Jorge T. Matsushima

Influência do eletrólito na eletrodeposição de nanopartículas de Cu sobre eletrodo de diamante dopado com boro

This paper presents the electrolyte influence on deposition and dissolution processes of Cu nanoparticles on boron doped diamond electrodes (BDD). Morphological, structural and electrochemical analysis showed BDD films with good reproducibility, quality and reversible in a specific redox system. Electrodeposition of Cu nanoparticles on DDB electrodes in three different solutions was influenced by pH and ionic strength of the electrolytic medium. Analyzing the process as function of the scan rate, it was verified a better efficiency in 0,5 mol L-1 Na2SO4 solution. Under the influence of the pH and ionic strength, Cu nanoparticles on DDB may be obtained with different morphologies and it was important for defining the desired properties.

Electrodeposition of Te and Cu Thin Films on Boron Doped Diamond (BDD) Electrode

This study was motivated by the relevance of Cu-Te system applications such as, highly efficient solar cells, photo-diode devices and various hetero-junction electronic components where they are used as p-type semiconductors [1]. Copper tellurides also exhibit technological interest due to their potential application in thermoelectric devices [2]. However, these compounds have rarely been the subject of study, and have been prepared only through dry methods, such as, sputtering and chemical vapor deposition. In this work the electrodeposition method was used to obtain the Cu, Te and Cu-Te thin films. The advantages of electrodeposition include the fact that most compound semiconductor is obtained at or near room temperature, which is considered low temperature deposition. Electrodeposition also promotes controlled growth and it is generally a low cost methodology when compared to the dry methods. Besides, BDD electrodes have received great attention due to its unique characteristics such as, inert surface with low adsorption properties, remarkable corrosion stability (even in strong acidic media), and wide working potential window in aqueous and non-aqueous electrolytes. In this way, the aim of this work is to study the electrodeposition process of Te, Cu, as well as Cu–Te system on BDD electrodes. The electrolytes were prepared with HClO4, CuSO4, TeO2 and water purified by reverse osmosis. Prior to the experiments, the solutions were dearated with N2 for 10 min. BDD films were grown on Si substrate by chemical vapor deposition (CVD) in a hot filament reactor during 6 hours. It was utilized a gaseous mixture of 99% vol. H2 and 1% vol. CH4 with a pressure of 50 torr. The boron doping was obtained from H2 forced to pass through a bubbler containing B2O3 dissolved in CH3OH. The H2 and B2O3/CH3OH/H2 were controlled in order to obtain the desired B/C ratio in CH3OH. From the Mott Schottky plot, the doping level was estimated to approximately 10 boron atoms.cm [3]. BDD films were used as working electrode. A platinum wire serves as a counter electrode and Ag/AgCl electrode was used as reference. The cyclic voltammetric experiments were performed using a potentiostat/galvanostat Autolab PGSTAT 302.

Investigation of a Cu/Pd Bimetallic System Electrodeposited on Boron-Doped Diamond Films for Application in Electrocatalytic Reduction of Nitrate

The Cu/Pd bimetallic system electrodeposited on boron-doped diamond (BDD) films for application, as electrode material in the electrochemical reduction of nitrate was studied. The electrochemical behavior of Cu, Pd, and Cu/Pd bimetallic system was evaluated by cyclic voltammetry. From these results, the formation of the Cu/Pd composite was verified. In addition, Cu with different phases and a Cu/Pd phase in the composite were obtained. Morphological analysis by scanning electron microscopy (SEM) revealed a homogeneous distribution of Cu/Pd bimetallic particles with intermediary dimensions compared to those observed in Cu or Pd electrodeposits separately. These composites were tested as electrocatalysts for nitrate reduction in Britton-Robinson buffer solution (pH 9). Electrochemical measurements showed that composites with higher Cu content displayed the best electrocatalytic activity for nitrate reduction, and the Cu/Pd phase in the bimetallic system served to improve the Cu adherence on BDD electrode.