Outstanding OER performance under industrial conditions of porous branched high-entropy oxides prepared through anodization of FeCoNiMnTi alloy

Due to the diversity of active sites and multi-component synergies of high-entropy oxides (HEO), they have received extensive attention in the field of OER catalysis. However, there are still great challenges in exploring new preparation strategy and achieving precise morphology control of HEO. In this study, the HEO self-supported electrodes (f-MOx@f-MA) were prepared via anodization of FeCoNiMnTi alloy (f-MA). The influence of anodization parameters and annealing temperature on the morphology, structure, and OER catalytic performance were investigated in detail. Under optimal conditions (1 M KOH), a porous branch-like high-entropy oxide (f-MOx) with an amorphous structure was obtained, which exhibits an impressively low overpotential of 185 mV at 10 mA/cm² (η₁₀), accompanied by a corresponding Tafel slope of 40.3 mV/dec. The OER catalytic activity and stability of f-MOx@f-MA is much superior to benchmark IrO₂. Furthermore, under industrial conditions (50 °C, 6 M KOH, 400 mA/cm²), f-MOx@f-MA also demonstrates superior OER catalytic activity and unwavering stability. Notably, after an uninterrupted 120-hour operation under industrial conditions, the η₁₀ value of f-MOx@f-MA is only 154 mV, which is 18 mV lower than the original sample. The outstanding OER performance of f-MOx@f-MA can be ascribed to the efficient integration of the close-connected interface between in-situ grown HEO and the alloy substrate, the nanoporous branched structures, and the harmonious synergistic effects among multi-component amorphous oxides. All these factors endow the f-MOx@f-MA with enhanced OER catalytic activity and stability and its comprehensive performance surpasses most of the recently reported high-entropy oxide electrodes.