137 results on '"Caramori, S."'
Search Results
2. Operando double-edge high-resolution X-ray absorption spectroscopy study of BiVO4 photoanodes
- Author
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Piccioni, A., Kesavan, J. K., (0000-0003-2234-4173) Amidani, L., Mazzaro, R., Berardi, S., Caramori, S., Pasquini, L., Boscherini, F., Piccioni, A., Kesavan, J. K., (0000-0003-2234-4173) Amidani, L., Mazzaro, R., Berardi, S., Caramori, S., Pasquini, L., and Boscherini, F.
- Abstract
High energy resolution fluorescence detected X-ray absorption spectroscopy is a powerful method for probing the electronic structure of functional materials. The X-ray penetration depth and photon-in/photon-out nature of the method allow operando experiments to be performed, in particular in electrochemical cells. Here, operando high-resolution X-ray absorption measurements of a BiVO4 photoanode are reported, simultaneously probing the local electronic states of both cations. Small but significant variations of the spectral lineshapes induced by the applied potential were observed and an explanation in terms of the occupation of electronic states at or near the band edges is proposed.
- Published
- 2024
3. Nanostructured metal oxide semiconductors for photoelectrocatalytic conversion of solar energy
- Author
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Vecchi, P., primary, Piccioni, A., additional, Carrai, I., additional, Mazzaro, R., additional, Boscherini, F., additional, Ceroni, P., additional, Caramori, S., additional, and Pasquini, L., additional
- Published
- 2023
- Full Text
- View/download PDF
4. Emerging Contaminants Mineralization by a Photo-Electrochemical Method Based on WO3
- Author
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Molinari, A., Longobucco, G., Pasti, L., Cristino, V., Caramori, S., Bignozzi, C. A., di Prisco, Marco, Series editor, Chen, Sheng-Hong, Series editor, Solari, Giovanni, Series editor, Vayas, Ioannis, Series editor, and Mannina, Giorgio, editor
- Published
- 2017
- Full Text
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5. Searching for new redox-complexes\in organic flow batteries
- Author
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Meda, L., Oldani, F., Tozzola, G., Caramori, S., Benazzi, E., Cristino, V., and Bignozzi, C.A.
- Published
- 2018
- Full Text
- View/download PDF
6. Hancornia speciosa serum latex fraction: a non-allergenic biomaterial
- Author
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Costa, A. F., primary, Gonçalves, K. C., additional, Bailão, E. F. L. C., additional, Caramori, S. S., additional, Valadares, M. C., additional, Gonçalves, P. J., additional, and Almeida, L. M., additional
- Published
- 2023
- Full Text
- View/download PDF
7. The role of transition metal complexes in dye sensitized solar devices
- Author
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Bignozzi, C.A., Argazzi, R., Boaretto, R., Busatto, E., Carli, S., Ronconi, F., and Caramori, S.
- Published
- 2013
- Full Text
- View/download PDF
8. Efficient Anodically Grown WO3 for Photoelectrochemical Water Splitting
- Author
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Caramori, S., Cristino, V., Meda, L., Tacca, A., Argazzi, R., and Bignozzi, C.A.
- Published
- 2012
- Full Text
- View/download PDF
9. Removal of poly- and perfluoroalkyl substances (PFAS) from aqueous matrix by using hydrogel containing nanostructured carbon material
- Author
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Stevanin, C., Boaretto, R., Chenet, T., Cescon, M., Caramori, S., and Pasti, L.
- Subjects
Ambientale - Published
- 2021
10. Publisher Correction: Hierarchical organization of perylene bisimides and polyoxometalates for photo-assisted water oxidation (Nature Chemistry, (2019), 11, 2, (146-153), 10.1038/s41557-018-0172-y)
- Author
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Bonchio, M., Syrgiannis, Z., Burian, M., Marino, N., Pizzolato, E., Dirian, K., Rigodanza, F., Volpato, G. A., La Ganga, G., Demitri, N., Berardi, S., Amenitsch, H., Guldi, D. M., Caramori, S., Bignozzi, C. A., Sartorel, A., Prato, M., Bonchio, M., Syrgiannis, Z., Burian, M., Marino, N., Pizzolato, E., Dirian, K., Rigodanza, F., Volpato, G. A., La Ganga, G., Demitri, N., Berardi, S., Amenitsch, H., Guldi, D. M., Caramori, S., Bignozzi, C. A., Sartorel, A., and Prato, M.
- Subjects
water oxidation ,polyoxometalate ,perylene bisimides ,perylene bisimides, polyoxometalate, water oxidation - Abstract
The oxygen in Earth’s atmosphere is there primarily because of water oxidation performed by photosynthetic organisms using solar light and one specialized protein complex, photosystem II (PSII). High-resolution imaging of the PSII ‘core’ complex shows the ideal co-localization of multi-chromophore light-harvesting antennas with the functional reaction centre. Man-made systems are still far from replicating the complexity of PSII, as the majority of PSII mimetics have been limited to photocatalytic dyads based on a 1:1 ratio of a light absorber, generally a Ru–polypyridine complex, with a water oxidation catalyst. Here we report the self-assembly of multi-perylene-bisimide chromophores (PBI) shaped to function by interaction with a polyoxometalate water-oxidation catalyst (Ru4POM). The resulting [PBI]5Ru4POM complex shows a robust amphiphilic structure and dynamic aggregation into large two-dimensional paracrystalline domains, a redshifted light-harvesting efficiency of >40% and favourable exciton accumulation, with a peak quantum efficiency using ‘green’ photons (λ > 500 nm). The modularity of the building blocks and the simplicity of the non-covalent chemistry offer opportunities for innovation in artificial photosynthesis.
- Published
- 2019
11. Photoelectrocatalytic degradation of emerging contaminants at WO₃/BiVO₄ photoanodes in aqueous solution
- Author
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Cristino, V., Pasti, L., Marchetti, N., Berardi, S., Bignozzi, C. A., Molinari, A., Passabi, F., Caramori, S., Amidani, L., Orlandi, M., Bazzanella, N., Piccioni, A., Kesavan, J. K., Boscherini, F., and Pasquini, L.
- Abstract
WO3/BiVO4 films obtained by electrochemical deposition of BiVO4 over mesoporous WO3 were applied to the photoelectrochemical degradation of selected emerging contaminants (ketoprofen and levofloxacine) in aqueous solutions. The WO3/BiVO4 films in this work are characterized by a mesoporous morphology with a maximum photoconversion efficiency >40% extending beyond 500 nm in Na2SO4 electrolytes. Oxygen was found to be the dominant water oxidation product (ca. 90% faradaic yield) and no evidence for the photogeneration of OH radicals was obtained. Nevertheless, both 10 ppm levofloxacine and ketoprofen could be degraded at WO3/BiVO4 junctions upon a few hours of illumination under visible light. However, while levofloxacine degradation intermediates were progressively consumed by further oxidation at the WO3/BiVO4 interface, ketoprofen oxidation byproducts, being stable aromatic species, were found to be persistent in aqueous solution even after 15 hours of solar simulated illumination. This indicates that, due to the lower oxidizing power of photogenerated holes in BiVO4 and a different water oxidation mechanism, the employment of WO3/BiVO4 in photoelectrochemical environmental remediation processes is much less universal than that possible with wider band gap semiconductors such as TiO2 and WO3.
- Published
- 2019
12. Sensitization of TiO 2 with ruthenium complexes containing boronic acid functions
- Author
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Altobello, S, Bignozzi, C.A, Caramori, S, Larramona, G, Quici, Silvio, Marzanni, Giovanni, and Lakhmiri, Rajae
- Published
- 2004
- Full Text
- View/download PDF
13. Efficient osmium sensitizers containing 2,2′-bipyridine-4,4′-bisphosphonic acid ligand
- Author
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Zabri, Hervé, Odobel, Fabrice, Altobello, S., Caramori, S., and Bignozzi, C.A.
- Published
- 2004
- Full Text
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14. A Modular Stand-Alone Photocatalytic Reactor for Waste Water Purification: The HPSolar Project
- Author
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Bernardoni, P., Boschetti, M., Mangherini, G., Vincenzi, D., Fugattini, S., Andreoli, A., Cristino, V., Caramori, S., and Bignozzi, C.A.
