Electrochemical reduction of carbon dioxide catalyzed by polyoxometalates

Abstract

According to the present disclosure, there is provided a polyoxometalate compound represented by the following formula (I) or a solvate thereof, and a method for electrochemically reducing carbon dioxide (CO2) using the same. (Q) n [XM a M b M c (L a )(L b )(L c )W9O 37 ] (I)

Description

[Technical Field]

[0001] This disclosure relates to a polyoxometalate compound represented by the following formula (I) or its solvate, and a method for electrochemically reducing carbon dioxide (CO2) using the same. (Q) n [XM a M b M c (L a )(L b )(Lc)W9O 37 ] (I) [Background technology]

[0002] The fixation and further utilization of gaseous carbon dioxide is one of nature's most important achievements and one of the most important objectives in environmental and energy-related chemistry. Carbon dioxide is the main greenhouse gas produced by human activities, and atmospheric carbon dioxide concentrations exceed the 400 ppm threshold. The increasing emission of carbon dioxide (CO2) necessitates methods for converting carbon dioxide into useful chemicals (Cokoja, M.; Bruckmeier, C.; Rieger, B.; Herrmann, WA; Kuhn, FE Transformation of Carbon Dioxide with Homogeneous Transition-Metal Catalysts: A Molecular Solution to a Global Challenge? Angew. Chemie - Int. Ed. 2011, 50, 8510-8537). One of the most studied conversion methods involves converting CO2 to carbon monoxide by photochemical or electrochemical reduction, thereby generating versatile intermediates for further known conversions into usable products. Other reduction products of interest include methanol and CC-bonded compounds such as ethanol.Unfortunately, the direct electro-assisted reduction of CO2 on bare electrodes is a kinetically slow process characterized by large overpotentials resulting from the multi-electron nature of the reaction and the fundamental requirements for the rearrangement of the CO2 molecular structure (Mikkelsen, M.; Jorgensen, M.; Krebs, FC The Teraton Challenge. A Review of Fixation and Transformation of Carbon Dioxide. Energy Environ. Sci. 2010, 3, 43-81; Appel, AM; Bercaw, JE; Bocarsly, AB; Dobbek, H.; Dubois, DL; Dupuis, M.; Ferry, JG; Fujita, E.; Hille, R.; Kenis, PJA; Kerfeld, CA; Morris, RH; Peden, CHF; Portis, AR; Ragsdale, SW; Rauchfuss, TB; Reek, JNH; Seefeldt, LC; Thauer, RK; Waldrop, GL Frontiers, Opportunities, and Challenges in Biochemical and Chemical Catalysis of CO2 Fixation. Chem. Rev. 2013, 3, 6621-6658).

[0003] Against this backdrop, many organometallic complexes have been studied for electrocatalytic CO2 reduction (Franke, R.; Schille, B.; Roemelt, M. Homogeneously Catalyzed Electroreduction of Carbon Dioxide-Methods, Mechanisms, and Catalysts. Chem. Rev. 2018, 118, 4631-4701), but most of them have several problems. For example, some of the transition metals that are generally studied are rare and expensive, some complexes are unstable during electrocatalytic reduction reactions, and the synthesis of desirable ligands is complex and not economical. Therefore, the inventors of this application have invented a soluble inorganic metal oxide cluster, i.e., a polyoxometalate, that can be used as an electrocatalyst for CO2 reduction. A polyoxometalate can be generally considered an anionic cluster formed from monomeric oxo species of transition metals having one or more bridging oxygen atoms. Interest in polyoxometalate chemistry is largely driven by their structure, size, redox activity, solubility, thermal stability, and charge density. Over the years, new classes of compounds with unique structures and electronic properties have been developed by modifying precursors of parent polyoxometalates. Original polyoxometalates substituted with transition metal ions are known as "transition metal-substituted polyoxometalates."

[0004] Polyoxometalates are attractive as catalysts because they are easy to synthesize, thermally and oxidatively stable, their inherent properties can be easily modified, and they can be used with excellent efficiency in conversions involving electron transfer (Neumann, R. Activation of Molecular Oxygen, Polyoxometalates and Liquid Phase Catalytic Oxidation. Inorg. Chem. 2010, 49, 3594 - 3601). Furthermore, many of these polyoxometalates exhibit reversible redox processes sensitive to the presence of protons. Also, polyoxometalates, although weak bases and nucleophiles, can promote the formation of hydrogen bond networks near the CO2 coordination center and promote proton-coupled electron transfer (Girardi, M.; Blanchard, S.; Griveau, S.; Simon, P.; Fontecave, M.; Bedioui, F.; Proust, A. Electro-Assisted Reduction of CO 2 to CO and Formaldehyde by (TOA)6[α-SiW11O39Co(_)] Polyoxometalate. Eur. J. Inorg. Chem. 2015, 3642 - 3648). Substituting lacunary polyoxometalates with transition metals usually increases the reactivity of the polyanion with weakly basic oxygen atoms on the surface. As a rational approach to such complexes, lacunary anions such as α- or β-[SiW9O 34 9- were prepared (G. Herve and A. Teze, Study of alpha-and beta-enneatungstosilicates and-germanates. Inorg. Chem., 1977, 16, 2115 - 2117), and trimetal-substituted polyoxometalates were prepared by encapsulating metal cations in the lacunary positions of the lacunary anions. In this way, polyoxometalate anions, [SiW9M3(L)3O 37 n- ​​(Figure 1) was prepared (Liu, J.; Ortega, F.; Sethuraman, P.; Katsoulis, DE; Costello, CE; Pope, MT Trimetallo Derivatives of Lacunary 9-Tungstosilicate. J. Chem. Soc., Dalton Trans. 1992, 1901-1906). In the formula, M = Co(II), Fe(III), Cu(II), Mn(II), Ni(II), Cr(III), Al(III), and Ga(III). Also, Fe(III) was included in the lacunarly position along with the other metals, thereby [PW9O 37 {Fe III 3- xNix(OAc)3}] (9+x)- , or [SiW9(Fe III )2M'(L)3O 37 ] n- There are also reports that it formed (where M' is Ni(II), Co(II), or Mn(II)) (Mizuno, N.; Nozaki, C.; Horose, T.; Tateishi, M.; Iwamoto, M. Liquid-phase oxygenation of hydrocarbons with molecular oxygen catalyzed by Fe, Ni-substituted Keggin-type heteropolyanion. J. Mol. Catal. A: Chem. 1997, 117, 159-168 and Girardi, M. Application des derives metalliques des polyoxometallates pour la catalyse d'electroreduction de CO2 Universite Pierre et Marie Curie, Paris VI 2016).

[0005] All known molecular and material electrocatalysts require fairly high overpotentials for the electrolytic reduction of CO2. Therefore, the main objective is to find catalysts with lower overpotentials and less electrical energy required to drive the catalytic reaction. The reduction of CO2 typically involves proton transfer, where one electron is transferred to CO2, forming the anionic radical CO2. ·- This overcomes the highly energy-absorbent transfer that forms a proton bond electron transfer reaction. Such proton bond electron transfer reactions are still slow, and efficient catalysts are needed to reduce the overpotential required to drive the reaction. Savant et al. used Mg as a Lewis acid. 2+The addition of thion improved the rate of reduction from CO2 to CO by Fetetraphenylporphyrin (FeTPP), thereby further improving the stability of the catalyst (Hammouche, M.; Lexa, D.; Momenteau, M.; Saveant, J.-M. Chemical catalysis of electrochemical reactions. Homogeneous catalysis of the electrochemical reduction of carbon dioxide by iron (″0″) porphyrins. Role of the addition of magnesium cations. J. Am. Chem. Soc. 1991, 113, 8455-8466). Lewis acids are thought to promote the cleavage of one CO bond of the bonded CO2 ligand, thereby producing CO. Another paper reports that Lewis acids can be used instead of Brønsted acids to increase the catalytic reaction rate of Mn bipyridine type catalysts (Sampson, MD; Kubiak, CP Manganese Electrocatalysts with Bulky Bipyridine Ligands: Utilizing Lewis Acids To Promote Carbon Dioxide Reduction at Low Overpotentials. J. Am. Chem. Soc. 2016, 138, 1386-1393). In fact, two catalytic regions were observed: a fast reaction with high turnover at high overpotential unaffected by Lewis acids, and a slow reaction with low turnover at low overpotential. [Overview of the project] [Means for solving the problem]

[0006] In one embodiment, the present disclosure provides a polyoxometalate compound represented by the following formula (I) or a solvate thereof. (Q) n [XM a M b M c (La )(L b )(L c )W9O 37 ] (I) During the ceremony, X is P, Si, As, Ge, Ga, B, or Al. M a M b , and M c These elements are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca. L a , L b , and L c These are independently selected from the group consisting of H2O, carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or none at all. Q is a cation such as a proton, alkali metal cation, alkaline earth metal cation, lanthanide cation, nitrogen-centered cation, phosphorus-centered cation, and any combination thereof. n is an integer between 4 and 13. M a M b , and M c At least one of them is Sn, Al, Zn, or Ga, or M a M b , and M c They are different from each other.

