Medium-Entropy Metal Selenides Nanoparticles with Optimized Electronic Structure as High-Performance Bifunctional Electrocatalysts for Overall Water Splitting

摘要

Development of low-cost and high-efficiency electrocatalysts for overall watersplitting is of great significance in the sustainable hydrogen economy. Herein,Fe_(1.2)(CoNi)_(1.8)Sex medium-entropy metal selenides (MESes) nanoparticles areprepared via the selenylation of metal-organic frameworks (MOFs)precursors. The optimal Fe_(1.2)(CoNi)_(1.8)Se6 MESe exhibits an outstandingelectrocatalytic performance in alkaline media, offering low overpotentials of66 and 216 mV at 10 mA cm~（?2） for the hydrogen evolution reaction and oxygenevolution reaction, respectively. A full electrolysis apparatus withFe_(1.2)(CoNi)_(1.8)Se_6 MESe as both cathode and anode displays an excellentperformance, achieving 10 mA cm~（?2） at a potential of 1.55 V. Furthermore,density functional theory calculations demonstrate that the formation ofMESe enhances the surface charge density and brings the d-band centercloser to Fermi level, as compared with that of the MOF precursor. Overall,the proposed strategy of medium-entropy materials presents a low-costapproach to fabricate energy storage and conversion devices.