High‐Entropy Rare‐Earth‐Doped Pt Alloy Concave Nanocubes with High‐Index Facets for Hydrazine Oxidation Electrocatalysis

Abstract High‐entropy doping of multicomponent alloy nanocrystals enclosed by high‐index facets (HIFs) is a great challenge due to the high surface energy from HIFs and their distinct standard reduction potential and atom sizes between different metals. Herein, a novel non‐aqueous system, choline chloride‐urea‐based deep eutectic solvent, is proposed as a versatile medium to design a high‐entropy rare‐earth‐doped Pt alloy PtYLaNdSmEuGdTbDyHoEr (HERED‐Pt) concave nanocube with HIFs by the electrochemical method. Thanks to the high‐index faceted characteristics and the high‐entropy rare‐earth‐doped elemental synergy, the as‐synthesized HERED‐Pt concave nanocubes exhibit remarkable electrocatalytic performance for hydrazine oxidation reaction (HzOR) with high current density (170.58 mA cm⁻²) and low on‐set potential of 369.2 mV, which is superior than the quinary rare‐earth‐doped Pt alloy PtNdSmGdTbDy (QRED‐Pt), single rare‐earth‐doped Pt alloys (PtY, PtLa, PtNd, PtSm, PtEu, PtGd, PtTb, PtDy, PtHo, PtEr), monometallic Pt concave nanocubes and commercial Pt/C catalyst, representing a state‐of‐the‐art electrocatalyst for HzOR. Density functional theory (DFT) calculations reveal that the HERED‐Pt(510) stepped plane can effectively reduce the energy barrier and exhibits higher electrocatalytic performance than that of QRED‐Pt(510), single rare‐earth‐doped PtTb(510), and monometallic Pt(510) stepped planes for HzOR. This study provides a feasible high‐entropy doping strategy to effectively achieve a highly efficient electrocatalyst for HzOR.