Towards a Piezoelectric Electroanalytical Platform for Modulating Oxygen Reduction Reactivity on Platinum

Abstract

The oxygen reduction reaction (ORR) is key to a variety of renewable energy technologies. However, to date there is no experimental nor predicted material that achieves this reaction at the standard potential of 1.23 V vs. NHE. Here, we describe the first iteration of an electroanalytical platform for elucidating fundamental links between surface dynamics and ORR reactivity using chemomechanical perturbation. In our approach, a thin layer of Pt was deposited on a single crystal piezoelectric LiNbO3 substrate, which was micropatterned with contacts for effecting in situ electronically-controlled actuation. Our hypothesis is that actuation causes strain on the Pt catalyst, with concurrent changes in the reactivity toward the ORR. Actuation caused up to a ∼10 mV positive shift for the ORR reduction wave, and few mV displacements on a wave ascribed to surface oxide, when compared to curves in the absence of actuation. While mechanical deformation was below the limit of detection for XRD studies, a distinct effect was confirmed on the ORR when compared to control experiments including Ru(NH3)3+/2+ as surface-insensitive redox mediator. This work represents a first step toward a versatile platform for modulating the reactivity of electrocatalysts in situ to study structure-function relationships and discover optimal performance conditions.