Ni@Pt nanodisks with low Pt content supported on reduced graphene oxide for methanol electrooxidation in alkaline media

Ni@Pt/RGO nanodisks were synthesized and the electrooxidation of CO and methanol studied. The morphology, structure and composition of the Ni nanodisks were characterized by atomic force microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Electrochemical characterization was performed by cyclic voltammetry and chronoamperometry. Results showed that Pt galvanostatically replaced Ni atoms maintaining the original (111) and (200) crystalline domains. XPS analysis indicates that negative charge transfer from Ni to Pt in the nanodisks and the presence of Ni-oxides/hydroxides species on the surface are key factors for the high electrochemical activity. The catalysts with low Pt content displayed higher CO tolerance and activity towards methanol electrooxidation. The synergy of the bifunctional effect and the NiPt electronic interaction makes Ni@Pt/RGO nanodisks good candidates for the methanol oxidation reaction in alkaline media, and consequently, in direct methanol alkaline membrane fuel cells.