Preperation and characterization of metal nanoparticles modified ruthenium-vanadium oxide composite electrodes and application to hydrazine determination

Nanocomposite based metal nanoparticles and metal oxides have been extensively researched in the recent years for their use in sensors and fuel cell technology due to their superior electrocatalytic properties. Hydrazine is an ideal fuel for direct hydrazine fuel cell systems. Hydrazine is also a toxic material. Therefore, it is important to develop sensitive detection methods for environmental samples. In this study, nano-size vanadium and ruthenium oxide mixtures (VOx-RuOx) films were synthesized pulsed deposition (PD) on carbon nanotubes (CNT), and then decorated with metal nanoparticles to fabricate the VOx-RuOx film for hydrazine oxidation. Metal nanoparticles such as Au or Pt are coated on the metal oxides surfaces with cyclic voltammetry. Modified surfaces are characterized by Scanning Electron Microscope (SEM), X-ray diffraction spectroscopy (XRD) and cyclic voltammetry (CV). The electrochemical behavior of hydrazine was investigated with voltammetry at the bare and modified electrodes. A new electrochemical hydrazine sensor platform was fabricated. In experimental studies, the effect of phosphate buffer pH (2-12), metal oxide concentration, metal oxide mixture (VOx-RuOx) molar ratio, the effect of pulsed deposition (PD) potential, metal concentration (Au3+ and Pt4+) and cycle number, etc. were optimized. The pH of the buffer solution was chosen as 10.0. In addition, linear sweep voltammetry and amperometric technique were used for sensitive determinations of hydrazine. The working range of the calibration graphs for AuNP/VOx-RuOx/CNT/GCE was founded in the range of 1-1000 µM. The limit of dedection (LOD) was calculated to be 0.4 µM. Interference studies for hydrazine (metal ions and organic compound) were examined. Also, the prepared new sensor platforms were studied for repeatability between inter-day and intra-day. As a real example analysis, the hydrazine determination in the Gediz River sample was tested on the AuNP/VOx-RuOx/CNT/GC electrode. The recovery range of hydrazine was 97.1% and 108%.