Electrocatalytic properties of perovskite-type La1−xSrxMnO3 obtained by a novel sol–gel route for O2 evolution in KOH solutions

Perovskite-type La1−xSrxMnO3 were synthesized at 600°C by a sol–gel route involving polyacrylic acid as precursor and investigated as electrocatalysts for the O2-evolution reaction (OER) in KOH solutions. The oxide powders were produced in the form of films on pretreated Ni-supports by an oxide-slurry painting technique. The study showed that Sr-substitution in the oxide matrix did not influence the oxide roughness significantly. The true electrocatalytic activity of the catalyst decreased with increasing Sr-substitution. The reaction order has been found to be approximately unity in OH− concentration. The Tafel slope values at low potential ranged between ∼103 and ∼116 mV decade−1. The rate of OE increased with increasing temperature following the Arrhenius law. Sr-substitution of 0.4 mol reduced the electrochemical activation energy (ΔHel#0) for OE by 12.9 kJ mol−1.