Suchergebnisse

We report on the synthesis of thin films of ZnCo 2O 4 and ZnMn 2O 4 spinels, as well as pure Co 3O 4 and Mn 3O 4 spinels, by means of electrodeposition. Spinel thin films have been analyzed by energy dispersive spectroscopy, X-ray diffraction, and Raman spectroscopy. We show that under determined deposition conditions the initial wurtzite structure of Co- and Mn-doped ZnO develops into spinel structures when the Co and Mn concentration in the films is above the solubility limit of these ions in the typical ZnO-wurtzite structure. © 2012 Elsevier Ltd. All rights reserved. ; This work was supported by Spanish Government through MICINN grants MAT2009-14625-C03-03, MAT2010-21270-C04-04 and MALTA CSD2007-0045. Financial support by the European Commission through NanoCIS project (PIRSES-GA-2010-269279) is gratefully acknowledged. Finally, we also want to acknowledge the support of Vicerrectorado de Investigacion y Desarrollo de la Universitat Politecnica de Valencia through projects UPV2011-0914 PAID-05-11 and UPV2011-0966 PAID-06-11. ; Tortosa Jorques, MD.; Manjón Herrera, FJ.; Mollar García, MA.; Marí Soucase, B. (2012). ZnO-based spinels grown by electrodeposition. Journal of Physics and Chemistry of Solids. 73(9):1111-1115. https://doi.org/10.1016/j.jpcs.2012.04.002 ; S ; 1111 ; 1115 ; 73 ; 9

6 páginas, 10 figuras, 3 tablas. ; Superconducting thick films of Y-Ba-Cu-O have been prepared via an electrodeposition procedure of the constituent metals on metallic substrates (Cu, Ag) followed by an oxidative thermal treatment. The films were electrodeposited at a constant potential of –3.5 V (vs. Ag/AgCl) from a single electrolyte bath, which contains the nitrates of the cations in dimethyl sulfoxide. The initial state of the precursor film and the formation process of the final superconducting film have been followed by IR spectroscopy, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy. In the precursor film, yttrium and copper are present as metals while barium forms a carbonate. Dimethyl sulfoxide (DMSO) is not inert under the experimental conditions and oxidises to the sulfone. The superconducting transition temperature (Tc) of the final film was ≈92 K and the critical current density (Jc) values were ≈9 500 A cm–2 at 77 K and zero field, the highest so far obtained by electrodeposition. ; This work was financially supported by CICYT Program 32 MAT95–0809 and MAT98–0729. J.G.J. wishes to thank the Basque Government/Eusko Jaurlaritza for a postdoctoral fellowship. ; Peer reviewed

In recent years, several organic electrolytes have been reported allowing calcium metal electrodeposition. In all cases, some degree of passivation on the surface of the calcium electrode was reported. Following a recent report on borate-based passivation layer playing a crucial role for Ca plating in electrolyte solutions containing Ca(BF4)2, here we report the use of a boron-containing additive. The presence of this additive allows Ca plating and stripping using a Ca(TFSI)2 containing electrolyte, which otherwise lead to the formation of a fully Ca2+ blocking passivation layer. ; Funding from the European Union's Horizon 2020 research and innovation program H2020 is acknowledged: European Research Council (ERC-2016-STG, CAMBAT grant agreement no. 715087) and H2020-MSCA-COFUND-2016 (DOC-FAM, grant agreement no. 754397). A. Ponrouch is grateful to the Spanish Ministry for Economy, Industry and Competitiveness Severo Ochoa Programme for Centres of Excellence in R&D (CEX2019-000917-S). This work has been done in the frame of the Doctoral Degree Program in Materials Science by the Universitat Autònoma de Barcelona. Alistore-European Research Institute is gratefully acknowledged for financial support through the postdoc grant to C. Bodin. ; Peer reviewed

The influence of glycine on the iron phosphorous alloy electrodeposition was investigated by electrochemical quartz microbalance (EQMB), in-situ external reflection FTIR spectroscopy, and electrochemical impedance spectroscopy (EIS) measurements. An increase of glycine concentration leads to a decrease of the iron-phosphorous alloy electrodeposition rate and an increase of hydrogen evolution. Strong adsorption of glycine species, such as H2(gly)þ, H(gly)± or/and Fe(gly)þ, have been observed during the hydrogen evolution and the Fe-P deposition reaction. Due to the concurrent hydrogen evolution the pH attains higher values at the interface than in the electrolyte bulk (pH2.5). The formation of adsorbed Fe(gly)þ and of the chelate complex Fe(gly)2 in solution avoids the precipitation of Fe(OH)2 in the pH range between 2.5 and ca. 7 at the interface. The phosphorous content of the iron phosphorous alloy deposit increases with the glycine concentration. This is due to a lower deposition rate of iron caused by the adsorption of Fe(gly)þ, while the hypophosphite reduction rate to phosphorous increases. ; This is a post-peer-review, pre-copyedit version of an article published in Electrochim. Acta. The final authenticated version is available online at: https://doi.org/10.1016/j.electacta.2019.03.203. This study has partially received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 778357 and from European Social Fund, project No 09.3.3-LMT-K-712-08-0003 under grant agreement with the Research Council of Lithuania.

Stable ethylene glycol (EG) and propylene glycol (PG) electrolytes containing СuCl2 · 2H2O, SnCl4 · 5H2O and Trilon B have been developed, which provide electrodeposition of Cu – Sn alloy with tin content varying from 34 to 52 at. % in case of EG and from 51 to 91 at. % in case of PG electrolytes. It is found that the coatings contain phases of Cu6Sn5 и Cu10Sn3 intermetallic compounds, and metallic tin is also present in case of its highest content in the alloy. It is revealed that tin content can be simply varied by the change of current density or concentrations of tin and copper compounds in glycols. The effect of electrolyte composition, deposition conditions, a nature of a substrate on the coatings deposition rate (in the limits of 0.9‒2.9 μm ∙ h‒1), total metal current efficiency (from 40 to 95 %), the ratio of metals in the alloy (from 34 to 91 at. %), its phase composition and microstructure is determined. The conditions for the deposition of Cu – Sn alloy close to the eutectic composition have been found.

