present invention. Figure 4 is a graph showing the FT-IR analysis results of an example and a comparative example according to one embodiment of the present invention. Figure 5 is a graph showing the XPS analysis results of an example and a comparative example according to one embodiment of the present invention. FIG. 6 is a diagram showing a TGA analysis curve according to one embodiment of the present invention and the TEM image and EDX mapping results of Example 2. FIG. 7 is a graph showing a comparison of the amount of hydrogen peroxide (H2O2) produced (top) and an evaluation of reaction conditions / stability (bottom) of an example and a comparative example according to one embodiment of the present invention. FIG. 8 is a graph showing the amount of H2O2 produced under light on / off conditions of Example 2 according to one embodiment of the present invention. FIG. 9 is a graph showing the results of the reusability evaluation of Example 2 according to one embodiment of the present invention. FIG. 10 is a graph showing the PL spectra (left) and EIS Nyquist plot (right) of Comparative Examples 1 and 2 and Example 2 according to one embodiment of the present invention. FIG. 11 is a graph showing the Mott-Schottky analysis results of Comparative Examples 1 and 2 and Example 2 according to one embodiment of the present invention. FIG. 12 is a graph showing the optical bandgap calculation results through the Tauc plot of Comparative Examples 1 and 2 and Example 2 according to one embodiment of the present invention. FIG. 13 is a diagram showing a schematic diagram of band alignment of Comparative Example 1 and Comparative Example 2 according to one embodiment of the present invention. Figure 14 is a graph showing the experimental results of a radical scavenger of Example 2 according to one embodiment of the present invention. FIG. 15 is a diagram showing XPS-based valence band analysis results (top) and a schematic diagram of energy band alignment before and after contact to explain the photocatalytic reaction mechanism of the present invention. FIG. 16 is a flowchart illustrating the sequence of a method (S10) for manufacturing a hydrogen peroxide-generating photocatalyst based on copper (I) oxide superparticles according to another embodiment of the present invention. Specific details for implementing the invention

[0016] The present invention relates to a photocatalyst for hydrogen peroxide generation based on copper(I) oxide superparticles and a method for manufacturing the same.

[0017] In particular, the photocatalyst according to the present invention is characterized by the fact that it enables stable and efficient production of hydrogen peroxide (H2O2) without the addition of a sacrificial agent by forming polydopamine (PDA) on the surface of copper (I) oxide superparticles.

[0019] Hereinafter, a photocatalyst for hydrogen peroxide generation based on copper(I) oxide superparticles and a method for manufacturing the same according to a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0021] A photocatalyst (10) according to one embodiment of the present invention may be composed of copper (I) oxide superparticles (100) and polydopamine (200) formed on the surface thereof.

[0023] In the present invention, 'copper(I) oxide (Cu2O)' is commonly referred to as 'copper(I) oxide' and is a semiconductor material having excellent light absorption characteristics in the visible light region. For convenience, it may be referred to as 'Cu2O' below, and 'copper(I) oxide superparticles' are also referred to as 'Cu2O superparticles'.

[0024] In this specification, the term 'supraparticle' refers to an aggregate structure formed by the self-assembly of a plurality of primary nanoparticles.

[0026] In addition, the term 'polydopamine (200)' in this specification refers to a polydopamine layer formed on the surface of a copper (I) oxide superparticle, as indicated by reference numeral 200 in the drawings. At this time, 'polydopamine shell,' 'polydopamine coating layer,' 'polydopamine layer,' etc., all refer to the same concept and mean a structure in which self-polymerized polydopamine is formed on the surface of a copper (I) oxide superparticle. Therefore, even if these terms are used interchangeably for convenience below, they should be understood as having the same meaning.

[0027] On the other hand, if it is simply labeled as 'polydopamine,' it should be understood to refer to a polydopamine substance synthesized independently, such as in Comparative Example 2, or polydopamine present in a synthesis solution.

[0029] In addition, 'H2O2' in this specification means 'hydrogen peroxide'. For convenience, even if 'H2O2' is written in experimental examples and drawings to maintain consistency with data notation, it should be understood that this refers to hydrogen peroxide.

[0031] The photocatalyst (10) according to the present invention may have a core-shell structure in which a copper (I) oxide superparticle (100) forms the core and a polydopamine (200) forms the shell on the surface.

[0032] At this time, the average thickness of the polydopamine (200) is 1 to 3 nm, and the mass percentage may be 2.0 to 8.0 wt%.

[0033] If the thickness of the polydopamine (200) is less than 1 nm, the coating layer is not sufficiently developed, so the photo-corrosion inhibition and electron-hole recombination inhibition effects are insufficient. Conversely, if it exceeds 3 nm, the excessive polymer layer blocks the transmission path and impairs light absorption efficiency, causing the hydrogen peroxide generation efficiency to drop sharply.

[0034] In addition, if the mass percentage of polydopamine (200) is less than 2 wt%, the effect of inhibiting hydrogen peroxide decomposition is insufficient due to the non-uniform coating, and if it exceeds 8 wt%, the photocatalytic activity is reduced due to the thick layer. Therefore, the above range is a condition that can simultaneously secure charge separation and stability. More preferably, the mass percentage of polydopamine (200) may be 4 to 8 wt%.

