Novel hydrazine sensors based on Pd electrodeposited on highly dispersed lanthanide-doped TiO2 nanotubes

Abstract

Electrodes made by electrodepositing Pd on lanthanide (Nd, Gd, Nd/Gd)-doped titania nanotubes (TNTs; prepared using a hydrothermal method) on Au substrates were applied to the detection of hydrazine in alkaline media. The performance of these devices was assessed using cyclic voltammetry and electrochemical impedance spectroscopy. The combination of conductive TNTs and lanthanides produced materials exhibiting remarkable electrocatalytic activity during the oxidation of hydrazine in a phosphate buffer solution at a pH of 10. Kinetic data acquired by voltammetry showed that the electro-oxidation of hydrazine is a purely diffusion-controlled process and that the reaction mechanism involves four electrons. A Nd-Gd-TNTs/Pd-modified Au electrode demonstrated highly reproducible behavior, a linear response from 10−5 to 10−2 mol L−1 hydrazine, a good sensitivity value of 288.3 μA mmol−1 L and a high level of stability during electrochemical experiments, with a limit of detection of 0.15 μmol L−1. The proposed voltammetry method was also used to analyze hydrazine in irrigation water samples from Al-Medina Al-Monawara City in conjunction with the standard addition technique. The results of this work demonstrate that lanthanide-doped TNTs could play an important role in environmental analysis.