Ultrasmall PdmMn1−mOx binary alloyed nanoparticles on graphene catalysts for ethanol oxidation in alkaline media

•The G/PdmMn1−mOx BACs are containing ultrafine and better dispersed nanoparticles.•BACs are employed as anode catalyst for ethanol oxidation in alkaline fuel cells.•Both Pd and Mn have alloyed in G/PdmMn1−mOx, & Mn presents in mixed-oxidized form.•The G/Pd0.5Mn0.5Ox catalyst has shown much superior mass activity and stability.•Ultrafine, well dispersed NPs and superior alloying are key factor for enhanced EOR.

A rare combination of graphene (G)-supported palladium and manganese in mixed-oxides binary alloyed catalysts (BACs) have been synthesized with the addition of Pd and Mn metals in various ratios (G/PdmMn1−mOx) through a facile wet-chemical method and employed as an efficient anode catalyst for ethanol oxidation reaction (EOR) in alkaline fuel cells. The as prepared G/PdmMn1−mOx BACs have been characterized by several instrumental techniques; the transmission electron microscopy images show that the ultrafine alloyed nanoparticles (NPs) are excellently monodispersed onto the G. The Pd and Mn in G/PdmMn1−mOx BACs have been alloyed homogeneously, and Mn presents in mixed-oxidized form that resulted by X-ray diffraction. The electrochemical performances, kinetics and stability of these catalysts toward EOR have been evaluated using cyclic voltammetry in 1 M KOH electrolyte. Among all G/PdmMn1−mOx BACs, the G/Pd0.5Mn0.5Ox catalyst has shown much superior mass activity and incredible stability than that of pure Pd catalysts (G/Pd1Mn0Ox, Pd/C and Pt/C). The well dispersion, ultrafine size of NPs and higher degree of alloying are the key factor for enhanced and stable EOR electrocatalysis on G/Pd0.5Mn0.5Ox.