[0007] In further embodiments, the present disclosure provides a method for reducing carbon dioxide to carbon monoxide, formate or formic acid, formaldehyde, methanol, ethane, ethylene, ethanol, or any combination thereof. The process includes the step of reacting carbon dioxide with a polyoxometalate compound represented by the following formula (I) or its solvate, The present invention provides a method in which the reaction is carried out in an electrochemical cell comprising a cathode, an anode, optionally a reference electrode, optionally a membrane, and a polyoxometalate compound represented by the following formula (I) or its solvate as a carbon dioxide reduction catalyst. (Q) n [XM a M b M c (L a )(L b )(L c )W9O 37 ] (I) During the ceremony, X is P, Si, As, Ge, Ga, B, or Al. M a M b , and M c These elements are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca. L a , L b , and L c These are independently selected from the group consisting of H2O, carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or none at all. Q is a cation such as a proton, alkali metal cation, alkaline earth metal cation, lanthanide cation, nitrogen-centered cation, phosphorus-centered cation, and any combination thereof. n is an integer between 4 and 13. [Brief explanation of the drawing]

[0008] The subject matter considered to be the present invention is specifically pointed out and clearly asserted in the concluding section of the specification. However, the present invention, with respect to both its configuration and method of operation, as well as its purpose, features, and advantages, will be best understood by reading the following detailed description with reference to the accompanying drawings.

[0009] [Figure 1] Figure 1 shows a mixed polyhedron and ball-and-stick representation of the {SiMaMbMc(H2O)3W9O37}n-anion. W is the outer octahedron; Si is the central inner tetrahedron; MaMbMc is the three balls at the top; and O is the small light gray ball. Hydrogen atoms and countercations are not shown. [Figure 2A] Figures 2A and 2B show an example of an electrolytic cell. Figure 2A is a schematic design drawing of the electrolytic cell. [Figure 2B] Figure 2B is a photograph of an electrolytic cell.

[0010] For the sake of simplification and clarity, please understand that the elements shown are not necessarily drawn to a consistent scale. For example, the dimensions of some elements may be exaggerated compared to others for clarity. Furthermore, where appropriate, reference numbers are repeatedly used across drawings to indicate corresponding or similar elements. [Modes for carrying out the invention]

[0011] The following detailed description includes numerous specific details to provide a complete understanding of the invention. However, it will be understood by those skilled in the art that the invention may be carried out without using these specific details. In other examples, well-known methods, procedures, and components are not described in detail so as not to obscure the invention.

[0012] Polyoxometalate compounds of the present disclosure

[0013] In some embodiments, the disclosure provides a polyoxometalate compound represented by the following formula (I) or a solvate thereof. (Q) n [XM a M b M c (L a )(L b )(L c )W9O 37 ] (I) During the ceremony, X is P, Si, As, Ge, Ga, B, or Al. M a M b , and M cThese elements are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca. L a , L b , and L c These are independently selected from the group consisting of H2O, carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or none at all. Q is a cation such as a proton, alkali metal cation, alkaline earth metal cation, lanthanide cation, nitrogen-centered cation, phosphorus-centered cation, and any combination thereof. n is an integer between 4 and 13.

[0014] In some embodiments, the disclosure provides a polyoxometalate compound represented by the following formula (I) or a solvate thereof. (Q) n [XM a M b M c (L a )(L b )(L c )W9O 37 ] (I) During the ceremony, X is P, Si, As, Ge, Ga, B, or Al. M a M b , and M c These elements are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca. L a , L b , and L c These are independently selected from the group consisting of H2O, carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or none at all. Q is a cation such as a proton, an alkali metal cation, an alkaline earth metal cation, a lanthanide cation, a nitrogen-centered cation, a phosphorus-centered cation, and any combination thereof. n is an integer from 4 to 13. M a 、M b 、and M c At least one of them is Sn, Al, Zn, or Ga.

[0015] In some embodiments, the present disclosure provides a polyoxometalate compound represented by the following formula (I) or a solvate thereof. (Q) n [XM a M b M c (L a )(L b )(L c )W9O 37 (I) In the formula, X is P, Si, As, Ge, Ga, B, or Al. M a 、M b 、and M c are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca. L a 、L b 、and L c are independently selected from the group consisting of H2O, carboxylate, oxyanion, halide or pseudohalide, carbonate, and bicarbonate, or do not exist. Q is a cation such as a proton, an alkali metal cation, an alkaline earth metal cation, a lanthanide cation, a nitrogen-centered cation, a phosphorus-centered cation, and any combination thereof. n is an integer from 4 to 13. M a 、M b 、and M c At least two of them are different from each other.

[0016] In some embodiments, the disclosure provides a polyoxometalate compound represented by the following formula (I) or a solvate thereof. (Q) n [XM a M b M c (L a )(L b )(L c )W9O 37 ] (I) During the ceremony, X is P, Si, As, Ge, Ga, B, or Al. M a M b , and M c These elements are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca. L a , L b , and L c These are independently selected from the group consisting of H2O, carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or none at all. Q is a cation such as a proton, alkali metal cation, alkaline earth metal cation, lanthanide cation, nitrogen-centered cation, phosphorus-centered cation, and any combination thereof. n is an integer between 4 and 13. M a M b , and M c They are different from each other (i.e., M a M b , and M c (These are three metals selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca).

[0017] In another embodiment, non-limiting examples of oxyanions include borates, carbonates, nitrates, phosphates, sulfates, chlorates, perchlorates, iodates, periodates, tosylates, mesylates, and triflates.

[0018] In another embodiment, the anion of the polyoxometalate is [PW9O 37 {Fe III 3-x Ni x (L)3}] q- (x=1~2), [SiW9(Fe III )2Ni II (L)3O 37 ] n- [SiW9(Fe III )2Mn II (L)3O 37 ] n- , or [SiW9(Fe III )2Co II (L)3O 37 ] n- ,isn't it.

[0019] In some embodiments, equation (I):(Q) n [XM a M b M c (L a )(L b )(L c )W9O 37 In the given expression, Q is a cation selected from the group consisting of protons, alkali metal cations, alkaline earth metal cations, lanthanide cations, nitrogen-centered cations, phosphorus-centered cations, and any combination thereof. In other embodiments, Q is a proton. In other embodiments, Q is an alkali metal cation. In other embodiments, Q is an alkaline earth metal cation. In other embodiments, Q is a lanthanide cation. In other embodiments, Q is a nitrogen-centered cation. In other embodiments, Q is a phosphorus-centered cation. In other embodiments, Q is R1R2R3R4N + In the formula, R1 is H, alkyl, aryl, or alkylaryl, and R2 is H, alkyl, aryl, alkylaryl, Cy H 2y+1 (y≧8), or C z H 2z+1 COOH (z≧7), and R3 and R4 are independently H, alkyl, aryl, alkylaryl, or (CH2CH2O) m The molecule is CH2CH2R5 (m≧3), where R5 is H, OH, alkyl, halide, or pseudohalide.

[0020] In some embodiments, Q is R1R2R3R4N + And in the formula, R2 is C y H 2y+1 In this embodiment, y ≥ 8. In other embodiments, y is an integer between 8 and 50. In other embodiments, y is an integer between 8 and 40. In other embodiments, y is an integer between 8 and 30. In other embodiments, y is an integer between 8 and 20.

