An attempt to correlate surface physics with chemical properties: molecular beam and Kelvin probe investigations of Ce 1-x Zr x O 2 thin films

• Published in: Physical chemistry chemical physics : PCCP 2016-10, Vol.18 (39), p.27594-27602
• Main Authors: Kolekar, Sadhu K, Dubey, Anjani, Date, Kalyani S, Datar, Suwarna, Gopinath, Chinnakonda S
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/C6CP04700A

What is the correlation between physical properties of the surfaces (such as surface potential, electronic nature of the surface), and chemical and catalysis properties (such as chemisorption, sticking probability of surface)? An attempt has been made to explore any correlation that might exist between the physical and chemical properties of thin film surfaces. Kelvin probe microscopy (KPM) and the molecular beam (MB) methods were employed to carry out the surface potential, and oxygen adsorption and oxygen storage capacity (OSC) measurements on Ce Zr O thin films. A sol-gel synthesis procedure and spin-coating deposition method have been applied to make continuous nanocrystalline Ce Zr O (x = 0-1) (CZ) thin films with uniform thickness (35-50 nm); however, surface roughness and porosity inherently changes with CZ composition. MB studies of O adsorption on CZ reveal high OSC for Ce Zr O , which also exhibits highly porous and significantly rough surface characteristics. The surface potential observed from KPM studies varied between 30 and 80 mV, with Ce-rich compositions exhibiting the highest surface potential. Surface potential shows large changes after reduction or oxidation of the CZ film demonstrating the influence of Ce /Ce on surface potential, which is also a key to catalytic activity for ceria-based catalysts. The surface potential measured from KPM and the OSC measured from MB vary linearly and they depend on the Ce /Ce ratio. More and detailed studies are suggested to arrive at a correlation between the physical and chemical properties of the surfaces.