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

Author(s)

Zulke, A. ; Perroni, P. ; Machado, E. G. ; Varela, H. ; Manivannan, M ; Narayan, S ; Kostecki, R ; Johnson, C ; Atanassov, PB

• Document type: Journal article
• Source: SOLID OXIDE FUEL CELLS 10 (SOFC-X), PTS 1 AND 2; v. 77, n. 11, p. 8-pg., 2017-01-01.

Abstract

Using Pt-disk-Pt-ring 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 Off (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 Delta pH 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. (AU)

• FAPESP's process: 09/07629-6 - Electrocatalysis IV: fundamental and applied aspects of electrocatalytic processes, bio-electrocatalysis and kinetic instabilities
• Grantee: Edson Antonio Ticianelli
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Thematic Grants
• FAPESP's process: 12/21204-0 - Temporal self-organization in electro-oxidation of small organic molecules: surface structure effect, water concentration and temperature
• Grantee: Bruno Alarcon Fernandes Previdello
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 13/06205-3 - Kinetic instabilities at the electrode/solution interface: measurement and variation of the surface temperature
• Grantee: Alana Aragon Zulke
• Support Opportunities: Scholarships in Brazil - Doctorate