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A scandium-doped manganate anode for a proton-conducting solid oxide steam electrolyzer

Gan, Lizhen, Ye, Lingting, Liu, Mingzhou, Tao, Shanwen, Xie, Kui
RSC advances 2015 v.6 no.1 pp. 641-647
X-ray diffraction, X-ray photoelectron spectroscopy, anodes, electrochemistry, electrolysis, energy-dispersive X-ray analysis, manganese, oxidation, scandium, scanning electron microscopy, steam, temperature, transmission electron microscopy
Perovskite La₀.₈Sr₀.₂MnO₃₋δ is widely used as an anode for proton-conducting solid oxide steam electrolyzers; however, the insufficient electro-catalytic activity still restricts the electrochemical steam oxidation activity. In this work, catalytically-active scandium is doped into the B-site of the manganate La₀.₈Sr₀.₂Mn₁₋ₓScₓO₃₋δ (x = 0–0.1) to enhance the electrocatalytic performance. Combined characterizations of XRD, TEM, XPS, SEM and EDS confirm the successful partial replacement of Mn by Sc in the B-site. The doping of Sc remarkably improves ionic conductivity while accordingly decreases electronic conductivity. The electrocatalytic activity has been greatly improved and the composition of La₀.₈Sr₀.₂Mn₁₋ₓScₓO₃₋δ with x = 0.05 has demonstrated the best electrode polarization performance. The faradic efficiency is significantly enhanced to as high as 80% for La₀.₈Sr₀.₂Mn₁₋ₓScₓO₃₋δ (x = 0.05) in a proton conducting solid oxide electrolyzer in contrast to a cell with traditional LSM anode for high temperature steam electrolysis.