Electrocatalytic performance of Ni@Pt core–shell nanoparticles supported on carbon nanotubes for methanol oxidation reaction

Ni@Pt (Ni-core, Pt-shell) nanoparticles deposited on surface of functionalized multi-walled carbon nanotubes (MWCNTs) have been prepared by a modified chemical co-reduction protocol and tested as promising electrocatalyst for methanol oxidation reaction (MOR). To delve comparison, Pt–Ni/MWCNTs (mixed structure) and Pt/MWCNTs have also been synthesized via conventional co-reduction method. Scanning electron microscopy (SEM) image demonstrates the open-ends of functionalized MWCNTs. Transmission electron microscopy (TEM) image indicates the presence of 5.7 ± 0.9 nm sized well-dispersed Ni@Pt core–shell particles on MWCNTs surface. Z-contrast images have been recorded via scanning transmission electron microscopy (STEM) using high-angle annular dark-field (HAADF) and annular bright-field (ABF) mode, which confirms the formation of core–shell nanostructures. Cyclic voltammetry results show that mass activities (MA) exhibited by Ni@Pt/MWCNTs (216.7 mA·mg^{− 1}Pt) for MOR in acidic medium are 2.25 and 1.47 times greater than those of Pt/MWCNTs (96.3 mA·mg^{− 1}Pt) and Pt–Ni/MWCNTs (147.9 mA·mg^{− 1}Pt) catalysts respectively. A pretty much similar comparison has been observed for MOR in basic medium. Moreover, chronoamperometric curves shows that Ni@Pt/MWCNTs has substantially better performance as compared to the other electrocatalysts in both acidic and alkaline media.