PNNL

Abstract

Atomic level engineering of nanoparticles (NPs) with ability to precisely tune its functional properties can help us realize many promising applications in catalytic science. Such a bottom-up approach would require fundamental level understanding of nucleation and subsequent chemical evolution of nanoparticles during synthesis process. In particular, transition metal based nanoparticles such as Cobalt (Co), Nickel (Ni), Iron (Fe), Paladium (Pd), and Platinum (Pt) can serve as catalysts for many important reactions such as syngas conversion, hydrogenation-dehydrogenation reactions and hydro-deoxygenation reactions. The porous SiO2 is widely used as support medium due to their chemical inertness under reducible and reactive chemical environments often encountered during catalytic process. Nevertheless, even chemically benign SiO2 can have interaction with catalyst particles under high temperatures and adversely affect catalytic activity due to the presence of reactive surface functional groups. Although the influence of the support on catalyst activity and the selectivity is widely studied with respect to the strong metal-support interaction (SMSI) and more recently on the electronic effect of metal-support interaction (EMSI), the choice of support and the catalyst preparation method are still mostly determined by the empirical optimization. For this study, we focus on local structural evolution of cobalt and nickel oxide nanoparticles and its interaction with SiO2 support using multi-modal spectroscopic approach involving X-ray absorption spectroscopy (XAS), nuclear magnetic resonance (NMR) and density functional theory (DFT) based computational methods.