Synthesis and characterization of palladium nanoparticles immobilized on ZrO2 nanotubes as a new highly active electrode for methanol electro-oxidation

Palladium nanoparticles/zirconium oxide nanotubes/zirconium (Pd-NPs/ZrO2-NTs/Zr) electrodes were prepared by electroless plating method. ZrO2-NTs consisting of individual nanotubes of about 60–80 nm diameters were fabricated by anodizing Zr foil in electrolyte solution containing dimethylformamide, glycerol, water and ammonium fluoride. The morphology and surface characteristics of ZrO2-NTs and Pd-NPs/ZrO2-NTs/Zr electrodes studied using scanning electron microscopy as well as energy dispersive X-ray spectroscopy. The results revealed that Pd-NPs were homogeneously deposited on the surface of ZrO2-NTs. Moreover, electrocatalytic properties of Pd-NPs/ZrO2-NTs/Zr and flat Pd electrodes toward methanol oxidation were investigated using cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. The results indicated that Pd-NPs/ZrO2-NTs/Zr electrode represents an enhanced electrocatalytic activity and better stability for methanol oxidation compared to flat Pd. Thus, the Pd-NPs/ZrO2-NTs/Zr catalyst is expected to be a promising electrode material for direct methanol fuel cells. Additionally, the effects of scan rate, methanol concentration and temperature dependency of methanol oxidation on Pd-NPs/ZrO2-NTs/Zr electrode have been explored in this study.