Empirical approach for configuring high-entropy catalysts in alkaline water electrolysis

Extraordinary properties of high-entropy materials motivate their application to catalysts for water electrolysis. However, the effect of each constituent on overall catalytic activity remains poorly understood. In this study, these effects were explored by using 30 multi-metallic (10 ternary, 10 quaternary, and 10 quinary) catalysts on alkaline water electrolysis (AWE) via an empirical approach. A simple, low-cost electrodeposition method facilitates the fast screening on the configurational entropy of mixing (Delta S-mix) and electrocatalytic activity. The correlation between the Delta S-mix and the AWE activity was investigated. Notably, the quinary catalysts with lower Delta S-mix showed higher activity than ternary and quaternary catalysts. Moreover, among the five elements, the addition of Mo and Fe showed the highest overpotential decrease in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. The Cu-Mo-Ni-Co-Fe catalyst with Delta S-mix of -1.59R exhibited bi-functional activity for HER and OER, resulting that the AWE demonstrated low overpotential of 315 mV at a current density of 10 mA/cm(2).