Pt–Ni bimetallic composite nanocatalysts prepared by using multi-walled carbon nanotubes as reductants for ethanol oxidation reaction

•PtNix are prepared by a hydrothermal reaction in the presence of carbon nanotubes.•Two parameters describing the electrocatalytic ability of a catalyst are proposed.•The PtNi3 shows the best activity towards EOR among all the as-prepared catalysts.

The multi-walled carbon nanotubes (MWNTs) are introduced as reductants to prepare bimetallic PtNix composite nanocatalysts via a hydrothermal reaction for the investigation of ethanol oxidation reaction (EOR). The crystal structure and elemental analysis of PtNix/MWNTs nanocatalysts are characterized by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS), respectively. The morphologies of these nanocatalysts are observed by transmission electron microscopy (TEM) and scanning electron microscope (SEM). The results reveal that the PtNix nanocatalysts with a nanoparticle size ranging from 6 to 13 nm are immobilized on the surface of MWNTs. The electrocatalytic activities of the PtNix/MWNTs nanocatalysts for EOR in alkaline media are examined using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA). The onset potential of EOR in the nanocatalyst of PtNi3/MWNTs is negatively shifted for about 190 mV as compared to that in the nanocatalyst of Pt/MWNTs. The current for the forward anodic peak of EOR in the PtNi3/MWNTs nanocatalyst is about 2.5 times higher than that of pure Pt/MWNTs.