Newswise — In 2004, high-entropy alloys (HEAs) were introduced as a class of alloys comprising multiple principal elements in almost equal proportions. These alloys possess a distinctive chemical composition that leads to a considerable level of chemical disorder or entropy. This unique characteristic gives rise to exceptional properties, including high strength, ductility, and remarkable resistance to wear and tear, even under high-temperature conditions. Over the years, researchers have invested substantial effort in creating innovative HEAs to enhance the performance of diverse electrocatalyst materials.
The intricate atomic-level surface configurations of high-entropy alloys (HEAs) result from their diverse constituent elements. Understanding this complexity is vital as surface properties play a significant role in determining the catalytic activity of materials. Consequently, researchers are actively investigating the relationship between the atomic arrangement and the catalytic properties demonstrated by HEAs.
Recently, a collaborative research team achieved a significant breakthrough by developing a novel experimental platform. This platform allows precise control over the atomic-level structure of HEAs' surfaces and facilitates the thorough examination of their catalytic properties. The remarkable achievement of this research was reported in the prestigious journal Nature Communications on July 26, 2023.
Toshimasa Wadayama, a professor at Tohoku University's Graduate School of Environmental Studies and co-author of the paper, elucidated the study's approach. They created thin layers of a Cantor alloy, comprising a combination of elements (Cr-Mn-Fe-Co-Ni), on platinum (Pt) substrates. This unique setup served as a model surface to investigate the oxygen reduction reaction (ORR) in detail.
Employing cutting-edge imaging techniques, the team meticulously analyzed the atomic-level structure of the Pt-HEAs' surfaces and thoroughly investigated their performance in the oxygen reduction reaction (ORR). Astonishingly, they observed that the Pt-HEAs' surfaces exhibited superior ORR properties when compared to surfaces composed of a platinum-cobalt alloy. This remarkable difference suggests that the atomic arrangement and element distribution near the surface create a 'pseudo-core-shell-like structure,' which plays a crucial role in the exceptional catalytic properties of Pt-HEAs.
Importantly, Wadayama and his group emphasized the broad applicability of their findings, not only concerning the constituent elements but also extending to other nanomaterials. These discoveries have the potential to influence and benefit various fields of research and applications.
"Our newly developed experimental study platform presents a potent tool to explore the intricate relationship between surface microstructures of multi-component alloys and their catalytic properties. This platform proves effective in unraveling the precise correlations among atomic-level surface microstructures and electrocatalytic properties of high-entropy alloys (HEAs) containing various constituent elements and ratios. Consequently, it can generate reliable training datasets for materials informatics. Beyond electrocatalysis, this versatile platform holds promise for applications in diverse fields of functional nanomaterials.
Looking ahead, the group envisions expanding the platform's practical applications into electrocatalysis by utilizing Pt-HEA nanoparticles. These nanoparticles aim to enhance electrochemical surface areas, thereby opening up new possibilities for improving catalytic performance."
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