Experimental study platform for electrocatalysis of atomic-level controlled high-entropy alloy surfaces.

High-entropy alloys (HEAs) have attracted considerable attention to improve performance of various electrocatalyst materials. A comprehensive understanding of the relationship between surface atomic-level structures and catalytic properties is essential to boost the development of novel catalysts. In this study, we propose an experimental study platform that enables the vacuum synthesis of atomic-level-controlled single-crystal high-entropy alloy surfaces and evaluates their catalytic properties.

Enhanced electrochemical hydrogen oxidation reaction and suppressed hydrogen peroxide generation properties on Pt/Ir(111) bimetallic surfaces.

Simultaneous accomplishment of high hydrogen oxidation reaction (HOR) activity and suppressed hydrogen peroxide (HO) generation is desired for anode catalysts of polymer electrolyte fuel cells. 0.3 monolayer-thick-Pt-deposited Ir(111) showed three-fold higher HOR activity than Pt(111) and suppressed HO generation under the detection limit, providing insights for effective catalyst development.

Hydrogen peroxide generation and hydrogen oxidation reactions of vacuum-prepared Ru/Ir(111) bimetallic surfaces.

From the viewpoint of the application of Ir-Ru alloys for the anode of proton exchange membrane fuel cells (PEMFCs), hydrogen peroxide (HO) generation and the hydrogen oxidation reaction (HOR) properties of well-defined Ir-Ru bimetallic surfaces (Ru/Ir(111)) have been investigated using scanning electrochemical microscopy (SECM). Using thermal inter-diffusion of vacuum-deposited Ru and substrate Ir atoms, the topmost surface atomic ratios of Ru/Ir(111) were controlled changing the substrate temperature () during the deposition of 1 monolayer (ML)-thick Ru. Low-energy ion scattering spectroscopy (LE-ISS) estimated the Ru/Ir ratio to be 1 : 1 ( = 673 K), 1 : 2 ( = 773 K), and 1 : 4 ( = 873 K).