Advanced High Entropy Perovskite Oxide Electrocatalyst for Oxygen Evolution Reaction

Abstract A new type of lanthanum‐based high entropy perovskite oxide (HEPO) electrocatalyst for the oxygen evolution reaction is reported. The B‐site lattices in the HEPO consist of five consecutive first‐row transition metals, including Cr, Mn, Fe, Co, and Ni. Equimolar and five non‐equimolar HEPO electrocatalysts are studied for their OER electrocatalytic performance. In the five non‐equimolar HEPOs, the concentration of one of the five transition metals is doubled in individual samples. The performances of all the HEPOs outperform the single perovskite oxides. The optimized La(CrMnFeCo 2 Ni)O 3 HEPO exhibits an outstanding OER overpotential of 325 mV at a current density of 10 mA cm −2 and excellent electrochemical stability after 50 h of testing.