- Subjects
PV Systems - Performance, Applications and Integration ,Grid and Energy System Integration ,Stand-Alone PV System ,Stand-Alone PV System, Off-Grid, Utilities ,Ambientale ,Off-Grid ,Utilities - Abstract
35th European Photovoltaic Solar Energy Conference and Exhibition; 1750-1753, In this work we present the construction and performances of a photocatalytic reactor developed for the HPSolar project, the purpose of this reactor is the treatment of water in order to remove pollutants like drugs or pesticides that are not removed effectively by present water treatments. The reactor is modular and composed by multiple elementary cells where the photocatalyst is a thin layer of tungsten trioxide biased positively with respect to a metallic cathode; this polarization is switched periodically in order to restore the functionality of the anode. The cells are completely self-reliant because are powered by four solar cells laying behind the semi-transparent anode while a microcontroller integrated into each cell applies the biasing cycles. The abatement measurements on atenolol and carbamazepine show that this device can remove 70% of the drugs from a sample of water within 5 and 7 hours respectively.
- Published
- 2018
15. Could Fidicina mannifera (Hemiptera: Cicadoidea: Fidicinini) promote a resource pulse in two Brazilian Cerrado vegetation classes?
- Author
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Oliveira, R. N., primary, Caramori, S. S., additional, and Maccagnan, D. H. B., additional
- Published
- 2017
- Full Text
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16. A new ruthenium black dye design with improved optical properties for transparent dye sensitized solar devices
- Author
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Boaretto, R., primary, Carli, S., additional, Caramori, S., additional, Bignozzi, C. A., additional, Saccone, D., additional, Magistris, C., additional, Barolo, C., additional, and Viscardi, G., additional
- Published
- 2017
- Full Text
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17. A photoelectrochemical investigation of push-pull Zn(II) porphyrins as potential photosensitizers for dye-sensitized solar cells
- Author
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Orbelli Biroli, A., Tessore, F., Ugo, R., De Angelis, F., Giorgi, G., Bignozzi, C. A., Caramori, S., and Pizzotti, M.
- Subjects
Zinc ,Push-pull porphyrin ,Photosensitizer ,DSSC - Published
- 2010
18. Zn(II) porphyrinic photosensitizer for DSSC
- Author
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Biaggi, C., Orbelli Biroli, A., Pizzotti, M., Tessore, F., Ugo, R., De Angelis, F., Giorgi, G., Bignozzi, C. A., and Caramori, S.
- Subjects
Zinc ,Push-pull porphyrin ,Photosensitizer ,DSSC - Published
- 2010
19. Functional nanomaterials based on wide band gap semiconductors. Applications in photoelectrochemical, electrochromic and photochromic devices
- Author
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Argazzi, R., Biancardo, M., Caramori, S., and Bignozzi, C.A.
- Subjects
7-I poly - Published
- 2005
20. Micro-Raman analysis of reverse bias stressed dye-sensitized solar cells
- Author
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Agresti, A., primary, Pescetelli, S., additional, Quatela, A., additional, Mastroianni, S., additional, Brown, T. M., additional, Reale, A., additional, Bignozzi, C. A., additional, Caramori, S., additional, and Di Carlo, A., additional
- Published
- 2014
- Full Text
- View/download PDF
21. On the effect of Al2O3 blocking layer on the performance of dye solar cells with cobalt based electrolytes
- Author
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Liberatore, M., primary, Burtone, L., additional, Brown, T. M., additional, Reale, A., additional, Di Carlo, A., additional, Decker, F., additional, Caramori, S., additional, and Bignozzi, C. A., additional
- Published
- 2009
- Full Text
- View/download PDF
22. Sensitization of TiO2 with ruthenium complexes containing boronic acid functions
- Author
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Altobello, S, primary, Bignozzi, C.A, additional, Caramori, S, additional, Larramona, G, additional, Quici, Silvio, additional, Marzanni, Giovanni, additional, and Lakhmiri, Rajae, additional
- Published
- 2004
- Full Text
- View/download PDF
23. Efficient Anodically Grown WO3 for Photoelectrochemical Water Splitting.
- Author
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Caramori, S., Cristino, V., Meda, L., Tacca, A., Argazzi, R., and Bignozzi, C.A.
- Subjects
TUNGSTEN oxides ,CRYSTAL growth ,PHOTOELECTROCHEMISTRY ,WATER ,CHEMICAL reactions ,SOLVENTS ,POTENTIOSTAT ,ELECTROLYTES ,SIMULATION methods & models - Abstract
Abstract: The potentiostatic anodization of metallic tungsten has been investigated in different solvent/electrolyte compositions with the aim of improving the photoelectrochemical performances of the tungsten oxide layer. Among the explored electrolytes, the anodization in the NMF/H2O/NH4F solvent mixture was found to produce the most efficient WO3 photoanodes, which, combining spectral sensitivity, high electrochemically active surface and improved charge transfer kinetics, outperform, under simulated solar illumination, most of the reported nanocrystalline substrates produced by anodization in aqueous electrolytes and by sol gel methods. While the preparation of the photoelectrodes is a slow process at room temperature (20°C), it could be greatly accelerated (x 10) by carrying out the anodization at 40-50°C, thus proving to be a fast and convenient approach to the production of high performing WO3 photoactive substrates directly connected to a metal electron collector. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
24. Indium Tin Oxide Electrodes Modified with Tris(2,2-bipyridine-4,4-dicarboxylic acid) Iron(II) and the Catalytic Oxidation of Tris(4,4-di-tert-butyl-2,2-bipyridine) Cobalt(II)
- Author
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Elliott, C. M., Caramori, S., and Bignozzi, C. A.
- Abstract
Indium tin oxide (ITO) electrodes modified by attachment of tris(2,2-bipyridine-4,4-dicarboxylic acid) iron(II) are examined. The mode of attachment is believed to be via the COOH functions in a manner similar to attachment of similar carboxylate-containing compounds to TiO
2 surfaces. On the surface the complex resides as a stable electrochemically active monolayer. These modified electrodes can efficiently catalyze the oxidation of certain cobalt complexes, specifically, tris(4,4-di-tert-butyl-2,2-bipyridine) cobalt(II). On the unmodified ITO surfaces this cobalt complex is essentially electrochemically inert. The catalytic process approaches diffusional control at very slow scan speeds. Also, the electro-catalysis is sufficiently efficient that the peak oxidation current for Co2+, under certain conditions, exceeds the ip for the surface oxidation of the adsorbed Fe2+ by >×100 and the current for the uncatalyzed oxidation of Co2+ by considerably more than that.- Published
- 2005
25. On the effect of Al2O3 blocking layer on the performance of dye solar cells with cobalt based electrolytes.
- Author
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Liberatore, M., Burtone, L., Brown, T. M., Reale, A., Di Carlo, A., Decker, F., Caramori, S., and Bignozzi, C. A.