[0021] In some embodiments, Q is R1R2R3R4N + And in the formula, R2 is C z H 2z+1 In other embodiments, z is an integer between 7 and 50. In other embodiments, z is an integer between 7 and 40. In other embodiments, z is an integer between 7 and 30. In other embodiments, z is an integer between 7 and 20.

[0022] In some embodiments, Q is R1R2R3R4N + Therefore, R3 and R4 are either identical or different from each other. In some embodiments, R3 and R4 are (CH2CH2O) independently of each other. m In other embodiments, m is an integer between 3 and 50. In other embodiments, m is an integer between 3 and 40. In other embodiments, m is an integer between 3 and 30. In other embodiments, m is an integer between 3 and 20. In other embodiments, m is an integer between 3 and 15. In other embodiments, m is an integer between 3 and 10.

[0023] In some embodiments, Q is R1R2R3R4N + In the formula, R1 is ethyl and R2 is C z H 2z+1 It is COOH, z≧7, and R3 and R4 are (CH2CH2O) m H is and m = 6 to 20. In other embodiments, Q is R1R2R3R4N + In the formula, R1 is methyl, R2 is tetradecyl, hexadecyl, or octadecyl, and R3 and R4 are (CH2CH2O) m H is such that m = 5 to 10.

[0024] In some embodiments, equation (I):(Q) n [XM a M b M c (L a )(L b )(L c )W9O 37 In the polyoxometalate compounds, Q is a nitrogen-centered cation, and non-limiting examples of nitrogen-centered cations include quaternary ammonium, pyridinium, and imidazolium cations.

[0025] In one embodiment, the quaternary ammonium is selected from the group consisting of tetrahexylammonium, tetrabutylammonium, trioctylmethylammonium, cetyltrimethylammonium, tetraoctylammonium, tetraethylammonium, tetramethylammonium, and benzyltrimethylammonium, each representing a separate embodiment of the present disclosure.

[0026] In some embodiments, an example of a phosphorus-centered cation is a phosphonium cation, such as tetraphenylphosphonium.

[0027] When used herein, the term "alkyl," used alone or as part of another group, means, in one embodiment, "C1-C 12The term "alkyl" refers to linear or branched, saturated or unsaturated (e.g., alkenyl, alkynyl) groups, the latter of which are only those with two or more carbon atoms in the alkyl chain and may include mixed structures. Non-limiting examples include alkyl groups with 1 to 6 carbon atoms (C1-C6 alkyl) or alkyl groups with 1 to 4 carbon atoms (C1-C4 alkyl). Examples of saturated alkyl groups, but not limited to these, include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, amyl, tert-amyl, and hexyl. Examples of alkenyl groups, but not limited to these, include vinyl, allyl, and butenyl. Examples of alkynyl groups, but not limited to these, include ethynyl and propynyl. Similarly, "C1-C 12 The term "alkylene" refers to a divalent radical with 1 to 12 carbon atoms.

[0028] The alkyl group may be unsubstituted or substituted with one or more substituents selected from the group consisting of halogen, hydroxy, alkoxy, aryloxy, alkylaryloxy, heteroaryloxy, oxo, cycloalkyl, phenyl, heteroaryl, heterocyclyl, naphthyl, amino, alkylamino, arylamino, heteroarylamino, dialkylamino, diarylamino, alkylarylamino, alkylheteroarylamino, arylheteroarylamino, acyl, acyloxy, nitro, carboxy, carbamoyl, carboxamide, cyano, sulfonyl, sulfonylamino, sulfinyl, sulfinylamino, thiol, alkylthio, arylthio, and alkylsulfonyl groups. Any substituent may be unsubstituted or further substituted with any of the substituents listed above.

[0029] As used herein, the term “alkylaryl,” used alone or as part of another group, refers to the alkyl group defined above, which in some embodiments is substituted with the aryl group as defined herein.

[0030] As used herein, the term “aryl,” used alone or as part of another group, refers to an aromatic ring system having 6 to 14 ring carbon atoms. Aryl rings can be monocyclic, bicyclic, tricyclic, etc. Non-limiting examples of aryl groups include phenyl and naphthyl (e.g., 1-naphthyl, 2-naphthyl). Aryl groups may be unsubstituted or substituted via available carbon atoms with one or more substituents selected from the group consisting of halogen, hydroxy, alkoxy, aryloxy, alkylaryloxy, heteroaryloxy, oxo, cycloalkyl, phenyl, heteroaryl, heterocyclyl, naphthyl, amino, alkylamino, arylamino, heteroarylamino, dialkylamino, diarylamino, alkylarylamino, alkylheteroarylamino, arylheteroarylamino, acyl, acyloxy, nitro, carboxy, carbamoyl, carboxamide, cyano, sulfonyl, sulfonylamino, sulfinyl, sulfinylamino, thiol, alkylthio, arylthio, and alkylsulfonyl groups. Any substituent may be unsubstituted or may be further substituted with any of the substituents described above.

[0031] In some embodiments, n is an integer between 4 and 13. In other embodiments, n is an integer between 4 and 6, 4 and 9, 6 and 3, or 5 and 10, or any range between 4, 5, 6, 7, 8, 9, 10, 11, 12, and 13.

[0032] In some embodiments, the M of the compound of formula (I) or formula (Ia) a M b , and M c , or M'' are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca. In some embodiments, M a M b , and M c They are different from each other. In some embodiments, M a M b, and M c At least two of them are different from each other. In some embodiments, M a M b , and M c At least one of them is Cr. In some embodiments, M a M b , and M c At least one of them is Mn. In some embodiments, M a M b , and M c At least one of them is Fe. In some embodiments, M a M b , and M c At least one of them is Co. In some embodiments, M a M b , and M c At least one of them is Ni. In some embodiments, M a M b , and M c At least one of them is Cu. In some embodiments, M a M b , and M c At least one of them is Zn. In some embodiments, M a M b , and M c At least one of them is Al. In some embodiments, M a M b , and M c At least one of them is Ga. In some embodiments, M a M b , and M c At least one of them is Sn. In some embodiments, M a M b , and M c At least one of them is Sb. In some embodiments, M a M b , and M c At least one of them is In. In some embodiments, M a M b , and Mc At least one of them is Sc. In some embodiments, M a M b , and M c At least one of them is Sr. In some embodiments, M a M b , and M c At least one of them is Mg. In some embodiments, M a M b , and M c At least one of them is Y. In some embodiments, M a M b , and M c At least one of them is Yb. In some embodiments, M a M b , and M c At least one of them is Ba. In some embodiments, M a M b , and M c At least one of them is Ca. In some embodiments, M a M b , and M c At least one of these is Sn, Al, Zn, or Ga.

[0033] In some embodiments, the polyoxometalate of formula (I) is (Q) n [XCu2M´´L a L b LcW9O 37 ], where M'' is selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca. In one embodiment, M'' is Fe, Ni, Al, Ga, Sn, or Zn. Each represents a distinct embodiment of the present disclosure.

[0034] In some embodiments, the polyoxometalate of formula (I) is (Q) n [XCuFeZnL a L b LcW9O 37 ], (Q) n[XCu2FeL a L b LcW9O 37 ]、(Q) n [XCuFe2L a L b LcW9O 37 ]、(Q) n [XCu2NiL a L b LcW9O 37 ]、(Q) n [XCuNi2L a L b LcW9O 37 ]、(Q) n [XCu2ZnL a L b LcW9O 37 ]、(Q) n [XCu2GaL a L b LcW9O 37 ]、(Q) n [XCu2AlL a L b LcW9O 37 ]、(Q) n [XCu2SnL a L b LcW9O 37 ]、(Q) n [XCu2SbL a L b LcW9O 37 ]、(Q) n [XCu2InL a L b LcW9O 37 ]、(Q) n [XCuFeNiL a L b LcW9O 37 ]、(Q) n [XCuFeAlL a L b LcW9O 37 ]、(Q) n [XCuFeGaL a L b LcW9O 37 ]、(Q) n [XCuFeSnL a L b LcW9O 37 ]、(Q) n[XCuNiZnL a L b LcW9O 37 ], (Q) n [XCuNiAlL a L b LcW9O 37 ], (Q) n [XCuCoZnL a L b LcW9O 37 ], (Q) n [XCuCoAlL a L b LcW9O 37 ], (Q) n [XCuMnZnL a L b LcW9O 37 ], or (Q) n [XCuMnAlL a L b LcW9O 37 ]

[0035] In some embodiments, X in the polyoxometalate of formula (I) is Si or P.

