Transmitting metal–oxide interaction by solitary chemical waves: H2 oxidation on ZrO2 supported Rh

Abstract

The interaction of catalytically active metal particles with supporting oxide surfaces is still an actual topic in catalysis. Particularly, the exact role of metal-support boundary effects, caused by the active sites along the metal–oxide interface, is not entirely clear. Here we demonstrate a long-range effect of metal–oxide boundaries in a Rh/ZrO2 model system on the reactivity of Rh in H2 oxidation. The atomically narrow (<1 nm) interface between a Rh particle and ZrO2 causes a remarkable shift in the kinetic behavior of the entire µm-sized particle, i.e. affecting metal sites thousands of nanometers away from the interface. The effect was directly observed by photoemission electron microscopy (PEEM) using the kinetics by imaging approach which allows the evaluation of reaction kinetics for individual supported particles within the resolution limit of PEEM. The observed effect is attributed to the critical role of the perimeter sites for the initiation of activation and deactivation fronts (chemical waves) during H2 oxidation, which transmit the metal–oxide interface effect over the entire Rh particle.