Photocatalyst and method for producing hydrogen using the same

Abstract

To provide a useful photocatalyst that can be used to produce hydrogen by splitting water. [Solution] The present invention is a photocatalyst comprising a compound represented by the following general formula (1) and a transition metal complex compound. In the following general formula (1), each R is independently a carbon chain having 1 to 30 carbon atoms, which may contain heteroatoms in the chain, and each R 1 Each of these is independently a carbazolyl group, p is an integer from 1 to 10, each m is independently an integer from 0 to 2, and each n is independently an integer from 0 to 2. TIFF2026132816000018.tif34154

Description

[Technical Field]

[0001] This invention relates to a photocatalyst and a method for producing hydrogen using the same. [Background technology]

[0002] The amount of solar energy that falls on Earth is enormous, and with concerns about the depletion of petroleum resources, the effective utilization of solar energy is being considered. As an example of such effective utilization methods, it is being considered to produce hydrogen by decomposing water by irradiating a photocatalyst with sunlight (see, for example, Patent Document 1). As photocatalysts used in this case, inorganic compounds that have absorption in the visible light region (wavelength: 400nm to 700nm) where the energy level of sunlight is at its peak are known, such as TiO2, LaTiO2, TaON, Y2Ti2O5S2, Rh-doped SrTiO3, ZnRh2O4, Sm2Ti2O2S5, CuAgZnSnS4, etc. These are called inorganic photocatalysts. When these inorganic photocatalysts are irradiated with light, they exhibit oxidation-reduction ability and decompose water into hydrogen and oxygen by oxidation-reduction.

[0003] Incidentally, while these inorganic photocatalysts exhibit redox potential when irradiated with light, as described above, their light absorption for exhibiting this redox potential is not necessarily more efficient than that of organic compounds. This is because most inorganic photocatalysts consist of compounds with electrons in the d-orbitals, and their visible light absorption is based on dd transitions, which inevitably results in a smaller molar extinction coefficient. For this reason, inorganic photocatalysts cannot be said to fully utilize the irradiated light. On the other hand, organic compounds mainly use π-π orbitals. * Transitions and n-π * Although it exhibits strong light absorption based on transitions, its excited form does not show enough redox activity to decompose water. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2023-050965

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a useful photocatalyst that can be used for the production of hydrogen by water decomposition.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a combination of a carbon-bridged p-phenylene vinylene compound and a metal complex compound as a photocatalyst, and have completed the present invention. Note that carbon-bridged p-phenylene vinylene is a compound in which a carbon bridge is formed between a vinylene group and a benzene ring in p-phenylene vinylene, and is a compound having higher rigidity than p-phenylene vinylene. Specifically, the present invention provides the following.

[0007] (1) The present invention is a photocatalyst comprising a compound represented by the following general formula (1) and a transition metal complex compound.

Chemical Formula

[0008] (2) The present invention is also a photocatalyst according to item (1), wherein the compound represented by the general formula (1) is a compound represented by the following general formula (1a-1) or (1a-2). [Chemical formula] (In the above general formula (1a-1), each R is, independently of each other, a carbon chain having 1 to 30 carbon atoms which may contain a hetero atom in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have a substituent, an aryl group having 5 to 30 carbon atoms which may have a substituent, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs are linked to each other to form a cyclic structure, and each R 1 is, independently of each other, a carbazolyl group, -NR 2 2, an alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, or a phenyl group which may have a substituent, and each R 2 is, independently of each other, a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, m is, independently of each other, an integer of 0 to 2, and n is, independently of each other, an integer of 0 to 2. In the above general formula (1a-2), each R is, independently of each other, a carbon chain having 1 to 30 carbon atoms which may contain a hetero atom in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have a substituent, an aryl group having 5 to 30 carbon atoms which may have a substituent, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs are linked to each other to form a cyclic structure, and each R 1 is, independently of each other, a carbazolyl group, -NR 2 2, an alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, or a phenyl group which may have a substituent, and each R 2 is, independently of each other, a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, m is, independently of each other, an integer of 0 to 2, and n is, independently of each other, an integer of

[0009] (3) The present invention is also a photocatalyst as described in item (2), wherein the compound represented by the above general formula (1a-1) is the compound represented by the following general formula (1b-1) or (1b-3), and the compound represented by the above general formula (1a-2) is the compound represented by the following general formula (1b-2). [ka] (In the above general formula (1b-1), Ar is a phenyl group or an aryl group having 5 to 30 carbon atoms which may have substituents, and Ph is a phenyl group, and each R 1 These are, independently, a carbazolyl group and -NR. 2 2. A C1-C30 alkyl group, a C1-C30 alkyloxy group, or a phenyl group which may have substituents, each R 2 Each is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, each is independently an integer from 0 to 2, and each is independently an integer from 0 to 2. In the above general formula (1b-2), Ar is a phenyl group or an aryl group having 5 to 30 carbon atoms which may have substituents, and each R 1 These are, independently, a carbazolyl group and -NR. 2 2. A C1-C30 alkyl group, a C1-C30 alkyloxy group, or a phenyl group which may have substituents, each R 2 Each R is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, each m is independently an integer from 0 to 2, and each n is independently an integer from 0 to 2. In the above general formula (1b-3), each R A Each of these is an alkyl group having 3 to 30 carbon atoms, and each R 1 These are, independently, a carbazolyl group and -NR. 2 2. A C1-C30 alkyl group, a C1-C30 alkyloxy group, or a phenyl group which may have substituents, each R 2 Each of these is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, each of which is independently an integer between 0 and 2, and each of which is independently an integer between 0 and 2.

