Climbing with support: scaling the volcano relationship through support–electrocatalyst interactions in electrodeposited RuO2 for the oxygen evolution reaction

Abstract

We demonstrate an approach towards modulating electrocatalysis in an ultrathin RuO₂ oxygen electrocatalytic overlayer via optimal charge transfer between the support and the electrocatalyst. The governing heuristics for the choice of support that would result in ‘climbing up’ the volcano curve for oxygen evolution reaction (OER) electrocatalysts are delineated. Ultrathin Ru is deposited on metal coated over porous carbon supports, denoted by M/C, where M = Au, Cu, Pt, Ti and Ru, followed by the electrochemical oxidation of the Ru overlayer, which makes it possible for the support to retain its metallic character without getting oxidized to the less conductive metal oxide. An increase in the specific activity of thin RuO₂ is achieved with Au/C and Pt/C-supports against the Ru/C-support. The consolidated experimental and computational results suggest that the increase of the specific activity and subsequent ‘climbing up’ the volcano map for OER electrocatalysts is due to the interfacial charge transfer and support-induced electrocatalyst faceting. With the increase of the thickness, the support effect on the electrocatalyst activity gets reduced and only the conductivity of the support plays a dominant role in determining the OER activity.