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215 results on '"Oskam, G."'

12. Electrodepósito de níquel negro sobre aletas de cobre para aplicaciones en colectores solares planos

Author

García-Valladares, O., Gómez-Espinoza, V., Pérez-Espinosa, R., Lizama-Tzec, F., Vega-Poot, A., Herrera-Zamora, D., Becerril-González-Montecinos, J., Padrón-Hernández, W., Rodríguez-Gattorno, G., Ares-Muzio, O., and Oskam, G.

Subjects
Solar energy, Solar collectors, Electroplating, Selective surfaces
Abstract

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia Solar RESUMEN: En este trabajo se reporta el desempeño de colectores solares construidos con aletas de cobre recubiertas con níquel/níquel negro con y sin SiO2. Los recubrimientos de níquel y níquel negro fueron obtenidos mediante electrodepósito y la capa de SiO2 por sol-gel y roció pirolítico, los resultados se comparan con un colector construido con un recubrimiento selectivo comercial TiNOX. Los resultados muestran que el níquel negro con SiO2 tiene una curva de desempeño cercana al colector construidos con el recubrimiento comercial. El recubrimiento de níquel negro con SiO2 fue obtenido por técnicas de bajo costo lo cual pudiera ser atractivo para las empresas dedicadas a la construcción de colectores solares. ABSTRACT: This work reports the performance of solar collectors built with nickel / black nickel coated copper fins with and without SiO2. The nickel and black nickel coatings were obtained by electrodeposition, the SiO2 layer by sol-gel and spray pyrolysis methods, the results are compared with a collector built with a commercial selective coating TiNOX. The results show that black nickel with SiO2 have a near performance curve than the collector built with the commercial coating. The black nickel coating with SiO2 was obtained by low cost techniques which could be attractive for companies dedicated to the construction of solar collectors. info:eu-repo/semantics/publishedVersion

Published
2020

19. Reviews

Author

Veldhuis, Marcel, Roos, Piet, Davids, C., Dorgelo, Jaap, van Banning, P., Oskam, G., Mur, Luuc, and Parsons, J. R.

Published
1994
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20. The electrical and electrochemical properties of gold-plated InP

Author

Oskam, G., Bart, L., Vanmaekelbergh, D., and Kelly, J.J.

Subjects
Indium -- Research, Gold-plating -- Usage, Electrochemical analysis -- Observations, Physics
Abstract

The study of the electrical properties of InP/Au dry contacts and the influence of electrodeposited gold on the electrochemical properties of InP electrodes reveals that the chemical composition of an interfacial layer strongly influences the electrical characteristics. This is also revealed by the current and impedance measurements on InP/Au dry contacts. The interface states also has considerable influence on the electrical characteristics. The electrochemical properties of the gold-plated electrodes are determined by the interfacial layer and interface states.

Published
1993

34. Libri novi

Author

Butot, L. J. M., Donze, M., Oskam, G., de Groot, A. A., de Vooys, C. G. N., and Vaas, K. F.

Published
1977
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38. Mechanisms of electron transport and recombination in ZnO nanostructures for dye-sensitized solar cells

Author

González-Elipe, Agustín R., Vega-poot, A. G., Macías-Montero, M., Idígoras, Jesús, Borrás, Ana, Barranco, Ángel, Lizama-Tzec, Francisco I., Oskam, G., Anta, Juan A., González-Elipe, Agustín R., Vega-poot, A. G., Macías-Montero, M., Idígoras, Jesús, Borrás, Ana, Barranco, Ángel, Lizama-Tzec, Francisco I., Oskam, G., and Anta, Juan A.

Abstract

ZnO is an attractive material for applications in dye-sensitized solar cells and related devices. This material has excellent electron-transport properties in the bulk but its electron diffusion coefficient is much smaller in mesoporous films. In this work the electron-transport properties of two different kinds of dye-sensitized ZnO nanostructures are investigated by small-perturbation electrochemical techniques. For nanoparticulate ZnO photoanodes prepared via a wet-chemistry technique, the diffusion coefficient is found to reproduce the typical behavior predicted by the multiple-trapping and the hopping models, with an exponential increase with respect to the applied bias. In contrast, in ZnO nanostructured thin films of controlled texture and crystallinity prepared via a plasma chemical vapor deposition method, the diffusion coefficient is found to be independent of the electrochemical bias. This observation suggests a different transport mechanism not controlled by trapping and electron accumulation. In spite of the quite different transport features, the recombination kinetics, the electron-collection efficiency and the photoconversion efficiency are very similar for both kinds of photoanodes, an observation that indicates that surface properties rather than electron transport is the main efficiency-determining factor in solar cells based on ZnO nanostructured photoanodes. Two very different behaviors of the electron-transport properties are found in nanostructured ZnO-based photoanodes. Texturized samples show a voltage-independent transport time, whereas films produced from nanocrystalline powders exhibit a voltage-dependent signal, consistent with trap-limited electron diffusion.

Published
2014

44. Influence of Brookite Impurities on the Raman Spectrum of TiO2Anatase Nanocrystals

Author

Ceballos-Chuc, M. C., Ramos-Castillo, C. M., Alvarado-Gil, J. J., Oskam, G., and Rodríguez-Gattorno, G.

Abstract

Synthesis of TiO2anatase nanocrystals by hydrothermal methods often results in the formation of small quantities of brookite, which is difficult to eliminate by tuning the reaction conditions and is usually present in the final nanomaterial. The effect of this impurity on the Raman spectrum in anatase nanomaterials has not been fully explored. In this work, a study on the effect of reaction temperature on the position and line shape of the low-wavenumber Raman peak is presented. A comparison of the spectra of nanomaterials of pure anatase and anatase with brookite impurity (4–13 nm), synthesized by hydrothermal microwave heating, is made. It is shown that the low-wavenumber Raman peak (100–300 cm–1) for pure anatase nanocrystals is strongly dependent on the nanocrystal size and that the peak position is well described by the phonon confinement model (PCM). For anatase nanocrystals with 15% brookite impurity, the spectrum shows an asymmetric band, which is formed mainly by the contributions of the anatase Egand brookite A1gmodes, with the brookite B1gand B3gpeaks further broadening the band. In addition, the PCM no longer describes the peak position. These results show that even a small amount of brookite can have a strong influence on the Raman spectra of anatase/brookite-impurity samples.

Published
2018
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46. In memoriam dr. J.J. Rook

Author

Oskam, G. and Oskam, G.

Abstract

Op 23 mei 2010 overleed dr. J.J. Rook op de leeftijd van 89 jaar. Zijn naam blijft onverbrekelijk verbonden aan de ontdekking van chloroform en andere trihalomethanen in gechloord drinkwater. Hij veroorzaakte daarmee een omwenteling op het gebied van de drinkwaterzuivering.

Published
2010

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