Grain boundary boosting the thermal stability of Pt/CeO2 thin films

Understanding how defect chemistry of oxide material influences the thermal stability of noble metal dopant ions plays an important role in designing high-performance heterogeneous catalytic systems. Here we use in-situ ambient-pressure X-ray photoemission spectroscopy (APXPS) to experimentally determine the role of grain boundary in the thermal stability of platinum doped cerium oxide (Pt/CeO2). The grain boundaries were introduced in Pt/CeO2 thin films by pulsed laser deposition without significantly change of the surface microstructure. The defect level was tuned by the strain field obtained using a highly/low mismatched substrate. The Pt/CeO2 thin film models having well defined crystallographic properties but different grain boundary structural defect levels provide an ideal platform for exploring the evolution of Pt-O-Ce bond with changing the temperature in reducing conditions. We have direct demonstration and explanation of the role of Ce3+ induced by grain boundaries in enhancing Pt2+ stability. We observe that the Pt2+-O-Ce3+ bond provides an ideal coordinated site for anchoring of Pt2+ ions and limits the further formation of oxygen vacancies during the reduction with H-2. Our findings demonstrate the importance of grain boundary in the atomic-scale design of thermally stable catalytic active sites.

Automated summary

Understanding the role of grain boundaries in the thermal stability of platinum doped cerium oxide (Pt/CeO2) is crucial for designing high-performance catalytic systems. In this study, in-situ ambient-pressure X-ray photoemission spectroscopy (APXPS) was used to investigate the effect of grain boundaries on the stability of Pt/CeO2. The results demonstrate that grain boundaries enhance the stability of Pt2+ ions by providing an ideal coordinated site for anchoring and limiting the formation of oxygen vacancies during the reduction process.