New high-entropy transition-metal sulfide nanoparticles for electrochemical oxygen evolution reaction

Developing extremely efficient electrocatalysts for oxygen evolution reactions (OER) is a decisive step toward the progression of rechargeable metal-oxygen batteries, CO2 reduction, and water-splitting. Nanoporous high-entropy transition-metal sulfides (np-HETMS) represent a new generation of promising OER catalysts by virtue of their exceptional catalytic activity. However, their synthesis maintains to be a challenge by reason of the thermodynamic immiscibility of the constituting multi-principal metallic elements in the sulfide structure. Herein, for the first time, the np-HETMS ((CoFeNiMnCu)S2) nanoparticles with pyrite-phase was synthesized via a facile and easy adaptable glycerol-assisted self-template approach to resolve the immiscibility of multi-metallic constituents. The coordination of metal ions with polyalcohol in metal glycerate, as an intermediate template, is beneficial for achieving atomic blending of multiple metal ions in sulfides structure at HETMSs during the synthesis procedure. In reliance on the electronic and physicochemical traits, the electronic configuration of as-synthesized (CoFeNiMnCu)S2 was elucidated by virtue of the comparison with its quaternary, ternary, and binary subsystems. The superior performance of np-HETMS (CoFeNiMnCu)S2 nanoparticles, corresponding subsystems, and commercial RuO2 catalyst are accentuated by integrating into a three-electrode configuration for OER reaction. The (CoFeNiMnCu)S2 nanoparticles exhibited a trivial overpotential of 284 mV when the current density reached 10 mA/cm2 with a low Tafel slope of 57 mV/dec in a 1.0 M KOH solution. Besides providing a novel and highly active high-entropy-based electrocatalyst, this work inaugurates a new synthesis paradigm toward high-entropy metal alloys for extremely efficient electrocatalysis applications.