Quantifying electrochemical promotion of induced bipolar Pt particles supported on YSZ

Electrochemical promotion (EP) of CO oxidation is shown for the first time on induced bipolar Pt particles supported on yttria-stabilized zirconia (YSZ). These Pt particles are formed by sputter deposition of high-purity Pt metal followed by sintering. Conditions were chosen to stay below the percolation threshold of Pt particles. In-plane polarization of Pt particles results in a bipolar system and leads to the formation of a large number of galvanic cells partially or completely polarized. We have defined an equivalent number of active cells (ncell) which has been estimated from the oxygen evolution reaction as a function of the applied current on the two feed electrodes. The CO oxidation rate is measured under high vacuum conditions as a function of applied current. The use of isotopically labeled oxygen allows the discrimination of the faradaic process (16O from YSZ) from the non-faradaic process (18O from18O2) and to determine the faradaic efficiency (Λ) and the rate enhancement (ρ) parameters in this bipolar system. These results mark an important step in the realization of electrochemical promotion on highly dispersed catalysts.