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San Sebastián de los Reyes, Spain

Baldovi H.G.,Polytechnic University of Valencia | Alvaro M.,Polytechnic University of Valencia | Ferrer B.,Polytechnic University of Valencia | Garcia H.,Instituto Universitario Of Tecnologia Quimica
ChemPhysChem | Year: 2016

Transient absorption spectroscopy of graphene oxide (GO) and reduced graphene oxide (rGO) suspensions provides evidence for the photochemical generation of a charge-separated state on the microsecond timescale upon laser excitation. The lifetime and quantum yield of charge separation in suspended rGO were found to be higher than for GO. This could be advantageous for optoelectronic and photocatalytic applications, where graphene-based materials act as charge (electron) carriers. The electron-transfer quenching of the rGO charge-separated state by different amines is more efficient when the amine is a better electron donor and more easily oxidized. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Ding J.,NRC Institute for Chemical Process and Environmental Technology | De Miguel M.,Instituto Universitario Of Tecnologia Quimica | Lu J.,Polytechnic University of Valencia | Tao Y.,Polytechnic University of Valencia | Garcia H.,Instituto Universitario Of Tecnologia Quimica
Journal of Physical Chemistry C | Year: 2010

While stable polymer electrochromic properties are mainly realized from the electrochemical oxidation of p-type conjugated polymers, in this paper we report that stable electrochromic properties can also be easily achieved by electrochemical reduction of n-type polymers, such as PF4Ox, an alternating copolymer of quater(9,9-dioctylfluorene) and oxadiazole. The introduction of the strong electron-accepting oxadiazole unit into the poly(9,9-dioctylfluorene) main chain promoted the stability of the polymer in the electrochemical reduction. The copolymer film displayed an excellent elecrochromic property upon electrochemical reduction, which turned the colorless film at the neutral state to rosy-red at the electron charged state with a switching time of 1.1 s. The film exhibited a high stability during the electrochromic test, having only 30% loss of the transmittance change in 500 potential square-wave cycles. Fourier transform infrared (FT-IR) study revealed that decay of the electrochromic performance of the film was associated with the formation of fluorenone and quinone defects on the fluorene unit in the copolymer chain. The laser flash photolysis test showed the monomer unit had a high potential to localize an electron and became highly vulnerable to be attacked by oxygen to form the defects. These defects would act as charge carrier traps and produced a pair of inner peaks at-1.84 and 1.03 V in the cyclic voltammetry test of the copolymer film. © 2010 American Chemical Society. Source

Baldovi H.G.,Polytechnic University of Valencia | Albarracin F.,Instituto Universitario Of Tecnologia Quimica | Alvaro M.,Polytechnic University of Valencia | Ferrer B.,Polytechnic University of Valencia | Garcia H.,Instituto Universitario Of Tecnologia Quimica
ChemPhysChem | Year: 2015

A series of (N, O)-co-doped graphenes with different N and O loadings are prepared by the pyrolysis of natural chitosan. When the percentage of dopant increases, the conduction-band potential and charge-separation quantum yield increase, whereas the charge-separation lifetime decreases. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Baldovi H.G.,Instituto Universitario Of Tecnologia Quimica | Blas-Ferrando V.M.,University Miguel Hernandez | Ortiz J.,University Miguel Hernandez | Garcia H.,Instituto Universitario Of Tecnologia Quimica | And 2 more authors.
ChemPhysChem | Year: 2016

An asymmetrically substituted zinc phthalocyanine (ZnPc) with a terminal dithiolane group is anchored to Au nanoparticles (NPs) directly or through an interposed silica matrix. Transient absorption spectroscopy shows that the quenching of the ZnPc excited state by AuNPs occurs through a photoinduced electron transfer, the efficiency of which is modulated by the presence of the insulating silica matrix. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Teruel L.,Instituto Universitario Of Tecnologia Quimica | Bouizi Y.,Instituto Universitario Of Tecnologia Quimica | Atienzar P.,Instituto Universitario Of Tecnologia Quimica | Fornes V.,Instituto Universitario Of Tecnologia Quimica | Garcia H.,Instituto Universitario Of Tecnologia Quimica
Energy and Environmental Science | Year: 2010

Hydrotalcites are layered materials whose sheets are constituted by octahedra occupied by two different metals (one divalent and the other tri- or tetravalent) and having oxide or hydroxide at the corners. The excess of positive charge of the sheets is compensated by anions located at the interlamellar space. In the present work we have synthesized two hydrotalcites containing zinc and titanium (Zn/Ti atomic ratio in the gel synthesis 6.25) that differ on the absence or presence of sodium dodecyl sulfate in the interlamellar spaces. Calcination of these hydrotalcites leads to a film of intimately dispersed mixed oxide semiconductor that was used as semiconductor for dye sensitised solar cells. Using a ruthenium polypyridyl complex as dye, two photovoltaic cells constructed by films of mixed oxides derived from hydrotalcite calcination were prepared. The highest efficiency parameters were VOC = 0.63 V, JSC = 2.18 mA cm-2, FF = 0.465, η = 0.64%. These efficiency values are not far from those obtained for an analogous photovoltaic cell prepared using P25 titania. © 2010 The Royal Society of Chemistry. Source

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