[0036] In some embodiments, the polyoxometalate of formula (I) or (Ia) is L a , L b , and L c These are independently selected from the group consisting of H2O, carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or none at all. In other embodiments, L of the polyoxometalate of formula (I) a , L b , and L c These are H2O, independently of each other. In other embodiments, L of the polyoxometalate of formula (I) a , L b , and L c These are, independently of each other, carboxylates. In other embodiments, L of the polyoxometalate of formula (I) a , L b , and L c These are oxyanions, independently of each other. In other embodiments, L of the polyoxometalate of formula (I)a , L b , and L c These are, independently of each other, halides. In other embodiments, L of the polyoxometalate of formula (I) a , L b , and L c These are, independently of each other, pseudohalides. In other embodiments, L of the polyoxometalate of formula (I) a , L b , and L c These are, independently of each other, carbonates. In other embodiments, L of the polyoxometalate of formula (I) a , L b , and L c These are, independently of each other, bicarbonates. In other embodiments, L of the polyoxometalate of formula (I) a , L b , and L c It does not exist.

[0037] In some embodiments, the polyoxometalate of formula (I) is (Q)9[SiCu2Fe(H2O)3W9O 37 ], (Q)8[SiCuFe2(H2O)3W9O 37 ], (Q) 10 [SiCu2Ni(H2O)3W9O 37 ], (Q) 10 [SiCuNi2(H2O)3W9O 37 ], (Q)9[SiCuFeNi(H2O)3W9O 37 ], (Q)8[SiFe2Al(H2O)3W9O 37 ], (Q)9[SiFeGa2(H2O)3W9O 37 ], (Q) 10 [SiCu2Zn(H2O)3W9O 37 ], (Q)9[SiCu2Al(H2O)3W9O 37 ], (Q)9[SiCu2Ga(H2O)3W9O 37 ], (Q)8[SiCu2Sn(H2O)3W9O 37 ], (Q)9[SiCuFeZn(H2O)3W9O 37 ], (Q)8[SiCuFeAl(H2O)3W9O 37], (Q)8[SiCuFeGa(H2O)3W9O 37 ], (Q)7[SiCuFeSn(H2O)3W9O 37 ], (Q) 10 [SiCuNiZn(H2O)3W9O 37 ], or (Q)9[SiCuNiAl(H2O)3W9O 37 Each represents a distinct embodiment of the present disclosure.

[0038] How to use

[0039] In further embodiments, this disclosure may extend to: A method for reducing carbon dioxide to carbon monoxide, formate or formic acid, formaldehyde, methanol, ethane, ethylene, ethanol, or any combination thereof, The process includes the step of reacting carbon dioxide with a polyoxometalate compound represented by the following formula (I) or its solvate, The present invention provides a method in which the reaction is carried out in an electrochemical cell comprising a cathode, an anode, optionally a reference electrode, optionally a membrane, and a polyoxometalate compound represented by the following formula (I) or its solvate as a carbon dioxide reduction catalyst. (Q) n [XM a M b M c (L a )(L b )(L c )W9O 37 ] (I) During the ceremony, X is P, Si, As, Ge, Ga, B, or Al. M a M b , and M c These elements are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca. L a , L b , and L cThese are independently selected from the group consisting of H2O, carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or none at all. Q is a cation such as a proton, alkali metal cation, alkaline earth metal cation, lanthanide cation, nitrogen-centered cation, phosphorus-centered cation, and any combination thereof. n is an integer between 4 and 13.

[0040] In some embodiments, the carbon dioxide reduction method of the present disclosure includes the step of reacting carbon dioxide with a polyoxometalate compound represented by formula (I) or a solvate thereof, M a M b , and M c These are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca, M a M b , and M c At least one of these is Sn, Al, Zn, or Ga. In other embodiments, M a M b , and M c These are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca, M a M b , and M c At least two of them are different from each other. In other embodiments, M a M b , and M c These are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca, M a M b , and M c They are different from each other.

[0041] In some embodiments, the carbon dioxide reduction method of the present disclosure aims to reduce carbon dioxide to carbon monoxide. In some embodiments, the carbon dioxide reduction method of the present disclosure aims to reduce carbon dioxide to formate or formic acid. In some embodiments, the carbon dioxide reduction method of the present disclosure aims to reduce carbon dioxide to formaldehyde. In some embodiments, the carbon dioxide reduction method of the present disclosure aims to reduce carbon dioxide to methanol. In some embodiments, the carbon dioxide reduction method of the present disclosure aims to reduce carbon dioxide to ethane, ethylene, ethanol, or any combination thereof.

[0042] In some embodiments, the electrochemical cell used in this disclosure includes a working electrode (cathode), a counter electrode (anode), and optionally a reference electrode. In one embodiment, the electrochemical cell used in this disclosure includes a working electrode, a counter electrode, and a reference electrode. In one embodiment, electrodes of any material and shape known in the art can be used in this disclosure.

[0043] In one embodiment, the electrochemistry is a gas diffusion electrolytic cell.

[0044] In some embodiments, the electrolyte of the electrochemical cell is any electrolyte known in the art.

[0045] In some embodiments, the electrolyte is QZ, where Z is an oxyanion, halide, pseudohalide, or PF6. - , or BF4 - And Q is as defined in equation (I).

[0046] In some embodiments, a solvent is present in the electrochemical cell, and the solvent is any solvent known in the art.

[0047] In some embodiments, the solvent is water with a basic, neutral, or acidic pH.

[0048] In some embodiments, the solvent is an organic solvent or a combination of several organic solvents. Non-limiting examples of organic solvents include acetonitrile, glutaronitrile, adiponitrile, dimethylformamide, dimethylacetamide, dimethyl sulfone, dimethyl sulfoxide, tetrahydrofuran, glycyle, diglycyle, ethylene glycol oligomer, ethylene glycol polymer, monoalkylated ethylene glycol oligomer, monoalkylated ethylene glycol polymer, dialkylated ethylene glycol oligomer, dialkylated ethylene glycol polymer, or any combination thereof.

[0049] In some embodiments, the cathode of the electrochemical cell is carbon, such as a carbon disk, carbon rod, carbon cloth, or carbon paper.

[0050] In some embodiments, the cathode of the electrochemical cell is a metal such as titanium, iron, or copper.

[0051] In some embodiments, the anode of the electrochemical cell is a Pt wire, carbon, iridium oxide, ruthenium oxide, iron, nickel, a combination of iron and nickel, or a cobalt-containing compound.

[0052] In some embodiments, the membrane of the electrochemical cell is any membrane known in the art.

[0053] In some embodiments, the film is anionic; in some embodiments, the film is Nafion; in some embodiments, the film is a laminar material such as zirconia or alumina; and in some embodiments, the film is a porous organic polymer.

[0054] In some embodiments, the applied potential of the electrochemical cell is Fc / Fc + For this, the range is between -3.5~0.0V, -3.0~0.0V, -2.5~0.0V, -2.0~0.0V, or -1.5~0.0V. In certain embodiments, the applied potential is Fc / Fc +The voltage is between -2.5V and -1.5V.

[0055] In another embodiment, a glassy carbon disk (d=3mm) is used as the working electrode, a 15mm Pt wire separated by glass frit is used as the counter electrode, and Fc / Fc is used as the reference electrode. + This configuration is used. In another embodiment, a titanium metal is used as the working electrode, a carbon cloth as the counter electrode, and a Nafion film as the film. Each of these represents a separate embodiment of the present disclosure.

[0056] In one embodiment, the electrochemical cell comprises a cathode, an anode, a polyoxometalate compound (a compound of formula (I)), and an electrolyte.

[0057] In one embodiment, the electrochemical cell includes a cathode, an anode, a polyoxometalate compound, a reference electrode, and an electrolyte.

[0058] In one embodiment, the electrocatalytic reaction is carried out in an undivided cell in an organic solvent.

[0059] In one embodiment, the electrocatalytic reaction is carried out in a divided cell structure having a polymer membrane electrolyte that separates the anode and cathode compartments.