[0036] Polydopamine (200) satisfying the above thickness and mass percentage range can be formed on the surface of copper (I) oxide superparticles (100) by self-polymerizing dopamine at a concentration of 2 to 8 mg / mL in an alkaline solution containing copper (I) oxide superparticles.

[0037] If the dopamine concentration is less than 2 mg / mL, the coating layer is excessively thin and lacks stability, and if it exceeds 8 mg / mL, excess polydopamine (200) is formed, causing aggregation between adjacent superparticles (100). This aggregation increases the particle diameter, thereby reducing the specific surface area, and interferes with the electron transfer pathway from the Cu2O conduction band to the PDA conduction band in energy band alignment, thereby hindering the selective two-electron oxygen reduction reaction (2e - It can have an adverse effect on the ORR) path.

[0039] The photocatalyst (10) according to the present invention can produce at least 1860 μmol / g of hydrogen peroxide when irradiated with light for 5 hours.

[0040] In this case, the light source used for light irradiation may be an artificial light source that simulates sunlight conditions.

[0041] In addition, during the process of repeating the on / off of an artificial light source simulating sunlight conditions at a predetermined cycle, the amount of hydrogen peroxide produced can be maintained or increased for at least 21 hours.

[0042] As a result of confirming the reusability of the photocatalyst (10), even if the process of recovering and reusing the photocatalyst (10) after performing the hydrogen peroxide generation reaction with the artificial light source on is repeated at least 4 times, more than 95% of the initial hydrogen peroxide generation performance is maintained.

[0043] At this time, a centrifuge or the like can be used as a method to recover the photocatalyst (10).

[0045] In addition, the photocatalyst (10) according to the present invention may have an average diameter in the range of 200 to 2200 nm. If the diameter is less than 200 nm, the structural stability of the particles is low, making them prone to decomposition and dissolution during the reaction. Conversely, if the diameter exceeds 2200 nm, interfacial charge separation is limited due to aggregation, and the light absorption efficiency required for hydrogen peroxide production is reduced. Therefore, within the range of 200 to 2200 nm, the stability of the particles, specific surface area, and charge transport path are balanced, thereby optimizing the photocatalytic activity.

[0047] A method (S10) for manufacturing a photocatalyst for generating hydrogen peroxide based on copper(I) oxide superparticles according to another embodiment of the present invention may include the steps of preparing a copper(I) oxide synthesis solution (S100), stirring the synthesis solution to form copper(I) oxide superparticles (S300), adding dopamine to the synthesis solution in which copper(I) oxide superparticles are formed (S500), and self-polymerizing dopamine under alkaline conditions to coat polydopamine on the surface of the copper(I) oxide superparticles (S700).

[0049] First, the step (S100) of preparing a copper(I) oxide synthesis solution is to prepare a synthesis solution containing copper acetate monohydrate (Cu(OAc)2·H2O) and L-ascorbic acid.

[0050] More specifically, a synthesis solution can be obtained by dissolving copper acetate monohydrate in deionized water and adding L-ascorbic acid.

[0052] Next, the step (S300) of forming copper (I) oxide superparticles is to form copper (I) oxide superparticles (100) in the synthesis solution through a reduction reaction carried out by stirring the synthesis solution.

[0054] Subsequently, the step of adding dopamine (S500) involves adding dopamine hydrochloride to a synthesis solution containing formed copper (I) oxide superparticles at a concentration of 2 to 8 mg / mL, more preferably 4 to 8 mg / mL.

[0056] Finally, the step (S700) of coating polydopamine on the surface of the copper (I) oxide superparticles is to form polydopamine (200) on the surface of the copper (I) oxide superparticles (100) by maintaining the synthesis solution under alkaline conditions to self-polymerize dopamine.

[0057] More specifically, during the process of stirring a synthetic solution containing copper (I) oxide superparticles (100) and dopamine, an aqueous ammonia solution with a concentration of 25 to 30 percent is added to induce self-polymerization of dopamine, so that polydopamine (200) can be uniformly coated.

[0059] The copper (I) oxide superparticles (100) or photocatalyst (10) generated in the above process can be recovered in powder form through a conventional method (e.g., centrifugation), and the recovered sample can be provided for evaluation of a single sample (Comparative Example 1) or used in subsequent experiments such as confirming reusability.

[0061] Example 1. Preparation of photocatalyst (10) under conditions of dopamine concentration of 2 mg / mL

[0062] A synthesis solution was prepared by dissolving 1 g of copper acetate monohydrate in 50 mL of deionized water, adding 1 g of L-ascorbic acid, and stirring for 5 minutes. As the prepared synthesis solution was continuously stirred, copper (I) oxide superparticles (100) were formed.

[0064] Subsequently, dopamine hydrochloride was added at a concentration of 2 mg / mL to the synthesis solution in which copper (I) oxide superparticles (100) were formed. Then, 0.6 mL of an aqueous ammonia solution with a concentration of 25-30% was added to create alkaline conditions, and stirring was maintained to induce a self-polymerization reaction of dopamine.