- Subjects
DYE-sensitized solar cells ,ELECTROLYTES ,IMPEDANCE spectroscopy ,TITANIUM dioxide ,SUBSTRATES (Materials science) - Abstract
Dye solar cells with Co
(III) /Co(II) redox mediators have been prepared. To obtain higher conversion efficiencies, the recombination between photoinjected electrons and Co(III) species was minimized by deposition of a thin Al2 O3 blocking layer over the mesoporous TiO2 surface. Measurements of current-voltage characteristic curves, both under illumination and in dark conditions, together with electrochemical impedance spectroscopy demonstrate the great effectiveness of the addition of a blocking layer in cells containing cobalt based electrolyte, by substantially reducing the recombination current. The consequent power conversion efficiency increase is more than double, passing from 0.94% to 2.48% under 300 W m-2 AM 1.5 illumination. [ABSTRACT FROM AUTHOR]- Published
- 2009
- Full Text
- View/download PDF
26. Sensitization of TiO2 with ruthenium complexes containing boronic acid functions
- Author
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Altobello, S., Bignozzi, C.A., Caramori, S., Larramona, G., Quici, Silvio, Marzanni, Giovanni, and Lakhmiri, Rajae
- Subjects
- *
TITANIUM dioxide , *SOLAR energy , *PLATINUM group , *PHOTOVOLTAIC cells - Abstract
New ruthenium complexes based on bipyiridine and terpyridyne type ligands, containing boronic acid functions, of formulae: [Ru(bpy-Φ-B(OH)2)2(CN)2], 6, (bpy-Φ-B(OH)2 = 4-(2,2′-dipyridil)phenylboronic acid), [Ru(trpy-B(OH)2)(tb2bpy)Cl](PF6), 11, (trpy-B(OH)2 = 4-[4′-(2,2′:6′,2″-terpyridil]-boronic acid), [Ru(trpy)-Φ-B(OH)2)(tb2bpy)Cl] (PF6), 12, (trpy)-Φ-B(OH)2 = 4-[4′-(2,2′:6′,2″-terpyridil]-phenylboronic acid), have been prepared, characterized, and tested in dye-sensitized solar cells (DSSCs). The results of this first study indicate that: (i) the boronic acid function acts as interlocking group between sensitizer and mesoporous titanium dioxide; (ii) only the presence of two B(OH)2 groups/molecule allow to obtain high photoanode surface coverages with optical densities > 1; (iii) The presence of the phenyl spacer in 12 reduces the photocurrent efficiency with respect to complex 11, most probably for a reduced electronic coupling between excited sensitizer and semiconductor conduction band. The insights gained from this work suggest that better photoelectrochemical performances should be obtained with dye molecules based on bpy type ligands bearing two boronic acid functions directly bound to the aromatic ring. [Copyright &y& Elsevier]
- Published
- 2004
- Full Text
- View/download PDF
27. Indium-modified copper nanocubes for syngas production by aqueous CO2 electroreduction
- Author
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Alessandro Niorettini, Raffaello Mazzaro, Fabiola Liscio, Alessandro Kovtun, Luca Pasquini, Stefano Caramori, Serena Berardi, Niorettini A., Mazzaro R., Liscio F., Kovtun A., Pasquini L., Caramori S., and Berardi S.
- Subjects
Inorganic Chemistry ,CO2 reduction ,copper ,nanocube - Abstract
Electroreduction of carbon dioxide represents an appealing strategy to rethink a waste product as a valuable feedstock for the formation of value-added compounds. Among the metal electrodes able to catalyze such processes, copper plays a central role due to its rich chemistry. Strategies aimed at tuning Cu selectivity comprise nanostructuring and alloying/post-functionalization with heterometals. In this contribution, we report on straightforward electrochemical methods for the formation of nanostructured Cu-In interfaces. The latter were fully characterized and then used as cathodes for CO2 electroreduction in aqueous environment, leading to the selective production of syngas, whose composition varies upon changing the applied bias and indium content. In particular, gaseous mixtures compatible with the synthesis of methanol or aldehydes (i.e. respectively with 1 : 2 and 1 : 1 CO/H2 ratios) are produced at low (i.e. −0.62 V vs. RHE) applied bias with >3.5 mA cm−2 current densities (in absolute value). Even if the proposed cathodes undergo structural modifications upon prolonged exposure to CO2 reduction conditions, their catalytic activity can be restored by introducing an additional In(iii) precursor to the electrolytic solution.
- Published
- 2022
28. New examples of Ru(<scp>ii</scp>)-tetrazolato complexes as thiocyanate-free sensitizers for dye-sensitized solar cells
- Author
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Edoardo Marchini, Loris Giorgini, Mattia Averardi, Nicola Sangiorgi, Alessandra Sanson, Valentina Fiorini, Sara Muzzioli, Stefano Stagni, Roberto Argazzi, Angela Dellai, Stefano Caramori, Fiorini V., Marchini E., Averardi M., Giorgini L., Muzzioli S., Dellai A., Argazzi R., Sanson A., Sangiorgi N., Caramori S., and Stagni S.
- Subjects
chemistry.chemical_classification ,Ruthenium DSSC Tetrazoles Thiocyanate free ,EFFICIENCY ,Absorption spectroscopy ,Thiocyanate ,POTENTIALS ,Ambientale ,Time-dependent density functional theory ,PE4_15 ,Inorganic Chemistry ,CN ,Dye-sensitized solar cell ,chemistry.chemical_compound ,LIGHT ,Deprotonation ,Dicarboxylic acid ,chemistry ,ELECTRON-TRANSFER ,TIO2 ,INJECTION ,ACID ,Polymer chemistry ,Molecule ,Chelation - Abstract
A set of three new Ru(ii) polypyridyl complexes decorated with 5-aryl tetrazolato ligands (R-CN4)-, (D series, namely D1, D3 and D4), is presented herein. Whereas complex D1 represents the pyrazinyl tetrazolato analogue of a previously reported Ru(ii) complex (D2) with the general formula cis-[(dcbpy)2Ru(N^N)]+, in which dcbpy is 2,2′-bipyridine-4,4′-dicarboxylic acid and N^N is the chelating 2-pyridyl tetrazolato anion, the design of the unprecedented Ru(ii) species D3 and D4 relied upon a completely different architecture. More specifically, the molecular structure of thiocyanate-based species cis-[(dcbpy)2Ru(NCS)2], that is typically found in benchmark Ru(ii) dyes for dye sensitized solar cell (DSSCs), was modified with the replacement of two of the -NCS ligands in favour of the introduction of 5-aryl tetrazolato anions, such as the deprotonated form of 5-(4-bromophenyl)-1H-tetrazole, for complex D3 and 5-(4-cyanophenyl)-1H-tetrazole in the case of complex D4. To streamline the behavior of the D series of Ru(ii) complexes as photosensitizers for DSSCs, an in-depth analysis of the excited state properties of D1, D3 and D4 was performed through TDDFT calculations and TDAS (nanosecond transient difference absorption spectroscopy). The obtained results highlight a trend that was confirmed once D1, D3 and D4 were tested as photosensitizers for DSSC under different conditions. Along the series of the Ru(ii) complexes, the neutrally charged species D3 and D4 displayed the best photovoltaic performances. This journal is
- Published
- 2020
29. Photoelectrochemical Properties of SnO2 Photoanodes Sensitized by Cationic Perylene-Di-Imide Aggregates for Aqueous HBr Splitting
- Author
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Roberto Argazzi, Thomas Berger, Serena Berardi, Zois Syrgiannis, Elisabetta Benazzi, Maurizio Prato, Karin Rettenmaier, Stefano Caramori, Benazzi, E., Rettenmaier, K., Berger, T., Caramori, S., Berardi, S., Argazzi, R., Prato, M., and Syrgiannis, Z.
- Subjects
Aqueous solution ,Materials science ,Cationic polymerization ,Ambientale ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,chemistry ,Electrode ,Physical and Theoretical Chemistry ,perylene ,0210 nano-technology ,Mesoporous material ,Imide ,Perylene - Abstract
Perylene-sensitized mesoporous SnO2 films were used as electrodes for photoelectrochemical HBr splitting in aqueous solution. Upon AM 1.5 G illumination, a three- to fourfold increase of the saturated photocurrent was observed when decreasing the pH of the aqueous solution from pH 3 to pH 0 (j(max) = 0.0S +/- 0.01 mA cm(-2) at pH 3 and 0.17 +/- 0.02 mA cm(-2) at pH 0, respectively). A detailed spectroscopic and electrochemical analysis of the hybrid material was carried out in order to address the impact of interfacial energetics on charge separation dynamics. UV/vis spectroelectrochemical measurements showed that the energy of semiconductor states in such systems can be adjusted independently from the molecular levels by varying proton concentration. Photoelectrochemical measurements and nanosecond-microsecond transient absorption spectroscopy reveal that pH-related changes of the interfacial energetics have only a minor impact on the charge injection rate. An increase of the proton concentration improves charge collection mainly by retarding recombination, which in the case of Br- oxidation is in critical competition with perylene regeneration. Control of the back recombination appears to be a key feature in heterogeneous molecular systems tasked to drive energetically demanding redox reactions.
- Published
- 2020
30. Better Together: Ilmenite/Hematite Junctions for Photoelectrochemical Water Oxidation
- Author
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Lucia Amidani, Stefano Caramori, Serena Berardi, Jagadesh Kopula Kesavan, Federico Boscherini, Elia Marek Meloni, Luca Pasquini, Marcello Marelli, Berardi S., Kopula Kesavan J., Amidani L., Meloni E.M., Marelli M., Boscherini F., Caramori S., and Pasquini L.