[0010] (4) The present invention is a photocatalyst according to any one of items (1) to (3), wherein the transition metal complex compound is a compound represented by the following general formula (2a) or (2b), or a specific metal complex compound containing an element selected from the group consisting of Rh, Cr, Ru, Cu, V, Mn, Fe, Co, Ni, Zn, Mo, Tc, Cd, W, Re, Os, and Hg. [ka] (In the above general formula (2a), M is Pt, Pd, or Ni, and L is -OH2, -NH3, or a halogen atom. In the above general formula (2b), M is Ni or Co, and each L is independently -OH2, -NH3, or a halogen atom. Furthermore, the compounds represented by the above general formula (2a) or (2b) contain the necessary counteranions according to their number of positive charges.)

[0011] (5) The present invention is also a photocatalyst as described in item (4), wherein the above-mentioned specific metal complex compound is a rhodium(II) acetate dimer.

[0012] (6) The present invention is also a method for producing hydrogen, characterized by generating hydrogen from water by a photoreaction using ultraviolet or visible light in the presence of a photocatalyst described in any one of items (1) to (5). [Effects of the Invention]

[0013] According to the present invention, a useful photocatalyst is provided that can be used to produce hydrogen by the decomposition of water. [Modes for carrying out the invention]

[0014] The following describes one embodiment of the photocatalyst of the present invention and one embodiment of a method for producing hydrogen. It should be noted that the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the present invention.

[0015] <Photocatalyst> First, the photocatalyst of the present invention will be described. The photocatalyst of the present invention comprises a compound represented by the following general formula (1) and a transition metal complex compound. The compound represented by the following general formula (1) has a π-conjugated structure consisting of a carbon-bridged p-phenylenevinylene skeleton. This p-phenylenevinylene skeleton is bridged with carbon atoms so as to form a five-membered ring in the vinylene portion, and this bridge restricts the free rotation of the vinylene portion. As a result, twisting of the π-conjugated system is suppressed, and electron movement in the π-conjugated system becomes smooth. In addition, this p-phenylenevinylene skeleton can strongly absorb visible light, and when it enters an excited state due to this absorption, combined with the smooth electron movement as described above, it transfers energy to the central metal of the nearby transition metal complex compound. The central metal of the transition metal complex compound that receives the energy exerts its redox ability to decompose surrounding water molecules and produce hydrogen. Thus, in the photocatalyst of the present invention, the compound represented by the following general formula (1) plays the role of absorbing light energy, and the transition metal complex compound plays the role of decomposing water molecules through oxidation-reduction action using that energy, thereby decomposing water molecules and generating hydrogen under light irradiation. Next, these compounds will be described.

[0016] [ka]

[0017] In the general formula (1) above, each R is independently a carbon chain having 1 to 30 carbon atoms, which may contain heteroatoms in the chain; a cycloalkyl group having 4 to 20 carbon atoms, which may have substituents; an aryl group having 5 to 30 carbon atoms, which may have substituents; a trialkylsilyl group; an arylalkyl group; or two adjacent Rs linked together to form a cyclic structure. These Rs are bonded to the carbon atoms forming the bridging described above, as can be understood from general formula (1), and are bulky substituents. These bulky substituents, Rs, protrude above and below the π-conjugated system of the compound, covering it and thus suppressing attack of chemical species on the π-conjugated system. As a result, compounds represented by general formula (1) exhibit high thermal and chemical stability. Note that "each R is independently" means that the multiple Rs included in general formula (1) are determined independently, and they may be the same as or different from each other. The expression "each is independently" is used frequently below, but in all cases it is interpreted in the same way.

[0018] A carbon chain having 1 to 30 carbon atoms, which may contain heteroatoms, is a linear or branched chain-like group containing 1 to 30 carbon atoms, and this chain-like group is a monovalent group that may or may not contain heteroatoms. Examples of heteroatoms include oxygen atoms, sulfur atoms, nitrogen atoms, etc. One or more of these heteroatoms may be included; for example, a polyoxyethylene group containing multiple oxygen atoms may be included. Preferably, the carbon chain contains 6 to 30 carbon atoms.

[0019] A cycloalkyl group having 4 to 20 carbon atoms that may have substituents is a cycloalkyl group that may or may not have substituents, and in the case of substituents, the hydrogen atoms of the cycloalkyl group are replaced by substituents. Examples of such substituents include alkyl groups having 1 to 12 carbon atoms, arylalkyl groups, alkylarylalkyl groups, and the like.

[0020] An aryl group having 5 to 30 carbon atoms that may have substituents is an aryl group that may or may not have substituents, and in the case of substituents, the hydrogen atoms of the aryl group are replaced by substituents. Examples of such substituents include alkyl groups having 1 to 12 carbon atoms. Examples of aryl groups that may have substituents include phenyl groups, alkylphenyl groups, arylalkyl groups, and alkylarylalkyl groups, and among alkylphenyl groups, the 4-octylphenyl group is a preferred example.