[0065] As a result, a copper(I) oxide / polydopamine composite (hereinafter referred to as 'photocatalyst (10)') was obtained in which polydopamine (200) with a thickness of about 1 nm and a mass percentage of about 2.0 wt% was coated on the surface of copper(I) oxide superparticles (100). The generated photocatalyst (10) was centrifuged (10,000 rpm, 10 minutes), washed twice each with deionized water and ethanol, and then dried in a desiccator to be recovered in powder form.

[0067] Example 2. Preparation of photocatalyst (10) under conditions of dopamine concentration of 4 mg / mL

[0068] The procedure was carried out in the same manner as in Example 1, but dopamine hydrochloride was added at a concentration of 4 mg / mL.

[0069] As a result, a photocatalyst (10) was obtained in which polydopamine (200) with an average thickness of about 1.5 nm and a mass percentage of about 4.0 wt% was uniformly coated on the surface of copper (I) oxide superparticles (100).

[0071] Example 3. Preparation of photocatalyst (10) under conditions of dopamine concentration of 6 mg / mL

[0072] The procedure was carried out in the same manner as in Example 1, but dopamine hydrochloride was added at a concentration of 6 mg / mL.

[0073] As a result, a photocatalyst (10) was obtained in which a polydopamine (200) layer with a thickness of about 2 nm and a mass percentage of about 6.0 wt% was formed on the surface of copper (I) oxide superparticles (100).

[0075] Example 4. Preparation of photocatalyst (10) under conditions of dopamine concentration of 8 mg / mL

[0076] The procedure was carried out in the same manner as in Example 1, but dopamine hydrochloride was added at a concentration of 8 mg / mL.

[0077] As a result, a layer of polydopamine (200) with a thickness of about 3 nm and a mass percentage of about 8.0 wt% or more was formed on the surface of the copper (I) oxide superparticle (100), and aggregation between some superparticles (100) was observed.

[0079] Comparative Example 1. Copper(I) oxide superparticles

[0080] 1 g of copper acetate monohydrate was dissolved in 50 mL of deionized water, and then 1 g of L-ascorbic acid was added and stirred for 5 minutes. The synthesis solution was centrifuged (10,000 rpm, 10 minutes), washed twice each with deionized water and ethanol, and dried in a desiccator to obtain copper(I) oxide superparticles in powder form.

[0081] The copper(I) oxide superparticle of Comparative Example 1 is the same material as the copper(I) oxide superparticle shown as (100) in the example.

[0083] Comparative Example 2. Polydopamine

[0084] Dopamine was dissolved at a concentration of 4 mg / mL under conditions where copper(I) oxide superparticles were not present, and then an aqueous ammonia solution with a concentration of 25-30% was added to create alkaline conditions and induce a self-polymerization reaction. After the reaction was completed, the product was centrifuged, washed, and dried to obtain polydopamine powder. This is an independent polydopamine sample that is not combined with copper(I) oxide superparticles, and accordingly, this comparative example is clearly distinguished from the core-shell structure of the example in which polydopamine (200) is coated on the surface of copper(I) oxide superparticles.

[0086] Comparative Example 3. Copper(I) oxide superparticles / polydopamine simple mixture

[0087] A Cu2O / PDA mixed sample was prepared by simply mixing copper(I) oxide superparticle powder synthesized by the method of Comparative Example 1 and polydopamine powder obtained by the method of Comparative Example 2 without a separate coating process. This comparative example is clearly distinguished from the core-shell structure of the example as a simple mixture in which no polydopamine layer is formed on the surface of the copper(I) oxide superparticles and the two components exist independently.

[0089] <Experimental Example 1> Morphological and Structural Analysis

[0090] Samples obtained from Examples 1 to 4 and Comparative Example 1 (Cu2O superparticles) and Comparative Example 2 (polydopamine) were observed using a scanning electron microscope (SEM, JSM-6700F, JEOL) to analyze their morphology and structure, and the results are shown in Figure 1.

[0091] Referring to Fig. 1, Comparative Example 1 (Cu2O superparticles) was in the form of a spherical aggregate with an average diameter of 270±83 nm, and Comparative Example 2 (polydopamine) was in the form of a spherical aggregate with an average diameter of 411±94 nm.

[0092] Meanwhile, the photocatalyst (10) of Examples 1 to 4 had a structure in which polydopamine (200) was uniformly coated on the surface of copper (I) oxide superparticles (100), and the average diameters were 275±77, 318±85, 367±60, and 2107±396 nm, respectively, and it was confirmed that the coating thickness gradually increased as the dopamine concentration increased.

[0094] The results of energy dispersive X-ray spectroscopy (EDS) mapping analysis based on SEM images are shown in Figure 2.

[0095] Referring to FIG. 2, in the case of Example 2, it was observed that copper (Cu) and oxygen (O) are uniformly distributed throughout, and nitrogen (N) and carbon (C) also demonstrate the presence of polydopamine (200) successfully coated on the surface of copper (I) oxide superparticles (100).