- Subjects
Pseudobrookite ,Materials science ,Band gap ,Photoelectrochemistry ,Hematite ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,PE4_15 ,hematite ,photoelectrochemistry ,Transient Absorption Spectroscopy ,titanium ,EXAFS ,electron microscopy ,transient absorption spectroscopy ,electrochemical impedance spectroscopy ,heterointerface ,oxygen evolution catalyst ,General Materials Science ,Electron Microscopy ,PE5_6 ,Absorption (electromagnetic radiation) ,PE5_3 ,Photocurrent ,Titanium ,Electron energy loss spectroscopy ,Heterointerface ,Ambientale ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Dielectric spectroscopy ,Chemical engineering ,visual_art ,electrochemical impedance spectroscopy, heterointerface ,engineering ,visual_art.visual_art_medium ,0210 nano-technology ,Oxygen Evolution Catalyst ,Research Article - Abstract
Hematite (alpha-Fe2O3) is an earth-abundant indirect n-type semiconductor displaying a band gap of about 2.2 eV, useful for collecting a large fraction of visible photons, with frontier energy levels suitably aligned for carrying out the photo-electrochemical water oxidation reaction under basic conditions. The modification of hematite mesoporous thin- film photoanodes with Ti(IV), as well as their functionalization with an oxygen-evolving catalyst, leads to a 6-fold increase in photocurrent density with respect to the unmodified electrode. In order to provide a detailed understanding of this behavior, we report a study of Ti-containing phases within the mesoporous film structure. Using X-ray absorption fine structure and high-resolution transmission electron microscopy coupled with electron energy loss spectroscopy, we find that Ti(IV) ions are incorporated within ilmenite (FeTiO3) near-surface layers, thus modifying the semiconductor-electrolyte interface. To the best of our knowledge, this is the first time that an FeTiO3/-Fe2O3 composite is used in a photoelectrochemical setup for water oxidation. In fact, previous studies of Ti(IV)modified hematite photoanodes reported the formation of pseudobrookite (Fe2TiO5) at the surface. By means of transient absorption spectroscopy, transient photocurrent experiments, and electrochemical impedance spectroscopy, we show that the formation of the Fe2O3/FeTiO3 interface passivates deep traps at the surface and induces a large density of donor levels, resulting in a strong depletion field that separates electron and holes, favoring hole injection in the electrolyte. Our results provide the identification of a phase coexistence with enhanced photoelectrochemical performance, allowing for the rational design of new photoanodes with improved kinetics.
- Published
- 2020
31. Photoelectrocatalytic degradation of emerging contaminants at WO3/BiVO4 photoanodes in aqueous solution
- Author
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Carlo Alberto Bignozzi, Luca Pasquini, Federico Boscherini, Stefano Caramori, Alberto Piccioni, Francesco Passabi, Luisa Pasti, Nicola Marchetti, Jagadesh Kopula Kesavan, Lucia Amidani, Serena Berardi, Alessandra Molinari, Michele Orlandi, Vito Cristino, Nicola Bazzanella, Cristino V., Pasti L., Marchetti N., Berardi S., Bignozzi C.A., Molinari A., Passabi F., Caramori S., Amidani L., Orlandi M., Bazzanella N., Piccioni A., Kopula Kesavan J., Boscherini F., and Pasquini L.
- Subjects
Materials science ,heterojunction ,genetic structures ,water ,photocatalytic degradation ,fabrication ,02 engineering and technology ,Electrolyte ,x-ray absorption spectroscopy ,film ,010402 general chemistry ,Electrochemistry ,Photochemistry ,01 natural sciences ,bivo4 ,efficient ,photocatalysi ,Oxidizing agent ,mineralization ,Physical and Theoretical Chemistry ,Visible-light ,X-ray absorption spectroscopy ,transformation ,Aqueous solution ,Ambientale ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Photocatalysis ,Degradation (geology) ,0210 nano-technology ,Mesoporous material ,Photoelectrocatalytic WO3/BiVO4 - Abstract
WO3/BiVO4 films obtained by electrochemical deposition of BiVO4 over mesoporous WO3 were applied to the photoelectrochemical degradation of selected emerging contaminants (ketoprofen and levofloxacine) in aqueous solutions. The WO3/BiVO4 films in this work are characterized by a mesoporous morphology with a maximum photoconversion efficiency >40% extending beyond 500 nm in Na2SO4 electrolytes. Oxygen was found to be the dominant water oxidation product (ca. 90% faradaic yield) and no evidence for the photogeneration of OH radicals was obtained. Nevertheless, both 10 ppm levofloxacine and ketoprofen could be degraded at WO3/BiVO4 junctions upon a few hours of illumination under visible light. However, while levofloxacine degradation intermediates were progressively consumed by further oxidation at the WO3/BiVO4 interface, ketoprofen oxidation byproducts, being stable aromatic species, were found to be persistent in aqueous solution even after 15 hours of solar simulated illumination. This indicates that, due to the lower oxidizing power of photogenerated holes in BiVO4 and a different water oxidation mechanism, the employment of WO3/BiVO4 in photoelectrochemical environmental remediation processes is much less universal than that possible with wider band gap semiconductors such as TiO2 and WO3.
- Published
- 2019
32. Hierarchical organization of perylene bisimides and polyoxometalates for photo-assisted water oxidation
- Author
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Nicola Demitri, Nadia Marino, Erica Pizzolato, Konstantin Dirian, Giuseppina La Ganga, Zois Syrgiannis, Carlo Alberto Bignozzi, Marcella Bonchio, Dirk M. Guldi, Stefano Caramori, Maurizio Prato, Francesco Rigodanza, Giulia Alice Volpato, Heinz Amenitsch, Andrea Sartorel, Serena Berardi, Max Burian, Bonchio, M., Syrgiannis, Z., Burian, M., Marino, N., Pizzolato, E., Dirian, K., Rigodanza, F., Volpato, G. A., La Ganga, G., Demitri, N., Berardi, S., Amenitsch, H., Guldi, D. M., Caramori, S., Bignozzi, C. A., Sartorel, A., and Prato, M.
- Subjects
Photosystem II ,General Chemical Engineering ,chemistry.chemical_element ,CATALYSTS ,010402 general chemistry ,Photochemistry ,01 natural sciences ,7. Clean energy ,Catalysis ,Artificial photosynthesis ,chemistry.chemical_compound ,Nanoscience and technology ,WO3 ,polyoxometalate ,polyoxometalates ,Chemical Engineering (all) ,perylene bisimides ,photo-assisted water oxidation ,Photocatalysis ,perylene bisimide ,Chemistry ,Nanoscale materials ,010405 organic chemistry ,PHOTODRIVEN ELECTRON-TRANSPORT ,Chemistry (all) ,Oxygen evolution ,Ambientale ,General Chemistry ,ARTIFICIAL PHOTOSYNTHESIS ,0104 chemical sciences ,Ruthenium ,chemistry ,HEXAGONAL HII PHASE ,Polyoxometalate ,Quantasome ,PHOTODRIVEN ELECTRON-TRANSPORT, HEXAGONAL HII PHASE, ARTIFICIAL PHOTOSYNTHESIS, BIVO4 PHOTOANODES, CHARGE SEPARATION, CATALYSTS, WO3 ,Perylene ,BIVO4 PHOTOANODES ,CHARGE SEPARATION - Abstract
The oxygen in Earth’s atmosphere is there primarily because of water oxidation performed by photosynthetic organisms using solar light and one specialized protein complex, photosystem II (PSII). High-resolution imaging of the PSII ‘core’ complex shows the ideal co-localization of multi-chromophore light-harvesting antennas with the functional reaction centre. Man-made systems are still far from replicating the complexity of PSII, as the majority of PSII mimetics have been limited to photocatalytic dyads based on a 1:1 ratio of a light absorber, generally a Ru–polypyridine complex, with a water oxidation catalyst. Here we report the self-assembly of multi-perylene-bisimide chromophores (PBI) shaped to function by interaction with a polyoxometalate water-oxidation catalyst (Ru4POM). The resulting [PBI]5Ru4POM complex shows a robust amphiphilic structure and dynamic aggregation into large two-dimensional paracrystalline domains, a redshifted light-harvesting efficiency of >40% and favourable exciton accumulation, with a peak quantum efficiency using ‘green’ photons (λ > 500 nm). The modularity of the building blocks and the simplicity of the non-covalent chemistry offer opportunities for innovation in artificial photosynthesis. In native photosystem II (PSII), multi-chromophore antennas surround the reaction centre, capturing light and triggering the quantized (four-flashes) photo-oxidation of water to oxygen. The PSII ‘quantasome’ is the most efficient photo-electrolyser built so far. An artificial quantasome has now been developed; it is specifically designed for oxygen evolution by self-assembling light-harvesting-perylene bisimides with a ruthenium polyoxometalate water-oxidation catalyst.