[0021] Arylalkyl groups are groups that have an aromatic ring at the end of an alkylene chain, such as the benzyl group. The alkylene chain in this case can have approximately 1 to 20 carbon atoms. Examples of aromatic rings include phenyl, naphthyl, fluorenyl, and carbazolyl groups. Alkylarylalkyl groups are groups that have an aromatic ring sandwiched between two alkyl chains (an alkylene chain and an alkyl group). The alkyl chain in this case can have approximately 1 to 20 carbon atoms. Examples of aromatic rings include phenyl, naphthyl, fluorenyl, and carbazolyl groups.

[0022] When two adjacent R atoms are linked to form a cyclic structure, this cyclic structure, together with the five-membered ring in general formula (1), forms a spirostructure. The cyclic structure may be an antilipid ring or an aromatic ring, may contain heteroatoms such as nitrogen, sulfur, or oxygen, or may form a fused ring. Examples of such cyclic structures include fluorene rings and cycloalkane rings with 4 to 20 carbon atoms. For example, if the cyclic structure is a fluorene ring, the two adjacent R atoms form a spirofluorenyl group, and if the cyclic structure is a cycloalkane ring such as a cyclopentane ring or a cyclohexane ring, the two adjacent R atoms become spirocycloalkyl groups such as a spirocyclopentyl group or a spirocyclohexyl group. When the cyclic structure is a fluorene ring, its fused five-membered ring and the five-membered ring in general formula (1) form a spirostructure. Furthermore, "two adjacent R atoms" means that the two R atoms are bonded to the same carbon atom.

[0023] In the above general formula (1), each R 1 These are, independently, a carbazolyl group and -NR. 2 2. C1-C30 alkyl groups, C1-C30 alkyloxy groups, and optionally substituted phenyl groups. These alkyl and alkyloxy groups may be linear or branched. The optionally substituted phenyl group may be a substituted phenyl group or an unsubstituted phenyl group. Examples of substituents include C1-C12 alkyl groups, arylalkyl groups, alkylarylalkyl groups, etc. -NR 2 R in 2 2 Each of these is independently either a hydrogen atom or an alkyl group having 1 to 30 carbon atoms.

[0024] In the above general formula (1), p is an integer between 1 and 10, preferably between 1 and 5, more preferably between 1 and 3, and particularly preferably 2. Each m is an independent integer between 0 and 2, and each n is an independent integer between 0 and 2.

[0025] Preferred examples of compounds represented by the above general formula (1) include those represented by the following general formulas (1a-1) and (1a-2). The following general formula (1a-1) is obtained by specifying p to 2 in the above general formula (1), and the following general formula (1a-2) is obtained by specifying p to 1 in the above general formula (1).

[0026] [ka]

[0027] In the above general formula (1a-1), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked to each other to form a cyclic structure, and each R 1 These are, independently, a carbazolyl group and -NR. 2 2. A C1-C30 alkyl group, a C1-C30 alkyloxy group, or a phenyl group which may have substituents, each R 2 Each of these is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, each of which is independently an integer between 0 and 2, and each of which is independently an integer between 0 and 2. These are the same as those in the general formula (1) above, so a detailed explanation will be omitted.

[0028] In the above general formula (1a-2), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked to each other to form a cyclic structure, and each R 1 These are, independently, a carbazolyl group and -NR. 22. A C1-C30 alkyl group, a C1-C30 alkyloxy group, or a phenyl group which may have substituents, each R 2 Each of these is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, each of which is independently an integer from 0 to 2, and each of which is independently an integer from 0 to 2. These are the same as those in the general formula (1) above, so a detailed explanation will be omitted.

[0029] Preferred examples of compounds represented by the above general formula (1a-1) include those represented by the following general formulas (1b-1) or (1b-3).

[0030] [ka]

[0031] In the above general formula (1b-1), Ar is a phenyl group or an aryl group having 5 to 30 carbon atoms which may have substituents, and Ph is a phenyl group, and each R 1 These are, independently, a carbazolyl group and -NR. 2 2. A C1-C30 alkyl group, a C1-C30 alkyloxy group, or a phenyl group which may have substituents, each R 2 Each of these is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, each of which is independently an integer between 0 and 2, and each of which is independently an integer between 0 and 2. These are the same as those in the general formula (1) above, so a detailed explanation will be omitted.

[0032] In the above general formula (1b-3), each R A Each of these is an alkyl group having 3 to 30 carbon atoms, and each R 1 These are, independently, a carbazolyl group and -NR. 2 2. A C1-C30 alkyl group, a C1-C30 alkyloxy group, or a phenyl group which may have substituents, each R 2Each of the elements is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, each of the elements is independently an integer from 0 to 2, and each of the elements is independently an integer from 0 to 2. A Preferably, alkyl groups having 4 to 12 carbon atoms are used, and among these, n-butyl groups are particularly preferred. Other details are the same as those in general formula (1) above, so a detailed explanation is omitted.

[0033] [ka]

[0034] In the above general formula (1b-2), Ar is a phenyl group or an aryl group having 5 to 30 carbon atoms, which may have substituents, and each R 1 These are, independently, a carbazolyl group and -NR. 2 2. A C1-C30 alkyl group, a C1-C30 alkyloxy group, or a phenyl group which may have substituents, each R 2 Each of these is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, each of which is independently an integer from 0 to 2, and each of which is independently an integer from 0 to 2. These are the same as those in the general formula (1) above, so a detailed explanation will be omitted.

