Thermally activated nucleation and growth of cobalt and nickel oxide nanoparticles on porous silica

Integrating mesoscale to the molecular level understanding of nanoparticle nucleation phenomena can drive the bottom-up synthesis approach for target applications. The authors studied the thermal evolution of binary metal oxide (cobalt and nickel oxides) nanoparticle structural phases on porous silica host from over wide spatial scale using multimodal analysis involving scanning transmission electron microscopy, x-ray absorption near-edge spectroscopy (XANES), and nuclear magnetic resonance (NMR) spectroscopy 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 calcination temperature. ²⁹Si NMR analysis revealed the role of surface functional groups of silica host for silicate composite formation, which is corroborated by DFT studies.