Electrocatalytic Behavior of Perovskite-related Cobaltites and Nickelates in Alkaline MediA

摘要

Dense ceramic anodes of perovskite-type La_(1-x-y)Sr_xCo_(1-z)Al_zO_(3-δ)( x = 0.45-0.70; y = 0-0.05; z = 0-0.20) and K_2NiF_4-type La_2Ni_(1-x)Me_xO_(4+δ) (Me = Co, Cu; x = 0-0.20), synthesized by the glycine-nitrate technique, were assessed for oxygen evolution in alkaline media. The lowest overpotentials are observed for (La_(0.3)Sr_(0.7))_(0.97)CoO_(3-δ), which exhibits a significant oxygen deficiency in combination with high conductivity associated with the A-site cation nonstoichiometry compensation mechanism via Co~(4+) formation. Perovskite-type cobaltite anodes are essentially stable in alkaline solutions, whilst La_2NiO_4-based electrodes exhibit degradation at the potentials where the oxygen evolution occurs, probably due to the electrochemical oxygen intercalation in the lattice.