Formic acid oxidation reaction on a PdxNiy bimetallic nanoparticle catalyst prepared by a thermal decomposition process using ionic liquids as the solvent

The nano-catalysts of Pd_xNi_y bimetallic nanoparticles (NPs, the nominal atomic ratios of Pd to Ni are 2:1, 3:2 and 1:1) supported on multi-walled carbon nanotubes (MWCNTs) (denoted as Pd_xNi_y/MWCNTs) have been synthesized by a thermal decomposition process using room temperature ionic liquids (RTILs) of N-butylpyridinium tetrafluoroborate (BPyBF₄) as the solvent. X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) were employed to characterize the morphology of the samples, revealing that the prepared Pd_xNi_y NPs were quite uniformly dispersed on the surface of MWCNTs with an average particle size of ∼8.0 nm. Formic acid oxidation reaction (FAOR) was investigated on the as-prepared catalysts by using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), demonstrating that the peak current on the Pd₃Ni₂/MWCNTs catalyst was about three times higher than that on the Pd/MWCNTs. The lower electrode potential and easier hydrogen evolution, based on the results obtained from chronopotentiometry and CV, respectively, were thought as the main reasons for the excellent electrocatalysis of the Pd₃Ni₂/MWCNTs toward formic acid oxidation reaction (FAOR) when compared to other samples.