Supported particles, mixture, and method for producing supported particles

Abstract

To provide novel supported particles employing a noble metal as a co-catalyst and being useful as a photocatalyst.SOLUTION: A supported particle 1 has noble metal clusters 2 each composed of 1 to 30 atoms, or noble metal single atoms, supported on a photocatalyst particle 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to supported particles, mixtures, and methods for making supported particles. [Background technology]

[0002] A photocatalyst that uses a noble metal as a promoter is disclosed, for example, in Patent Document 1. Considering the widespread use of photocatalysts, there has been a strong demand for the development of new types of photocatalysts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2021-527555 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure has been made in view of the above circumstances, and aims to provide novel support particles that use a noble metal as a promoter and are useful as photocatalysts. The present invention can be realized as the following aspects. [Means for solving the problem]

[0005] [1] A supported particle obtained by supporting a noble metal cluster or a noble metal single atom having an atomic number of 1 to 30 on a photocatalyst particle.

[0006] [2] The photocatalyst particles are selected from the group consisting of carbon nitride particles and titanium oxide particles.

[0007] [3] The support particle according to [1] or [2], wherein a protective agent is not bonded to the noble metal cluster or the noble metal single atom.

[0008] [4] A mixture obtained by mixing the supported particles according to [1] or [2] with unsupported photocatalyst particles that do not support the noble metal clusters or the noble metal single atoms.

[0009] [5] The mixture according to [4], wherein the amount of precious metal is 0.05% by mass or more and 0.5% by mass or less in 100% by mass of the mixture.

[0010] [6] A method for producing the supported particles according to [1] or [2], a generating step of generating the noble metal cluster or the noble metal single atom having an atomic number of 1 to 30 by magnetron sputtering; and a supporting step of landing the noble metal clusters or the noble metal single atoms on the photocatalyst particles to support them. [Effects of the Invention]

[0011] The support particles of the present disclosure have high performance and can reduce the amount of precious metals used in various fields. When the photocatalyst particles are selected from the group consisting of carbon nitride particles and titanium oxide particles, the catalytic activity is increased. When no protective agent is bonded to the noble metal cluster or the noble metal single atom, the performance degradation caused by the protective agent is suppressed, and the activity becomes extremely high. It is advantageous from the viewpoint of cost to mix supported particles with unsupported photocatalyst particles that do not support precious metal clusters or precious metal single atoms. When the amount of precious metal in the mixture is 0.05% by mass or more and 0.5% by mass or less, high activity can be achieved at low cost. Therefore, performance can be improved while reducing the amount of precious metal used, which reduces costs and promotes widespread use. According to the manufacturing method of the present disclosure, high-performance support particles can be manufactured. [Brief explanation of the drawings]

[0012] The invention is further explained in the following detailed description, giving non-limiting examples of exemplary embodiments according to the invention, and with reference to the mentioned drawings, in which: [Figure 1] FIG. 1 is a conceptual diagram of an example of a support particle according to the present disclosure. [Figure 2] FIG. 1 is a conceptual diagram of a conventional inorganic oxide supporting a noble metal. [Figure 3] FIG. 1 is a conceptual diagram showing an example of an apparatus for carrying out a method for producing supported particles. [Figure 4] This is an MS spectrum of a Pt cluster. [Figure 5] This is a TEM image of Pt cluster-supported titanium oxide. [Figure 6] This is a TEM image of Pt cluster-supported carbon nitride. [Figure 7] 1 is a graph showing the change over time in the amount of hydrogen (H 2 ) produced in the dehydrogenation reaction of triethanolamine by a photocatalyst (support: carbon nitride). [Figure 8] 1 is a graph showing the change over time in the amount of H 2 produced in the dehydrogenation reaction of methanol by a photocatalyst (support: titanium oxide). [Figure 9] 1 is a graph showing the relationship between the "amount of Pt supported in the mixture" and the "slope of the approximate line in the change over time in the amount of H2 generated." DETAILED DESCRIPTION OF THE INVENTION

[0013] The matters set forth herein are for illustrative purposes only and are intended to provide an illustrative description of the embodiments of the present invention, with the aim of providing what is believed to be the most effective and easily understandable explanation of the principles and conceptual features of the present invention. In this respect, it is not intended to show structural details of the present invention beyond the extent necessary for a fundamental understanding of the present invention, and the description, taken together with the drawings, will make clear to those skilled in the art how some aspects of the present invention may be actually embodied.