[0060] In one embodiment, the electrocatalytic reaction is carried out in an organic solvent, i.e., in an electrolyte with a split-cell structure having a polymer membrane electrolyte that separates the anode and cathode compartments.

[0061] In one embodiment, the electrode catalytic reaction is carried out in a flow cell membrane electrolytic cell in which the polyoxometalate is dissolved in a solvent.

[0062] In one embodiment, the electrode catalyst reaction is carried out in a gas diffusion electrolytic cell.

[0063] In one embodiment, the electrochemical cell of the Disclosure comprises a cathode, an anode, and a polyoxometalate compound (represented by formula (I)). In one embodiment, the polyoxometalate compound of the Disclosure is used in solid form. In one embodiment, the polyoxometalate compound of the Disclosure is dissolved in a solution. In one embodiment, the solution comprises a solvent and a solute, the solute being the polyoxometalate compound of the Disclosure and optionally an electrolyte. In one embodiment, the solvent is acetonitrile. In one embodiment, the concentration of the polyoxometalate compound of the Disclosure is in the range of 0.1–5 mM, 0.1–1 mM, 0.1–2 mM, or 1–5 mM. In another embodiment, the concentration of the polyoxometalate compound of the Disclosure is 2 mM. In one embodiment, the electrolyte concentration in the solution is between 0.01–1 M or 0.05–1 M. In another embodiment, the electrolyte concentration is 0.1 M. Each represents a distinct embodiment of the Disclosure.

[0064] In one embodiment, the electrolyte further comprises additives, stabilizers, salts, ions, or any combination thereof. In one embodiment, the pH of the electrolyte is adjusted. In one embodiment, the pH of the solution containing water and the compound is in the range of 0 to 14. In one embodiment, the pH value of the solution is acidic. In one embodiment, the pH of the solution is basic. In one embodiment, the pH of the solution is in the range of 6 to 8, 5 to 9, 4 to 10, 3 to 11, 2 to 12, or 1 to 13. Each represents a distinct embodiment of the present disclosure.

[0065] In one embodiment, the method of the Disclosure comprises the step of contacting the polyoxometalate compound of the Disclosure with carbon dioxide in an electrochemical cell for 0.1 to 72 hours. In another embodiment, the contact time is 0.1 to 2 hours. In another embodiment, the contact time is 2 to 5 hours. In another embodiment, the contact time is 5 to 10 hours. In another embodiment, the contact time is 10 to 15 hours. In another embodiment, the contact time is 10 to 20 hours. In another embodiment, the contact time is 15 to 30 hours. In another embodiment, the contact time is 20 to 50 hours. In another embodiment, the contact time is 25 to 72 hours. In another embodiment, the contact time is 1 hour. In another embodiment, the contact time is 15 hours. Each represents a distinct embodiment of the Disclosure.

[0066] Preparation of Compounds in this Disclosure

[0067] In one embodiment, the anion of the polyoxometalate of formula (I) of the present disclosure is prepared by the following method: In one embodiment, a water-soluble α- or β-[XW9O 34 ] 9- Anions and each salt is M w L y By reacting a mixture of up to three salts represented by zH2O or the compound represented by Ia below (see further embodiments below) in water, an anion [XM a M b M c (L a L b L c )W9O 37 ] n- Prepare the anion (of formula (I)). M a M b M c (L a ) na (L b ) nb (L c ) nc Ia During the ceremony, X, M a Mb M c , L a , L b , L c , and n are as described above in this specification. w and y are independent integers between 1 and 5. z is an integer between 0 and 10. na, nb, and nc are independent integers between 1 and 5. M is Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sc, Sr, Mg, Y, Ba, or Ca. L is selected from the group consisting of carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or is absent.

[0068] In one embodiment, the present disclosure is [XM a M b M c (L a L b L c )W9O 37 ] n- A method for preparing, Water-soluble α- or β-[XW9O 34 ] 9- Anions and each salt is M w L y The step involves reacting a mixture of up to three salts represented by zH2O or a compound represented by Ia below in water, thereby [XM a M b M c (L a L b L c )W9O 37 ] n- A method for preparing [the substance] is provided. M a M b M c (L a ) na (L b ) nb (L c ) nc Ia During the ceremony, X, Ma M b M c , L a , L b , L c , and n are as described above in this specification. w and y are independent integers between 1 and 5. z is an integer between 0 and 10. na, nb, and nc are independent integers between 1 and 5. M is Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sc, Sr, Mg, Y, Ba, or Ca. L is selected from the group consisting of carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or is absent.

[0069] Q' n [XM a M b M c (L a L b L c )W9O 37 The specific preparation method for [ ] is as follows:

[0070] In one embodiment, Q' n [SiM a M b M c (L a L b L c )W9O 37 ] is Na9[β-SiW9O 37 ] in water, each salt is M w L y It is produced by reacting it with a mixture of up to three types of salts represented by zH2O. During the ceremony, w, y, z, M a M b M c , L a , L b , L c , and n are as described above in this specification. Q' is a cation, such as a proton, an alkali metal cation, or a combination thereof. L is selected from the group consisting of carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or is absent.

[0071] In one embodiment, Na9[α-SiW9O 37 ] in water, each salt is M w L y • Reacts with a mixture of up to three salts represented by zH2O, Q' n [SiM a M b M c (L a L b L c )W9O 37 Generates ]. During the ceremony, w, y, z, M a M b M c , L a , L b , L c , and n are as described above in this specification. Q' is a cation, such as a proton, an alkali metal cation, or a combination thereof. L is selected from the group consisting of carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or is absent.

[0072] In one embodiment, Na9[PW9O 34 ] in water, each salt is M w L y • Reacts with a mixture of up to three salts represented by zH2O, Q' n [PM a M b M c (L a L b L c )W9O 37 Generates ]. During the ceremony, w, y, z, M a M b Mc , L a , L b , L c , and n are as described above in this specification. Q' is a cation, such as a proton, an alkali metal cation, or a combination thereof. L is selected from the group consisting of carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or is absent.

[0073] In one embodiment, Na9[β-SiW9O 34 Compound M in water a M b M c (L a ) na (L b ) nb (L c ) nc This elicits a response, Q' n [SiM a M b M c (L a L b L c )W9O 37 ] generates (where y, Q', M a M b M c , L a , L b , L c (wherein n is as described above in this specification). In another embodiment, na + nb + nc = 9.

[0074] In one embodiment, Na9[α-SiW9O 34 Compound M in water a M b M c (L a ) na (L b ) nb (L c ) nc This elicits a response, Q' n [SiM a M b M c (L a Lb L c )W9O 37 ] generates (where y, Q', M a M b M c , L a , L b , L c (wherein n is as described above in this specification). In another embodiment, na + nb + nc = 9.

[0075] In one embodiment, Na9[PW9O 34 Compound M in water a M b M c (L a ) na (L b ) nb (L c ) nc This elicits a response, Q' n [PM a M b M c (L a L b L c )W9O 37 ] generates (where w, y, Q', M a M b M c , L a , L b , L c (wherein n is as described above in this specification). In another embodiment, na + nb + nc = 9.

[0076] [XM a M b M c (L a L b L c )W9O 37 ] n- The specific preparation method is as follows:

[0077] In one embodiment, [XM a M b M c (L a L b L c )W9O 37] n- This is water-soluble α- or β-[XW9O 34 ] 9- Anions and each salt is M w L y It is produced by reacting a mixture of up to three types of salts, represented as zH2O, in water. During the ceremony, w, y, z, X, M, M a M b M c , L a , L b , L c , and n are as described above in this specification. L is selected from the group consisting of carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or is absent.

[0078] In one embodiment, [XM a M b M c (L a L b L c )W9O 37 ] n- This is water-soluble α- or β-[XW9O 34 ] 9- Anions and compound M a M b M c (L a ) na (L b ) nb (L c ) nc It is produced by reacting with in water (wherein y, X, M, M a M b M c , L a , L b , L c (wherein n is as described above in this specification). In another embodiment, na + nb + nc = 9.