- Published
- 2019
33. Influence of Porphyrinic Structure on Electron Transfer Processes at the Electrolyte/Dye/TiO2 Interface in PSSCs: a Comparison between meso Push–Pull and β-Pyrrolic Architectures
- Author
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Stefano Caramori, Francesca Tessore, Roberto Argazzi, Vanira Trifiletti, Carlo Alberto Bignozzi, Alessio Orbelli Biroli, Maddalena Pizzotti, Luisa De Marco, Roberto Giannuzzi, Gabriele Di Carlo, Di Carlo, G, Caramori, S, Trifiletti, V, Giannuzzi, R, De Marco, L, Pizzotti, M, Orbelli Biroli, A, Tessore, F, Argazzi, R, and Bignozzi, C
- Subjects
Range (particle radiation) ,Materials science ,Solar cell ,interfacial dynamics ,Electrolyte ,porphyrins ,Photochemistry ,Regeneration kinetic ,Recombination ,regeneration kinetics ,law.invention ,Porphyrin ,Electron transfer ,law ,Energy transformation ,General Materials Science ,Materials Science (all) ,Charge injection ,Push pull ,Interfacial dynamic - Abstract
Time-resolved photophysical and photoelectrochemical investigations have been carried out to compare the electron transfer dynamics of a 2-beta-substituted tetraarylporphyrinic dye (ZnB) and a 5,15-meso-disubstituted diarylporphyrinic one (ZnM) at the electrolyte/dye/TiO2 interface in PSSCs. Although the meso push-pull structural arrangement has shown, up to now, to have the best performing architecture for solar cell applications, we have obtained superior energy conversion efficiencies for ZnB (6.1%) rather than for ZnM (3.9%), by using the I-/I-3(-)-based electrolyte. To gain deeper insights about these unexpected results, we have investigated whether the intrinsic structural features of the two different porphyrinic dyes can play a key role on electron transfer processes occurring at the dye-sensitized TiO2 interface. We have found that charge injection yields into TiO2 are quite similar for both dyes and that the regeneration efficiencies by I-, are also comparable and in the range of 75-85%. Moreover, besides injection quantum yields above 80%, identical dye loading, for both ZnB and ZnM, has been evidenced by spectrophotometric measurements on transparent thin TiO2 layers after the same adsorption period. Conversely, major differences have emerged by DC and AC (electrochemical impedance spectroscopy) photoelectrochemical investigations, pointing out a slower charge recombination rate when ZnB is adsorbed on TiO2. This may result from its more sterically hindered macrocyclic core which, besides guaranteeing a decrease of pi-staking aggregation of the dye, promotes a superior shielding of the TiO2 surface against charge recombination involving oxidized species of the electrolyte.
- Published
- 2014
34. Molecular Level Factors Affecting the Efficiency of Organic Chromophores for p-Type Dye Sensitized Solar Cells
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Svitlana Karamshuk, Alessandro Abbotto, Stefano Caramori, Riccardo Ruffo, Matteo M. Salamone, Carlo Alberto Bignozzi, Norberto Manfredi, Stefano Carli, Karamshuk, S, Caramori, S, Manfredi, N, Salamone, M, Ruffo, R, Carli, S, Bignozzi, C, and Abbotto, A
- Subjects
Control and Optimization ,Dye ,Kinetics ,Energy Engineering and Power Technology ,02 engineering and technology ,010402 general chemistry ,Photochemistry ,Triphenylamine ,01 natural sciences ,dyes ,lcsh:Technology ,NO ,Donor-acceptor ,chemistry.chemical_compound ,Electrical and Electronic Engineering ,heteroaromatic ,visible absorption ,dipolar ,donor–acceptor ,triphenylamine ,branched ,Suzuki coupling ,DFT-TDDFT ,Engineering (miscellaneous) ,Photocurrent ,donor-acceptor ,Renewable Energy, Sustainability and the Environment ,lcsh:T ,Non-blocking I/O ,Computer Science (all) ,Chromophore ,021001 nanoscience & nanotechnology ,Acceptor ,0104 chemical sciences ,Dye-sensitized solar cell ,chemistry ,Absorption band ,0210 nano-technology ,Energy (miscellaneous) - Abstract
A series of mono- and di-branched donor-π-acceptor charge-separated dyes incorporating triphenylamine as a donor and either Dalton’s or benzothiadiazole group as strong acceptors was synthesized and its fundamental properties relevant to the sensitization of nanocrystalline NiO investigated. The dyes exhibited an intense visible absorption band with a strong charge transfer character favorable to NiO sensitization, shifting the electron density from the donor to the acceptor branches. Nevertheless, the computed exciton binding energy is circa twice that of a common literature standard (P1), suggesting a more difficult charge separation. When tested in p-type dye-sensitized solar cells the dyes successfully sensitized NiO electrodes, with photocurrent densities about half than that of the reference compound. Being recombination kinetics comparable, the larger photocurrent generated by P1 agrees with the superior charge separation capability originating by its smaller exciton binding energy.
- Published
- 2016
35. Modification of Nanocrystalline WO3 with a Dicationic Perylene Bisimide: Applications to Molecular Level Solar Water Splitting
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Maurizio Prato, Roberto Argazzi, Stefano Caramori, Zois Syrgiannis, Carlo Alberto Bignozzi, Vito Cristino, Federico Ronconi, Aurelio Bonasera, Ronconi, Federico, Syrgiannis, Zoi, Bonasera, Aurelio, Prato, Maurizio, Argazzi, Roberto, Caramori, Stefano, Cristino, Vito, Bignozzi, Carlo Alberto, Ronconi F., Syrgiannis Z., Bonasera A., Prato M., Argazzi R., Caramori S., Cristino V., and Bignozzi C.A.
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Models, Molecular ,Molecular Conformation ,Nanoparticle ,Imides ,Photochemistry ,Biochemistry ,Tungsten ,Catalysis ,NO ,Catalysi ,Electron Transport ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,WO3 ,ComputingMethodologies_SYMBOLICANDALGEBRAICMANIPULATION ,perylene ,Photoelectrochemical cell ,IrO2 ,Quenching (fluorescence) ,Chemistry (all) ,charge transfer ,Water ,Oxides ,General Chemistry ,Photochemical Processes ,Solar fuel ,Nanocrystalline material ,perylene, WO3, charge transfer, IrO2 ,Microsecond ,chemistry ,Water Splitting ,Sunlight ,VISIBLE-LIGHT ,ARTIFICIAL PHOTOSYNTHESIS ,PHOTOELECTROCHEMICAL CELL ,OXIDATION CATALYSTS ,ELECTRON-TRANSFER ,FABRICATION ,Nanoparticles ,Perylene bisimide ,Water splitting ,Perylene ,MathematicsofComputing_DISCRETEMATHEMATICS - Abstract
[(N,N?-Bis(2-(trimethylammonium)ethylene) perylene 3,4,9,10-tetracarboxylic acid bisimide)(PF6)2] (1) was observed to spontaneously adsorb on nanocrystalline WO3 surfaces via aggregation/hydrophobic forces. Under visible irradiation (? > 435 nm), the excited state of 1 underwent oxidative quenching by electron injection (kinj > 108 s-1) to WO3, leaving a strongly positive hole (Eox ? 1.7 V vs SCE), which allows to drive demanding photo-oxidation reactions in photoelectrochemical cells (PECs). The casting of IrO2 nanoparticles (NPs), acting as water oxidation catalysts (WOCs) on the sensitized electrodes, led to a 4-fold enhancement in photoanodic current, consistent with hole transfer from oxidized dye to IrO2 occurring on the microsecond time scale. Once the interaction of the sensitizer with suitable WOCs is optimized, 1/WO3 photoanodes may hold potentialities for the straightforward building of molecular level devices for solar fuel production.
