Low-temperature synthesis of small-sized high-entropy oxides for water oxidation

High entropy materials (HEMs) are attracting significant attention due to their unique structure and unprecedented application potential in many fields. Herein, a novel low temperature strategy for preparing high entropy (Co, Cu, Fe, Mn, Ni)3O4 oxides with a single-phase, the Fdm spinel structure, is developed via solvothermal synthesis followed by annealing. This is the first time that high entropy oxides were fabricated successfully at low temperature. The as-prepared high entropy oxides possess five highly dispersed metal species, and the average particle size is approximately 5 nm, which is the smallest nanometer size of the high entropy oxides that has been reported so far. By considering their unique physical and chemical properties, the resultant high entropy oxides exhibit an excellent performance for water oxidation. Hence, this work provides a new synthetic strategy for high entropy oxides to solve the bottlenecks encountered by traditional methods and broaden their application areas.