Thermally stable surfactant-free ceria nanocubes in silica aerogel

DOI: 10.1016/j.jcis.2020.09.044

Authors: Francesco Caddeo (University of Kent) , Alberto Casu (King Abdullah University of Science and Technology (KAUST)) , Danilo Loche (University of Kent) , Lucy M. Morgan (University of Kent) , Gavin Mountjoy (University of Kent) , Colm O'regan (King Abdullah University of Science and Technology (KAUST)) , Maria F. Casula (University of Cagliari) , Shusaku Hayama (Diamond Light Source) , Anna Corrias (University of Kent) , Andrea Falqui (King Abdullah University of Science and Technology (KAUST))
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Colloid And Interface Science

State: Published (Approved)
Published: September 2020
Diamond Proposal Number(s): 19013

Abstract: Surfactant-mediated chemical routes allow one to synthesize highly engineered shape- and size-controlled nanocrystals. However, the occurrence of capping agents on the surface of the nanocrystals is undesirable for selected applications. Here, a novel approach to the production of shape-controlled nanocrystals which exhibit high thermal stability is demonstrated. Ceria nanocubes obtained by surfactant-mediated synthesis are embedded inside a highly porous silica aerogel and thermally treated to remove the capping agent. Powder X-ray Diffraction and Scanning Transmission Electron Microscopy show the homogeneous dispersion of the nanocubes within the aerogel matrix. Remarkably, both the size and the shape of the ceria nanocubes are retained not only throughout the aerogel syntheses but also upon thermal treatments up to 900 °C, while avoiding their agglomeration. The reactivity of ceria is measured by in situ High-Energy Resolution Fluorescence Detected - X-ray Absorption Near Edge Spectroscopy at the Ce L3 edge, and shows the reversibility of redox cycles of ceria nanocubes when they are embedded in the aerogel. This demonstrates that the enhanced reactivity due to their prominent {100} crystal facets is preserved. In contrast, unsupported ceria nanocubes begin to agglomerate as soon as the capping agent decomposes, leading to a degradation of their reactivity already at 275 °C.

Journal Keywords: Ceria; Nanocubes; Capping agents; SiO2; Aerogel

Subject Areas: Materials, Chemistry, Physics


Instruments: I20-Scanning-X-ray spectroscopy (XAS/XES)

Documents:
1-s2.0-S0021979720312236-main.pdf