[0014] The present disclosure will be described in detail below. In this specification, when a numerical range is indicated using "-", it is intended to include both the lower and upper limits unless otherwise specified. For example, the expression "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". Furthermore, in this specification, the upper and lower limits of each numerical range can be arbitrarily combined. Furthermore, the drawings are conceptual diagrams for explaining the disclosed contents and do not accurately depict actual dimensions.

[0015] 1. Support particles 1 The support particle 1 is formed by supporting a noble metal cluster 2 having 1 to 30 atoms or a noble metal single atom on a photocatalyst particle 3. FIG. The supported particle 1 may be in a form in which two or more types of noble metal clusters 2 or noble metal single atoms having different numbers of atoms are supported on the photocatalyst particle 3. For example, noble metal clusters having different numbers of atoms as shown in Fig. 4 described later may be supported on the same photocatalyst particle 3.

[0016] (1) Noble metal cluster 2 or noble metal single atom The number of atoms constituting the noble metal cluster 2 is 1 or more and 30 or less, preferably 2 or more and 20 or less, and more preferably 3 or more and 15 or less, from the viewpoint of performance as a co-catalyst for a photocatalyst. Examples of the noble metal elements constituting the noble metal cluster 2 or the noble metal single atom include gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), and osmium (Os). The noble metal cluster 2 may be composed of one type of noble metal atom, or may contain two or more types of noble metal atoms. When the noble metal cluster 2 contains two or more types of noble metal atoms, the noble metal cluster 2 becomes a noble metal alloy. It is preferable that the protective agent 6 is not bonded to the precious metal cluster 2 or the precious metal single atom. Here, the protective agent refers to an organic molecule (organic compound) used in the synthesis of the precious metal cluster, such as triphenylphosphine (TPP). Figure 2 shows the particles disclosed in JP-A-2021-527555. In Figure 2, reference numeral 4 indicates an inorganic oxide, reference numeral 5 indicates a precious metal particle, and reference numeral 6 indicates a protective agent. When no organic molecule as the protective agent 6 is bonded to the noble metal cluster 2 or the noble metal single atom, it is presumed that the access to the noble metal surface is improved, resulting in improved catalytic activity.

[0017] (2) Photocatalyst particles 3 The photocatalyst particles 3 are not particularly limited as long as they are particles having photocatalytic activity. The photocatalyst particles 3 are preferably selected from the group consisting of carbon nitride particles and titanium oxide particles. As the carbon nitride particles, for example, graphite carbon nitride (g-CN) particles are preferred. There are no particular limitations on the average particle size of the photocatalyst particles 3. The average particle size D50 of the photocatalyst particles 3 is preferably 1 nm or more and 5000 nm or less, more preferably 2 nm or more and 3000 nm or less, and even more preferably 2 nm or more and 2000 nm or less. The average particle size D50 can be measured by a laser diffraction method.

[0018] (3) Amount of precious metals carried There are no particular limitations on the amount of precious metal supported on the support particles 1. From the viewpoint of suppressing production costs while fully exerting catalytic function, the amount of precious metal supported is preferably 0.005% by mass or more and 40% by mass or less, more preferably 0.01% by mass or more and 20% by mass or less, and even more preferably 0.01% by mass or more and 10% by mass or less, relative to 100% by mass of the support particles 1.

[0019] (4) Effect of Support Particle 1 The support particles 1 of the present disclosure are novel particles and are useful as photocatalysts.

