Electrochemical properties of lanthanum nickel oxide

Electrochemical properties of lanthanum nickel oxide, LaNiO₂₈₄, were studied in alkaline solutions. It was concluded that redox reactions of Ni⁴⁺/Ni³⁺ and Ni³⁺/Ni²⁺ in a solid surface layer took place at 0.4 V and ?0.4 V (vs. Hg/HgO), respectively. As the conductivity of the oxide is a function of the oxygen concentration due to σ^* bond formation, the resistivity of the electrode was changed depending on polarization potentials. The catalytic activity for oxygen reduction of a preoxidized electrode seemed to be higher than that of an electrode not intentionally oxidized, and the activity depended on the concentration of the alkaline solution. It was presumed that Ni³⁺ cations which form the σ^* bond with oxygen have an important role in the electrocatalysis of oxygen reduction on lanthanum nickel oxide.