SHINERS for elucidating the relationship between size, shape and structure of oxide-supported Co nanoparticles and their performance in CO hydrogenation
Supervisor: Prof. dr. ir. Bert M. Weckhuysen
Heterogeneously catalyzed reactions typically take place at the solid/gas or solid/liquid interface. To characterize the binding and reaction of surface adsorbates, in situ techniques are needed that can identify surface species. Surface enhanced Raman spectroscopy (SERS) is a surface sensitive technique and is therefore a valuable method to study adsorbed species on a catalyst. For this technique, Au and Ag nanoparticles can be used to significantly enhance the electromagnetic field in the vicinity of the particle.
Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) is a relatively new SERS-based technique that makes use of gold or silver nanoparticles coated by a thin (<5 nm) oxide layer. This thin oxide layer prevents the sintering of the noble metal nanoparticle and blocks the direct chemical interaction of it with analytes. The electromagnetic enhancement is only slightly reduced by the coating.
Shell-isolated nanoparticles (SHINs) will be implemented to increase our understanding of the effect of size, shape and structure of cobalt nanoparticles on their performance in the Fischer-Tropsch reaction (FTR). Various sizes and shapes of gold nanoparticles with different oxide coatings will be synthesized and subsequently tested for their enhancing properties in SHINERS. Pre-synthesized cobalt nanoparticles will then be deposited onto these SHINs. These Co/oxide/Au systems will be investigated as a function of temperature, time and pressure to study the types of adsorbates and intermediates during the FTR.
Figure 1: (Top) Synthesis of SHINERS as a support material for catalysts, starting from bare gold nanoparticles, coated with an oxide layer and subsequently fixing catalyst particles on the surface. (Bottom) SHINERS used to study the Fischer-Tropsch process in realistic reaction conditions 
 Kim et al., Chem. Soc. Rev. 39, 4820-4844 (2010)
 Tian et al., Nature 464, 392-395 (2010)