Current efficiency of electrochemical hydrogen pumping using a high-temperature proton conductor SrCe0.95Yb0.05O3-alpha

Current efficiency of electrochemical hydrogen pumping from wet hydrogen ga s through a SrCe0.95Yb0.05O3-alpha proton-conducting solid electrolyte was investigated at 900 degrees C, A decrease in current efficiency was observe d at relatively high current density, The critical current density for the reduction of the efficiency decreased with increasing amount of water vapor in the anode hydrogen gas. Addition of a small amount of argon to the anod e gas had no effect on the pumping characteristics. It was concluded that t he lack of hydrogen and the increase in partial pressure of oxygen at the a node on sending high current could cause the partial hole conduction in the electrolyte and the decrease in current efficiency of the hydrogen pump. ( C) 2000 Elsevier Science B.V. All rights reserved.