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(CrMnFeCo₂Ni)O₃ 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.

High entropy spinel oxide (HESO) nanoparticles were synthesized via a surfactant-assisted hydrothermal method and used as a novel anode material in a lithium-ion battery. The HESO consists of non-equimolar cations of Cr, Mn, Fe, Co, and Ni dispersed in two Wyckoff sites with various valence states. Due to a strong entropy-induced phase stabilization effect of the HESO, no inactive MgO structural pillars, which are exclusively present in the reported rock salt type high entropy oxides, are required to achieve high electrode cycling stability. A superior charge–discharge capacity of 1235 mA h g⁻¹, the highest among all known HEOs, is obtained with 90% capacity retention after 200 cycles. The unique HESO is also characterized by plenty of oxygen vacancies and three-dimensional Li⁺ transport pathways. Also, great high-rate performance, i.e., 500 mA h g⁻¹ @ 2000 mA g⁻¹, of the HESO electrode is demonstrated.

Herein, a new high entropy material is reported, i.e., a noble metal‐free high entropy glycerate (HEG), synthesized via a simple solvothermal process. The HEG consists of 5 different metals of Fe, Ni, Co, Cr, and Mn. The unique glycerate structure exhibits an excellent oxygen evolution reaction (OER) activity with a low overpotential of 229 and 278 mV at current densities of 10 and 100 mA cm⁻², respectively, in 1 m KOH electrolyte, outperforming its subsystems of binary‐, ternary‐, and quaternary‐metal glycerates. The HEG also shows outstanding stability and durability in the alkaline electrolyte. The result demonstrates the significance of synergistic effect that gives additional freedoms to modify the electronic structure and coordination environment. Moreover, HEG@HEG electrolyzer shows a good overall water splitting performance and durability, requiring a cell voltage of 1.63 V to achieve a current density of 10 mA cm⁻².