On the correlation between structure and catalytic activity of mesoporous ceria nanoparticles

Abstract

Mesoporous ceria nanoparticles (MCNs) have many superiorities such as higher surface area and more active reaction sites over their solid counterparts. However, the correlation between their structure and catalytic activity is poorly understood due to the lack of methods to synthesize MCNs with variable and well-defined structure parameters. In this study, a MCNs synthesis platform featured with strong structure parameter tuning capacity was established to synthesize plenty of MCNs for exploring their structure-catalytic activity relationship. The platform was composed of Ce(NO3)3·6H2O precursor, trioctylphosphine oxide (TOPO) ligand, and ethanol and octadecene (ODE) solvent. Through altering ligand/precursor ratio, ligand-precursor addition manner and reaction temperature, three groups of MCNs, totally twelve nanoparticles, were synthesized on the platform. The structure parameters of the synthesized MCNs were collected, and their catalytic activities including oxygen storage capacity (OSC), oxidase mimetic activity and photocatalytic activity were evaluated. The MCNs demonstrated wide range of nanoparticle diameter (40–115 nm), pore diameter (2.09–4.17 nm), pore volume (0.20–0.40 cm3 g−1), surface area (119.2–202.8 m2 g−1), and crystallite size (8.8–9.95 nm). These parameters played different roles in controlling different catalytic reactions, where pore size and crystallite size determined the oxygen storage capacity (OSC), pore size regulated the enzyme mimetic activity, and surface area dominated the photocatalytic activity. This study provided important insights into the correlation between structure and catalytic activity of MCNs, which was critical to the fabrication of MCNs based catalytic reactions.