[0035] The synthesis methods for the compounds represented by the above general formula (1) are publicly known in various patent documents and scientific papers, so these compounds can be obtained by performing synthesis by referring to such publicly known information. For example, for the compounds represented by general formulas (1b-1) to (1b-3), those synthesized according to the methods described in J.Am.Chem.Soc.2012,134,19254-19259, JP 2011-32197, JP 2023-160215, etc., can be used.

[0036] In transition metal complex compounds, the compound represented by the above general formula (1) becomes excited upon light irradiation, and then receives this energy from the compound represented by the above general formula (1). This energy is then used in a redox reaction to decompose surrounding water molecules and produce hydrogen. This redox reaction occurs at the central metal contained in the transition metal complex compound. Preferred examples of transition metal complex compounds include the compounds represented by the following general formulas (2a) or (2b), or the specific metal complex compounds described later, but the transition metal complex compounds in the present invention are not limited to these.

[0037] [ka]

[0038] In the general formula (2a) above, M is Pt, Pd, or Ni. That is, the central metal M is Pt, Pd, or Ni that has a planar four-coordinate structure. In this case, the terpyridine skeleton shown in general formula (2a) becomes a tridentate ligand for the central metal M. L is a monodentate ligand that coordinates to the remaining coordination sites of M, and is -OH2 (aqua ligand), -NH3 (ammine ligand), or a halogen atom. Among these, a halogen atom, particularly Cl, is preferred for L.

[0039] In the general formula (2b) above, M is Ni or Co. That is, the central metal M is Ni or Co that takes on a hexa-coordinate structure (octahedral structure). In this case, the terpyridine skeleton shown in general formula (2b) becomes a tridentate ligand for the central metal M. L is a monodentate ligand that coordinates to the remaining coordination sites of M, and can be -OH2 (aqua ligand), -NH3 (ammine ligand), or a halogen atom. Among these, -OH2 and halogen atoms are preferred for L, and among halogen atoms, Cl is preferred.

[0040] Here, Pt, Pd, Ni, and Co, which are the central metals of the complex in the general formulas (2a) and (2b) above, are all known to be capable of generating hydrogen from water when their metal complexes are used as photocatalysts.

[0041] In addition, depending on the type of central metal and the combination of ligand L bonded to it, the entire compound represented by general formula (2a) or general formula (2b) may be a cation. In such cases, these compounds will contain appropriate counteranions according to their number of positive charges. Although these counteranions are not described in general formula (2a) or general formula (2b) above, photocatalysts containing such counteranions are of course also included in the present invention.

[0042] Compounds represented by the above general formulas (2a) and (2b) can be obtained by acquiring commercially available 2,2':6',2''-terpyridine, coordinating it with the metal element corresponding to M using a known method, and, if necessary, replacing the resulting counteranion with a hexafluorophosphate anion or the like.

[0043] Examples of specific metal complex compounds include those containing an element selected from the group consisting of Rh, Cr, Ru, Cu, V, Mn, Fe, Co, Ni, Zn, Mo, Tc, Cd, W, Re, Os, and Hg as the central metal. Since various types of these specific metal complex compounds are commercially available, they can be obtained and used as appropriate. A rhodium(II) acetate dimer is a preferred example of such a specific metal complex compound.

[0044] As already mentioned, the photocatalyst of the present invention is a combination of the compound represented by the above general formula (1) and a transition metal complex compound. The photocatalyst of the present invention, for example, is dissolved in an aprotic polar solvent such as dimethylformamide (DMF), and when irradiated with light in the presence of a sacrificial reagent and water, it decomposes water and generates hydrogen. In this case, the concentration of the compound represented by general formula (1) is approximately 1 to 100 μmol / L, and the concentration of the transition metal complex compound is approximately 0.1 to 200 μmol / L. The concentration of the sacrificial reagent at this time can be approximately 1 to 20 vol%.

[0045] The light source used to exert the photocatalytic effect is not particularly limited, as long as it contains light of wavelengths that can be absorbed by the compound represented by the general formula (1) above. Examples of such light sources include sunlight, xenon lamps, and LED lamps.

[0046] As sacrificial reagents, any known sacrificial reagents used in hydrogen production reactions can be listed without particular limitation, but among these, amine compounds such as triethylamine are preferred.

[0047] Furthermore, the form of the photocatalyst of the present invention is not particularly limited. Examples of such forms include, as described above, a solution containing the compound represented by general formula (1) and the compound represented by general formula (2a) or (2b), or a form in which these compounds are supported on a carrier such as silica.

[0048] <Methods for generating hydrogen> Another method of producing hydrogen, characterized by generating hydrogen from water through a photoreaction using ultraviolet or visible light in the presence of the above-mentioned photocatalyst, is also part of the present invention. As this has already been explained, a further explanation will be omitted here. [Examples]

[0049] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the following examples.

[0050] ·Compound 10 [ka]

[0051] Compound 10 was synthesized according to the method described in Japanese Patent Publication No. 2011-32197. This compound 10 corresponds to the compound represented by the above general formula (1). In the structural formula of compound 10, "Ph" represents a phenyl group.

