1 min synthesis of phase pure nanocrystalline high‐entropy sulfides for efficient water electrolysis

Abstract The development of noble‐metal free electrocatalysts with low production cost is of utmost importance for sustainable water electrolysis. Herein, we present a fast flexible synthesis pathway for the preparation of a variety of different medium‐ and high‐entropy spinel sulfides of various compositions, using a non‐aqueous microwave‐assisted synthesis without any H 2 S. Nanoparticulate high‐entropy sulfides containing up to 8 different metal cations can be obtained after an extremely short synthesis time of only 1 min and comparatively low temperatures of 200–230°C. We further demonstrate the high activity of the obtained sulfides for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER).