Lanthanum modulated reaction pacemakers on a single catalytic nanoparticle

Promoters are important in catalysis, but the atomistic details of their function and particularly their role in reaction instabilities such as kinetic phase transitions and oscillations are often unknown. Employing hydrogen oxidation as probe reaction, a Rh nanotip for mimicking a single Rh nanoparticle and field electron microscopy for in situ monitoring, we demonstrate a La-mediated local catalytic effect. The oscillatory mode of the reaction provides a tool for studying the interplay between different types of reaction pacemakers, i.e., specific local surface atomic configurations that initiate kinetic transitions. The presence of La shifts the bistable reaction states, changes the oscillation pattern and deactivates one of two pacemaker types for the La-free surface. The observed effects originate from the La-enhanced oxygen activation on the catalyst. The experimental observations are corroborated by micro-kinetic model simulations comprising a system of 25 coupled oscillators. Promoters are important in catalysis, but their exact role requires further investigation. Here, by imaging complex spatio-temporal pattern formation during the oscillatory reaction, the authors reveal the effect of La-modulation to be related with higher oxygen binding energy at nanostructured pacemaker regions.

Automated summary

Promoters play an important role in catalysis, but their function and role in reaction instabilities are often unknown. This study demonstrates the local catalytic effect of La in hydrogen oxidation reaction using Rh nanotip as a mimic of single Rh nanoparticle. The presence of La shifts the reaction states, changes the oscillation pattern, and deactivates one of the pacemaker types. The effect originates from the enhanced oxygen activation on the catalyst.