Modulation of oscillatory CO oxidation on platinum using electrochemical promotion of catalysis

L. LIZARRAGA; M. GUTH; A. BILLARD; P. VERNOUX

Salamanca

Congreso; EUROPACAT IX Congress; 2009

Electrochemical promotion of catalysis (EPOC) or Non-faradaic Electrochemical Modification of Catalytic Activity (NEMCA) is based on the backspillover of ionic promoters from a solid electrolyte toward the catalyst surface upon the effect of electrical polarizations in an electrochemical cell. EPOC can be achieved by using electrochemical catalysts composed of a thin and porous film of an electronically conducting catalyst deposited on a dense solid electrolyte membrane. Significant promotional effects of catalytic performances are exposed in the literature by applying small electrical potentials (e.g. +/-2 V) or currents (e.g. +/- 100 μA) between the active metallic catalyst film and a counter electrode (catalytically inert). This study reports utilization of thin sputtered films of Pt on yttria-stabilized zirconia (YSZ), an O2- ionic conductor. Physical vapour deposition allows to minimize the noble metal loading and to increase the metallic dispersion [1]. This study describes electrochemical promotion of CO oxidation on nanometric sputtered Pt films interfaced with YSZ. Oscillations in CO oxidation reaction rate have been observed over a wide range of pressures from 10-6 mbar to 1 bar [2]. Those under high pressure have been described by the oxide model[3]. The latter assumes that part of the active surface is covered by chemisorbed oxygen which is transformed into an inactive state as oxide, strongly adsorbed on Pt. In this present study, EPOC was used in order to modify the Pt catalytic surface by pumping O2- ions from or to it [4]. It was possible to start or stop the oscillatory oxidation of CO when small electrical currents were applied.