Oscillatory behavior in the electrochemical oxidation of formic acid on Pt(100): rotation and temperature effects

We investigated the oscillatory behavior in the kinetics of formic acid ele ctrooxidation on Pt(100) in 1 mM HClO4 solution. We studied the effect of d ifferent experimental parameters on the oscillatory behavior, viz. defined HCOOH mass-transport to the electrode surface by using the rotating disk el ectrode technique, the temperature of the supporting electrolyte, and the n ature of anions. We suggest that the interdependence of the reaction steps during HCOOH oxidation, the adsorption of anions and the competition for ad sorption sites among the reaction partners and intermediates lead to comple x non-linear kinetics. It was evident that once the individual reactions in the dual path mechanism reach steady state the oscillations vanish. These conditions can be reached either by enhanced formic acid reaction rates ind uced by electrode rotation or by increased temperature. Under specific cond itions of anion and formic acid concentration, relaxational oscillations ca n be transformed into mixed-mode oscillations. (C) 2001 Elsevier Science B. V. All rights reserved.