- Published
- 2015
36. Role of Intragap States in Sensitized Sb-Doped Tin Oxide Photoanodes for Solar Fuels Production.
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Berardi S, Benazzi E, Marchini E, Cristino V, Argazzi R, Boaretto R, Gobbato T, Rigodanza F, Cerullo G, Bozzini B, Bonchio M, Prato M, Berger T, and Caramori S
- Abstract
In view of developing photoelectrosynthetic cells which are able to store solar energy in chemical bonds, water splitting is usually the reaction of choice when targeting hydrogen production. However, alternative approaches can be considered, aimed at substituting the anodic reaction of water oxidation with more commercially capitalizable oxidations. Among them, the production of bromine from bromide ions was investigated long back in the 1980s by Texas Instruments. Herein we present optimized perylene-diimide (PDI)-sensitized antimony-doped tin oxide (ATO) photoanodes enabling the photoinduced HBr splitting with >4 mA/cm
2 photocurrent densities under 0.1 W/cm2 AM1.5G illumination and 91 ± 3% faradaic efficiencies for bromine production. These remarkable results, among the best currently reported for the photoelectrochemical Br- oxidation by dye sensitized photoanodes, are strongly related to the occupancy extent of ATO's intragap (IG) states, generated upon Sb-doping, as demonstrated by comparing their performances with PDI-sensitized analogues on both undoped SnO2 - and TiO2 -passivated ATO scaffolds by means of (spectro)electrochemistry and electrochemical impedance spectroscopy. The architecture of the ATO-PDI photoanodic assembly was further modified via the introduction of a molecular iridium-based water oxidation catalyst, thus proving the versatility of the proposed hybrid interfaces as photoanodic platforms for photoinduced oxidations in PEC devices.- Published
- 2024
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37. Solvothermally Grown Oriented WO 3 Nanoflakes for the Photocatalytic Degradation of Pharmaceuticals in a Flow Reactor.
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Cescon M, Stevanin C, Ardit M, Orlandi M, Martucci A, Chenet T, Pasti L, Caramori S, and Cristino V
- Abstract
Contamination by pharmaceuticals adversely affects the quality of natural water, causing environmental and health concerns. In this study, target drugs (oxazepam, OZ, 17-α-ethinylestradiol, EE2, and drospirenone, DRO), which have been extensively detected in the effluents of WWTPs over the past decades, were selected. We report here a new photoactive system, operating under visible light, capable of degrading EE2, OZ and DRO in water. The photocatalytic system comprised glass spheres coated with nanostructured, solvothermally treated WO
3 that improves the ease of handling of the photocatalyst and allows for the implementation of a continuous flow process. The photocatalytic system based on solvothermal WO3 shows much better results in terms of photocurrent generation and photocatalyst stability with respect to state-of-the-art WO3 nanoparticles. Results herein obtained demonstrate that the proposed flow system is a promising prototype for enhanced contaminant degradation exploiting advanced oxidation processes.- Published
- 2024
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38. Electrocatalytic Poly(3,4-ethylenedioxythiophene) for Electrochemical Conversion of 5-Hydroxymethylfurfural.
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Carli S, Marchini E, Catani M, Orlandi M, Bazzanella N, Barboni D, Boaretto R, Cavazzini A, and Caramori S
- Abstract
This study investigates the utilization of the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) as a catalytic material for the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). PEDOT films doped with different counterions were electrodeposited on graphite foil. In particular, the mobile anion perchlorate and the polymeric ionomers polystyrenesulfonate, Nafion, and Aquivion were used. The electrocatalytic properties of PEDOT films were evaluated toward the TEMPO redox mediator in the absence and the presence of HMF as a substrate for oxidation reactions. The electrocatalytic HMF oxidation was confirmed to occur at PEDOT electrodes, and it was also found that the chemical nature of PEDOT counterions controls the electrocatalytic conversion of HMF by modulating the kinetics of the electrochemical generation of the oxoammonium cation TEMPO(+). Potentiostatic electrolysis experiments showed that both the reference graphite electrode and PEDOT substrates were able to convert HMF to FDCA with an 80% faradaic efficiency (FE) and a >90% yield (FDCA), but, compared to graphite, the complete conversion of HMF to FDCA required a ca. 30% shorter time when using PEDOT electrodes doped with perchlorate or Aquivion, thanks to their ability to sustain a higher current density in the initial phase of the electrolysis. In addition, while all PEDOT films were chemically stable under the electrochemical conditions herein described, only PEDOT films doped with Aquivion were also mechanically robust and stable against delamination. Thus, the new PEDOT/Aquivion composite may represent the best choice for the implementation of PEDOT-based electrodes in TEMPO-mediated electrocatalytic applications.
- Published
- 2024
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39. Designing Ionic Ir(III) Cyclometalated Complexes as Photocatalysts for Light Assisted ATRP of MMA. A Combined Experimental and Mechanistic Study.
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Vigarani G, Marchini E, Previati E, Giorgini L, Zacchini S, Argazzi R, Massi M, Fiorini V, Caramori S, and Stagni S
- Abstract
A new family of ionic Ir(III) cyclometalated complexes with general formula [Ir(CN)
2 (NN)][Br], was designed and prepared to be assessed as photocalysts for the visible light assisted ATRP polymerization of MMA. To this purpose, our design strategy involved both: i) the decoration of the cyclometalating (CN) and the ancillary (NN) ligands with various electron withdrawing and/or electron donor substituents and, ii) the use of Br- as the counter anion for these cationic Ir(III) species. After an extensive screening in which the [Ir(CN)2 (NN)][Br]-type compounds were compared to the model neutral complex fac-[Ir(ppy)3 ], the "fully" amino-substituted ion pairs abbreviated as [10][Br] and [11][Br], exhibited the best photocatalytic performances under irradiation with CFL lamps. It is worth noting that the outcomes of transient absorption spectroscopy (TAS) experiments combined with theoretical DFT calculations, enlightened the role played by the Ir(III) complexes in the mechanism of the photoATRP process, and suggested the rationalization of the different performances that were highlighted by our Ir(III) catalyst in the visible light assisted photopolymerization of MMA., (© 2024 Wiley-VCH GmbH.)- Published
- 2024
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40. Operando double-edge high-resolution X-ray absorption spectroscopy study of BiVO 4 photoanodes.
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Piccioni A, Kopula Kesavan J, Amidani L, Mazzaro R, Berardi S, Caramori S, Pasquini L, and Boscherini F
- Abstract
High energy resolution fluorescence detected X-ray absorption spectroscopy is a powerful method for probing the electronic structure of functional materials. The X-ray penetration depth and photon-in/photon-out nature of the method allow operando experiments to be performed, in particular in electrochemical cells. Here, operando high-resolution X-ray absorption measurements of a BiVO
4 photoanode are reported, simultaneously probing the local electronic states of both cations. Small but significant variations of the spectral lineshapes induced by the applied potential were observed and an explanation in terms of the occupation of electronic states at or near the band edges is proposed., (open access.)- Published
- 2024
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41. PEDOT:Nafion for Highly Efficient Supercapacitors.
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Skorupa M, Karoń K, Marchini E, Caramori S, Pluczyk-Małek S, Krukiewicz K, and Carli S
- Abstract
Supercapacitors offer notable properties as energy storage devices, providing high power density and fast charging and discharging while maintaining a long cycling lifetime. Although poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) has become a gold standard among organic electronics materials, researchers are still investigating ways to further improve its capacitive characteristics. In this work, we introduced Nafion as an alternative polymeric counterion to PSS to form highly capacitive PEDOT/Nafion; its advantageous supercapacitive properties were further improved by treatment with either dimethyl sulfoxide or ethylene glycol. Accordingly, electrochemical characterization of PEDOT/Nafion films revealed their high areal capacitance (22 mF cm
-2 at 10 mV/s) and low charge transfer resistance (∼380 Ω), together with excellent volumetric capacitance (74 F cm-3 ), Coulombic efficiency (99%), and an energy density of 23.1 ± 1.5 mWh cm-3 at a power density of 0.5 W cm-3 , resulting from a more effective ion diffusion inside the conductive film, as confirmed by the results of spectroscopic studies. A proof-of-concept symmetric supercapacitor based on PEDOT/Nafion was characterized with a specific capacitance of approximately 15.7 F g-1 and impressive long-term stability (Coulombic efficiency ∼99% and capacitance ∼98.7% after 1000 charging/discharging cycles), overperforming the device based on PEDOT/PSS.- Published
- 2024
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42. Perfluorinated Zinc Porphyrin Sensitized Photoelectrosynthetic Cells for Enhanced TEMPO-Mediated Benzyl Alcohol Oxidation.
