Cation Effects on the Acidic Oxygen Reduction Reaction at Carbon Surfaces
Jessica Hübner, Lanna E.B. Lucchetti, Hong Nhan Nong, Dmitry Sharapa, Benjamin Paul, Matthias Kroschel, Jiaqi Kang, Detre Teschner, Silke Behrens, Felix Studt, Axel Knop‐Gericke, Samira Siahrostami, Peter Strasser
Abstract
High Resolution Image Download MS PowerPoint Slide Hydrogen peroxide (H 2 O 2 ) is a widely used green oxidant. Until now, research has focused on the development of efficient catalysts for the two-electron oxygen reduction reaction (2e – ORR). However, electrolyte effects on the 2e – ORR have remained little understood. We report a significant effect of alkali metal cations (AMCs) on carbons in acidic environments. The presence of AMCs at a glassy carbon electrode shifts the half wave potential from −0.48 to −0.22 V RHE . This cation-induced enhancement effect exhibits a uniquely sensitive on/off switching behavior depending on the voltammetric protocol. Voltammetric and in situ X-ray photoemission spectroscopic evidence is presented, supporting a controlling role of the potential of zero charge of the catalytic enhancement. Density functional theory calculations associate the enhancement with stabilization of the *OOH key intermediate as a result of locally induced field effects from the AMCs. Finally, we developed a refined reaction mechanism for the H 2 O 2 production in the presence of AMCs.