[0052] Synthesis of compound 12 [ka]

[0053] Separately synthesized cis-[PtCl2(dmso)2] (182 mg, 0.430 mmol) was dissolved in acetonitrile (MeCN; 20 mL), and then 2,2':6',2''-terpyridine (Tpy; 101 mg, 0.433 mmol, 1.0 equivalent) was added and the mixture was stirred at room temperature for 1 day. The resulting red powder was filtered, washed five times with 10 mL of MeCN, and vacuum-dried to obtain crude compound 11, a reddish-orange powder (yield 173 mg). This crude compound 11 (80.0 mg) was dissolved in N,N-dimethylformamide (DMF; 20 mL) while heating. Meanwhile, methanol (MeOH; 6 mL) was added to ammonium hexafluorophosphate (NH4PF6; 2.45 g, 15.0 mmol, large excess), and the residue was removed by filtration to prepare a MeOH solution of NH4PF6. The entire volume of this solution was added to the DMF solution of crude compound 11 described above, and the mixture was stirred at 50°C for 17 hours. After the reaction mixture was allowed to cool to room temperature, 200 mL of diethyl ether was added, and the yellow powder was filtered and washed five times with 5 mL of MeOH. The hot MeCN-soluble component was eluted from this powder (7 × 10 mL), and the eluate was evaporated to dryness under reduced pressure to obtain an orange solid. This solid was dissolved in 1 mL of DMF, and after adding 15 mL of MeOH, the resulting precipitate was filtered, washed three times with 2 mL of MeOH, and vacuum dried to obtain compound 12 as a yellow solid (yield 54.3 mg, yield 44.8%). The target complex was identified by absorption spectroscopy, and the purity of the sample was confirmed by CHN elemental analysis. UV-vis(DMF) λ max (ε M / M -1 cm -1 ) 394(2230),379(2577),352(10004),334(14476),320(11144)sh,285(22616),275(20429)sh nm. CHN elem. anal. Calcd for C 15 H 11 ClF6N3PPt:C,29.59;H,1.82;N,6.90. Found:C,29.86;H,1.96;N,6.95.

[0054] [Hydrogen production from water using a mixture of compound 10 and compound 12 as a photocatalyst 1 (compound 12: 20 μM, 24 hours)] Compound 10 (0.133 mg), Compound 12 (0.122 mg), triethylamine (TEA; 0.500 mL), and ultrapure water (0.500 mL) were added to DMF to prepare a total volume of 10 mL of sample solution (Compound 10: 10 μmol / L, Compound 12: 20 μmol / L, TEA: 5.0 vol% (0.36 mol / L), Ultrapure water: 5.0 vol%). The sample solution was frozen and degassed using a Schlenk tube, and then transferred to a photoreaction cell (manufactured by Makuhari Chemical Glass Co., Ltd.) containing a stirring bar in a glove box filled with argon. The photoreaction cell containing the sample solution was then attached to a closed circulation system for photocatalytic reactions with a single automated gas sampler (manufactured by Makuhari Chemical Glass Co., Ltd.), and the headspace was depressurized and filled with argon four times until the headspace was finally subjected to an argon atmosphere of 519.3 Torr. Subsequently, the reaction was allowed to proceed for 24 hours at room temperature (25°C) by irradiating the sample solution with light using a xenon lamp (Optical ModuleX, output: 500W) equipped with a long-pass filter (transmission wavelength: >400nm) while stirring the sample solution with a magnetic stirrer. The generated hydrogen was quantified by calibration curve method by directly introducing the headspace gas, separated via an automated gas sampler, into a gas chromatograph (GC-8A, Shimadzu Corporation, mobile phase: argon) equipped with a stainless steel packed column (Shinwa Chemical Co., Ltd., stationary phase: molecular sieve 5A, 3.0 mm I.D. × 3.0 m × 2) and a thermal conductivity detector. As a result, the amount of hydrogen generated after 24 hours was 13 μmol. Furthermore, the turnover rate (TON) and turnover frequency (TOF) were calculated based on the hydrogen generation data obtained in this way. As a result, the catalytic turnover number after 24 hours was 64, and the maximum catalytic turnover frequency (TOF) was 2.7h at 22 hours. -1 That was the case.

[0055] [Hydrogen production from water using a mixture of compound 10 and compound 12 as a photocatalyst 2 (compound 12: 20 μM, 100 hours)] Compound 10 (0.134 mg), Compound 12 (0.124 mg), triethylamine (TEA; 0.500 mL), and ultrapure water (0.500 mL) were added to DMF to prepare a total volume of 10 mL of sample solution (Compound 10: 10 μmol / L, Compound 12: 20 μmol / L, TEA: 5.0 vol% (0.36 mol / L), Ultrapure water: 5.0 vol%). The sample solution was freeze-degassed using a Schlenk tube, and then transferred to a photoreaction cell (manufactured by Makuhari Chemical Glass Co., Ltd.) containing a stirring bar in a glove box filled with argon. The photoreaction cell containing the sample solution was then attached to a closed circulation system for photocatalytic reactions with a single automated gas sampler (manufactured by Makuhari Chemical Glass Co., Ltd.), and the headspace was depressurized and filled with argon four times until the headspace was finally subjected to an argon atmosphere of 510.9 Torr. Subsequently, the reaction was allowed to proceed for 100 hours at room temperature (25°C) by irradiating the sample solution with light using a xenon lamp (Optical ModuleX, output: 500W) equipped with a long-pass filter (transmission wavelength: >400nm) while stirring the sample solution with a magnetic stirrer. The generated hydrogen was quantified by calibration curve by directly introducing the headspace gas, separated via an automated gas sampler, into a gas chromatograph (GC-8A, Shimadzu Corporation, mobile phase: argon) equipped with a stainless steel packed column (Shinwa Chemical Co., Ltd., stationary phase: molecular sieve 5A, 3.0 mm I.D. × 3.0 m × 2) and a thermal conductivity detector. As a result, the amount of hydrogen generated after 100 hours was 45 μmol. Furthermore, based on the hydrogen production data obtained in this way, the turnover speed (TON) and turnover frequency (TOF) were calculated. As a result, the turnover speed after 100 hours was 220, and the maximum turnover frequency (TOF) was 3.5h at 18 hours. -1 That was the case.