[0020] 2. Method for producing the support particles 1 There is no particular limitation on the method for producing the support particles 1. Here, an example of a suitable method for producing the support particles 1 will be described. The manufacturing method of this supported particle 1 includes a generation step of generating a precious metal cluster 2 or a precious metal single atom having an atomic number of 1 to 30, and a support step of landing the precious metal cluster 2 or the precious metal single atom on a photocatalyst particle 3 and supporting it.

[0021] (1) Generation process The generation step is not particularly limited, and a wide variety of methods can be used as long as they are capable of generating (generating) the noble metal clusters 2 or noble metal monoatoms. For example, magnetron sputtering, ion sputtering, ion beam sputtering, laser evaporation, etc. can be used. Among these, magnetron sputtering is preferably used from the viewpoint of the amount of ions and their stability. The noble metal cluster 2 or noble metal single atom generated in the generation step has an atomic number of 1 or more and 30 or less, and from the viewpoint of efficient catalytic reaction, the atomic number is preferably 2 or more and 20 or less, and more preferably 3 or more and 15 or less.

[0022] (2) Supporting process In the supporting step, the noble metal clusters 2 or noble metal single atoms are landed on the photocatalyst particles 3 and supported thereon. For the photocatalyst particles 3, the above description of "1.(2) Photocatalyst particles 3" can be applied as is.

[0023] (3) An example of an apparatus for carrying out the manufacturing method of the support particles 1 Here, an example of a manufacturing apparatus 7 for manufacturing the support particles 1 that implements the above manufacturing method will be described (FIG. 3). The manufacturing apparatus 7 for supporting particles 1 includes a cluster generator 10. The cluster generator 10 includes a vacuum chamber 11, a cluster growth cell 12 installed in the chamber 11, and a sputtering source 13 (magnetron sputtering source) installed in the cluster growth cell 12. The cluster growth cell 12 is surrounded by a liquid nitrogen jacket 14, and liquid nitrogen (N2) is configured to circulate within the liquid nitrogen jacket 14. The cluster generator 10 further includes, as components of a control system, a control device 15 and a pulsed power supply 16 for the sputtering source.

[0024] The cluster generation apparatus 10 includes a first inert gas supply pipe 17 and a second inert gas supply pipe 18. The first inert gas supply pipe 17 supplies a first inert gas (e.g., argon gas (Ar)) for generating plasma to the sputtering source 13. The second inert gas supply pipe 18 supplies a second inert gas (e.g., helium gas (He)) into the cluster growth cell 12 for cooling and agglomerating metal atoms and metal ions generated from the sputtering source 13 and growing them as clusters. The main part of the second inert gas supply pipe 18 is housed within the liquid nitrogen jacket 14, spirals around the inside of the liquid nitrogen jacket 14, and has one end protruding into the inside of the cluster growth cell 12.

[0025] In this way, the second inert gas such as helium cooled by liquid nitrogen can be introduced into the cluster growth cell 12. The pressure inside the cluster growth cell 12 is maintained at approximately 10 to 40 Pa. Note that devices such as a pressure gauge provided in the cluster growth cell 12 for pressure control and a mass flow controller provided in the gas supply system are not shown in the figure. The cluster generating device 10 further includes an exhaust device 19 such as a turbo molecular pump, and the inside of the chamber 11 is vacuumed to a predetermined degree (for example, 10 -1 ~10 -4 The pressure is evacuated to a pressure of 1000 Pa.

[0026] The sputtering source 13 is composed of a target 131, an anode 132, and a magnet unit 133, and the target 131 is connected as a cathode to a pulsed power supply 16 for the sputtering source. Ar gas is supplied into the cluster growth cell 12 from a first inert gas supply pipe 17, and pulsed power is supplied from the pulsed power supply 16 for the sputtering source, thereby generating a glow discharge between the target 131 and the anode 132. That is, a high voltage is applied in pulses between the target 131 and the anode 132, thereby generating a glow discharge between the target 131 and the anode 132. In addition, by applying a magnetic field near the surface of the target 131 with the magnet unit 133, the cluster generation apparatus 10 of this embodiment performs magnetron sputtering, making it possible to generate an even stronger glow discharge.

