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Temporal self-organization at the solid/liquid interface: formic acid electrooxidation on platinum

Grant number: 05/04667-3
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): March 01, 2006
Effective date (End): December 31, 2006
Field of knowledge:Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
Principal Investigator:Hamilton Brandão Varela de Albuquerque
Grantee:Raphael Nagao de Sousa
Home Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Considering its relevance as a model system in electrocatalysis, the formic acid electrooxidation reaction on platinum has been extensively studied. Besides the available literature concerning the temporal self-organization, it has been recently reported the existence of complex dynamics when the system is perturbed by the presence of small amounts of anions different from those already present in the supporting electrolyte. It was demonstrated that the impact of the presence of such anions is far more complex than just to block surface sites as generally believed; on the other hand, from the dynamic point of view, very rich oscillatory sequences has been found. However, it has to be stressed that all experiments in the oscillatory regime were carried out under galvanostatic control. Given the importance of the potentiostatic operation mode on the spatiotemporal dynamics, the goal of the present project is to study the temporal self-organization processes in the formic acid electrooxidation reaction on platinum in the presence of different anions added to the supporting electrolyte. The experiments will be performed in sulphuric and perchloric acid aqueous solutions perturbed by the presence of tetrafluoroborate, hexafluorophosphate, and trifluoromethanesulphonate anions. The key aspects of the system’s dynamics will be investigated by means of usual electrochemical techniques and also in terms of gravimetric studies with the electrochemical quartz crystal nanobalance. The experimental strategy is focused on the identification of parameter regions where stable current oscillations are observed, including the mechanistic analysis of the underlying aspects. (AU)