Browsing by Author "Valencia, Drochss P."
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Item From a planar electrode to a random assembly of microelectrodes: A new approach based on the electrochemical reduction of 5-bromo-1, 10-phenanthroline at gold electrodes(Electrochemistry Communications, 2014) Valencia, Drochss P.; R. de Souza, , Ana P.; Gonçales, , Vinicius R.; S. Antonio, Jadielson L.; Cordoba de Torresi, Susana I.; Bertotti, MauroA random assembly of microelectrodes (RAMs) was fabricated by electrochemical reduction of 5-bromo-1,10-phenathroline in N,N-dimethylformamide (DMF), generating the 1,10-phenanthroline radical, which was covalently grafted on gold electrodes. After several potential cycles, the gold surface was partially blocked with an insulating film of 1,10-phenanthroline and the resulting modified electrode exhibited the characteristics of a RAMs for the electrochemical reduction of the reversible probe 1,4-benzoquinone in DMF. Scanning electron microscopy and atomic force microscopy were used to examine the morphology of the electrodeposited film and to characterize the existence of micro-regions of gold not coated by the 1,10-phenanthroline film.Item High Electrocatalytic Response of a Mechanically Enhanced NbC Nanocomposite Electrode Toward Hydrogen Evolution Reaction(American Chemical Society, 2017-08-22) Coy, Emerson; Yate, Luis; Valencia, Drochss P.; Aperador, Willian; Siuzdak, Katarzyna; Torruella, Pau; Azanza, Eduardo; Estrade, Sonia; Iatsunskyi, Igor; Peiro, Francesca; Zhang, Xixiang; Tejada, Javier; Ziolo, Ronald F.Resistant and efficient electrocatalysts for hydrogen evolution reaction (HER) are desired to replace scarce and commercially expensive platinum electrodes. Thin-film electrodes of metal carbides are a promising alternative due to their reduced price and similar catalytic properties. However, most of the studied structures neglect long-lasting chemical and structural stability, focusing only on electrochemical efficiency. Herein we report on a new approach to easily deposit and control the micro/nanostructure of thin-film electrodes based on niobium carbide (NbC) and their electrocatalytic response. We will show that, by improving the mechanical properties of the NbC electrodes, microstructure and mechanical resilience can be obtained while maintaining high electrocatalytic response. We also address the influence of other parameters such as conductivity and chemical composition on the overall performance of the thin-film electrodes. Finally, we show that nanocomposite NbC electrodes are promising candidates toward HER and, furthermore, that the methodology presented here is suitable to produce other transition-metal carbides with improved catalytic and mechanical properties.