[0096] On the other hand, in Comparative Example 1 (Cu2O superparticle), carbon (C) and nitrogen (N) components are not detected, clearly showing the difference in whether polydopamine (200) is coated on the surface of the copper (I) oxide superparticle (100) only through the synthesis process.

[0098] In addition, to monitor the polydopamine (200) coating process on the surface of the copper (I) oxide superparticle (100), the spectrum was analyzed using ultraviolet-visible (UV-Vis) spectroscopy, and the absorbance at a wavelength of 200 nm was normalized to 1 to clarify the comparison of relative content. The results are shown in FIG. 3.

[0100] As confirmed by the normalized spectrum, in Examples 1 to 4, as the dopamine concentration increased, the characteristic absorption peak (498 nm) of the copper (I) oxide superparticle (100) gradually decreased, and in Example 4, it was weakened to the point where it was not clearly distinguishable compared to other conditions.

[0101] Instead, a broad absorption band characteristic of polydopamine (200) was prominently displayed across the entire visible light range, and the total absorbance also gradually increased with increasing dopamine concentration.

[0102] This supports the fact that the more dopamine added, the thicker the polydopamine (200) layer formed on the surface of the copper (I) oxide superparticle (100) becomes.

[0104] In addition, looking at the results of the comparative examples, Comparative Example 1 (Cu2O superparticle) clearly maintained a characteristic peak around 498 nm, whereas Comparative Example 2 (polydopamine) did not show the corresponding peak and a broad absorption band was confirmed across the entire visible light range.

[0105] This clearly demonstrates that the spectral change observed in Examples 1 to 4 is not due to simple mixing, but is the result of the actual formation of a polydopamine (200) layer on the surface of the copper (I) oxide superparticle (100).

[0107] <Experimental Example 2> Analysis of Composition and Chemical Properties

[0108] FT-IR (IR-6000, Shimadzu), XPS (K-Alpha, Thermo Fisher Scientific), and TGA (Q50, TA Instruments) analyses were performed on samples of Examples 1 to 4 and Comparative Example 1 (Cu2O superparticles) and Comparative Example 2 (polydopamine), and the results are shown in Figures 4 to 6.

[0110] First, according to the FT-IR analysis results (Fig. 4), in the case of Comparative Example 1 (Cu2O superparticles), 1380 cm⁻¹ -1 A distinct peak corresponding to the Cu-O stretching vibration was observed in the vicinity, and the intensity of this peak gradually decreased as the dopamine concentration increased from Examples 1 to 4. On the other hand, characteristic peaks attributed to polydopamine were identified, ranging from 3200 to 3500 cm⁻¹. -1 The broad band of the region is the catechol OH group, 1590 cm⁻¹ -1 NH bending vibration, 1490cm -1 C=C stretching vibration, 1260cm -1 These corresponded to the CO stretching vibrations. These polydopamine peaks gradually intensified as the dopamine concentration increased, which supports the successful formation of a polydopamine (200) layer on the surface of the copper (I) oxide superparticle (100).

[0112] Next, the elemental composition and chemical bonding state of the sample surface were confirmed through XPS analysis (Fig. 5). In Comparative Example 1 (Cu2O superparticles), no N 1s peak appeared at all, but in Examples 1 to 4, a weak but consistent N 1s signal was detected, suggesting that a polydopamine (200) layer was introduced. Conversely, in Comparative Example 2 (polydopamine), which is a polydopamine-only sample, no Cu 2p peak appeared, which means that no copper component was present. Therefore, it can be confirmed that, unlike in the case of the examples, a complex between the two components was not formed.

[0113] In particular, the high-resolution Cu 2p spectrum observed in Example 2 showed a tendency to shift toward a relatively higher binding energy compared to Comparative Example 1 (Cu2O superparticle), which means that electron transfer occurred from the copper (I) oxide superparticle (100) to the polydopamine (200) layer.

[0114] In addition, in the C 1s spectrum, in Comparative Example 2 (polydopamine), which is a polydopamine-only sample, only the CC (258.2 eV) and CN / CO (287.3 eV) peaks were present, whereas in Example 2, a new C=O peak appeared at approximately 288.8 eV. This indicates that the catechol group of polydopamine (200) was converted into a carbonyl group as it was oxidized, and shows that a structural change occurred during the process of polydopamine (200) forming a stable chemical bond on the surface of the copper (I) oxide superparticle (100).

[0116] Next, in the TGA (thermogravimetric analysis) (top left of FIG. 6), the following formula was used to calculate the quantitative content of polydopamine (200).

[0117]

[0118] Here is the residual mass percentage (wt%) of Comparative Example 1 (Cu2O superparticles), is the residual mass percentage (wt%) of Comparative Example 2 (polydopamine), Each represents the residual mass percentage (wt%) of the composite (photocatalyst (10)) formed according to the method for manufacturing the photocatalyst (10) of the present invention, and represents the mass percentage (wt%) of polydopamine (200) in the complex (photocatalyst (10)).