[0079] [XM a M b M c (L a L b Lc )W9O 37 ] n- The specific method for cation exchange from Q' to Q is as follows:

[0080] In one embodiment, (Q) n [XM a M b M c (L a L b L c )W9O 37 ](Q is selected from the group consisting of alkaline earth metal salts, lanthanide salts, quaternary ammonium salts, quaternary phosphonium salts, and any combination thereof) is (Q') n [XM a M b M c (L a L b L c )W9O 37 ] is prepared by reacting it with an alkaline earth metal salt, a lanthanide salt, a quaternary ammonium salt, a quaternary phosphonium salt, or any combination thereof (wherein Q', X, M in the formula). a M b M c , L a , L b , L c , and n are as described above in this specification.

[0081] In one embodiment, (Q) n [SiM a M b M c (L a L b L c )W9O 37 ](Q is selected from the group consisting of alkaline earth metal salts, lanthanide salts, quaternary ammonium salts, quaternary phosphonium salts, and any combination thereof) is (Q') n [SiM a M b M c (L a L b L c )W9O 37] is prepared by reacting it with an alkaline earth metal salt, a lanthanide salt, a quaternary ammonium salt, a quaternary phosphonium salt, or any combination thereof (wherein Q', X, M in the formula). a M b M c , L a , L b , L c , and n are as described above in this specification.

[0082] In one embodiment, (Q) n [PM a M b M c (L a L b L c )W9O 37 ](Q is selected from the group consisting of alkaline earth metal salts, lanthanide salts, quaternary ammonium salts, quaternary phosphonium salts, and any combination thereof) is (Q') n [PM a M b M c (L a L b L c )W9O 37 ] is prepared by reacting it with an alkaline earth metal salt, a lanthanide salt, a quaternary ammonium salt, a quaternary phosphonium salt, or any combination thereof (wherein Q', X, M in the formula). a M b M c , L a , L b , L c , and n are as described above in this specification.

[0083] M a M b M c (L a ) na (L b ) nb (L c ) nc compound

[0084] In one embodiment, the present disclosure provides a mixed metal salt compound represented by the anion of formula (Ia) below. M a M b M c (L a ) na (L b ) nb (L c ) nc (Ia) During the ceremony, M a M b , and M c These elements are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca. L a , L b , and L c These are independently selected from the group consisting of H2O, carboxylates, oxyanions, halides or pseudohalides, carbonates, and bicarbonates, or none at all. na, nb, and nc are independent integers between 1 and 5. Q is a cation such as a proton, alkali metal cation, alkaline earth metal cation, lanthanide cation, nitrogen-centered cation, phosphorus-centered cation, and any combination thereof. n is an integer between 4 and 13.

[0085] In other embodiments, M a M b , and M c These are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca, M a M b , and M c At least one of these is Sn, Al, Zn, or Ga. In other embodiments, M a M b , and M cThese are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca, M a M b , and M c At least two of them are different from each other. In other embodiments, M a M b , and M c These are independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca, M a M b , and M c They are different from each other (i.e., M a M b , and M c (These are three metals selected from the above group.)

[0086] In another embodiment, the sum of na, nb, and nc (i.e., na + nb + nc) is in the range of 3 to 15, 3 to 5, 3 to 10, 10 to 15, 12 to 15, 5 to 15, 7 to 12, or 8 to 11. In yet another embodiment, na + nb + nc = 9.

[0087] In one embodiment, formula (Ia) is CuFeZn(L a ) na (L b ) nb (L c ) nc Cu2Fe(L a ) na (L b ) nb (L c ) nc CuFe2(L a ) na (L b ) nb (L c ) nc Cu2Ni(L a ) na (L b ) nb (L c ) nc CuNi2(La ) na (L b ) nb (L c ) nc Cu2Zn(L a ) na (L b ) nb (L c ) nc Cu2Ga(L a ) na (L b ) nb (L c ) nc Cu2Al(L a ) na (L b ) nb (L c ) nc Cu2Sc(L a ) na (L b ) nb (L c ) nc Cu2Mg(L a ) na (L b ) nb (L c ) nc Fe2Ni(L a ) na (L b ) nb (L c ) nc FeNi2(L a ) na (L b ) nb (L c ) nc CuFeNi(L a ) na (L b ) nb (L c ) nc CuFeAl(L a ) na (L b ) nb (L c ) nc CuNiZn(L a ) na (L b ) nb (L c) nc , CuNiAl(L a ) na (L b ) nb (L c ) nc , CuCoZn(L a ) na (L b ) nb (L c ) nc , CuCoAl(L a ) na (L b ) nb (L c ) nc , CuMnZn(L a ) na (L b ) nb (L c ) nc , or CuMnAl(L a ) na (L b ) nb (L c ) nc is represented by.

[0088] In one embodiment, formula (Ia) is [Cu2Fe(MeCOO)6(H2O)3], [Cu2Ni(MeCOO)6(H2O)3], [Cu2Zn(MeCOO)6(H2O)3], [Cu2Ga(MeCOO)6(H2O)3], [Cu2Al(MeCOO)6(H2O)3], [Cu2Sc(MeCOO)6(H2O)3], [Cu2Mg(MeCOO)6(H2O)3], [CuFeNi(MeCOO)6(H2O)3], [CuFeZn(MeCOO)6(H2O)3], [CuFeAl(MeCOO)6(H2O)3], [CuNiZn(MeCOO)6(H2O)3], or [CuNiAl(MeCOO)6(H2O)3]. Each represents a separate embodiment of the present disclosure.

[0089] In one embodiment, the compound represented by the following formula (Ia) has each salt as M w L yIt is prepared by reacting up to three salts represented by ·zH2O and isolating the salt thus obtained as a compound represented by formula (Ia). M a M b M c (L a ) na (L b ) nb (L c ) nc (Ia) In the formula, and y are, independently of each other, integers from 1 to 5. z is an integer from 0 to 10. L a 、L b 、and L c are each independently selected from the group consisting of carboxylate, oxyanion, halide or pseudohalide, carbonate, and bicarbonate, or do not exist. M a 、M b 、and M c are each independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca.

[0090] In one embodiment, the present disclosure is a method for preparing a compound represented by the following formula (Ia), each salt is M w L y mixing solutions of up to three salts represented by ·zH2O; isolating the salt thus obtained as a compound represented by formula (Ia); and providing a method comprising the steps. M a M b M c (L a ) na (L b ) nb (L c ) nc (Ia) w, y, z, L in the formula a 、L b 、Lc , and also, M a M b , and M c This is as described above in this specification.

[0091] In another embodiment, the solution is an aqueous solution or another solution known in the art. In another embodiment, the salt solution is filtered before mixing. In another embodiment, the isolation of the compound represented by the following formula (Ia) involves any isolation steps known in the art (non-limiting examples include evaporation, precipitation / crystallization, extraction, sublimation, etc.). In another embodiment, isolation is M w L y This includes vacuum evaporation of a mixture obtained by mixing salts represented by zH2O with each other, each representing a distinct embodiment of the present disclosure. M a M b M c (L a ) na (L b ) nb (L c ) nc (Ia)

[0092] Specific Embodiments

[0093] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [XCu2M´´L a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide. M'' is selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca.

[0094] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [SiCu2M´´L a L b L c W9O 37A method for reducing carbon dioxide to carbon monoxide is provided by reacting it or its solvate with carbon dioxide.

[0095] In one embodiment, the present disclosure provides a method for reducing carbon dioxide to carbon monoxide by reacting a polyoxometalate compound (Q) n [PCu2M´´L a L b L c W9O 37 or its solvate with carbon dioxide.

[0096] In one embodiment, the present disclosure provides a method for reducing carbon dioxide to carbon monoxide by reacting a polyoxometalate compound (Q) n [XCuFeZnL a L b L c W9O 37 or its solvate with carbon dioxide.

[0097] In one embodiment, the present disclosure provides a method for reducing carbon dioxide to carbon monoxide by reacting a polyoxometalate compound (Q) n [SiCuFeZnL a L b L c W9O 37 or its solvate with carbon dioxide.

[0098] In one embodiment, the present disclosure provides a method for reducing carbon dioxide to carbon monoxide by reacting a polyoxometalate compound (Q) n [PCuFeZnL a L b L c W9O 37 or its solvate with carbon dioxide.