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Di Carlo G, Albanese C, Molinari A, Carli S, Argazzi R, Minguzzi A, Tessore F, Marchini E, and Caramori S
- Abstract
This research introduces a novel series of perfluorinated Zn(II) porphyrins with positive oxidation potentials designed as sensitizers for photoelectrosynthetic cells, with a focus on promoting the oxidation of benzyl alcohol (BzOH) mediated by the 2,2,6,6-tetramethyl-1-piperidine N -oxyl (TEMPO) organocatalyst. Three dyes, CLICK-3 , CLICK-4 , and BETA-4 , are meticulously designed to explore the impact of substituents and their positions on the perfluorinated porphyrin ring in terms of redox potentials and energy level alignment when coupled with SnO
2 /TiO2 -based photoanodes and TEMPO mediator. A comprehensive analysis utilizing spectroscopy, electrochemistry, photophysics, and computational techniques of the dyes in solution and sensitized thin films unveils an enhanced charge-separation character in the 4D-π-1A type BETA-4 . Incorporating four dimethylamino donor groups at the periphery of the porphyrin ring and a BTD-accepting linker at the β-pyrrolic position equips the structure with a more efficient donor-acceptor system. This enhancement ensures improved light-harvesting capacity, resulting in a doubled incident photon-to-current conversion efficiency (IPCE% ≃30%) in the presence of LiI compared to meso -substituted dyes CLICK-3 and CLICK-4 . Sensitizing SnO2 /TiO2 thin films with BETA-4 successfully promotes the photooxidation of benzyl alcohol (BzOH) in the presence of the rapid TEMPO radical catalyst, yielding photocurrents of approximately 125 μA/cm2 in an optimized TBPy/LiClO4 /ACN electrolyte. Notably, when lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) replaces TBPy as the base for TEMPO-catalyzed BzOH oxidation, a remarkable photocurrent of around 800 μA/cm2 is achieved, marking one of the highest values reported for this photoelectrochemical reaction to date. This study underscores that the proper functionalization of perfluorinated zinc porphyrins positions these dyes as ideal candidates for sensitizing SnO2 /TiO2 in the photodriven oxidation of BzOH. It also highlights the crucial role of carefully tuning electrolyte composition based on the electronic properties of molecular sensitizers.- Published
- 2024
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- View/download PDF
43. Iron-Sensitized Solar Cells (FeSSCs).
- Author
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Pastore M, Caramori S, and Gros PC
- Abstract
ConspectusThe harvesting and conversion of solar energy have become a burning issue for our modern societies seeking to move away from the exploitation of fossil fuels. In this context, dye-sensitized solar cells (DSSCs) have proven to be trustworthy alternatives to silicon-based cells with advantages in terms of transparency and efficiency under low illumination conditions. These devices are highly dependent on the ability of the sensitizer that they contain to collect sunlight and transfer an electron to a semiconductor after excitation. Ruthenium and polypyridine complexes are benchmarks in this field as they exhibit ideal characteristics such as long-lasting metal-ligand charge transfer (MLCT) states and efficient separation between electrons and holes, limiting recombination at the dye-semiconductor interface. Despite all of these advantages, ruthenium is a noble metal, and the development of more sustainable energy devices based on earth-abundant metals is now a must. A quick glance at the periodic table reveals iron as a potential good candidate, since it belongs to the same group of ruthenium, which suggests similar electronic properties. However, striking photophysical differences exist between ruthenium(II) polypyridyl complexes and their Fe(II) analogues, the latter suffering from short-lived MLCT states resulting of their ultrafast relaxation into metal-centered (MC) states. Pyridyl-N-heterocyclic carbenes (pyridylNHC) brought a strong σ-donor character required to promote a higher ligand field splitting of the iron d orbitals. This induces destabilization of the MC states over the MLCT manifold and a consequent slowdown of the excited states deactivation providing iron(II) complexes with tens of picoseconds lifetimes, making them more promising for applications in DSSCs. This Account highlights our recent advances in the development and characterization of iron-sensitized solar cells (FeSSCs) with a focus on the design of efficient sensitizers going from homoleptic to heteroleptic complexes (bearing different anchoring groups) and the tuning of electrolyte composition. Our rational approach led to the best photocurrent and efficiency ever reported for an iron sensitized solar cell (2% PCE and 9 mA/cm
2 ) using a cosensitization process. This work clearly evidences that the solar energy conversion based on iron complex sensitization is now an opened and fruitful route.- Published
- 2024
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- View/download PDF
44. Metal Complexes for Dye-Sensitized Photoelectrochemical Cells (DSPECs).
- Author
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Marchini E, Caramori S, and Carli S
- Abstract
Since Mallouk's earliest contribution, dye-sensitized photoelectrochemical cells (DSPECs) have emerged as a promising class of photoelectrochemical devices capable of storing solar light into chemical bonds. This review primarily focuses on metal complexes outlining stabilization strategies and applications. The ubiquity and safety of water have made its splitting an extensively studied reaction; here, we present some examples from the outset to recent advancements. Additionally, alternative oxidative pathways like HX splitting and organic reactions mediated by a redox shuttle are discussed.
- Published
- 2024
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45. Antibactericidal Ir(III) and Ru(II) Complexes with Phosphine-Alkaloid Conjugate and Their Interactions with Biomolecules: A Case of N-Methylphenethylamine.
- Author
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Wojtala D, Kozieł S, Witwicki M, Niorettini A, Guz-Regner K, Bugla-Płoskońska G, Caramori S, and Komarnicka UK
- Subjects
- Humans, NAD, Cell Line, Tumor, DNA, Coordination Complexes chemistry, Alkaloids, Ruthenium chemistry, Antineoplastic Agents chemistry
- Abstract
The phosphine ligand (Ph
2 PCH2 N(CH3 )(CH2 )2 Ph, PNMPEA) obtained by the reaction of the (hydroxymethyl)diphenylphosphine with naturally occurring alkaloid N-methylphenethylamine, was used to synthesize the half-sandwich iridium(III) (Ir(η5 -Cp*)Cl2 Ph2 PCH2 N(CH3 )(CH2 )2 Ph, IrPNMPEA) and ruthenium(II) (Ru(η6 -p-cymene)Cl2 Ph2 PCH2 N(CH3 )(CH2 )2 Ph, RuPNMPEA) complexes. They were characterized using a vast array of methods, including 1D and 2D NMR, ESI(+)MS spectrometry, elemental analysis, cyclic voltammetry (CV), electron spectroscopy in the UV-Vis range (absorption, fluorescence) and density functional theory (DFT). The initial antimicrobial activity in vitro toward Gram-positive and Gram-negative bacterial strains was examined, indicating that both complexes are selective towards Gram-positive bacteria, e. g., Staphylococcus aureus, where the IrPNMPEA has been more bactericidal compared to RuPNMPEA. Additionally, the interactions of these compounds with various biomolecules, such as DNA (ctDNA, plasmid DNA, 9-ethylguanine (9-EtG), and 9-methyladenine (9-MeA)), nicotinamide adenine dinucleotide (NADH), glutathione (GSH), and ascorbic acid (Asc) were described. The results showed that both Ir(III) and Ru(II) complexes accelerate the oxidation process of NADH, GSH and Asc that appeared to occur by an electron transfer mechanism. Interestingly, only IrPNMPEA leads to the formation of various biomolecule adducts, which can explain its higher activity. Furthermore, RuPNMPEA and IrPNMPEA have been interacting with the DNA through weak noncovalent interactions., (© 2023 Wiley-VCH GmbH.)- Published
- 2023
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46. Distribution of Relaxation Times Based on Lasso Regression: A Tool for High-Resolution Analysis of IMPS Data in Photoelectrochemical Systems.