[0120] As a result of the analysis, the mass percentage of polydopamine (200) in the composite in Example 2 was calculated to be approximately 3.85 wt%, which is consistent with the dopamine concentration (4.0 wt%) added during synthesis. These results quantitatively demonstrate that polydopamine (200) was stably introduced onto the surface of the copper (I) oxide superparticle (100) to form a uniform coating layer. Additionally, in Comparative Example 1 (Cu2O superparticle), a maximum mass increase of 105% was observed at around 220°C, which is interpreted as the result of oxidation proceeding during the thermal analysis process and the transition of the Cu2O phase to the CuO phase. A similar phase transition phenomenon was observed in Example 2 as well, suggesting that Cu2O can be oxidized even in the presence of a polydopamine (200) coating layer.

[0122] Additionally, the structure of the copper(I) oxide superparticle (100) of Example 2 and the polydopamine (200) coating layer were directly observed through TEM analysis (upper right of FIG. 6). In the case of Example 2, the thickness of the polydopamine (200) layer was measured to be approximately 1.58 ± 0.5 nm on average, and it was confirmed to be a thin coating layer that is continuously and uniformly distributed along the surface of the copper(I) oxide superparticle (100). This suggests that the polydopamine (200) is not simply adsorbed, but is a core-shell structure formed by stable polymerization and growth on the surface of the copper(I) oxide superparticle (100).

[0124] Furthermore, in the TEM-EDX mapping results of Example 2 (bottom of FIG. 6), a clear elemental separation phenomenon was confirmed in which Cu and O were concentrated in the center (core) of the particle, and C and N were distributed in the outer (shell). These results demonstrate that polydopamine (200) was uniformly coated on the surface of the copper (I) oxide superparticle (100), forming a distinct and continuous core-shell structure.

[0126] In summary, TGA analysis demonstrated that the quantitative content of polydopamine (200) corresponds well to the dopamine concentration, and TEM and EDX analysis clearly confirmed that the polydopamine (200) layer is uniformly introduced onto the surface of the copper (I) oxide superparticle (100) to form a core-shell structure. This supports the fact that the composite of the present invention is manufactured in a structurally and chemically stable form.

[0128] <Experimental Example 3> Evaluation of Photocatalyst Performance (Amount of Hydrogen Peroxide Produced)

[0129] The photocatalytic performance of the samples prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was evaluated. A 150W xenon arc lamp was used as the light source, and the reaction was carried out by adding 30 mg·L of the sample to 100 mL of oxygen-saturated deionized water. -1 The procedure was performed with the solution dispersed at a specific concentration. The concentration of the generated hydrogen peroxide (H2O2) was quantified using a Peroxide Assay Kit. The results are shown in Figures 7 to 9.

[0131] First, as shown in the data located at the top of Fig. 7, Examples 1 to 4 all exhibited improved photocatalytic activity compared to Comparative Examples 1 to 3. In particular, Example 2 showed approximately 2766 μmol·g at 5 hours of irradiation. -1 H2O2 was produced, which is Example 1 (375 μmol·g -1 ), Example 3 (1866 μmol·g -1 ), Example 4 (2420 μmol·g -1It exhibited significantly higher activity than ). In the case of the comparative example, Comparative Example 1 (Cu2O superparticles) was 282 μmol·g -1 , Comparative Example 2 (polydopamine) is 1398 μmol·g -1 It was confirmed that the activity was limited compared to the embodiments of the present invention. This result is attributed to the fact that the electron transfer pathway is improved and interfacial interactions are maximized by coating polydopamine (200) on the surface of the Cu2O superparticle (100).

[0132] The data in the upper right corner represents the result of a direct comparison between Example 2 and Comparative Example 3 (simple mixture). After a 2-hour reaction, Example 2 yielded approximately 2154 μmol·g -1 While it produced H2O2 at a certain level, Comparative Example 3 (simple mixture) produced approximately 536 μmol·g -1 It was nothing more than that. This proves that when polydopamine is simply mixed, an effective charge transfer pathway is not formed, and a strong synergistic effect is exerted only when a structure is formed in which polydopamine (200) is coated on the surface (100) of copper (I) oxide superparticles.

[0134] The data in the lower left of Fig. 7 shows the difference in H2O2 production depending on the reaction conditions. Under the condition of light irradiation in the presence of O2, approximately 2154 μmol·g -1 H2O2 was produced, but in an air atmosphere, 1891 μmol·g -1 It decreased to the level of approximately 882 μmol·g, respectively, under conditions lacking light or O2. -1 , 490μmol·g -1 It was significantly reduced, demonstrating that the photocatalytic reaction of the present invention is governed by photoactivity and oxygen reduction reaction (ORR).

[0136] The data at the bottom right of Fig. 7 is the result of the H2O2 stability evaluation. In this case, the y-axis (C / C0) represents the ratio of the residual concentration (C) to the initial concentration (C0) of hydrogen peroxide, and the closer the value is to 1, the more stable the hydrogen peroxide remains without decomposition. Comparative Example 1 (Cu2O superparticles) showed reduced stability as approximately 45% of the initial H2O2 decomposed, whereas Comparative Example 2 (polydopamine) showed almost no H2O2 decomposition for 2 hours. Example 2 showed a slightly higher level of H2O2 decomposition than Comparative Example 2 (polydopamine), but significantly lower than Comparative Example 1 (Cu2O superparticles), confirming that the polydopamine (200) coating layer suppressed excessive H2O2 decomposition and improved photocatalytic stability.

