J. Lee et al., Spatio-temporal interfacial potential patterns during the electrocatalyzedoxidation of formic acid on Bi-modified Pt, J CHEM PHYS, 115(3), 2001, pp. 1485-1492
We report experimental observations of the spatio-temporal dynamics in the
electro-oxidation of formic acid on a Pt ring electrode modified by bismuth
adatoms. Bismuth modification significantly enhanced the current density a
nd it was found to considerably increase the existence range of oscillation
s and spatio-temporal self-organization. Hidden negative differential resis
tance and the existence of a Hopf bifurcation were deduced from the electro
chemical impedance spectra and the occurrence of galvanostatic oscillations
. The pattern formation resulted from hybrid effects of the nonlinear chemi
stry during formic acid oxidation and the long-range coupling of the interf
acial potential induced by the chosen geometry (ring type) of the working e
lectrode. Reversible transitions between traveling pulses and oscillating s
tanding waves were observed when the outer potential or the formic acid con
centration near the electrode were used as control parameters. Experimental
results were compared with computer simulations of a reaction-migration sy
stem. The role of electrode inhomogeneities in pattern formation and the tr
ansform between patterns were discussed. (C) 2001 American Institute of Phy
sics.