Reaction-induced changes in structure and activity of supported platinum catalysts investigated in situ: from single atoms to clusters
Résumé
Stimulated by recent advances in scanning transmission electron microscopy (STEM), single-atom catalysts (SACs) have become prominent materials in heterogeneous catalysis.[1] In spite of the numerous reports on promising catalytic performance and noble-metal saving, single-atom stabilization remains a challenge – in particular for noble metals on oxides.[2] In addition, single atoms are not necessarily more efficient than their cluster or nanoparticle counterparts.[3] In this presentation, the previous issues will be illustrated for two prototypical catalytic systems: CO oxidation on Pt/Al2O3 and photocatalytic hydrogen evolution reaction over Pt/TiO2. The combined use of catalytic testing, STEM, operando X-ray and infrared absorption spectroscopies, and DFT calculations, reveal the influence of the reactive environment on Pt nuclearity and oxidation state (generally consisting in clustering and reduction, which in turn correlate to changes in catalytic activity.[4–7] From this knowledge, strategies can be suggested to stabilize the metals in an ultradispersed state.
References:
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6. Dessal, C.; Martínez, L.; Maheu, C.; Len, T.; Morfin, F.; Rousset, J.-L.; Puzenat, E.; Afanasiev, P.; Aouine, M.; Soler, L.; Llorca, J.; Piccolo, L. J. Catal. 2019, 375, 155–163.
7. Piccolo, L.; Afanasiev, P.; Morfin, F.; Len, T.; Dessal, C.; Rousset, J. L.; Aouine, M.; Bourgain, F.; Aguilar-Tapia, A.; Proux, O.; Chen, Y.; Soler, L.; Llorca, J. ACS Catal. 2020, 10 (21), 12696–12705.