[0056] [Hydrogen production from water using a mixture of compound 10 and compound 12 as a photocatalyst 3 (compound 12: 2 μM, 100 hours)] Compound 10 (0.140 mg), a DMF solution containing 0.132 mg of Compound 12 in a total volume of 10 mL (0.923 mL), triethylamine (TEA; 0.500 mL), and ultrapure water (0.500 mL) were added to DMF to prepare a total volume of 10 mL of sample solution (Compound 10: 10 μmol / L, Compound 12: 2.0 μmol / L, TEA: 5.0 vol% (0.36 mol / L), Ultrapure water: 5.0 vol%). The sample solution was frozen and degassed using a Schlenk tube, and then transferred to a photoreaction cell (manufactured by Makuhari Chemical Glass Co., Ltd.) containing a stirring bar in a glove box filled with argon. The photoreaction cell containing the sample solution was mounted in a closed-circulation system for photocatalytic reactions with a single automated gas sampler (manufactured by Makuhari Chemical Glass Co., Ltd.). The headspace was then depressurized and filled with argon four times until the headspace was finally subjected to an argon atmosphere of 516.5 Torr. Subsequently, the reaction was allowed to proceed at room temperature (25°C) for 100 hours while stirring the sample solution with a magnetic stirrer, by irradiating the sample solution with light using a xenon lamp (Optical ModuleX, output: 500W) equipped with a long-pass filter (transmission wavelength: >400nm) (manufactured by Ushio Inc.). The generated hydrogen was quantified using a calibration curve method by directly introducing the headspace gas, separated via an automatic gas sampler, into a gas chromatograph (Shimadzu Corporation GC-8A, mobile phase: argon) equipped with a stainless steel packed column (Shinwa Chemical Co., Ltd., stationary phase: molecular sieve 5A, 3.0 mm I.D. × 3.0 m × 2) and a thermal conductivity detector. The results showed that the amount of hydrogen generated after 100 hours was 13 μmol. Furthermore, the turnover number (TON) and turnover frequency (TOF) were calculated based on the hydrogen generation data obtained. The results showed that the turnover number after 100 hours was 633, and the maximum turnover frequency (TOF) was 20h at 3 hours. -1 That was the case.

[0057] [Hydrogen production from water using a mixture of compound 10 and compound 12 as a photocatalyst 4 (compound 12: 0.2 μM, 100 hours)] Compound 10 (0.144 mg), a DMF solution containing 0.160 mg of Compound 12 in a total volume of 10 mL (76.1 μL), triethylamine (TEA; 0.500 mL), and ultrapure water (0.500 mL) were added to DMF to prepare a total volume of 10 mL of sample solution (Compound 10: 10 μmol / L, Compound 12: 0.20 μmol / L, TEA: 5.0 vol% (0.36 mol / L), Ultrapure water: 5.0 vol%). The sample solution was frozen and degassed using a Schlenk tube, and then transferred to a photoreaction cell (manufactured by Makuhari Chemical Glass Co., Ltd.) containing a stirring bar in a glove box filled with argon. After attaching the photoreaction cell containing the sample solution to a closed-circulation system for photocatalytic reactions with a single automated gas sampler (manufactured by Makuhari Chemical Glass Co., Ltd.), the headspace was depressurized and filled with argon four times until the headspace was finally subjected to an argon atmosphere of 515.0 Torr. Subsequently, the reaction was allowed to proceed at room temperature (25°C) for 100 hours while stirring the sample solution with a magnetic stirrer, by irradiating the sample solution with light using a xenon lamp (manufactured by Ushio Inc., Optical ModuleX, output: 500W) equipped with a long-pass filter (transmission wavelength: >400nm). The generated hydrogen was quantified using a calibration curve method by directly introducing the headspace gas, separated via an automatic gas sampler, into a gas chromatograph (Shimadzu Corporation GC-8A, mobile phase: argon) equipped with a stainless steel packed column (Shinwa Chemical Co., Ltd., stationary phase: molecular sieve 5A, 3.0 mm I.D. × 3.0 m × 2) and a thermal conductivity detector. The results showed that the amount of hydrogen generated after 100 hours was 1.2 μmol. Furthermore, the turnover number (TON) and turnover frequency (TOF) were calculated based on the hydrogen generation data obtained. The results showed that the turnover number after 100 hours was 605, and the maximum turnover frequency (TOF) was 16h at 8 hours. -1 That was the case.

