In this study, diferent ionic liquids including 1-aminoethyl-3-methyl-imidazolium bromide [C2NH2mim][Br] (1), 1-methyl3-octylimidazolium chloride [C8mim][Cl] (2) and 1-methyl-3-octylimidazolium tetrafuoroborate [C8mim][BF4] (3) were applied to stabilize Pd nanoparticles (NPs) at toluene/water interface as thin flms. Field emission-scanning electron microscopy (FE-SEM) images showed puckered chains of ionic liquid (1) around the Pd NPs as fower nanostructures. Transmission electron microscopy (TEM) image of Pd/1 showed clearly core–shell nanostructures. Furthermore, applications of Pd/1, Pd/2 and Pd/3 were investigated in the Suzuki–Miyaura C–C coupling reaction in the presence and absence of ultrasonic waves, hydrogenation catalysis of p-nitrophenol reduction and methanol oxidation reaction. Interestingly, Jf (forwarding current density due to methanol oxidation) was observed only for Pd/1. We believe that interactions of –NH2 and imidazolium groups of ionic liquid 1 with Pd particles are very important in producing of puckered shells around the Pd NPs. Injection of electron density from –NH2 group and Br− of ionic liquid 1 to Pd content tends to Pd be softer than other ionic liquids (2 or 3). This efect weakens the strength of Pd–O and facilitates the intermolecular reductive elimination between Pd–O and Pd–C≡O in rate-determining step of methanol oxidation to produce CO2 product. However, electron releasing group accelerates the increasement in negative charge density of metal accelerates intramolecular or intermolecular reduction elimination.
