Migration and aggregation of Pt atoms on metal oxide-supported ceria nanodomes control reverse water gas shift reaction activity

Single-atom catalysts (SACs) are particularly sensitive to external conditions, complicating the identification of catalytically active species and active sites under in situ or operando conditions. We developed a methodology for tracing the structural evolution of SACs to nanoparticles, identifying the active species and their link to the catalytic activity for the reverse water gas shift (RWGS) reaction. The new method is illustrated by studying structure-activity relationships in two materials containing Pt SACs on ceria nanodomes, supported on either ceria or titania. These materials exhibited distinctly different activities for CO production. Multimodal operando characterization attributed the enhanced activity of the titania-supported catalysts at temperatures below 320 C to the formation of unique Pt sites at the ceria-titania interface capable of forming Pt nanoparticles, the active species for the RWGS reaction. Migration of Pt nanoparticles to titania support was found to be responsible for the deactivation of titania-supported catalysts at elevated temperatures. Tracking the migration of Pt atoms provides a new opportunity to investigate the activation and deactivation of Pt SACs for the RWGS reaction. Platinum dispersed on metal oxide supports is widely used for industrially important catalysis such as the reverse water gas shift reaction, but active site migration and subsequent alterations in catalytic performance are still not fully understood. Here, the use of platinum on ceria nanodomes shows the detrimental effect of migration of platinum nanoparticles to titania supports at elevated temperatures.

Automated summary

Single-atom catalysts are sensitive to external conditions, and tracking their structural evolution can identify active species and active sites. The migration of platinum nanoparticles affects catalytic activity.