Synergistic modulation of Li-doped FeCoNiMnZn HEO and modified nickel foam substrate for efficient OER electrocatalysis

Developing high-performance non-noble metal electrocatalysts is critical for efficient oxygen evolution reaction (OER) in water electrolysis. High-entropy oxides (HEOs) have attracted extensive attention owing to their multi-element synergy and structural stability, but their practical applications are limited by high interfacial resistance and insufficient intrinsic activity. In this work, Li-doped FeCoNiMnZn HEOs were synthesized via a sol-gel combustion method and loaded onto bare nickel foam (NF) and ONF. The effects of Li doping and substrate modification on crystal structure, electronic state, and OER performance were systematically investigated. Results show that 7.5% Li doping optimizes the electronic structure and modulates oxygen vacancy defects, while the ONF substrate greatly reduces interfacial charge-transfer resistance. The optimal ONF-7.5% catalyst exhibits a low overpotential of 240 mV at 10 mA·cm −2 , a small Tafel slope of 54.84 mV·dec −1 , and excellent long-term stability for 100 h. This work provides a feasible strategy of combining Li doping and substrate interfacial engineering to boost OER performance of HEOs.