The final publication is available at Springer via http://dx.doi.org/10.1007/s10008-016-3237-0. ; Abstract CuGaSe2 and CuGaS2 polycrystalline thin film absorbers were prepared by one-step electrodeposition from an aqueous electrolyte containing CuCl2, GaCl3 and H2SeO3. The pH of the solution was adjusted to 2.3 by adding HCl and KOH. Annealing improved crystallinity of CuGaSe2 and further annealing in sulphur atmosphere was required to obtain CuGaS2 layers. The morphology, topography, chemical composition and crystal structure of the deposited thin films were analysed by scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy and X-ray diffraction, respectively. X-Ray diffraction showed that the asdeposited CuGaSe2 film exhibited poor crystallinity, but which improved dramatically when the layers were annealed in forming gas atmosphere for 40 min. Subsequent sulphurization of CuGaSe2 films was performed at 400 °C for 10 min in presence of molecular sulphur and under forming gas atmosphere. The effect of sulphurization was the conversion of CuGaSe2 into CuGaS2. The formation of CuGaS2 thin films was evidenced by the shift observed in the X-ray diffraction pattern and by the blue shift of the optical bandgap. The bandgap of CuGaSe2 was found to be 1.66 eV, while for CuGaS2 it raised up to 2.2 eV. A broad intermediate absorption band associated to Cr and centred at 1.63 eV was observed in Cr-doped CuGaS2 films. ; This work was supported by Ministerio de Economia y Competitividad (ENE2013-46624-C4-4-R) and Generalitat Valenciana (Prometeus 2014/044). One of the authors (S. Ullah) acknowledges the European Union (IDEAS-Call-3, Innovation and Design for Euro-Asian scholars) for its financial support. ; Ullah, S.; Mollar García, MA.; Marí, B. (2016). Electrodeposition of CuGaSe2 and CuGaS2 thin films for photovoltaic applications. Journal of Solid State Electrochemistry. 20(8):2251-2257. https://doi.org/10.1007/s10008-016-3237-0 ; S ; 2251 ; 2257 ; 20 ; 8 ; Calixto ME, Sebastian PJ, ...

The electrode processes occurring during the electrodeposition, electropolishing and oxidation of niobium are considered. The discharge of Nb(IV) complexes during Nb electrodeposition was studied by cyclic voltammetry. The anodic polarization curve on niobium in a mixture of acids H2SO4:HF (9:1) was obtained by chronopotentiometry method, the potential range at which the highest quality and speed of electropolishing is achieved was found. The film formation mechanism of niobium pentoxide Nb2O5 on niobium was studied by cyclic voltammetry.

AbstractElectrodeposition of copper(I) thiocyanate (CuSCN) thin films has been studied in a methanolic solution on variation of the precursor ratio to control morphological, crystallographic, and optoelectronic features of the product. While the one from a stoichiometric bath containing [Cu2+]: [SCN−] = 1:1 results in a randomly oriented crystalline β‐CuSCN, that from a Cu‐rich bath strongly orient the c‐axis perpendicular to the substrate, whereas that from SCN‐rich in parallel. The Cu‐rich film is dense and transparent, whereas the other two are hazy. All of them have an optical bandgap of about 3.6 eV as typically expected for β‐CuSCN, but their p‐type doping level varied to increase the work function from 5.31 to 5.66 eV on increasing the SCN− content, as found by photoelectron yield spectroscopy. This was caused by stabilization of Cu2+ acceptor level in the presence of excess SCN−, as also supported by an enhanced photoluminescence from the d‐d transition of Cu2+ state of such a film. Thus, electrodeposition has proven its usefulness to tailor‐tune optoelectronic properties on demand for device applications.

MoS2-x films were electrodeposited cathodically onto copper rod substrates from a solution, containing MoS42- as the common Mo and S ion precursor. The catalyst loading was varied by adjusting electrodeposition conditions – applied potential and deposition time. A typical set of HER electrocatalyst experiments (polarization, Tafel slope analysis) carried out in 0.5 M H2SO4 was applied on the deposited MoS2-x films. Analysis of surface morphology (SEM) and chemical composition (EDS) were also performed. Electrochemical impedance spectroscopy in the same acidic media was used to evaluate the catalyst-solution interface and the interfacial kinetics (by calculating double layer capacitance and charge transfer resistance), as well as characterize the hydrogen adsorption process (adsorption capacitance and resistance). A linear correlation between electrodeposition time and double layer capacitance was observed. However, the charge transfer resistance was found to decrease until it plateaued at longer deposition times. The MoS2-x film, deposited for 7200 s at -1.0 V (vs. Ag/AgCl), reached 10 mA cm-2 HER current at -0.18 V (vs. RHE), and represented the best result of this study. Electrochemical impedance spectroscopy (EIS) was further applied to evaluate the subtle changes in the MoS2-x films' semiconductor properties after HER stability tests (at -40 mA cm-2), and to estimate the number of active sites on the material. EIS, in comparison to cyclic voltammetry or roughness factor calculations, is a completely non-destructive method that can be applied to accurately assess the system under investigation. ; This is a post-peer-review, pre-copyedit version of an article published in Electrochimica Acta. The final authenticated version is available online at: https://doi.org/10.1016/j.electacta.2019.06.002. This study has partially received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 778357 and from European Social Fund, project No ...