Synthesis of (La,Sr)CoO3 perovskite films via a sol-gel route and their physicochemical and electrochemical surface characterization for anode application in alkaline water electrolysis

Physicochemical and electrocatalytic properties of perovskite-type La1-xSrxCoO3 (x = 0, 0.1, 0.2, 0.3, 0.5) synthesized by a low-temperature sol-gel process have been studied. Films were p-type semiconducting with a flat-band potential of approximately 0.30 V (Hg/HgO/1 mol dm(-3) KOH). The cyclic voltammogram between 0 and 0.65 V exhibited a pair of redox peaks (E(0) = 0.43 V) prior to the onset of O-2 evolution at the oxide film in 1 mol dm(-3) KOH. Among the oxide catalysts prepared, La0.7Sr0.3CoO3 was the most active electrocatalytically. The Tafel slope and the reaction order for electrolytic evolution of oxygen were found to be 65-72 mV decade(-1) and ca. 1, respectively. Strontium substitution for La in the mixed-oxide lattice enhanced the electrochemically active area; the effect being greatest with 0.3 mol strontium.