Bistabilidade induzida pela presença da 1,10-fenantrolina na eletrodeposição de cobre

Author(s)

Maria Rodrigues Pinto

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Química
• Defense date: 2019-07-11

Examining board members

Raphael Nagao de Sousa; Juliano Alves Bonacin; Ernesto Chaves Pereira de Souza

• Advisor: Raphael Nagao de Sousa

Abstract

The inhibiting effect in the electrodeposition of copper resulted from the adsorption of 1,10-phenanthroline (phen), an N-heterocyclic organic molecule, on metallic copper surface due to strong interactions between the nitrogen atoms and the substrate is studied in detail. Even small additions of phen in the reaction media alters significantly the faradaic rate. We have found that the inhibition induced by phen during the electrodeposition of copper originated a dynamic instability known as bistability in a wide range of studied parameters. The instability was classified and validated by Electrochemical Impedance Spectroscopy analysis. Under the molecular perspective, the apparent molar mass of the adsorbents in the bistability domain was calculated using Electrochemical Quartz Crystal Nanobalance monitoring in the electrochemical experiments and the results indicate that mass changes occur mainly due to the reduction of copper from bivalent ions dissolved in the reaction media. Importantly, the adsorption of protonated phen molecules does not show a considerable contribution in mass variations but prevents the formation of a copper course grained morphology over the surface. Scanning Electron Microscope images indicates finer nodulations at the lower branch compared to the upper branch in the bistability domain. On the basis of these observations, a kinetic mechanism is proposed, and a good agreement is obtained between the apparent molar mass extracted from experiments and the theoretical values. Altogether, our results contribute to a detailed physical chemical description of the nonlinear behavior, bringing new insights about this reaction and pointing out the possibility to design switchable surface electrodes by taking advantage of the bistable behavior (AU)

• FAPESP's process: 17/05592-4 - Spatial-temporal resolution of surface metallic oxides on electrochemical oscillators
• Grantee: Maria Rodrigues Pinto
• Support Opportunities: Scholarships in Brazil - Master