[0027] The tip of the first inert gas supply pipe 17 is configured to inject the first inert gas from one or more locations between the target 131 and the anode 132 of the sputtering source 13. However, the present invention is not limited to this configuration, and any configuration can be adopted as long as it is capable of supplying the first inert gas toward the target 131. The sputtering source 13 is accommodated in the cluster growth cell 12 so as to be movable in the axial direction of the tube. This defines the extension distance of the cluster growth region in the axial direction of the tube. The extension distance in the axial direction of the tube means the growth region length, i.e., the distance from the surface of the target 131 to the beam outlet 121.

[0028] To generate clusters, a second inert gas cooled to liquid nitrogen temperature is introduced into the cluster growth cell 12, and a first inert gas is supplied to the sputtering source 13, while pulsed power is supplied from the sputtering source pulsed power supply 16. When pulsed power is supplied, sputtered particles such as neutral atoms and ions originating from the target 131 are emitted as a mass from the target 131 into the second inert gas.

[0029] This cluster is emitted at intervals equal to the repetition frequency of the pulsed power applied to the sputtering source 13 and moves along the flow of the second inert gas. At this time, the sputtered particles such as neutral atoms and ions that make up the cluster combine with each other in the second inert gas to generate clusters of various sizes. The generated clusters pass through the beam outlet 121 of the cluster growth cell 12 and are then deposited on the photocatalyst particles 3.

[0030] (4) Effect of the manufacturing method of the support particles 1 In the method for producing the support particles 1 of the present disclosure, various reagents (including organic solvents) for synthesizing the support particles 1 are not required. In the method for producing the supported particles 1 of the present disclosure, it is also possible to produce the supported particles 1 in which the precious metal clusters 2 of a precious metal alloy are supported on the photocatalyst particles 3. The method for producing the supported particles 1 of the present disclosure can also produce supported noble metal clusters 2 with particle diameters of 1 nm or less.

[0031] 3.Mixture The mixture is a mixture of precious metal clusters 2 or supported particles 1 carrying the precious metal single atoms, and unsupported photocatalyst particles (hereinafter simply referred to as "unsupported photocatalyst particles") that do not carry precious metal clusters 2 or precious metal single atoms.

[0032] (1) Support particles 1 The support particles 1 used in the mixture can be the support particles 1 described in the section "1. Support particles 1." There are no particular limitations on the amount of precious metal supported on the support particles 1 used in the mixture. From the viewpoint of suppressing production costs while fully exerting catalytic function, the amount of precious metal supported on the support particles 1 used in the mixture is preferably 0.005% by mass or more and 40% by mass or less, more preferably 0.01% by mass or more and 20% by mass or less, and even more preferably 0.01% by mass or more and 10% by mass or less, relative to 100% by mass of the support particles 1.

[0033] The average particle size of the unsupported photocatalyst particles is not particularly limited. The average particle size D50 of the photocatalyst particles 3 is preferably 1 nm or more and 5000 nm or less, more preferably 2 nm or more and 2000 nm or less, and even more preferably 2 nm or more and 1000 nm or less. The average particle size D50 can be measured by a laser diffraction method.

[0034] (2) Amount of precious metals supported in the mixture The amount of precious metal supported in the mixture is not particularly limited. The amount of precious metal in the mixture is preferably 0.05% by mass to 0.5% by mass, and more preferably 0.05% by mass to 0.15% by mass, based on 100% by mass of the mixture. When preparing the mixture using support particles 1 in which precious metal clusters 2 or precious metal single atoms having an atomic number of 1 to 30 are supported on photocatalyst particles 3, a phenomenon is observed in which the utilization efficiency of the precious metal increases when the amount of precious metal in the mixture is within a specific mass% range. In contrast, when preparing the mixture using support particles in which precious metal nanoparticles consisting of hundreds to thousands of precious metal atoms are supported on photocatalyst particles, even if the amount of precious metal (mass%) in the mixture is changed, the improvement in the utilization efficiency of the precious metal is inferior to that in the case of clusters. Therefore, it can be seen that the support particles 1 in which precious metal clusters 2 or precious metal single atoms having an atomic number of 1 to 30 are supported on photocatalyst particles 3 according to the present disclosure are extremely useful from the perspective of improving the utilization efficiency of the precious metal.

