Surface distortion as a unifying concept and descriptor in oxygen reduction reaction electrocatalysis

Les électrocatalyseurs à base de Pt contenant des défauts structuraux sont plus actifs et durables pour la réduction de l’oxygène à la cathode des PEMFC. L’utilisation de ces surfaces a permis de proposer un nouveau descripteur des propriétés catalytiques des électrocatalyseurs à base platine. Par R. Chattot, O. Le Bacq, V. Beermann, S. Kühl, J. Herranz, S. Henning, L. Kühn, T. Asset, L. Guétaz, G. Renou, J. Drnec, P. Bordet, A. Pasturel, A. Eychmüller, T. Schmidt, P. Strasser, L. Dubau, F. Maillard.
Tuning the surface structure at the atomic level is of primary importance to simultaneously meet the electrocatalytic performance and stability criteria required for the development of low-temperature proton-exchange membrane fuel cells (PEMFCs). However, transposing the knowledge acquired on extended, model surfaces to practical nanomaterials remains highly challenging. Here, we propose ‘surface distortion’ as a novel structural descriptor, which is able to reconciliate and unify seemingly opposing notions and contradictory experimental observations in regards to the electrocatalytic oxygen reduction reaction (ORR) reactivity. Beyond its unifying character, we show that surface distortion is pivotal to rationalize the electrocatalytic properties of state-of-the-art of PtNi/C nanocatalysts with distinct atomic composition, size, shape and degree of surface defectiveness under a simulated PEMFC cathode environment. Our study brings fundamental and practical insights into the role of surface defects in electrocatalysis and highlights strategies to design more durable ORR nanocatalysts.

Full paper. DOI: 10.1002/anie.201711068