Self-supported AlFeNiCoMo high-entropy alloy with micropillar array structure for efficient oxygen evolution reaction

The development of low-cost and efficient electrocatalysts for oxygen evolution reaction (OER) is crucial for the application of hydrogen energy. In this work, a self-supported AlFeCoNiMo high entropy alloy with a uniformly distributed micropillar array structure on the surface is prepared by melt spinning followed by dealloying. The catalyst exhibits a low overpotential of 228, 265, and 318 mV to drive the current densities of 10, 100, and 1000 mA/cm2, a small Tafel slope of 51 mV/dec, and excellent long-term stability for 30 h in 1.0M KOH electrolyte for OER. The high catalytic activity is attributed to the unique micropillar array with rich active sites and the synergistic effect between multiple metallic elements. The good stability of the catalyst results from the steady micropillar array structure and the formation of oxyhydroxides on the surface during long-term catalysis. This work provides a facile and scalable method for the preparation of self-supported, low-cost, and high-performance OER electrocatalysts.