Methanol dehydrogenation and oxidation on Pt1–XNiX/CNTs at low temperature: Effect of Ni addition

Abstract

This study reports the effect on catalytic activity resulting from Ni incorporation in Pt nanoparticles supported on carbon nanotubes (CNTs) for electrochemical methanol oxidation at low temperature in acidic conditions. Chemical composition, morphology and structure of the Pt1–XNiX/CNTs (X = 0, 0.1, 0.2, 0.3, 0.4, 0.5) catalysts were studied by EDS, SEM, XRD, TEM and TGA. The catalytic activity of the prepared materials in methanol electro-oxidation reaction was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). The results of catalytic activity of the nanostructured materials showed a volcano-type relationship between the Ni relative concentration current density. The enhancement of catalytic activity was attributed to changes in surface electronic structure of Pt nanoparticles that impacted in an increment of active sites for methanol dehydrogenation and oxidation processes. On the other hand, high concentration of Ni (concentration ≥ 30 at.%) in Pt nanoparticles caused a substantial decrease of the catalytic activity due to a depletion of active sites for the methanol dehydrogenation process. The highest catalytic activity was observed when the Ni relative concentration reaches 30 at.%.