General Synthesis of Composition-Tunable High-Entropy Amorphous Oxides Toward High Efficiency Oxygen Evolution Reaction.

High-entropy materials have attracted much attention in the electrocatalysis field due to their unique structure, high chemical activity, and compositional tunability. However, the harsh and complex synthetic methods limit the application of such materials. Herein, a universal non-equilibrium liquid-phase synthesis strategy is reported to prepare high-entropy amorphous oxide nanoparticles (HEAO-NPs), and the composition of HEAO-NPs can be precisely controlled from tri- to ten-component. The non-equilibrium synthesis environment provided by an excessively strong reducing agent overcomes the difference in the reduction potentials of various metal ions, resulting in the formation of HEAO-NPs with a nearly equimolar ratio. The oxygen evolution reaction (OER) performance of HEAO-NPs is further improved by adjusting the composition and optimizing the electronic structure. The FeCoNiMnCuBO exhibits a smaller overpotential (only 259 mV at 10 mA cm) and higher stability in OER compared with commercial RuO. The amorphous high-entropy structure with an optimized concentration of iron makes the binding energy of CoNi shift to a higher direction, promotes the generation of high-valence active intermediates, and accelerates the OER kinetic process. The HEAO-NPs have promising application potential in the field of catalysis, biology, and energy storage, and this work provides a general synthesis method for composition-controllable high-entropy materials.