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Abstract
Abstract
Recent developments in polyoxometalate photochemistry are discussed with a focus on visible light driven productive chemical reactions. Special attention is given to the fundamental photochemistry of polyoxometalates and the effects on the
resulting photoprocesses.
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Panagiotopoulos A, Douvas AM, Argitis P, Coutsolelos AG. Porphyrin-Sensitized Evolution of Hydrogen using Dawson and Keplerate Polyoxometalate Photocatalysts. CHEMSUSCHEM 2016; 9:3213-3219. [PMID: 27775226 DOI: 10.1002/cssc.201600995] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/01/2016] [Indexed: 06/06/2023]
Abstract
Hydrogen evolution using photocatalytic systems based on artificial photosynthesis is a major approach toward solar energy conversion and storage. In the polyoxometalate-based photocatalytic systems proposed in the past, middle/near UV light irradiation and noble-metal catalysts were mainly used. Although recently polyoxometalates were sensitized in visible light, photosensitizers or catalysts based on noble metals, and/or poor activity of polyoxometalates were generally obtained. Here we show the highly efficient [turnover number (TON)=215] hydrogen evolution induced by the zinc(II) mesotetrakis(N-methyl-pyridinium-4-yl)porphyrin (ZnTMPyP4+ ) sensitization of a series of polyoxometalate catalysts (two Dawson type, P2 Mo18 O626- and P2 W18 O626- anions, and one Keplerate {Mo132 } cluster) in a visible-light-driven, noble-metal-free, and fully water-soluble system. We attributed the high efficiency for hydrogen evolution to the multi-electron reduction of polyoxometalates and found that: (a) both Dawson polyoxometalates exhibit higher hydrogen evolution efficiency upon ZnTMPyP4+ sensitization in relation to the direct photoreduction of those compounds; (b) the P2 Mo18 O626- anion is more efficient (TON=65 vs. 38, respectively) for hydrogen evolution than the P2 W18 O626- anion; and (c) the high nuclearity Keplerate {Mo132 } cluster exhibits the highest efficiency (TON=215) for hydrogen evolution compared with the polyoxometalates studied.
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Affiliation(s)
- Athanassios Panagiotopoulos
- Laboratory of Bioinorganic Chemistry, Department of Chemistry, University of Crete, Voutes Campus, 70013, Heraklion, Crete, Greece
| | - Antonios M Douvas
- Institute of Nanoscience and Nanotechnology (INN), National Center for Scientific Research (NCSR) "Demokritos", Patr. Gregoriou E' & 27, Neapoleos str., 153 41, Agia Paraskevi, Attica, Greece
| | - Panagiotis Argitis
- Institute of Nanoscience and Nanotechnology (INN), National Center for Scientific Research (NCSR) "Demokritos", Patr. Gregoriou E' & 27, Neapoleos str., 153 41, Agia Paraskevi, Attica, Greece
| | - Athanassios G Coutsolelos
- Laboratory of Bioinorganic Chemistry, Department of Chemistry, University of Crete, Voutes Campus, 70013, Heraklion, Crete, Greece
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Sivakumar R, Thomas J, Yoon M. Polyoxometalate-based molecular/nano composites: Advances in environmental remediation by photocatalysis and biomimetic approaches to solar energy conversion. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2012. [DOI: 10.1016/j.jphotochemrev.2012.08.001] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Photochemical oxidation of water and reduction of polyoxometalate anions at interfaces of water with ionic liquids or diethylether. Proc Natl Acad Sci U S A 2012; 109:11552-7. [PMID: 22753501 DOI: 10.1073/pnas.1203818109] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Photoreduction of [P(2)W(18)O(62)](6-), [S(2)Mo(18)O(62)](4-), and [S(2)W(18)O(62)](4-) polyoxometalate anions (POMs) and oxidation of water occurs when water-ionic liquid and water-diethylether interfaces are irradiated with white light (275-750 nm) or sunlight. The ionic liquids (ILs) employed were aprotic ([Bmim]X; Bmim = (1-butyl-3-methylimidazolium, X = BF(4), PF(6)) and protic (DEAS = diethanolamine hydrogen sulphate; DEAP = diethanolamine hydrogen phosphate). Photochemical formation of reduced POMs at both thermodynamically stable and unstable water-IL interfaces led to their initial diffusion into the aqueous phase and subsequent extraction into the IL phase. The mass transport was monitored visually by color change and by steady-state voltammetry at microelectrodes placed near the interface and in the bulk solution phases. However, no diffusion into the organic phase was observed when [P(2)W(18)O(62)](6-) was photo-reduced at the water-diethylether interface. In all cases, water acted as the electron donor to give the overall process: 4POM + 2H(2)O + hν → 4POM(-) + 4H(+) + O(2). However, more highly reduced POM species are likely to be generated as intermediates. The rate of diffusion of photo-generated POM(-) was dependent on the initial concentration of oxidized POM and the viscosity of the IL (or mixed phase system produced in cases in which the interface is thermodynamically unstable). In the water-DEAS system, the evolution of dioxygen was monitored in situ in the aqueous phase by using a Clark-type oxygen sensor. Differences in the structures of bulk and interfacial water are implicated in the activation of water. An analogous series of reactions occurred upon irradiation of solid POM salts in the presence of water vapor.
