High-entropy FeCoNiMn (oxy)hydroxide as high-performance electrocatalyst for OER and boosting clean carrier production under quasi-industrial condition

Hydrogen is recognized as the most promising sustainable energy carrier. It is important to boost oxygen evolution reaction (OER) to produce more hydrogen. High-entropy compounds are a potential category of electrocatalysts for water splitting due to their outstanding reactivity and stability. Noble metal-free high-entropy FeCoNiMn (oxy)hydroxide was synthesized over a large area of 100 cm² on nickel foam using a facile approach of one-step electrodeposition. High-entropy FeCoNiMnOOH led to outstanding OER activity with a low overpotential of 282 mV at current density of 100 mA cm⁻² and showed excellent performance at room temperature as determined by the stability test for over 200 h at a high current density of 500 mA cm⁻² in 1.0 M KOH. Under quasi-industrial condition of using 6.0 M KOH solution at 333 K, only 1.64 V was required to reach a high current density of 3000 mA cm⁻². In addition, the high-entropy catalyst maintained its stability at a high current density of 1000 mA cm⁻² for over 40 h, suggesting its suitability for practical application.