[0035] (3) Effect of mixture By using the mixture of the present disclosure, the amount of precious metal used can be reduced and the utilization efficiency of the precious metal can be increased. [Example]

[0036] Hereinafter, a more specific explanation will be given by way of examples. In the following experiments, "Pt cluster-supported carbon nitride" and "Pt cluster-supported titanium oxide" correspond to "supported particles in which noble metal clusters or noble metal single atoms having 1 to 30 atoms are supported on photocatalyst particles" in this specification.

[0037] 1. Preparation of Supported Particles Pt cluster ions (approximately 15-mer or less, particle size 0.5-1 nm) were generated by magnetron sputtering and then landed on the surface of photocatalyst particles (photocatalyst powder), thereby supporting Pt clusters on the photocatalyst particles (photocatalyst powder). Carbon nitride (g-CN) and titanium oxide (TiO, ST-01) were used as photocatalyst particles. The amount of hydrogen (H2) produced in photocatalytic reactions (dehydrogenation of triethanolamine and dehydrogenation of methanol) using the resulting supported particles (Pt cluster-supported carbon nitride and Pt cluster-supported titanium oxide) was investigated. For comparison, we also investigated the amount of H2 generated when using Pt nanoparticle-supported carbon nitride (Pt nanoparticles synthesized by photoprecipitation, Pt nanoparticle size approximately 2-3 nm), Pt nanoparticle-supported titanium oxide (Pt nanoparticles synthesized by photoprecipitation, Pt nanoparticle size approximately 2-3 nm), unsupported carbon nitride, and unsupported titanium oxide. In each of the Pt cluster-supported carbon nitride, Pt cluster-supported titanium oxide, Pt nanoparticle-supported carbon nitride, and Pt nanoparticle-supported titanium oxide, the amount of Pt supported was 1 wt % (=1 weight %=1 mass %).

[0038] 2. Confirmation of Pt cluster The atomic number of the Pt clusters generated by magnetron sputtering was confirmed by mass spectrometry (MS). As shown in Figure 4, the atomic number was 2-16.

[0039] 3. TEM observation of the structure of Pt cluster-supported titanium oxide and Pt cluster-supported carbon nitride The structures of Pt cluster-supported titanium oxide and Pt cluster-supported carbon nitride were observed by TEM. Figure 5 shows a TEM image of Pt cluster-supported titanium oxide, and Figure 6 shows a TEM image of Pt cluster-supported carbon nitride. In both TEM images, Pt clusters of approximately 1 nm or less were confirmed.

[0040] 4. Investigation of the amount of H2 produced in the photocatalytic reaction (1) Dehydrogenation of triethanolamine (1.1) Dehydrogenation of triethanolamine over Pt nanoparticle-supported carbon nitride 50 mg of Pt nanoparticle-supported carbon nitride and a Teflon®-coated stirrer (length 10 mm) were placed in a hard glass test tube (18 mm × 180 mm, P-18M, Nichiden Rika Glass Co., Ltd., transmission wavelength ≥ 290 nm), and 5.0 cm of 1 M triethanolamine aqueous solution was added. 3 After adding an aqueous solution of chloroplatinic acid so that the Pt content of the photocatalyst was 1 wt%, argon (Ar) was bubbled through the test tube for 20 minutes to remove the air from inside, and the tube was sealed with a double cap and parafilm. The tube was then set up for light irradiation (1.2 W light output near the sample) and irradiated with a xenon lamp at 298 K for 90 minutes. The change in the amount of H2 produced over time was analyzed using a gas chromatograph (3000 Micro GC, Inficon Co., Ltd.).

