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

High-entropy materials have attracted much attention due to their unique structure, chemical complexity and compositional tunability, which can achieve catalytic performance beyond that of single-component materials. However, the harsh and complex synthetic methods limit the application of such materials. Here, a universal non-equilibrium liquid-phase synthesis strategy is reported to prepare high-entropy amorphous oxide nanoparticles (HEAO-NPs), and the composition of the synthesized samples can be precisely controlled from tri- to ten-component. The non-equilibrium synthesis environment provided by an excessive strong reducing agent in the reaction system overcomes the difference in the reduction potentials of various metal ions, resulting in the formation of high-entropy amorphous oxide nanoparticles with nearly equimolar ratio. By adjusting the content of iron in Fex(Co1/2Ni1/2)80-xMn10Cu10BOx, the OER performance is further improved by optimization of the electronic structure. Compared with commercial RuO2, the Fe16Co32Ni32Mn10Cu10BOx exhibits smaller overpotential (only 259 mV at 10 mA cm-2) and higher stability (55 h i-t test and 31000 CV cycles) in OER. The excellent OER performance is attributed to the following factors: the amorphous nanostructure with a rough surface favors the OER process; the low iron content makes the binding energy of CoNi shifts to a higher direction, which promotes the generation of high-valence active intermediates and accelerates the kinetic process. The HEAO-NPs obtained in this work have promising application potential in the field of catalysis, biology, and energy storage, and it provides a general synthesis method for the composition-controllable high-entropy materials.