Synergistic multi-site and surface reconstruction in medium-entropy FeCoNiCuS homogeneous junction for efficient oxygen evolution

This FeCoNiCuS medium-entropy homogeneous junction catalyst, made via a simple hydrothermal method, offers exceptional stability and efficiency for oxygen evolution. It dynamically transforms during use into amorphous NiOOH and Fe2O3 phases, which expose highly active sites. It requires low overpotentials of just 267 and 615 mV to achieve current densities of 100 and 1000 mA cm−2, respectively. The catalyst is extremely stable, maintaining operation for over 190 h with minimal decay. In a water-splitting device, it requires low voltages of 1.466 and 2.202 V to drive the same currents. Most notably, it endures ultrahigh current densities (2 A cm−2) for over 210 h without damage.