[0041] (1.2) Dehydrogenation of triethanolamine over Pt cluster-supported carbon nitride 50.5 mg of Pt cluster-supported carbon nitride and a Teflon-coated stirrer (10 mm long) were placed in a hard glass test tube (P-18M) and 5.0 cm of 1 M triethanolamine aqueous solution was added. 3 The test tube was then bubbled with Ar for 20 minutes to remove air from the tube, after which it was sealed with a double cap and parafilm. The tube was then set up for light irradiation (1.2 W light intensity near the sample) and irradiated with a xenon lamp at 298 K for 90 minutes. The time course of H2 production was analyzed using a gas chromatograph (3000 Micro GC).

[0042] (1.3) Results The results are shown in Figure 7. As shown in Figure 7, Pt cluster-supported carbon nitride (Pt clusters@g-CN4), as well as Pt nanoparticle-supported carbon nitride (Pt nanoparticles@g-CN4), exhibited significantly improved photocatalytic performance compared to unsupported carbon nitride (g-CN4). In other words, when carbon nitride was used as a photocatalyst powder, the performance was significantly improved by supporting Pt. Regarding the amount of H2 generated, there was no significant difference due to differences in Pt particle size, indicating that Pt clusters can function as a photocatalytic cocatalyst in the same way as Pt nanoparticles.

[0043] (2) Methanol dehydrogenation (2.1) Methanol dehydrogenation over Pt nanoparticle-supported titanium oxide 50 mg of Pt nanoparticle-supported titanium oxide and a Teflon-coated stirrer (10 mm long) were placed in a hard glass test tube (P-18M), and 5.0 cm of 50 vol% methanol aqueous solution was added. 3 After adding an aqueous solution of chloroplatinic acid so that the Pt content of the photocatalyst was 1 wt%, Ar was bubbled through the test tube for 20 minutes to remove the air, and the tube was sealed with a double cap and parafilm. The tube was then set up for light irradiation (1.2 W light intensity near the sample) and irradiated with a xenon lamp at 298 K for 90 minutes. The change in the amount of H2 produced over time was analyzed using a gas chromatograph (3000 Micro GC).

[0044] (2.2) Methanol dehydrogenation over Pt cluster-supported titanium oxide 50.5 mg of Pt cluster-supported titanium oxide and a Teflon-coated stirrer (length 10 mm) were placed in a hard glass test tube (P-18M), and 5.0 cm of 50 vol% methanol aqueous solution was added. 3 The test tube was then bubbled with Ar for 20 minutes to remove air from the tube, after which it was sealed with a double cap and parafilm. The tube was then set up for light irradiation (1.2 W light intensity near the sample) and irradiated with a xenon lamp at 298 K for 90 minutes. The time course of H2 production was analyzed using a gas chromatograph (3000 Micro GC).

[0045] (2.3) Results The results are shown in Figure 8. As shown in Figure 8, Pt cluster-supported titanium oxide (Pt clusters@TiO2), like Pt nanoparticle-supported titanium oxide (Pt nanoparticles@TiO2), had significantly improved photocatalytic performance compared to unsupported titanium oxide (TiO2). In other words, when titanium oxide is used as a photocatalyst powder, performance is significantly improved by supporting Pt. No significant difference in H2 generation was observed due to differences in Pt particle size, indicating that Pt clusters can function as a photocatalytic co-catalyst in the same way as Pt nanoparticles.

[0046] (3) Advantages of gas-phase nanocluster synthesis One of the advantages of using a gas-phase nanocluster synthesis apparatus to prepare cocatalysts for photocatalysis is that the cluster composition can be controlled by selecting the metal plate (target) that serves as the cluster source. In other words, alloying is possible using a gas-phase nanocluster synthesis apparatus. This is a major advantage over the photodeposition method, which can only prepare nanoparticles of a single composition.