- Author
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Piccioni A, Vecchi P, Vecchi L, Grandi S, Caramori S, Mazzaro R, and Pasquini L
- Abstract
Intensity-modulated photocurrent spectroscopy (IMPS) has been largely employed in semiconductor characterization for solar energy conversion devices to probe the operando behavior with widely available facilities. However, the implementation of IMPS data analysis to complex structures, whether based on the physical rate constant model (RCM) or the assumption-free distribution of relaxation times (DRT), is generally limited to a semi-quantitative description of the charge carrier kinetics of the system. In this study, a new algorithm for the analysis of IMPS data is developed, providing unprecedented time resolution to the investigation of μs to s charge carrier dynamics in semiconductor-based systems used in photoelectrochemistry and photovoltaics. The algorithm, based on the previously developed DRT analysis, is herein modified with a Lasso regression method and available to the reader free of charge. A validation of this new algorithm is performed on a α-Fe
2 O3 photoanode for photoelectrochemical water splitting, identified as a standard platform in the field, highlighting multiple potential-dependent charge transfer paths, otherwise hidden in the conventional IMPS data analysis., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)- Published
- 2023
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47. Panchromatic light harvesting and record power conversion efficiency for carboxylic/cyanoacrylic Fe(ii) NHC co-sensitized FeSSCs.
- Author
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Reddy-Marri A, Marchini E, Cabanes VD, Argazzi R, Pastore M, Caramori S, and Gros PC
- Abstract
Fe(ii) pyridyl-NHC sensitizers bearing thienylcyanoacrylic (ThCA) anchoring groups have been designed and characterized with the aim of enhancing the metal to surface charge separation and the light harvesting window in iron-sensitized DSSCs (FeSSCs). In these new Fe(ii) dyes, the introduction of the ThCA moiety remarkably extended the spectral response and the photocurrent, in comparison with their carboxylic analogues. The co-sensitization based on a mixture of a carboxylic and a ThCA-iron complex produced a panchromatic absorption, up to 800 nm and the best photocurrent and efficiency ( J
sc : 9 mA cm-2 and PCE: 2%) ever reported for an FeSSC., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)- Published
- 2023
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48. Photoelectrochemical C-H Activation Through a Quinacridone Dye Enabling Proton-Coupled Electron Transfer.
- Author
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Yang Y, Volpato GA, Rossin E, Peruffo N, Tumbarello F, Nicoletti C, Bonetto R, Paoloni L, Umari P, Colusso E, Dell'Amico L, Berardi S, Collini E, Caramori S, Agnoli S, and Sartorel A
- Abstract
Dye-sensitized photoanodes for C-H activation in organic substrates are assembled by vacuum sublimation of a commercially available quinacridone (QNC) dye in the form of nanosized rods onto fluorine-doped tin oxide (FTO), TiO
2 , and SnO2 slides. The photoanodes display extended absorption in the visible range (450-600 nm) and ultrafast photoinduced electron injection (<1 ps, as revealed by transient absorption spectroscopy) of the QNC dye into the semiconductor. The proton-coupled electron-transfer reactivity of QNC is exploited for generating a nitrogen-based radical as its oxidized form, which is competent in C-H bond activation. The key reactivity parameter is the bond-dissociation free energy (BDFE) associated with the N⋅/N-H couple in QNC of 80.5±2.3 kcal mol-1 , which enables hydrogen atom abstraction from allylic or benzylic C-H moieties. A photoelectrochemical response is indeed observed for organic substrates characterized by C-H bonds with BDFE below the 80.5 kcal mol-1 threshold, such as γ-terpinene, xanthene, or dihydroanthracene. This work provides a rational, mechanistically oriented route to the design of dye-sensitized photoelectrodes for selective organic transformations., (© 2022 Wiley-VCH GmbH.)- Published
- 2023
- Full Text
- View/download PDF
49. A Novel Hydrothermal CdS with Enhanced Photocatalytic Activity and Photostability for Visible Light Hydrogenation of Azo Bond: Synthesis and Characterization.
- Author
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Milani M, Mazzanti M, Magnacca G, Caramori S, and Molinari A
- Abstract
A good photocatalyst maximizes the absorption of excitation light while reducing the recombination of photogenerated carriers. Among visible light responsive materials, CdS has good carrier transport capacity; however, its photostability is poor and limits its use. Here, the synthesis of a new hydrothermal CdS is reported, and post-synthesis annealing determines crystal properties and spectroscopic characteristics. The introduction of sulfur vacancies as intra band gap states is the key factor for the enhancement of photocatalytic activity. In fact, by spectroscopic and photo-electrochemical experiments, we demonstrate that sulfur vacancies act as an electron sink, favoring the charge transfer process to methyl orange. In addition, the studied hydrothermal CdS is characterized by very high stability, thus enabling a visible-light active photocatalyst that is overall recyclable, stable and more efficient than the commercial benchmark.
- Published
- 2023
- Full Text
- View/download PDF
50. Liposomal Binuclear Ir(III)-Cu(II) Coordination Compounds with Phosphino-Fluoroquinolone Conjugates for Human Prostate Carcinoma Treatment.
- Author
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Komarnicka UK, Kozieł S, Pucelik B, Barzowska A, Siczek M, Malik M, Wojtala D, Niorettini A, Kyzioł A, Sebastian V, Kopel P, Caramori S, and Bieńko A
- Subjects
- Humans, Male, Copper chemistry, Liposomes, Prostate, Ions, Crystallography, X-Ray, Carcinoma, Coordination Complexes pharmacology, Coordination Complexes chemistry
- Abstract
Novel heteronuclear Ir
III -CuII coordination compounds ([Ir(η5 -Cp*)Cl2 Pcfx-Cu(phen)](NO3 )·1.75(CH3 OH)·0.75(H2 O) ( 1 ), [Ir(η5 -Cp*)Cl2 Pnfx-Cu(phen)](NO3 )·1.75(CH3 OH)·0.75(H2 O) ( 2 ), [Ir(η5 -Cp*)Cl2 Plfx-Cu(phen)](NO3 )·1.3(H2 O)·1.95(CH3 OH) ( 3 ), [Ir(η5 -Cp*)Cl2 Psfx-Cu(phen)] ( 4 )) bearing phosphines derived from fluoroquinolones, namely, sparfloxacin (Hsfx), ciprofloxacin (Hcfx), lomefloxacin (Hlfx), and norfloxacin (Hnfx), have been synthesized and studied as possible anticancer chemotherapeutics. All compounds have been characterized by electrospray ionization mass spectrometry (ESI-MS), a number of spectroscopic methods ( i . e ., IR, fluorescence, and electron paramagnetic resonance (EPR)), cyclic voltammetry, variable-temperature magnetic susceptibility measurements, and X-ray diffractometry. The coordination geometry of IrIII in all complexes adopts a characteristic piano-stool geometry with the η5 -coordinated and three additional sites occupied by two chloride and phosphine ligands, while CuII ions in complexes 1 and 2 form a distorted square-pyramidal coordination geometry, and in complex 3 , the coordination geometry around CuII ions is a distorted octahedron. Interestingly, the crystal structure of [Ir(η5 -Cp*)Cl2 Plfx-Cu(phen)] features the one-dimensional (1D) metal-organic polymer. Liposomes loaded with redox-active and fluorescent [Ir(η5 -Cp*)Cl2 Pcfx-Cu(phen)] ( 1L ) have been prepared to increase water solubility and minimize serious systemic side effects. It has been proven, by confocal microscopy and an inductively coupled plasma mass spectrometry (ICP-MS) analysis, that the liposomal form of compound 1 can be effectively accumulated inside human lung adenocarcinoma and human prostate carcinoma cells with selective localization in nuclei. A cytometric analysis showed dominance of apoptosis over the other cell death types. Furthermore, the investigated nanoformulations induced changes in the cell cycle, leading to S phase arrest in a dose-dependent manner. Importantly, in vitro anticancer action on three-dimensional (3D) multicellular tumor spheroids has been demonstrated.- Published
- 2022
- Full Text
- View/download PDF
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