[0138] Long-term stability was evaluated under light on / off conditions and is shown in Fig. 8. As a result of alternately irradiating light and darkness at 3-hour intervals using Example 2, approximately 2000 μmol·g was emitted per cycle during the light section. -1 H2O2 was generated at a certain level, and generation was suppressed in the dark section.

[0139] These results further confirm that the photocatalytic reaction of the present invention is clearly induced by photoactivity and demonstrate that performance is stably maintained even during continuous reactions for a long time.

[0141] The reusability of Example 2 was evaluated and is shown in FIG. 9. After centrifugation, the catalyst was recovered and redispersed in water, and four repeated experiments were performed. As a result, the initial activity was maintained at 95% or higher in each cycle. In addition, XRD analysis results before and after the photocatalytic reaction showed that the main diffraction peaks did not change except for the formation of a small amount of CuO due to the oxidation of some copper (I) oxide superparticles (100), confirming that the crystal structure was maintained stably throughout the reaction.

[0143] The photocatalyst of the present invention, particularly Example 2, is about 2500 to 3000 μmol·g -1It was confirmed that it exhibits a level of H2O2 generation, a uniform polydopamine (200) coating layer with a thickness of about 1.5 to 2.0 nm, and reusability of more than 95%, showing significantly superior performance and durability compared to existing copper (I) oxide superparticles (100) or polydopamine alone and simple mixtures.

[0145] <Experimental Example 4> Analysis of Optical Physical and Electrochemical Properties

[0146] Photophysical and electrochemical properties were evaluated for Example 2, Comparative Example 1, and Comparative Example 2. The analysis results are shown together in Figures 10 to 13.

[0148] First, to verify the separation efficiency of photogenerated electrons and holes, a photoluminescence (PL) spectrum was measured using an excitation wavelength of 520 nm (left side of FIG. 10). Comparative Example 1 (Cu2O superparticles) showed a strong luminescence intensity, indicating rapid electron-hole recombination, while Comparative Example 2 (polydopamine) showed almost no luminescence. On the other hand, Example 2 showed a decrease in luminescence intensity of about 30 to 40% compared to Comparative Example 1 (Cu2O superparticles), confirming that charge recombination was suppressed and electron-hole separation efficiency was improved. This is also consistent with the electron transfer results from the copper (I) oxide superparticles (100) to the polydopamine (200) layer presented in the XPS analysis of the preceding Experimental Example 2.

[0150] Charge transfer characteristics were evaluated using a Nyquist plot via electrochemical impedance spectroscopy (EIS) (right side of Fig. 10). The plot typically shows the solution resistance (Rs), constant phase element (CPE), and charge transfer resistance (R). ct It can be fitted by an equivalent circuit model composed of ). As a result of the analysis, the semicircle radius of Example 2 was found to be the smallest, and the corresponding R ctThe value was calculated to be approximately 3.3 kΩ. This is lower than the approximately 4.0 kΩ of Comparative Example 1 (Cu2O superparticles) and the approximately 6.9 kΩ of Comparative Example 2 (polydopamine). This reduction in charge transfer resistance is the result of the formation of an efficient electron transfer pathway between the copper (I) oxide superparticles (100) and the polydopamine (200) coating layer, which contributes to promoting interfacial charge transfer and suppressing electron-hole recombination in the photocatalytic reaction.

[0152] Next, Mott-Schottky analysis (C S -2 The flat band potential of each sample was confirmed through the potential curve (Fig. 11). Comparative Example 1 (Cu2O superparticle) showed a negative slope and exhibited p-type semiconductor characteristics, and the flat band potential was confirmed to be approximately +1.59 V (vs. RHE). On the other hand, Comparative Example 2 (polydopamine) showed a positive slope and exhibited n-type semiconductor characteristics, and the flat band potential was measured to be -0.70 V (vs. RHE). Example 2 showed p-type behavior similar to Comparative Example 1 (Cu2O superparticle), but the flat band potential was negatively transitioned to +1.40 V (vs. RHE), confirming a configuration in which electron transport became more favorable.

[0154] In addition, UV-Vis Tauc plot analysis (Fig. 12) showed that the band gap of Comparative Example 1 (Cu2O superparticles) was 2.1 eV and that of Comparative Example 2 (polydopamine) was 1.6 eV, while Example 2 showed an intermediate value of 1.8 eV. This result reflects the combined electronic structures of the two components, suggesting that they possess an energy alignment favorable for photoexcited electrons to move into the polydopamine layer. For reference, (αhν) per sample 2 The y-axis range for each panel varies depending on the absolute difference in size, but it does not affect the estimation of Eg.

[0156] Synthesizing these results, the band alignment of Comparative Example 1 (Cu2O superparticle) and Comparative Example 2 (polydopamine) is shown in FIG. 13. According to the alignment, electrons move from the Cu2O conduction band to the polydopamine conduction band, and holes remain in the Cu2O valence band to form a type-II or direct Z-scheme heterojunction configuration.