[0058] [Hydrogen production from water using a mixture of compound 10 and rhodium(II) acetate dimer as a photocatalyst] Compound 10 (0.278 mg), a tetrahydrofuran (THF) solution containing 0.294 mg of rhodium(II) acetate dimer in a total volume of 10 mL (0.752 mL), triethylamine (TEA; 0.500 mL), and ultrapure water (3.000 mL) were added to the THF to prepare a total volume of 10 mL of sample solution (Compound 10: 20 μmol / L, Rhodium(II) acetate dimer: 5.0 μmol / L, TEA: 5.0 vol% (0.36 mol / L), Ultrapure water: 30.0 vol%). The sample solution was frozen and degassed using a Schlenk tube, and then transferred to a photoreaction cell (manufactured by Makuhari Chemical Glass Co., Ltd.) containing a stirring bar in a glove box filled with argon. The photoreaction cell containing the sample solution was mounted in a closed-circulation system for photocatalytic reactions with a single automated gas sampler (manufactured by Makuhari Rikagaku Glass Manufacturing Co., Ltd.). The headspace was then depressurized and filled with argon four times until the headspace was finally subjected to an argon atmosphere of 555.9 Torr. Subsequently, the reaction was allowed to proceed at room temperature (25°C) for 24 hours while stirring the sample solution with a magnetic stirrer, by irradiating the sample solution with light using a xenon lamp (manufactured by Ushio Inc., Optical ModuleX, output: 500W) equipped with a long-pass filter (transmission wavelength: >400nm). The generated hydrogen was quantified using a calibration curve method by directly introducing the headspace gas, separated via an automated gas sampler, into a gas chromatograph (Shimadzu Corporation GC-8A, mobile phase: argon) equipped with a stainless steel packed column (Shinwa Chemical Co., Ltd., stationary phase: molecular sieve 5A, 3.0 mm I.D. × 3.0 m × 2) and a thermal conductivity detector, every hour from the start of light irradiation. As a result, the amount of hydrogen generated after 24 hours was 3.3 μmol. Furthermore, the turnover number (TON) and turnover frequency (TOF) were calculated based on the hydrogen generation data obtained in this way. As a result, the turnover number after 24 hours was 65, and the maximum turnover frequency (TOF) was 6.6 h at 2 hours. -1 That was the case.

[0059] ·Compound 20 [ka] Compound 20 was synthesized according to the method described in J.Am.Chem.Soc.2012,134,19254-19259. This compound 20 corresponds to the compound represented by the general formula (1) above. Note that "Ph" in the structural formula of compound 20 represents a phenyl group.

[0060] [Hydrogen production from water using a photocatalyst mixture of compound 20 and rhodium(II) acetate dimer] Compound 20 (14 mg) was dissolved in dichloromethane (CH2Cl2; 7.300 mL), and the resulting solution (1 mL) was added to a 10 mL volumetric flask and dried. Then, the solution was made up with THF to a total volume of 10 mL to prepare a solution of compound 20. This solution (1 mL), a THF solution containing 0.300 mg of rhodium(II) acetate dimer in a total volume of 10 mL (0.737 mL), triethylamine (TEA; 0.500 mL), and ultrapure water (3.000 mL) were added to THF to prepare a sample solution of a total volume of 10 mL (compound 20: 20 μmol / L, rhodium(II) acetate dimer: 5.0 μmol / L, TEA: 5.0 vol% (0.36 mol / L), ultrapure water: 30.0 vol%). The sample solution was frozen and degassed using a Schlenk tube, and then transferred to a photoreaction cell (manufactured by Makuhari Chemical Glass Co., Ltd.) containing a stirring bar in a glove box filled with argon. The photoreaction cell containing the sample solution was then attached to a closed circulation system for photocatalytic reactions with a single automated gas sampler (manufactured by Makuhari Chemical Glass Co., Ltd.), and the headspace was depressurized and filled with argon four times until the headspace was finally subjected to an argon atmosphere of 553.2 Torr. Subsequently, the reaction was allowed to proceed for 24 hours at room temperature (25°C) by irradiating the sample solution with light using a xenon lamp (manufactured by Ushio Inc., Optical ModuleX, output: 500W) equipped with a long-pass filter (transmission wavelength: >400nm) while stirring the sample solution with a magnetic stirrer. The generated hydrogen was quantified using a calibration curve method by directly introducing the headspace gas, separated via an automated gas sampler, into a gas chromatograph (Shimadzu Corporation GC-8A, mobile phase: argon) equipped with a stainless steel packed column (Shinwa Chemical Co., Ltd., stationary phase: molecular sieve 5A, 3.0 mm I.D. × 3.0 m × 2) and a thermal conductivity detector, every hour from the start of light irradiation. As a result, the amount of hydrogen generated after 24 hours was 5.1 μmol. Furthermore, the turnover number (TON) and turnover frequency (TOF) were calculated based on the hydrogen generation data obtained in this way. As a result, the turnover number after 24 hours was 102, and the maximum turnover frequency (TOF) was 12h at 2 hours. -1 That was the case.

[0061] ·Compound 30 [ka] Compound 30 (COPV2(Bu) in the aforementioned Japanese Patent Publication No. 2023-160215) was synthesized according to the method described in Japanese Patent Publication No. 2023-160215. This compound 30 corresponds to the compound represented by the above general formula (1). In the structural formula of compound 30, "Bu" represents an n-butyl group.