[0099] In one embodiment, the present disclosure provides a method for reducing carbon dioxide to carbon monoxide by reacting a polyoxometalate compound (Q) n [XCuFeAlL aL b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0100] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [SiCuFeAlL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0101] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [PCuFeAllL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0102] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [XCuFeGaL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0103] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [SiCuFeGaL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0104] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [PCuFeGaL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0105] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [XCuFeSnL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0106] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [SiCuFeSnL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0107] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [PCuFeSnL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0108] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [XCuNiZnL a L b L c W9O 37The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0109] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [SiCuNiZnL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0110] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [PCuNiZnL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0111] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [XCuNiAlL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0112] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [SiCuNiAlL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0113] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [PCuNiAlL aL b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0114] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [XCuNiGaL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0115] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [SiCuNiGaL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0116] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [PCuNiGaL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0117] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [XCuCoZnL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0118] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [SiCuCoZnL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0119] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [PCuCoZnL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0120] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [XCuCoAlL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0121] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [SiCuCoAlL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0122] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [PCuCoAlL a L b L c W9O 37The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0123] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [XCuMnZnL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0124] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [SiCuMnZnL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0125] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [PCuMnZnL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0126] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [XCuMnAlL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0127] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [SiCuMnAlL aL b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0128] In one embodiment, the present disclosure relates to a polyoxometalate compound (Q) in an electrochemical cell. n [PCuMnAlL a L b L c W9O 37 The present invention provides a method for reducing carbon dioxide to carbon monoxide by reacting ] or its solvate with carbon dioxide.

[0129] In some embodiments, within the specific embodiments described above, for the compound of formula (I), X, Q, L a , L b , L c , and n are as described above in this specification.

[0130] Examples

[0131] Example 1: {SiW9O} as a cesium salt 37 [Cu2Ga(L)]3} 9- Synthesis of (L=H2O or OAc - ):

[0132] A 70 mL aqueous solution of sodium acetate trihydrate (0.32 mol) was added to a 70 mL filtered and stirred solution of copper(II) nitrate trihydrate (0.02 mol) and gallium(III) nitrate hydrate (0.01 mol). This yielded a blue solution. This solution was evaporated and dried under vacuum to obtain [Cu2Ga(MeCOO)6(H2O)3]. A 15 mL aqueous solution of [Cu2Ga(MeCOO)6(H2O)3] (1.75 mmol) was mixed with Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6). 37The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37 A pale green precipitate of {Cu2Ga(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 48%).

[0133] Example 2: {SiW9O} as a cesium salt 37 [Cu2Zn(L)]3} 10- Synthesis of (L=H2O or OAc - ):

[0134] A 70 mL aqueous solution of sodium acetate trihydrate (0.32 mol) was added to a 70 mL filtered and stirred solution of copper(II) nitrate trihydrate (0.02 mol) and zinc(II) nitrate hexahydrate (0.01 mol). This yielded a blue solution. This solution was evaporated and dried under vacuum to obtain [Cu2Zn(MeCOO)6(H2O)3]. A 15 mL aqueous solution of [Cu2Zn(MeCOO)6(H2O)3] (1.75 mmol) was mixed with Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6). 37 The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37 A pale green precipitate of {Cu2Zn(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 57%).

[0135] Example 3: {SiW9O} as a cesium salt 37 [Cu2Sn(L)]3} 8- Synthesis of (L=H2O or OAc - ):

[0136] A 70 mL aqueous solution of sodium acetate trihydrate (0.32 mol) was added to a 70 mL filtered and stirred solution of copper(II) nitrate trihydrate (0.02 mol) and tin(IV) acetate trihydrate (0.01 mol). This yielded a blue solution. This solution was evaporated and dried under vacuum to obtain [Cu2Sn(MeCOO)6(H2O)3]. A 15 mL aqueous solution of [Cu2Sn(MeCOO)6(H2O)3] (1.75 mmol) was mixed with Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6). 37 The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37 A pale green precipitate of {Cu2Sn(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 49%).

[0137] Example 4: {SiW9O} as a cesium salt 37 [Cu2Al(L)]3} 9- Synthesis of (L=H2O or OAc - ):

[0138] A 70 mL aqueous solution of sodium acetate trihydrate (0.32 mol) was added to a 70 mL filtered and stirred solution of copper(II) nitrate trihydrate (0.02 mol) and anhydrous aluminum(III) nitrate (0.01 mol). This yielded a blue solution. This solution was evaporated and dried under vacuum to obtain [Cu2Al(MeCOO)6(H2O)3]. A 15 mL aqueous solution of [Cu2Al(MeCOO)6(H2O)3] (1.75 mmol) was mixed with Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6). 37 The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37 A pale green precipitate of {Cu2Al(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 51%).

[0139] Example 5: {SiW9O} as a cesium salt 37 [Cu2Sc(L)]3} 9- Synthesis of (L=H2O or OAc - ):

[0140] A 70 mL aqueous solution of sodium acetate trihydrate (0.32 mol) was added to a 70 mL filtered and stirred solution of copper(II) nitrate trihydrate (0.02 mol) and cadmium(III) nitrate hexahydrate (0.01 mol). This yielded a blue solution. This solution was evaporated and dried under vacuum to obtain [Cu2Sc(MeCOO)6(H2O)3]. A 15 mL aqueous solution of [Cu2Sc(MeCOO)6(H2O)3] (1.75 mmol) was mixed with Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6). 37The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37 A pale green precipitate of {Cu2Sc(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 36%).

[0141] Example 6: {SiW9O} as a cesium salt 37 [Cu2Mg(L)]3} 10- Synthesis of (L=H2O or OAc - ):

[0142] A 70 mL aqueous solution of sodium acetate trihydrate (0.32 mol) was added to a 70 mL filtered and stirred solution of copper(II) nitrate trihydrate (0.02 mol) and magnesium(II) nitrate hexahydrate (0.01 mol). This yielded a pale blue solution. This solution was evaporated and dried under vacuum to obtain [Cu2Mg(MeCOO)6(H2O)3]. A 15 mL aqueous solution of [Cu2Mg(MeCOO)6(H2O)3] (1.75 mmol) was mixed with Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6). 37 The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37 A pale green precipitate of {Cu2Mg(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 35%).

[0143] Example 7: {SiW9O} as a cesium salt 37 [CuFeNi(L)]3} 9- Synthesis of (L=H2O or OAc - ):

[0144] A 70 mL solution of copper(II) nitrate trihydrate (0.01 mol), iron(III) nitrate unhydrate (0.01 mol), and nickel(II) nitrate hexahydrate (0.01 mol) was filtered and stirred, to which an aqueous solution of sodium acetate trihydrate (0.32 mol) (70 mL) was added. This yielded a yellowish-green solution. This solution was evaporated and dried under vacuum to obtain [CuFeNi(MeCOO)6(H2O)3]. An aqueous solution of [CuFeNi(MeCOO)6(H2O)3] (1.75 mmol) (15 mL) was mixed with Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6). 37 The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37 A pale green precipitate of {CuFeNi(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 47%).

[0145] Example 8: {SiW9O} as a cesium salt 37 [CuFeZn(L)]3} 9- Synthesis of (L=H2O or OAc - ):

[0146] A 70 ml solution of copper(II) nitrate trihydrate (0.01 mol), iron(III) nitrate unhydrate (0.01 mol), and zinc(II) nitrate hexahydrate (0.01 mol) was filtered and stirred, to which an aqueous solution of sodium acetate trihydrate (0.32 mol) (70 ml) was added. This yielded a brown solution. This solution was evaporated and dried under vacuum to obtain [CuFeZn(MeCOO)6(H2O)3].

[0147] In an aqueous solution (15 mL) of [CuFeZn(MeCOO)6(H2O)3] (1.75 mmol), Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6) was added. 37 The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37 A pale green precipitate of {CuFeZn(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 37%).

[0148] Example 9: {SiW9O} as a cesium salt 37 [CuFeAl(L)]3} 8- Synthesis of (L=H2O or OAc - ):

[0149] A 70 mL solution of copper(II) nitrate trihydrate (0.01 mol), anhydrous iron(III) nitrate (0.01 mol), and anhydrous aluminum(III) nitrate (0.01 mol) was filtered and stirred, to which an aqueous solution of sodium acetate trihydrate (0.32 mol) (70 mL) was added. This yielded a greenish-brown solution. This solution was evaporated and dried under vacuum to obtain [CuFeAl(MeCOO)6(H2O)3]. An aqueous solution of [CuFeAl(MeCOO)6(H2O)3] (1.75 mmol) (15 mL) was mixed with Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6). 37 The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37 A pale green precipitate of {CuFeAl(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 54%).

