Ordering-dependent hydrogen evolution and oxygen reduction electrocatalysis of high-entropy intermetallic Pt 4 FeCoCuNi.

Disordered solid-solution high-entropy alloys have attracted wide research attention as robust electrocatalysts. In comparison, ordered high-entropy intermetallic alloys have been hardly explored and the effects of the degree of chemical ordering on catalytic activity remain unknown. In this study, a series of multi-component intermetallic Pt 4 FeCoCuNi nanoparticles with tunable ordering degrees were fabricated. The transformation mechanism of multi-component nanoparticles from the disordered structure into the ordered structure was revealed at the single-particle level using aberration-corrected STEM, which agrees with macroscopic analysis by SAED and XRD. The electrocatalytic performance of Pt 4 FeCoCuNi nanoparticles correlates well with their crystal structure and electronic structure. It was found that increasing the degree of order promotes electrocatalytic performance. The highly ordered Pt 4 FeCoCuNi achieves the highest mass activities towards both acidic oxygen reduction reaction (ORR) and alkaline hydrogen evolution reaction (HER) which are 18.9-fold and 5.6-fold higher than those of commercial Pt/C, respectively. The experiment also shows that this catalyst demonstrates better long-term stability than both partially ordered and disordered Pt 4 FeCoCuNi as well as Pt/C when subject to both HER and ORR. This ordering-dependent structure-property relationship provides insight into the rational design of catalysts and stimulates the exploration of many other multi-component intermetallic alloys. This article is protected by copyright. All rights reserved.