[0062] [Hydrogen production from water using a photocatalyst mixture of compound 30 and compound 12] Compound 30 (0.078 mg), a DMF solution containing 0.135 mg of Compound 12 in a total volume of 10 mL (0.902 mL), triethylamine (TEA; 0.500 mL), and ultrapure water (0.500 mL) were added to DMF to prepare a total volume of 10 mL of sample solution (Compound 30: 10 μmol / L, Compound 12: 2.0 μmol / L, TEA: 5.0 vol% (0.36 mol / L), Ultrapure water: 5.0 vol%). The sample solution was frozen and degassed using a Schlenk tube, and then transferred to a photoreaction cell (manufactured by Makuhari Chemical Glass Co., Ltd.) containing a stirring bar in a glove box filled with argon. The photoreaction cell containing the sample solution was mounted in a closed-circulation system for photocatalytic reactions with a single automated gas sampler (manufactured by Makuhari Rikagaku Glass Co., Ltd.). The headspace was then depressurized and filled with argon four times until the headspace was finally subjected to an argon atmosphere of 518.7 Torr. Subsequently, the reaction was allowed to proceed at room temperature (25°C) for 100 hours by irradiating the sample solution with light using a xenon lamp (Optical ModuleX, output: 500W) equipped with a long-pass filter (transmission wavelength: >400nm) while stirring the sample solution with a magnetic stirrer. The generated hydrogen was quantified using a calibration curve method by directly introducing the headspace gas, separated via an automatic gas sampler, into a gas chromatograph (Shimadzu Corporation GC-8A, mobile phase: argon) equipped with a stainless steel packed column (Shinwa Chemical Co., Ltd., stationary phase: molecular sieve 5A, 3.0 mm I.D. × 3.0 m × 2) and a thermal conductivity detector. The results showed that the amount of hydrogen generated after 100 hours was 1.5 μmol. Furthermore, the turnover number (TON) and turnover frequency (TOF) were calculated based on the hydrogen generation data obtained. The results showed that the turnover number after 100 hours was 76, and the maximum turnover frequency (TOF) was 1.9 h at 17 hours. -1 That was the case.

[0063] As described above, it can be understood that the photocatalyst of the present invention generates hydrogen by decomposing water upon light irradiation.

Claims

1. A photocatalyst comprising a compound represented by the following general formula (1) and a transition metal complex compound. 【Chemistry 1】 (In the above general formula (1), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked to each other to form a cyclic structure, each R １ These are, independently, a carbazolyl group and an -NR ２ ２ , an alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, or a phenyl group which may have substituents, each R ２ Each of these is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, p is an integer from 1 to 10, each m is independently an integer from 0 to 2, and each n is independently an integer from 0 to 2.

2. The photocatalyst according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (1a-1) or (1a-2). 【Chemistry 2】 (In the above general formula (1a-1), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain a hetero atom in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have a substituent, an aryl group having 5 to 30 carbon atoms which may have a substituent, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs are linked to each other to form a cyclic structure, and each R １ is independently a carbazolyl group, -NR ２ ２ , an alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, or a phenyl group which may have a substituent, and each R ２ is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, m is independently an integer of 0 to 2, and n is independently an integer of 0 to 2. In the above general formula (1a-2), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain a hetero atom in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have a substituent, an aryl group having 5 to 30 carbon atoms which may have a substituent, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs are linked to each other to form a cyclic structure, and each R １ is independently a carbazolyl group, -NR ２ ２ , an alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, or a phenyl group which may have a substituent, and each R ２ is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, m is independently an integer of 0 to 2, and n is independently an integer of 0 to 2.).

3. The photocatalyst according to claim 2, wherein the compound represented by the general formula (1a-1) is the compound represented by the following general formula (1b-1) or (1b-3), and the compound represented by the general formula (1a-2) is the compound represented by the following general formula (1b-2). 【Transformation 3】 (In the above general formula (1b-1), Ar is a phenyl group or an aryl group having 5 to 30 carbon atoms which may have substituents, and Ph is a phenyl group, and each R １ These are, independently, a carbazolyl group and an -NR ２ ２ , an alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, or a phenyl group which may have substituents, each R ２ Each is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, each is independently an integer from 0 to 2, and each is independently an integer from 0 to 2. In the above general formula (1b-2), Ar is a phenyl group or an aryl group having 5 to 30 carbon atoms which may have substituents, and each R １ These are, independently, a carbazolyl group and an -NR ２ ２ , an alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, or a phenyl group which may have substituents, each R ２ Each R is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, each m is independently an integer from 0 to 2, and each n is independently an integer from 0 to 2. In the above general formula (1b-3), each R Ａ Each of these is an alkyl group having 3 to 30 carbon atoms, and each R １ These are, independently, a carbazolyl group and an -NR ２ ２ , an alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, or a phenyl group which may have substituents, each R ２ Each of these is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, each of which is independently an integer from 0 to 2, and each of which is independently an integer from 0 to 2.

4. The photocatalyst according to claim 1, wherein the transition metal complex compound is a compound represented by the following general formula (2a) or (2b), or a specific metal complex compound containing an element selected from the group consisting of Rh, Cr, Ru, Cu, V, Mn, Fe, Co, Ni, Zn, Mo, Tc, Cd, W, Re, Os, and Hg. 【Chemistry 4】 (In the above general formula (2a), M is Pt, Pd or Ni, and L is -OH) ２ , -NH ３ or halogen atoms. In the above general formula (2b), M is Ni or Co, and each L is independently -OH ２ , -NH ３ Alternatively, it may be a halogen atom. Furthermore, the compounds represented by the above general formula (2a) or (2b) contain the necessary counteranions according to their number of positive charges.

5. The photocatalyst according to claim 4, wherein the specified metal complex compound is a rhodium(II) acetate dimer.

6. A method for producing hydrogen, characterized by generating hydrogen from water by a photoreaction using ultraviolet or visible light in the presence of a photocatalyst according to any one of claims 1 to 5.

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