XAFS, SAXS and HREM characterization of Pd nanoparticles capped with n-alkyl thiol molecules

We report a structural characterization of palladium nanoparticles, with an average diameter of 1.2 nm, capped with three different n-alkyl thiol molecules (n=12, 16 and 18). For this purpose several experimental techniques were used, namely X-ray absorption fine structure (XAFS), small angle X-ray scattering (SAXS) and high-resolution electron transmission microscopy (HRTEM). SAXS and HRTEM results yielded the sizes of the Pd nanoparticles in each sample. The effects of sulfur–palladium interaction on the structural and electronic properties of the studied material were derived from XAFS results. This study indicates the presence of sulfurized palladium in the bulk of the three studied capped Pd nanoparticles. Slight variations in the degree of sulfidation were detected for nanoclusters with different thiol chain lengths.