Looping metal-support interaction in heterogeneous catalysts during redox reactions

TL;DR

This study reveals a dynamic looping metal-support interaction in NiFe-Fe3O4 catalysts during hydrogen oxidation, showing how interfaces migrate and couple redox reactions at the atomic scale, using operando electron microscopy.

Contribution

It uncovers a novel type of dynamic metal-support interaction involving interface migration and coupling of redox reactions, advancing understanding of catalytic mechanisms.

Findings

Dynamic migrating interfaces observed during hydrogen oxidation.

Redox coupling between metal and support at the atomic scale.

Operando microscopy reveals previously unknown mechanistic insights.

Abstract

Metal-support interfaces fundamentally govern the catalytic performance of heterogeneous systems through complex interactions. Here, utilizing operando transmission electron microscopy, we uncovered a type of looping metal-support interaction in NiFe-Fe3O4 catalysts during hydrogen oxidation reaction. At the NiFe-Fe3O4 interfaces, lattice oxygens react with NiFe-activated H atoms, gradually sacrificing themselves and resulting in dynamically migrating interfaces. Meanwhile, reduced iron atoms migrate to the {111} surface of Fe3O4 support and react with oxygen molecules. Consequently, the hydrogen oxidation reaction separates spatially on a single nanoparticle and is intrinsically coupled with the redox reaction of the Fe3O4 support through the dynamic migration of metal-support interfaces. Our work provides previously unidentified mechanistic insight into metal-support interactions and underscores the transformative potential of operando methodologies for studying atomic-scale dynamics.