Current-assisted activation of Rh/TiO2/YSZ catalyst

Rhodium thin film catalyst supported on YSZ solid electrolyte and interfaced with a dispersed TiO2 layer (Rh/TiO2/YSZ) exhibits the particular behavior of having two distinct stable states, an inactive (oxidized) and an active (metallic) state, with respect to the partial oxidn. of methane to syngas. Close to stoichiometric gas compn. (CH4:O2=2:1) at 550 DegC, the inactive Rh/TiO2/YSZ catalyst was successfully activated by current application, either pos. or neg. The obsd. phenomenon is an example of "permanent electrochem. promotion" providing a permanent rate enhancement ratio of 11 and a CO selectivity of 45%. Activation by neg. current is explained with electrochem. redn. of surface rhodium oxide, while under pos. current application the surface rhodium oxide breaks due to weakening of the Rh-O binding strength by accumulation of backspillover oxygen at the gas exposed catalyst surface. [on SciFinder (R)]