Gold–nickel/titania nanotubes as electrocatalysts for hydrazine oxidation

• Self-ordered titania nanotubes as a support for catalysts.
• Electrocatalysts for the oxidation of hydrazine.
• Fabrication of catalysts by galvanic displacement of Ni layer by Au enables growth of nano-sized metal particles.
• Au(Ni)/TiO2-NTs are efficient electrocatalysts for hydrazine oxidation.

This work is focused on the study of self-ordered titania nanotube arrayed electrodes for preparation of efficient gold–nickel/titania nanotubes electrocatalysts (denoted as Au(Ni)/TiO2-NTs) for the oxidation of hydrazine in an alkaline medium. The Au(Ni)/TiO2-NTs catalysts were prepared by partial galvanic displacement of an electroless Ni layer, deposited on the self-ordered titania, by Au nanoparticles from the gold-containing solution. The morphology, structure and composition of the prepared nanostructured catalysts were examined by Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Analysis (EDAX), X-ray diffraction (XRD) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The electrocatalytic activity of the prepared catalysts was investigated towards the oxidation of hydrazine in an alkaline medium by means of cyclic voltammetry and chronoamperometry. It was found that the prepared Au(Ni)/TiO2-NTs catalysts with low Au loadings possess more than ten-twenty times higher electrocatalytic activity towards the oxidation of hydrazine in an alkaline medium as compared to that of Au electrodeposited on TiO2-NTs and Ni/TiO2-NTs, presumably due to formation of Au nanoparticles of high dispersivity as well as formation of Ni solid solution in gold.