[0157] Consequently, since the photocatalyst (10) of the present invention is a composite in which the Cu2O superparticle of Comparative Example 1 and the polydopamine component of Comparative Example 2 are combined, the band alignment of the photocatalyst (10) according to the present invention suppresses electron-hole recombination and extends the lifetime of the charge carrier, thereby 2e - It can be confirmed that the hydrogen peroxide generation reaction through the ORR pathway is energetically favorable.

[0159] The results of the radical scavenger experiment (Fig. 14) also support this.

[0160] As a result of observing the time-dependent change in H2O2 production depending on the addition of the reagent of Example 2 upon light irradiation under O2-saturated conditions, there was no significant change in H2O2 production when IPA was added, but the production amount was suppressed by more than 70% when BQ was added. Through this, O2 - It was confirmed that radicals are the main active species of this system, and that the contribution of OH radicals is negligible.

[0161] Accordingly, the photocatalyst (10) of the present invention improves electron-hole separation, offers advantageous band alignment, and selective O2 - Stable and efficient H2O2 production can be achieved through the characteristic of radical generation.

[0163] In summary, Example 2 shows reduced PL emission intensity (improved electron-hole separation) and lower charge transfer resistance (R) compared to Comparative Example 1 (Cu2O superparticles) and Comparative Example 2 (polydopamine). ct 3.3 kΩ), pn heterojunction-based band alignment (2.1 eV vs. 1.6 eV), O2 -Radical-selective reactivity was simultaneously secured. This supports the fact that the photocatalyst of the present invention possesses high efficiency and stability, and has structural and electronic characteristics optimized for H2O2 generation.

[0165] <Experimental Example 5> Analysis of Photocatalytic Reaction Mechanism

[0166] To elucidate the photocatalytic reaction mechanisms of Example 2, Comparative Example 1 (Cu2O superparticles), and Comparative Example 2 (polydopamine), valence band XPS spectrum analysis was performed, and a band alignment diagram was derived based on this. The results are shown in Fig. 15.

[0168] As a result of valence band XPS spectrum analysis, the valence band potential (E_VB) of Comparative Example 1 (Cu2O superparticle) was found to be approximately 0.5 eV, and the valence band potential of Comparative Example 2 (polydopamine) was found to be approximately 1.0 eV (top of Fig. 15). This is in good agreement with the valence band energy levels of Cu2O and polydopamine generally reported in the literature (0.4–0.6 eV and 0.9–1.1 eV, respectively), supporting the reliability of the XPS analysis results of the present invention and ensuring the validity of the band alignment schematic presented thereafter.

[0170] Based on these results, the band alignment formed when Comparative Example 1 (Cu2O superparticles) and Comparative Example 2 (polydopamine) come into contact is schematically shown at the bottom of Fig. 15. In Fig. 15, the polydopamine layer is labeled 'PDA' for convenience, but this refers to 'polydopamine'. Generally, when a p-type semiconductor, Cu2O, and an n-type semiconductor, polydopamine, are joined, a type-II heterojunction is formed. At this time, photoexcited electrons move from the conduction band of Cu2O to the conduction band of polydopamine, while holes remain in the valence band of Cu2O. This energy gradient not only effectively suppresses electron-hole recombination but also provides an electron transport environment optimized for the two-electron oxygen reduction reaction.

[0172] In addition, the valence band holes of Cu2O react with the catechol functional group of polydopamine to form a carbonyl group (C=O), thereby regenerating the active site without a sacrificial agent (external electron donor, e.g., ethanol, IPA, etc.). At the same time, electrons accumulated in the conduction band of polydopamine (200) participate in the oxygen reduction reaction and produce H2O2 through the selective two-electron oxygen reduction reaction pathway.

[0174] Accordingly, since the photocatalyst (10) of the present invention is a composite of the Cu2O superparticle of Comparative Example 1 and the polydopamine component of Comparative Example 2, the polydopamine (200) coating layer acts as a protective layer that blocks the generated H2O2 from coming into direct contact with the surface of the Cu2O superparticle (100), and at the same time, provides an electron transfer pathway from the Cu2O superparticle (100) to the polydopamine (200), thereby improving charge transfer efficiency.

[0176] In summary, Example 2 demonstrated excellent photocatalytic performance by simultaneously securing structural stability and electronic properties through four mechanisms compared to Comparative Example 1 (Cu2O superparticles) and Comparative Example 2 (polydopamine): inhibition of electron-hole recombination, promotion of selective two-electron oxygen reduction reaction due to optimized energy band alignment, regeneration of active sites by catechol-carbonyl conversion, protection of the polydopamine (200) coating layer, and charge transfer function.

[0178] As described above, the copper(I) oxide superparticle-based photocatalyst (10) and the method for manufacturing the same (S10) according to the present invention have a core-shell structure in which a polydopamine (200) layer with an average thickness of 1 to 3 nm and 2.0 to 8.0 wt% is uniformly coated on the surface of the copper(I) oxide superparticle (100), and enables stable and efficient production of hydrogen peroxide (H2O2) without the addition of a sacrificial agent.

