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Rrde Studies of Glycerol Electro-Oxidation: Local pH Variation and Oscillatory Dynamics

Research output: Contribution to journalJournal article

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  • Alana Zülke
  • Paula Perroni
  • Eduardo Giangrossi Machado
  • Hamilton Varela
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<mark>Journal publication date</mark>7/07/2017
<mark>Journal</mark>ECS Transactions
Issue number11
Volume77
Number of pages8
Pages (from-to)1643-1650
Publication StatusPublished
<mark>Original language</mark>English

Abstract

Using Ptdisk-Ptring electrodes we investigated glycerol electro-oxidation in alkaline media under both conventional and oscillatory conditions. The estimation of pH variation was done by polarizing the ring electrode at 100mV vs. RHE. The local depletion of OH- (variation in hydronium concentration) during oxidative steps at the disk is seen by the cathodic currents at the ring associated with hydrogen evolution, whose equilibrium potential (Nernstian potential) is shifted due to its well-known pH dependence. Typical voltammetric experiments at 20mV.s-1 in hydrodynamic conditions reveal ΔpH of around 1 unit. Higher rotation rates yielded lower peak currents. Under oscillatory conditions the situation is rather complicated as rotation of the electrode impacts on the critical population of intermediates required to sustain oscillations. It was only possible to obtain reproducible oscillatory dynamics under stationary conditions and pH variations seem not detectable by this technique.