Head-entropy alloys (HEA) are known as unique materials, exhibiting high mechanical strength and structural stability at high temperatures, anti-corrosion etc. Such unique properties have attracted much attention in the field of electrocatalysis, as the reduced free energy (ΔG) of HEAs should stabilize the topmost surface microstructures and thus increase the catalyst surface durability. However, at present, no study has been made on the correlations between HEAs electrocatalytic properties and lattice stacking structures, atomic-level distributions of constituent elements in the surface vicinity. In this study, we synthesized Pt-HEA(hkl) (hkl = 111, 110, 100) model catalyst surfaces by vacuum-deposition of a "Cantor alloy" (Cr-Mn-Fe-Co-Ni), followed by Pt layers on Pt single-crystal substrates in ultra-high vacuum (<10<sup>-7</sup> Pa). Then, we evaluated ORR properties of the Pt-HEA(hkl) surfaces and discuss the correlation between the topmost surface micro-structures and electrocatalytic properties of the Pt-HEA.
This study was supported by NEDO of Japan, JSPS KAKENHI (JP21H01645).