Using ionic liquid as the solvent to prepare Pd–Ni bimetallic nanoparticles by a pyrolysis method for ethanol oxidation reaction

Room temperature ionic liquids (RTILs) of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) is used as the solvent for the first time to prepare multi-walled carbon nanotubes (MWCNTs) supported nanocomposite catalysts of Pd_xNi_y (atomic ratios of Pd to Ni are 1:1, 1:1.5, 1:2, and 1:2.5) nanoparticles (denoted as Pd_xNi_y/MWCNTs) by using a simple pyrolysis process. The Pd_xNi_y/MWCNTs catalysts are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results show that the Pd_xNi_y nanoparticles (NPs) are quite uniformly dispersed on the surface of MWCNTs with an average crystallite size of ∼7.0 nm. The electro-catalytic activity of the Pd_xNi_y/MWCNTs catalysts for ethanol oxidation reaction (EOR) is examined by cyclic voltammetry (CV). It is revealed that the onset potential is ∼80 mV lower and the peak current is about three times higher for ethanol oxidation for MWCNT catalysts with Pd₁Ni_1.5 compared to those of Pd/MWCNTs. The catalytic mechanisms of the Pd₁Ni_1.5/MWCNTs towards EOR are also proposed and discussed. - Highlights: • Introducing ionic liquids to the pyrolysis process for the preparation of Pd_xNi_y nanoparticles. • Pd_xNi_y nanoparticles with an average particle size of ∼7.0 nm were fabricated. • The peak current of EOR was about three times higher at Pd₁Ni_1.5 compared to those of Pd