Electrochemical sensing of hydrazine using hollow Pd/Ag dendrites prepared by galvanic replacement from choline Chloride-based deep eutectic solvents

The galvanic replacement reaction (GRR) is widely used for synthesizing hollow structures. This study proposes developing a Pd/Ag hollow structure modified electrode by GRR process in choline chloride-based deep eutec-tic solvents (DESs) to detect hydrazine in tap water and pond water. Irregular Ag dendrite was galvanically replaced in various deep eutectic solvents containing PdCl2. The characterization of Pd/Ag electrodes was eval-uated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results indicate that the viscosity of the DESs may influence the mass transport rate of the Pd (II) species and, thus, the displacement reaction rate. The Pd/Ag deposits obtained from choline chloride-ethylene glycol DES had hollow structures with good element distribution. The optimized Pd/Ag hollow structures required a lower overpotential for the electrochemical sensing hydrazine and possessed a detection limit of 1.68 mu M with a dynamic range of 4.98-559.68 mu M. The results of hydrazine recovery on samples were between 96.08 % and 97.29 %. These findings are valuable for future efforts to use the GRR approach to fabricate hollow materials in DESs.