Scandium-Doped LSM Anode for Steam Electrolysis in a Proton-Conducting Solid Oxide Electrolyzer

Perovskite La_0.8Sr_0.2MnO_3-δ has been widely used as anode for proton conducting solid oxide steam electrolyzer; however, the insufficient catalytic activity still restricts the activity for electrochemical oxidation of steam. In this work, Sc-doped anode material La_0.8Sr_0.2Mn_1-xSc_xO_3-δ (x=0, 0.02, 0.05, 0.08, 0.1) with the aim of enhancing anode performance is studied. Combined characterization using XRD, TEM, XPS, SEM and EDS confirmed the successful partial replacement of Mn by Sc in B site. The doping of Sc remarkably improves ionic conductivity while accordingly decreases the mixed conductivity due to the increase of oxygen vacancies indicated by TGA and XPS. Electrochemical measurements and ionic conductivity measurements demonstrate LSMS_0.05 has the most optimized polarization properties. With LSMS_0.05 anode, the Faradic efficiency is maximized to 80% and accordingly enhanced by 25% compared with the electrolyzer with LSM anode for high temperature steam electrolysis by exposing anode to 5%H₂O/air.