3d–5d Orbital Hybridization in Nanoflower‐Like High‐Entropy Alloy for Highly Efficient Overall Water Splitting at High Current Density

Abstract Exploring highlyefficient electrocatalysts for overall water splitting is a challenging butnecessary task for development of green and renewable energy. Herein, PtIrFeCoNi high‐entropy alloy nanoflowers (HEA NFs) withstrong 3d‐5d orbital hybridization were fabricated to achieve highly efficientoverall water splitting at high current density. The Pt 26 Ir 7 Fe 13 Co 22 Ni 32 HEA NFs achieved a 57.52‐fold higher than commercial IrO 2 in turnoverfrequency (TOF) for oxygen evolution reaction (OER). Besides, its TOF value forhydrogen evolution reaction (HER) was 2.11‐fold higher than that of commercialPt/C. The cell voltages based on Pt 26 Ir 7 Fe 13 Co 22 Ni 32 HEA NFs for overall water splitting were only 1.594 V and 1.861 V at currentdensities of 100 mA cm −2 and 500 mA cm −2 , which weresignificantly lower than those of Pt/C