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Irradiation-responsive polysulfone film as a colorimetric UVA/UVB differentiator
Publication . Monteiro, Bernardo; Leal, João Paulo; Outis, Mani; Casimiro, Maria Helena; Pereira, Cláudia C. L.; LAQV@REQUIMTE; DQ - Departamento de Química; RSC - Royal Society of Chemistry
A wearable, small size, flexible and energy consumable free colorimetric detector of UVA radiation and UVB/UVA differentiation was created based on the peculiar stimuli-responsive behaviour of an imidazolium based ionic liquid. Semi-transparent polysulfone films are transformed into opaque and homogenous red films under UVA radiation (315-360 nm), while lower wavelength exposure (280-315 nm) induces increased emission detectable under dark light, with no colour modification of the film under visible light. Thermal analysis (TGA and DSC), spectroscopic analysis (FT-IR, 1H-NMR and UV-Vis), scanning electronic microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were conducted to elucidate confinement mechanism and irradiation effects.
Electrochemical Studies of Benzoquinone, Hydrobenzoquinone, Diphenoquinone and Hydrodiphenoquinone-Based Compounds
Publication . Leitão, Flávia; Galrito, Daniel; Branco, Luís C.; Cruz, Hugo; Branco, Paula S.; DQ - Departamento de Química; Faculdade de Ciências e Tecnologia (FCT); LAQV@REQUIMTE; John Wiley and Sons Inc.
Several quinones, diphenoquinones and respective reduced forms, hydrobenzoquinones and hydrodiphenoquinones, were synthesized, and their electrochemical properties were studied by cyclic voltammetry (CV) in non-aqueous medium to assess their upcoming applicability as organic redox mediators. Benzoquinones and diphenoquinones exhibited two reversible electron transfers (ETs) as exemplified by tetra-tert-butyldiphenoquinone, which displayed ETs at standard potential (E0) at E0 = −0.53 V and E0 = −0.92 V versus SCE (saturated calomel electrode). However, hydrobenzoquinones displayed chemically irreversible ET, whereas hydrodiphenoquinones exhibited either chemically irreversible or quasi-reversible ETs. For instance, di-tert-butylhydrobenzoquinone demonstrated two irreversible ETs at Epc = 0.31 V and Epa = 1.00 V versus SCE.
Acenaphthylene-Based Chromophores for Dye-Sensitized Solar Cells
Publication . Malta, Gabriela; Pina, João; Lima, J. Carlos; Parola, A. Jorge; Branco, Paula S.; DQ - Departamento de Química; LAQV@REQUIMTE; ACS - American Chemical Society
A set of acenaphthylene dyes with arylethynyl π-bridges was tested for dye-sensitized solar cells (DSSCs). Crucial steps for the extension of the conjugated system from the acenaphylene core involved Sonogashira coupling reactions. Phenyl, thiophene, benzotriazole, and thieno-[3,2-b]thiophene moieties were employed to extend the conjugation of the π-bridges. The systems were characterized by cyclic voltammetry and by UV-vis absorption and emission. The spectroscopic characterization showed that the last three bridges resulted in red-shifted absorption and emission spectra relative to the parent phenyl-bridged compound, in accordance with TD-DFT calculations. The phenylethynyl derivative 6a achieved a conversion efficiency of 2.51% with Voc, Jsc, and FF values of 0.365 V, 13.32 mA/cm2, and 0.52, respectively. The efficiency of this compound improved to 3.15% with the addition of CDCA (10 mM), representing the best efficiency result in this study.
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Fundação para a Ciência e a Tecnologia
Programa de financiamento
Projectos de IC&DT de Consolidação de Competências e Recursos em Investigação - 2012
Número da atribuição
RECI/BBB-BQB/0230/2012