High-Entropy Metal Sulfide Nanoparticles Promise High-Performance Oxygen Evolution Reaction

Transition metal sulfides with a multi-elemental nature represent a class of promising catalysts for oxygen evolution reaction (OER) owing to their good catalytic activity. However, their synthesis remains a challenge due to the thermodynamic immiscibility of the constituent multimetallic elements in a sulfide structure. Herein, for the first time the synthesis of high-entropy metal sulfide (HEMS, i.e., (CrMnFeCoNi)S-x) solid solution nanoparticles is reported. Computational and X-ray photoelectron spectroscopy analysis suggest that the (CrMnFeCoNi)S-x exhibits a synergistic effect among metal atoms that leads to desired electronic states to enhance OER activity. The (CrMnFeCoNi)S-x nanoparticles show one of the best activities (low overpotential 295 mV at 100 mA cm(-2) in 1 m KOH solution) and good durability (only slight polarization after 10 h by chronopotentiometry) compared with their unary, binary, ternary, and quaternary sulfide counterparts. This work opens up a new synthesis paradigm for high-entropy compound nanoparticles for highly efficient electrocatalysis applications.