[0047] 5. Relationship between the amount of precious metal supported in the mixture and the slope of the fitted line for the time-dependent change in H2 generation The Pt cluster-supported carbon nitride (Pt loading: 1 wt%) used in the above experiment was mixed with unsupported carbon nitride to prepare a mixture. Various mixtures were prepared by varying the amount of Pt supported in the mixture. A mixture was prepared by mixing the Pt nanoparticle-supported carbon nitride (Pt loading 1 wt%) used in the above experiment with unsupported carbon nitride. Various mixtures were prepared by varying the amount of Pt loaded in the mixture. For each mixture, a dehydrogenation reaction of triethanolamine was carried out. A graph similar to that shown in Figure 7 was drawn, an approximation line was obtained, and the slope of the approximation line was calculated. Figure 9 shows a plot of the slope of the approximate line for the change in the amount of H2 produced over time (per Pt amount) in the dehydrogenation reaction of triethanolamine versus Pt wt%. When Pt cluster-supported carbon nitride was used, the Pt utilization efficiency changed as the amount of Pt in the mixture changed, with the highest efficiency being achieved when the amount was between 0.05 wt% and 0.15 wt% (0.05 mass% and 0.15 mass%). From this experiment, it was confirmed that the amount of precious metal can be optimized and highly activated by further mixing the supported precious metal with unsupported photocatalyst particles.

[0048] 6. Discussion Although precious metals are widely used as cocatalysts for photocatalysts, their reserves are insufficient and they are very expensive. Therefore, to popularize photocatalysts and reduce their costs, it is effective to improve their performance as cocatalysts and reduce their usage. In this example, a photocatalytic material (supported particles) supporting Pt clusters with an atomic number of approximately 15 or less was produced and evaluated using a gas-phase nanocluster synthesis device. The evaluation confirmed that this material was highly active.

[0049] The foregoing examples are for illustrative purposes only and are not to be construed as limiting the invention. While the invention has been described with reference to exemplary embodiments, it is understood that the language used in describing and illustrating the invention is descriptive and exemplary, rather than limiting. As detailed herein, changes may be made within the purview of the appended claims without departing from the scope or spirit of the invention in its form. While the description of the invention has referred to specific structures, materials, and examples herein, it is not intended that the invention be limited to the disclosures therein; rather, the invention is intended to cover all functionally equivalent structures, methods, and uses within the scope of the appended claims.

[0050] The present invention is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the claims of the present invention. [Industrial Applicability]

[0051] The supported particles of the present invention can be used as a photocatalyst in a wide range of applications in a wide range of technical fields, for example, as an organic synthesis reaction catalyst, an exhaust gas catalyst, etc. [Explanation of symbols]

[0052] 1...Support particles 2...Precious metal cluster 3...Photocatalyst particles 4. Inorganic oxides 5...Precious metal particles 6...Protective agent 7...Manufacturing equipment 10...Cluster generation device 11...Chamber 12...cluster growth cells 13...Sputter source 14...liquid nitrogen jacket 15...Control device 16...Pulse power supply for sputtering source 17...First inert gas supply pipe 18...Second inert gas supply pipe 19...Exhaust system 121...Beam outlet 131...Target 132...Anode 133...Magnet unit

Claims

1. A supported particle obtained by supporting a noble metal cluster or a noble metal single atom having an atomic number of 1 to 30 on a photocatalyst particle.

2. The support particles according to claim 1 , wherein the photocatalytic particles are selected from the group consisting of carbon nitride particles and titanium oxide particles.

3. 3. The support particle according to claim 1, wherein no protective agent is bonded to the noble metal cluster or the noble metal single atom.

4. A mixture obtained by mixing the supported particles according to claim 1 or 2 with unsupported photocatalyst particles that do not support the noble metal clusters or the noble metal single atoms.

5. The mixture according to claim 4, wherein the amount of precious metal is 0.05% by mass or more and 0.5% by mass or less, based on 100% by mass of the mixture.

6. A method for producing the supported particles according to claim 1 or 2, comprising: a generating step of generating the noble metal cluster or the noble metal single atom having an atomic number of 1 to 30 by magnetron sputtering; and a supporting step of landing the noble metal clusters or the noble metal single atoms on the photocatalyst particles to support them.

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