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Streb C. New trends in polyoxometalate photoredox chemistry: From photosensitisation to water oxidation catalysis. Dalton Trans 2012; 41:1651-9. [DOI: 10.1039/c1dt11220a] [Citation(s) in RCA: 214] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Reactivity of one-, two-, three- and four-electron reduced forms of α-[P2W18O62]6− generated by controlled potential electrolysis in water. Inorganica Chim Acta 2011. [DOI: 10.1016/j.ica.2011.02.049] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Bernardini G, Zhao C, Wedd AG, Bond AM. Ionic Liquid-Enhanced Photooxidation of Water Using the Polyoxometalate Anion [P2W18O62]6– as the Sensitizer. Inorg Chem 2011; 50:5899-909. [DOI: 10.1021/ic1016627] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
| | | | - Anthony G. Wedd
- School of Chemistry and the Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Victoria 3010, Australia
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Forster J, Rösner B, Khusniyarov MM, Streb C. Tuning the light absorption of a molecular vanadium oxide system for enhanced photooxidation performance. Chem Commun (Camb) 2011; 47:3114-6. [DOI: 10.1039/c0cc05536k] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Douvas AM, Kapella A, Dimotikali D, Argitis P. Photochemically-Induced Acid Generation from 18-Molybdodiphosphate and 18-Tungstodiphosphate within Poly(2-Hydroxyethyl Methacrylate) Films. Inorg Chem 2009; 48:4896-907. [DOI: 10.1021/ic900295n] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Antonios M. Douvas
- Institute of Microelectronics, National Center for Scientific Research “Demokritos”, 15310 Aghia Paraskevi, Athens, Greece
| | - Anna Kapella
- Institute of Microelectronics, National Center for Scientific Research “Demokritos”, 15310 Aghia Paraskevi, Athens, Greece
- Department of Chemical Engineering, National Technical University of Athens, 15780 Zographou, Athens, Greece
| | - Dimitra Dimotikali
- Department of Chemical Engineering, National Technical University of Athens, 15780 Zographou, Athens, Greece
| | - Panagiotis Argitis
- Institute of Microelectronics, National Center for Scientific Research “Demokritos”, 15310 Aghia Paraskevi, Athens, Greece
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Affiliation(s)
- Arthur J. Esswein
- Department of Chemistry 6-335, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307
| | - Daniel G. Nocera
- Department of Chemistry 6-335, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307
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Rüther T, Hultgren VM, Timko BP, Bond AM, Jackson WR, Wedd AG. Electrochemical investigation of photooxidation processes promoted by sulfo-polyoxometalates: coupling of photochemical and electrochemical processes into an effective catalytic cycle. J Am Chem Soc 2003; 125:10133-43. [PMID: 12914478 DOI: 10.1021/ja029348f] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Oxidative photocurrents measured upon irradiation by a 7-W visible light (wavelength 312-700 nm) demonstrated that the sulfo-polyoxometalate anion clusters [S2W18O62]4- (1a), [S2Mo18O62]4- (1b), and [SMo12O40]2- (2) may be activated photochemically to oxidize the organic substrates benzyl alcohol, ethanol, and (-)-menthol. In the case of catalytic photooxidation of benzyl alcohol to benzaldehyde in the presence of 1a, quantitative electrochemical methods have identified pathways for the oxidation of reduced forms of 1 generated during the catalysis. More generally, the oxidation pathways P(n+2)- + 2H+ <==> Pn- + H2 and 2P(n+2)- + O2 + 4H+ <==> 2Pn- + 2H2O have been evaluated by monitoring acidified acetonitrile solutions of the 2e(-)-reduced clusters by rotating disk electrode voltammetry under anaerobic and aerobic conditions, respectively. Neither of the reduced forms 1b(2e-) nor 2(2e-) reacted under these conditions. In contrast, 1a(2e-) was oxidized via both pathways, consistent with its more negative redox potential, with the rate of oxidation by air-oxygen being significantly faster than that by H+. The present work demonstrated that the crucial step necessary to oxidize reduced catalyst in photocatalytic reactions involving the anions studied may be achieved or accelerated by application of an external potential more positive than the first redox potential of the polyoxometalate anion. Voltammetric analysis revealed that this in situ electrolytic regeneration of the reduced catalyst is an option that leads to a viable photoelectrocatalytic pathway, even when the H+ and O2 pathways are not available.
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Affiliation(s)
- Thomas Rüther
- Centre for Green Chemistry, Monash University, Box 23, Melbourne, Victoria 3800, Australia
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Baker LCW, Glick DC. Present General Status of Understanding of Heteropoly Electrolytes and a Tracing of Some Major Highlights in the History of Their Elucidation. Chem Rev 1998; 98:3-50. [PMID: 11851498 DOI: 10.1021/cr960392l] [Citation(s) in RCA: 355] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Louis C. W. Baker
- Department of Chemistry, Georgetown University, Washington, D.C. 20057
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Papadakis A, Souliotis A, Papaconstantinou E. Functionalization of electrodes with polyoxometalates P2Mo18O626− and P2W18O626−. J Electroanal Chem (Lausanne) 1997. [DOI: 10.1016/s0022-0728(97)00017-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Formation of molecular hydrogen in photocatalytic systems containing heteropolytungstates as electron carriers. THEOR EXP CHEM+ 1995. [DOI: 10.1007/bf00534663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Hiskia A, Papaconstantinou E. Selective photocatalytic oxidation of alcohols by heteropolytungstates. Polyhedron 1988. [DOI: 10.1016/s0277-5387(00)81194-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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