IrPdCuFeNiCoMo Based Core‐Shell Icosahedron Nanocrystals and Nanocages for Efficient and Robust Acidic Oxygen Evolution

Abstract Facets engineering of high entropy alloy (HEA) nanocrystals might be achieved via shape‐controlled synthesis, which is promising but remains challenging in designing Ir‐based catalysts towards efficient and robust oxygen evolution reaction (OER) in acidic medium. Herein, icosahedra nanocrystals featured with PdCu core and IrPdCuFeNiCoMo shell were prepared by wet‐chemical reduction in one‐pot, ascribing to the initial formation PdCu core and subsequent deposition and diffusion of IrPdCuFeNiCoMo HEA shell. Sequential selective chemical etching of PdCu core results in IrPdCuFeNiCoMo HEA nanocages, delivering an overpotential of 235 mV at 10 mA cm −2 , 51.0 mV dec −1 , and 1624 A g Ir −1 at 1.50 V vs reversible hydrogen electrode in a conventional three electrode cell. In a proton exchange membrane water electrolyzer, it delivers a low cell voltage of 1.65 and 1.77 V at a current density of 1.0 and 2.0 A cm −2 , respectively, and maintains stable over 900 h at 500 mA cm −2 . Theoretical calculations attribute the enhanced intrinsic activity to the broad distribution of the binding energy for OER intermediates on IrPdCuFeNiCoMo HEA, which breaks the linear scaling relationship and accelerates the OER process.