Facile and large-scale synthesis of sulfur-doped high-entropy nano-oxides for robust oxygen revolution reaction electrocatalyst

High-entropy oxide (HEO) possesses great potential as electrocatalyst for oxygen evolution reaction (OER) due to the variable composition and electronic structure. However, the scalable synthesis of high-entropy nanomaterials with excellent activity for OER catalysis is highly crucial and challenging. Herein, a microwave-assisted solution combustion strategy is presented that can easily prepare sulfur-doped (CrMnFeCoNi)₃O₄ high-entropy oxide (HEO-Sx) on a large scale in an air atmosphere. The sulfur is leached during OER process, inducing the surface reconstruction of HEO-Sx and promoting the formation of (oxy)hydroxides with high activity; thus HEO-Sx with higher sulfur content shows superior electrocatalytic activity than the HEO without sulfur-doped. The HEO-S2 sample exhibits enhanced OER performance with a low overpotential (263 mV @10 mA/cm²) and excellent durability for 120-h in 1 M KOH. This work provides a novel strategy for large-scale preparation of high-performance high-entropy nano-oxide catalysts.