Microwave synthesis of high-entropy alloy catalysts on graphene oxide sheets for oxygen reduction and evolution reactions

Abstract

High-entropy alloys (HEAs) are commonly synthesized through solid-state reactions and solution-mediated techniques. In this work, HEA nanoparticles were synthesized using an ultra-efficient pulse microwave (PM) method at relatively low temperatures (∼100 °C) with superior catalytic activities. During the PM synthesis process, the precursors of the reaction activate and accelerate the reaction owing to the release of localized and excessive energy. This leads to the formation of a crystallized high-entropy alloy (HEA). Pt30Al15Mn15Co10Ni15Cu15 and Pt30Al15Mn15Co10Ni15Fe15 HEA nanoparticles were synthesized without requiring additional external heat treatments. Furthermore, the synthesized entropically stable HEA nanoparticles showed excellent dispersion behavior towards graphene oxide (GO) sheets (particle size: 4–10 nm), this enhanced dispersion resulted in improved catalytic activity and long-term durability for various processes including H2 adsorption/desorption, oxygen reduction reaction (ORR), and oxygen evolution reaction (OER). The robust design of Cu-HEA-GO catalytic nanoparticles leads to increased synergistic interactions, which play a critical role in enhancing the ORR/OER activity. We firmly believe that the framework established in this study paves the way for the development of various high-performance catalysts based on HEAs for applications in fuel cells, metal-air batteries, and other electrochemical devices.