PNNL

Abstract

Integrating mesoscale to the molecular level understanding of nanoparticle nucleation phenomena can drive the bottom-up synthesis approach for target applications. We studied the thermal evolution of cobalt and nickel oxide nanoparticle structural phases on porous silica host from over wide spatial scale using multi-modal analysis involving scanning transmission electron microscope (STEM), X-ray absorption (XANES) and nuclear magnetic resonance (NMR) spectroscopies along with density functional theory (DFT) based calculations. The TEM analysis reveals thermally activated nanoparticle clustering and subsequent interaction with the porous host material. The Co and Ni K-edge XANES spectra revealed the evolution from metal hydroxide to metal oxide and subsequently metal silicate composites with calcinination temperature. 29Si NMR analysis revealed the role of surface functional groups of silica host for silicate composite formation which is corroborated by DFT studies.