The thermal sintering under oxidative conditions of Rh nanoparticles supported on oxides characterized by very different oxygen storage capacities (OSC) and labilities was studied at 750 and 850 °C. Under sintering conditions, significant particle growth occurred for Rh/γ-Al2O3 (up to 120% at 850 °C). In striking contrast, Rh/ACZ (alumina–ceria–zirconia) and Rh/CZ (ceria–zirconia) exhibited marked resistance to sintering, and even moderate (ca. −10% at 850 °C) to pronounced (ca. −60% at 850 °C) redispersion of the Rh. A model is proposed based on a double-layer description of metal–support interactions assigned to back-spillover of labile oxygen ions onto the Rh particles, accompanied by trapping of atomic Rh by the resulting surface oxygen vacancies. This model accounts for the observed resistance to sintering and actual redispersion of Rh, consistent with both alternative sintering mechanisms, namely Ostwald ripening (OR) or particle migration and coalescence (PMC).
Bibliographical noteThis is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
Funding: This research was co-financed by the European Union and Greek national funds through the Operational
Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH–CREATE–INNOVATE
(project code: T1E∆K-00782).
- Alumina ceria zirconia
- Atom trapping
- Metal-support interactions
- Nanoparticles sintering
- Ostwald ripening
- Oxygen storage capacity
- Particle migration and coalescence