[0180] The photocatalyst (10) of the present invention has a g / m³ of 2500 to 3000 μmol·g when irradiated for 5 hours. -1It simultaneously secured excellent durability with a high amount of H2O2, stable performance for at least 21 hours under light on / off repeated conditions, and initial activity of over 95% even after reuse four or more times, as well as enhanced reactivity through four mechanisms: inhibition of electron-hole recombination, selective two-electron oxygen reduction reaction pathway, regeneration of the active site, and inhibition of H2O2 decomposition.

[0182] Accordingly, the present invention presents a rational composite design strategy capable of overcoming the limitations of existing copper(I) oxide or polydopamine monolithic systems, and provides a practical means to manufacture a high-efficiency, high-durability photocatalyst in a single process (one-pot) that can be utilized in the fields of environmental purification, water purification, and sustainable energy conversion and storage technology.

[0184] The above-described embodiments are merely exemplary, and various other embodiments modified therefrom are possible for those skilled in the art.

[0185] Therefore, the true technical scope of protection of the present invention should include not only the above embodiments but also other embodiments that are variously modified according to the technical concept of the invention described in the following claims. Explanation of the symbols

[0186] 10: Copper(I) oxide superparticle-based photocatalyst for hydrogen peroxide generation 100: Copper(I) oxide superparticles (Cu, O distribution) 200: Polydopamine coating layer (C, N distribution) S10: Method for manufacturing a hydrogen peroxide-generating photocatalyst based on copper(I) oxide superparticles S100: Preparation step for copper(I) oxide synthesis solution S300: Copper(I) oxide superparticle formation step S500: Dopamine addition step S700: Polydopamine coating step

Claims

Claim 1 A photocatalyst comprising: copper(I) oxide superparticles; and polydopamine formed on the surface of the copper(I) oxide superparticles; wherein the copper(I) oxide superparticles form a core and the polydopamine forms a shell on the surface of the copper(I) oxide superparticles, the photocatalyst has a core-shell structure, the average thickness of the polydopamine is 1 to 3 nm, the charge transfer resistance of the photocatalyst is 3.3 kΩ or less, electron-hole recombination is suppressed by interfacial charge transfer between the copper(I) oxide superparticles and the polydopamine, and hydrogen peroxide is generated without the addition of a sacrificial agent. Claim 2 delete Claim 3 A hydrogen peroxide generating photocatalyst based on copper(I) oxide superparticles according to claim 1, wherein the polydopamine is included in a mass percentage of 2.0 to 8.0 wt%. Claim 4 A copper(I) oxide superparticle-based hydrogen peroxide generating photocatalyst according to claim 1, wherein the polydopamine is produced by the polymerization reaction of dopamine contained in an alkaline solution containing the copper(I) oxide superparticles at a concentration of 2 to 8 mg / mL. Claim 5 The photocatalyst for hydrogen peroxide generation based on copper(I) oxide superparticles according to claim 1, wherein the photocatalyst generates at least 1860 μmol / g of hydrogen peroxide during 5 hours of light irradiation under oxygen-saturated conditions without the addition of a sacrificial agent. Claim 6 In claim 1, the photocatalyst is a hydrogen peroxide generating photocatalyst in which the amount of hydrogen peroxide produced is maintained or increased for at least 21 hours during a process of repeating the on / off of an artificial light source simulating sunlight conditions at a predetermined cycle. Claim 7 A hydrogen peroxide generating photocatalyst according to claim 1, wherein the photocatalyst maintains 95% or more of its initial hydrogen peroxide generating performance even when the process of performing a hydrogen peroxide generation reaction by maintaining the on state of an artificial light source simulating sunlight conditions for a predetermined time, and then recovering and reusing it is repeated at least four times. Claim 8 In claim 1, the photocatalyst is a hydrogen peroxide generating photocatalyst based on copper(I) oxide superparticles having an average diameter in the range of 200 to 2200 nm. Claim 9 A method for manufacturing a photocatalyst for generating hydrogen peroxide based on copper(I) oxide superparticles, comprising: a step of preparing a copper(I) oxide synthesis solution; a step of stirring the synthesis solution to form copper(I) oxide superparticles; a step of adding dopamine to the synthesis solution in which the copper(I) oxide superparticles are formed; and a step of self-polymerizing the dopamine under alkaline conditions to form a polydopamine shell on the surface of the copper(I) oxide superparticles; wherein the polydopamine is formed with an average thickness of 1 to 3 nm, the charge transfer resistance of the photocatalyst is 3.3 kΩ or less, and electron-hole recombination is suppressed by interfacial charge transfer between the copper(I) oxide superparticles and the polydopamine. Claim 10 A method for producing a hydrogen peroxide-generating photocatalyst based on copper(I) oxide superparticles according to claim 9, wherein the step of preparing the copper(I) oxide synthesis solution is to prepare a synthesis solution containing copper acetate monohydrate and L-ascorbic acid, and the step of adding dopamine is to add the dopamine at a concentration of 2 to 8 mg / mL.

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