[0150] Example 10: {SiW9O} as a cesium salt 37 [CuNiZn(L)]3} 10- Synthesis of (L=H2O or OAc - ):

[0151] A 70 ml solution of copper(II) nitrate trihydrate (0.01 mol), nickel(II) nitrate hexahydrate (0.01 mol), and zinc(II) nitrate hexahydrate (0.01 mol) was filtered and stirred, to which an aqueous solution of sodium acetate trihydrate (0.32 mol) (70 ml) was added. This yielded a blue solution. This solution was evaporated and dried under vacuum to obtain [CuNiZn(MeCOO)6(H2O)3].

[0152] In an aqueous solution (15 mL) of [CuNiZn(MeCOO)6(H2O)3] (1.75 mmol), Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6) was added. 37 The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37 A pale green precipitate of {CuNiZn(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 52%).

[0153] Example 11: {SiW9O} as a cesium salt 37 [CuNiAl(L)]3} 9- Synthesis of (L=H2O or OAc - ):

[0154] A 70 ml solution of copper(II) nitrate trihydrate (0.01 mol), nickel(II) nitrate hexahydrate (0.01 mol), and anhydrous aluminum(III) nitrate (0.01 mol) was filtered and stirred, to which an aqueous solution of sodium acetate trihydrate (0.32 mol) (70 mL) was added. This yielded a blue solution. This solution was evaporated and dried under vacuum to obtain [CuNiAl(MeCOO)6(H2O)3]. An aqueous solution of [CuNiAl(MeCOO)6(H2O)3] (1.75 mmol) (15 mL) was mixed with Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6). 37The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37 A pale green precipitate of {CuNiAl(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 49%).

[0155] Example 12: {SiW9O} as a cesium salt 37 [CuFeGa(L)]3} 8- Synthesis of (L=H2O or OAc - ):

[0156] A 70 ml solution of copper(II) nitrate trihydrate (0.01 mol), iron(III) nitrate unhydrate (0.01 mol), and gallium(II) nitrate (0.01 mol) was filtered and stirred, to which an aqueous solution of sodium acetate trihydrate (0.32 mol) (70 ml) was added. This solution was evaporated and dried under vacuum to obtain [CuFeGa(MeCOO)6(H2O)3].

[0157] In an aqueous solution (15 mL) of [CuFeGa(MeCOO)6(H2O)3] (1.75 mmol), Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6) was added. 37 The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37A pale green precipitate of {CuFeGa(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 47%).

[0158] Example 13: {SiW9O} as a cesium salt 37 [CuFeSn(L)]3} 7- Synthesis of (L=H2O or OAc - ):

[0159] A 70 mL solution of copper(II) nitrate trihydrate (0.01 mol), anhydrous iron(III) nitrate (0.01 mol), and tin(IV) acetate (0.01 mol) was filtered and stirred, to which an aqueous solution of sodium acetate trihydrate (0.32 mol) (70 mL) was added. This solution was evaporated and dried under vacuum to obtain [CuFeSn(MeCOO)6(H2O)3].

[0160] In an aqueous solution (15 mL) of [CuFeSn(MeCOO)6(H2O)3] (1.75 mmol), Na9[β-SiW9O] dissolved in NaOAc / HOAc solution (pH 6) was added. 37 The mixture was gradually added with vigorous stirring while adding CsCl (0.33 g / ml) solution at room temperature, and the mixture was heated at 50°C for 1 hour. 37 A pale green precipitate of {CuFeSn(L)3} was formed. This compound was characterized by infrared spectroscopy and high-resolution mass spectrometry (yield 36%).

[0161] Example 14: Typical exchange between alkali metal cations and quaternary ammonium cations:

[0162] Cs 10 [SiCu3(H2O)3W9O 37](300 mg) was dissolved in 50 mL of deionized water in a beaker. Tetrahexylammonium bromide (3.6 g) was dissolved in 100 mL of dichloromethane and sonicated for 15 minutes. When these two solutions were mixed, two separate phases were formed: the upper phase was an aqueous phase, and the lower phase was [(n-hexyl)4N] 10 [SiCu3(H2O)3W9O 37 The oily phase contained [ ] (extracted and washed several times with deionized water). The clear solution was then evaporated to dryness.

[0163] Example 15: CO2 reduction in non-divided cells:

[0164] Titanium metal working electrode, carbon cloth counter electrode, Nafion membrane, and 2 mM [(n-hexyl)4N] as supporting electrolyte in acetonitrile. n [SiM a M b M c (L a L b L c )W9O 37 In an electrolytic cell (Figure 2) containing 0.1 M (n-butyl)4NPF6 (prepared as detailed in Example 14), constant potential electrolysis was performed at room temperature for 1 hour. Six types of [SiM a M b M c (H2O)3W9O 37 ] n- The table below shows the amount of CO produced and the Faraday efficiency (FE) for CO production for each anion.

[0165] [Table 1]

[0166] While specific features of the present invention have been illustrated and described herein, various modifications, substitutions, alterations, and equivalents may be conceivable to those skilled in the art. Therefore, it should be understood that the appended claims are intended to encompass all such modifications and alterations that fall within the scope of the present invention.

Claims

1. A polyoxometalate compound represented by the following formula (I) or its solvate. (Q) ｎ [XM ａ M ｂ M ｃ (L ａ )(L ｂ )(L ｃ )W ９ O ３７ ] (I) During the ceremony, X is either P or Si. M ａ M ｂ , and M ｃ Each element is independently selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Sn, Sb, In, Sc, Sr, Mg, Y, Yb, Ba, and Ca, and at least one of Ma, Mb, and Mc is Cu. L ａ , L ｂ , and L ｃ H ２ It is either oxygen or a carboxylate salt. Q is a cation selected from the group consisting of alkali metal cations, alkaline earth metal cations, lanthanide cations, nitrogen-centered cations, phosphorus-centered cations, and any combination thereof. n is an integer between 4 and 13.

2. The compound according to claim 1, Q is a compound that is a quaternary ammonium cation.

3. A compound according to claim 1 or 2, M ａ M ｂ , and M ｃ These are different compounds.

4. A compound according to claim 1 or 2, M ａ M ｂ , and M ｃ A compound in which at least one of the elements is Sn, Al, Zn, or Ga.

5. A compound according to claim 1 or 2, The compound in question is (Q)n[XCu ２ M'L ａ L ｂ LcW ９ O ３７ ] and M'' is a compound selected from the group consisting of Sn, Zn, Al, and Ga.

6. A compound according to claim 1 or 2, When the compound is (Q) ｎ [XCu ２ ZnL ａ L ｂ L ｃ W ９ O ３７ , (Q) ｎ [XCu ２ GaL ａ L ｂ L ｃ W ９ O ３７ , (Q) ｎ [XCu ２ SnL ａ L ｂ L ｃ W ９ O ３７ , (Q) ｎ [XCu ２ AlL ａ L ｂ L ｃ W ９ O ３７ , (Q) ｎ [XCuFeZnL ａ L ｂ L ｃ W ９ O ３７ , (Q) ｎ [XCuFeNiL ａ L ｂ L ｃ W ９ O ３７ , (Q) ｎ [XCuFeAlL ａ L ｂ L ｃ W ９ O ３７ , (Q) ｎ [XCuNiZnL ａ L ｂ L ｃ W ９ O ３７ , (Q) ｎ [XCuNiAlL ａ L ｂ L ｃ W ９ O ３７ , (Q) n [XCuFeGaLaLbLcW9O37], (Q) ｎ [XCuCoZnL ａ L 说明:原文中 ２ 疑似多了一个0,已按正确格式翻译。如果原文无误,请告知我,我会进行相应修改。 ｂ L ｃ W ９ O ３７ , (Q) ｎ [XCuCoAlL ａ L ｂ L ｃ W ９ O ３７ , (Q) ｎ [XCuMnZnL ａ L ｂ L ｃ W ９ O ３７ , or, (Q) ｎ [XCuMnAlL ａ L ｂ L ｃ W ９ O ３７ , is a compound.

7. The compound according to claim 1, Q is a compound that is a quaternary ammonium, pyridinium, or imidazolium cation.

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