Long-range ordered high-entropy intermetallics enable stable and efficient hydrogen evolution in seawater

Long-range ordered high-entropy intermetallics (HEIs) were synthesized via a thermodynamically-driven atomic ordering strategy. The (FeCoNi)(RuPt) HEI achieves 200 mA cm^-2 at an overpotential of 56 mV and a remarkable low Tafel slope of 50.4 mV dec^-1 in alkaline seawater. In situ Raman spectroscopy reveals the presence of Co-OH, M-OH-M, and Pt-OH-Pt adsorption sites on the (FeCoNi)(RuPt) surface, which are crucial for water dissociation.