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Novel earth‐abundant metal sulfate‐containing high entropy sulfides, FeNiCoCrXS2 (where X = Mn, Cu, Zn, or Al), are synthesized via a two‐step solvothermal method. It is shown that sulfate‐containing FeNiCoCrMnS2 exhibits superior oxygen evolution reaction (OER) activity with an exceptionally low overpotential of 199, 246, 285, and 308 mV at current densities of 10, 100, 500, and 1000 mA cm–2, respectively, and surpassing its unary‐, binary‐, ternary‐, and quaternary‐metal counterparts. The electrocatalyst yields exceptional stability after 12 000 cycles and 55 h of durability even at a high current density of 500 mA cm–2. Various in situ and ex situ analyses are used to investigate the self‐reconstruction of the sulfides during the OER for the first time. The resulting metal (oxy)hydroxide is believed to be the true active center for OER. The remaining sulfate also contributes to the catalytic activity. Density function theory calculation is in good agreement with the experimental result. The extraordinary OER performance of the high entropy sulfide brings a great opportunity for desirable catalyst design for practical applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]