Structural effect of gold single crystal orientation on the spontaneous deposition of Rh nanoislands: Hydrogen evolution in acid solution

Abstract

Rh/Au(100) and Rh/Au(111) electrodes with Rh coverage below a monolayer are prepared by a spontaneous deposition method. Electrodes are characterized by AFM and XPS. Hydrogen evolution reaction (HER) is studied by linear sweep voltammetry in 0.1 M HClO4 solution. Results for gold single crystals with 50% Rh coverage, which have shown the best catalytic activity for HER are presented in this work. Enhanced catalytic activity of such bimetallic electrodes compared to the ones with higher Rh coverage is ascribed to the presence of smaller Rh islands, which provide suitable active surface sites. Rather strong electronic interaction between Rh deposit and gold substrates, which is manifested by the upshift of Rh3d5/2 photoelectron line, also contributes to their activity. Structural effect is manifested through a higher activity of 50% Rh/Au(111) than 50% Rh/Au(100), which is consistent with the difference in activity of respective bare gold single crystals.