Plasma-Enhancement of Oxygen Pumping: The Role of Atomic Oxygen

Sluggish surface oxygen reduction kinetics remain a principal barrier to efficient oxygen pumping in solid oxide electrochemical cells (SOECs), where dissociative adsorption of O₂ on lanthanum strontium manganite (LSM) electrodes is widely established as the rate-limiting step, particularly under reduced oxygen partial pressure and cathodic polarization conditions. While low-temperature plasmas generate reactive oxygen species, their coupling to electrochemical oxygen transport has not been quantitatively addressed. This work couples an oxygen-containing glow discharge to a symmetric LSM|YSZ|LSM SOEC to directly supply reactive oxygen species to the SOEC cathode. A 180% increase in oxygen pumping capacity is observed at 585 °C in 1 Torr He (80%)-O₂ (20%) plasma at 470 W. Open-circuit voltage (OCV) measurements reveal a shift in electrochemical equilibrium consistent with increased surface oxygen activity. A surface reaction model identifies atomic oxygen as the dominant contributor to this enhancement. These findings demonstrate plasma-electrochemical coupling as a viable route to solid oxide oxygen separation at reduced operating temperatures.